RT Journal Article
SR Electronic
T1 TRPM4 is required for calcium oscillations downstream from the stretch-activated TRPV4 channel
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.12.15.472700
DO 10.1101/2021.12.15.472700
A1 Oleg Yarishkin
A1 Tam T. T. Phuong
A1 Felix Vazquez-Chona
A1 Jacques Bertrand
A1 Sarah N. Redmon
A1 Monika Lakk
A1 Christopher N. Rudzitis
A1 Jackson M. Baumann
A1 Eun Mi Hwang
A1 Darryl Overby
A1 David Križaj
YR 2021
UL http://biorxiv.org/content/early/2021/12/16/2021.12.15.472700.abstract
AB Transduction of mechanical information is influenced by physical, chemical and thermal cues but the molecular mechanisms through which transducer activation shapes temporal signaling remain underexplored. In the present study, electrophysiology, histochemistry and functional imaging were combined with gene silencing and heterologous expression to gain insight into calcium signaling downstream from TRPV4 (Transient Receptor Potential Vanilloid 4), a stretch-activated nonselective cation channel. We show that trabecular meshwork (TM) cells, which employ mechanotransduction to actively regulate intraocular pressure, respond to the TRPV4 agonist GSK1016790A with fluctuations in intracellular Ca2+ concentration ([Ca2+]i) and an increase in [Na+]i. ([Ca2+]i oscillations coincided with a monovalent cation current that was suppressed by BAPTA, Ruthenium Red and 9-phenanthrol, an inhibitor of TRPM4 (Transient Receptor Potential Melastatin 4) channels. Accordingly, TM cells expressed TRPM4 mRNA, protein at the expected 130-150 kDa and showed punctate TRPM4 immunoreactivity at the membrane surface. Genetic silencing of TRPM4 antagonized TRPV4-evoked oscillatory signaling whereas TRPV4 and TRPM4 co-expression in HEK-293 cells reconstituted the oscillations. Membrane potential recordings indicated that TRPM4-dependent oscillations required release of Ca2+ from internal stores. 9-phenanthrol did not affect the outflow facility in mouse eyes. Collectively, our results show that TRPV4 activity initiates dynamic calcium signaling in TM cells by stimulating TRPM4 channels and intracellular Ca2+ release. These findings provide insight into the complexity of membrane-cytosolic interactions during TRPV4 signaling and may foster strategies to promote homeostatic regulation and counter pathological remodeling within the conventional outflow pathway of the mammalian eye.Competing Interest StatementThe authors have declared no competing interest.