Modification of CHFR by O-linked N-acetylglucosamine regulates its stability

Abstract

O-linked β-N-acetylglucosamine (O-GlcNAc) modification (O-GlcNAcylation) of proteins is important for modulating many cellular processes such as signal transduction, transcription, translation and proteasomal degradation. Only two enzymes are known to regulate O-GlcNAcylation in mammals: O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). CHFR tumor suppressor is a checkpoint protein that delays cell cycle progression upon DNA damage. Moreover, CHFR ubiquitinates key mitotic kinases such as Aurora A and PLK1 leading to their degradation by proteasomes. Althrough the significance role in the control of cell growth, little is known on how CHFR activity is regulated. Here, i showed that tumor suppressor CHFR was modified with O-GlcNAc. Moreover, the levels of O-GlcNAcylated CHFR increased when overexpressed OGT and/or OGA was blocked by Thiamet G, an O-GlcNAcase inhibitor. And CHFR was modified with O-GlcNAc at Ser164 and Ser165, analysed by mass spectrometry. I confirmed that O-GlcNAcylation of CHFR positively regulates its stability. Thus, O-GlcNAcylation may contribute a new regulatory mechanism of CHFR.