KR19990040732A - Method of manufacturing human granulocyte colony stimulating factor - Google Patents

Abstract

The present invention relates to a method for producing a recombinant human granulocyte colony stimulating factor, such a production method using a T7 promoter as a promoter for regulating expression and by increasing the A + T content of the N-terminal region without the introduction of unnecessary amino acids E. coli Allows for high expression of the gene of rHuG-CSF.

Description

Method of manufacturing human granulocyte colony stimulating factor

The present invention relates to a method for producing human granulocyte colony stimulating factor (hereinafter referred to as hG-CSF). More specifically, the present invention relates to a method for preparing a plasmid which enables high expression of recombinant human granulocyte colony stimulator (hereinafter, rHuG-CSF) in E. coli using genetic recombination technology.

Factors commonly referred to as colony stimulating factor (CSF) (such as interleukins, EPO, M-CSF, GM-CSF, G-CSF, etc.) regulate the proliferation and differentiation of blood cells from progenitor stem cells. Acts as a function of [Nicola: NA Annu. Rev. Biochem. 58, 45-77 (1989)], wherein the granulocyte colony stimulating factor (G-CSF) is produced mainly by macrophage, activated T cells, fibroblasts and endothelial cells and from neutrophil colony proliferation and progenitor cells. Is known to play a role in differentiation into neutrophils and stimulation of activity of mature neutrophils (Nagata, S. in Handbook of Experimental Pharmacology: Vol 95, Springer-Verlag, New York, pp699-722).

In addition, the method for producing the hG-CSF gene is synthesized from the cDNA library of human vascular endothelial cells (CLONTECK Cat. No. HL1164b) with two types of synthetic DNA (Primer I: 5'-CTGCATATGACCCCCCTGGGCCCT-) 3 'and Primer II: 5'-CTGGGATCCTTATCAGGGCTG-3') was used to synthesize a gene encoding rHuG-CSF by PCR, and the sock end of the synthesized DNA was cut with Nde I and BamH I to Nde I and BamH. It was conjugated to pET-21b plasmid cut by I (Novagen Cat. No. 69762-1). As described above, E. coli BL21 (DE3) (see Stratagene Cat. No. 200131) is transformed with the above plasmid and expressed by isopropyl-β-D-thiogalactopyranoside (hereinafter referred to as IPTG). Induced rHuG-CSF was not observed. It was estimated that the expression of the gene was impossible due to the high G + C ratio of the structural gene encoding the N-terminal portion of the protein (Devlin et al., Gene 65:13 (1988)). Accordingly, there is a need for a method for producing a plasmid having a high expression rate such that the expressed rHuG-CSF can be easily observed.

Accordingly, an object of the present invention is to prepare the rHuG-CSF from E. coli by gene recombination technology, using the T7 promoter with strong transcription ability to reduce the A + T content of the N-terminal rHuG-CSF gene without introducing unnecessary amino acids. It is to provide a method for producing rHuG-CSF with high expression rate by increasing.

1 is a production diagram of plasmid pT7GCSF capable of expressing human granulocyte colony stimulator genes,

Figure 2 shows the nucleotide sequence of the human granulocyte colony stimulator gene produced by the present invention,

Figure 3 shows the amino acid sequence of the nucleotide sequence of the human granulocyte colony stimulator gene prepared by the present invention,

Figure 4 shows the Western blot pattern on the SDS-PAGE of the human granulocyte colony stimulator protein prepared by the present invention,

Figure 5 shows the reverse phase HPLC chromatogram of the final purified liquid of the human granulocyte colony stimulator prepared by the present invention.

The above object is, according to the present invention, in the method for producing a recombinant human granulocyte colony stimulator, the production of recombinant human granulocyte colony stimulator, characterized in that the production from E. coli using a plasmid vector whose expression is controlled by the T7 promoter. By the method.

Here, it is preferable that the nucleotide sequence of the N-terminal region of the gene encoding the recombinant human granulocyte colony stimulating factor is 5'-ATGACACCTTTAGGACCT-3 '.

The present invention, in consideration of the above-described conventional problems in the process of developing a new primer synthesis method to increase the A + T content of the 5 'terminal without changing the amino acid, the newly synthesized primer Ia (5'-CTGCATATGACACCTTTAGGACCT-3 ') And primers II to develop a method for synthesizing the gene of the present invention by PCR, the expression of the rHuG-CSF was confirmed by cloning the gene by the above method.

As a promoter of the plasmid used in the present invention, a pET-21b plasmid vector having a T7 promoter derived from a T7 bacteriophage and a lac operator capable of regulating the T7 promoter beneath this promoter was used.

In more detail, the bacteriophage RNA polymerase has specificity for the T7 promoter sequence, which is rarely seen in E. coli. In addition, since the T7 promoter nucleotide sequence is not recognized by the E. coli RNA polymerase, when the expression is induced, only the target gene transcribed by the RNA polymerase of the bacteriophage is transcribed. However, despite the selectivity of the T7 RNA polymerase to the T7 promoter, the protein of interest is often partially expressed. In order to solve this problem and allow more precise control of expression, a host was introduced with a lac operator and a lac I ^q gene introduced for effective blocking of T7 RNA polymerase. At this time, when the expression is induced by IPTG, a large amount of T7 RNA polymerase of the host cell is expressed and expression of the target gene is achieved.

Hereinafter, the present invention will be described in detail through the following examples.

Example 1 (Preparation of hG-CSF Gene)

Two synthetic DNA primers (Primer Ia: 5'-CTGCATATGACACCTTTAGGACCT-3 'and Primer II: 5') modified from the nucleotide sequence of the hG-CSF gene from the cDNA library of human vascular endothelial cells (CLONTECH Cat. No. HL1164b). HG-CSF gene, a gene encoding rHuG-CSF, was synthesized by PCR using -CTGGGATCCTTATCAGGGCTG-3 '). After pure purification of the synthesized hG-CSF gene, the restriction end Nde I and BamH I were cut using the restriction enzymes Nde I and BamH I to enable conjugation with the T7 promoter of pET-21b. HG-CSF gene DNA fragment having a cleavage site was prepared.

Example 2 (Preparation of pT7GCSF Plasmid)

The plasmid pET-21b (obtained from Novagen) was digested with restriction enzymes Nde I and BamH I, and then the hG-CSF gene DNA fragment having the cleaved vector and the Nde I and BamH I cleavage sites made in Example 1 was transferred to T4 DNA. Conjugation was performed using ligase. The conjugated DNA mixture was transformed into E. coli NM522 competent bacteria and cultured in LB solid medium containing ampicillin. The plasmids were purified from the formed E. coli colonies and checked by restriction enzyme digestion or the like to select cloned strains, and the selected strains were cultured in an LB liquid medium containing ampicillin to obtain a large amount of cloned plasmids. This cloned plasmid was transformed into E. coli BL21 (DE3) (Stratagene) strain. Thus, the hG-CSF gene was controlled by the T7 promoter of plasmid pET-21b and plasmid pT7GCSF, which is an expression vector containing a transcription termination site, was constructed. 1 shows the preparation of the plasmid pT7GCSF.

Example 3 (Sequence Check of hG-CSF Gene)

The base sequence of the cloned hG-CSF gene was analyzed by reacting pT7GCSF purified using the Wizard Plus Minipreps kit (Promega Cat # A7510) with dideoxy chain termination. The base sequence of the obtained hG-CSF gene is Shuza, L. Base sequence of the hG-CSF gene as reported by M. (Souza, LM et al., 1986, Science 232: 61-65; Nagata, S. et al., 1986, Nature 319: 415-418) and the like. In comparison, the base was altered to lower the annealing of the resulting mRNA without altering the amino acid at the N-terminus. The entire base sequence of the hG-CSF gene is shown in FIG. 2, and the amino acid sequence obtained by decoding the base sequence is shown in FIG.

Example 4 Expression and Identification of hG-CSF Genes

E. coli BL21 (DE3) was transformed with the plasmid pT7GCSF prepared in Example 2 above, and the strain was transformed into 2X YT medium (16 g of bactotriptops, 10 g of yeast extract, 5) containing 50 µg / ml ampicillin. g of NaCl / 1 liter) was incubated at OD _600nm = 0.6 at 37 ° C, followed by 4 hours of incorporation of IPTG to a final concentration of 1 mM, followed by induction of rHuG-CSF. The cells were recovered by centrifugation of the cultured bacteria, and the cells were crushed to confirm the expression of the protein by SDS-PAGE [Lammli, Nature 227, 680-685 (1970)], and the antibody against rHuG-CSF was identified. It was confirmed that the expression protein was rHuG-CSF and the results are shown in FIG.

As a result of measuring the expression rate of rHuG-CSF on SDS-PAGE gel using a densitometer, it was found that the expression rate (ratio of expressed rHuG-CSF to E. coli total protein) was 36%. When rHuG-CSF expressed in the precipitate was found by centrifugation, it was confirmed that rHuG-CSF exists as an inclusion body.

Example 5 (Culturing of E. coli BL21 (DE3) transformed with plasmid pT7GCSF and purification of rHuG-CSF)

Strains were inoculated into 50 ml of 2X YT medium (16 g bactotrypton, 10 g yeast extract, 5 g NaCl / 1 liter) containing 50 μg / ml ampicillin, in a 37 ^° C. 250 rpm shake incubator. The seed was prepared by incubating for 16 hours.

On the other hand, a 5L fermentation tank containing a basal medium was installed, the temperature was 37 ^° C, agitation was 400 rpm, the inflow of air was 1 vvm, pH was maintained at 6.75-6.85 with ammonia water. The addition medium was connected and then 50 ml of the prepared seed was inoculated aseptically. Growth was examined by checking the concentration of OD ₆₀₀ and glucose at regular intervals during the incubation period and defoamer was added when foaming occurred. When the glucose concentration reaches 20 mg / L or less during the incubation, the addition medium is added. At this time, the glucose concentration is maintained at 10-30 mg / L, and the final 1 mM IPTG is added at OD ₆₀₀ = 30-40. After inducing expression, the consumption of glucose was stopped and cultured until no further growth of the production strain occurred.

The fermentation broth was collected and concentrated by a micro filter, and then the cells were incubated with a homogenizer, and the supernatant was recovered by centrifugation (10,000 x g, 30 min). The collected inclusion body was suspended in 1.5 L of distilled water, left for 2-3 hours and then washed by centrifugation to recover the precipitate.

Inclusion bodies were completely dissolved in 1 L of 8 M urea and 50 mM glycine buffer (pH 11, pH adjusted with sodium hydroxide solution). After centrifugation (10,000 x g, 30 min), the supernatant was taken and the amount of inclusion bodies was confirmed by protein quantification (Bradford method). 50 mM glycine solution was added to the inclusion body lysate so that the final concentration of the dissolved protein was 0.1-0.5 mg / ml and the urea concentration was 2 M, and the pH was adjusted to 9.0 with sodium hydroxide solution.

The pH adjusted lysate was slowly stirred at room temperature for 15 hours to perform protein refolding. A solution of protein refolding was adjusted to pH 5.5 to confirm the precipitate of the protein. The precipitate was removed by filtration with a 0.22 μm filter or centrifugation, the pH was adjusted to 3.0 with hydrochloric acid, and then concentrated to a protein concentration of 1-5 mg / ml using a filter that fractionated molecular weight 10 kD. The concentrated solution was purified using cation exchange resin. The eluted protein was analyzed by reverse phase HPLC, collected into one sample, and the pH was adjusted to 3.0 using hydrochloric acid.

The purified protein with ion exchange resin was purified using purified reverse phase HPLC (butyl silanated silica gel: C4). The fractionated protein was analyzed by reverse phase HPLC, and then collected into a sample and concentrated to a final protein concentration of 5-10 mg / ml using a membrane that fractionated a molecular weight of 10 kD. The concentrated protein was finally purified by gel filtration chromatography. The purified final protein was subjected to protein quantitation (absorbance at 280 nm) by reverse phase HPLC and spectrophotometer. Reverse phase HPLC chromatogram of final purified rHuG-CSF is shown in FIG. 5.

Example 6 (Confirmation of Biological Activity of rHuG-CSF by In Vitro Bioassay)

Test animals used healthy male mice, 6-15 weeks of age.

The culture medium was 100 ml of distilled water, 2.4 g of McCoy 5A powder medium, 0.44 g of sodium bicarbonate, 1.6 ml of the minimum essential medium (Sigma Cat. No. M7020), 2 ml of 100 mM sodium pyruvate solution, the minimum required medium. 0.8 ml of non-essential amino acid solution (Sigma Cat. No. M7145), 1.2 ml of 7.5% sodium bicarbonate, 0.8 ml of minimum essential medium (Sigma Cat. No. M6895), 2 ml of 20 mM glutamine solution, 4.2 ㎍ 0.4 ml of / ml serine solution, 0.4 ml of 8 µg / ml asparagine solution and 0.2 ml of 50 mg / ml gentamicin solution were added thereto, and distilled water was added to make the final volume 200 ml and filtered.

Culture medium was added to the hG-CSF standard (National Institute of Biological Standards and Control (NIBSC: UK), International Standard (1.0 x 10 ⁸ IU / mg)) to prepare a solution containing 200 active units in 1 ml and 96 Two-fold step dilution was carried out using a flat bottom microplate to prepare a standard liquid column. The culture medium was added to the purified hG-CSF sample (250 µg / ml) to dilute exactly 67,500 times and doubled using a 96 flat microplate. Step dilution was carried out to prepare a test column.

The femurs were taken from the test animals, the muscles on the femurs were cleaned well, and one end was cut with scissors. Rinse the bone marrow with a culture medium using a syringe and centrifuge at 1,000 RPM for 5 minutes to recover the cells, which are then suspended in 0.5 ml of culture medium, layered on a pre-prepared density gradient solution for Percoll, at 2,500 RPM. Centrifuged for 30 minutes. Fractions between the two marker beads were divided into four and the middle two fractions were recovered using the specific gravity 1.06 and the position of the density marker beads for 1.074 g / ml Percoll. The recovered cells were washed by centrifugation twice at 1,200 RPM for 6 minutes at 1,200 RPM, and the washed cells were suspended in culture medium. About 1-3 x 10 per T-prask⁷The cells were subdivided into pieces and allowed to stand for 2 hours in a 37 ° C incubator. After incubation, the non-adherent cells were pipetted and centrifuged at 1,200 RPM for 6 minutes to recover the cells, and the cell count was about 1.6x10 in 1 ml.⁶It was suspended in the culture medium so that the dog was used as a bone marrow cell suspension.

50 μl of the obtained bone marrow cell suspension was added to each hole of the flat microplate, and 50 μl of the prepared standard solution and 50 μl of the purified sample dilution solution were added to each hole. Incubate for 44 ± 4 hours in a 37 ° C incubator with a carbon dioxide concentration of 5%, suspend the cells well with a pipette, dispense 20 µl of ³ H-thymidine solution into each hole and incubate again for 4 hours under the same conditions. , washed three times the cells of each well with phosphate buffered saline solution collected in a glass filter by a cell harvester (cell harvester), and then the filter paper into a glass scintillation vial was added ssikeul (scintillation) 3 ㎖ liquid absorbed by the cell ³ H- The radioactivity (dpm) of thymidine was measured.

As a result of the above experiment, the calibration formula is obtained from the radioactivity (dpm) and the active unit obtained from the standard solution, and the active unit is obtained from the radioactivity (dpm) of the purified sample diluent falling within the radioactivity (dpm) range of the standard solution and multiplied by their average value and dilution ratio The active unit of was calculated.

Biological activity (inactivity) relative to the amount of protein can be calculated according to the following equation (1).

Inactivation results of the samples purified by the same method as shown in Table 1 below.

Sample name In vitro biological inactivity (1.0 x 10 ⁸ IU / mg) (95% confidence region) Purified rHuG-CSF 1.10 (87-139)

As described above, in preparing rHuG-CSF from Escherichia coli by the gene recombination technique according to the present invention, A + T of the rHuG-CSF gene N-terminus without introducing unnecessary amino acids using T7 promoter with strong transcription ability Increasing the content may provide a method for producing a high expression rate of rHuG-CSF.

Claims (2)

In the method for producing a recombinant human granulocyte colony stimulator, A method for producing a recombinant human granulocyte colony stimulator, which is prepared from Escherichia coli using a plasmid vector whose expression is controlled by a T7 promoter. The method of claim 1, A method of producing a recombinant human granulocyte colony stimulator, wherein the nucleotide sequence of the N-terminal region of the gene encoding the recombinant human granulocyte colony stimulator is 5'-ATGACACCTTTAGGACCT-3 '.