ATF-2 stimulates the human insulin promoter through the conserved CRE2 sequence

Colin William Hay, Laura A. Ferguson, Kevin Docherty

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The insulin promoter contains a number of dissimilar cis-acting regulatory elements that bind a range of tissue specific and ubiquitous transcription factors. Of the regulatory elements within the insulin promoter, the cyclic AMP responsive element (CRE) binds by far the most diverse array of transcription factors. Rodent insulin promoters have a single CRE site, whereas there are four CREs within the human insulin gene, of which CRE2 is the only one conserved between species. The aim of this study was to characterise the human CRE2 site and to investigate the effects of the two principal CRE-associated transcription factors; CREB-1 and ATF-2. Co-transfection of INS-1 pancreatic beta-cells with promoter constructs containing the human insulin gene promoter placed upstream of the firefly luciferase reporter gene and expression plasmids for ATF-2 or CREB-1 showed that ATF-2 stimulated transcriptional activity while CREB-1 elicited an inhibitory effect. Mutagenesis of CRE2 diminished the effect of ATF-2 but not that of CREB-1. ATF-2 was shown to bind to the CRE2 site by electrophoretic mobility shift assay and by chromatin immunoprecipitation, while siRNA mediated knockdown of ATF-2 diminished the stimulatory effects of cAMP related signalling on promoter activity. These results suggest that ATF-2 may be a key regulator of the human insulin promoter possibly stimulating activity in response to extracellular signals.

Original languageEnglish
Pages (from-to)79-91
Number of pages13
JournalBiochimica et Biophysica Acta (BBA) - Gene Structure and Expression
Volume1769
Issue number2
Early online date28 Jan 2007
DOIs
Publication statusPublished - Feb 2007

Keywords

  • diabetes mellitus
  • cAMP responsive element
  • gene transcription
  • insulin gene
  • element-binding-protein
  • activating transcription factor-2
  • pancreatic beta-cells
  • P38 map kinase
  • gene-transcrition
  • somatostatin promoter
  • islet cells
  • I gene
  • phosphorylation

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