Meeting Abstract
The Insulin and Insulin-like Signaling (IIS) network regulates cellular processes including growth, reproduction, and longevity. The top regulators of signaling in this network are the paralogous hormones IGF1 and IGF2. In mice and rats, IGF2 expression is turned off soon after birth, while IGF1 remains on throughout life. However, this is different from the expression patterns in humans and recent studies in reptiles that demonstrate IGF2 expression continues through adulthood. The lack of postnatal IGF2 expression in lab rodents has led to the hormone’s physiological effects and regulation of the IIS network during adulthood to be ignored. To test the extent to which IGF2 is expressed postnatally in amniotes, we quantify the gene expression of the IGF1 and IGF2 hormones across amniote lineages using two approaches. First we use quantitative PCR on liver cDNA at three life stages (embryonic, juvenile, and adulthood) to compare the expression of IGF1 and IGF2 across the lab reared house mouse, wild derived house mouse, wild deer mouse, zebra finch, house sparrow, eastern fence lizard, and brown anole lizard. Second, we mine adult liver transcriptomes for all amniotes that are publicly available in NCBI and quantify relative expression of IGF1 and IGF2. In contrast to the biomedical models, we find that IGF2 is expressed ubiquitously across adult sauropsids and in many mammals, often at a higher level than IGF1. These data provide a fundamental understanding of IGF2 expression patterns in amniotes and in doing so has identified a spotlighting effect bias due to the acceptance of knowledge from laboratory rodents as being the default. Further, we identify species that can be used to study the function of IGF2 across lifespan.
