Pancreatic and duodenal homeobox 1 (PDX1) phosphorylation at serine-269 is HIPK2-dependent and affects PDX1 subnuclear localization

Research output: Contribution to journalArticle

Authors

  • Rong An
  • Francesca Semplici
  • Saharnaz Vakhshouri
  • Huai-Xiang Hao
  • Jared Rutter
  • Mario A Pagano
  • Flavio Meggio
  • Lorenzo A Pinna
  • Guy A Rutter

Colleges, School and Institutes

External organisations

  • Imperial College London

Abstract

Pancreatic and duodenal homeobox 1 (PDX1) regulates pancreatic development and mature beta-cell function. We demonstrate by mass spectrometry that serine residue at position 269 in the C-terminal domain of PDX1 is phosphorylated in beta-cells. Besides we show that the degree of phosphorylation, assessed with a phospho-Ser-269-specific antibody, is decreased by elevated glucose concentrations in both MIN6 beta-cells and primary mouse pancreatic islets. Homeodomain interacting protein kinase 2 (HIPK2) phosphorylates PDX1 in vitro; phosphate incorporation substantially decreases in PDX1 S269A mutant. Silencing of HIPK2 led to a 51+/-0.2% decrease in Ser-269 phosphorylation in MIN6 beta-cells. Mutation of Ser-269 to phosphomimetic residue glutamic acid (S269E) or de-phosphomimetic residue alanine (S269A) exerted no effect on PDX1 half-life. Instead, PDX1 S269E mutant displayed abnormal changes in subnuclear localization in response to high glucose. Our results suggest that HIPK2-mediated phosphorylation of PDX1 at Ser-269 might be a regulatory mechanism connecting signals generated by changes in extracellular glucose concentration to downstream effectors via changes in subnuclear localization of PDX1, thereby influencing islet cell differentiation and function.

Details

Original languageEnglish
Pages (from-to)155-61
Number of pages7
JournalBiochemical and Biophysical Research Communications
Volume399
Issue number2
Publication statusPublished - 20 Aug 2010

Keywords

  • Animals, Carrier Proteins/metabolism, Cell Differentiation, Cell Line, Cell Nucleus/metabolism, Glucose/metabolism, Homeodomain Proteins/genetics, Humans, Insulin-Secreting Cells/cytology, Mice, Phosphorylation, Protein Stability, Protein-Serine-Threonine Kinases/metabolism, Serine/genetics, Trans-Activators/genetics