Abstract: TH-PO0114
Proteomic Analysis of FSGS Protein NOS1AP Identifies Mutation-Impaired PTPN14 Interaction That Modulates YAP1 Activity
Session Information
- Integrative Genomics and Multi-Omics in Noncystic Genetic Kidney Disease
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1202 Genetic Diseases of the Kidneys: Non-Cystic (Complex and Non-Cystic Monogenic)
Authors
- Lau, Andrea, Division of Nephrology, Boston Children's Hospital, Boston, Massachusetts, United States
- Sharma, Vineeta, Division of Nephrology, Boston Children's Hospital, Boston, Massachusetts, United States
- Majmundar, Amar J., Division of Nephrology, Boston Children's Hospital, Boston, Massachusetts, United States
Background
Focal segmental glomerulosclerosis (FSGS) is a leading cause of chronic kidney disease caused by dysfunction in the filtering cells, podocytes. Genetic variants in the phospho-tyrosine binding (PTB) domain encoded by the FSGS disease gene NOS1AP (nitric oxide synthase 1 adaptor protein) cause a podocytopathy through unclear molecular mechanisms.
Methods
Wildtype (WT) and mutant tagged NOS1AP constructs were transfected in immortalized human podocytes. Quantitative immunoprecipitation (IP) proteomics (LC/MS/MS) was performed. Interactors were stratified by expression in five published kidney single cell mRNA sequencing (scRNAseq) datasets. Candidate IP, immunofluorescence (IF), siRNA knockdown, and quantitative RT-PCR studies were performed.
Results
IP proteomics of WT NOS1AP, patient variant NOS1AP C143Y, and biological NOS1AP mutant lacking the PTB domain yielded 2351 proteins. 28 proteins were significantly enriched in the WT group relative to both mutant groups (fold change≥1.5, FDR<1%), indicating PTB mutations abrogated these interactions. Hypothesizing that top interactors are highly expressed in podocyte clusters from scRNAseq datasets, we found the interactor PTPN14 (protein tyrosine phosphatase non-receptor type 14) was most selectively expressed in podocyte clusters of 28 NOS1AP interactors and ranked 4/101 in human protein tyrosine phosphatases (median z-score %cell expression=2). We confirmed that NOS1AP PTB mutations impair its interaction with endogenous PTPN14 in immortalized human podocytes and showed that endogenous Ptpn14 protein co-localizes with podocyte marker Nephrin in rodent kidney glomerular podocytes by IF. Published studies indicate that PTPN14 negatively regulates the essential podocyte transcription factor YAP1 and that, in contrast to Yap1 knockout mice, Ptpn14 deficiency is protective from podocyte injury in mice. We observed that YAP1 co-precipitates with PTPN14 through their WW-PPXY domains and with NOS1AP in a PTB mutation-dependent manner. PTPN14 knockdown in immortalized podocytes promotes YAP1 target gene expression, while NOS1AP knockdown has the opposite effect.
Conclusion
A novel NOS1AP:PTPN14 interaction in podocytes is disrupted by FSGS-associated mutations and modulates YAP1 transcriptional activity, highlighting potential molecular points of intervention in FSGS.
Funding
- NIDDK Support