Mechanistic target of rapamycin complex 2 modulates FoxO1 phosphorylation in murine embryonic hearts during organogenesis.

MARIA LAURA LEONARDI, HUGO SATO, SABRINA ROBERTI, ALICIA JAWERBAUM, ROMINA HIGA.

Congreso; VIII Congreso de la Asociación Latinoamericana de Interacción Materno Fetal y Placenta (SLIMP); 2022

SLIMP

Objectives: The transcription factor Forkhead box protein O1 (FoxO1) has a role in heart development by being involved in the metabolism, oxidative stress, inflammation, and apoptosis of the cardiomyocyte. FoxO1 phosphorylation in Ser-256 induces its nuclear exclusion and inactivation. The mechanistic target of rapamycin (mTOR), a tyrosine kinase, functions as a nutritional sensor involved in cell growth, proliferation, and migration. It forms two complexes (mTORC1 and mTORC2), being serum and glucocorticoid-induced kinase 1 (SGK1) adownstream target of mTORC2. We have previously found a reduced P-FoxO1/total FoxO1 ratio that indicates increased levels of active FoxO1 in the embryonic heart from diabetic rats. Here, we aim to evaluate whether the mTORC2-SGK1 pathway is involved in FoxO1 phosphorylation.Methods: Diabetes was induced by streptozotocin administration to adult non-pregnant Wistar females (50mg/kg). On day 12 of pregnancy, embryonic hearts from diabetic and control rats were collected. For in vitro experiments, heart explants obtained from embryos of control rats at day 12 of pregnancy were incubated with a mTORC2 inhibitor (Torin2, 1μM) or vehicle for 3 hours. mTOR, phosphorylation of SGK1 in Ser-422, and phosphorylation of FoxO1 in Ser-256 were measured by Western Blot.Results: In the embryonic hearts from diabetic rats, mTOR, and P-SGK1, were found reduced (-67%, p