CN105492609A

CN105492609A - Method for CRISPR-Cas9 specific knockout of pig GGTA1 gene and sgRNA for specific targeted GGTA1 gene

Info

Publication number: CN105492609A
Application number: CN201580000475.3A
Authority: CN
Inventors: 蔡志明; 牟丽莎; 谢崇伟; 张军方; 陆赢; 刘璐; 高汉超; 陈鹏飞
Original assignee: Shenzhen Second Peoples Hospital
Current assignee: Shenzhen Second Peoples Hospital
Priority date: 2015-06-11
Filing date: 2015-06-11
Publication date: 2016-04-13
Also published as: WO2016197361A1

Abstract

The invention discloses a method for CRISPR-Cas9 specific knockout of a pig GGTA1 gene and sgRNA for a specific targeted GGTA1 gene. The target sequence of the sgRNA for the specific targeted GGTA1 gene on the GGTA1 gene is in accordance with the sequence arrangement rule of 5'-N(20)NGG-3', wherein N(20) represents 20 continuous bases, and each N represents A or T ot C or G; the target sequence on the GGTA1 gene is positioned at a junction of 5 exon coding areas and/or adjacent introns of the N-end of the GGTA1 gene; and the target sequence on the GGTA1 gene is unique. According to the method for CRISPR-Cas9 specific knockout of the pig GGTA1 gene via sgRNA, specific knockout of the pig GGTA1 gene can be rapidly and accurately realized with high efficiency, and the problems of long period and high cost for constructing the knockout of the pig GGTA1 gene can be effectively solved.

Description

The method of CRISPR-Cas9 specific knockdown pig GGTA1 gene and the sgRNA for selectively targeted GGTA1 gene

Technical field

The present invention relates to gene engineering technology field, particularly relate to gene Knockout field, be specifically related to the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene and the sgRNA for selectively targeted GGTA1 gene.

Background technology

Organ transplantation is the most effective treatment means for the treatment of organs debilitating diseases.Up to now, the patient in the whole world existing nearly 1,000,000 continues life by organ transplantation.Along with the progress of aging population and medical skill, need the patient carrying out organ transfer operation to get more and more, but the shortage of donor organ seriously constrain carrying out of organ transfer operation.For renal transplantation, China needs the patient carrying out renal transplantation to reach 300,000 every year, and the donation kidney that can be used for transplanting is no more than 10,000 examples, and most of patient dies from renal failure.Rely on after death organ donation can not meet the needs of organ transplantation.By other species genetic engineering modified, to provide the organ being appropriate to human implantation, become the main path solving non-human donor's organ shortage problem.

At present, evaluate according to biological safety, physiological function index, economy and rare species conservation etc. are many-sided, pig becomes ideal Xenogeneic organ source.But there is huge difference between pig and people, directly the organ transplantation of pig can be produced strong immunological rejection to people.Therefore, by genetically engineered, pig is transformed, to produce the organ being suitable for human implantation, become heteroplastic ultimate aim.

Immunologic research finds a kind of saccharide compound: α-1,3-galactose compounds (α-1,3-Gal) of the cell surface expression of pig.Its synthesis depends on alpha galactosides transferring enzyme 1 (alpha-galactosyltransferase1, GGTA1).Human cell has the GGTA1 gene of function owing to lacking, can not synthesize α-1,3-galactose compounds.And this compounds extensively exists in bacterium and non-primate.Can a large amount of antibody produced for α-1,3-galactose compounds under the stimulation of human body bacterium in vivo.If by the organ transplantation of pig to people, hyperacute rejection can be there is due to corresponding antibody, cause graft failure.Therefore, need α-1, the 3-galactose compounds molecule eliminating pig cell surface to reduce the immunogenicity of xenogeneic organ.And the knock-out pig GGTA1 gene of precise and high efficiency, be the committed step eliminating the immunological rejection that α-1,3-Gal causes.

At present, common gene Knockout comprises homologous recombination (HomologusRecombination, HR) technology, class transcriptional activation effector nuclease (TranscriptionActivator-LikeEffectorNuclease, TALEN) technology, Zinc finger nuclease (Zinc-FingerNuclease, ZFN) the short palindrome in the rule cluster interval of technology and latest developments repeats (ClusteredRegularlyInterspacedShortPalindromicRepeat, CRISPR) technology.Because recombination efficiency is low, (efficiency approximately only has 10 to HR technology ^-6), to the screening operation of mutant, very consuming time and poor efficiency, is substituted gradually.The cutting efficiency of TALEN technology and ZFN technology generally can reach 20%, but all needs to build the protein module that can identify particular sequence, and previous work is loaded down with trivial details time-consuming.The modular design of ZFN technology is comparatively complicated and have higher miss rate, and its application is limited.

CRISPR is that one comes from procaryotic acquired immune system, and the mixture that this system performs interference function is made up of protein C as and CRISPR-RNA (crRNA).This system finds that there is three types at present, and wherein Equations of The Second Kind Cas9 system composition is simple, is actively applied to genetically engineered field.Cas9 target cutting DNA is by two kinds of tiny RNA---crRNA (CRISPRRNA) and tracrRNA (trans-activatingcrRNA) realizes with the principle of target complement sequence identification.Two kinds of tiny RNA are fused into a RNA chain now, are called for short sgRNA (singleguideRNA), specific gene order can be identified, guide Cas9 albumen to cut.In eukaryote, there is non-homogeneous restructuring end after DNA is cut-off and connect, cause phase shift mutation, finally cause gene function to knock out.

Compared to above-mentioned 3 kinds of technology, CRISPR technological operation is simple, screening efficiency is high, can realize the cutting of accurate target.Therefore, knock out by CRISPR technology the screening efficiency that GGTA1 gene greatly can improve α-1,3-Gal deletion cells and genetically engineered pig.But the gordian technique difficult problem in this path designs and prepares the sgRNA of accurate target, because the target tolerance range height of gene depends on sgRNA target sequence, the sgRNA that success designs accurate target becomes the key technical problem knocking out goal gene, the invention is intended to solve this technical problem thus provides solid basis for knocking out GGTA1 gene.

Summary of the invention

The object of the present invention is to provide the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene and the sgRNA for selectively targeted GGTA1 gene.

According to a first aspect of the invention, the invention provides the sgRNA for selectively targeted GGTA1 gene in CRISPR-Cas9 specific knockdown pig GGTA1 gene, this sgRNA has following characteristics:

(1) target sequence of this sgRNA on GGTA1 gene meets the series arrangement rule of 5 '-N (20) NGG-3 ', wherein N (20) represents 20 continuous print bases, wherein each N represents A or T or C or G, and the target sequence meeting above-mentioned rule is positioned at positive-sense strand or antisense strand;

(2) target sequence of this sgRNA on GGTA1 gene is positioned at 5 exons coding districts of the N end of GGTA1 gene, or a part for target sequence is positioned at 5 exons of the N end of GGTA1 gene, rest part crosses over the boundary with adjacent intron, is positioned at adjacent intron;

(3) target sequence of this sgRNA on GGTA1 gene is unique.

As preferred version of the present invention, above-mentioned target sequence is the sequence shown in arbitrary sequence in SEQ ID NO:1 ~ 38.

As preferred version of the present invention, above-mentioned target sequence is the sequence shown in SEQ ID NO:1.

According to a second aspect of the invention, the invention provides the method using CRISPR-Cas9 specific knockdown pig GGTA1 gene, the method comprises the steps:

(1) 5 '-end of the target sequence of the sgRNA described in first aspect adds the sequence for the formation of sticky end, and synthesis obtains forward oligonucleotide sequence; The two ends of the complementary sequence that the target sequence of the sgRNA described in first aspect is corresponding add the suitable sequence for the formation of sticky end, and synthesis obtains reverse oligonucleotide sequence; By the forward oligonucleotide sequence of synthesis and reverse oligonucleotide sequence anneals, renaturation, form the double stranded oligonucleotide with sticky end;

(2) above-mentioned double stranded oligonucleotide is connected into the linearizing expression vector carrying Cas9 gene, obtain carrying the expression vector of sgRNA oligonucleotide containing respective target sequence and Cas9 gene, transform competent bacteria, Screening and Identification goes out correct positive colony, and positive colony is shaken to bacterium, extracts plasmid;

(3) the false type slow virus of sgRNA and Cas9 simultaneously carrying target GGTA1 gene is packed out with the expression vector of the above-mentioned sgRNA of carrying oligonucleotide and Cas9 gene, packaging plasmid and package cell line;

(4) use above-mentioned false type slow virus infection object cell, and cultivate further; Then collect infected object cell, with the gene fragment of its genomic dna above-mentioned target sequence for template amplification comprises, cut through sex change, renaturation and enzyme, that determines GGTA1 gene knocks out situation.

As preferred version of the present invention, above-mentioned expression vector is the carrier of sequence shown in SEQ ID NO:39.

As preferred version of the present invention, aforesaid method comprises the steps:

(1) 5 '-end of the target sequence of the sgRNA described in first aspect adds CACCG sequence, and synthesis obtains forward oligonucleotide sequence; 5 '-end of the complementary sequence that the target sequence of the sgRNA described in first aspect is corresponding adds AAAC sequence, 3 '-end adds C, and synthesis obtains reverse oligonucleotide sequence; By the forward oligonucleotide sequence of synthesis and reverse oligonucleotide sequence anneals, renaturation, form the double stranded oligonucleotide with sticky end;

(2) linearized vector that the expression vector lentiCRISPRv2 above-mentioned double stranded oligonucleotide being connected into sequence as shown in SEQ ID NO:39 obtains through BsmBI digestion with restriction enzyme, obtain the recombinant expression vector lentiCRISPRv2-GGTA1 carrying sgRNA oligonucleotide, transform competent bacteria, Screening and Identification goes out correct positive colony, and positive colony is shaken to bacterium, extracts plasmid;

(3) the false type slow virus of sgRNA and Cas9 simultaneously carrying target GGTA1 gene is packed out with above-mentioned expression vector lentiCRISPRv2-GGTA1, packaging plasmid and package cell line;

(4) use above-mentioned CRISPR false type slow virus infection object cell, and cultivate further; Then collect infected object cell, with the gene fragment of its genomic dna above-mentioned target sequence for template amplification comprises, cut through sex change, renaturation and enzyme, that determines GGTA1 gene knocks out situation.

As preferred version of the present invention, above-mentioned packaging plasmid is plasmid pLP1, plasmid pLP2 and plasmid pLP/VSVG; Above-mentioned packing cell is HEK293T cell.

As preferred version of the present invention, above-mentioned purpose cell is pig PIEC cell.

As preferred version of the present invention, above-mentioned with the gene fragment of its genomic dna above-mentioned target sequence for template amplification comprises, cut through sex change, renaturation and enzyme, that determines GGTA1 gene knocks out situation, is specially:

A () is to infect the genomic dna of the object cell of virus for template, the GGTA1 gene fragment of the target sequence of above-mentioned sgRNA is comprised, simultaneously with the genomic dna of the wild-type cell of same primers amplification uninfecting virus with the upstream and downstream primer amplification of GGTA1 gene;

B GGTA1 gene fragment that the above-mentioned amplification of () purifying is arrived, then in the future the GGTA1 gene fragment of the object cell of self-infection virus and GGTA1 gene fragment balanced mix, heat denatured, the renaturation from wild-type cell, form hybrid DNA molecule;

C () cuts the hybrid DNA molecule after renaturation with Cruiser enzyme;

D () electrophoresis detection digestion products, detects the GGTA1 gene knockout effect of target sequence mediation.

According to a third aspect of the invention we, the invention provides the recombinant expression vector lentiCRISPRv2-GGTA1 used in the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene, the sequence of the skeleton carrier of this recombinant expression vector is as shown in SEQ ID NO:39; Entrained target sequence as the target sequence of the sgRNA of first aspect, the target sequence shown in SEQIDNO:1 in preferred sequence table.

According to a forth aspect of the invention, the invention provides sgRNA as described in relation to the first aspect or the purposes of recombinant expression vector lentiCRISPRv2-GGTA1 in the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene described in the third aspect.

Of the present invention for CRISPR-Cas9 specific knockdown pig GGTA1 gene, successfully find the sgRNA of selectively targeted GGTA1 gene, sgRNA of the present invention is used in the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene, can fast, accurately, efficiently, knock-out pig GGTA1 gene specifically, effectively solve and build the technical problem that the GGTA1 gene knock-out pig cycle is long and cost is high.

Accompanying drawing explanation

Fig. 1 is the plasmid map of the vector plasmid lentiCRISPRv2 used in the embodiment of the present invention;

Fig. 2 is the plasmid map of the packaging plasmid pLP1 used in the embodiment of the present invention;

Fig. 3 is the plasmid map of the packaging plasmid pLP2 used in the embodiment of the present invention;

Fig. 4 is the plasmid map of the packaging plasmid pLP/VSVG used in the embodiment of the present invention;

Fig. 5 is the electrophoresis detection result figure of the gene knockout effect of digestion verification target sequence in the embodiment of the present invention, wherein M represents DNAMarker, Ctrl represents can not the target cutting effect of control sequence of efficient targeting GGTA1 gene, 1 represents that in table 1, No. 1 target sequence is to the target cutting effect of GGTA1 gene, 3 represent that in table 1, No. 3 target sequence is to the target cutting effect of GGTA1 gene, WT represents that the PCR primer Cruiser enzyme of the wild-type cell cut without virus infection and Cas9 cuts detected result, and arrow place represents the small segment obtained through the cutting of Cruiser enzyme;

Fig. 6 is the electrophoresis detection result figure based on the GGTA1 gene target cutting effect of 6 of sequence 1 PIEC cell monoclonals in the embodiment of the present invention, arrow place represents the small segment obtained through the cutting of Cruiser enzyme, wherein except No. 5 bands are more weak, 1,2,3,4, No. 6 cell all has and significantly cuts small segment;

Fig. 7 is the order-checking qualification result figure of 1,3 and No. 6 cell in Fig. 6, shows that sequence 1 effectively produces GGTA1 transgenation, wherein the sequencing result (Fig. 7 A) of No. 1 cell, comprises insertion mutation (1 sequence in Fig. 7 D) by analysis; The sequencing result (Fig. 7 B) of No. 3 cells, comprises deletion mutantion (3 sequences in Fig. 7 D) by analysis; The sequencing result (Fig. 7 C) of No. 6 cells, comprises deletion mutantion (6 sequences in Fig. 7 D) by analysis; Arrow in Fig. 7 A, B represents that sequence 1 mediates the theoretical cleavage site of Cas9 on GGTA1 gene, and WT represents wild-type sequence.

Embodiment

Below in conjunction with the drawings and specific embodiments, technical scheme of the present invention is described further.These the drawings and specific embodiments are not used for limiting the scope of the invention.If do not specialize, the conventional means that technique means used in embodiment is well known to those skilled in the art, is raw materials usedly commercial goods.

The test materials related in following examples and reagent: lentiCRISPRv2 plasmid is purchased from Addgene company, packaging plasmid pLP1, pLP2 and pLP/VSVG are purchased from Invitrogen company, package cell line HEK293T cell purchased from American Type culture collection warehousing (ATCC), PIEC cell is purchased from Chinese Academy of Sciences's cell bank, DMEM substratum, Opti-MEM substratum and foetal calf serum FBS are purchased from Gibco company, and Lipofectamine2000 is purchased from Invitrogen company.

Do not make the experimental methods of molecular biology illustrated in following examples, all carry out with reference to the concrete grammar described in " Molecular Cloning: A Laboratory guide " (third edition) J. Pehanorm Brooker one book, or carry out according to test kit and product description.

Recapitulative technical scheme of the present invention comprises following five parts:

One, the Choice and design of Susscrofa (pig) GGTA1 gene sgRNA target sequence

The sgRNA target sequence of 1.GGTA1 gene is selected:

Suitable 20bp oligonucleotide sequence is found as target sequence in GGTA1 gene extron subarea.

The sgRNA target sequence design of 2.GGTA1 gene:

Above-mentioned target sequence and complementary sequence are added joint respectively, forms forward oligonucleotide sequence and reverse oligonucleotide sequence.

Two, the CRISPR carrier of GGTA1 gene is built

1. synthesize above-mentioned forward oligonucleotide sequence and reverse oligonucleotide sequence, renaturation forms the double chain DNA fragment (i.e. double stranded target sequence oligonucleotide, also can be called double stranded oligonucleotide) with sticky end.

2. build CRISPR-sgRNA expression vector:

Above-mentioned double chain DNA fragment is built up to destination carrier (as lentiCRISPRv2, its plasmid map as shown in Figure 1), form the slow virus CRISPR carrier as lentiCRISPRv2-GGTA1.

Three, the false type slow virus of expressing GGTA1sgRNA is obtained

The false type slow virus of the CRISPR utilizing packaging plasmid, package cell line and slow virus CRISPR carrier to produce to express GGTA1sgRNA.

Four, infect object cell and detect GGTA1 gene knockout effect

1. slow virus infection object cell:

The false type slow virus of such as lentiCRISPRv2-GGTA1 is added object cell culture medium carry out infection and cultivate further.

2. detect GGTA1 gene knockout effect:

Collect object cell, take genomic dna as the gene fragment that template amplification comprises target sequence, cut through sex change, renaturation and enzyme, that determines GGTA1 gene knocks out situation.

Five, GGTA1 gene knockout is monoclonal selects and identifies

1., for there being the object cell mass determining to knock out effect, by dilution and Colony Culture, isolate the cell strain of some single cell source.

2. identify that monoclonal GGTA1 knocks out situation.

Describe technical scheme of the present invention and beneficial effect thereof by the following examples in detail.

The Choice and design of embodiment one, Susscrofa (pig) GGTA1 gene sgRNA target sequence

Target sequence determines the targeting specific of sgRNA and the efficiency of induction Cas9 cutting goal gene.Therefore, efficiently special target sequence Choice and design is the prerequisite building sgRNA expression vector.

1.GGTA1 the sgRNA target sequence of gene is selected

For GGTA1 gene, following principle should be followed on target sequence is selected:

(1) target sequence meeting 5 '-N (20) NGG-3 ' rule is found in GGTA1 gene extron coding region, wherein N (20) represents 20 continuous print bases, wherein each N represents A or T or C or G, and the target sequence meeting above-mentioned rule is positioned at positive-sense strand or antisense strand;

(2) 5 exons coding region sequences near N end are selected, target sequence can be positioned at 5 exons coding districts of the N end of GGTA1 gene, or a part for target sequence is positioned at 5 exons of the N end of GGTA1 gene, rest part crosses over the boundary with adjacent intron, is positioned at adjacent intron; The cutting of such coding region sequence can cause the function of GGTA1 gene to knock out, and the sequence of residual brachymemma can not be formed with the albumen of function;

(3) if there is multiple spliced body, then select in common exon coding region, 5 the exons coding region sequences held near N for GGTA1 gene Selection can meet this condition;

(4) online sequence analysis tools (http://crispr.mit.edu/) is utilized to analyze the homology situation of above target sequence in pig genome, give up the target sequence that there is remarkable homologous sequence, select further according to scoring, the target sequence selected is unique on GGTA1 gene.

Based on above principle, select the target sequence set shown in table 1.

The set of table 1 target sequence

Numbering	Sequence
		1	GCTGCTTGTCTCAACTGTAA
2	TGTTTTGGGAATACATCAAC
		3	CAACTGTAATGGTTGTGTTT
4	AACTGTAATGGTTGTGTTTT
		5	TCCAGAACAAAGAACCTTCT
6	ATCCAGAACAAAGAACCTTC
		7	TTCCGAGCTGGTTTAACAAT
8	TTTCCGAGCTGGTTTAACAA
		9	GGGGCTGGTGGTTTCCGAGC
10	TGAGCACTGCTGCCAACTTC
		11	GAGCACTGCTGCCAACTTCT

12	AAGTTGGCAGCAGTGCTCAG
		13	GAGAGCTTCCGCTAGTGGAC
14	AGACGCTATAGGCAACGAAA
		15	CAGAGGAGAGCTTCCGCTAG
16	GGATTAAACCAGTCCACTAG
		17	CTATAGCGTCTTCTTCTTCG
18	CACGAAGAAGAAGACGCTAT
		19	TGGTTATGGTCACGACCTCT
20	CTGGTTATGGTCACGACCTC
		21	AGGTCGTGACCATAACCAGA
22	TGACGGTTTTTGCTGTCGGA
		23	GCCAAACAGAAAATTACCGT
24	ATGGAAGGCTCCAGTGGTAT
		25	TAAGTGCCTTCCCATACCAC
26	CACGACCTCTGGGCGTTTCC
		27	GGTTTTTGCTGTCGGAAGGT
28	GCCCACGGTAATTTTCTGTT
		29	GATGGAAGGCTCCAGTGGTA
30	AAGGCTCCAGTGGTATGGGA
		31	TGCCAAACAGAAAATTACCG
32	GAAAATTACCGTGGGCTTGA
		33	GGCTTGACGGTTTTTGCTGT
34	AGCAAAAACCGTCAAGCCCA
		35	CGTGACCATAACCAGATGGA
36	TGGAGCCTTCCATCTGGTTA

37	GGCATAATAATTATCTAAGA
		38	AACCAGATGGAAGGCTCCAG

The sgRNA target sequence design of 2.GGTA1 gene:

(1) using lentiCRISPRv2 plasmid as expression vector, according to the feature of lentiCRISPRv2 plasmid, add CACCG sequence at 5 '-end of above-mentioned N (20) target sequence, form forward oligonucleotide sequence:

5’-CACCGNNNNNNNNNNNNNNNNNNNN-3’；

(2) add sequence at the two ends of the reverse complementary sequence of above-mentioned N (20) target sequence, form reverse oligonucleotide sequence:

5’-AAACNNNNNNNNNNNNNNNNNNNNC-3’；

Forward oligonucleotide sequence and reverse oligonucleotide sequence complementaryly can form the double chain DNA fragment with sticky end:

5’-CACCGNNNNNNNNNNNNNNNNNNNN-3’

3’-CNNNNNNNNNNNNNNNNNNNNCAAA-5’。

The sgRNA expression vector of embodiment two, structure GGTA1 gene

1. synthetic DNA Insert Fragment

(1) forward and the reverse oligonucleotide sequence of above-mentioned design is synthesized

Oligonucleotide sequence specifically can be synthesized according to the sequence provided by business-like company (as Invitrogen company).The present embodiment and following examples to have studied in table 1 No. 1 listed target sequence shown in sequence and knock out effect to GGTA1 gene.

The forward oligonucleotide sequence that No. 1 target sequence is corresponding and reverse oligonucleotide sequence as follows:

CACCGGCTGCTTGTCTCAACTGTAA(SEQIDNO：40)；

AAACTTACAGTTGAGACAAGCAGCC(SEQIDNO：41)。

By the forward of correspondence and reverse oligonucleotide sequence anneals, renaturation, form the double chain DNA fragment with sticky end.

Reaction system (20 μ L) is as follows:

Forward oligonucleotide (10 μMs): 1 μ L

Reverse oligonucleotide (10 μMs): 1 μ L

10×PCRbuffer：2μL

ddH ₂O：16μL

Above-mentioned reaction system is put into PCR instrument, and reacts by following program.

Response procedures:

95℃,5min；

80℃,5min；

70℃,5min；

60℃,5min；

50℃,5min；

Naturally room temperature is down to.

2. build sgRNA expression vector

(1) BsmBI digestion with restriction enzyme destination carrier lentiCRISPRv2 plasmid (its sequence is as shown in SEQ ID NO:39) is utilized.

Prepare according to following reaction system:

LentiCRISPRv2 plasmid: 1 μ g

10 × enzyme cuts buffer:2 μ L

BsmBI restriction enzyme: 2 μ L

Supplement ddH ₂o to cumulative volume 20 μ L

Endonuclease reaction system is placed in 37 DEG C of reaction 4h.

(2) electrophoretic separation cmy vector fragment

After enzyme cuts end, enzyme is cut mixture and is separated by agarose gel electrophoresis, select carrier segments (about 12kb) to cut, and reclaimed by DNA gel recovery post.

(3) double chain DNA fragment of synthesis and carrier main leaf section are carried out being connected also transformation of E. coli

The carrier segments that double chain DNA fragment renaturation obtained obtains with recovery carries out ligation, prepares according to following reaction system:

LentiCRISPRv2 carrier segments: 100ng

Double chain DNA fragment: 200ng

T4 ligase enzyme: 1 μ L

T4 ligation buffer:1 μ L

Supplement ddH ₂o to cumulative volume 10 μ L

Connection mixture is placed in 25 DEG C of reaction 2h.

Mixture transformation of E. coli DH5 α bacterial strain will be connected: in connection mixture, add 100 μ L bacillus coli DH 5 alpha competent cells, hatch 30min on ice after reaction terminates; Mixture is put into 42 DEG C of water-baths, after heat shock 90s, put into cooled on ice; Add 100 μ LLB substratum to mixture, 20min cultivated by 37 DEG C of shaking tables; Mixture is coated with AmpLB flat board, cultivates 14h for 37 DEG C.

(4) correct transformed clone is identified

Select some bacterium colonies from AmpLB flat board and carry out enlarged culturing, extraction plasmid carries out enzyme and cuts qualification.Select and may check order by correct clone, whether checking insertion sequence is correct.Conservation is carried out for correct lentiCRISPRv2-GGTA1 carrier cloning.

Embodiment three, acquisition express the false type slow virus of GGTA1sgRNA

1. material prepares

Amplification is extracting packaging plasmid pLP1, pLP2 and pLP/VSVG (purchased from Invitrogen, its collection of illustrative plates respectively as shown in Figure 2, Figure 3 and Figure 4) also; Amplification is extracting vector plasmid lentiCRISPRv2-GGTA1 also; Cultivate package cell line HEK293T cell (purchased from ATCC); DMEM substratum, Opti-MEM substratum and foetal calf serum FBS (purchased from Gibco); Lipofectamine2000 (purchased from Invitrogen); HEK293T cell cultures is in containing 5%CO ₂37 DEG C of culture environment in, substratum is the DMEM substratum containing 10%FBS.

2. transfection and virus packaging

First day: package cell line HEK293T is passaged to 10cmdish, about 30% degrees of fusion;

Second day: carry out transfection when HEK293T reaches 80% degrees of fusion according to following formula:

Preparating mixture 1, comprises:

lentiCRISPRv2-GGTA1：6μg

pLP1：6μg

pLP2：6μg

pLP/VSVG：3μg

Opti-MEM：500μL。

Preparating mixture 2, comprises:

Lipofectamine2000：30μL

Opti-MEM：500μL。

After leaving standstill 5min, mixture 1 and mixture 2 are mixed into transfection mixture, leave standstill 20min.

HEK293T substratum is changed to plasma-free DMEM medium, adds transfection mixture, be changed to the DMEM substratum of 20%FBS after 37 DEG C of cultivation 8h, continue to cultivate.

3. collection virus and preservation

3rd day: collect the HEK293T substratum supernatant containing virus after transfection 48h, after filtering with 0.45 μm of filter, packing, placed-80 DEG C of preservations.

Embodiment four, infect object cell and detect target sequence knock out effect

1. material prepares

Cultivate object clone pig hip arterial endothelium cells PIEC (purchased from Chinese Academy of Sciences's cell bank); DMEM substratum and foetal calf serum FBS (purchased from Gibco); The false type slow virus of lentiCRISPRv2-GGTA1 of different target sequence (sequence 1 and control sequence); PIEC cell cultures is in containing 5%CO ₂37 DEG C of culture environment in, substratum is the DMEM substratum containing 10%FBS.

2. slow virus infection object cell

First day: by object passage to 6 orifice plate, about 20% merges density.Each virus needs 6 holes, needs efficiency to contrast 6 holes simultaneously.

Second day: when object cell about 40% fusion density, add the false type slow virus supernatant of 1mLlentiCRISPRv2-GGTA1 and 1mLDMEM substratum.Efficiency contrast does not need to add slow virus.

3rd day: remove containing virus culture base after infecting 24h, change normal incubation medium into, add tetracycline to final concentration 2 μ g/mL, the efficiency control sample not infecting virus also adds tetracycline in contrast simultaneously, cultivates 48h.

3. cell infection Efficiency testing and cultivation

5th day: the efficiency compared with control cells do not infected should whole apoptosis (>95%) under the effect of tetracycline.Judge the efficiency of infection of cell according to the apoptosis situation infecting slow virus cell, usually can reach the efficiency of infection (apoptosis rate <10%) of more than 90%.Carry out infecting to reach suitable efficiency of infection after viral supernatants can being carried out concentrated or gradient dilution if desired.

After tetracycline screening, the apoptosis do not infected.Object cell is gone down to posterity again and is changed to ordinary culture medium and cultivate 48h.

4. detect GGTA1 gene knockout effect

(1) design upstream and downstream primer with the GGTA1 gene fragment that increases, wherein upstream and downstream primer sequence is as follows:

ctgtcagttcattgacttggctaatttgc(SEQIDNO：42)

caagctggtgacttggctgataactag(SEQIDNO：43)。

Object amplified fragments comprises sgRNA target sequence, and size is 362bp.Target sequence is no less than 100bp to the position at fragment two ends.

(2) collection unit divides object cell, uses promega genomic DNA kit extracting genomic dna.The genomic dna of the wild-type of extracting simultaneously object cell.

(3) take genomic dna as the GGTA1 gene fragment (comprising mutagenic samples and the wild-type samples of infection) that template amplification comprises target sequence.

Amplification reaction system (20 μ L) is as follows:

Upstream primer (10 μMs): 1 μ L

Downstream primer (10 μMs): 1 μ L

2×PCRMix：10μL

Genomic dna: 100ng

Prepare with above-mentioned reaction system, put into PCR instrument, and react by follow procedure.

Response procedures:

95℃,3min

95℃,30s

58℃,20s

72℃,20s

72℃,3min；

Wherein second step to the 4th step repeats 35 circulations.

(4) electrophoresis detection PCR primer reclaim purifying

(5) by heat denatured, the renaturation respectively of the DNA fragmentation after purifying, hybrid DNA molecule (comprising mutagenic samples and wild-type samples) is formed.

Reaction system is as follows:

Genomic PCR fragment: 200ng

5 × reaction buffer:2 μ L

Reaction system is totally 9 μ L

Response procedures:

95℃,5min；

80℃,5min；

70℃,5min；

60℃,5min；

50℃,5min；

Naturally room temperature is down to.

(6) add 1 μ LCruiser enzyme with the hybrid dna (comprising mutagenic samples and wild-type samples) after Cruiser enzyme cutting renaturation to the reaction mixture through sex change, renaturation, hatch 20min for 45 DEG C.

(7) electrophoresis detection digestion products, detects the GGTA1 gene knockout effect of target sequence mediation.

By the DNA fragmentation cut through enzyme with 2% sepharose carry out electrophoretic analysis, 100V, 25min.Determine the cutting situation of object fragment, judge the gene knockout effect of target sequence.

To the cutting identification of mutant DNA based on following principle: the cell through infecting can express sgRNA and Cas9.If genomic dna is cut by the Cas9 targeting proteins that sgRNA mediates, sudden change (wild-type becomes saltant type) can be introduced near cleavage site after repairing.Because wild-type and mutant sequences do not mate in this position, the wild-type DNA gone out as template amplification and mutant DNA just can produce annular (loop) structure of local through the hybrid molecule that refolding strategy is formed.And the latter can be cut off by the identification of Cruiser enzyme, causes hybrid DNA molecule to be cut into small segment.

As shown in Figure 5, control sequence (SEQIDNO:44GAATACATCAACAGCCCAGA in sequence table) can not produce cutting by efficient targeting GGTA1 gene to result, therefore small segment do not detected; PCR primer without the wild-type cell (WT) of virus infection does not detect small segment yet; Sequence 3 does not detect significantly cuts band, may due to can not efficient targeting target gene group DNA, or because target cutting efficiency lower being difficult to observe.Another kind of possible cause, if PIEC cell used exists polymorphism in this site in embodiment, is not inconsistent with standard sequence, and sequence 3 will be caused to fail efficient targeting.And sequence 1 can produce cutting by efficient targeting GGTA1 gene, the existence of small segment therefore detected, show that sequence 1 can as the target sequence of CRISPR-Cas9 specific knockdown pig GGTA1 gene.

Embodiment five, GGTA1 gene knockout are monoclonal to be selected and identifies

1. monoclonally to select (target sequence based on sequence 1)

(1) the object cell mass that part infects is gone down to posterity, get 100 unicellular 10cmdish that are transferred to and cultivate.

(2) cultivate after about 10 days, have a considerable amount of mono-clonal to grow into macroscopic level.

(3) independently clone by pipettor head scraping, cell is transferred in 24 orifice plates and cultivates, the corresponding clone in each hole.

(4) again after the cultivation of about a week, there is part to clone and grow to enough quantity, go to further qualification.

2. identify that monoclonal GGTA1 knocks out situation

(1) mono-clonal to be checked and wild-type cell is collected, respectively extracting genomic dna.

(2) according to preceding method, the GGTA1 gene fragment of increase respectively mono-clonal and wild-type cell, the gene fragment increased comprises sgRNA target sequence.

(3) the mono-clonal PCR fragment of equivalent is mixed with wild-type PCR fragment, heat denatured, renaturation, form hybrid DNA molecule.

(4) with the hybrid dna after Cruiser enzyme cutting annealing, 20min is hatched for 45 DEG C.

(5) whether electrophoresis detection digestion products, according to having cutting fragment determination mono-clonal whether effective sudden change (Fig. 6) occurs.

(6) the monoclonal PCR fragment of effectively suddenling change is checked order further, determine the catastrophe near target sequence.Qualification knocks out the mono-clonal (Fig. 7) of GGTA1 gene.

Result display shown in Fig. 6, based on the lentiCRISPRv2-GGTA1 false type slow virus infection object cell of the target sequence shown in sequence 1, detect from 6 mono-clonals of 100 unicellular middle random chooses through Cruiser enzyme restriction enzyme digestion and electrophoresis, wherein there are whole 6 mono-clonals (No. 5 mono-clonal bands are more weak) that cutting small segment can be detected, show that producer knocks out, gene knockout efficiency can reach 100%, illustrates that the target sequence shown in sequence 1 has the effect that very high target knocks out GGTA1 gene.

Fig. 7 shows and checks order further to the PCR fragment of 1, in Fig. 6 No. 3 and No. 6 single cell clones, determine the catastrophe near cleavage site, wherein Fig. 7 A is the sequencing result of the PCR fragment of No. 1 single cell clone, analysis package is containing a kind of insertion mutation (1 sequence in Fig. 7 D inserts a G Nucleotide).This shows to there occurs phase shift mutation, can clearly state successfully target and knock out GGTA1 gene.Contrast wild-type sequence finds, the G of insertion is positioned at theoretical cleavage site place.

Fig. 7 B is the sequencing result of the PCR fragment of No. 3 single cell clones, comprises deletion mutantion (3 sequences in Fig. 7 D) by analysis.Fig. 7 C is the sequencing result of the PCR fragment of No. 6 single cell clones, comprises another kind of deletion mutantion (6 sequences in Fig. 7 D) by analysis.The theoretical cleavage site of No. 6 single cell clones disappears after repairing.All there is frameshit in these two mono-clonal sequences, shows that GGTA1 gene generation target knocks out.Above insertion mutation and the existence of deletion mutantion show that sequence 1 can mediate GGTA1 gene generation target efficiently and knock out effect.

Above content is in conjunction with concrete embodiment further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, some simple deduction or replace can also be made.

Claims

1. using the sgRNA for selectively targeted GGTA1 gene in CRISPR-Cas9 specific knockdown pig GGTA1 gene, it is characterized in that:

(1) target sequence of described sgRNA on GGTA1 gene meets the series arrangement rule of 5 '-N (20) NGG-3 ', wherein N (20) represents 20 continuous print bases, wherein each N represents A or T or C or G, and the target sequence meeting described rule is positioned at positive-sense strand or antisense strand;

(2) target sequence of described sgRNA on GGTA1 gene is positioned at 5 exons coding districts of the N end of GGTA1 gene, or a part for target sequence is positioned at 5 exons of the N end of GGTA1 gene, rest part crosses over the boundary with adjacent intron, is positioned at adjacent intron;

(3) target sequence of described sgRNA on GGTA1 gene is unique.

2. the sgRNA for selectively targeted GGTA1 gene according to claim 1, is characterized in that, described target sequence is the sequence shown in arbitrary sequence in SEQ ID NO:1 ~ 38.

3. the sgRNA for selectively targeted GGTA1 gene according to claim 1, is characterized in that, described target sequence is the sequence shown in SEQ ID NO:1.

4. use the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene, it is characterized in that, described method comprises the steps:

(1) 5 '-end of the target sequence of the sgRNA described in any one of claim 1-3 adds the sequence for the formation of sticky end, and synthesis obtains forward oligonucleotide sequence; The two ends of the complementary sequence that the target sequence of the sgRNA described in any one of claim 1-3 is corresponding add the suitable sequence for the formation of sticky end, and synthesis obtains reverse oligonucleotide sequence; By the described forward oligonucleotide sequence of synthesis and reverse oligonucleotide sequence anneals, renaturation, form the double stranded oligonucleotide with sticky end;

(2) described double stranded oligonucleotide is connected into the linearizing expression vector carrying Cas9 gene, obtain carrying the expression vector of sgRNA oligonucleotide containing respective target sequence and Cas9 gene, transform competent bacteria, Screening and Identification goes out correct positive colony, and described positive colony is shaken to bacterium, extracts plasmid;

(3) the false type slow virus that the expression vector of sgRNA oligonucleotide and Cas9 gene, packaging plasmid and package cell line pack out sgRNA and Cas9 simultaneously carrying target GGTA1 gene is carried described in use;

(4) use described false type slow virus infection object cell, and cultivate further; Then collect infected object cell, with the gene fragment of its genomic dna described target sequence for template amplification comprises, cut through sex change, renaturation and enzyme, that determines GGTA1 gene knocks out situation.

5. the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene according to claim 4, it is characterized in that, described expression vector is the carrier of sequence shown in SEQ ID NO:39.

6. the method for the CRISPR-Cas9 specific knockdown pig GGTA1 gene according to claim 4 or 5, it is characterized in that, described method comprises the steps:

(1) 5 '-end of the target sequence of the sgRNA described in any one of claim 1-3 adds CACCG sequence, and synthesis obtains forward oligonucleotide sequence; 5 '-end of the complementary sequence that the target sequence of the sgRNA described in any one of claim 1-3 is corresponding adds AAAC sequence, 3 '-end adds C, and synthesis obtains reverse oligonucleotide sequence; By the described forward oligonucleotide sequence of synthesis and reverse oligonucleotide sequence anneals, renaturation, form the double stranded oligonucleotide with sticky end;

(2) linearized vector that the expression vector lentiCRISPRv2 described double stranded oligonucleotide being connected into sequence as shown in SEQ ID NO:39 obtains through BsmBI digestion with restriction enzyme, obtain the recombinant expression vector lentiCRISPRv2-GGTA1 carrying sgRNA oligonucleotide, transform competent bacteria, Screening and Identification goes out correct positive colony, and described positive colony is shaken to bacterium, extracts plasmid;

(3) the false type slow virus of sgRNA and Cas9 simultaneously carrying target GGTA1 gene is packed out with described expression vector lentiCRISPRv2-GGTA1, packaging plasmid and package cell line;

7. the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene according to claim 6, it is characterized in that, described packaging plasmid is plasmid pLP1, plasmid pLP2 and plasmid pLP/VSVG; Described packing cell is HEK293T cell.

8. the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene according to claim 6, it is characterized in that, described object cell is pig PIEC cell;

Described with the gene fragment of its genomic dna described target sequence for template amplification comprises, cut through sex change, renaturation and enzyme, that determines GGTA1 gene knocks out situation, is specially:

A () is to infect the genomic dna of the object cell of virus for template, the GGTA1 gene fragment of the target sequence of described sgRNA is comprised, simultaneously with the genomic dna of the wild-type cell of same primers amplification uninfecting virus with the upstream and downstream primer amplification of GGTA1 gene;

C () cuts the hybrid DNA molecule after renaturation with Cruiser enzyme;

9. the recombinant expression vector lentiCRISPRv2-GGTA1 used in the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene, it is characterized in that, the sequence of the skeleton carrier of described recombinant expression vector is as shown in SEQ ID NO:39; The target sequence of the entrained sgRNA of target sequence as described in any one of claim 1-3, the target sequence shown in SEQIDNO:1 in preferred sequence table.

10. the purposes of the sgRNA as described in any one of claim 1-3 or recombinant expression vector lentiCRISPRv2-GGTA1 according to claim 9 in the method for CRISPR-Cas9 specific knockdown pig GGTA1 gene.