Left ventricular hypertrophy (LVH) represents an adaptive response to volume stress or pressure overload but can progress to contractile dysfunction and heart failure. Previously, we demonstrated that global or endothelial-specific deletion of transient receptor potential vanilloid 4 (TRPV4) channels protects against adverse cardiac remodeling following myocardial infarction (MI) or pressure overload (TAC) by inhibiting fibroblast differentiation or enhancing coronary angiogenesis, respectively. However, the specific contribution of cardiomyocyte TRPV4 to pathological remodeling remains unknown. To address this, we generated cardiomyocyte-specific TRPV4 knockout (TRPV4MKO) mice and subjected them to isoproterenol (ISO; 40 mg/kg/day)-induced cardiac hypertrophy for 14 days. ISO treatment induced significant hypertrophy in TRPV4lox/lox control mice but not in TRPV4MKO mice. In contrast, ISO provoked comparable interstitial fibrosis in both genotypes. Echocardiographic assessment revealed that cardiac function, as indicated by ejection fraction and fractional shortening, declined in TRPV4lox/lox mice but was preserved in TRPV4MKO mice. Single-nucleus RNA sequencing analysis showed marked downregulation of protein kinase G1 (PKG1) expression in hearts from patients with hypertrophic cardiomyopathy compared with healthy controls. Mechanistically, TRPV4 inhibition increased PKG1 expression and attenuated ISO-induced hypertrophy in AC16 human cardiomyocytes. Conversely, pharmacological inhibition of PKG1 with KT5823 exacerbated hypertrophic responses to ISO. Taken together, these findings suggest that cardiomyocyte-specific deletion of TRPV4 mitigates adverse cardiac remodeling by modulating PKG1 signaling, identifying the TRPV4–PKG1 axis as a potential therapeutic target for heart failure. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Endothelial cell (EC) metabolism plays a central role in vascular homeostasis, angiogenesis, and the pathogenesis of diseases such as tumor growth and cardiovascular dysfunction. Transient receptor potential vanilloid type 4 (TRPV4) is a mechanosensitive ion channel known to regulate key EC functions, including proliferation, migration, and angiogenesis; however, its role in endothelial metabolism remains unclear. In the present study, we investigated whether TRPV4 channels modulate endothelial function by regulating mitochondrial dynamics and metabolic activity. Confocal imaging revealed that normal endothelial cells (NEC) displayed perinuclear, rounded mitochondria, whereas TRPV4 knockout endothelial cells (KOEC) exhibited elongated, cytoplasm-dispersed mitochondria. Transmission electron microscopy confirmed these structural changes, showing well-defined cristae in KOEC. Flow cytometry demonstrated increased mitochondrial content in KOEC, accompanied by elevated expression of the mitochondrial biogenesis regulator PGC-1α. At the molecular level, KOEC demonstrated a higher fusion-to-fission protein ratio (OPA1/MFF), indicating enhanced mitochondrial fusion. Seahorse metabolic flux analysis further revealed increased basal and maximal oxygen consumption rates (OCR), ATP-linked respiration, and spare respiratory capacity in KOEC, all of which were attenuated by the OPA1 inhibitor MYLS22. Substrate utilization assays further revealed that TRPV4KOECs exhibited increased consumption of TCA cycle intermediates, as well as NADH and FADH substrates, compared to NECs and this effect was normalized by MYLS22. Functionally, MYLS22 treatment normalized abnormal EC proliferation, migration, and angiogenesis observed in KOEC. In vivo, MYLS22 restored normal tumor vascularization and suppressed tumor growth in endothelial-specific TRPV4 knockout mice. These findings reveal that TRPV4 channels regulate endothelial metabolism and angiogenesis through OPA1-dependent mitochondrial dynamics. Targeting TRPV4 or its downstream metabolic pathways may represent a promising therapeutic strategy for vascular and metabolic diseases characterized by endothelial dysfunction. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Endothelial-to-mesenchymal transition (EndMT) is a crucial cellular differentiation process essential for embryonic development and implicated in cardiovascular pathologies such as atherosclerosis and cardiac fibrosis. While soluble factors like transforming growth factor-beta (TGF-β) are established inducers of EndMT, mechanical forces including substrate stiffness, stretch, and shear stress also play key regulatory roles. However, the underlying mechanotransduction mechanisms remain poorly defined. This study examined the role of the mechanosensitive calcium channel TRPV4 in EndMT. Among the two isoforms tested, TGF-β2 proved to be a more potent inducer of EndMT than TGF-β1, promoting the transition of human microvascular endothelial cells (HMEC-1) into a mesenchymal phenotype marked by elevated α-smooth muscle actin (α-SMA) expression and reduced CD31 and VE-cadherin levels. Inhibition of TRPV4 with the selective antagonist GSK2193874 significantly attenuated TGF-β2–induced EndMT. Moreover, TGF-β2 increased TRPV4 protein expression and enhanced TRPV4-mediated calcium influx in response to the agonist GSK1016790A, effects that were blocked by GSK2. Mechanistically, TGF-β2 stimulated Rho (RhoGTP) activation and upregulation of transcription factors Snail, Slug, Twist-1, SIP-1, and ZEB-1. TRPV4 inhibition specifically reduced TGF-β2–induced Rho activation and Snail expression, but not other transcription factors. Finally, pharmacological inhibition of Rho pathway by Rho kinase inhibitor, Y27632 significantly attenuated TGF-β2–induced EndMT. Taken together, these findings identify TRPV4 as a key mediator of TGF-β2–induced EndMT through the Rho/Snail signaling pathway. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Aims The transient receptor potential vanilloid 4 ion channel is widely expressed in the gastrointestinal tract and contributes to epithelial barrier regulation, mechanosensation and innate immune signaling. However, its role in shaping gut microbiota composition and intestinal metabolic homeostasis remains unclear. This study aimed to determine whether deletion of TRPV4 influences gut microbial composition and intestinal ammonia levels. Materials and methods Fecal microbiota from wild type and TRPV4 knockout mice were analyzed using taxonomic profiling and microbial diversity approaches. Alpha diversity and beta diversity metrics were used to evaluate microbial richness, evenness, phylogenetic diversity and community structure. Ammonia concentration and pH were measured in cecal and colonic contents. Key findings Phylogenetic diversity differed significantly between wild type and TRPV4 knockout mice whereas microbial richness and evenness were not altered. Beta diversity analysis revealed marked differences in microbial community composition between genotypes. The ratio of Bacillota to Bacteroidetes was reduced by approximately 50 % in TRPV4 knockout mice due to decreased Bacillota and increased Bacteroidetes abundance. In addition, TRPV4 knockout mice exhibited significantly elevated ammonia levels in both the colon and cecum compared with wild type mice. Significance Deletion of TRPV4 alters gut microbial community structure and intestinal nitrogen metabolism without affecting overall microbial richness or evenness. These findings identify TRPV4 as a novel regulator of gut microbiota composition and metabolic homeostasis and suggest that ion channel dependent signaling contributes to the regulation of gut microbial ecology and metabolite balance.

Cutaneous melanoma remains the most lethal skin cancer due to profound tumor heterogeneity and the frequent development of resistance to current therapies. Here, we identify the cysteinyl leukotriene receptor 1 (CysLT1R) as a previously unrecognized driver of melanoma progression. Analysis of bulk RNA-sequencing datasets from The Cancer Genome Atlas (TCGA) revealed significantly elevated CysLT1R transcript in metastatic tumors compared to primary tumors. Functional studies in murine and human melanoma cells demonstrated that leukotriene D4 (LTD4)-mediated activation of CysLT1R promotes melanoma cell proliferation and invasion through the parallel engagement of YAP and ERK signaling pathways. Notably, melanoma cells express LTC4 synthase and secrete cysteinyl leukotrienes, establishing a constitutive autocrine signaling loop that sustains CysLT1R activity independently of the host niche. Genetic ablation or pharmacological inhibition of CysLT1R with MK571 significantly attenuated tumor growth in vivo and was associated with inhibition of the YAP-LOXL-2 signaling axis. In addition, studies using Cysltr1-/- mice reveal that host-derived CysLT1R signaling within the tumor microenvironment also contributes to melanoma progression. Together, these findings uncover a previously unrecognized pro-tumorigenic CysLT1R-ERK/YAP,LOXL-2 signaling circuit that promotes cutaneous melanoma progression and highlight CysLT1R as a potential therapeutic target for melanoma.

Angiogenesis, a cornerstone of vascular development, tissue regeneration, and tumor progression, is critically orchestrated by the metabolic behavior of endothelial cells (EC). Recent discoveries have redefined EC not as metabolically uniform entities, but as spatially and functionally heterogeneous populations whose metabolic states govern their angiogenic potential. This review presents a comprehensive synthesis of metabolic zonation in EC, spanning arterial, venous, and capillary domains, and highlights cell-type-specific programs during sprouting angiogenesis-including tip, stalk, and phalanx cells. We explore how distinct metabolic pathways-glycolysis, oxidative phosphorylation, fatty acid oxidation, and glutaminolysis-are differentially used across tissue contexts such as the brain, skeletal muscle, kidney, and tumor microenvironments. We discuss technological breakthroughs in spatial metabolomics, temporal (circadian) regulation of endothelial metabolism, and emerging clinical strategies to target EC metabolic vulnerabilities in cancer and ischemic diseases. Furthermore, we advocate for spatiotemporal modeling of EC metabolism using computational and machine learning frameworks to predict angiogenic behavior and accelerate therapeutic discovery. This integrative perspective underscores the need for precision-targeted angiogenic interventions and establishes metabolic zonation as a foundational principle in vascular biology.

Left ventricular hypertrophy is an adaptive response to volume stress or pressure overload that can ultimately lead to contractile dysfunction and heart failure. Previously, we demonstrated that global or endothelial-specific deletion of transient receptor potential vanilloid 4 (TRPV4) channels protects the heart from adverse remodeling following myocardial infarction (MI) or pressure-overload (TAC), through inhibition of fibroblast differentiation or increased microvasculature, respectively. However, the specific role of the cardiomyocyte TRPV4 in cardiac remodeling remains unclear. To investigate this, we generated cardiomyocyte specific-TRPV4 knockout mice (TRPV4 MKO ) and subjected them to Isoproterenol (ISO; 30mg/kg/day) treatment for 14 days. Echocardiography analysis revealed that cardiac function is preserved in TRPV4 MKO mice compared to TRPV4 lox/lox mice. Further, cardiac hypertrophy and fibrosis were reduced in TRPV4 MKO mice compared to TRPV4 lox/lox mice, post-ISO treatment. Importantly, single-nucleus RNA sequencing analysis revealed significant downregulation of Protein kinase G1 (PKG1) in the hearts of hypertrophic cardiomyopathy patients compared to healthy controls. Consistent with this, TRPV4 inhibition increased PKG1 expression levels and prevented ISO-induced hypertrophy in AC16 human cardiomyocytes. Finally, pharmacological inhibition of PKG1 using KT5823 exacerbated hypertrophy in AC16 cells in response to ISO. Taken together, our results suggest that cardiomyocyte-specific deletion of TRPV4 mitigates adverse cardiac remodeling via downregulating PKG1 and identifying the TRPV4/PKG1 signaling as a potential therapeutic target for heart failure.

Emerging evidence highlights the pivotal role of gut microbiota in regulating cardiovascular health and disease. The gut microbiota, a diverse community of microorganisms residing in the gastrointestinal tract, interacts with its host through metabolites, immune modulation, and systemic signaling pathways, collectively shaping cardiovascular physiology. Dysbiosis, or an imbalance in gut microbial composition, has been linked to various cardiovascular diseases (CVDs), including hypertension, heart failure and atherosclerosis. Key microbial metabolites such as short-chain fatty acids (SCFAs), trimethylamine N-oxide (TMAO) and lipopolysaccharides (LPS) have been implicated in mechanisms involving endothelial, cardiac fibroblast, cardiomyocyte dysfunction, systemic inflammation, and metabolic dysregulation. This review explores the dynamic interplay between the gut and the heart, focusing on: gut microbiota composition and its alterations in CVD; microbial-derived metabolites and their mechanistic roles in cardiovascular pathophysiology; pathways linking gut dysbiosis to endothelial, cardiac fibroblast and cardiomyocyte dysfunction, inflammation, and immune responses; and therapeutic opportunities targeting the gut-heart axis, including dietary interventions, prebiotics, probiotics and emerging microbiota-based strategies. By unraveling these intricate relationships, we aim to provide a comprehensive understanding of how gut microbiota shape CVD pathophysiology and discuss potential avenues for novel therapeutics in precision medicine.

Bladder cancer (BLCA) is the second most common urologic cancer in the US and worldwide which mostly affects the aging population. Despite several ongoing clinical trials, treatment paradigms for BLCA have not changed significantly. Here, we investigated the expression of transient receptor potential vanilloid type 4 (TRPV4) in BLCA patients and its role in calcium influx, cell proliferation, and migration using normal human urothelial cells and BLCA cells. Bioinformatic analysis of the UALCAN and cBioPortal databases revealed that TRPV4 expression is significantly higher in human BLCA tissues compared to adjacent normal tissues. Further, the TRPV4 expression was markedly elevated in early-stage BLCA and upregulated in muscle-invasive bladder cancer (MIBC) tissues. TRPV4 is expressed in both normal urothelial (SV-HUC-1) and BLCA (T-24) cells and functional assays demonstrated enhanced TRPV4-mediated calcium influx in T-24 compared to SV-HUC-1 cells. T-24 cells exhibited higher spreading on extracellular matrix (ECM) gels with increasing stiffness (0.2, 8, and 50 kPa) and exhibited migratory phenotype compared to SV-HUC-1 cells. Pharmacological inhibition of TRPV4 significantly reduced proliferation and migration in T-24 cells but had minimal effects on normal cells. Finally, treatment with cisplatin significantly reduced TRPV4 protein levels and TRPV4-mediated calcium influx in chemosensitive UM-UC-3 cells, which remained unchanged in chemoresistant T-24 cells, suggesting a potential role of TRPV4 in chemoresistance. In conclusion, TRPV4 may contribute to bladder cancer progression by regulating cell proliferation and migration and may impart resistance to chemotherapy. Targeting TRPV4 could present a novel therapeutic approach for managing bladder cancer progression and overcoming chemoresistance. Significance Statement:This study identifies TRPV4 as a critical driver of BLCA progression. Elevated TRPV4 gene expression in both early-stage and muscle-invasive bladder cancer (MIBC) tissues is associated with increased calcium signaling, cell proliferation, and migration. Importantly, TRPV4 inhibition selectively reduces BLCA growth and motility. Furthermore, TRPV4 is downregulated by cisplatin in chemo-sensitive but not chemo-resistant BLCA cells, underscoring its key role in bladder cancer chemoresistance. These findings position TRPV4 as a therapeutic target for enhancing BLCA treatment and overcoming drug resistance.

Opioid receptors are G protein-coupled receptors expressed by various cells in the heart, including myocytes and nerve fibres, and play a crucial role in modulating cardiac function. These receptors influence neural transmission, heart rate and myocyte contractility, offering cardioprotection. Our review provides a comprehensive examination of opioid receptor functions across multiple cardiovascular cell types, including cardiomyocytes, endothelial cells and smooth muscle cells, encompassing excitation-contraction coupling and vascular tone regulation. Additionally, we address the crosstalk between opioid receptors and other systems, such as the β-adrenoceptor system and the renin-angiotensin system. This integrated approach enables a more complete understanding of how opioid systems influence overall cardiovascular homeostasis, presenting significant advances in the field. Understanding the role of these receptors could help in developing novel treatments for various cardiovascular conditions. In conclusion, this review discusses the importance of opioid receptors and their signalling pathways in mediating cardiovascular functions, highlighting their potential as therapeutic targets for cardiovascular diseases.

Transient receptor potential vanilloid type 4 (TRPV4) is a mechanosensitive ion channel involved in the regulation of endothelial cell (EC) functions, including proliferation, migration, and angiogenesis. However, the molecular mechanisms underlying TRPV4-mediated regulation of EC activity remain inadequately understood. In this study, we explored whether TRPV4 channels influence endothelial function through modulation of mitochondrial dynamics. Confocal microscopy revealed a peri-nuclear localization of mitochondria in normal endothelial cells (NEC), whereas mitochondria in TRPV4 knockout endothelial cells (KOEC) were diffusely distributed throughout the cytoplasm. Transmission electron microscopy further confirmed the presence of rounded mitochondria in NEC, in contrast to elongated mitochondria with distinct cristae in KOEC. Notably, the distribution of mitochondria in KOEC increased in response to varying matrix stiffness, as observed when cells were cultured on extracellular matrix (ECM) gels with stiffness values mimicking pathological conditions (0.2, 8, and 50 kPa). At the molecular level, western blot analysis revealed an elevated ratio of fusion to fission proteins (Optic Atrophy 1 (OPA1)/mitochondrial fission factor (MFF)) in KOEC compared to NEC. Furthermore, seahorse flux analysis indicated significantly higher basal oxygen consumption rate (OCR), maximal OCR, ATP-linked OCR, and spare capacity in KOEC relative to NEC, all of which were notably reduced upon treatment with the small molecule OPA1 inhibitor MYLS22. Importantly, MYLS22 restored TRPV4 knockout-associated defects in proliferation, migration, and angiogenesis in ex vivo models. In vivo, MYLS22 treatment significantly impaired tumor angiogenesis and growth in endothelial-specific TRPV4 knockout mice. Collectively, these findings demonstrate that TRPV4 channels regulate angiogenesis by modulating mitochondrial dynamics through OPA1 and highlight endothelial TRPV4 as a novel therapeutic target for the regulation of mitochondrial function in endothelial cells. This work was supported by the National Institutes of Health (R01HL148585) and AHA-TPA-971237 to CKT, and AHA Pre-Doc to KD. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Autophagy is a physiological process responsible for degrading misfolded proteins and damaged organelles within cells. However, the role of endothelial autophagy in angiogenesis remains poorly understood. In this study, we demonstrate that knockdown of TRPV4 channels attenuated autophagy in human endothelial cells (EC) in a matrix stiffness-dependent manner as evidenced by reduced LC3B-II positive autophagosomes. Unbiased RNA sequencing further revealed decreased expression of autophagy genes in TRPV4 knocked down EC compared to WT EC. Mechanistically, TRPV4 knockdown led to increased nuclear translocation of YAP and reduced LC3B-II expression. Notably, the inhibition of YAP with verteporfin restored LC3B-II autophagosomes in TRPV4 knocked down EC. Interestingly, TRPV4 knockdown resulted in significant downregulation of phospho-AMPK and concomitant upregulation of phospho-mTOR. Treatment with rapamycin reversed AMPK/MTOR expression pattern and normalized abnormal angiogenesis exhibited by TRPV4 knocked down EC. Finally, in a pathological tumor angiogenesis model, verteporfin-mediated YAP inhibition significantly reduced tumor angiogenesis and tumor growth in TRPV4 -/- mice compared to TRPV4 +/+ mice. These findings suggest that TRPV4 regulates endothelial autophagy via YAP/AMPK/mTOR pathway during angiogenesis and identifies TRPV4 as a potential therapeutic target for tumor angiogenesis and growth. This work was supported by the National Institutes of Health and American Heart Association (R01HL148585 and AHA-TPA-971237) to CKT. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Bladder cancer (BLCA) is the second most common urologic cancer in the United States and worldwide and mostly affects the aging population. Despite several ongoing clinical trials, treatment paradigms for BLCA have not changed significantly. Here, we investigated the expression of transient receptor potential vanilloid type 4 (TRPV4) in patients with BLCA and its role in calcium influx, cell proliferation, and migration using normal human urothelial cells and BLCA cells. Bioinformatic analysis of the University of Alabama at Birmingham Cancer Data Analysis Portal and cBioPortal databases revealed that TRPV4 expression is significantly higher in human BLCA tissues than in normal adjacent tissues. Furthermore, TRPV4 expression was markedly elevated in early-stage BLCA and upregulated in muscle-invasive bladder cancer tissues. TRPV4 is expressed in both normal urothelial (SV-HUC-1) and BLCA (T-24) cells, and functional assays demonstrated enhanced TRPV4-mediated calcium influx in T-24 compared with SV-HUC-1 cells. T-24 cells exhibited higher spreading on extracellular matrix gels with increasing stiffness (0.2, 8, and 50 kPa) and exhibited a migratory phenotype compared to SV-HUC-1 cells. Pharmacological inhibition of TRPV4 significantly reduced proliferation and migration in T-24 cells but had minimal effects on normal cells. Finally, treatment with cisplatin significantly reduced TRPV4 protein levels and TRPV4-mediated calcium influx in chemosensitive UM-UC-3 cells but remained unchanged in chemoresistant T-24 cells, suggesting a potential role of TRPV4 in chemoresistance. In conclusion, TRPV4 may contribute to BLCA progression by regulating cell proliferation and migration and may impart resistance to chemotherapy. Targeting TRPV4 could present a novel therapeutic approach for managing BLCA progression and overcoming chemoresistance. SIGNIFICANCE STATEMENT: This study identified transient receptor potential vanilloid type 4 (TRPV4) as a critical driver of bladder cancer (BLCA) progression. TRPV4 gene expression is elevated in both early-stage and muscle-invasive BLCA tissues. Importantly, TRPV4 inhibition selectively reduces BLCA growth and motility. Furthermore, TRPV4 is downregulated by cisplatin in chemosensitive but not chemoresistant BLCA cells, underscoring its key role in bladder cancer chemoresistance. These findings position TRPV4 as a therapeutic target for enhancing BLCA treatment and overcoming drug resistance.

Uncontrolled angiogenesis underlies various pathological conditions such as cancer, age‐related macular degeneration (AMD), and proliferative diabetic retinopathy (PDR). Hence, targeting pathological angiogenesis has become a promising strategy for the treatment of cancer and neovascular ocular diseases. However, current pharmacological treatments that target VEGF signaling have met with limited success either due to acquiring resistance against anti‐VEGF therapies with serious side effects including nephrotoxicity and cardiovascular‐related adverse effects in cancer patients or retinal vasculitis and intraocular inflammation after intravitreal injection in patients with AMD or PDR. Therefore, there is an urgent need to develop novel strategies which can control multiple aspects of the pathological microenvironment and regulate the process of abnormal angiogenesis. To this end, vascular normalization has been proposed as an alternative for antiangiogenesis approach; however, these strategies still focus on targeting VEGF or FGF or PDGF which has shown adverse effects. In addition to these growth factors, calcium has been recently implicated as an important modulator of tumor angiogenesis. This article provides an overview on the role of major calcium channels in endothelium, TRP channels, with a special focus on TRPV4 and its downstream signaling pathways in the regulation of pathological angiogenesis and vascular normalization. We also highlight recent findings on the modulation of TRPV4 activity and endothelial phenotypic transformation by tumor microenvironment through Rho/YAP/VEGFR2 mechanotranscriptional pathways. Finally, we provide perspective on endothelial TRPV4 as a novel VEGF alternative therapeutic target for vascular normalization and improved therapy. © 2024 American Physiological Society. Compr Physiol 14:5389‐5406, 2024.

Transient receptor potential vanilloid type 4 (TRPV4) is a mechanically activated ion channel implicated in the regulation of endothelial cell (EC) proliferation, migration, and angiogenesis. However, the molecular mechanism(s) by which TRPV4 regulates EC functions remains underexplored. Here, we investigated if TRPV4 channels mediate endothelial function via modulation of mitochondria. Confocal microscopy showed a peri-nuclear localization of mitochondria in normal EC (NEC), while they were localized throughout the cell in TRPV4 knockout EC (KOEC). Furthermore, transmission electron microscopy confirmed clear round mitochondria in NEC compared to elongated mitochondria with distinct cristae in KOEC. Importantly, we found increased distribution of mitochondria in KOEC with increasing stiffness, when cultured on extracellular matrix (ECM) gels of varying stiffness that mimic the stiffness of matrix in pathophysiological conditions such as tumor or heart failure (0.2, 8, and 50 kPa). Mechanistically, western blot analysis showed increased fusion/fission protein ratio (Optic Atrophy 1 (OPA1)/mitochondrial fission factor (MFF)), in KOEC compared to NEC. Seahorse flux analyzer analysis demonstrated increased basal oxygen consumption rate (OCR), maximal OCR, ATP-linked OCR, and spare capacity in KOEC compared to NEC, which were significantly attenuated by a small molecule inhibitor of OPA1, MYLS22. Finally, MYLS22 normalized TRPV4-knockout mediated abnormal proliferation, migration, and angiogenesis ex vivo. Taken together, these findings indicate that mechanosensitive TRPV4 channels regulate mitochondrial phenotype and function during angiogenesis through OPA1. This work was supported by the National Institutes of Health (and R01HL148585 and AHA-TPA-971237) to CKT. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Left ventricular hypertrophy (LVH) is a bipolar response, starting as an adaptive response to the hemodynamic challenge, but over time progressing towards a maladaptive pathology with a loss of ventricular function. Despite the profound influence on cardiac function, the mechanotransduction mechanisms that regulate myocardial angiogenesis, leading to heart failure, are not well known. Here, we demonstrate that endothelial-specific deletion of mechanosensitive ion channel TRPV4 preserved cardiac function and structure and reduced fibrosis via increased capillary density compared to WT mice, 28 days post-transverse aortic constriction (TAC). Interestingly, comprehensive RNA sequencing analysis revealed an upregulation of pro-angiogenic factors (FGF2, NOS3, and VEGFα) in TRPV4 ECKO hearts after TAC compared to TRPV4 lox/lox . Further, an increased expression of VEGFR2 and activation of the YAP pathway was observed in TRPV4 ECKO hearts. Mechanistically, we found that downregulation of TRPV4 in human ECs induced matrix stiffness-dependent activation of YAP and VEGFR2 via the Rho/Rho kinase/LATS pathway. Our results thus suggest that endothelial TRPV4 acts as a mechanical break for coronary angiogenesis, and uncoupling TRPV4 mechanotransduction attenuates pathological cardiac hypertrophy by enhancing coronary angiogenesis.

Transient receptor potential vanilloid type 4 (TRPV4) is a mechanosensor that regulates endothelial cell (EC) proliferation, migration, and angiogenesis. However, the molecular mechanisms by which TRPV4 regulates EC functions are not well understood. In this study, we investigated if TRPV4 regulates EC function via modulation of mitochondria by employing three types of EC expressing different levels of TRPV4, normal (NEC), TRPV4-deficienct (TEC), and TRPV4 knockout (KOEC). First, we confirmed the functional expression of TRPV4 in these EC using qPCR and calcium imaging. Confocal images upon MitoTracker staining revealed spherical and/or round shaped mitochondria with a perinuclear localization in NEC while in TEC and KOEC the mitochondrial network was elongated and rod shaped with a whole cell distribution. Furthermore, Transmission Electron Microscopy confirmed the presence of clear round mitochondria in NEC compared to elongated mitochondria with distinct cristae in TEC and KOEC. These results indicate increased fusion in TRPV4 deficiency or deletion. When cultured on ECM gels of varying stiffness that mimic stiffness of matrix in pathophysiological conditions such as tumor or heart failure (0.2, 8, and 50 kPa), we found increased distribution of mitochondria in EC with increasing stiffness. Moreover, western blot analysis showed increased expression of a fusion/fission protein ratio (Optic Atrophy 1 (OPA1)/mitochondrial fission factor (MFF)), in TEC and KOEC. Further, uncoupling mitochondrial function by mitochondrial stressors (Oligomycin, FCCP, and Rot/AA) significantly increased basal oxygen consumption rate (OCR), maximal OCR, ATP-linked OCR, and spare capacity in TEC and KOEC than NEC. Finally, a small molecule inhibitor of OPA1, MYLS22, attenuated/normalized the mitochondrial energy metabolism to that of NEC but did not affect NEC. These findings suggest that mechanosensitive TRPV4 channels regulate EC mitochondrial morphology and function through increased OPA1. National Institutes of Health (R15CA202847, R01HL119705, and R01HL148585) to CKT This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.