Signaling Pathways Mediating Bradykinin-Induced Contraction in Murine and Human Detrusor Muscle

Abstract

Bradykinin (BK) has been proposed to modulate urinary bladder functions and implicated in the pathophysiology of detrusor overactivity. The present study aims to elucidate the signaling pathways of BK-induced detrusor muscle contraction, with the goal of better understanding the molecular regulation of micturition and identifying potential novel therapeutic targets of its disorders. Experiments have been carried out on bladders isolated from wild-type or genetically modified [smooth muscle-specific knockout (KO): Gαq/11-KO, Gα12/13-KO and constitutive KO: thromboxane prostanoid (TP) receptor-KO, cyclooxygenase-1 (COX-1)-KO] mice and on human bladder samples. Contractions of detrusor strips were measured by myography. Bradykinin induced concentration-dependent contractions in both murine and human bladders, which were independent of secondary release of acetylcholine, ATP, or prostanoid mediators. B2 receptor antagonist HOE-140 markedly diminished contractile responses in both species, whereas B1 receptor antagonist R-715 did not alter BK's effect. Consistently with these findings, pharmacological stimulation of B2 but not B1 receptors resembled the effect of BK. Interestingly, both Gαq/11- and Gα12/13-KO murine bladders showed reduced response to BK, indicating that simultaneous activation of both pathways is required for the contraction. Furthermore, the Rho-kinase (ROCK) inhibitor Y-27632 markedly decreased contractions in both murine and human bladders. Our results indicate that BK evokes contractions in murine and human bladders, acting primarily on B2 receptors. Gαq/11-coupled and Gα12/13-RhoA-ROCK signaling appear to mediate these contractions simultaneously. Inhibition of ROCK enzyme reduces the contractions in both species, identifying this enzyme, together with B2 receptor, as potential targets for treating voiding disorders.

Gardnerella Exposures Alter Bladder Gene Expression and Augment Uropathogenic Escherichia coli Urinary Tract Infection in Mice

“…In addition to the connection to UTI, the genes and biological pathways affected by Gardnerella in our mouse model are related to bladder function and intersect with a wide range of other urological conditions, including but not limited to bladder cancer, urinary incontinence, bladder pain syndrome and interstitial cystitis. For example, cholinergic and bradykinin receptors and the neuropeptide neruotensin (Nts) mediate bladder muscle cell contraction ( Dong et al., 2015 ; Dalghi et al., 2020 ; Borsodi et al., 2021 ). Type 1 bradykinin receptors like Bdkrb1 are generally not expressed in healthy tissue but are induced by inflammatory mediators and injury ( Marceau et al., 1997 ), which is consistent with the increase in expression after Gardnerella exposure.…”

RhoA/ROCK1 regulates the mitochondrial dysfunction through Drp1 induced by Porphyromonas gingivalis in endothelial cells

“…CCG‐1423 (APExBIO) selectively inhibits SRF‐mediated transcription of Rho signalling pathway activation 21 . Y‐27632 (AbMole Bioscience) is a pharmacologically specific inhibitor of ROCK 22 . They were used to determine the regulatory role of RhoA/ROCK1 pathway in P. gingivalis infection cells.…”

“… 21 Y‐27632 (AbMole Bioscience) is a pharmacologically specific inhibitor of ROCK. 22 They were used to determine the regulatory role of RhoA/ROCK1 pathway in P. gingivalis infection cells. Control cells were those exposed to DMSO only.…”

Editorial: Kinin 2022 Meeting, Annecy, France

“…Kinga Borsodi from Semmelweis University in Budapest, Hungary, showed that bladder contraction was mediated primarily via B2R [9]. In both human and murine bladders, contractions were independent of acetylcholine, ATP, or prostanoid mediators.…”