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Abstract: SA-PO738

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

Session Information

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
  • Liang, Lorrin, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
  • Sharma, Vineeta, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
  • Wilson, Gabrielle L., Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
  • Buerger, Florian, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
  • Bogdanovic, Radovan, The Institute of Mother and Child Health Care of Serbia "Dr Vukan Cupic", Belgrade, Serbia
  • Froehner, Stanley C., University of Washington Department of Physiology and Biophysics, Seattle, Washington, United States
  • Adams, Marvin, University of Washington Department of Physiology and Biophysics, Seattle, Washington, United States
  • Shril, Shirlee, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
  • Mane, Shrikant M., Department of Genetics, Yale University School of Medicine, New Haven, Connecticut, United States
  • Hildebrandt, Friedhelm, Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
  • Majmundar, Amar J., Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States
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