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Interaction between MyRIP and the actin cytoskeleton regulates Weibel-Palade body trafficking and exocytosis
journal contributionposted on 2020-07-15, 11:15 authored by Ianina L Conte, Nicola Hellen, Ruben Bierings, Gregory I Mashanov, Jean-Baptiste Manneville, Nikolai I Kiskin, Matthew J Hannah, Justin E Molloy, Tom Carter
Weibel-Palade body (WPB)-actin interactions are essential for the trafficking and secretion of von Willebrand factor; however, the molecular basis for this interaction remains poorly defined. Myosin Va (MyoVa or MYO5A) is recruited to WPBs by a Rab27A-MyRIP complex and is thought to be the prime mediator of actin binding, but direct MyRIP-actin interactions can also occur. To evaluate the specific contribution of MyRIP-actin and MyRIP-MyoVa binding in WPB trafficking and Ca(2+)-driven exocytosis, we used EGFP-MyRIP point mutants with disrupted MyoVa and/or actin binding and high-speed live-cell fluorescence microscopy. We now show that the ability of MyRIP to restrict WPB movement depends upon its actin-binding rather than its MyoVa-binding properties. We also show that, although the role of MyRIP in Ca(2+)-driven exocytosis requires both MyoVa- and actin-binding potential, it is the latter that plays a dominant role. In view of these results and together with the analysis of actin disruption or stabilisation experiments, we propose that the role of MyRIP in regulating WPB trafficking and exocytosis is mediated largely through its interaction with actin rather than with MyoVa.
ActinExocytosisMyRIPMyosin VaWeibel–Palade bodyActin CytoskeletonActinsCalciumCell LineCell MovementGreen Fluorescent ProteinsHuman Umbilical Vein Endothelial CellsHumansMyosin Heavy ChainsMyosin Type VProtein BindingProtein TransportVesicular Transport ProteinsWeibel-Palade BodiesMolloy FC001119Schaefer FC00115306 Biological Sciences11 Medical and Health SciencesDevelopmental Biology