PD63-07 OSTEOPONTIN (OPN) IS A NOVEL REGULATOR OF FIBROTIC TUBULAR DYSFUNCTION VIA Rac-1 AND p53 SIGNALING

You have accessJournal of UrologyInfections/Inflammation/Cystic Disease of the Genitourinary Tract: Kidney & Bladder II (PD63)1 May 2024PD63-07 OSTEOPONTIN (OPN) IS A NOVEL REGULATOR OF FIBROTIC TUBULAR DYSFUNCTION VIA Rac-1 AND p53 SIGNALING Asef Aziz, Sonia Mozumdar, Paul Higgins, and Rohan Samarakoon Asef AzizAsef Aziz , Sonia MozumdarSonia Mozumdar , Paul HigginsPaul Higgins , and Rohan SamarakoonRohan Samarakoon View All Author Informationhttps://doi.org/10.1097/01.JU.0001009384.23104.ca.07AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Chronic kidney disease (CKD) affects nearly 37 million individuals in the USA alone, with an estimated Medicare cost of over $100 billion for treatment. Severe kidney injury leads to tubular dysfunction via epithelial dedifferentiation, cell cycle arrest and deposition of fibrotic factors and matrix molecules leading to fibrosis. Lack of effective therapy to slow fibrosis sequela continue to impose heavy medical burden globally. Although OPN (a pro-inflammatory mediator) knockout mice are resistant to renal injury progression to fibrosis, precise mechanisms by which OPN exerts pathogenic effects are unclear. We hypothesized that renal epithelial upregulation of OPN leads to fibrotic tubular dysfunction. METHODS: OPN expression was induced in human HK-2 renal epithelial cells via lentiviral transfection of CMV driven OPN (CMV-OPN) or empty vector (CMV-Control) expression constructs. Cellular lysates of the transgenic cells were probed by western blot analysis to confirm OPN upregulation and to assess expression levels of various pro-fibrotic proteins. To effectively suppress Rac1 and p53 expression, OPN overexpressing cells were then stimulated with Rac1 shRNA, p53 shRNA or control shRNA lentiviral expression constructs. RESULTS: Renal tubular OPN overexpression promotes collagen-1 and fibronectin induction compared to CMV-Controls. Epithelial marker, E-Cadherin expression is significantly downregulated in CMV-OPN cells suggestive of role of OPN in tubular cell dedifferentiation and fibrosis. We also observed expression Rac-1b (a constitutively active isoform of Rac-GTPase) as well as p53 (a major growth arrest gene that initiates renal injury transition to CKD) are robustly induced in CMV-OPN cultures. Gene silencing of Rac-1 expression in the OPN transduced cells led to a decrease in fibrosis along with a decrease in OPN-induced p53 expression. Similarly, p53 knock down in CMV-OPN cells decreased the expression of fibronectin and collagen-1. CONCLUSIONS: OPN expression induces fibrotic tubular dysfunction in renal epithelial cells via Rac1b and p53 signaling. Future studies with kidney specific gene ablation of OPN in mice will test the feasibility of OPN targeting as a novel anti-fibrotic therapy. Source of Funding: N/A © 2024 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 211Issue 5SMay 2024Page: e1294 Advertisement Copyright & Permissions© 2024 by American Urological Association Education and Research, Inc.Metrics Author Information Asef Aziz More articles by this author Sonia Mozumdar More articles by this author Paul Higgins More articles by this author Rohan Samarakoon More articles by this author Expand All Advertisement PDF downloadLoading ...