title: The minimal promoter region of the dense-core vesicle protein IA-2: transcriptional regulation by CREB.
abstract: OBJECTIVE
  IA-2 is a transmembrane protein found in the dense-core vesicles (DCV) of neuroendocrine cells and one of the major autoantigens in type 1 diabetes. DCV are involved in the secretion of hormones (e.g., insulin) and neurotransmitters. Stimulation of pancreatic β cells with glucose upregulates the expression of IA-2 and an increase in IA-2 results in an increase in the number of DCV. Little is known, however, about the promoter region of IA-2 or the transcriptional factors that regulate the expression of this gene.
  
  
  METHODS
  In the present study, we constructed eight deletion fragments from the upstream region of the IA-2 transcription start site and linked them to a luciferase reporter.
  
  
  RESULTS
  By this approach, we have identified a short bp region (-216 to +115) that has strong promoter activity. We also identified a transcription factor, cAMP responsive element-binding protein (CREB), which binds to two CREB-related binding sites located in this region. The binding of CREB to these sites enhanced IA-2 transcription by more than fivefold. We confirmed these findings by site-directed mutagenesis, chromatin immunoprecipitation assays and RNAi inhibition.
  
  
  CONCLUSIONS
  Based on these findings, we conclude that the PKA pathway is a critical, but not the exclusive signaling pathway involved in IA-2 gene expression.
authors.affiliation: Experimental Medicine Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research (NIDCR), National Institutes of Health (NIH), B30/Rm106, Bethesda, MD, 20892, USA, tcai@mail.nih.gov.
authors.forename: Tao
authors.initials: T
authors.lastname: Cai
authors.forename: Hiroki
authors.initials: H
authors.lastname: Hirai
authors.forename: Huanyu
authors.initials: H
authors.lastname: Xu
authors.forename: Abner L
authors.initials: AL
authors.lastname: Notkins
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D050882:CREB-Binding Protein / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8 / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D050882:CREB-Binding Protein; C516862:PTPRN protein, human; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8