Regulation of keratinocyte growth factor gene expression in human skin fibroblasts.
Human keratinocyte growth factor (KGF) is a recently identified mitogen for epithelial cells produced by normal stromal fibroblasts. KGF has been shown to stimulate keratinocyte migration and promote re-epithelialization of skin suggesting a critical role for KGF in wound healing. To understand how KGF might be regulated during wound healing, we examined the ability of the pro-inflammatory cytokines interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta) interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) transforming growth factor-beta 1 (TGF-beta 1) and interferon-gamma (IFN-gamma) to modulate KGF gene expression in cultured human fibroblasts, using northern blot analysis. Exposure to IL-1 alpha (20 units/ml) or IL-1 beta (100 units/ml) for 24 h increased KGF mRNA expression by 352% and 504%, respectively, with early induction seen at 2 h and maximal induction seen at 8 h. TNF-alpha (30 ng/ml) increased KGF mRNA expression by 535% at 24 h, with induction first seen at 8 h. The maximal induction of KGF mRNA was observed when IL-1 alpha, IL-1 beta and TNF-alpha were used at 100 units/ml, and 3 ng/ml, respectively, although concentrations 100-500-fold lower (IL-1 alpha, 0.02 units/ml; IL-beta, 0.02 units/ml; and TNF-alpha, 0.03 ng/ml) were nearly as stimulatory, increasing KGF mRNA expression by 175%, 254% and 322%, respectively. IL-6 (200 units/ml), TGF-beta 1 (5 ng/ml) and IFN-gamma (200 units/ml) did not change the level of KGF mRNA at 24 h in human fibroblasts under the same conditions. The protein synthesis inhibitor cycloheximide abrogated the effects of IL-1 alpha, IL-1 beta and TNF-alpha on KGF gene induction, indicating that new protein synthesis is required in the process. Dexamethasone (10(-7) M), known to inhibit inflammatory reactions and retard wound healing, also inhibited the induction of KGF mRNA expression by IL-1 alpha, IL-1 beta and TNF-alpha. Individual variation in KGF mRNA expression was see when fibroblasts from different aged donors were analysed, but no consistent age-associated change was observed. These results suggest that IL-1 alpha, IL-1 beta and TNF-alpha up-regulate KGF gene expression in fibroblasts and might be responsible for its induction following skin wounding or other injury.
Tang
A
A
Department of Dermatology, Boston University School of Medicine, MA 02118 USA.
Gilchrest
B A
BA
D000328:Adult; D000375:Aging / Q000502:physiology; D001483:Base Sequence; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D051526:Fibroblast Growth Factor 10; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D005347:Fibroblasts / Q000502:physiology; D015870:Gene Expression / Q000187:drug effects; D005786:Gene Expression Regulation; D006133:Growth Substances / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D007375:Interleukin-1 / Q000494:pharmacology; D008297:Male; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins; D012867:Skin / Q000166:cytology; D012879:Skin Physiological Phenomena; D015533:Transcriptional Activation; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
C496453:FGF7 protein, human; D051526:Fibroblast Growth Factor 10; D006133:Growth Substances; D007375:Interleukin-1; D015335:Molecular Probes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D003907:Dexamethasone