Deciphering the roles of O‐GlcNAcylation during CD4+ T‐cells activation

Abstract

O-GlcNAcylation is a dynamic post-translational modification of serine/threonine with β-linked N-acetylglucosamine. This cyto-nuclear modification is found in all multi-cellular organisms. Previous observations during chemical activation of CD4+ T-cells showed decreasing O-GlcNAc levels on cytosolic proteins while increasing on nuclear proteins. In addition, transcription factor Elf-1 involved in T-cell activation requires O-GlcNAcylation for proper translocation into nucleus. These data indicate that O-GlcNAcylation is an integral part of signal transduction during T-cell activation. To investigate this, we examined O-GlcNAcylation changes resulting from PMA/ionomycin activation of CD4+ T-cells. O-GlcNAc levels increased for nuclear and cytosolic proteins through the first 2 hrs then decreased through 5hrs. Further more, individual bands showed unique O-GlcNAcylation level changes. The cellular localization and amount of O-GlcNAc transferase (OGT) and O-GlcNAcase (OGase) were unchanged. In vitro measured enzymatic activity of O-GlcNAcase also did not change. These data suggest that O-GlcNAc level changes during T-cell activation are due to alteration in OGT or OGase specific interactions. (Supported by NIH grants CA42486 and HD13563. Dr. Hart receives a share of royalty received by the university on sales of the CTD 110.6 antibody. Terms of this arrangement are managed by JHU.)