Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1

Receptor-mediated platelet activation requires phospholipase C (PLC) activity to elevate intracellular calcium and induce actin cytoskeleton reorganization. PLCs are classified into structurally distinct β, γ, δ, ε, ζ, and η isoforms. There are two PLCγ isoforms (PLCγ1, PLCγ2), which are critical fo...

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Main Authors:	Zheng, Yongwei, Adams, Tamara, Zhi, Huiying, Yu, Mei, Wen, Renren, Newman, Peter J., Wang, Demin, Newman, Debra K.
Format:	Online
Language:	English
Published:	Public Library of Science 2015
Online Access:	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4368822/

id	pubmed-4368822
recordtype	oai_dc
spelling	pubmed-43688222015-03-27 Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1 Zheng, Yongwei Adams, Tamara Zhi, Huiying Yu, Mei Wen, Renren Newman, Peter J. Wang, Demin Newman, Debra K. Research Article Receptor-mediated platelet activation requires phospholipase C (PLC) activity to elevate intracellular calcium and induce actin cytoskeleton reorganization. PLCs are classified into structurally distinct β, γ, δ, ε, ζ, and η isoforms. There are two PLCγ isoforms (PLCγ1, PLCγ2), which are critical for activation by tyrosine kinase-dependent receptors. Platelets express both PLCγ1 and PLCγ2. Although PLCγ2 has been shown to play a dominant role in platelet activation, the extent to which PLCγ1 contributes has not been evaluated. To ascertain the relative contributions of PLCγ1 and PLCγ2 to platelet activation, we generated conditionally PLCγ1-deficient, wild-type (WT), PLCγ2-deficient, and PLCγ1/PLCγ2 double-deficient mice and measured the ability of platelets to respond to different agonists. We found that PLCγ2 deficiency abrogated αIIbβ3-dependent platelet spreading, GPVI-dependent platelet aggregation, and thrombus formation on collagen-coated surfaces under shear conditions, which is dependent on both GPVI and αIIbβ3. Addition of exogenous ADP overcame defective spreading of PLCγ2-deficient platelets on immobilized fibrinogen, suggesting that PLCγ2 is required for granule secretion in response to αIIbβ3 ligation. Consistently, αIIbβ3-mediated release of granule contents was impaired in the absence of PLCγ2. In contrast, PLCγ1-deficient platelets spread and released granule contents normally on fibrinogen, exhibited normal levels of GPVI-dependent aggregation, and formed thrombi normally on collagen-coated surfaces. Interestingly, enforced expression of PLCγ1 fully restored GPVI-dependent aggregation and αIIbβ3-dependent spreading of PLCγ2-deficient platelets. We conclude that platelet activation through GPVI and αIIbβ3 utilizes PLCγ2 because PLCγ1 levels are insufficient to support responsiveness, but that PLCγ1 can restore responsiveness if expressed at levels normally achieved by PLCγ2. Public Library of Science 2015-03-20 /pmc/articles/PMC4368822/ /pubmed/25793864 http://dx.doi.org/10.1371/journal.pone.0119739 Text en © 2015 Zheng et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
repository_type	Open Access Journal
institution_category	Foreign Institution
institution	US National Center for Biotechnology Information
building	NCBI PubMed
collection	Online Access
language	English
format	Online
author	Zheng, Yongwei Adams, Tamara Zhi, Huiying Yu, Mei Wen, Renren Newman, Peter J. Wang, Demin Newman, Debra K.
spellingShingle	Zheng, Yongwei Adams, Tamara Zhi, Huiying Yu, Mei Wen, Renren Newman, Peter J. Wang, Demin Newman, Debra K. Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1
author_facet	Zheng, Yongwei Adams, Tamara Zhi, Huiying Yu, Mei Wen, Renren Newman, Peter J. Wang, Demin Newman, Debra K.
author_sort	Zheng, Yongwei
title	Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1
title_short	Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1
title_full	Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1
title_fullStr	Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1
title_full_unstemmed	Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1
title_sort	restoration of responsiveness of phospholipase cγ2-deficient platelets by enforced expression of phospholipase cγ1
description	Receptor-mediated platelet activation requires phospholipase C (PLC) activity to elevate intracellular calcium and induce actin cytoskeleton reorganization. PLCs are classified into structurally distinct β, γ, δ, ε, ζ, and η isoforms. There are two PLCγ isoforms (PLCγ1, PLCγ2), which are critical for activation by tyrosine kinase-dependent receptors. Platelets express both PLCγ1 and PLCγ2. Although PLCγ2 has been shown to play a dominant role in platelet activation, the extent to which PLCγ1 contributes has not been evaluated. To ascertain the relative contributions of PLCγ1 and PLCγ2 to platelet activation, we generated conditionally PLCγ1-deficient, wild-type (WT), PLCγ2-deficient, and PLCγ1/PLCγ2 double-deficient mice and measured the ability of platelets to respond to different agonists. We found that PLCγ2 deficiency abrogated αIIbβ3-dependent platelet spreading, GPVI-dependent platelet aggregation, and thrombus formation on collagen-coated surfaces under shear conditions, which is dependent on both GPVI and αIIbβ3. Addition of exogenous ADP overcame defective spreading of PLCγ2-deficient platelets on immobilized fibrinogen, suggesting that PLCγ2 is required for granule secretion in response to αIIbβ3 ligation. Consistently, αIIbβ3-mediated release of granule contents was impaired in the absence of PLCγ2. In contrast, PLCγ1-deficient platelets spread and released granule contents normally on fibrinogen, exhibited normal levels of GPVI-dependent aggregation, and formed thrombi normally on collagen-coated surfaces. Interestingly, enforced expression of PLCγ1 fully restored GPVI-dependent aggregation and αIIbβ3-dependent spreading of PLCγ2-deficient platelets. We conclude that platelet activation through GPVI and αIIbβ3 utilizes PLCγ2 because PLCγ1 levels are insufficient to support responsiveness, but that PLCγ1 can restore responsiveness if expressed at levels normally achieved by PLCγ2.
publisher	Public Library of Science
publishDate	2015
url	https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4368822/
_version_	1613201868927795200

Restoration of Responsiveness of Phospholipase Cγ2-Deficient Platelets by Enforced Expression of Phospholipase Cγ1

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