title: Interplay of myosin phosphatase and protein phosphatase-2A in the regulation of endothelial nitric-oxide synthase phosphorylation and nitric oxide production.
abstract: The inhibitory phosphorylation of endothelial nitric oxide (NO) synthase (eNOS) at Thr497 (eNOSpThr497) by protein kinase C or RhoA-activated kinase is a major regulatory determinant of eNOS activity. The signalling mechanisms involved in the dephosphorylation of eNOSpThr497have not yet been clarified. This study identifies myosin phosphatase (MP) holoenzyme consisting of protein phosphatase-1 catalytic subunit (PP1c) and MP target subunit-1 (MYPT1) as an eNOSpThr497phosphatase. In support of this finding are: (i) eNOS and MYPT1 interacts in various endothelial cells (ECs) and in in vitro binding assays (ii) MYPT1 targets and stimulates PP1c toward eNOSpThr497substrate (iii) phosphorylation of MYPT1 at Thr696 (MYPT1pThr696) controls the activity of MP on eNOSpThr497. Phosphatase inhibition suppresses both NO production and transendothelial resistance (TER) of ECs. In contrast, epigallocatechin-3-gallate (EGCG) signals ECs via the 67 kDa laminin-receptor (67LR) resulting in protein kinase A dependent activation of protein phosphatase-2A (PP2A). PP2A dephosphorylates MYPT1pThr696and thereby stimulates MP activity inducing dephosphorylation of eNOSpThr497and the 20 kDa myosin II light chains. Thus an interplay of MP and PP2A is involved in the physiological regulation of EC functions implying that an EGCG dependent activation of these phosphatases leads to enhanced NO production and EC barrier improvement.
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.
authors.forename: Róbert
authors.initials: R
authors.lastname: Bátori
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.|MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.
authors.forename: Bálint
authors.initials: B
authors.lastname: Bécsi
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.
authors.forename: Dénes
authors.initials: D
authors.lastname: Nagy
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Kónya
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Hegedűs
authors.affiliation: Vascular Biology Center, Division of Pulmonary Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Bordán
authors.affiliation: Vascular Biology Center, Division of Pulmonary Medicine, Medical College of Georgia, Augusta University, Augusta, GA, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Verin
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.
authors.forename: Beáta
authors.initials: B
authors.lastname: Lontay
authors.affiliation: Department of Medical Chemistry, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.|MTA-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, Debrecen, Egyetem tér 1, H-4032, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Erdődi
mesh_terms: D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D002417:Cattle; D002460:Cell Line; D017097:Electric Impedance; D004789:Enzyme Activation / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008387:Marine Toxins; D008954:Models, Biological; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010080:Oxazoles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010769:Phosphothreonine / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology; D034741:RNA, Small Interfering / Q000378:metabolism; D011817:Rabbits; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D008387:Marine Toxins; D010080:Oxazoles; D034741:RNA, Small Interfering; D010769:Phosphothreonine; D009569:Nitric Oxide; C059041:calyculin A; D002392:Catechin; C045651:epigallocatechin gallate; D052250:Nitric Oxide Synthase Type III; D011493:Protein Kinase C; D054648:Protein Phosphatase 2; D043263:Myosin-Light-Chain Phosphatase; C490372:PPP1R12A protein, human; D013755:Tetradecanoylphorbol Acetate