PDX-1 interaction and regulation of the Pancreatic Derived Factor (PANDER, FAM3B) promoter

Biochim Biophys Acta. 2008 Oct;1779(10):645-51. doi: 10.1016/j.bbagrm.2008.07.007. Epub 2008 Jul 29.

Abstract

Pancreatic Derived Factor (PANDER) is a novel cytokine-like protein dominantly expressed within the endocrine pancreas. Our previous study demonstrated that the PANDER promoter was both tissue-specific and glucose-responsive. Surrounding the PANDER transcriptional start site are several putative A- and E-Box elements that may bind to the various pancreatic transcriptional factors of MafA, BETA2/NeuroD, and Pancreatic Duodenal Homeobox-1 (PDX-1). To characterize the transcriptional regulatory factors involved in PANDER gene expression, we performed co-transfection reporter gene analysis and demonstrated upregulation by all three transcription factors, with the greatest individual increase stemming from PDX-1. Potential binding of PDX-1 to A box (TAAT) regions of the PANDER promoter was demonstrated by chromatin immunoprecipitation (ChIP) and further corroborated by electrophoretic mobility shift assay (EMSA). Binding of PDX-1 to the A box regions was inhibited by mutagenized (TAGT) oligonucleotides. Site-directed mutagenesis of the three PDX-1 A box binding motifs revealed that A box sites 2 and 3 in combination were critical for maximal gene expression and deletion resulted in a 82% reduction in promoter activity. Furthermore, deletion of A box sites 2 and 3 completely diminished the glucose-responsiveness of the PANDER promoter. Our findings demonstrate that PANDER is a potential PDX-1 target gene and the A box sites within the promoter region are critical for basal and glucose-stimulated PANDER expression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites / genetics
  • Cytokines / genetics*
  • Cytokines / metabolism
  • Gene Expression Regulation* / drug effects
  • Glucose / pharmacology
  • Homeodomain Proteins / chemistry
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism*
  • Homeodomain Proteins / physiology*
  • Insulin-Secreting Cells / metabolism
  • Mice
  • Mutagenesis, Site-Directed
  • NIH 3T3 Cells
  • Organ Specificity / genetics
  • Promoter Regions, Genetic*
  • Protein Binding / genetics
  • Protein Structure, Tertiary / genetics
  • Trans-Activators / chemistry
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Trans-Activators / physiology*
  • Tumor Cells, Cultured

Substances

  • Cytokines
  • Homeodomain Proteins
  • PANDER protein, mouse
  • Trans-Activators
  • pancreatic and duodenal homeobox 1 protein
  • Glucose