Document Detail

(-)-Epigallocatechin gallate attenuates the induction of HSP27 stimulated by sphingosine 1-phosphate via suppression of phosphatidylinositol 3-kinase/Akt pathway in osteoblasts.
MedLine Citation:
PMID:  19578793     Owner:  NLM     Status:  MEDLINE    
We previously reported that sphingosine 1-phosphate stimulates the induction of heat shock protein 27 (HSP27) through p38 mitogen-activated protein (MAP) kinase and phosphatidylinositol 3-kinase/Akt in osteoblast-like MC3T3-E1 cells. In the present study, we investigated whether (-)-epigallocatechin gallate (EGCG), the major polyphenol found in green tea, affects the induction of HSP27 in these cells and its mechanism, since it was previously reported that catechin, including EGCG, suppresses bone resorption. EGCG significantly reduced the induction of HSP27 stimulated by sphingosine 1-phosphate in a dose-dependent manner between 10 and 30 microM. Immunofluorescence microscopy studies revealed that sphingosine 1-phosphate certainly stimulated the induction of HSP27 in the cytosol of these cells, and that EGCG clearly suppressed its induction. However, sphingosine 1-phosphate-stimulated phosphorylation of p38 MAP kinase or MAPKAP-2 was not affected by EGCG. By contrast, EGCG markedly suppressed the phosphorylations of both Akt and glycogen synthase kinase-3beta stimulated by sphingosine 1-phosphate. These results strongly suggest that EGCG suppresses the induction of HSP27 stimulated by sphingosine 1-phosphate via attenuation of, not the p38 MAP kinase pathway, but of the phosphatidylinositol 3-kinase/Akt pathway in osteoblasts.
Hideo Natsume; Seiji Adachi; Shinji Takai; Haruhiko Tokuda; Rie Matsushima-Nishiwaki; Chiho Minamitani; Junichi Yamauchi; Kanefusa Kato; Jun Mizutani; Osamu Kozawa; Takanobu Otsuka
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International journal of molecular medicine     Volume:  24     ISSN:  1107-3756     ISO Abbreviation:  Int. J. Mol. Med.     Publication Date:  2009 Aug 
Date Detail:
Created Date:  2009-07-06     Completed Date:  2009-09-24     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  9810955     Medline TA:  Int J Mol Med     Country:  Greece    
Other Details:
Languages:  eng     Pagination:  197-203     Citation Subset:  IM    
Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
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MeSH Terms
1-Phosphatidylinositol 3-Kinase / metabolism*
Animals, Newborn
Blotting, Western
Catechin / analogs & derivatives*,  pharmacology
Cell Line
Cells, Cultured
Dose-Response Relationship, Drug
HSP27 Heat-Shock Proteins / metabolism*
Intracellular Signaling Peptides and Proteins / metabolism
Lysophospholipids / pharmacology*
Microscopy, Fluorescence
Models, Biological
Osteoblasts / cytology,  drug effects*,  metabolism
Phosphorylation / drug effects
Protein-Serine-Threonine Kinases / metabolism
Proto-Oncogene Proteins c-akt / metabolism*
Signal Transduction / drug effects
Sphingosine / analogs & derivatives*,  pharmacology
p38 Mitogen-Activated Protein Kinases / metabolism
Reg. No./Substance:
0/HSP27 Heat-Shock Proteins; 0/Intracellular Signaling Peptides and Proteins; 0/Lysophospholipids; 123-78-4/Sphingosine; 154-23-4/Catechin; 26993-30-6/sphingosine 1-phosphate; 989-51-5/epigallocatechin gallate; EC 2.7.1.-/MAP-kinase-activated kinase 2; EC 3-Kinase; EC Kinases; EC Proteins c-akt; EC Mitogen-Activated Protein Kinases

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