Endogenous retrovirus-related sequences provide an alternative transcript of MCJ genes in human tissues and cancer cells.

The MCJ gene is a member of the DNAJ family, and its transcriptional event is controlled by methylation of the CpG island. In our study, we found LTR33 and LTR7 elements provided an alternative transcript within the MCJ gene. To detect different expression patterns between the originally reported MCJ transcript and the LTR-related transcript, we performed a RT-PCR approach using various human tissues and cancer cells. The original MCJ transcript was detected in human tissues and cancer cells, whereas the LTR-related transcript was only revealed in some cancer cells (HCT106, MCF-3, TE-1, Hela, and CCHM). We also performed a PCR analysis to compare the insertion lineage of the LTR elements with the genomic DNAs of primates, indicating that those LTR33 and LTR7 elements of HERV-H have been integrated into the primate genome at different times. Taken together, we suggest that HERV-related elements trigger transcriptome diversification during primate evolution.