Deletion of Endothelial TRPV4 Protects Heart From Pressure Overload–Induced Hypertrophy

Abstract

BACKGROUND: Left ventricular hypertrophy is a bipolar response, starting as an adaptive response to the hemodynamic challenge, but over time develops maladaptive pathology partly due to microvascular rarefaction and impaired coronary angiogenesis. Despite the profound influence on cardiac function, the mechanotransduction mechanisms that regulate coronary angiogenesis, leading to heart failure, are not well known. METHODS: We subjected endothelial-specific knockout mice of mechanically activated ion channel, TRPV4 (transient receptor potential cation channel subfamily V member 4; TRPV4 ECKO ) to pressure overload via transverse aortic constriction and examined cardiac function, cardiomyocyte hypertrophy, cardiac fibrosis, and apoptosis. Further, we measured microvascular density and underlying TRPV4 mechanotransduction mechanisms using human microvascular endothelial cells, extracellular matrix gels of varying stiffness, unbiased RNA sequencing, small interfering RNA, Western blot, quantitative-PCR, and confocal immunofluorescence techniques. RESULTS: We demonstrate that endothelial-specific deletion of TRPV4 preserved cardiac function, cardiomyocyte structure, and reduced cardiac fibrosis compared with TRPV4 lox/lox mice, 28 days post–transverse aortic constriction. Interestingly, comprehensive RNA sequencing analysis revealed an upregulation of proangiogenic factors (VEGFα [vascular endothelial growth factor α], NOS3 [nitric oxide synthase 3], and FGF2 [fibroblast growth factor 2]) with concomitant increase in microvascular density in TRPV4 ECKO hearts after transverse aortic constriction compared with TRPV4 lox/lox . Further, an increased expression of VEGFR2 (vascular endothelial growth factor receptor 2) and activation of the YAP (yes-associated protein) pathway were observed in TRPV4 ECKO hearts. Mechanistically, we found that downregulation of TRPV4 in endothelial cells induced matrix stiffness–dependent activation of YAP and VEGFR2 via the Rho/Rho kinase/large tumor suppressor kinase pathway. CONCLUSIONS: Our results suggest that endothelial TRPV4 acts as a mechanical break for coronary angiogenesis, and uncoupling endothelial TRPV4 mechanotransduction attenuates pathological cardiac hypertrophy by enhancing coronary angiogenesis.

TRPV4 Channels Promote Pathological, but Not Physiological, Cardiac Remodeling through the Activation of Calcineurin/NFAT and TRPC6

“…Previous studies suggest that TRPV4 could also have an effect on CM [24,25], and our results indicate that TRPV4 inhibition reduces CM hypertrophy, either by direct effect on these cells or by modulatory cross-talking between FB and CM. Additionally, recent research proposes that deleting TRPV4 in endothelial cells might preserve cardiac function by enhancing coronary angiogenesis [37]. We did not assess the mechanisms by which arrhythmia inducibility was reduced in TRPV4−/− mice compared to TRPV4+/+ mice, which could be explained by mere reduction in the arrhythmogenic substrate (i.e., fibrosis) or by specific antiarrhythmic mechanisms as opposed to CM, as suggested by recent reports [38].…”

Angiotensin II induces endothelial dysfunction and vascular remodeling by downregulating TRPV4 channels

“…HMEC-1 were cultured as described previously, on MatTek glass bottom dishes (MatTek, Ashland, MA, United States). After treatment with Ang II as described above, cells were loaded with Fluo-4/AM (4 μM) for 25 min and were washed in previously described Ca 2+ media [ 8 , 14 ]. Ca 2+ imaging was performed on an Olympus FluoView 300 microscope (Olympus, Shinjuku, Tokyo, Japan)/Leica SP5 confocal microscope after stimulation with the TRPV4 agonist, GSK1016790A (100 nM).…”

A Hierarchical Mechanotransduction System: From Macro to Micro

“…Different from physiological cardiac hypertrophy driven by hemodynamic overload, pathological hypertrophy caused by chronic hypertension is associated with maladaptive ECM remodeling, myofibroblast activation, cardiomyocyte death, and re‐activated fetal genes. [ 337 , 338 , 339 ] These pathological changes are caused by impaired Ca 2+ and reactive oxygen species (ROS) homeostasis, hyperactive signaling pathways (e.g., mTORC2/AKT, ERK, and YAP), and altered transcription circuits, [ 340 ] which may be predominantly mediated by mechanotransduction encompassing mechanosensitive channels, [ 339 , 341 ] caveolae, adhesions, and specialized structures in cardiomyocyte (e.g., sarcomere, desmosomes, and intercalated disc). [ 342 ] In this regard, targeting mechanotransduction could be a valuable strategy to treat patients affected by this devastating disease.…”