Identification of a functional determinant of differentiation-dependent expression in the involucrin gene.
Involucrin is an integral component of the cornified envelope which is a characteristic feature of the differentiated keratinocyte. Involucrin expression is tightly linked to the onset of differentiation and first expressed in the immediate suprabasal layers of the epidermis. We have identified a transcriptional response element within the distal 5'-flanking region of the involucrin gene which contributes to differentiation-dependent expression. Deletion of this site impairs differentiation-dependent promoter activity in transient transfection analysis, and conversely, this region imparts differentiation-dependent expression to a heterologous promoter. The identified site bears sequence similarity to several AP2-like response elements identified in keratinocyte-specific genes and binds a protein complex (keratinocyte differentiation factor, KDF-1) which is distinct from AP2 by several criteria. The migration of KDF-1 is distinct from AP2 in electrophoretic mobility shift assays, KDF-1 is antigenically unrelated to AP2 since AP2 specific antibodies do not supershift the KDF-1-DNA complex and KDF-1 is poorly competed by oligonucleotides representing consensus AP2 recognition sequences. In addition, the KDF-1 complex is not detected in nuclear extracts derived from human dermal fibroblasts or an enriched population of basal keratinocytes. These findings provide insights to the underlying basis of differentiation-dependent expression of a keratinocyte specific gene.
LaPres
J J
JJ
Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, Illinois 60611, USA.
Hudson
L G
LG
D001665:Binding Sites; D001667:Binding, Competitive; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D006801:Humans; D015603:Keratinocytes / Q000502:physiology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011498:Protein Precursors / Q000235:genetics*; D017422:Sequence Analysis, DNA; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000378:metabolism
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011498:Protein Precursors; D050656:Transcription Factor AP-2; D014157:Transcription Factors; C032253:involucrin