Relevance of Akt sumoylation in mouse embryonic stem cells

SREBROW, ANABELLA; PETRONE, MARÍA VICTORIA; VÁZQUEZ ECHEGARAY, CAMILA; GUBERMAN, ALEJANDRA; WAISMAN, ARIEL; TORO, AYELÉN; FRANCIA, MARCOS; BARAÑAO, LINO; SOLARI, CLAUDIA; COSENTINO, MARÍA SOLEDAD; SREBROW, ANABELLA; PETRONE, MARÍA VICTORIA; VÁZQUEZ ECHEGARAY, CAMILA; GUBERMAN, ALEJANDRA; WAISMAN, ARIEL; TORO, AYELÉN; FRANCIA, MARCOS; BARAÑAO, LINO; SOLARI, CLAUDIA; COSENTINO, MARÍA SOLEDAD

Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017

Embryonic stem cells (ESC) have the ability to self-renew indefinitely and to give rise to cells of all three germ layers. The PI3K/Akt pathway is involved in survival and proliferation and is key for maintaining the levels and activity of ESC?s essential transcription factors (TF) Oct4, Sox2 and Nanog. Recently, it has been reported that SUMO conjugation to Akt1 regulates the activity of thiskinase, with consequences in the splicing pattern, proliferation and cell cycle in different cultured cell lines. However, the relevance of this post-translational modification (PTM) of Akt1 hasn?t been studied in ESC.Our hypothesis is that SUMOylation of Akt1 is relevant for survival, proliferation and maintenance of ESC fundamental properties. This work was aimed to study the effect of this PMT of Akt1 on the regulation of Nanog expression, and to set up the conditions to induce apoptosis and detect this process in mouse ESC. First, ESC were transfected with expression vectors for Akt1 variantswith different capacity of being SUMOylated along with a Luciferase reporter vector driven by Nanog promoter. We found a differential activity of this promoter depending on Akt SUMOylation levels, suggesting that this Akt PTM could modulate Nanog expression in ESC (Analyzed using randomized block design ANOVA and Tukey test). To further determine the possible involvement of Akt1 SUMOylation in the regulation of ESC?s survival/apoptosis, we first set upthe conditions for inducing apoptosis in our cell culture system. CulturingESC in the absence of the cytokine LIF and the 2i inhibitor for up to 4 days induced apoptosis, as detected by DNA ladder assay, as well as by PARP-1 and Caspase 3 cleavage by Western Blot. Our preliminary results suggest that the SUMOylation of Akt1 could play a role on the expression of Nanog. We consider that studying the regulation of the fundamental properties of ESC is essential for their future application in regenerative medicine.