RanGAP1, the most Prominently SUMOylated Lens Proteins Regulates Cell Cycle in Lens

Abstract

Purpose : SUMOylation is an important post-translation modification to regulate protein functions. Our previous studies have shown that SUMOylation activates the p32 Pax6 to regulate downstream gene expression both in vitro and in vivo (Yan et al., 1990. PNAS). Moreover, our recent studies have shown that SUMOylation regulates SP-1 to account for differential regulation of lens differentiation (Gong et al. 2014. PNAS). Here we demonstrate that SUMOylation of the most prominent SUMO-conjugated lens protein regulates cell cycle of lens epithelial cells and plays an important role during lens development.

Methods : Confocal microscope was used to record the cell cycle progress. Immunocytochemistry was used to detect the expression and localization of RanGAP1 and related protein components. SiRNA-mediated knockdown of RanGAP1 and pRedGFP-RanGAP1-mediated over expression were used to change the expression levels of RanGAP1.

Results : RanGAP1 expression was knocked down in mouse lens epithelial cells (aTN4-1) and human lens epithelial cells (HLE) via siRNA or shRNA respectively, and consequently both two types of lens cells were shown significantly abnormality in their cell cycle progression. RanGap1 knockdown resulted in mitotic spindle defects, leading to chromosome misalignment with abnormal cytokinesis and multinuclear cells.

Conclusions : SUMOylation regulation of RanGAP1 plays an important role in helping to execute its normal functions in cell cycle control. (Supported by Research prevent blindness, NSFC and Zhongshan Ophthalmic Center)

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.