Kidney Week

Abstract: SA-PO738

Discovery of a Novel Podocyte Complex of Nephrotic Syndrome Disease Protein NOS1AP and Dystroglycan Complex (DGC) Component SNTA1

Session Information

• Glomerular Diseases: Podocyte Biology - II
  November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1304 Glomerular Diseases: Podocyte Biology

Authors

• Ball, David A., Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

David A. Ball,

• Liang, Lorrin, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

Lorrin Liang,

• Sharma, Vineeta, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

Vineeta Sharma,

• Wilson, Gabrielle L., Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

Gabrielle L. Wilson,

• Buerger, Florian, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

Florian Buerger,

• Bogdanovic, Radovan, The Institute of Mother and Child Health Care of Serbia "Dr Vukan Cupic", Belgrade, Serbia

Radovan Bogdanovic,

• Froehner, Stanley C., University of Washington Department of Physiology and Biophysics, Seattle, Washington, United States

Stanley C. Froehner,

• Adams, Marvin, University of Washington Department of Physiology and Biophysics, Seattle, Washington, United States

Marvin Adams,

• Shril, Shirlee, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

Shirlee Shril,

• Mane, Shrikant M., Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States

Shrikant M. Mane,

• Hildebrandt, Friedhelm, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

Friedhelm Hildebrandt,

• Majmundar, Amar J., Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States

Amar J. Majmundar,

Background

Nephrotic syndrome (NS) is a leading cause of pediatric chronic kidney disease. We discovered recessive mutations in NOS1AP, encoding nitric oxide synthase 1 adaptor protein, as a novel cause of NS (Majmundar Sci Adv 2021). We aimed to identify podocyte-specific NOS1AP interaction partners through which it regulates podocyte homeostasis.

Methods

Protein interactions were detected by co-immunoprecipitation (co-IP) assays using tagged cDNA constructs. Immunofluorescence (IF) staining and confocal microscopy were performed. Exome sequencing (ES) data from >800 NS families was analyzed.

Results

Of 85 putative NOS1AP-interacting proteins from published candidate interaction and proteomics studies, six were co-expressed (% cell expression z-score>1) with NOS1AP in podocyte clusters from at least three of four published kidney single cell mRNA sequencing (scRNAseq) datasets: FYN, PAK1, GSN, SPTAN1, SNTA1, HSPA12A. Upon co-overexpression in immortalized podocytes, NOS1AP exhibited bi-directional co-IP with only SNTA1 and HSPA12A and required its PDZ binding domain for the SNTA1 interaction. SNTA1 (syntrophin alpha 1) is an adaptor protein, which recruits other dystroglycan complex (DGC) proteins to the mouse neuromuscular junction (Adams J Neurosci 2010). DGC genes DAG1 and UTRN1 were co-expressed with NOS1AP and SNTA1 in podocyte clusters from published kidney scRNAseq datasets. By IF, we found that NOS1AP and SNTA1 co-localized with podocyte marker nephrin and was adjacent to alpha-dystroglycan in glomeruli from human and rat kidney sections. NOS1AP-induced filopodia formation, an NS intermediate phenotype, was reduced by SNTA1 knockdown in immortalized podocytes (32.8% versus 23.1%, X² = 4.4, p = 0.035). Finally, ES data was evaluated under the hypothesis that DGC genes are mutated in human NS. Candidate compound heterozygous variants in UTRN (p.S623F, p.T3177C), with rare prevalence in gnomAD and multiple severe in silico prediction scores, were detected in a 16-year-old female F1418 with nephrotic range proteinuria resistant to corticosteroids.

Conclusion

Our results suggest that NOS1AP and SNTA1 form a complex in glomerular podocytes, which may have implications for actin remodeling and human NS.

Funding

• NIDDK Support