TRPV4 maintains the contractile phenotype of VSMCs by regulating CPI-17

Early vascular lesions are closely associated with the phenotypic switching of vascular smooth muscle cells (VSMCs). Transient receptor potential vanilloid family member 4 (TRPV4) calcium channels are crucial for regulating vascular function. However, whether they contribute to the phenotypic switching of VSMCs remains unknown. Therefore, this study used a smooth muscle-specific TRPV4 knockout mouse model (TRPV4_SMC^-/-) to investigate the role of TRPV4 in phenotypic switching. Wire myography revealed significantly reduced phenylephrine/9,11-Methanoepoxy PGH2 vasoconstrictor response in the TRPV4_SMC^-/- group compared to the control group. Furthermore, the TRPV4_SMC^-/- mice had reduced contractile-related gene and protein expression in the aorta, suggesting the VSMCs lost their contractile phenotype. Carotid artery injury exacerbated pathological vascular remodelling in the smooth muscle and significantly increased neointima formation in the TRPV4_SMC^-/- mice compared to the controls. In vitro experiments showed that VSMCs lacking TRPV4 had enhanced proliferation and migration. RNA sequencing demonstrated that the protein phosphatase 1 regulatory subunit 14a (CPI-17) is a pivotal regulator of VSMCs contraction and functionally associated with TRPV4-mediated vascular responses. Additionally, VSMCs exhibited similar phenotypes after silencing CPI-17 or TRPV4, indicating that they jointly regulate vasoconstriction. VSMCs overexpressing TRPV4 or CPI-17 had enhanced cell contraction, supporting our conclusion. Therefore, TRPV4 is a central coordinator of VSMC phenotypic homeostasis, and it maintains vascular homeostasis through molecular interactions with CPI-17 under physiological and injurious conditions. These results provide mechanistic insights into the vascular remodelling process and highlight potential therapeutic targets for vascular diseases characterised by phenotypic switching.