Document Detail

Hsp90 Co-localizes with Rab-GDI-1 and regulates agonist-induced amylase release in AR42J cells.
MedLine Citation:
PMID:  19910677     Owner:  NLM     Status:  MEDLINE    
Rab proteins are small GTPases required for vesicle trafficking through the secretory and endocytic pathways. Rab GDP-dissociation inhibitor (rab-GDI) regulates Rab protein function and localization by maintaining Rab proteins in the GDP-bound conformation. Two isoforms of rab-GDI are present in most mammalian cells: GDI-1 and GDI-2. It has recently been demonstrated that a Heat shock protein 90 (Hsp90) chaperone complex regulates the interactions between Rab proteins and Rab-GDI-1. The AR42J cell line is derived from rat pancreatic exocrine tumor cells and develops an acinar-like phenotype when treated with dexamethasone (Dex). The aim of the present study was to examine the expression of rab-GDI isoforms and Hsp90 in AR42J cells in the presence or absence of Dex. Rab-GDI:Hsp90 interactions were also examined. Both rab-GDI isoforms were detected in AR42J cells by immunoblotting. In Dex-treated cells, quantitative immunoblotting revealed that rab-GDI-1 expression increased by 28%, although this change was not statistically significant. Rab-GDI-2 levels were unaltered by Dex treatment. Approximately 21% rab-GDI-1 was membrane associated, whereas rab-GDI-2 was exclusively cytosolic. Dex treatment did not affect the subcellular distribution of rab-GDI isoforms. Hsp90 was present in the cytosolic and membrane fractions of AR42J cells and co-immunoprecipitated with cytosolic rab-GDI-1. Moreover, density gradient centrifugation of AR42J cell membranes revealed that Hsp90 and rab-GDI-1 co-localize on low- and high-density membrane fractions, including amylase-containing secretory granules. The Hsp90 inhibitor, geldanamycin, inhibited CCK-8-induced amylase release from these cells in a dose-dependent manner. Our results indicate that as AR42J cells differentiate into acinar-like cells, rab-GDI isoform expression and localization is not significantly altered. Moreover, our findings suggest that Hsp90 regulates agonist-induced secretion in exocrine cells by interacting with rab-GDI-1.
Robert Raffaniello; Daria Fedorova; Dawn Ip; Sarwish Rafiq
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-11-04
Journal Detail:
Title:  Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology     Volume:  24     ISSN:  1421-9778     ISO Abbreviation:  Cell. Physiol. Biochem.     Publication Date:  2009  
Date Detail:
Created Date:  2009-11-13     Completed Date:  2010-02-17     Revised Date:  2013-07-31    
Medline Journal Info:
Nlm Unique ID:  9113221     Medline TA:  Cell Physiol Biochem     Country:  Switzerland    
Other Details:
Languages:  eng     Pagination:  369-78     Citation Subset:  IM    
Copyright Information:
2009 S. Karger AG, Basel.
Hunter College, New York, NY 10010, USA.
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MeSH Terms
Amylases / metabolism*
Benzoquinones / pharmacology
Cell Line, Tumor
Centrifugation, Density Gradient
Dexamethasone / pharmacology
Guanine Nucleotide Dissociation Inhibitors / analysis,  metabolism*
HSP90 Heat-Shock Proteins / analysis,  metabolism*
Lactams, Macrocyclic / pharmacology
Protein Isoforms / analysis,  metabolism
Sincalide / metabolism
rab GTP-Binding Proteins / analysis,  metabolism*
rho-Specific Guanine Nucleotide Dissociation Inhibitors
Grant Support
1 R15 GM076034-01/GM/NIGMS NIH HHS
Reg. No./Substance:
0/Benzoquinones; 0/GDI-2 protein, rat; 0/GDP dissociation inhibitor 1; 0/Guanine Nucleotide Dissociation Inhibitors; 0/HSP90 Heat-Shock Proteins; 0/Lactams, Macrocyclic; 0/Protein Isoforms; 0/rho-Specific Guanine Nucleotide Dissociation Inhibitors; 25126-32-3/Sincalide; 50-02-2/Dexamethasone; EC 3.2.1.-/Amylases; EC 3.6.1.-/rab GTP-Binding Proteins; Z3K3VJ16KU/geldanamycin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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