title: Requirement of Ca(2+) and PKCdelta for Janus kinase 2 activation by angiotensin II: involvement of PYK2.
abstract: In vascular smooth muscle cells, angiotensin II (AngII) stimulates association of its G protein-coupled AngII type 1 (AT(1)) receptor with Janus kinase 2 (JAK2), resulting in the activation of signal transducer and activator of transcription proteins. Although the association and activation of subsequent signal transducer and activator of transcription proteins appear to prerequire JAK2 activation, the signaling mechanism by which the AT(1) receptor activates JAK2 remains uncertain. Here, we have examined the signaling mechanism required for JAK2 activation by AngII in vascular smooth muscle cells. We found that AngII, through the AT(1) receptor, rapidly stimulated JAK2 phosphorylation at Tyr(1007/1008), the critical sites for the kinase activation. By using selective agonists and inhibitors, we demonstrated that PLC and its derived signaling molecules, phosphatidylinositol triphosphate/Ca(2+) and diacylglycerol/PKC, were essential for AngII-induced JAK2 phosphorylation. The PKC isoform required for JAK2 activation appears to be PKCdelta since a selective PKCdelta but not PKCalpha/beta inhibitor and dominant-negative PKCdelta overexpression inhibited JAK2 activation. We further examined a link between JAK2 and a Ca(2+)/PKC-sensitive tyrosine kinase, PYK2. We found that PYK2 activation by AngII requires PKCdelta, and that PYK2 associates with JAK2 constitutively. Moreover, transfection of two distinct PYK2 dominant-negative mutants markedly inhibited AngII-induced JAK2 activation. From these data we conclude that AT(1)-derived signaling molecules, specifically Ca(2+) and PKCdelta, participate in AngII-induced JAK2 activation through PYK2. These data provide a new mechanistic insight by which the hormone AngII exerts its cytokine-like actions in mediating vascular remodeling.
authors.affiliation: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
authors.forename: Gerald D
authors.initials: GD
authors.lastname: Frank
authors.forename: Shuichi
authors.initials: S
authors.lastname: Saito
authors.forename: Evangeline D
authors.initials: ED
authors.lastname: Motley
authors.forename: Terukatsu
authors.initials: T
authors.lastname: Sasaki
authors.forename: Motoi
authors.initials: M
authors.lastname: Ohba
authors.forename: Toshio
authors.initials: T
authors.lastname: Kuroki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Inagami
authors.forename: Satoru
authors.initials: S
authors.lastname: Eguchi
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D051418:Focal Adhesion Kinase 2; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053614:Janus Kinase 2; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D010742:Phospholipid Ethers / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051745:Protein Kinase C-delta; D021381:Protein Transport / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D010742:Phospholipid Ethers; D011518:Proto-Oncogene Proteins; D044140:Receptor, Angiotensin, Type 1; D011945:Receptors, Angiotensin; D000804:Angiotensin II; C026659:edelfosine; D019000:Phosphotyrosine; C497260:Prkcd protein, rat; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; C496054:Ptk2b protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D010738:Type C Phospholipases; D002118:Calcium