Jung Yi-Deun, Ha Hong-Seok, Park Sang-Je, Oh Keon-Bong, Im Gi-Sun, Kim Tae-Hun, Seong Hwan-Hoo, Kim Heui-Soo
Department of Biological Sciences, College of Natural Sciences, Pusan National University, Busan 609-735, Korea.
Mol Cells. 2013 Feb;35(2):99-105. doi: 10.1007/s10059-013-2289-6. Epub 2013 Feb 21.
Porcine endogenous retroviruses (PERVs) are integrated into the genomes of all pigs. Since some PERVs can also infect human cells, they represent a potential risk for xenotransplantation involving pig cells or organs. The long terminal repeat (LTR) elements of PERVs show promoter activity that can affect human functional genes; therefore, we examined these elements in this study. We detected several expressed LTRs in the NIH-miniature pig liver, among which we identified 9 different subtypes. When these LTRs were compared, distinct structures that contained several insertion and deletion (INDEL) events and tandem repeats were identified in the U3 region. The transcriptional activity of the 9 LTR subtypes was analyzed in the PK15 porcine cell line and in the HepG2 and Hep3B human liver cell lines, and transcriptional regulation was found to be different in the 3 cell lines. The D LTR subtype was found to have stronger promoter activity than all other types in 4 different human cell lines (HepG2, Hep3B, U251, and 293). Using computational approaches, the D type was shown to contain 4 transcription factor-binding sites distinct from those in the U3 regions of the other subtypes. Therefore, deletion mutants were constructed and examined by a transient transfection luciferase assay. The results of this analysis indicated that the binding site for the Hand1:E47 transcription factor might play a positive role in the transcriptional regulation of PERV LTR subtype D in human liver cell lines.
猪内源性逆转录病毒（PERVs）整合在所有猪的基因组中。由于某些PERVs也能感染人类细胞，它们对涉及猪细胞或器官的异种移植构成潜在风险。PERVs的长末端重复序列（LTR）元件具有启动子活性，可影响人类功能基因；因此，我们在本研究中对这些元件进行了检测。我们在NIH小型猪肝脏中检测到了几种表达的LTRs，其中鉴定出9种不同的亚型。对这些LTRs进行比较时，在U3区域发现了包含多个插入和缺失（INDEL）事件以及串联重复序列的不同结构。在PK15猪细胞系以及HepG2和Hep3B人肝细胞系中分析了9种LTR亚型的转录活性，发现这3种细胞系中的转录调控有所不同。在4种不同的人类细胞系（HepG2、Hep3B、U251和293）中，D LTR亚型的启动子活性比所有其他类型都更强。通过计算方法表明，D型含有4个与其他亚型U3区域不同的转录因子结合位点。因此，构建了缺失突变体并通过瞬时转染荧光素酶测定法进行检测。该分析结果表明，Hand1:E47转录因子的结合位点可能在人肝细胞系中PERV LTR亚型D的转录调控中发挥积极作用。
