Cross-talk Between SUMOylation and Phosphorylation in Germ Cells

Abstract

SUMOylation and phosphorylation are post-translational modifications that have been identified as important regulatory events that are implicated in several cellular processes. The aim of this research was to study the cross-talk between SUMOylation and phosphorylation during the cell cycle, specifically by assessing the activity of various kinases including CDC2, ERK1 and 2, PLK1, AURKB, and AKT, upon inhibition of SUMOylation. SUMOylation was inhibited utilizing RNAi technology, and we are currently generating a mouse model through which inhibition of SUMOylation in germ cells is achieved in vivo to be used for further research on this matter. Our data suggest that inhibition of SUMOylation decreased the inhibitory phosphorylation of CDC2, and increased the activating phosphorylation of ERK, AURKB, and AKT; therefore, their activity is normally inhibited by SUMOylation. In a different manner, inhibition of SUMOylation resulted in a slight decrease in the activating phosphorylation of PLK1, hinting that its activity is activated by SUMOylation—an observation which was then confirmed in an additional experiment utilizing OA and GA. Further studies should address the precise molecular mechanism of SUMO activation or inhibition of these and other kinases involved in regulation of the cell cycle.