Activation of amylin gene transcription by LIM domain homeobox gene isl-1

Mol Endocrinol. 1996 Mar;10(3):243-51. doi: 10.1210/mend.10.3.8833653.


The amylin (IAPP) and insulin genes are coexpressed in the pancreatic beta-cell and share related promoter elements that may bind similar islet transcription factors. The observation that these promoter elements contain AT-rich subdomains suggests that homeobox proteins may be important for the regulation of both insulin and amylin gene transcription. We show here that the LIM domain homeobox protein isl-1 activates the rat amylin promoter in both fibroblast and islet cell lines. Mutation of the rAMY promoter TAAT motifs was associated with a marked reduction in both basal and isl-1 -dependent transcriptional activity. The isl-1 homeodomain binds to the AT-rich AMY element (-156 to -137) in the human amylin (hAMY) gene promoter, and electrophoretic mobility shift assay experiments using isl-1 specific antiserum detected the formation of an hAMY-isl-1 complex using nuclear extract from InR1 -G9 islet cells. Although isl-1 binds to both the insulin and amylin gene promoter elements in vitro, these sequences display marked differences in their relative transcriptional properties when ligated adjacent to a heterologous promoter and transfected into InR1 -G9 islet cells. The insulin gene E2 sequence that binds isl-1 (-230 to -208) functions as a negative element, whereas the hAMY sequence activates the thymidine kinase promoter in islet, but not nonislet, cell lines. Transfection of isl-1-depleted isl-1 (AS)InR1 -G9 cell lines demonstrated that the E2 element continued to repress thymidine kinase promoter activity, whereas the positive transcriptional activity mediated by the AMY element was considerably reduced in isl-1 (AS)-InR1-G9 cell lines. These dat2 demonstrate that highly similar elements in islet hormone gene promoters display differential functional properties and support a role for the isl-1 homeodomain protein in the regulation of amylin, but not insulin, gene transcription.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid / genetics*
  • Animals
  • Binding Sites
  • Cell Line
  • Cricetinae
  • DNA, Antisense / genetics
  • DNA, Recombinant / genetics
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Gene Expression Regulation / drug effects*
  • Genes, Synthetic
  • Homeodomain Proteins / pharmacology*
  • Humans
  • Insulin / genetics
  • Islet Amyloid Polypeptide
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / metabolism
  • LIM-Homeodomain Proteins
  • Mesocricetus
  • Nerve Tissue Proteins*
  • Promoter Regions, Genetic
  • RNA, Messenger / biosynthesis*
  • RNA, Messenger / genetics
  • Rats
  • Recombinant Fusion Proteins / biosynthesis
  • Recombinant Fusion Proteins / genetics
  • Regulatory Sequences, Nucleic Acid
  • Transcription Factors
  • Transcription, Genetic / drug effects*


  • Amyloid
  • DNA, Antisense
  • DNA, Recombinant
  • Homeodomain Proteins
  • Insulin
  • Islet Amyloid Polypeptide
  • LIM-Homeodomain Proteins
  • Nerve Tissue Proteins
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Transcription Factors
  • insulin gene enhancer binding protein Isl-1