JP4083287B2 - Fukuyama-type congenital muscular dystrophy-causing protein - Google Patents

Description

【図面の簡単な説明】
【図１】染色体９ｑ３１上のＦＣＭＤ候補領域の概略図である。
連鎖不平衡マッピング法及び創始者ハプロタイプマッピング法の為に用いられたＤＮＡマイクロサテライトの位置を示す。ＦＣＭＤ原因遺伝子は、Ｄ９Ｓ２１７０の動原体側ごく近くに位置していると推定された。
コスミドコンティグを構成する個々のコスミドは水平の線で、またＥｃｏＲＩ部位は短い垂直線で示した。図中、ＮはＮｏｔＩを意味し、また、共通の変異である〜３ｋｂ挿入の位置も同時に示した（3-kb insertion）。ＦＣＭＤ ｃＤＮＡのゲノム上での拡がりをマップの下に、転写の方向を示す矢印と共に示した。
【図２】〜【図３】はそれぞれＦＣＭＤ患者におけるサザン分析（電気泳動像）を示す図面に代わる写真である。
【図２】ＰｖｕII、ＰｓｔＩ又はＢｇｌIIで消化したゲノムＤＮＡにおける結果（電気泳動像）を示す図面に代わる写真である。レーン１〜３は、１３８−１９２−１４７−１８３創始者ハプロタイプのホモ接合体である患者；レーン４は、創始者ハプロタイプのヘテロ接合体である患者；レーン５は、正常者のコントロールである。プローブとして、コスミドクローンｃＥ６のインサート全体を使用した。
正常者コントロールで見られたバンドは、ＦＣＭＤ患者で消失しており（矢印）、〜８ｋｂにシフトしているのが観察された（ＰｖｕII）。同様に、ＰｓｔＩ又はＢｇｌIIで消化したＤＮＡについても、正常なバンドの一つが消失し、該消失バンドよりも大きい新規なバンドが出現した。
【図３】ｃＥ６のインサートの中の一部の断片プローブＥ６ｆ３を用いたＰｖｕII消化物のサザンハイブリダイゼーションの結果（電気泳動像）を示す図面に代わる写真である。Ｎは、正常者コントロールを、Ｆは、ＦＣＭＤ患者を示す。
【図４】〜【図５】は、ＦＣＭＤ cＤＮＡのヌクレオチド配列及びその配列から推定されるアミノ酸配列を示す図である。
【図４】ＦＣＭＤ cＤＮＡのヌクレオチド配列（１〜２１００位）及びその配列から推定されるアミノ酸配列を示す図である。推定される疎水性シグナル配列領域及びトランスメンブランドメイン領域は下線（実線）で、Ｎ−結合グリコシレーション部位は点線で、可能なＮ−ミリストリレーション部位は「＊」で、プロテインキナーゼＣ及びチロシンキナーゼで潜在的にリン酸化され得るセリン／スレオニン及びチロシン残基は、それぞれ「％」及び「＾」で示されている。また、本発明により明らかにされた突然変異にかかるヌクレオチド（２５０位、２９８−２９９位）を斜で囲んで示す。
【図５】図４に続く、ＦＣＭＤ cＤＮＡのヌクレオチド配列（２１０１〜７３８１位）を示す図である。利用されたポリ（Ａ）付加部位を「＄」で、及び創始者挿入変異部位を矢印で示す。
【図６】〜【図７】はそれぞれＦＣＭＤ原因遺伝子のノーザン分析（電気泳動像）を示す図面に代わる写真である。
【図６】ヒト組織中でのＦＣＭＤ ｍＲＮＡの組織特異的な発現を示す図面に代わる写真である。表示された８種のヒト組織に由来するポリ（Ａ）＋ＲＮＡ（２μｇ）を含むＲＮＡブロット（Clontech）を、ＦＣＭＤ ｃＤＮＡプローブ（クローンII−５、上段）及びβ−アクチンｃＤＮＡプローブ（下段）とハイブリダイズした結果を示す。
【図７】ＦＣＭＤ患者及び健常者コントロールのリンパ芽球に由来するポリ（Ａ）＋ＲＮＡ（２μｇ）を含むＲＮＡブロットを用いて、上記と同一プローブにてハイブリダイズした結果を示す図面に代わる写真である。
挿入配列をホモ接合的にまたはヘテロ接合的に有するＦＣＭＤ患者においては、シグナルは殆どゼロかまたは異常に低かった。
【図８】１３８−１９２−１４７−１８３創始者ハプロタイプを示す二世代ＦＣＭＤ家系における挿入アレルのメンデル遺伝を示す（電気泳動像）、写真に代わる図面である。
【図９】〜【図１１】はそれぞれＦＣＭＤ患者の点突然変異の家系内分離を示す図である。
【図９】ＦＣＭＤ患者（ＨＭ、ＴＩ）の点突然変異の家系内分離を示すサザン分析（電気泳動像）を示す図面に代わる写真である。サザン分析は、患者ＨＭ及びＴＩが、それぞれ父親及び母親から遺伝して有する創始者挿入アレルに対して、ヘテロ接合性であることを示した。患者ＴＩは、米国人の父親及び日本人の母親の娘である。
【図１０】ＦＣＭＤ患者の点突然変異の家系内分離に関し、蛍光配列分析の結果を示す図である。かかる分析により、患者の配列は、置換（Ｃ→Ｔ250）及び欠失（del:298-299）の突然変異を有していることが分かった。これらの変異はいずれも翻訳の不完全な停止を示す（Ｒ４７Ｘ及びフレームシフト）。
センス鎖の配列が示されている。
【図１１】ＡＧＣＴ配列部位でＤＮＡを切断するエンドヌクレアーゼＡｌｕＩを用いて、ＨＭ家系及び同じハプロタイプを有する他の５家系（ＹＳ、ＲＭ、ＡＧ、ＡＴ、及びＡＹ）について変異を確認した結果（電気泳動像）を示す図面に代わる写真である。Ｃ→Ｔ２５０変異対立遺伝子は、正常対立遺伝子がＡＧＣＣであるのに対して、ＡＧＣＴ配列を有しているので、ＡｌｕＩ消化によって区別することができる。この場合、正常ＰＣＲ生成物のサイズは１４２ｂｐとなり、変異対立遺伝子のＡｌｕＩ消化物は１１３ｂｐ、２５ｂｐ及び４ｂｐ断片に分かれる（小さい断片は過剰のプライマーが存在している為検出できなかった）。
ＨＭ家系では、（挿入変異を持たない）変異対立遺伝子は母親に由来し、この変異はマイクロサテライトによるハプロタイプと共に遺伝していた。一方、ＳＳＣＰ分析により、患者ＴＩにおける２ｂｐ欠失は西洋人の父親に由来することが示された（右側、矢印）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a Fukuyama type congenital muscular dystrophy-causing protein (hereinafter also referred to as FCMD-causing protein), and more particularly to a novel protein that causes the onset of Fukuyama-type congenital muscular dystrophy due to its dysfunction. The present invention also relates to a novel gene encoding such a protein (hereinafter also referred to as FCMD causative gene). Furthermore, the present invention relates to a mutant that causes the genetic abnormality of the gene causing FCMD, in particular, the onset of Fukuyama type congenital muscular dystrophy.
[0002]
[Prior art]
Muscular dystrophy is an inherited degenerative disease mainly occurring in skeletal muscle, and is classified into 10 or more types according to clinical features.
[0003]
For sexual dystrophy, Duchenne muscular dystrophy (DMD), the most common muscular dystrophy, dystrophin has been identified as a defective gene product causing its pathogenesis by the positional cloning method. As a result, intensive research has been conducted on the pathologic mechanism. In addition, since the discovery of dystrophin, many other studies on muscular dystrophy have been conducted for elucidation of the etiological gene and pathophysiology, and development of therapeutic methods.
[0004]
One of the autosomal recessive muscular dystrophy, Fukuyama-type congenital muscular dystrophy (hereinafter also referred to as FCMD), characterized as severe congenital muscular dystrophy with brain formation disorder or intellectual impairment ) This was first reported about 40 years ago (Fukuyama, Y., Paediatria Universitatis Tokyo, 4, 5-8 (1960)), and is described as “MIM253800” in the catalog of McKusick.
[0005]
The FCMD is one of the most common autosomal recessive diseases in Japan and is the second most common form of pediatric muscular dystrophy. The incidence of FCMD in Japan is 0.7-1.2 per 10,000 (Fukuyama, Y., et al., Brain Dev., 6, 373-390 (1984)), which is the incidence of DMD (Fukuyama, Y., et al., Brain Dev., 3, 1-30 (1981)).
[0006]
FCMD patients usually show weakness of the face and limbs and generalized muscle tone by 9 months of age, and joint contractures generally occur earlier than DMD patients. The motor dysfunction level of FCMD patients is more severe than DMD patients, and most patients cannot walk. In general, FCMD patients are bedridden before the age of 10 due to muscle atrophy and joint contracture that have progressed throughout the body, and many of them die by the age of 20. Other accompanying symptoms include severe intellectual decline (IQ is 30-50) and convulsive seizures with abnormal brain waves in about half (Fukuyama, Y., et al., Brain Dev., 3, 1-30 (1981)).
[0007]
The histopathological changes observed in skeletal muscle are similar to those of DMD patients.
[0008]
The most common and characteristic changes in the central nervous system are probably brain malformations due to neuronal migration disorders, including the cerebellar and cerebellar minor multicerebral gyrus, thick gyrus and aencephalic gyrus. Furthermore, hydrocephalus, fibrous thickening of the cerebral buffy coat, local adhesion of the left and right cerebral hemispheres and hypoplasia of the corticospinal tract are often observed (Fukuyama, Y., et al., Brain Dev., 3, 1 -30 (1981)). Therefore, analyzing and identifying the pathogenic genes for FCMD is useful in understanding the pathophysiology of muscular dystrophy in general, and in addition, the information provides important insights into brain formation and growth. It is considered to give.
[0009]
In such a situation, the present inventors have found that the locus of the gene causing FCMD is present in the long arm 31-33 region of chromosome 9 by means of a combination of homozygosity mapping and linkage analysis. (Toda, T., eta al., Nat. Genet., 5, 283-286 (1993)). The inventors have also determined that the FCMD locus is in the 5cM region between D9S127 and marker CA246 (D9S2111) by means of homozygous mapping and recombination mapping, Found a linkage disequilibrium between the FCMD locus and the microsatellite marker (D9S306) in this 5 cM candidate region, and the FCMD causative gene was present within 1 Mb around D9S306 on chromosome 9q31 (Toda, T., et al., Am. J. Hum. Genet., 55, 946-950 (1994); Toda, T., et al., Jpn. J. Hum. Genet., 40, 333- 334 (1995)).
[0010]
In addition, by comparing the strength of linkage disequilibrium, the location of the FCMD locus has been specified to a region of less than 100 kb including D9S2107, and it is clear that most current FCMD chromosomes are derived from one ancestor (Toda, T., et al., Am. J. Hum. Genet., 59, 1313-1320 (1996)), and more than 80% of FCMD chromosomes have founder haplotypes in the ~ 200 kb region ( D9S2105-D9S2170-D9S2171-D9S2107 (138-192-147-183), which are found not to be found on the chromosomes of normal individuals. A cosmid-aligned clone (Contig) containing the D9S2105, D9S2170, D9S2171 and D9S2107 loci has also been constructed and reported (Miyake, M., et al., Genomics, 40, 284-293 (1997)).
[0011]
However, the FCMD causal gene has not yet been identified, and its analysis and identification have been strongly desired in the field.
[0012]
[Problems to be solved by the invention]
The present invention has been developed in view of such circumstances, and an object thereof is to provide a Fukuyama type congenital muscular dystrophy causative gene (FCMD causal gene). In the present invention, the FCMD causal gene and its cDNA are collectively referred to as FCMD DNA.
[0013]
        Another object of the present invention is to provide a protein encoded by a FCMD causative gene.
[0020]
In addition, in this specification, the display by the abbreviation regarding an amino acid, a peptide, a base sequence, a nucleic acid, a restriction enzyme, etc. is the nomenclature by IUPAC and IUPAC-IUB or its definition, and "the description including a base sequence or an amino acid sequence etc. "Guidelines for the preparation of" (Japan Patent Office Coordination Division Examination Standards Office, March 1997).
[0021]
Further, the expression (C → T250) in the present invention means that cytosine (C) at the base number 250 position in the FCMD causative gene is point-mutated to thymine (T). Moreover, (del: 298-299) means that base numbers 298 and 299 in the FCMD causal gene are deleted. The base number and base position used in the present invention are described with reference to the base sequence of the FCMD causative gene shown in SEQ ID NO: 3 derived from a healthy human in both the mutant gene and the DNA fragment. The amino acid number is expressed based on the amino acid sequence of the FCMD causal protein shown in SEQ ID NO: 1.
[0022]
The term “DNA” is intended to include not only double-stranded DNA but also single-stranded DNA such as sense strand and antisense strand constituting the DNA, and the length is not limited at all. Accordingly, the DNA of the present invention includes double-stranded DNA containing human genomic DNA, single-stranded DNA containing cDNA (sense strand), and single-stranded DNA (antisense strand) having a sequence complementary to the sense strand. ), And any of their fragments.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
As a specific example of the FCMD causal protein of the present invention, for example, a protein consisting of the amino acid sequence shown in SEQ ID NO: 1 can be mentioned, which indicates the movement of the microsatellite marker D9S2170 of the long arm 31 of chromosome 9 of a healthy human subject. It is specified as a protein encoded by a gene (about 1383 bp) present in the immediate vicinity of the drug substance.
[0024]
As described in detail in Examples below, this FCMD causal protein is a pathogenic protein involved in the onset of FCMD and is thought to cause the onset of FCMD due to its dysfunction. It is thought to play an important role in the formation and growth of
[0025]
Thus, the provision of the FCMD causal protein and the gene encoding the same (FCMD causal gene) according to the present invention can be carried out in the pharmaceutical field such as elucidation, understanding and diagnosis, prevention and treatment of FCMD and its onset or disease state. It provides extremely useful information and means in basic research and its application fields related to brain formation and growth.
[0026]
For example, gene therapy for utilizing or expressing the FCMD causative gene of the present invention or administration of the FCMD causal protein of the present invention to a living body will be useful for the treatment of FCMD. In addition, detection of the expression of the FCMD-causing gene of the present invention or a product thereof (FCMD-causing protein) in an individual or tissue, detection of mutation or abnormal expression of the gene, etc. will be suitably used for elucidation and diagnosis of FCMD. .
[0027]
Hereinafter, the present invention will be described in more detail according to the embodiment.
[0028]
The FCMD causal protein of the present invention consisting of the amino acid sequence shown in SEQ ID NO: 1 has the following structural characteristics or characteristics:
(A) consisting of a sequence of 461 amino acids;
(B) having an estimated molecular weight of 53.6 kDa;
(C) has an estimated isoelectric point of 8.29;
(D) hydrophobic amino acid residues (Lys, Val, Phe, Ile and Met) account for 30.8% of the total amino acids;
(E) has one N-glycosylation estimation region;
(F) has four protein kinase C phosphorylation sites;
(G) has one tyrosine kinase phosphorylation putative site;
(H) has 5 N-myrist relation estimation sites;
(I) It has a signal sequence estimation region.
[0029]
(J) It has 0 or 1 transmembrane estimation region.
[0030]
Specifically, (e) the N-glycosylation estimation region is located at amino acid numbers 92 to 95 in the amino acid sequence shown in SEQ ID NO: 1 (the same applies hereinafter) (indicated by the dotted underline in FIG. 4). ). (F) Protein kinase C phosphorylation sites that can be phosphorylated by protein kinase C are located at serine residues at amino acid numbers 33 and 276 and at threonine residues at amino acid numbers 386 and 426 (FIG. 4). In symbol%). (G) The tyrosine kinase phosphorylation site that can be phosphorylated by tyrosine kinase is located at the tyrosine residue at amino acid number 252 (indicated by the symbol ^ in FIG. 4). (H) The N-myristole estimation site is located at the glycine residues at amino acid numbers 37, 39, 45, 300 and 380 (indicated by the symbol * in FIG. 4). (I) The signal sequence estimation region is located at amino acid numbers 1 to 21 (indicated by the solid underline in FIG. 4). It is also suggested that (J) the transmembrane region may not be present or may have amino acid numbers 288 to 306 (indicated by the underline in FIG. 4).
[0031]
According to database search (GeneBank, dbEST, SwissProt, PIR), the amino acid sequence of this FCMD causative protein is not similar to the amino acid sequence of a known protein, and the gene encoding it (shown in SEQ ID NO: 3). The nucleotide sequence of the FCMD causative gene having a nucleotide sequence) is hardly similar to a gene having a known function, and from these facts, it was confirmed that this FCMD causative protein and its DNA are completely novel. ing.
[0032]
  The DNA of the present invention is, for example, a DNA encoding the above-mentioned FCMD causal protein. More specifically, this is exemplified as a DNA having the base sequence shown in SEQ ID NO: 2 or 3, but it is particularly limited to these. ThingNo.
[0036]
Furthermore, the DNA of the present invention is exemplified by a specific example of the base sequence shown in SEQ ID NO: 2 or 3. This base sequence indicates a codon encoding each amino acid residue in the amino acid sequence (SEQ ID NO: 1). In view of the codon degeneracy, the DNA of the present invention is not limited thereto, and it is of course possible to have a base sequence in which any codon is selected in combination for each amino acid residue. The selection of codons can be in accordance with conventional methods, for example, the codon usage frequency of the host to be used can be considered (Ncleic Acids Res., 9: 43 (1981)).
[0038]
In the present invention, as described later, the FCMD causative gene was identified by screening a human cDNA library using a clone capable of detecting the region near D9S2170 as a probe, and gene mapping of the obtained clone. Based on the sequence information, DNA can be easily produced and obtained by general genetic engineering techniques (Molecular Cloning 2nd Ed., Cold Spring Harbor Laboratory Press (1989); Research Methods I, II, III ”, edited by the Japanese Biochemical Society (1986), etc.).
[0039]
Specifically, for example, an FCMD causative gene is obtained by preparing a cDNA library according to a conventional method from an appropriate source from which it is expressed, and using an appropriate probe or antibody specific to the FCMD causal gene from the library. It can be carried out by selecting the desired clone (Proc. Natl. Acad. Sci. USA, 78, 6613 (1981); Science, 222, 778 (1983), etc.). In the above method, examples of the origin of cDNA include human tissues such as human heart, brain, skeletal muscle or pancreas, lymphoblasts, etc., from which total RNA is isolated, mRNA is isolated and purified, cDNA Acquisition and cloning thereof can be carried out according to conventional methods. In addition, cDNA libraries are commercially available, and in the present invention, these cDNA libraries, for example, various cDNA libraries commercially available from Clontech Lab. Inc. can be used.
[0040]
A method for screening the FCMD causative gene of the present invention from a cDNA library is not particularly limited, and can be performed according to a usual method. Specifically, for example, for a protein produced by cDNA, a method for selecting a corresponding cDNA clone by immunoscreening using the protein-specific antibody, and a probe that selectively binds to the target DNA sequence was used. Examples include plaque hybridization, colony hybridization, and combinations thereof.
[0041]
The probe used here generally includes a DNA sequence chemically synthesized based on the information on the base sequence of the FCMD causative gene of the present invention, but the already acquired gene itself and fragments thereof are also included. It can be suitably used.
[0042]
In obtaining the FCMD causative gene of the present invention, a DNA / RNA amplification method by PCR (Science, 230, 1350-1354 (1985)) can be preferably used. Especially when it is difficult to obtain a full-length cDNA from a library, RACE (Rapid amplification of cDNA ends; Experimental Medicine, 12 (6), 35-38 (1994)), especially 5'-race. The (RACE) method (Frohman, MA, et al., Proc. Natl. Acad. Sci., USA, 8, 8998-9002 (1988)) is preferably used. Primers used in adopting such a PCR method can be appropriately set based on the sequence information of the gene of the present invention clarified by the present invention.
[0043]
It should be noted that isolation and purification of the amplified DNA / RNA fragment can be carried out in accordance with a conventional method, and specific examples include gel electrophoresis.
[0044]
Further, the chemical synthesis of DNA and the modification means using the FCMD causative gene are as described above, and the desired DNA of the present invention can be obtained by following these conventional methods.
[0045]
The base sequence of the FCMD causal gene or DNA of the present invention obtained above can be determined according to a conventional method. Specific examples include the dideoxy method (Proc. Natl. Acad. Sci. USA, 74, 5463-5467 (1977)) and the Maxam-Gilbert method (Method in Enzymology, 65, 499 (1980)). For convenience, a commercially available sequence kit or the like may be used.
[0046]
According to the use of the DNA of the present invention, by using a general genetic engineering technique, the encoded product containing the FCMD causative protein can be easily and stably produced in large quantities. Accordingly, the present invention also includes a vector (expression vector) containing the DNA of the present invention, a host cell transformed with the vector, and a method for producing the protein of the present invention containing the FCMD causative protein by culturing the host cell. It is to provide.
[0047]
The production method is based on conventional gene recombination techniques (Science, 224: 1431 (1984); Biochem. Biophys. Res. Comm., 130: 692 (1985); Proc. Natl. Acad. Sci., USA., 80 : 5990 (1983) and the cited reference etc.).
[0048]
As the host cell, any of prokaryotes and eukaryotes can be used. For example, prokaryotic hosts widely used include commonly used ones such as Escherichia coli and Bacillus subtilis. In particular, those contained in Escherichia coli K12 strain can be exemplified. In addition, eukaryotic host cells include cells such as vertebrates and yeasts. For example, COS cells (Cell, 23: 175 (1981)) which are monkey cells and Chinese hamster ovary cells are used as the former. And its dihydrofolate reductase-deficient strain (Proc. Natl. Acad. Sci., USA., 77: 4216 (1980)), etc., and as the latter, Saccharomyces yeast cells are preferably used. It is not limited.
[0049]
Expression vectors in the case of using a vertebrate cell as a host usually include those having a promoter located upstream of the DNA of the present invention to be expressed, an RNA splice site, a polyadenylation site, a transcription termination sequence, and the like. This may further have a replication origin if necessary. Specific examples of the expression vector include pSV2dhfr (Mol. Cell. Biol., 1: 854 (1981)) carrying the SV40 early promoter. Further, specific examples of expression vectors in the case of using yeast cells as a host include, for example, pAM82 (Proc. Natl. Acad. Sci., USA., 80: 1 (1983)) having a promoter for the acid phosphatase gene. it can.
[0050]
When a prokaryotic cell is used as a host, a promoter and SD (Shine and Dalgarno) are used upstream of the DNA so that the DNA of the present invention can be expressed in the vector. An expression plasmid provided with a base sequence and an initiation codon necessary for initiation of protein synthesis (for example, ATG) can be preferably used. In general, pBR322 and its improved vector are often used as the vector, but the present invention is not limited to these, and various vectors can be used. The promoter is not particularly limited, and for example, tryptophan (trp) promoter, lpp promoter, lac promoter, PL / PR promoter and the like can be preferably used.
[0051]
As the expression vector for the DNA of the present invention, a normal fusion protein expression vector can also be preferably used. Specific examples of the vector include pGEX (Promega) for expression as a fusion protein with glutathione-S-transferase (GST). Etc.).
[0052]
The method for introducing the desired recombinant DNA (expression vector) into the host cell and the transformation method are not particularly limited, and various general methods can be employed. The obtained transformant can also be cultured according to a conventional method, and the target protein encoded by the DNA of the present invention is expressed and produced by the culture, and is accumulated in the cell, extracellular or cell membrane of the transformant. Or secreted.
[0053]
As the medium used for the culture, various media commonly used according to the employed host cells can be appropriately selected and used, and the culture can also be performed under conditions suitable for the growth of the host cells.
[0054]
The recombinant protein thus obtained (the protein of the present invention including the FCMD causal protein) can be separated and purified according to various separation operations utilizing its physical properties, chemical properties, etc., if desired (“Biochemical Data”). Book II ", pages 1175-1259, first edition, first edition, June 23, 1980, published by Tokyo Chemical Co., Ltd .; Biochemistry, 25 (25): 8274 (1986); Eur. J. Biochem., 163: 313 (1987)). Specific examples of the method include normal reconstitution treatment, treatment with a protein precipitating agent (salting out method), centrifugation, osmotic shock method, ultrasonic crushing, ultrafiltration, molecular sieve chromatography (gel filtration). , Adsorption chromatography, ion exchange chromatography, affinity chromatography, high performance liquid chromatography (HPLC) and other various liquid chromatography, dialysis methods, and combinations thereof.
[0055]
The protein of the present invention obtained as described above is useful, for example, in the pharmaceutical field as described above.
[0056]
The FCMD causal protein can also be used as an immunizing antigen for producing a specific antibody of the protein. The component used as the antigen here can be, for example, a protein produced in large quantities according to the above-mentioned genetic engineering technique or a fragment thereof. By using these antigens, desired antiserum (polyclonal antibody) and monoclonal antibody can be used. Antibodies can be obtained. The method for producing the antibody itself is well understood by those skilled in the art, and in the present invention, these conventional methods can be followed (Sequence Biochemistry Experiment Course “Immunobiochemistry Research Method”, edited by the Japanese Biochemical Society (1986). ) Etc.).
[0057]
For example, normal animals such as rabbits, guinea pigs, rats, mice, and chickens can be arbitrarily selected as immunized animals used for obtaining antiserum, and immunization methods and blood collection using the above antigens are also carried out according to conventional methods. it can.
[0058]
Monoclonal antibodies can also be obtained by preparing a fusion cell of a plasma cell (immune cell) of an animal immunized with the above immunizing antigen and a plasmacytoma cell, and selecting a clone that produces the desired antibody. Can be performed by culturing the clone. The immunized animal is generally selected in consideration of compatibility with plasmacytoma cells used for cell fusion, and usually mice, rats and the like are advantageously used. Immunization is the same as in the case of the above-described antiserum, and can be performed in combination with a normal adjuvant or the like as desired. The plasmacytoma cells used for the fusion are not particularly limited, for example, p3 (p3 / x63-Ag8) (Nature, 256: 495-497 (1975)), p3-U1 (Current Topics in Microbiology and Immunology). , 81: 1-7 (1978)), NS-1 (Eur. J. Immunol., 6: 511-519 (1976)), MPC-11 (Cell, 8: 405-415 (1976)), SP2 / Various myeloma cells such as 0 (Nature, 276: 269-271 (1978)), R210 (Nature, 277: 131-133 (1979)), etc. in rats, and cells derived therefrom can be used. .
[0059]
Fusion of the above immunocytes and plasmacytoma cells can be performed according to a known method in the presence of a usual fusion promoter such as polyethylene glycol (PEG) or Sendai virus (HVJ), and the desired hybridoma. Can also be carried out in the same way (Meth. In Enzymol., 73: 3 (1981); the above-mentioned course of secondary biochemistry etc.).
[0060]
In addition, a search for an antibody-producing strain of interest and single cloning are also carried out by conventional methods. For example, an antibody-producing strain is searched for by the ELISA method using the antigen of the present invention (Meth. In Enzymol., 70: 419). -439 (1980)), a plaque method, a spot method, an agglutination method, an uchterlony method, a radioimmunoassay and the like, and can be carried out according to various methods generally used for detection of antibodies.
[0061]
The target antibody is collected from the hybridoma thus obtained by culturing the hybridoma by a conventional method to obtain its culture supernatant, or by administering the hybridoma to a mammal compatible therewith to obtain it as its ascites. It is implemented by a method or the like. The former method is suitable for obtaining highly pure antibodies, and the latter method is suitable for mass production of antibodies. The antibody thus obtained can be further purified by ordinary means such as salting out, gel filtration, affinity chromatography and the like.
[0062]
The antibody thus obtained is characterized by having a binding property to the FCMD causal protein of the present invention, which can be advantageously used for purification of the FCMD causal protein and measurement or identification thereof by immunological techniques.
[0064]
Further, based on the sequence information of the FCMD causative gene revealed by the present invention, the present invention in an individual or various tissues can be obtained by using, for example, the DNA of the present invention having a part or all of the base sequence of the gene. Detection of gene expression can be performed.
[0065]
Such detection can be performed according to a conventional method. For example, RT-PCR (Reverse transcribed-Polymerase chain reaction; ES Kawasaki, et al., Amplification of RNA. In PCR Protocol, A Guide to methods and applications, Academic Press, Inc. , SanDiego, 21-27 (1991)), RNA amplification and Northern blot analysis (Molecular Cloning, Cold Spring Harbor Lab. (1989)), in situ RT-PCR (Nucl. Acids Res., 21: 3159-3166 (1993) ))) And in situ hybridization, etc., and can be carried out satisfactorily by the NASBA method (Nucleic acid sequence-based amplification, Nature, 350: 91-92 (1991)) and other various methods. .
[0066]
In the case of employing the PCR method, the primer used is not limited in any way as long as it is unique to the gene capable of specifically amplifying only the FCMD causative gene of the present invention, and is based on the sequence of the FCMD causative gene of the present invention. Can be set as appropriate. This can be the DNA of the present invention usually consisting of a partial sequence of about 15 to 30, preferably about 20 to 25 nucleotides, and the FCMD causal gene of the present invention consisting of a desired region set by the primer or a part thereof Can be used for amplification.
[0067]
Further, the probe for detecting the FCMD causal gene of the present invention is not limited as long as it is unique to the gene, and can be the DNA of the present invention comprising the FCMD causal gene of the present invention or a partial sequence thereof. Examples of the partial sequence include the DNA of the present invention consisting of a sequence of usually about 10 to 500, preferably about 100 to 500 nucleotides.
[0068]
Such primers and probes can be easily prepared by utilizing the FCMD causal gene of the present invention or chemically synthesizing according to the nucleotide sequence disclosed in the present invention using an automatic DNA synthesizer or the like.
[0070]
According to the measurement or detection of the expression of the FCMD causative gene by using the DNA of the present invention or the measurement or detection of the FCMD causative protein by using the above specific antibody, the expression level of the FCMD causative gene of the present invention in the subject or test tissue The abnormality can be grasped, which can be used and useful in diagnosis of FCMD.
[0071]
Furthermore, according to the present invention, it has been clarified that the onset of FCMD is associated with abnormal expression of the FCMD causative protein based on the mutation of the FCMD causative gene, and thus causes the malfunction of the FCMD causative protein. Detection of the presence of a mutant FCMD-causing gene having a mutation (detection of gene abnormality of the FCMD-causing gene) enables a desired diagnosis of FCMD.
[0073]
Here, the “mutation” means that the mutation of the FCMD-causing gene causes dysfunction of the FCMD-causing protein, that is, loss or reduction of the function of the protein and / or loss or reduction of expression of the protein. For example, the position and the degree of the mutation are not limited, and for example, the mutation can be located in either the translated region or the untranslated region, and this includes one or more (or several) nucleotides. Deletions, substitutions and / or additions (insertions) can be included.
[0074]
More specific examples of such a mutant FCMD causative gene include DNA that has been confirmed by the present inventor to cause dysfunction of the FCMD causal protein, that is, the base sequence shown in SEQ ID NO: 3 (i ) Substitution of cytosine to thymine at position 250, (ii) deletion at positions 298-299, (iii) one or more (or several) nucleotides between positions 5889 and 5890 Examples thereof include DNA having at least one kind of mutation.
[0075]
In the insertion mutation of (iii), the base sequence inserted between base numbers 5889 and 5890 and the length thereof are not particularly limited. For example, (TCTCCC)₄₁27 copies (tandem repeat) of a 49 bp sequence (5'-GGGAGGGAGGGTGGGGGGGGTCAGCCCCCCGCCTGGCCAGCCGCCCCATCC-3 '); SINE (short interspersed sequence) type human retroposon sequence; poly A additional signal (AATAAA); and poly (k) Can be mentioned.
[0076]
Detection of such a mutation in the gene of the subject, preferably, detection of at least one of the above mutations (i) to (iii) means a genetic abnormality of the FCMD causative gene in the subject, which is useful for diagnosis of FCMD. Very useful. Such a diagnosis is based on whether the subject has both a normal FCMD causative gene and a mutated FCMD causative gene (heterozygote), only a mutated gene (homozygote of a mutated FCMD causative gene), or only a normal FCMD causative gene. The determination of whether or not
[0077]
The detection of the gene abnormality in the FCMD causative gene is not limited in any way to its method or means, and various methods that are publicly known or can be obtained in the future can be widely adopted. For example, such detection methods include Southern hybridization and dot hybridization (both refer to Southern, EM, J. Mol. Biol., 98: 503-517 (1975), etc.), dideoxy base sequencing, or Various detection methods combined with DNA amplification techniques, such as PCR-RFLP (Restriction fragment length polymorphism), PCR-single chain conformation polymorphism analysis method (Orita, M. , et al., Proc. Natl. Acad. Sci. USA, 86: 2766-2770 (1989), etc.), PCR-SSO method (specific sequence oligonucleotide: PCR-specific sequence oligonucleotide method), PCR-SSO To illustrate the use of each method such as the allele specific oligomer method using dot hybridization method (allele specific oligomer: Saiki, RK, et al., Nature, 324: 163-166 (1986) etc.) In wear.
[0078]
For example, for the above-described mutations (i) to (iii), a more specific example of the detection method is as follows: a step of preparing a DNA fragment containing the mutation region and a base sequence of the DNA fragment Illustrated as a method comprising the steps.
[0079]
Preparation of a DNA fragment containing a mutated region from a test DNA can be performed by amplification according to the PCR method described above or a modified method thereof, or according to a conventional method such as restriction enzyme digestion of genomic DNA.
[0080]
The primers employed for the amplification of the DNA fragment are as described above, and are set so as to synthesize a DNA fragment having a certain base length having at least the region containing the mutation position. Preferably, it is desirable to design the sequence in the upstream region of the mutation position to be a detection target as a sense primer and the sequence in the downstream region of the mutation position as an antisense primer.
[0081]
The region (base length) of the DNA fragment synthesized here is not particularly limited, but is preferably set in consideration of the convenience of the subsequent analysis process of the base sequence of the DNA fragment. For example, the RFLP method is used for the analysis. When is adopted, it is preferable to set so as to give a difference in base length so that cleavage by a restriction enzyme can be confirmed. The term “DNA synthesis” as used herein is a concept that includes broadly extending and amplifying DNA having a sequence complementary to a specific DNA (sense strand, antisense strand) as a template.
[0082]
Analysis of the base sequence of the DNA fragment thus prepared can also be performed according to the various methods described above, including sequencing by sequencing. Preferably, the mutations of (i) and (ii) above are methods usually used for detection of point mutations such as RFLP method and allele-specific oligonucleotide method, and the mutation of (iii) A method using a probe specific to the insertion sequence can be preferably exemplified.
[0083]
In the examples described later, the detection of the mutation related to the point mutation (C → T250) in (i) is performed according to the PCR-RFLP method. The mutation position is located in exon 3 of the FCMD causative gene, and primers “ex3F” and “ex3R” for exon 3 amplification are employed for amplification of the region including this position. According to such primer setting, the desired region is provided as an amplified DNA fragment of 142 bp. The point mutation (C → T250) in (i) generates a specific cleavage site (AGCT) of the restriction enzyme AluI at base numbers 247 to 250. Therefore, the DNA fragment (142 bp) containing the mutation is subjected to digestion with restriction enzyme AluI to give three fragments of 113 bp, 25 bp and 4 bp. It is possible to detect it more easily than not showing. In addition, the produced | generated fragment thru | or DNA fragment can be confirmed as a specific band according to a conventional method.
[0084]
The RFLP method can be carried out by using a restriction enzyme site that has been generated or disappeared due to the mutation. However, when the restriction site cannot be recognized by the mutation according to the present invention alone, for example, a primer is used. It is also possible to artificially introduce a desired restriction enzyme site by making a mismatch in.
[0085]
In the detection of the mutation according to (ii) above (del: 298-299), primers (“ex4F” and “ex4R1” for amplifying a partial region of exon 4 containing the mutation position are used, The amplified DNA fragment is detected by directly sequencing (sequencing) the DNA fragment.
[0086]
In the detection of insertion mutation according to (iii) above, Southern hybridization using a probe capable of detecting the region using genomic DNA digested with an appropriate restriction enzyme that gives a fragment containing the mutation position, such as PvuII, etc. This mutation is detected. Any probe can be used as long as it can detect the region, such as the entire insert of cosmid clone cE6. Preferably, the probe detects an insertion sequence of about 3 kb related to the mutation, for example, the cE6. The 1.4 kb EcoRI fragment and the like can be exemplified. In the case of the above PvuII digestion, the corresponding DNA fragment can be confirmed by giving a band of about 8 kb when having the mutation (about 5 kb when there is no insertion mutation of about 3 kb).
[0088]
In addition, various operations that can be employed in these mutation detection methods, for example, DNA or DNA fragment synthesis, enzymatic treatment for the purpose of DNA cleavage, deletion, addition, or binding, DNA isolation, purification, replication, and selection , DNA fragment amplification, etc. can all follow conventional methods (see Molecular Genetics Experimental Method, published by Kyoritsu Publishing Co., Ltd. 1983; PCR Technology, Takara Shuzo Co., Ltd. published in 1990), etc. It can be appropriately modified and used.
[0089]
Furthermore, in the method for detecting a genetic abnormality of the present invention, the gene or DNA to be measured is not particularly limited. For example, blood, muscle biopsy, various autopsy tissues, villi containing FCMD-causing genes derived from humans And widely collected from biological samples such as amniotic fluid, biomaterial tissue, various cell lines.
[0090]
When detecting abnormalities of the FCMD causative gene as described above and performing FCMD genetic diagnosis based on such a method, a reagent kit containing a reagent for detecting a mutation of the FCMD gene as an active ingredient is used. Is preferred.
[0091]
Such a reagent kit is characterized by containing a reagent for specifically detecting the mutation according to the present invention as an active ingredient, and the active ingredient can be appropriately set according to the detection means employed. . Preferably, a reagent for preparing a DNA fragment containing a mutated region for detection, for example, a primer of the present invention designed to synthesize the DNA fragment using a DNA derived from a chromosome gene of the subject as a template, or the subject's A restriction enzyme for digesting the DNA to prepare a desired DNA fragment and / or a reagent for analyzing the base sequence of the DNA fragment to confirm the presence of a mutation, such as restriction enzymes Inventive probe or the like is contained as an essential component.
[0092]
Furthermore, the reagent kit of the present invention can be combined with one to several reagents depending on the detection. Examples of such combined reagents include dATP, dCTP, dTTP, dGTP, DNA synthase, RNA synthase and the like. Reagents can be selected and employed as appropriate according to the detection method employed. In addition, the reagent kit may contain an appropriate buffer solution, washing solution, and the like for the convenience of measurement.
[0093]
[Effect of the present invention]
The present invention provides the base sequence of the causative gene associated with Fukuyama type congenital muscular dystrophy and the amino acid sequence of the gene product. Further, the present invention relates to the onset mechanism of Fukuyama type congenital muscular dystrophy, that is, Fukuyama type congenital muscular dystrophy is caused by the deficiency of the gene product (FCMD causal protein) based on the abnormality of the FCMD causative gene of the present invention. This is the first elucidation of this.
[0094]
The detection method or diagnosis method of the present invention for discriminating abnormalities of the FCMD causative gene enables genetic and biochemical diagnosis of Fukuyama type congenital muscular dystrophy, particularly prenatal or carrier diagnosis, and its predisposition It is useful in predicting the course and prognosis.
[0095]
In addition, according to the genetic diagnosis using the FCMD causative gene of the present invention, Fukuyama type congenital muscular dystrophy and Walker-Warburg syndrome (Dobyns, WB, et al, Am. J. Med. Genet., 32, 195-210 (1989)), cerebrum-eye-dysplasia-muscular dystrophy syndrome (Towfighi, J., et al, Acta. Neuropath., 65, 110- 123 (1984)) and Fukuyama-type congenital muscular dystrophy-related diseases, including diseases that share the characteristics of Fukuyama-type congenital muscular dystrophy.
[0096]
In addition, the FCMD causal protein of the present invention is useful for preparing its specific antibody. Furthermore, such a specific antibody can be used for immunological measurement of FCMD causal protein expressed and produced in a living body. It is useful for diagnosis of sexual muscular dystrophy and elucidation of disease state.
[0097]
Furthermore, the information on the FCMD causative gene and its gene product in the present invention is important for knowing the onset mechanism of Fukuyama type congenital muscular dystrophy that causes complex damage to the nerves and brain, and the development of the nervous system and the brain. It is considered extremely important to understand the overall development.
[0098]
【Example】
Hereinafter, the contents of the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
[0099]
Materials and experimental methods in the examples are shown below.
[0100]
1. DNA samples from FCMD patients
Previous report (Toda, T., et al., Nat. Genet., 5, 283-286 (1993); Toda, T., et al., Am. J. Hum. Genet., 55, 946-950 (1994); 63 FCMD families of Toda, T., et al., Am. J. Hum. Genet., 59, 1313-1320 (1996)), plus 23 families, totaling 86 FCMD families The DNA samples were analyzed, and the DNA of 304 people, including 115 people with FCMD, was examined. FCMD was diagnosed based on standard diagnostic criteria (Fukuyama, Y., et al., Brain Dev., 3, 1-30 (1981)).
[0101]
2. Southern analysis
Membranes were prehybridized overnight at 65 ° C. in 10% SDS and 7% PEG containing 200 μg / ml sonicated human placental DNA. The cosmid was digested with the restriction enzyme NotI and the inserted DNA was separated. Probe DNA can be obtained using a commercially available kit (Megaprime labeling kit, Amersham).³²Radiolabeled with P-dATP, prehybridized in the same solution at 65 ° C. for 1 hour, and then hybridized to the membrane (Tokino, T., et al., Am. J. Hum. Genet., 48, 258-268 (1991)). Washing conditions were performed at 63-65 ° C. using 0.1 × SSC, 0.1% SDS.
[0102]
3. Sequence analysis
Sequencing was performed using a commercially available kit (PRISM ReadyReaction DyeDeoxy Terminator Cycle-sequencing Kit and AmpliTaq-FS, Perkin-Elmer) and analyzed with an ABI model 377 sequencer (Perkin-Elmer).
[0103]
Α³⁵This was also performed manually by the deoxy chain termination method using S-dATP. In this case, the sequencing reaction was electrophoresed on a 6% polyacrylamide denaturing gel and exposed to X-ray film.
[0104]
4). Northern analysis
RNA blots (Multiple-tissue Northern blot, Clontech) derived from various human tissues were purchased from Clontech and analyzed according to the company's manual.
[0105]
Total RNA from patient and normal lymphoblasts was isolated by acid phenol extraction (Trizolm, Gibco-BRL). Poly (A) + RNA (Poly (A) + RNA) was separated from total RNA by oligo dT chromatography (Oligo-dT Latex, Takara Shuzo) according to standard methods. Poly (A) + RNA (2 μg) was electrophoresed on a formamide-agarose gel and transferred to a membrane (Hybond N + membrane, Amersham). The membrane was washed at 50 ° C. using 0.1 × SSC, 0.1% SDS.
[0106]
5. PCR
PCR was performed using a commercially available polymerase (AmpliTaq polymerase, Perkin-Elmer).
[0107]
The long PCR assay for the founder insertion mutation consists of 500 ng of chromosomal DNA, 10 pmol of each primer, 1 × LA PCR buffer II (Takara Shuzo), each dNTP 0.4 mM (for dGTP, dGTP: deazaGTP = 1: 1), MgCl₂Of 50 mM reaction solution containing 2.5 mM and 2.5 units of polymerase (EX Taq polymerase, Takara Shuzo).
[0108]
Samples were incubated in a DNA thermocycler (GeneAmp 9600, Perkin-Elmer) under the following conditions:
94 ° C for 1 minute
10 cycles of 98 ° C for 10 seconds and 68 ° C for 20 minutes
20 cycles of 98 ° C for 10 seconds, 68 ° C for 20 minutes and 20 seconds each cycle
6). SSCP analysis
Amplification of the template DNA was performed using intron primers ex3F and ex3R for exon 3, and intron primer ex4F and exon primer ex4R1 for exon 4.
[0109]
ex3F: 5'-GTTGCATGCTGGACTTTGAA-3 '
ex3R: 5'-CATAAAGCACTTGGTAAAGGGC-3 '
ex4F: 5'-GACTGTTGTGTTGGCTTACTGG-3 '
ex4R1: 5'-GATACTGCAGTGCAAATGCAG-3 '
SSCP analysis was performed using a 10% polyacrylamide gel with or without 5% by volume of glycerol (Bannai, M., et al., Eur. J. Immunogenet., 21, 1-9). (1994)). Each sample (˜1 / 8 μl) was subjected to electrophoresis at −60 mAh, 10 ° C. or 20 ° C. in an apparatus (ResolMax, Atto) to separate single-stranded DNA fragments. Detection was carried out by the silver staining method, and PCR products showing band shifts were sequenced by the method described in 3 above.
[0110]
Example 1 Identification and analysis of FCMD causative gene
(1) A cosmid contig having marker loci D9S2105 and D9S2107 (Miyake, M., Genomics, 40, 284-293 (1997) )) Each cosmid clone (FIG. 1) was used as a probe to screen the genomic DNA of FCMD patients by Southern analysis.
[0111]
When the insert of cosmid clone cE6 containing D9S2170 was used as a whole as a probe, FCMD DNA digested with PvuII was found to have a new 8 kb band without a normal 5 kb band. (FIG. 2, left column). When the same DNA was digested with PstI or BglII instead of PvuII, one normal band disappeared and a new band larger than the disappeared band appeared (FIG. 2). These facts suggested that most genomic DNA of FCMD patients had a 3 kb fragment insertion sequence.
[0112]
When E6f3, a subfragment in the insert of cE6, was used as a probe, most patients showed an abnormal 8 kb band homozygously and the remaining patients showed both a normal 5 kb band and an abnormal 8 kb band. (Figure 3). In the figure, N represents the normal control, and F represents the result obtained from the FCMD patient. . A more detailed analysis confirmed the insertion of a 3 kb sequence in the 1.4 kb EcoRI fragment of cE6 in most FCMD patients (see FIG. 1).
[0113]
Of the 88 normal individuals who are not related to each other, only one had this insertion sequence heterozygously. This 1/88 ratio is in good agreement with the value reported for Japanese FCMD carriers (Fukuyama, Y., et al., Brain Dev., 6, 373-390 (1984). )).
[0114]
Furthermore, this insertion allele was found to segregate together with the FCMD founder haplotype 138-192-147-183 against D9S2105-D9S2170-D9S2171-D9S2107, which more than 80% of Japanese FCMD chromosomes have.
[0115]
These results suggest that the insertion of the 3 kb fragment into genomic DNA specific for FCMD patients is directly related to the FCMD phenotype, and even if it is polymorphic, the FCMD causative gene Suggests that they are very close to each other.
[0116]
(2) A human adult brain (caudate nucleus) cDNA library (1.4 × 10 6 clones) was screened using a 1.4 kb EcoRI fragment of cE6 capable of detecting the 3 kb insertion sequence as a probe, and poly ( 2.1 kb and 3.2 kb cDNAs with A) were obtained. The human adult brain cDNA library used was obtained from Dr. Triangle of Fukuoka University.
[0117]
Another cDNA library was screened using the inserted sequence at the 5 ′ end of this cDNA, and a parallel amplification of cDNA ends (RACE) experiment was carried out in parallel with this, so that another 13 clones (of which 7 One from a fetal brain cDNA library (Clontech) and the rest from a prepared heart cDNA for RACE).
[0118]
The RACE experiment was performed using a cDNA amplification kit (Marathon cDNA Amplification: Clontech) and a prepared cDNA derived from an adult heart (Marathon Ready cDNA: Clontech).
[0119]
By sequencing the total of 15 cDNA clones obtained, the full-length nucleotide sequences of continuous cDNAs were determined (FIGS. 4 to 5). The cDNA spans 7349 bp and has a 40 base poly (A) tail. The open reading frame (1383 bp) begins with a start ATG codon located at base numbers 112-114 and ends with a stop codon TGA located at base numbers 1495-1497. A stop codon is present in frame 42 nucleotides upstream of the start site, and common poly (A) addition sites are located at base numbers 4101, 4337, 6266, and 7327. The above two original cDNA clones obtained from a human adult brain cDNA library were obtained by poly (A) addition at the latter two sites (base numbers 6266 and 7327), It seems to correspond to the two bands on the blot (Figures 6 and 7).
[0120]
Northern blotting using a cDNA clone (II-5) containing a translation region as a probe reveals the presence of 6.5 kb and 7.5 kb transcripts in poly (A) mRNA prepared from a relatively wide variety of human tissues. became. Significant signals were obtained from heart, brain, placenta, skeletal muscle and pancreas, but not from lung, liver and kidney (FIG. 6). Furthermore, the transcript was also detected in cultured lymphoblasts (FIG. 7).
[0121]
The predicted protein product of the cDNA thus obtained (FCMD causative gene) consists of 461 amino acids, and is estimated to have a molecular weight of about 53.6 kDa and an isoelectric point of 8.29. The main hydrophobic amino acid residues (Lys, Val, Ile, Phe and Met) account for 30.8% of the total amino acids.
[0122]
(3) By searching the GenBank and dbEST databases using the BLASTN and FASTA sequence alignment algorithms, the FCMD causative gene was hardly similar to a gene having a known function. However, eleven cDNA terminal registration sequences (ESTs) derived from seven different cDNA libraries (fetal heart, brain, neuroepithelial cell line, embryo, parathyroid tumor, melanocyte and fibroblast) ( R57783, N41001, 45012, AA085522, AA328556, W44740, W60550, W37098, N35398, AA235981 and N94327), and R57873 matches the base number 95-318 region, and the other 10 ESTs are FCMD cDNA. Corresponded to the 3 ′ terminal sequence.
[0123]
Comparison of the predicted protein sequence with the predicted translation products of the SwissProt and PIR databases using BLASTP and FASTA and the GenBank, EMBL, DDBJ and PDB databases using TBLASTN There was no significant similarity. The C. elegans cosmids W02B3 and T07A5 (GenBank accession numbers: U22833 and Z48055) showed weak similarities.
[0124]
When the protein motif of FCMD protein was searched using the ProSite database (Bairoch, A., et al., Nucl. Acids Res., 25, 217-221 (1997)), one N-glycosylation site, 4 It was revealed to have one protein kinase C phosphorylation site, one tyrosine kinase phosphorylation site, and five N-myristolelation sites (FIGS. 4-5). According to a hydropathy calculation (Kyte, J., et al., J. Mol. Biol., 157, 105-132 (1982)), 16 hydrophobic regions were predicted. When the location of the protein was estimated using the PSORT program (Nakai, K., et al., Genomics, 14, 897-911 (1992)), the FCMD protein has an N-terminal signal having a cleavage site at codon 21. It was found to have a sequence but no transmembrane region.
[0125]
However, other programs, SAPS (Brendel, V., et al., Proc. Natl. Acad. Sci. USA, 89, 2002-2006 (1992)), SOSUI (Hirokawa, T., et al., Http: //www.tuat.ac.jp/-mitaku/adv_sosui/.) and TMpred (Hofmann, K., et al., Biol. Chem. Hoppe. Seyler, 374, 166 (1993)) Presence of one (amino acids 8-23), one (amino acids 6-27) and two (amino acids 8-28 and 288-306) transmembrane segments was predicted. If the “transmembrane” segment starting at amino acid 6 or 8 is interpreted as a signal sequence, the FCMD protein will have a signal sequence and zero or one transmembrane domain.
[0126]
Example 2 Mutation of FCMD causal gene-1 (insertion of 3 kb fragment)
(1) By comparing the cDNA and genomic sequence of FCMD, it was confirmed that an about 3 kb base sequence was inserted in the 3'-untranslated region of the FCMD causative gene (Figs. 1 and 4 to 5).
[0127]
The FCMD chromosome has this insertion sequence with high probability (125/144) by digesting restriction chromosomes (144) of chromosomal DNAs of FCMD patients who are not related to each other and performing Southern blotting analysis or long PCR method. I understood that. On the other hand, in a normal person, this insertion sequence was observed only in one chromosome out of 176.
[0128]
FIG. 8 shows the Mendelian inheritance of this insertion allele in a two generation FCMD family showing segregation with the 138-192-147-183 founder haplotype.
[0129]
(2) In order to examine the effect of this inserted sequence on the transcript of the FCMD causative gene, Northern blotting analysis of poly (A) mRNA isolated from patient's cultured lymphoblasts was performed.
[0130]
As can be seen from the results shown in FIG. 7, in the FCMD patient having the insertion sequence homozygously, the transcript of the gene causing FCMD was hardly detected. Also, in some FCMD patients that have heterozygous insertion sequences and other haplotypes, the amount of transcript was significantly lower. This result suggests that the insertion or other type of mutation in the FCMD causative gene causes a decrease in the transcription level of the FCMD causative gene and / or a decrease in mRNA stability, leading to loss of function of the FCMD causative protein. .
[0131]
(3) In order to specify the inserted DNA (3 kb), a clone containing the inserted sequence was recovered from a genomic library constructed from an FCMD patient having the inserted sequence homozygously.
[0132]
According to sequencing analysis, the inserted DNA fragment is 3062 bp long, (TCTCCC)₄₁A 27 bp copy (tandem repeat) of a 49 bp sequence (5'-GGGAGGGAGGGTGGGGGGGGTCAGCCCCCCGCCTGGCCAGCCGCCCCATCC-3 '); a SINE (short interspersed sequence) type human retroposon sequence; a poly A additional signal (AATAAA); Became. Moreover, since there was a “target site duplication” consisting of a series of repeats of AAGAAAAAAAAAATTGT at both ends, it was suggested that the insertion of this 3 kb fragment was caused by the retrotransposon mechanism.
[0133]
By homology search, the tandem repeat sequence in the inserted sequence is a human gene (Z11739) encoding the complement component C2, the genomic region (Z69654) near the Huntington's disease gene, and repeat sequences found in other sites. Almost matched.
[0134]
Example 3 FCMD causative mutation-2 (C → T 250 )
In Example 2, patients with heterozygous insertion chromosomes also showed a significantly lower amount of transcript (FIG. 7), but the inactivation mechanism in the FCMD chromosome without such a 3 kb insertion sequence. 4 patients were screened for exon and exon-intron boundary region sequences over the entire coding region by single-stranded conformation polymorphism (SSCP) analysis.
[0135]
As a result, a patient HM (lane 3 in FIG. 7 and the left panel in FIG. 9) having a 130-201-157-183 haplotype for the founder insertion sequence derived from the paternal and D9S2105-D9S2170-D9S2171-D9S2107 derived from the maternal The PCR product corresponding to exon 3 of the gene was found to have a shifted mobility. Sequence analysis of this PCR product revealed that cytosine (C) at base number 250, which is a maternal allele, was replaced with thymine (T), resulting in translation termination (from CGA). TGA, R47X: FIG. 10, left panel).
[0136]
Since this base substitution creates a new recognition site for the restriction enzyme AluI (AGCC to AGCT), it was used to perform PCR-RFLP analysis on other families of patient HM, and this point mutation could be It was confirmed to separate with the microsatellite haplotype. Furthermore, it was confirmed that other 5 families (YS, RM, AG, AT and AY) having the same haplotype have the same nonsense mutation (FIG. 11, left panel).
[0137]
Example 4 FCMD causative gene mutation-3 ( del: 298-299 )
In the same manner as in Example 3, a 2 bp deletion at base numbers 298 to 299 (codon 63) of the FCMD causative gene was found in patient TI, resulting in an incomplete termination at codon 75 due to a frameshift. (FIGS. 9 and 10, right panel).
[0138]
The patient's Japanese mother had an inserted chromosome, and an American father (a mixture of English and German) did not. The 2 bp deletion was present in the chromosome inherited from the paternal (FIG. 11, right panel).
[0139]
Example 5 Discussion
According to the present invention, a novel gene involved in the onset of FCMD, the FCMD causal gene, was provided.
[0140]
According to the haplotype analysis of the FCMD81 family, it is considered that the major mutation of the FCMD causative gene occurs in an ancestral chromosome having a 138-192-147-183 haplotype for D9S2105-D9S2170-D9S2171-D9S2107. The present invention has provided an important finding that the mutation is a 3 kb retrotransposon insertion in the 3 'untranslated region leading to loss of function of the FCMD causative gene.
[0141]
The mutation was found in 87% of the FCMD patient chromosomes tested.
[0142]
Northern blot analysis confirmed that the normal transcript of the FCMD causative gene was widely expressed in various human tissues. Notably expressed in heart, brain and skeletal muscle, FCMD patients together have congenital muscular dystrophy associated with brain malformations, and often fibrosis of the myocardium (Miura, K., et al., Acta. Path. Jpn. 37, 1823-1835 (1987)).
[0143]
The inserted DNA contains a tandem repeat of the 49 bp sequence often found in the human genome, and this repeat sequence is linked to a SINE type retroposon. Since this insertion sequence has a poly (A) addition signal and includes a long extended poly (A), the functional sequence is transcribed and incorporated into the FCMD gene by the mechanism of a retrotransposon. Conceivable. The existence of a 17 bp “target site duplication” supports this idea (Lewin, B., In Genes, VI, B. Lewin, ed. (Oxford: Oxford University Press), pp. 597-619 (1997)). Several examples of disease-related somatic cell or de novo germline retrotransporation integration are known in humans. These include hemophilia A (Kazazian, HH, et al., Nature, 332, 164-166 (1988)) and colon cancer (Miki, Y., et al., Cancer Res., 52, 643-645). (1992)), hemophilia B (Vidaud, D., et al., Eur. J. Hum. Genet., 1, 30-36 (1993)), neurofibromatosis type 1 (Wallace , MR, et al., Nature, 353, 864-866 (1991)) and breast cancer (Miki, Y., et al., Nat. Genet., 13, 245-247 (1996)). . FCMD is considered to be the first human disease in which tandem repeats inserted by retrotransposon mechanisms are transmitted from distant ancestors.
[0144]
This insertion (3 kb) in the FCMD causative gene leads to a marked decrease in the corresponding mRNA and is thought to lead to the FCMD phenotype due to its protein dysfunction. There are at least three possibilities that the insertion can lead to such a phenomenon:
(1) transcription efficiency is suppressed by the inserted sequence;
(2) Mutant FCMD RNA does not become a mature transcript;
(3) The stability of mRNA transcribed from the inserted allele varies.
[0145]
The development of myotonic dystrophy has been shown to involve an increase in the (CTG) repeat sequence in the 3 'untranslated region of the myotonin-protein kinase gene (Brook) , JD, et al., Cell, 68, 799-808 (1992)), this increased repeat sequence has been described as preventing poly (A) + RNA accumulation (Wang, J., et al., Hum Mol. Genet., 4, 599-606 (1995)). Also, the onset of Friedreich ataxia involves an abnormal increase in the (GAA) repeat sequence in the first intron of the gene encoding frataxin (Campuzano, V., et al., Science, 271, 1423 -1427 (1996)), and patients who are homozygous for this increased sequence are thought to have a marked decrease in the corresponding mRNA due to inhibition of transcriptional elongation (Bidichandani, SI). , et al., Am. J. Hum. Genet., 59 (suppl.), A246 (1996)). On the other hand, the 3 'untranslated region has been shown to affect the stability of mRNA (Sachs, AB, Cell, 78, 625-633 (1993)). For example, IRE (iron-responsive element) -binding protein binding to transferrin mRNA has been reported to stabilize mRNA containing a stem-loop structure that can bind this protein (Klausner, RD, Cell, 72, 19-28 (1993)). Therefore, the insertion of the 3 kb fragment into the 3'-untranslated region of the FCMD causative gene in the present invention may be possibly unstable by changing the secondary structure of mRNA.
[0146]
In addition, in some FCMD patients, a point mutation (deletion, substitution) that causes premature termination of the FCMD causative gene product has been found separately from the insertion mutation, and the expression level of the FCMD causative gene in the patient is It decreased to 10-20% of normal subjects.
[0147]
This strongly supports the conclusion that the FCMD causative gene of the present invention corresponds to the pathogenic gene of FCMD.
[0148]
The function of the FCMD causal protein according to the present invention can be considered from comparison with known information on the defective gene product of muscular dystrophy and the onset mechanism.
[0149]
Dystrophin, a defective gene product in Dushanne muscular dystrophy (DMD), is a large rod-like protein that exists directly under the muscle cell membrane, and is a huge oligomer complex (dystrophin-glycoprotein complex) composed of glycoproteins of the muscle cell membrane. ) (Ervasti, JM, et al., Cell, 66, 1121-1131 (1991)). Recent studies have shown that the loss of each component of this complex has disrupted a series of linkages from laminin α2 (melosin) present in the extracellular matrix to actin in the cytoskeleton directly under the muscle cell membrane. On the basis of various muscular dystrophy [DMD and Becker muscular dystrophy (Ohlendieck, K., Neurology, 43, 795-800 (1993)); α, β, γ and δ-sarcoglycanopathy (Roberds, sl, et al., Cell, 78, 625-633 (1994), Lim, LE, et al., Nat. Genet., 11, 257-265 (1995), Bonnemann, CG, et al., Nat. Genet., 11, 266-273 (1995), Noguchi, S., et al., Science, 270, 819-821 (1995), Nigro, V., et al., Nat. Genet., 14, 195-198 (1996) )); Melosin-deficient congenital muscular dystrophy (Helbling-Leclerc, A., et al., Nat. Genet., 11, 216-218 (1995)] has been shown to occur.
[0150]
On the other hand, in the muscle of FCMD patients, β-dystroglycan (Matsumura, K., et al., Lancet, 341, 521-522 (1993)), an dystrophin-binding glycoprotein, is immunostaining. And a decrease in immunostaining of laminin α2 chain, an extracellular matrix that binds α-dystroglycan, has been observed. The genes encoding these proteins include chromosome 3p21 (lbraghimov-Beskrovnaya, O., et al., Hum. Mol. Genet., 2, 1651-1657 (1993)) and chromosome 6q22-23 (Tryggvason, K., Cell Biol., 5, 877-882 (1993)), and their abnormal expression in FCMD muscle is considered to be a secondary change. However, abnormalities of FCMD muscle and brain basement membranes have also been observed by electron microscopy (Nakano, I., et al., Acta. Neuropathol., 91, 3131-321 (1996); Ishii, H., et al., Neuromuscul. Disord., 7, 191-197 (1997); Yamamoto, T., et al., Ultrastruct. Pathol., 21, 355-350 (1997); Yamamoto, T., et al., Brain Dev., 19, 35-42 (1997)).
[0151]
From these findings, the presence of a signal sequence and zero or one transmembrane region in the FCMD causative protein indicates that the FCMD causal protein is present in the extracellular matrix or the muscular plasma membrane, It suggests that it interacts with a huge complex surrounding the interior. Several putative phosphorylation sites also suggest that the FCMD causal protein binds to one or more other proteins and is phosphorylated.
[0152]
Furthermore, FCMD is known to be accompanied by brain malformation (brain dysplasia), so-called small multibrain gyrus, which is attributed to a defect in neuronal migration (Takada, K., et al ., J. Neuropathol. Exp. Neurol., 43, 395-407 (1984)). For this reason, the FCMD causal protein of the present invention seems to play an important role in nerve development, particularly migration of nerve cells. The mouse mutant “reeler” exhibits abnormal cerebral layer structure as a result of defects in neuronal migration during neurogenesis. The causative product “reelin” is a secreted glycoprotein with several structural properties characterized by extracellular matrix proteins, as well as the FCMD causal protein (D'Arcangelo, G., et al., Nature , 374, 719-723 (1995); D'Arcangelo, G., et al., J. Neurosci., 17, 23-31 (1997)).
[0153]
Therefore, information on the FCMD causative gene and its gene product in the present invention is important for understanding the development of the nervous system and the development of the entire brain, and elucidating their role in FCMD is important for the nerve and brain. It is considered to be extremely important in understanding the onset mechanism of FCMD that causes complex disorders.
[0154]
[Sequence Listing]

[Brief description of the drawings]
FIG. 1 is a schematic diagram of an FCMD candidate region on chromosome 9q31.
The position of the DNA microsatellite used for the linkage disequilibrium mapping method and the founder haplotype mapping method is shown. The FCMD causative gene was estimated to be located very close to the centromeric side of D9S2170.
The individual cosmids that make up the cosmid contig are shown as horizontal lines and the EcoRI site as a short vertical line. In the figure, N means NotI, and the position of the common mutation of ˜3 kb insertion is also shown (3-kb insertion). The spread of the FCMD cDNA on the genome is shown below the map with an arrow indicating the direction of transcription.
FIG. 2 to FIG. 3 are photographs in place of drawings showing Southern analysis (electrophoresis images) in FCMD patients.
FIG. 2 is a photograph replacing a drawing, showing the result (electrophoresis image) of genomic DNA digested with PvuII, PstI or BglII. Lanes 1-3 are patients who are homozygotes of 138-192-147-183 founder haplotypes; lanes 4 are patients who are heterozygotes of founder haplotypes; lanes 5 are normal controls. The entire insert of cosmid clone cE6 was used as a probe.
The band seen in normal controls disappeared in FCMD patients (arrow) and was observed to shift to ~ 8 kb (PvuII). Similarly, in the case of DNA digested with PstI or BglII, one of the normal bands disappeared, and a new band larger than the disappeared band appeared.
FIG. 3 is a photograph, instead of a drawing, showing the result (electrophoresis image) of Southern hybridization of PvuII digest using a partial fragment probe E6f3 in the insert of cE6. N indicates normal controls and F indicates FCMD patients.
FIG. 4 is a diagram showing the nucleotide sequence of FCMD cDNA and the amino acid sequence deduced from that sequence.
FIG. 4 is a view showing a nucleotide sequence (positions 1 to 2100) of FCMD cDNA and an amino acid sequence deduced from the sequence. The predicted hydrophobic signal sequence region and transmembrane main region are underlined (solid line), N-linked glycosylation sites are dotted, possible N-myristation sites are “*”, protein kinase C and tyrosine Serine / threonine and tyrosine residues that can be potentially phosphorylated by the kinase are indicated by "%" and "^", respectively. In addition, nucleotides (positions 250 and 298-299) related to the mutations revealed by the present invention are shown by hatching.
FIG. 5 shows the nucleotide sequence of FCMD cDNA (positions 2101 to 7381) following FIG. The used poly (A) addition site is indicated by “$”, and the founder insertion mutation site is indicated by an arrow.
FIG. 6 to FIG. 7 are photographs in place of drawings showing Northern analysis (electrophoresis images) of FCMD causative genes, respectively.
FIG. 6 is a photograph replacing a drawing, showing tissue-specific expression of FCMD mRNA in human tissue. RNA blots (Clontech) containing poly (A) + RNA (2 μg) derived from the 8 human tissues indicated were hybridized with FCMD cDNA probe (clone II-5, top) and β-actin cDNA probe (bottom). The result of soybean production is shown.
FIG. 7 is a photograph replacing a drawing showing the result of hybridization using the same probe as described above using an RNA blot containing poly (A) + RNA (2 μg) derived from lymphoblasts of FCMD patients and healthy controls. is there.
In FCMD patients with the insert sequence homozygous or heterozygous, the signal was almost zero or abnormally low.
FIG. 8 shows the Mendelian inheritance of an insertion allele in a two generation FCMD family showing the founder haplotype of 138-192-147-183 (electrophoresis image) and is a drawing instead of a photograph.
FIG. 9 to FIG. 11 are diagrams showing intra-family segregation of point mutations in FCMD patients, respectively.
FIG. 9 is a photograph replacing a drawing, showing a Southern analysis (electrophoresis image) showing intra-family separation of point mutations in FCMD patients (HM, TI). Southern analysis showed that patients HM and TI were heterozygous for the founder insertion allele inherited from the father and mother, respectively. Patient TI is the daughter of an American father and a Japanese mother.
FIG. 10 is a diagram showing the results of fluorescence sequence analysis for intra-family separation of point mutations in FCMD patients. Such analysis revealed that the patient's sequence had substitution (C → T250) and deletion (del: 298-299) mutations. Both of these mutations show incomplete translational stop (R47X and frameshift).
The sequence of the sense strand is shown.
FIG. 11 shows the results of confirming mutations in the HM family and other 5 families (YS, RM, AG, AT, and AY) having the same haplotype using the endonuclease AluI that cleaves DNA at the AGCT sequence site (electricity). It is a photograph replacing a drawing showing an electrophoretic image. The C → T250 mutant allele can be distinguished by AluI digestion because it has an AGCT sequence, whereas the normal allele is AGCC. In this case, the size of the normal PCR product is 142 bp, and the AluI digest of the mutant allele is divided into 113 bp, 25 bp and 4 bp fragments (small fragments could not be detected due to the presence of excess primers).
In the HM family, the mutant allele (without the insertion mutation) originated from the mother, and this mutation was inherited with a microsatellite haplotype. On the other hand, SSCP analysis showed that the 2 bp deletion in patient TI originated from a Western father (right, arrow).

Claims (4)

  A protein comprising the amino acid sequence shown in SEQ ID NO: 1.   DNA encoding the protein according to claim 1.   The DNA according to claim 2, comprising the base sequence represented by SEQ ID NO: 2.   The DNA according to claim 2, comprising the base sequence represented by SEQ ID NO: 3.

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