And God sent his only son to Earth, ERV9, to perform miracles in His name. Like bringing dead genes back to life.
A fun paper in PLOS Genetics describes an absolutely bizarre scenareo– A gene, IRGM, was ‘lost’ in the primate lineage like 50 million years ago. It turned into a pseudogene thanks to an Alu insertion, accumulation of a couple premature stop-codons, and a nice little frame-shift.
Well, about 24-20 million years ago, a retrovirus (ERV9) plopped its little butt upstream of IRGM, IRGM lost its stops and frameshift, and IRGM became functional again with a nice, shiny new ERV LTR as a promoter in gorillas, chimps, and humans!
Yay! Cause IRGM is a component of our innate immune system, specializing in whomping bacteria! Could be a handy weapon to have around!
No yay! Cause IRGM isnt the same IRGM that we had 50 million years ago. Its now got an ERV LTR for a promoter, it sits in a different part of the genome, and its surrounding genome landscape has changed dramatically– 33 retrotransposons (LINES/SINES/LTRs) have taken up residence upstream of IRGM!! Some people have a 20,000 base-pair deletion upstream from IRGM. This leads to expression of IRGM in wrong tissues at wrong levels, which could be a potential cause of Crohns disease.
But there is no doubt, this gene was dead, and was brought back to life, in part, though an ERV promoter. I cant complain about science journalists messing this up*. Its just good old fashioned cool 🙂
*I will, however, bitch about that “USEFUL JUNK?!? HURRR!” comment… Jesus. I mean, ERV9. 😛