O-GlcNAc modification of nuclear pore complexes accelerates bidirectional transport

Area of Science:

• Cell Biology
• Molecular Biology
• Biophysics

Background:

• Macromolecular transport across the nuclear envelope is crucial for cellular function and relies on nuclear pore complexes (NPCs).
• NPCs feature a permeability barrier formed by phenylalanine-glycine (FG) repeat domains, which selectively regulate transport.
• The role of O-linked N-acetylglucosamine (O-GlcNAc) modification, abundant in FG-repeat domains, in nucleocytoplasmic transport remains largely unknown.

Purpose of the Study:

• To investigate the functional significance of O-GlcNAc modification in nucleocytoplasmic transport kinetics.
• To elucidate the impact of O-GlcNAc on the permeability barrier of nuclear pore complexes.

Main Methods:

• Development of high-throughput optogenetic assays for quantifying nuclear import and export rates in living human cells.
• Utilizing superresolution imaging to visualize the localization of O-GlcNAc within NPCs.
• Assessing the effect of altered O-GlcNAc levels on both receptor-mediated and passive transport.

Main Results:

• Increased O-GlcNAc modification of NPCs accelerated the transport of proteins mediated by nuclear transport receptors (NTRs) in both import and export pathways.
• Decreased O-GlcNAc modification led to a slowdown in NTR-facilitated transport.
• Superresolution microscopy confirmed the enrichment of O-GlcNAc at the FG-repeat barrier.
• O-GlcNAc modification was also found to accelerate the passive diffusion of small, inert proteins through NPCs.

Conclusions:

• O-linked N-acetylglucosamine (O-GlcNAc) modification plays a significant role in accelerating nucleocytoplasmic transport.
• This acceleration is achieved by enhancing the overall, non-specific permeability of the FG-repeat barrier within NPCs.
• The mechanism may involve steric inhibition of interactions between FG repeats, thereby facilitating molecular passage.