The human involucrin gene is transcriptionally repressed through a tissue-specific silencer element recognized by Oct-2.
Involucrin is an important marker of epithelial differentiation which expression is upregulated just after basal cells are pushed into the suprabasal layer in stratified epithelia. Several transcription factors and regulatory elements had been described as responsible for turning on the gene. However, it is evident that in basal cell layer, additional mechanisms are involved in keeping the gene silent before the differentiation process starts. In this work, we located a potential transcriptional silencer in a 52bp sequence whose integrity is necessary for silencing the proximal enhancer promoter element (PEP) in multiplying keratinocytes. Octamer-binding sites were noticed in this fragment and the specific binding of Oct-2 transcription factor was detected. Oct-2 appears to be implicated in an epithelial-specific repression activity recorded only in keratinocytes and C33-A cell line. Overexpression of Oct-2 repressed the involucrin promoter activity in epithelial cells and in the presence of the silencer element.
Azuara-Liceaga
Elisa
E
Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del I.P.N., Mexico D.F. 07000, Mexico.
Sandoval
Marisol
M
Corona
Matilde
M
Gariglio
Patricio
P
López-Bayghen
Esther
E
D001483:Base Sequence; D002118:Calcium / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D020868:Gene Silencing; D051863:Host Cell Factor C1; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D009841:Oligonucleotides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011498:Protein Precursors / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D012097:Repressor Proteins / Q000378:metabolism; D037941:Silencer Elements, Transcriptional / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D050813:Octamer Transcription Factor-2; D009841:Oligonucleotides; C494165:POU2F1 protein, human; C058435:POU2F2 protein, human; D011498:Protein Precursors; D012097:Repressor Proteins; D014157:Transcription Factors; C032253:involucrin; D002118:Calcium