title: The Ca(2+) /calmodulin-dependent kinase kinase β-AMP-activated protein kinase-α1 pathway regulates phosphorylation of cytoskeletal targets in thrombin-stimulated human platelets.
abstract: BACKGROUND
  Platelet activation requires sweeping morphologic changes, supported by contraction and remodeling of the platelet actin cytoskeleton. In various other cell types, AMP-activated protein kinase (AMPK) controls the phosphorylation state of cytoskeletal targets.
  
  
  OBJECTIVE
  To determine whether AMPK is activated during platelet aggregation and contributes to the control of cytoskeletal targets.
  
  
  RESULTS
  We found that AMPK-α1 was mainly activated by thrombin, and not by other platelet agonists, in purified human platelets. Thrombin activated AMPK-α1 ex vivo via a Ca(2+) /calmodulin-dependent kinase kinase β (CaMKKβ)-dependent pathway. Pharmacologic inhibition of CaMKKβ blocked thrombin-induced platelet aggregation and counteracted thrombin-induced phosphorylation of several cytoskeletal proteins, namely, regulatory myosin light chains (MLCs), cofilin, and vasodilator-stimulated phosphoprotein (VASP), three key elements involved in actin cytoskeletal contraction and polymerization. Platelets isolated from mice lacking AMPK-α1 showed reduced aggregation in response to thrombin, and this was associated with defects in MLC, cofilin and VASP phosphorylation and actin polymerization. More importantly, we show, for the first time, that the AMPK pathway is activated in platelets of patients undergoing major cardiac surgery, in a heparin-sensitive manner.
  
  
  CONCLUSIONS
  AMPK-α1 is activated by thrombin in human platelets. It controls the phosphorylation of key cytoskeletal targets and actin cytoskeletal remodeling during platelet aggregation.
authors.affiliation: Institut de Recherche Expérimentale et Clinique (IREC), Pôle de Recherche Cardiovasculaire, Université catholique de Louvain, Brussels, Belgium.
authors.forename: M-B
authors.initials: MB
authors.lastname: Onselaer
authors.forename: C
authors.initials: C
authors.lastname: Oury
authors.forename: R W
authors.initials: RW
authors.lastname: Hunter
authors.forename: S
authors.initials: S
authors.lastname: Eeckhoudt
authors.forename: N
authors.initials: N
authors.lastname: Barile
authors.forename: C
authors.initials: C
authors.lastname: Lecut
authors.forename: N
authors.initials: N
authors.lastname: Morel
authors.forename: B
authors.initials: B
authors.lastname: Viollet
authors.forename: L-M
authors.initials: LM
authors.lastname: Jacquet
authors.forename: L
authors.initials: L
authors.lastname: Bertrand
authors.forename: K
authors.initials: K
authors.lastname: Sakamoto
authors.forename: J-L
authors.initials: JL
authors.lastname: Vanoverschelde
authors.forename: C
authors.initials: C
authors.lastname: Beauloye
authors.forename: S
authors.initials: S
authors.lastname: Horman
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008841:Actin Cytoskeleton / Q000187:drug effects* / Q000201:enzymology; D051339:Actin Depolymerizing Factors / Q000378:metabolism; D000818:Animals; D000925:Anticoagulants / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006348:Cardiac Surgical Procedures; D015815:Cell Adhesion Molecules / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006493:Heparin / Q000627:therapeutic use; D006801:Humans; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology*; D013997:Time Factors; D000098662:Vasodilator-Stimulated Phosphoprotein
chemical_list: D051339:Actin Depolymerizing Factors; D000925:Anticoagulants; D015815:Cell Adhesion Molecules; D008840:Microfilament Proteins; D018994:Myosin Light Chains; D010750:Phosphoproteins; D010975:Platelet Aggregation Inhibitors; D047428:Protein Kinase Inhibitors; D000098662:Vasodilator-Stimulated Phosphoprotein; D006493:Heparin; C548179:Prkaa1 protein, mouse; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D055372:AMP-Activated Protein Kinases; C526180:PRKAA1 protein, human; D013917:Thrombin
keywords: AMP-activated protein kinase; cytoskeleton; platelet aggregation; signal transduction; thrombin