Author/Editor		Rao, Larmi S; Long, Wendy S; Kaneko, Takehiko; Blumenberg, Miroslav
Title		Regulation of transcription factor activity by extracellular signals in epidermal keratinocytes
Type		članek
Source		Acta Dermatovenerol Alp Pannon Adriat
Vol. and No.		Letnik 12, št. 1
Publication year		2003
Volume		str. 3-14
Language		eng
Abstract		Environmental signals, such as growth factors and cytokines, modulate the activity of nuclear transcription factors, thus regulating gene expression. This regulation is of particular importance in skin where a large variety of signals, especially in activated keratinocytes associated with disease states or wound healing, stimulate new gene expression in keratinocytes. In this study, we used electrophoretic mobilityshift assays (EMSA) to define the changes in DNA binding activity of transcription factors in such activated keratinocytes. Normal human epidermal keratinocytes were grown in a serum-free medium and treated with 10% fetal calf serum, EGF, TNFalpha or Oncostatin M (OsM) for different periods of time. Wholecell extracts, without purification of the nuclei, were prepared and combined with a series of 32-P-labeled synthetic oligonucleotide probes containing consensus binding sequences for the transcription factors AP1, NF, C/EBPbeta, and Sp1. Serum activates all four transcription factors in keratinocytes; TNFalpha activates APi, NF and C/EBPbeta, but not Spi, whereas EGF activates AP1 and NF, but not C/EBP/beta or Sp1. On the other hand, OsM specifically activates Sp1. The activation of transcription factors is transient, usually reaching a peak 20 to 60 minutes after stimulation and returning to the basal level after two hours. We conclude that different signaling pathways are activated in response to various extracellular signals. This orchestrates the activity of transcription factors on the promoters of regulated genes in epidermis thus determining the levels of gene expression.
Descriptors		KERATINOCYTES TRANSCRIPTION FACTORS GROWTH SUBSTANCES TRANSCRIPTION FACTOR AP-1 TRANSCRIPTION FACTOR, SP1 NF-KAPPA B PROTO-ONCOGENE PROTEINS C-FOS PROTO-ONCOGENE PROTEINS C-JUN TUMOR NECROSIS FACTOR ELECTROPHORESIS, POLYACRYLAMIDE GEL BLOTTING, WESTERN