SICB 2020: A Cross-species comparison of IGF1 and IGF2 Expression in Amniotes

Cellular processes, including metabolism and longevity, are regulated by the insulin and insulin-like signaling network. This cascade of internal systems is regulated by two similar but unique hormones, IGF1 and IGF2. Expression of these hormones not only differs among species, but also varies throughout the lifespan of individuals. For example, in humans IGF1 and IGF2 expression remains on into adulthood. However, in rodents IGF2 expression is switched off shortly after birth; thus, IGF2 post-natal effects have largely been ignored because of the lack of expression in mice.

Ph.D. Candidate, Abby Beatty, of Dr. Tonia Schwartz’s lab at Auburn University, sought to address this imbalance by using the Cuban brown anole (Anolis sagrei) which, like humans, expresses IGF2 into adulthood. To do this, Abby first quantified gene expression of IGF1 and IGF2 hormones by using quantitative PCR on embryonic, juvenile, and adult A. sagrei liver cDNA. She compared this expression across a variety of taxa including, but not limited to, mice, zebra finches, and eastern fence lizards. Secondly, Abby mined adult liver transcriptomes for all amniotes in NCBI and quantified the expression of IGF1 and IGF2.

Brown anole (*Anolis sagrei)* (Photo Credit: Warner Lab, Auburn University)

She found that, in contrast to the mice used for many biomedical models, IGF2 is expressed in adult birds and reptiles and in many mammals. Abby speculates that our understanding of IGF expression is biased, with laboratory mice serving as a default for many human-mediated models, and warrants the use of other species to study the function of IGF2.