Transcriptional regulators of expression of K#16, the disease-associated keratin.
In most malignant and benign skin diseases, the normal pattern of keratin expression is altered. Among other phenotypic changes, the expression of hyperproliferation- and activation-associated keratins K#16 and K#6 is induced. Because the molecular mechanisms and the nuclear regulators involved in this induction are unknown, we have characterized the transcriptional regulators of expression of the keratin K#16 promoter. Our previous studies have shown that the transcription of K#16 is strongly and specifically induced in epidermal keratinocytes by epidermal growth factor (EGF), through the EGF-responsive element (RE). In the present work, using an electrophoretic mobility-shift assay, we have found several nuclear protein binding sites that have been identified as an Sp1 site, an AP2 site, the EGF-RE, and an enhancer element. The function of each site was assessed in transfection assays using specific deletions. Both the Sp1 and EGF-RE sites are essential for K#16 promoter activity. The site that functions as an independent enhancer, E, was found adjacent to and interacting with a sequence recognized by the AP2 transcription factor. This knowledge of the nuclear regulators of expression of the disease-associated K#16 keratin provides insight into the molecular parameters that might be important in skin diseases.
Magnaldo
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Ronald O. Perelman Department of Dermatology, NYU Medical Center, New York 10016.
Bernerd
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Freedberg
I M
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Ohtsuki
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Blumenberg
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D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004742:Enhancer Elements, Genetic; D004815:Epidermal Growth Factor / Q000378:metabolism; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D007633:Keratins / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion; D012871:Skin Diseases / Q000235:genetics* / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D016329:Sp1 Transcription Factor; D050656:Transcription Factor AP-2; D014157:Transcription Factors; D004815:Epidermal Growth Factor; D007633:Keratins; D004247:DNA