Regulation of IL-1 alpha expression in human keratinocytes: transcriptional activation of the IL-1 alpha gene by TNF-alpha, LPS, and IL-1 alpha.

Abstract

Epidermal epithelial cells (keratinocytes) produce IL-1 alpha potentially relevant for mechanisms of microbial invasion, inflammation, immunological reactions, and tissue injury in the skin. We investigated the regulation of IL-1 alpha expression by human keratinocytes. RIA showed that TNF-alpha, LPS, and PMA caused a marked accumulation of IL-1 alpha Ag in keratinocyte lysates and supernatants after 2 h of exposure. Northern blot analyses demonstrated that TNF-alpha, IL-1 alpha, and LPS transiently increased the steady-state levels of IL-1 alpha mRNA by 8-fold, 10-fold, and 6-fold, respectively, at 2 h. Nuclear run-on transcription studies with isolated nuclei from cells treated with TNF-alpha, IL-1 alpha, and LPS showed that the transcription rate of the IL-1 alpha gene increased 6-fold, 6.5-fold, and 4-fold, respectively, after 2 h of treatment. PMA led to a more sustained accumulation of IL-1 alpha mRNA and had no effect on the transcription rate of the IL-1 alpha gene. The 5' region of the IL-1 alpha gene between base pairs -105 and +724 was linked to the luciferase reporter gene and used in transient expression studies. LPS stimulated luciferase activity from the chimeric gene, suggesting that the 5' region of the IL-1 alpha gene tested may, in part, include a responsive sequence to LPS.(ABSTRACT TRUNCATED AT 250 WORDS)