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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.
Dalal et al. (Wed,) studied this question.