Molecular characterization of the HERV-W Env gene in humans and primates: expression, FISH, phylogeny, and evolution

抄録

We examined and characterized the human endogenous retrovirus (HERV-W) family in humans and primates. In silico expression indicated that 22 complete HERV-W families from human chromosomes 1-3, 5-8, 10-12, 15, 19, and X are randomly expressed in various tissues. Quantitative real-time RT-PCR analysis of the HERV-W env gene derived from human chromosome 7q21.2 indicated dominant expression in the human placenta. Within the complete or processed pseudo HERV-W of the human, chimpanzee, and rhesus monkey, several copies of the repeat sequences (SINE, LINE, LTR, simple repeat) were detected. Compared to other regions (5´LTR, Gag, Gag-Pol, Env, 3´LTR), the repeat family has mainly been integrated into the region spanning 5´LTR to Gag (1398 bp) or Pol (3242 bp) region. FISH data indicated that the HERV-W probe (fosWE1) derived from the gorilla fosmid library was clearly detected in the metaphase chromosomes of all primates (five hominoids, three Old World monkeys, two New World monkeys, and one prosimian), but was not detected in Tupaia. This data was also supported by molecular clock and phylogeny data using divergence values of complete HERV-W LTR elements. Further, the data suggested that the HERV-W family was integrated into the primate genome approximately 63 million years (Myr) ago, and evolved independently during the course of primate radiation.