title: Cross talk between serine/threonine and tyrosine kinases regulates ADP-induced thromboxane generation in platelets.
abstract: ADP-induced thromboxane generation depends on Src family kinases (SFKs) and is enhanced with pan-protein kinase C (PKC) inhibitors, but it is not clear how these two events are linked. The aim of the current study is to investigate the role of Y311 phosphorylated PKCδ in regulating ADP-induced platelet activation. In the current study, we employed various inhibitors and murine platelets from mice deficient in specific molecules to evaluate the role of PKCδ in ADP-induced platelet responses. We show that, upon stimulation of platelets with 2MeSADP, Y311 on PKCδ is phosphorylated in a P2Y1/Gq and Lyn-dependent manner. By using PKCδ and Lyn knockout murine platelets, we also show that tyrosine phosphorylated PKCδ plays a functional role in mediating 2MeSADP-induced thromboxane generation. 2MeSADP-induced PKCδ Y311 phosphorylation and thromboxane generation were potentiated in human platelets pre-treated with either a pan-PKC inhibitor, GF109203X or a PKC α/β inhibitor and in PKC α or β knockout murine platelets compared to controls. Furthermore, we show that PKC α/β inhibition potentiates the activity of SFK, which further hyper-phosphorylates PKCδ and potentiates thromboxane generation. These results show for the first time that tyrosine phosphorylated PKCδ regulates ADP-induced thromboxane generation independent of its catalytic activity and that classical PKC isoforms α/β regulate the tyrosine phosphorylation on PKCδ and subsequent thromboxane generation through tyrosine kinase, Lyn, in platelets.
authors.forename: Dheeraj
authors.initials: D
authors.lastname: Bhavanasi
authors.forename: Rachit
authors.initials: R
authors.lastname: Badolia
authors.forename: Bhanu Kanth
authors.initials: BK
authors.lastname: Manne
authors.forename: Sumalaxmi
authors.initials: S
authors.lastname: Janapati
authors.forename: Carol T
authors.initials: CT
authors.lastname: Dangelmaier
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mazharian
authors.forename: Jianguo
authors.initials: J
authors.lastname: Jin
authors.forename: Soochong
authors.initials: S
authors.lastname: Kim
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Chen
authors.forename: Yotis A
authors.initials: YA
authors.lastname: Senis
authors.affiliation: Satya P. Kunapuli PhD, Department of Physiology and Sol Sherry Thrombosis Center,, Temple University School of Medicine,, 3420 North Broad street, MRB 414, Philadelphia PA, 19140, USA, Tel.: +1 215 707 4615, Fax: +1 215 707 6944, E-mail: spk@temple.edu.
authors.forename: Satya P
authors.initials: SP
authors.lastname: Kunapuli
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D007527:Isoenzymes; D018345:Mice, Knockout; D010766:Phosphorylation; D015539:Platelet Activation / Q000187:drug effects*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000097:blood* / Q000172:deficiency / Q000235:genetics; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D058912:Purinergic P2Y Receptor Agonists / Q000494:pharmacology*; D058472:Receptors, Purinergic P2Y1 / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013928:Thromboxane A2 / Q000097:blood*; D019061:src-Family Kinases / Q000097:blood / Q000235:genetics
chemical_list: D007527:Isoenzymes; D047428:Protein Kinase Inhibitors; D058912:Purinergic P2Y Receptor Agonists; D058472:Receptors, Purinergic P2Y1; D013928:Thromboxane A2; D000244:Adenosine Diphosphate; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D011493:Protein Kinase C
keywords: ADP receptors; Platelet physiology; protein kinase C; protein tyrosine kinases; thromboxane A2