PD17-02 UNIVERSAL LOSS OF COMPLEX I IN ONCOCYTOMA IS ASSOCIATED WITH DEFECTIVE MITOPHAGY VIA ALTERED GLUTATHIONE METABOLISM

Abstract

You have accessJournal of UrologyCME1 Apr 2023PD17-02 UNIVERSAL LOSS OF COMPLEX I IN ONCOCYTOMA IS ASSOCIATED WITH DEFECTIVE MITOPHAGY VIA ALTERED GLUTATHIONE METABOLISM Lin Lin, Neal Patel, Blake Wilde, Lucia Fernandez-del-Rio, Eirini Christodoulou, Shinji Ohtake, Randy Caliliw, Orian Shirihai, Xiaowu Gai, Heather Christofk, David Shackelford, and Brian Shuch Lin LinLin Lin More articles by this author , Neal PatelNeal Patel More articles by this author , Blake WildeBlake Wilde More articles by this author , Lucia Fernandez-del-RioLucia Fernandez-del-Rio More articles by this author , Eirini ChristodoulouEirini Christodoulou More articles by this author , Shinji OhtakeShinji Ohtake More articles by this author , Randy CaliliwRandy Caliliw More articles by this author , Orian ShirihaiOrian Shirihai More articles by this author , Xiaowu GaiXiaowu Gai More articles by this author , Heather ChristofkHeather Christofk More articles by this author , David ShackelfordDavid Shackelford More articles by this author , and Brian ShuchBrian Shuch More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003272.02AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Renal oncocytoma (RO) is the most commonly resected benign renal neoplasm. ROs are characterized by a dense accumulation of dysfunctional mitochondria possibly resulting by increased mitochondrial biogenesis and defective mitophagy. Although it is well known that ROs harbor recurrent inactivating mutations in mitochondrial genes encoding Complex I (NADH dehydrogenase) in the electron transport chain, the mechanism of defective mitophagy remains unclear. Here, we hypothesize that mitophagy inhibition in RO is regulated by Complex I loss, leading to increased glutathione that oxidizes key players in the mitophagy pathway. METHODS: RO and normal kidney (NK) tissues were obtained from patients undergoing surgical resection. DNA was isolated from frozen RO samples (n=18) and matched whole blood. Long-range PCR was performed to sequence mitochondrial DNA (mtDNA). Protein expression was analyzed using Western Blot. Complex I-IV activity, as measured by oxygen consumption rate, was analyzed by the Seahorse XF96 analyzer. Gene expression changes were evaluated using the Nanostring nCounter human metabolic pathway panel and analyzed by Rosalind. Metabolic profiles were measured using liquid chromatography-tandem mass spectrometry (LC-MS). Statistical calculations were performed using Graphpad Prism. RESULTS: A total of 13 ROs (72.2%) had mtDNA Complex I loss-of-function (LoF) mutations with 8 (44.4%) having high allele frequency (>50%). Compared to NK, nearly all ROs had reduced Complex I activity with a compensatory increase of Complex IV activity, irrespective of identified mtDNA mutation. On the protein level, there was a universal loss of Complex I with resultant compensatory increase of other complexes regardless of mtDNA status. Gene expression profiling revealed increased activation of AMPK pathway in ROs as well as altered glutathione metabolism, including increased biosynthesis and decreased breakdown. Metabolic profiling confirmed that both reduced and oxidized forms of glutathione were significantly enriched in ROs compared to NKs. The mechanism of glutathione inhibition of mitophagy is currently being investigated with possible candidates having dysregulated oxidation. CONCLUSIONS: The universal loss of Complex I activity in ROs is independent of mtDNA mutations. Complex I loss in RO is associated with increased glutathione, which in turn may result in impaired mitophagy. We continue to develop models to interrogate key drivers in this process. Source of Funding: AUA Urology Care Foundation Residency Research Award AUA Research Scholar Award © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e495 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Lin Lin More articles by this author Neal Patel More articles by this author Blake Wilde More articles by this author Lucia Fernandez-del-Rio More articles by this author Eirini Christodoulou More articles by this author Shinji Ohtake More articles by this author Randy Caliliw More articles by this author Orian Shirihai More articles by this author Xiaowu Gai More articles by this author Heather Christofk More articles by this author David Shackelford More articles by this author Brian Shuch More articles by this author Expand All Advertisement PDF downloadLoading ...