Gene targeting is a genetic technique that utilizes homologous recombination between an engineered exogenous DNA fragments with the endogenous genome of an organism. In domestic animal, gene targeting has provided an important tool for producing Knock-out pig for GGTA1 gene to use xenotransplantation. The frequency of homologous recombination is a critical parameter for the success of gene targeting. The efficiency of homologous recombination in somatic cells is lower than that in mouse ES cells. So the application of gene targeting in somatic cells has been limited by its low efficiency. Recently, knock-out rat and mouse was generated by introducing nonhomologous end joining (NHE)-mediated deletion or insertion at the target site using zinc-finger nucleases (ZFN). Therefore, the development of effective knock-out and knock-in techniques in domestic animal is very important in biomedical research. In this present study, we investigated whether homologous recombination events occurs at cytidine monophospho-N-acetylneuraminic acid hydroxylase (CMAH) gene locus using ZFN in porcine primary fibroblast. CMAH-targeted ZFN DNA and mRNA were purchased from SIGMA-Aldrich. CMAH neo targeting vector consists of the neomycin resistance gene as a positive selectable marker gene, 789 bp 5’ arm and 763 bp 3’ arm from Exon 8 of CMAH gene. For transfection, the targeting vector and ZFN DNA or mRNA were introduced into ear fibroblasts cells of Chicago miniature pig by electroporation. After selection of G-418, PCR analysis was performed using 213 colonies transfected with ZFN DNA or mRNA. As a result, 39 positive colonies were identified in colonies transfected with ZFN DNA or mRNA. To our knowledge, this study provides the first evidence that the efficiency of gene targeting using ZFN was higher than that of conventional gene targeting in the porcine fibroblast. These cell lines may be used in the production of CMAH knock-out for xenotransplantation.

Immunological rejection of the organ grafted onto a primate arises from two antibody mediated processes, hyperacute rejection (HAR) and acute humoral rejection (AHR). Functional ablation of α1,3-galactosyltransferase (GalT) and concurrently overexpression of complement regulatory proteins are known to inhibit HAR and AHR. In previous study, we reported that production of porcine male fibroblasts harboring a MCP expression cassette targeted to GalT locus. In this study, we constructed a different MCP expression cassette, in which the EF1α promoter regulates MCP expression and internal ribosome entry site-mediated neomycin resistance gene expression. Subsequently, this cassette was inserted between the left and the right homologous arms to target exon 9 of the GalT gene. Female fibroblasts were isolated from ear skin of 10 days old miniature pig, and used for nucelofection of the the construct for MCP expression at GalT locus. PCR analysis showed that four clones of forty neomycin resistant clones carry MCP expression cassette at exon 9 of the GalT gene. Two clones analyzed downregulated GalT expression, as determined by quantitative reverse transcriptase polymerase chain reaction. Flow cytometry analysis showed that MCP was efficiently expressed at the cell surface.

Acyl-CoA synthetase 4(ACSL4) is an arachidonate-preferring enzyme abundant in steroidogenic tissues and postulated to modulate eicosanoid production. The human and mouse ACSL4 gene are mapped on chromosome X. The female mice heterozygous for ACSL4 deficiency became pregnant less frequently and produced small litters, with 40% of embryos surviving gestation. In this study, we examined the regulation of ACS4 by estradiol-17β and progesterone (P4) in the human endometrial cancer cell line HTB-1B. ACSL4 mRNA was increased in a dose-dependent manner. Also, expression of ACSL4 gene was up-regulated in a time-dependent manner in HTB-1B cells. However, combined treatment with progesterone and estradiol-17β modestly decreased the levels of ACS4L mRNA as compared with the estradiol-17β and progesterone respectively. Overall, these results suggest that the ACSL4 gene is regulated by progesterone and estradiol-17β in the HTB-1B cells.

본 연구는 돼지 B-casein 유전자 위치에서 EGFP가 발현될 수 있는 knock-in 벡터를 구축하기 위하여 실시되었다. 돼지의 B-casein 유전자를 이용하여 knock-in 벡터를 구축하기 위해 돼지의 태아 섬유아세포로부터 B-casein 유전자를 동정하였고 EGFP, SV4O polyA signal을 동정하였다. Knock-in 벡터는 5' 상동 영역 약 5 kb와 3' 상동 영역 약 2.7 kb로 구성되어있으며, positive selection marker로 neor 유전자를, negative selection marker로 DT-A 유전자를 사용하였다. 구축된 knock-in 벡터로부터 EGFP의 발현을 확인하기 위하여 생쥐 유선 세포인 HC11 세포에 knock-in 벡터를 도입하였다. 그 결과 EGFP의 발현을 HC11 세포에서 확인하였다. 이와 같은 결과로서 이 block-in 벡터는 knock-in 형질전환 돼지를 생산하는데 사용될 수 있을 것으로 생각된다.

본 연구는 사람 H-transferase가 과발현하는 돼지 체세포주를 개발하는데 있다. 돼지 세포에 사람 H-transferase 유전자를 발현시키는 것은 이종간 장기 이식에 있어서 초급성 거부 반응을 방지하기 위한 한 가지 방법이다. 본 연구에서는 과발현 벡터를 구축하기 위하여 사람 H-transferase을 HepG2 세포로부터 동정하였으며, 이 유전자를 CMV promoter를 이용하여 발현할 수 있도록 포유동물 발현 벡터인 pRc/CMV 벡터에 삽입하였다. 또한, 돼지 산자의 귀 세포를 이용하여 체세포를 수립한 후 jetPEI DNA transfection reagent를 이용하여 벡터를 도입하였고, 300 μg/ml의 G418로 12일간 선별하였다. PCR을 이용하여 선별된 colony들을 분석한 결과, 벡터가 도입되었음을 확인하였고, RT-PCR을 이용하여 사람 H-transferase mRNA가 발현하는 것을 확인하였다. 본 연구에서 확립된 세포주는 사람 H-transferase가 과발현하는 형질 전환 돼지의 생산에 이용될 수 있을 것으로 생각된다.