Meeting Abstract

P1-35   -   Exploration of the mTOR pathways role in development in Austrofundulus limnaeus Peavy, M/C*; Romney, A/L; Podrabsky, J/E; Portland State University; Portland State University; Portland State University peavy@pdx.edu https://www.pdx.edu/podrabsky-lab/current-laboratory-members

The mammalian target of rapamycin signaling pathway, mTOR, is a master regulator of cell growth and differentiation. mTOR belongs to a family of kinases that modulates gene expression in response to cellular stress, such as DNA damage and nutrient deprivation. Research on the mTOR pathway as a molecular strategy that promotes survival under stressful or extreme conditions has gained clinical interest over the past two decades. Embryos of the annual killifish,Austrofundulus limnaeus, are capable of surviving anoxia by entering diapause; a reversible state of developmental and metabolic dormancy that has evolved for many in its phylogeny. Using potent chemical inhibitors of the mTOR molecular complexes, torin1 and rapamycin, we have explored the role of mTOR signaling as a mechanism that facilitates survival during embryonic diapause in A. limnaeus. Torin1, an inhibitor of both mTOR complexes 1 and 2, was added to embryonic growth media after fertilization (2-24nM). At concentrations of 8nM and higher, embryonic development was halted in a diapause-like state prior to embryo axis formation. Rapamycin, an inhibitor of mTOR complex 1, was also examined when added to growth media after fertilization. At concentrations between 10nM-200nM rapamycin did not induce a diapause phenotype. In addition, we examined whether the introduction of 1 α, 25-dihydroxyvitamin D3 (calcitriol) can rescue the embryos from diapause induced by torin1. We found that calcitriol, when introduced to rapamycin-treated embryos sped up development compared to control embryos yet had no impact on torin1-treated embryos. Future investigations to examine downstream effectors both with and without the use of inhibitors are essential to a deeper understanding of the mTOR pathway during embryonic diapause, and may be the key to the annual killifish’s survival during anoxia.