Document Detail


Multiple elements in the upstream glucokinase promoter contribute to transcription in insulinoma cells.
MedLine Citation:
PMID:  1406648     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
beta-cell type-specific expression of the upstream glucokinase promoter was studied by transfection of fusion genes and analysis of DNA-protein interactions. A construct containing 1,000 bp of 5'-flanking DNA was efficiently expressed in HIT M2.2.2 cells, a beta-cell-derived line that makes both insulin and glucokinase, but not in NIH 3T3 cells, a heterologous cell line. In a series of 5' deletion mutations between bases -1000 and -100 (relative to a base previously designated +1), efficient expression in HIT cells was maintained until -280 bp, after which transcription decreased in a stepwise manner. The sequences between -180 and -1 bp contributing to transcriptional activity in HIT cells were identified by studying 28 block transversion mutants that spanned this region in 10-bp steps. Two mutations reduced transcription 10-fold or more, while six reduced transcription between 3- and 10-fold. Three mutationally sensitive regions of this promoter were found to bind to a factor that was expressed preferentially in pancreatic islet beta cells. The binding sites, designated upstream promoter elements (UPEs), shared a consensus sequence of CAT(T/C)A(C/G). Methylation of adenine and guanine residues within this sequence prevented binding of the beta-cell factor, as did mutations at positions 2, 3, and 5. Analysis of nuclear extracts from different cell lines identified UPE-binding activity in HIT M2.2.2 and beta-TC-3 cells but not in AtT-20, NIH 3T3, or HeLa cells; the possibility of a greatly reduced amount in alpha-TC-6 cells could not be excluded. UV laser cross-linking experiments supported the beta-cell type expression of this factor and showed it to be approximately 50 kDa in size. Gel mobility shift competition experiments showed that this beta-cell factor is the same that binds to similar elements, termed CT boxes, in the insulin promoter. Thus, a role for these elements (UPEs or CT boxes), and the beta-cell factor that binds to them, in determining the expression of genes in the beta cells of pancreatic islets is suggested.
Authors:
K D Shelton; A J Franklin; A Khoor; J Beechem; M A Magnuson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Molecular and cellular biology     Volume:  12     ISSN:  0270-7306     ISO Abbreviation:  Mol. Cell. Biol.     Publication Date:  1992 Oct 
Date Detail:
Created Date:  1992-10-26     Completed Date:  1992-10-26     Revised Date:  2010-09-07    
Medline Journal Info:
Nlm Unique ID:  8109087     Medline TA:  Mol Cell Biol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  4578-89     Citation Subset:  IM    
Affiliation:
Department of Molecular Physiology, Vanderbilt University Medical School, Nashville, Tennessee 37232.
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MeSH Terms
Descriptor/Qualifier:
3T3 Cells
Animals
Base Sequence
Cloning, Molecular
Cricetinae
DNA
Gene Expression Regulation, Enzymologic
Glucokinase / genetics*,  metabolism
Insulin / genetics
Insulinoma
Islets of Langerhans / enzymology*
Mice
Molecular Sequence Data
Mutagenesis
Organ Specificity / genetics
Promoter Regions, Genetic*
Transcription Factors / metabolism
Transcription, Genetic*
Transfection
Tumor Cells, Cultured
Grant Support
ID/Acronym/Agency:
DK42502/DK/NIDDK NIH HHS; DK42612/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Transcription Factors; 11061-68-0/Insulin; 9007-49-2/DNA; EC 2.7.1.2/Glucokinase
Comments/Corrections

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


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