Promoter activity analysis and methylation characterization of LTR elements of PERVs in NIH miniature pig

Abstract

The potential risk of porcine endogenous retrovirus (PERV) transmission is an important issue in xenotransplantation (pig-to-human transplantation). Long terminal repeats (LTRs) in PERV elements show promoter activity that could affect neighboring functional genes. The methylation status and promoter activities of 3 LTR structures (PERV-LTR1, LTR2, and LTR3 elements) belonging to the PERV-A family were examined using luciferase reporter genes in human liver cell lines (HepG2 and Hep3B). The PERV LTR3 element exhibited hypomethylation and stronger promoter activity than the other LTR elements in human liver cells. We also performed comparative sequences analysis of the PERV LTR elements by using bioinformatics tools. Our findings showed that several transcription factors such as Nkx2-2 and Elk-1 positively influenced the high transcriptional activity of the PERV LTR3 element.

Porcine Endogenous Retrovirus (PERV) – Molecular Structure and Replication Strategy in the Context of Retroviral Infection Risk of Human Cells

“…U3 appears to be the most heterogeneous region, with many binding sites for numerous transcription factors ( Scheef et al, 2002 ; Denner et al, 2003 ; Wilson et al, 2003 ; Ha et al, 2007 ; Park et al, 2010 ; Jung et al, 2013b ). In this region, there are direct repeated nucleotide sequences.…”

“…The increase in the number of repeats translates into an increase in the transcriptional activity of the retrovirus as well as an increase of the transcriptional activity of the neighboring host genes after the integration of the provirus ( Denner et al, 2003 ). The transcriptional activity of PERVs may also be controlled by DNA methylation and by the inhibition of histone acetylation ( Jung et al, 2008 , 2013b ; Park et al, 2010 ; Ha et al, 2012 ; Matousková et al, 2013 ; Wolf et al, 2013 ).…”

Porcine Endogenous Retroviruses in Xenotransplantation—Molecular Aspects

“…For xenotransplantation, consistent methylation of the U3 region seems important and suggests host suppression of retrovirus expression [103]. In their next studies, the authors analyzed the promoter activity of various PERV LTR elements by the characterization of DNA methylation and their sequences [104,105]. These authors also indicated that the differences in DNA methylation of LTRs seem to be specific for the cell or tissue type [104].…”

“…In their next studies, the authors analyzed the promoter activity of various PERV LTR elements by the characterization of DNA methylation and their sequences [104,105]. These authors also indicated that the differences in DNA methylation of LTRs seem to be specific for the cell or tissue type [104]. However, the heavy methylation in the majority of PERV 5’ LTRs was only revealed in porcine tissues.…”

Xenotransplantation literature update, July–August 2013

“…Jung et al. analyzed the promoter activity and methylation status of long terminal repeat (LTR) elements of porcine endogenous retrovirus (PERV) in NIH miniature pigs. LTR in PERV elements showed promoter activity that could affect neighboring functional genes.…”