AKT SUMOYLATION IS REQUIRED FOR NANOG PROMOTER INDUCTION IN MOUSE EMBRYONIC STEM CELLS

COSENTINO, MARÍA SOLEDAD; TORO, AYELEN; BARAÑAO, LINO; FRANCIA, MARCOS; SOLARI, CLAUDIA; WAISMAN, ARIEL; VAZQUEZ ECHEGARAY, CAMILA; PETRONE, MARÍA VICTORIA; GUBERMAN, ALEJANDRA

Ciudad de Buenos Aires

Simposio; Frontiers in Bioscience 3; 2018

IBioBA-CONICET-MPSP

Embryonic stem cells (ESC) are derived from the inner cell mass of blastocysts. Under specific culture conditions, they can self-renew indefinitely, preserving their potential to be differentiated to cells of all three germ layers. This undifferentiated state is mainly maintained by the Leukemia Inhibitory Factor (LIF) added to the serum containing culture media. The PI3K/AKT signaling transduction pathway is switched on by LIF and is crucial for the expression and activity of the ESC?s essential transcription factors Oct4, Sox2 and Nanog. It has been reported that modification of Akt1 by SUMO conjugation regulates the activity of this kinase, with direct consequences in the splicing pattern, cell growth and survival in cultured cell lines. However, the role of this post-translational modification (PTM) of Akt1 has not been studied in ESC yet.Our hypothesis is that SUMOylation of Akt1 is relevant for the maintenance of ESC fundamental properties. This work was aimed to study the effect of this PMT of Akt1 on the activity of the Nanog promoter. We transfected W4 ESC line with expression vectors of Akt1 variants with different capacity of being SUMOylated along with a Luciferase reporter vector driven by the Nanog gene promoter.Our results suggest that Akt SUMOylation is required for enhancing the Nanog promoter activity. We observed an induction with those variants that can be SUMOylated and a complete loss of this effect with those in which SUMO conjugation is diminished. With the purpose of studying the molecular mechanism involved, we found that this effect can be observed using either LIF, LIF&2i or no LIF culture media on W4 wild type cell line. Moreover, we detected the same effect on a W4 p53-KO cell line. Linear Mixed Models was used for testing all comparisons, obtaining statistically significant differences (p