The role of O-GlcNAcylation in mRNA nuclear export studied by single-molecule super-resolution microscopy.

Abstract

Characterizing the relationship between the nuclear export of mRNA and the O-GlcNAcylation of nuclear pore proteins is a critical process for understanding the dynamic effects of post-translational modifications on membrane protein structures. Specifically, it was reported that the concentration of O-GlcNAcylated nucleoporins (Nups) in the nuclear pore complexes (NPCs) can be significantly altered by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) inhibitor drugs. Combining two single-molecule super-resolution microscopy methods, STORM and SPEED microscopy, we found that the amount of messenger ribonucleoprotein particles (mRNPs) that successfully export through the NPC is approximately doubled when increasing the O-GlcNAcylation in the NPC. Reversely, five-fold less mRNPs can exit the nucleus to reach the cytoplasm with the decreased O-GlcNAcylation of Nups. Moreover, a virtual 3D imaging by SPEED microscopy revealed that the spatial distributions of these altered O-GlcNAcylated Nups colocalized well with the locations of Nups that are rich in phenylalanine-glycine (FG) repeats, suggesting the passage of mRNPs through the selective permeability barrier in the NPC is regulated by the amount of O-GlcNAcylated FG-Nups.