Tags

Type your tag names separated by a space and hit enter

A collagen-related peptide regulates phospholipase Cgamma2 via phosphatidylinositol 3-kinase in human platelets.
Biochem J. 1999 Aug 15; 342 (Pt 1):171-7.BJ

Abstract

The collagen receptor glycoprotein VI (GPVI) induces platelet activation through a similar pathway to that used by immune receptors. In the present study we have investigated the role of phosphatidylinositol 3-kinase (PI 3-kinase) in GPVI signalling. Our results show that collagen-related peptide {CRP: [GCP*(GPP*)(10)GCP*G](n); P*=hydroxyproline}, which is selective to GPVI, induces formation of phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] and phosphatidylinositol 3,4-bisphosphate [PI(3, 4)P(2)] in platelets. The increase in the two 3-phosphorylated lipids is inhibited completely by wortmannin and by LY294002, two structurally unrelated inhibitors of PI 3-kinase. The formation of inositol phosphates and phosphatidic acid (PA), two markers of phospholipase C (PLC) activation, by CRP are inhibited by between 50 and 85% in the presence of wortmannin and LY294002. This is associated with inhibition of elevation of intracellular Ca(2+) ([Ca(2+)](i)) and aggregation. Wortmannin and LY294002 also partially inhibit elevation of Ca(2+) by CRP in murine megakaryocytes. Microinjection of the pleckstrin-homology PH domain of Bruton's tyrosine kinase, which binds selectively to PI(3,4, 5)P(3), but not the R28C (Arg(28)-->Cys) mutant which binds to PI(3, 4,5)P(3) with low affinity, also inhibits elevation of [Ca(2+)](i) in megakaryocytes, suggesting that it is this lipid species which mediates the action of the PI 3-kinase pathway. Studies in platelets show that the action of wortmannin and LY294002 is not mediated through an alteration in tyrosine phosphorylation of PLCgamma2. These results demonstrate that PI 3-kinase is required for full activation of PLCgamma2 by GPVI in platelets and megakaryocytes.

Authors+Show Affiliations

Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, U.K.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

10432314

Citation

Pasquet, J M., et al. "A Collagen-related Peptide Regulates Phospholipase Cgamma2 Via Phosphatidylinositol 3-kinase in Human Platelets." The Biochemical Journal, vol. 342 (Pt 1), 1999, pp. 171-7.
Pasquet JM, Bobe R, Gross B, et al. A collagen-related peptide regulates phospholipase Cgamma2 via phosphatidylinositol 3-kinase in human platelets. Biochem J. 1999;342 (Pt 1):171-7.
Pasquet, J. M., Bobe, R., Gross, B., Gratacap, M. P., Tomlinson, M. G., Payrastre, B., & Watson, S. P. (1999). A collagen-related peptide regulates phospholipase Cgamma2 via phosphatidylinositol 3-kinase in human platelets. The Biochemical Journal, 342 (Pt 1), 171-7.
Pasquet JM, et al. A Collagen-related Peptide Regulates Phospholipase Cgamma2 Via Phosphatidylinositol 3-kinase in Human Platelets. Biochem J. 1999 Aug 15;342 (Pt 1):171-7. PubMed PMID: 10432314.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A collagen-related peptide regulates phospholipase Cgamma2 via phosphatidylinositol 3-kinase in human platelets. AU - Pasquet,J M, AU - Bobe,R, AU - Gross,B, AU - Gratacap,M P, AU - Tomlinson,M G, AU - Payrastre,B, AU - Watson,S P, PY - 1999/8/5/pubmed PY - 1999/8/5/medline PY - 1999/8/5/entrez SP - 171 EP - 7 JF - The Biochemical journal JO - Biochem J VL - 342 (Pt 1) N2 - The collagen receptor glycoprotein VI (GPVI) induces platelet activation through a similar pathway to that used by immune receptors. In the present study we have investigated the role of phosphatidylinositol 3-kinase (PI 3-kinase) in GPVI signalling. Our results show that collagen-related peptide {CRP: [GCP*(GPP*)(10)GCP*G](n); P*=hydroxyproline}, which is selective to GPVI, induces formation of phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] and phosphatidylinositol 3,4-bisphosphate [PI(3, 4)P(2)] in platelets. The increase in the two 3-phosphorylated lipids is inhibited completely by wortmannin and by LY294002, two structurally unrelated inhibitors of PI 3-kinase. The formation of inositol phosphates and phosphatidic acid (PA), two markers of phospholipase C (PLC) activation, by CRP are inhibited by between 50 and 85% in the presence of wortmannin and LY294002. This is associated with inhibition of elevation of intracellular Ca(2+) ([Ca(2+)](i)) and aggregation. Wortmannin and LY294002 also partially inhibit elevation of Ca(2+) by CRP in murine megakaryocytes. Microinjection of the pleckstrin-homology PH domain of Bruton's tyrosine kinase, which binds selectively to PI(3,4, 5)P(3), but not the R28C (Arg(28)-->Cys) mutant which binds to PI(3, 4,5)P(3) with low affinity, also inhibits elevation of [Ca(2+)](i) in megakaryocytes, suggesting that it is this lipid species which mediates the action of the PI 3-kinase pathway. Studies in platelets show that the action of wortmannin and LY294002 is not mediated through an alteration in tyrosine phosphorylation of PLCgamma2. These results demonstrate that PI 3-kinase is required for full activation of PLCgamma2 by GPVI in platelets and megakaryocytes. SN - 0264-6021 UR - https://www.unboundmedicine.com/medline/citation/10432314/A_collagen_related_peptide_regulates_phospholipase_Cgamma2_via_phosphatidylinositol_3_kinase_in_human_platelets_ L2 - https://www.ncbi.nlm.nih.gov/pmc/articles/pmid/10432314/ DB - PRIME DP - Unbound Medicine ER -