Regulation of involucrin gene expression by calcium in normal human keratinocytes.
Calcium is essential for normal epidermal differentiation. Data from Northern and nuclear run-on analysis indicate that involucrin gene transcription is induced by 1.2 mM extracellular calcium. A 3.7 Kbp fragment of the involucrin gene, which contains 2.5 Kbp of upstream region, the transcription start site, and the first intron, was sub-cloned into the pGL3-basic luciferase reporter vector and transfected into pre-confluent normal human keratinocytes (NHK). The stimulated activities of this clone were above basal levels and was further enhanced eight-fold by 1.2 mM extracelluar calcium. The results from a series of truncation and internal deletion experiments revealed multiple calcium-independent enhancer elements between -2476 and -2131 bp of the transcription start site and a calcium-dependent element between -2131 and -2028 bp. This 103 bp fragment contains sequences of an AP-1 site (TGAGTCA), a SP-1 site (GGGCGG), and shares homology with two elements in the human keratin-1 promoter, within the regions identified as mediating the calcium responsiveness of that gene in keratinocytes. One or more of these putative elements may be involved in the calcium-dependent regulation of the involucrin gene transcription in NHK.
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Endocrine Unit, VA Medical Center, University of California, 4150 Clement Street, 111N, San Francisco, CA 94121, USA.
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Kim
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D024506:5' Flanking Region; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D004742:Enhancer Elements, Genetic; D006801:Humans; D007231:Infant, Newborn; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation
D011498:Protein Precursors; C032253:involucrin; D002118:Calcium