NUP133 Controls Nuclear Pore Assembly, Transcriptome Composition, and Cytoskeleton Regulation in Podocytes

Area of Science:

• Nephrology
• Molecular Biology
• Genetics

Background:

• Steroid-resistant nephrotic syndrome (SRNS) often progresses to end-stage renal disease.
• Hereditary SRNS is frequently caused by mutations in podocyte genes, including nuclear pore complex components like NUP133.
• The specific mechanisms by which nucleoporin mutations cause podocyte dysfunction in SRNS are not fully understood.

Purpose of the Study:

• To investigate the pathomechanisms of NUP133-linked nucleoporopathies in human podocytes.
• To analyze the effects of NUP133 loss-of-function on podocyte transcriptome, nuclear pore assembly, and cytoskeleton.
• To compare the impact of different NUP133 mutations on podocyte function.

Main Methods:

• CRISPR/Cas9-mediated genome editing to create an in vitro model of NUP133-linked nucleoporopathies in human podocytes.
• Transcriptome analysis to identify alterations in gene expression.
• Assessment of nuclear pore assembly and cytoskeleton regulation.

Main Results:

• Loss of NUP133 function disrupted nuclear pore structure and altered the podocyte-specific transcriptome.
• Impaired cellular protrusion generation was observed in NUP133-deficient podocytes.
• Specific SRNS-related NUP133 mutations caused only mild defects, suggesting a partial loss-of-function due to impaired Y-complex interaction and reduced NUP133 levels.

Conclusions:

• NUP133 loss-of-function significantly impacts podocyte biology, contributing to SRNS pathogenesis.
• Reduced NUP133 protein levels and impaired Y-complex interactions are likely key mechanisms underlying NUP133-related SRNS.
• This study provides a valuable in vitro model for investigating nucleoporin-related kidney diseases.