Document Detail

Decreased PMCA4b expression has no effect on calcium homeostasis in Meg-01 cells.
MedLine Citation:
PMID:  12944246     Owner:  NLM     Status:  MEDLINE    
PMCA (plasma membrane calcium ATPase) is an energy-driven membrane transporter that pumps calcium out of the cell cytosol. Stable resting calcium and highly regulated cytosolic calcium fluxes must be maintained for proper cellular function. The primary function of PMCA in calcium homeostasis is to regulate the steady-state calcium concentration while cells are still at rest. We examined the effects of stable production of antisense RNAs targeted to the PMCA subtype 4b (PMCA4b) on cultured human megakaryoblastic (Meg-01) cells. The expression of PMCA-4b in these cells was diminished by approximately 50% as assessed by Western immunoblotting and in vitro ATPase assay. It was also determined that endogenous expression of PMCA1b in these cells was at a level such as that it can not be detected by Western immunoblotting. The rate of calcium efflux catalyzed by PMVA4b was inhibited in cells with decreased PMCA4b expression by approximately 60%. However, there was no difference in extrusion rate when sarco(endo)plasmic reticular ATPases (SERCA) were not functional. The resting levels of intracellular calcium concentrations in these cells were also not distinguishable from those of wild-type cells. These results suggest that a decrease in PMCA expression in Meg-01 cells is compensated to maintain normal intracellular calcium levels.
Tina C Wan; William L Dean
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Platelets     Volume:  14     ISSN:  0953-7104     ISO Abbreviation:  Platelets     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-08-28     Completed Date:  2004-05-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9208117     Medline TA:  Platelets     Country:  England    
Other Details:
Languages:  eng     Pagination:  295-303     Citation Subset:  IM    
Department of Pharmacy and Toxicology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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MeSH Terms
Calcium / metabolism*
Calcium Signaling
Calcium-Transporting ATPases / antagonists & inhibitors,  biosynthesis,  physiology*
Cation Transport Proteins
Cell Line
DNA, Antisense / pharmacology
Megakaryocytes / cytology,  metabolism
Plasma Membrane Calcium-Transporting ATPases
Thrombin / pharmacology
Reg. No./Substance:
0/Cation Transport Proteins; 0/DNA, Antisense; 7440-70-2/Calcium; EC; EC ATPases; EC Membrane Calcium-Transporting ATPases

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