Journal article
Nucleo-cytosolic Shuttling of FoxO1 Directly Regulates Mouse Ins2 but Not Ins1 Gene Expression in Pancreatic Beta Cells (MIN6)
The Journal of biological chemistry, Vol.286(15), pp.13647-13656
04/15/2011
DOI: 10.1074/jbc.M110.204248
PMCID: PMC3075709
PMID: 21335550
Abstract
The Forldiead box transcription factor FoxO1 regulates metabolic gene expression in mammals. FoxO1 activity is tightly controlled by phosphatidylinositol 3-kinase (PI3K) signaling, resulting in its phosphorylation and nuclear exclusion. We sought here to determine the mechanisms involved in glucose and insulin-stimulated nuclear shuttling of FoxO1 in pancreatic beta cells and its consequences for preproinsulin (Ins1, Ins2) gene expression. Nuclearlocalized endogenous FoxO1 translocated to the cytosol in response to elevated glucose (3 versus 16.7 mm) in human islet beta cells. Real-time confocal imaging of nucleo-cytosolic shuttling of a FoxO1-EGTP chimera in primary mouse and clonal MIN6 beta cells revealed a time-dependent glucose-responsive nuclear export, also mimicked by exogenous insulin, and blocked by suppressing insulin secretion. Constitutively active PI3K or protein kinase B/Akt exerted similar effects, while inhibitors of PI3K, but not of glycogen synthase kinase-3 or p70 S6 kinase, blocked nuclear export. FoxO1 overexpression reversed the activation by glucose of pancreatic duodenum homeobox-1 (Pdx1) transcription. Silencing of FoxO1 significantly elevated the expression of mouse Ins2, but not Ins1, mRNA at 3 mm glucose. Putative FoxO1 binding sites were identified in the distal promoter of rodent Ins2 genes and direct binding of FoxO1 to the Ins2 promoter was demonstrated by chromatin immunoprecipitation. A 915-bp glucose-responsive Ins2 promoter was inhibited by constitutively active FoxO1, an effect unaltered by simultaneous overexpression of PDX1. We conclude that nuclear import of FoxO1 contributes to the suppression of Pdx1 and ins2 gene expression at low glucose, the latter via a previously unsuspected and direct physical interaction with the Ins2 promoter.
Details
- Title: Subtitle
- Nucleo-cytosolic Shuttling of FoxO1 Directly Regulates Mouse Ins2 but Not Ins1 Gene Expression in Pancreatic Beta Cells (MIN6)
- Creators
- Gargi Meur - Imperial College LondonQingwen Qian - Imperial College LondonGabriela da Silva Xavier - University of LondonTimothy J. Pullen - Imperial College LondonTakashi Tsuboi - The University of TokyoCaroline McKinnon - Imperial College LondonLaura Fletcher - University of BristolJeremy M. Tavare - University of BristolStephen Hughes - John Radcliffe HospitalPaul Johnson - John Radcliffe HospitalGuy A. Rutter - Imperial College London
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.286(15), pp.13647-13656
- DOI
- 10.1074/jbc.M110.204248
- PMID
- 21335550
- PMCID
- PMC3075709
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- Amer Soc Biochemistry Molecular Biology Inc
- Number of pages
- 10
- Grant note
- 067081/Z/02/Z; 081958/Z/07/Z / Wellcome Trust; European Commission 1-2003-235 / Juvenile Diabetes Research Fund (JDRF); Juvenile Diabetes Research Foundation G0401641 / Medical Research Council; UK Research & Innovation (UKRI); Medical Research Council UK (MRC); European Commission Research Leave Fellowship European Union; European Commission BBSRC; UK Research & Innovation (UKRI); Biotechnology and Biological Sciences Research Council (BBSRC) G7708269 / MRC; UK Research & Innovation (UKRI); Medical Research Council UK (MRC) MRC (UK); UK Research & Innovation (UKRI); Medical Research Council UK (MRC)
- Language
- English
- Date published
- 04/15/2011
- Academic Unit
- Anatomy and Cell Biology
- Record Identifier
- 9984420939402771
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