The Retrobiome: the founding concept
Repeated retro-elements are fragments of ancient viruses that have been incorporated into mammalian genomes millions of years ago. Actually, their integration around 65 millions of years ago coincides with the time when rodent-looking mammalian ancestors have all of a sudden evolved into tremendous amount of phenotypic varieties.
These elements represent nearly half of the genome and until recently were considered as genomic junk, silenced through the course of evolution.
However there is a growing body of evidence that these elements could get activated: several groups have shown presence of LINE1 proteins in various cancers. Moreover it seems that activation of Retroelements increases genomic instability which in turn promotes tumor initiation and progression.
Recent work of Dr. Andrei Gudkov’s group at Roswell Park Comprehensive Cancer Center demonstrated that with aging amount of copies of repeated elements increases within genomes of humans, mice and dogs. Besides new integrations of repeated elements themselves, activity of retrobiome elevates genomic instability (introduces multiple mutations) which enforces development of cancers and multiple other age-related diseases. Therefore, activation of retrobiome serves as internal clock mechanism determining aging.
We hypothesize that this clock could be turned off through inactivation of the enzyme essential for activity of repeated elements: reverse transcriptase. Proof of concept was obtained in multiple experiments in mice, where inhibition of reverse transcriptase results in cancer prevention and life extension.