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Loss of β1‐integrin from urothelium results in overactive bladder and incontinence in mice: a mechanosensory rather than structural phenotype
Author(s) -
Kanasaki Keizo,
Yu Weiqun,
Bodungen Maximilian,
Larigakis John D.,
Kanasaki Megumi,
Pena Francisco Ayala,
Kalluri Raghu,
Hill Warren G.
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.12-223404
Subject(s) - urothelium , integrin , mechanotransduction , overactive bladder , cystometry , urinary bladder , purinergic receptor , endocrinology , chemistry , medicine , microbiology and biotechnology , biology , pathology , receptor , alternative medicine
Bladder urothelium senses and communicates information about bladder fullness. However, the mechanoreceptors that respond to tissue stretch are poorly defined. Integrins are mechanotransducers in other tissues. Therefore, we eliminated β1‐integrin selectively in urothelium of mice using Cre‐LoxP targeted gene deletion. β1‐Integrin localized to basal/ intermediate urothelial cells by confocal microscopy. β1‐Integrin conditional‐knockout (β1‐cKO) mice lacking urothelial β1‐integrin exhibited down‐regulation and mislocalization of α3‐ and α5‐integrins by immunohistochemistry but, surprisingly, had normal morphology, permeability, and transepithelial resistance when compared with Cre‐negative littermate controls. β1‐cKO mice were incontinent, as judged by random urine leakage on filter paper (4‐fold higher spotting, P <0.01; 2.5‐fold higher urine area percentage, P <0.05). Urodynamic function assessed by cystometry revealed bladder overfilling with 80% longer intercontractile intervals ( P <0.05) and detrusor hyperactivity (3‐fold more prevoid contractions, P <0.05), but smooth muscle contractility remained intact. ATP secretion into the lumen was elevated (49 vs. 22 nM, P <0.05), indicating abnormal filling‐induced purinergic signaling, and short‐circuit currents (measured in Ussing chambers) revealed 2‐fold higher stretch‐activated ion channel conductances in response to hydrostatic pressure of 1 cmH 2 O ( P <0.05). We conclude that loss of integrin signaling from urothelium results in incontinence and overactive bladder due to abnormal mechanotransduction; more broadly, our findings indicate that urothelium itself directly modulates voiding.—Kanasaki, K., Yu, W., von Bodungen, M., Larigakis, J. D., Kanasaki, M., Ayala de la Pena, F., Kalluri, R., Hill, W.G. Loss of β1‐integrin from urothelium results in overactive bladder and incontinence in mice: a mechanosensory rather than structural phenotype. FASEB J. 27, 1950–1961 (2013). www.fasebj.org