A microtubule stability switch alters isolated vascular smooth muscle calcium flux in response to matrix rigidity.

During ageing, the extracellular matrix of the aortic wall becomes more rigid. In response, VSMCs generate enhanced contractile forces. Our previous findings demonstrate that VSMC volume is enhanced in response to increased matrix rigidity, but our understanding of mechanisms regulating this process remain incomplete. In this current study, we show that microtubule stability in VSMCs is reduced in response to enhanced matrix rigidity via piezo1-mediated Ca2+ influx. Moreover, VSMC volume and Ca2+ flux was regulated by microtubule dynamics; microtubule stabilising agents reduced both VSMC volume and Ca2+ flux on rigid hydrogels, whereas microtubule destabilising agents increased VSMC volume and Ca2+ flux on pliable hydrogels. Finally, we show that disruption of the microtubule deacetylase HDAC6 uncoupled these processes and increased K40 alpha tubulin acetylation, VSMC volume and Ca2+ flux on pliable hydrogels, but did not alter VSMC microtubule stability. These findings uncover a microtubule stability switch that controls VSMC volume by regulating Ca2+ flux. Together, these data demonstrate that manipulation of microtubule stability can modify VSMC response to matrix stiffness.