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Phosphatidylinositol (3,4,5)-trisphosphate stimulates phosphorylation of pleckstrin in human platelets.
J Biol Chem. 1995 Sep 29; 270(39):22807-10.JB

Abstract

We have reported that platelets exposed to thrombin or thrombin receptor-directed ligand activate phospholipase C and rapidly accumulate phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) and phosphatidylinositol (3,4)-bisphosphate (PtdIns(3,4)P2) as a function of the activation of phosphoinositide (PI) 3-kinases in a GTP-binding protein-dependent manner. In such platelets, serine- and threonine-directed phosphorylation of pleckstrin also occurs and has been attributed to protein kinase C activation. We now report that the phosphorylation of pleckstrin is partially dependent upon PI 3-kinase. Pleckstrin phosphorylation in response to thrombin receptor stimulation is progressively susceptible to inhibition by wortmannin, a potent and specific inhibitor of platelet PI 3-kinases. PI 3-kinase thus seems to play a gradually increasing role in promoting pleckstrin phosphorylation. The IC50 for wortmannin in inhibiting SFLLRN-stimulated 3-phosphorylated phosphoinositide accumulation is 10 nM, and that (i.e. 50% of maximum inhibition) for inhibiting pleckstrin phosphorylation is 15 nM. Synthetic PtdIns(3,4,5)P3, when added to saponin-permeabilized (but not intact) platelets, causes wortmannin-insensitive phosphorylation of pleckstrin. PtdIns(3,4,5)P3 also overcomes the inhibition by wortmannin of thrombin- or guanosine 5'-3-O-(thio)trisphosphate-stimulated pleckstrin phosphorylation. In contrast, PtdIns(4,5)P2 or inositol (1,3,4,5)-tetrakisphosphate are ineffective in these respects. The pattern of phosphorylation of pleckstrin activated by PtdIns(3,4,5)P3 is not distinguishable from that of pleckstrin phosphorylated in intact platelets exposed to protein kinase C-activating beta-phorbol myristate acetate, mimicking diacylglycerol. Activation of protein kinase(s) by PtdIns(3,4,5)P3 thus offers a route for pleckstrin phosphorylation in vivo that is an alternative to activation of phospholipase C-->diacylglycerol-->protein kinase C.

Authors+Show Affiliations

Jefferson Cancer Institute, Philadelphia, Pennsylvania, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

7559410

Citation

Zhang, J, et al. "Phosphatidylinositol (3,4,5)-trisphosphate Stimulates Phosphorylation of Pleckstrin in Human Platelets." The Journal of Biological Chemistry, vol. 270, no. 39, 1995, pp. 22807-10.
Zhang J, Falck JR, Reddy KK, et al. Phosphatidylinositol (3,4,5)-trisphosphate stimulates phosphorylation of pleckstrin in human platelets. J Biol Chem. 1995;270(39):22807-10.
Zhang, J., Falck, J. R., Reddy, K. K., Abrams, C. S., Zhao, W., & Rittenhouse, S. E. (1995). Phosphatidylinositol (3,4,5)-trisphosphate stimulates phosphorylation of pleckstrin in human platelets. The Journal of Biological Chemistry, 270(39), 22807-10.
Zhang J, et al. Phosphatidylinositol (3,4,5)-trisphosphate Stimulates Phosphorylation of Pleckstrin in Human Platelets. J Biol Chem. 1995 Sep 29;270(39):22807-10. PubMed PMID: 7559410.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Phosphatidylinositol (3,4,5)-trisphosphate stimulates phosphorylation of pleckstrin in human platelets. AU - Zhang,J, AU - Falck,J R, AU - Reddy,K K, AU - Abrams,C S, AU - Zhao,W, AU - Rittenhouse,S E, PY - 1995/9/29/pubmed PY - 1995/9/29/medline PY - 1995/9/29/entrez SP - 22807 EP - 10 JF - The Journal of biological chemistry JO - J Biol Chem VL - 270 IS - 39 N2 - We have reported that platelets exposed to thrombin or thrombin receptor-directed ligand activate phospholipase C and rapidly accumulate phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) and phosphatidylinositol (3,4)-bisphosphate (PtdIns(3,4)P2) as a function of the activation of phosphoinositide (PI) 3-kinases in a GTP-binding protein-dependent manner. In such platelets, serine- and threonine-directed phosphorylation of pleckstrin also occurs and has been attributed to protein kinase C activation. We now report that the phosphorylation of pleckstrin is partially dependent upon PI 3-kinase. Pleckstrin phosphorylation in response to thrombin receptor stimulation is progressively susceptible to inhibition by wortmannin, a potent and specific inhibitor of platelet PI 3-kinases. PI 3-kinase thus seems to play a gradually increasing role in promoting pleckstrin phosphorylation. The IC50 for wortmannin in inhibiting SFLLRN-stimulated 3-phosphorylated phosphoinositide accumulation is 10 nM, and that (i.e. 50% of maximum inhibition) for inhibiting pleckstrin phosphorylation is 15 nM. Synthetic PtdIns(3,4,5)P3, when added to saponin-permeabilized (but not intact) platelets, causes wortmannin-insensitive phosphorylation of pleckstrin. PtdIns(3,4,5)P3 also overcomes the inhibition by wortmannin of thrombin- or guanosine 5'-3-O-(thio)trisphosphate-stimulated pleckstrin phosphorylation. In contrast, PtdIns(4,5)P2 or inositol (1,3,4,5)-tetrakisphosphate are ineffective in these respects. The pattern of phosphorylation of pleckstrin activated by PtdIns(3,4,5)P3 is not distinguishable from that of pleckstrin phosphorylated in intact platelets exposed to protein kinase C-activating beta-phorbol myristate acetate, mimicking diacylglycerol. Activation of protein kinase(s) by PtdIns(3,4,5)P3 thus offers a route for pleckstrin phosphorylation in vivo that is an alternative to activation of phospholipase C-->diacylglycerol-->protein kinase C. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/7559410/Phosphatidylinositol__345__trisphosphate_stimulates_phosphorylation_of_pleckstrin_in_human_platelets_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(18)90032-3 DB - PRIME DP - Unbound Medicine ER -