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

• Published in: Biochemical and biophysical research communications Vol. 399; no. 2; pp. 155 - 161
• Main Authors: An, Rong, da Silva Xavier, Gabriela, Semplici, Francesca, Vakhshouri, Saharnaz, Hao, Huai-Xiang, Rutter, Jared, Pagano, Mario A., Meggio, Flavio, Pinna, Lorenzo A., Rutter, Guy A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 20.08.2010; Academic Press
• Subjects: Animals; Carrier Proteins - metabolism; Cell Differentiation; Cell Line; Cell Nucleus - metabolism; Glucose; Glucose - metabolism; HIPK2; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Humans; Insulin-Secreting Cells - cytology; Insulin-Secreting Cells - metabolism; Islet; Mice; PDX1; Phosphorylation; Protein Serine-Threonine Kinases - metabolism; Protein Stability; Serine - genetics; Serine - metabolism; Trans-Activators - genetics; Trans-Activators - metabolism; β-Cell; PDX1; Phosphorylation; Islet; Glucose; β-Cell; HIPK2
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2010.07.035

► Mouse PDX1 Ser-269 is phosphorylated in pancreatic islets of Langerhans and beta cells. ► High glucose concentration decreases the degree of phosphorylation on PDX1 Ser-269, as assessed by a phospho-specific anti-phospho-Ser269 antibody. ► HIPK2 is a potential kinase for PDX1 Ser-269. ► Phosphorylation at Ser-269 affects the subnuclear distribution of PDX1. Pancreatic and duodenal homeobox 1 (PDX1) regulates pancreatic development and mature β-cell function. We demonstrate by mass spectrometry that serine residue at position 269 in the C-terminal domain of PDX1 is phosphorylated in β-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 β-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 β-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.