title: GW8510 increases insulin expression in pancreatic alpha cells through activation of p53 transcriptional activity.
abstract: BACKGROUND
  Expression of insulin in terminally differentiated non-beta cell types in the pancreas could be important to treating type-1 diabetes. Previous findings led us to hypothesize involvement of kinase inhibition in induction of insulin expression in pancreatic alpha cells.
  
  
  RESULTS
  Alpha (αTC1.6) cells and human islets were treated with GW8510 and other small-molecule inhibitors for up to 5 days. Alpha cells were assessed for gene- and protein-expression levels, cell-cycle status, promoter occupancy status by chromatin immunoprecipitation (ChIP), and p53-dependent transcriptional activity. GW8510, a putative CDK2 inhibitor, up-regulated insulin expression in mouse alpha cells and enhanced insulin secretion in dissociated human islets. Gene-expression profiling and gene-set enrichment analysis of GW8510-treated alpha cells suggested up-regulation of the p53 pathway. Accordingly, the compound increased p53 transcriptional activity and expression levels of p53 transcriptional targets. A predicted p53 response element in the promoter region of the mouse Ins2 gene was verified by chromatin immunoprecipitation (ChIP). Further, inhibition of Jun N-terminal kinase (JNK) and p38 kinase activities suppressed insulin induction by GW8510.
  
  
  CONCLUSIONS
  The induction of Ins2 by GW8510 occurred through p53 in a JNK- and p38-dependent manner. These results implicate p53 activity in modulation of Ins2 expression levels in pancreatic alpha cells, and point to a potential approach toward using small molecules to generate insulin in an alternative cell type.
authors.affiliation: Chemical Biology Program, the Broad Institute of Harvard and MIT, Cambridge, Massachusetts, United States of America.
authors.forename: Dina
authors.initials: D
authors.lastname: Fomina-Yadlin
authors.forename: Stefan
authors.initials: S
authors.lastname: Kubicek
authors.forename: Amedeo
authors.initials: A
authors.lastname: Vetere
authors.forename: Kai Hui Hu
authors.initials: KH
authors.lastname: He
authors.forename: Kaihui Hu
authors.initials: KH
authors.lastname: He
authors.forename: Stuart L
authors.initials: SL
authors.lastname: Schreiber
authors.forename: Bridget K
authors.initials: BK
authors.lastname: Wagner
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D050416:Glucagon-Secreting Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007328:Insulin / Q000378:metabolism*; D051379:Mice; D008875:Middle Aged; D008954:Models, Biological; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D020218:Response Elements / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects* / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: C500810:GW8510; D007211:Indoles; D007328:Insulin; D016159:Tumor Suppressor Protein p53; D051736:Proto-Oncogene Proteins c-mdm2