Functional study of O-GlcNAc modification on extracellular signal-regulated kinase 2

Abstract

O-GlcNAcylation is a post-translational modification on nuclear and cytoplasmic proteins, attached to and removed from serine or threonine residues by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). O-GlcNAcylation is known to affect various cellular mechanisms, one of which is cell proliferation. The mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway is involved in cell proliferation, and activation of this pathway if known to increase OGT expression and O-GlcNAcylation.

This study aims to identify presence of O-GlcNAcylation in the MAPK pathway, specifically on ERK2, and determine the function of ERK2 O-GlcNAcylation in the pathway. Here we discovered that OGA inhibition increased nuclear localization of ERK2, indicating a relevance between the MAPK pathway and O-GlcNAcylation. Through immunoprecipitation and lectin precipitation of ERK2, we identified O-GlcNAcylation on both endogenous and exogenous ERK2. Co-immunoprecipitation results of MEK1 and ERK2 showed that OGT induced O-GlcNAcylation change corresponded to an increase in ERK2-MEK1 interaction. Examination of subcellular fractionation results showed that upon OGT overexpression, ERK2 nuclear localization was decreased.

In conclusion, we have observed that ERK2 is O-GlcNAcylated, and that this modification increased the interaction between ERK2 and MEK1, leading to decreased nuclear localization of ERK2 in HEK293 cells.