Tame affairs: domesticated transposase and domestic pigs

Abstract

Long thought to be genomic junk, domesticated transposons have turned out to be an incredible source of new genes. Two studies—one this issue of EMBO reports—show that a domesticated hAT transposase is a transcriptional repressor of IGF2 that regulates muscle growth and has over 1,200 additional putative targets in the mammalian genome.

Figure 1

Possible evolutionary scenario for MGR/ZBED6. Before the divergence between mammals and birds about 300 million years ago, a transposase gene from a hAT transposon was domesticated into a new transcription factor, the molecular progenitor of mammalian ZBED genes. This gene was duplicated, leading to the formation of MGR/ZBED6 and other paralogues. The binding sites that allow gene regulation by ZBED proteins might be derived from the extremities of the ancestral transposon originally bound by the transposase and their dispersion might have occurred through transposition. During the selection of domestic pigs, the disruption of ZBED6-mediated regulation of IGF2 led to increased IGF2 expression, higher muscle mass and reduced fat deposition.