FoxO1 in Embryonic Heart: Its Regulation by mTOR and Its Alteration by Maternal Diabetes

HIGA ROMINA; SATO HUGO; GATTI CINTIA R; ROBERTI SABRINA L; JAWERBAUM ALICIA

Congreso; Latin American DOHaD chapter 2020; 2020

The transcription factor FoxO1has a role in heart development by being involved in the metabolism, oxidativestress, endothelial dysfunction, inflammation and apoptosis of thecardiomyocyte. It phosphorylation in Ser 256 induces its nuclear exclusion andinactivation and this mechanism can be modulated by mechanistic target ofrapamycin (mTOR).Maternal diabetes affects theembryonic, fetal and perinatal development and programs metabolic andcardiovascular alterations in the adult offspring. We have recently reportedcardiovascular alterations related to the FoxO1 pathway in the adult offspringfrom diabetic rats.Angiopoietin-2 is an endothelialsecreted factor involved in vascular development and inflammatory processes.We aim to evaluate the in vitro regulation of FoxO1 phosphorylationby mTOR in the heart of the embryo and the invivo expression of angiopoietin-2, a FoxO1 target gene, in the heart of theembryo and offspring from diabetic rats. Methods: Heart explants obtained fromembryos of control rats at day 12 of pregnancy were incubated with a mTORinhibitor (Torin, 1µM) during 3 hours and phosphorylation of ribosomal proteinS6 (Ser-235/236) and FoxO1 (Ser-473) was measured by Western Blot. The experimental model ofdiabetes was obtained by streptozotocin administration to adult rats (50mg/kg).Control and diabetic rats were euthanized at day 12 of pregnancy, embryonichearts were collected and stored for P-FoxO1 and total FoxO1 measurement byWestern blot and expression of angiopoietin-2by qPCR assays. In the adult male offspring from diabetic rats, heart wasobtained for measurements of the mRNA expression of angiopoietin-2 by qPCR assays. Results: The mTOR inhibitor Torindecreased P-rpS6 (mTORC1 downstream target) (74%, p<0.05) and P-FoxO1 inembryonic hearts from control rats (28%, p<0.05). In the embryonic hearts ofdiabetic rats, P-FoxO1/total FoxO1 ratio was reduced when compared to controls(55%, p<0.05).