Interplay of myosin phosphatase and protein phosphatase-2A in the regulation of endothelial nitric-oxide synthase phosphorylation and nitric oxide production

• Published in: Scientific reports 2017-03, Vol.7 (1), p.44698-44698, Article 44698
• Main Authors: Bátori, Róbert, Bécsi, Bálint, Nagy, Dénes, Kónya, Zoltán, Hegedűs, Csaba, Bordán, Zsuzsanna, Verin, Alexander, Lontay, Beáta, Erdődi, Ferenc
• Format: Article
• Language: English
• Subjects: 13; 13/109; 13/89; 631/80/86/2341; 692/4017; 9/10; 96; 96/1; 96/34; 96/63; Animals; Catechin - analogs & derivatives; Catechin - pharmacology; Cattle; Cell Line; Dephosphorylation; Electric Impedance; Endothelial cells; Enzyme Activation - drug effects; Epigallocatechin gallate; Gene Silencing - drug effects; Human Umbilical Vein Endothelial Cells - drug effects; Human Umbilical Vein Endothelial Cells - metabolism; Humanities and Social Sciences; Humans; Kinases; Laminin; Light chains; Models, Biological; multidisciplinary; Myosin; Myosin-Light-Chain Phosphatase - metabolism; Nitric oxide; Nitric Oxide - biosynthesis; Nitric Oxide Synthase Type III - metabolism; Nitric-oxide synthase; Oxazoles - pharmacology; Phosphatase; Phosphoprotein phosphatase; Phosphorylation; Phosphorylation - drug effects; Phosphothreonine - metabolism; Protein kinase A; Protein kinase C; Protein Kinase C - metabolism; Protein phosphatase; Protein Phosphatase 2 - metabolism; Proteins; Pulmonary Artery - cytology; Rabbits; RhoA protein; RNA, Small Interfering - metabolism; Science; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep44698

The inhibitory phosphorylation of endothelial nitric oxide (NO) synthase (eNOS) at Thr497 (eNOS pThr497 ) by protein kinase C or RhoA-activated kinase is a major regulatory determinant of eNOS activity. The signalling mechanisms involved in the dephosphorylation of eNOS pThr497 have 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 eNOS pThr497 phosphatase. 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 eNOS pThr497 substrate (iii) phosphorylation of MYPT1 at Thr696 (MYPT1 pThr696 ) controls the activity of MP on eNOS pThr497 . 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 MYPT1 pThr696 and thereby stimulates MP activity inducing dephosphorylation of eNOS pThr497 and 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.