Mechanosensitive interactions between Jag1 and Myo1c control Jag1 trafficking in endothelial cells

Morphogenesis of the cardiovascular system is responsive to hemodynamic cues. In endothelial cells the organization of morphogenic signaling proteins can be regulated by membrane presentation and internalization of proteins. How these signaling proteins are regulated by hemodynamics is unclear. One of the signaling proteins that is regulated by hemodynamics is Jagged1, a ligand in the Notch pathway. Here we set out to identify factors that differentially interact with Jagged1 in response to shear stress exposure, by combining an orbital shaker as a shear stress platform with endothelial cells expressing Jagged1 coupled to an APEX2-tag for proximity labeling. Myo1c was identified and confirmed through coimmunoprecipitation as a Jag1 interacting factor under static conditions, with reduced interaction after exposure to shear in endothelial cells. We showed that Jagged1 polarized downstream of shear followed by nucleograde transport of Jagged1. Myo1c knockout inhibited shear-induced Jagged1 polarization and consequent nucleograde transport. Further, Myo1c knockdown reduced membrane levels of Jagged1 under static conditions, but not under shear conditions. Together, our data reveal a role for Myo1c in the hemodynamic control of Jagged1 localization in endothelial cells.