title: Interaction between MyRIP and the actin cytoskeleton regulates Weibel-Palade body trafficking and exocytosis.
abstract: 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.
authors.affiliation: Cardiovascular and Cell Science Research Institute, St George's University, London SW17 0RE, UK.
authors.forename: Ianina L
authors.initials: IL
authors.lastname: Conte
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Hellen
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK.
authors.forename: Ruben
authors.initials: R
authors.lastname: Bierings
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK.
authors.forename: Gregory I
authors.initials: GI
authors.lastname: Mashanov
authors.affiliation: UMR144 CNRS/Institute Curie, Paris 75248, France.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Manneville
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK.
authors.forename: Nikolai I
authors.initials: NI
authors.lastname: Kiskin
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hannah
authors.affiliation: The Francis Crick Institute, Mill Hill Laboratory, London NW7 1AA, UK.
authors.forename: Justin E
authors.initials: JE
authors.lastname: Molloy
authors.affiliation: Cardiovascular and Cell Science Research Institute, St George's University, London SW17 0RE, UK tcarter@sgul.ac.uk.
authors.forename: Tom
authors.initials: T
authors.lastname: Carter
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D005089:Exocytosis / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D018995:Myosin Heavy Chains / Q000378:metabolism; D024701:Myosin Type V / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D020302:Weibel-Palade Bodies / Q000378:metabolism* / Q000502:physiology*
chemical_list: D000199:Actins; C501262:MYRIP protein, human; D033921:Vesicular Transport Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; C077511:MYO5A protein, human; D024701:Myosin Type V; D018995:Myosin Heavy Chains; D002118:Calcium
keywords: Actin; Exocytosis; MyRIP; Myosin Va; Weibel–Palade body