RRC ID 47634
Author Sano T, Kobayashi T, Negoro H, Sengiku A, Hiratsuka T, Kamioka Y, Liou LS, Ogawa O, Matsuda M.
Title Intravital imaging of mouse urothelium reveals activation of extracellular signal-regulated kinase by stretch-induced intravesical release of ATP.
Journal Physiol Rep
Abstract To better understand the roles played by signaling molecules in the bladder, we established a protocol of intravital imaging of the bladder of mice expressing a Förster/fluorescence resonance energy transfer (FRET) biosensor for extracellular signal-regulated kinase (ERK), which plays critical roles not only in cell growth but also stress responses. With an upright two-photon excitation microscope and a vacuum-stabilized imaging window, cellular ERK activity was visualized in the whole bladder wall, from adventitia to urothelium. We found that bladder distention caused by elevated intravesical pressure (IVP) activated ERK in the urothelium, but not in the detrusor smooth muscle. When bladder distension was prevented, high IVP failed to activate ERK, suggesting that mechanical stretch, but not the high IVP, caused ERK activation. To delineate its molecular mechanism, the stretch-induced ERK activation was reproduced in an hTERT-immortalized human urothelial cell line (TRT-HU1) in vitro. We found that uniaxial stretch raised the ATP concentration in the culture medium and that inhibition of ATP signaling by apyrase or suramin suppressed the stretch-induced ERK activation in TRT-HU1 cells. In agreement with this in vitro observation, pretreatment with apyrase or suramin suppressed the high IVP-induced urothelial ERK activation in vivo. Thus, we propose that mechanical stretch induces intravesical secretion of ATP and thereby activates ERK in the urothelium. Our method of intravital imaging of the bladder of FRET biosensor-expressing mice should open a pathway for the future association of physiological stimuli with the activities of intracellular signaling networks.
Volume 4(21)
Published 2016-11-1
DOI 10.14814/phy2.13033
PII 4/21/e13033
PMID 27905300
PMC PMC5112504
MeSH Adenosine Triphosphate / metabolism Animals Apyrase / metabolism Extracellular Signal-Regulated MAP Kinases / metabolism* Extracellular Signal-Regulated MAP Kinases / physiology Female Intravital Microscopy / methods* Mice Mice, Inbred C57BL Muscle, Smooth / metabolism Muscle, Smooth / physiology Signal Transduction / genetics* Urinary Bladder / diagnostic imaging* Urinary Bladder / physiology Urothelium / cytology Urothelium / diagnostic imaging* Urothelium / physiology Urothelium / ultrastructure
DNA material pCMV-VSV-G-RSV-Rev (RDB04393)