FUNCTIONAL MODULATION OF HUMAN PLURIPOTENT STEM CELLS BY O-LINKED N-ACETYLGUCOSAMINE

Abstract

THE O-LINKED-N-ACETYLGLUCOSAMINE (O-GLCNAC) POST TRANSLATIONAL MODIFICATION EMERGED AS AN IMPORTANT CUE IN CONTROLLING KEY CELL MECHANISMS. THIS THESIS AIMED TO INVESTIGATE THE ROLE AND SIGNIFICANCE OF O-GLCNAC IN HUMAN PLURIPOTENT STEM CELLS (HPSC). WE FIRST STARTED BY DEMONSTRATING O-GLCNAC REGULATES HPSC DIFFERENTIATION. WE THEN IDENTIFIED 235 HESC O-GLCNACYLATED PROTEINS BY MS INCLUDING RING2, A POLYCOMB PROTEIN CATALYSING THE UBIQUITINYLATION OF HISTONE H2A TO REPRESS GENE EXPRESSION. WE PROVED THAT RING2 WAS BEARING O-GLCNAC IN HESC AND MAPPED THE O-GLCNACYLATED SITES ON RING2 AT T250/S251. WE THEN DEMONSTRATED THAT O-GLCNACYLATION WAS MODULATING RING2 PROTEIN-PROTEIN INTERACTION TOWARDS CBX7 AND RYBP. INDEED, O-GLCNAC EXCESS INCREASED CBX7-RING2 AFFINITY AND DECREASED RYBP-RING2 AFFINITY. TO THE BEST OF OUR KNOWLEDGE, THIS IS THE FIRST REPORT DEMONSTRATING O-GLCNAC INVOLVEMENT IN HESC DIFFERENTIATION AND SHOWING THAT O-GLCNAC MODIFIES RING2 AND REGULATES RING2 PROTEIN-PROTEIN IN