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MP94-18: Urothelial cells express a functional succinate receptor GPR91

Tuesday, May 16
7:00 AM - 9:00 AM
Location: BCEC: Room 253AB

Presentation Authors: Abubakr Mossa, Monica Velasquez-Flores, Philippe Cammisotto, Lysanne Campeau*, Montreal, Canada

Introduction: Overactive bladder is associated with the metabolic syndrome. Increased succinate production is detected in the presence of hyperglycemia and hypoxemia, as with diabetes mellitus and metabolic syndrome. Succinate was recently identified as a major metabolic switch controlling metabolic functions in the body through its receptor GPR91 (SUCNR1). The aim of our study is to determine how succinate interacts with urothelial cells through its receptor.

Methods: Urothelial cells were isolated from female Sprague-Dawley rat bladder using a collagenase IV method. After confluency, cells were exposed to succinate then treated for microscopy and immunoblotting. Cyclic AMP and PGE2 were measured using an Elisa kit from Cayman Chemical Company. Nitric oxide was assessed by an colorimetric method. Retroviruses were generated for shRNA-mediated knockdown of GPR91.

Results: Urothelial cells were characterized using Cytokeratin 17 and the AE1/AE3 antibody. RT-PCR confirmed expression of GPR91. Short-term incubation of cells with succinate (200 µM) results in phosphorylation of Erk and c-Jun amino-terminal kinases (JNKs). Inhibition of the MAPK pathway by PD98059 (10 µM) inhibited increases of Erk-P elicited by succinic acid. On the other hand, pre-incubation of cells with succinate dose-dependently decreased the concentrations of intracellular cyclic AMP stimulated by forskolin. Succinate triggers entry of calcium inside urothelial cells as visualized by confocal microscopy. Long-term incubation of cells with succinate increased secretion of nitric oxide and decreased PGE2 release.Cells infected with shRNA retrovirus targeting GPR91 displayed a strong decrease in GPR91 expression. This was associated with a loss of succinate-stimulated Erk phosphorylation. Moreover, inhibition of cyclic AMP synthesis, increases in intracellular calcium and release of nitric oxide were all dramatically prevented.

Conclusions: GPR91 is expressed in urothelial cells. Binding of succinate to its receptor triggers phosphorylation of Erk and JNK, a process that requires the MAPK pathway. Inhibition of cyclic AMP production suggests the receptor is bound to protein Gi. Release of nitric oxide and decrease of PGE2 are under succinic acid control suggesting a potential cross-talk between urothelium and detrusor muscle.

Source Of Funding: FRQS

Lysanne Campeau, MD

McGill University

Dr. Lysanne Campeau completed her medical studies in 2005 and her urology residency in 2010 at McGill University. She then went on to pursue her clinical and research interest in voiding dysfunction at the Wake Forest Institute for Regenerative Medicine in North Carolina, where she obtained a PhD in the Department of Physiology and Pharmacology in 2013. She completed her clinical training at New York University in an accredited fellowship in Female Pelvic Medicine and Reconstructive Surgery. Her areas of specialization include neurogenic voiding disorders and incontinence, as well as pelvic reconstruction.

Dr. Campeau was recruited back as an Assistant Professor of Surgery at McGill University in 2013, where she joined the Jewish General Hospital Department of Urology for her research interest and expertise. She has been awarded the Royal College of Physicians and Surgeons of Canada Detweiler Travelling Fellowship, the American Urological Association Foundation Research Scholar Fellowship, the Quebec Urological Association Training Scholarship, the Canadian Urological Association Scholarship Foundation Salary Award and the Quebec Diabetes Start-up Research Fund. Most recently, she was awarded the Fonds de recherche Santé Québec Clinical Research Scholar Junior 1 Award which facilitates her research activities at the Lady Davis Institute. Dr. Campeau is actively involved in several research societies including the International Continence Society and the International Consultation on Incontinence Research Society.

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