Document Detail


Differential expression of rat insulin I and II messenger ribonucleic acid after prolonged exposure of islet beta-cells to elevated glucose levels.
MedLine Citation:
PMID:  9449616     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Prolonged exposure of rat islet beta-cells to 10 mmol/liter glucose has been previously shown to activate more cells into a glucose-responsive state (>90%) than has exposure to 6 mmol/liter glucose (50%). The present study demonstrates that this recruitment of more activated cells results in 4- to 6-fold higher levels of proinsulin I and proinsulin II messenger RNA (mRNA). However, only the rate of proinsulin I synthesis is increased. Failure to increase the rate of proinsulin II synthesis in the glucose-activated cells results in cellular depletion of the insulin II isoform, which can be responsible for degranulation of beta-cells cultured at 10 mmol/liter glucose. Higher glucose levels (20 mmol/liter) during culture did not correct this dissociation between the stimulated insulin I formation and the nonstimulated insulin II formation. On the contrary, the rise from 10 to 20 mmol/liter glucose resulted in a 2-fold reduction in the levels of proinsulin II mRNA, but not of proinsulin I mRNA; this process further increased the ratio of insulin I over insulin II to 5-fold higher values than those in freshly isolated beta-cells. The present data suggest that an elevated insulin I over insulin II ratio in pancreatic tissue is a marker for a prolonged exposure to elevated glucose levels. The increased ratio in this condition results from a transcriptional and/or a posttranscriptional failure in elevating insulin II formation while insulin I production is stimulated in the glucose-activated beta-cells.
Authors:
Z Ling; H Heimberg; A Foriers; F Schuit; D Pipeleers
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Endocrinology     Volume:  139     ISSN:  0013-7227     ISO Abbreviation:  Endocrinology     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1998-02-18     Completed Date:  1998-02-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0375040     Medline TA:  Endocrinology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  491-5     Citation Subset:  AIM; IM    
Affiliation:
Diabetes Research Center, Vrije Universiteit Brussel, Brussels, Belgium.
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MeSH Terms
Descriptor/Qualifier:
Animals
Cells, Cultured
Glucose / metabolism*
Insulin / genetics*,  metabolism
Islets of Langerhans / metabolism*
Isomerism
RNA, Messenger / metabolism*
Rats
Rats, Wistar
Time Factors
Chemical
Reg. No./Substance:
0/RNA, Messenger; 11061-68-0/Insulin; 50-99-7/Glucose

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


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