title: beta-Actin regulates platelet nitric oxide synthase 3 activity through interaction with heat shock protein 90.
abstract: Cytoskeletal proteins are crucial in maintaining cellular structure and, in certain cell types, also play an essential role in motility and shape change. Nitric oxide (NO) is an important paracrine mediator of vascular and platelet function and is produced in the vasculature by the enzyme NO synthase type 3 (NOS-3). Here, we demonstrate in human platelets that the polymerization state of beta-actin crucially regulates the activation state of NOS-3, and hence NO formation, through altering its binding of heat shock protein 90 (Hsp90). We found that NOS-3 binds to the globular, but not the filamentous, form of beta-actin, and the affinity of NOS-3 for globular beta-actin is, in turn, increased by Hsp90. Formation of this ternary complex among NOS-3, globular beta-actin, and Hsp90, in turn, results in an increase in both NOS activity and cyclic guanosine-3',5'-monophosphate, an index of bioactive NO, as well as an increased rate of Hsp90 degradation, thus limiting the duration for which NOS-3 remains activated. These observations suggest that beta-actin plays a critical role in regulating NO formation and signaling in platelets.
authors.affiliation: Department of Clinical Pharmacology, Cardiovascular Division, School of Medicine, Center for Ultrastructural Imaging, King's College London, London SE1 9NH, United Kingdom.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ji
authors.forename: Géraldine
authors.initials: G
authors.lastname: Ferracci
authors.forename: Alice
authors.initials: A
authors.lastname: Warley
authors.forename: Malcolm
authors.initials: M
authors.lastname: Ward
authors.forename: Kit-Yi
authors.initials: KY
authors.lastname: Leung
authors.forename: Salma
authors.initials: S
authors.lastname: Samsuddin
authors.forename: Christian
authors.initials: C
authors.lastname: Lévêque
authors.forename: Lindsay
authors.initials: L
authors.lastname: Queen
authors.forename: Vikash
authors.initials: V
authors.lastname: Reebye
authors.forename: Pallavi
authors.initials: P
authors.lastname: Pal
authors.forename: Eugenia
authors.initials: E
authors.lastname: Gkaliagkousi
authors.forename: Michael
authors.initials: M
authors.lastname: Seager
authors.forename: Albert
authors.initials: A
authors.lastname: Ferro
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D001792:Blood Platelets / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D000199:Actins; D018841:HSP90 Heat-Shock Proteins; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III