Document Detail


Platelet sarco/endoplasmic reticulum Ca2+ATPase isoform 3b and Rap 1b: interrelation and regulation in physiopathology.
MedLine Citation:
PMID:  9576865     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Platelet Ca2+ signalling involves intracellular Ca2+ pools, whose content is controlled by sarco/endoplasmic reticulum Ca2+ATPases (SERCAs). Among these, a key role is played by the inositol trisphosphate-sensitive Ca2+ pool, associated with the SERCA 3b isoform. We have investigated the control of this Ca2+ pool through the cAMP-dependent phosphorylation of the GTP-binding protein, Rap (Ras-proximate) 1b. We first looked for this Ca2+ pool target of regulation by studying the expression of the different SERCA and Rap 1 proteins in human platelets and various cell lines, by Western blotting and reverse transcription-PCR. Since co-expression of Rap 1b and SERCA 3b was obtained, we looked for their protein-protein interaction as a function of the cAMP-dependent phosphorylation of Rap 1b. Co-immunoprecipitations of SERCA 3b and Rap 1b proteins were found in the absence of phosphorylation, induced by the catalytic subunit of the cAMP-dependent protein kinase (csPKA). In contrast, upon pre-treatment of platelet membranes with csPKA, the SERCA 3b dissociated from the Rap 1b protein, in agreement with a role of its phosphorylated state in their interaction. Finally, we looked for adaptation of this complex in a platelet pathological model of hypertension. We investigated the expression of both proteins, as well as the cAMP-dependent phosphorylation of Rap 1b and SERCA 3b activity in platelets from control normotensive Wistar-Kyoto rats and from spontaneously hypertensive rats (SHRs). A decrease in SERCA 3b activity was associated with a decrease in Rap 1b endogenous phosphorylation in SHR platelets, consistent with a functional role in the regulation of the SERCA 3b-associated Ca2+ pool.
Authors:
C Lacabaratz-Porret; E Corvazier; T Kovàcs; R Bobe; R Bredoux; S Launay; B Papp; J Enouf
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  332 ( Pt 1)     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1998 May 
Date Detail:
Created Date:  1998-08-17     Completed Date:  1998-08-17     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  173-81     Citation Subset:  IM    
Affiliation:
Institut National de la Santé et de la Recherche Médicale U 348, IFR Circulation Lariboisière, Hôpital Lariboisière, 8 rue Guy Patin, 75475 Paris Cedex 10, France.
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MeSH Terms
Descriptor/Qualifier:
Animals
Blood Platelets / enzymology*
Calcium-Transporting ATPases / metabolism*
Cell Line
Cyclic AMP / pharmacology
Endoplasmic Reticulum / enzymology*
GTP-Binding Proteins / physiology*
Gene Expression Regulation, Enzymologic / physiology
Humans
Hypertension / physiopathology
Inositol Phosphates / physiology
Isoenzymes / metabolism
Phosphorylation
RNA, Messenger / metabolism
Rats
Rats, Inbred SHR
Rats, Wistar
Chemical
Reg. No./Substance:
0/Inositol Phosphates; 0/Isoenzymes; 0/RNA, Messenger; 60-92-4/Cyclic AMP; EC 3.6.1.-/GTP-Binding Proteins; EC 3.6.1.8/Calcium-Transporting ATPases
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