Document Detail

Expression and distribution of lactate/monocarboxylate transporter isoforms in pancreatic islets and the exocrine pancreas.
MedLine Citation:
PMID:  11272148     Owner:  NLM     Status:  MEDLINE    
Transport of lactate across the plasma membrane of pancreatic islet beta-cells is slow, as described by Sekine et al. (J Biol Chem 269:4895-4902, 1994), which is a feature that may be important for normal nutrient-induced insulin secretion. Although eight members of the monocarboxylate transporter (MCT) family have now been identified, the expression of these isoforms within the exocrine and endocrine pancreas has not been explored in detail. Using immunocytochemical analysis of pancreatic sections fixed in situ, we demonstrated three phenomena. First, immunoreactivity of the commonly expressed lactate transporter isoform MCT1 is near zero in both alpha- and beta-cells but is abundant in the pancreatic acinar cell plasma membrane. No MCT2 or MCT4 was detected in any pancreatic cell type. Second, Western analysis of purified beta- and non-beta-cell membranes revealed undetectable levels of MCT1 and MCT4. In derived beta-cell lines, MCT1 was absent from MIN6 cells and present in low amounts in INS-1 cell membranes and at high levels in RINm5F cells. MCT4 was weakly expressed in MIN6 beta-cells. Third, CD147, an MCT-associated chaperone protein, which is closely colocalized with MCT1 on acinar cell membranes, was absent from islet cell membranes. CD147 was also largely absent from MIN6 and INS-1 cells but abundant in RINm5F cells. Low expression of MCT1, MCT2, and MCT4 contributes to the enzymatic configuration of beta-cells, which is poised to ensure glucose oxidation and the generation of metabolic signals and may also be important for glucose sensing in islet non-beta-cells. MCT overexpression throughout the islet could contribute to deranged hormone secretion in some forms of type 2 diabetes.
C Zhao; M C Wilson; F Schuit; A P Halestrap; G A Rutter
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Diabetes     Volume:  50     ISSN:  0012-1797     ISO Abbreviation:  Diabetes     Publication Date:  2001 Feb 
Date Detail:
Created Date:  2001-02-22     Completed Date:  2001-03-29     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372763     Medline TA:  Diabetes     Country:  United States    
Other Details:
Languages:  eng     Pagination:  361-6     Citation Subset:  AIM; IM    
Department of Biochemistry, School of Medical Sciences, University of Bristol, UK.
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MeSH Terms
Anion Transport Proteins
Blotting, Western
COS Cells
Carrier Proteins / metabolism*
Cell Line
Islets of Langerhans / cytology,  metabolism*
Lactic Acid / metabolism*
Pancreas / metabolism*
Protein Isoforms / metabolism
Rats, Wistar
Tissue Distribution
Reg. No./Substance:
0/Anion Transport Proteins; 0/Carrier Proteins; 0/Protein Isoforms; 50-21-5/Lactic Acid

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

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