title: Constitutive activation of the collagenase promoter in recessive dystrophic epidermolysis bullosa fibroblasts: role of endogenously activated AP-1.
abstract: Recessive dystrophic epidermolysis bullosa (RDEB) is a mutilating disease of the skin characterized by recurrent blistering and erosions that result from compromised integrity of the basement membrane zone. In this study, fibroblasts derived from the skin of RDEB patients were characterized for expression of the major metalloproteinases, particularly interstitial collagenase. Consistent with previous reports on increased collagenase protein levels in fibroblasts from some RDEB patients, we found that steady-state levels of collagenase mRNA were significantly increased in fibroblast strains derived from three of five RDEB patients compared to fibroblasts obtained from normal donors. Stromelysin mRNA was elevated in the same three fibroblast strains, whereas expression of neither the 72- nor the 92-kDa type IV collagenases was different from that of controls. Tissue inhibitor of metalloproteinases was expressed in RDEB fibroblasts at levels similar to those observed in normal fibroblasts. To investigate the mechanism behind the steady-state elevation in collagenase and stromelysin expression, AP-1 expression and activation were studied. Although levels of Jun expression were not different from those seen in normal fibroblasts, AP-1 activity, as assessed by ability to bind to a TPA response element-containing oligonucleotide, was endogenously elevated in RDEB fibroblasts compared to normal fibroblasts. Transfection studies using a plasmid construct containing the collagenase promoter linked to a CAT reporter gene demonstrated that RDEB fibroblasts were able to support active transcription of the promoter compared to normal fibroblasts. These studies support the hypothesis that RDEB fibroblasts contain chronically activated AP-1, and perhaps other transactivating factors, that contribute to the cellular phenotype of collagenase and stromelysin overexpression.
authors.affiliation: Department of Dermatology, Stanford University Medical Center, California 94305.
authors.forename: E N
authors.initials: EN
authors.lastname: Unemori
authors.forename: C
authors.initials: C
authors.lastname: Mauch
authors.forename: W
authors.initials: W
authors.lastname: Hoeffler
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.forename: E P
authors.initials: EP
authors.lastname: Amento
authors.forename: E A
authors.initials: EA
authors.lastname: Bauer
mesh_terms: D002478:Cells, Cultured; D017364:Collagenases / Q000235:genetics* / Q000378:metabolism; D016108:Epidermolysis Bullosa Dystrophica / Q000209:etiology / Q000235:genetics* / Q000378:metabolism*; D005786:Gene Expression Regulation; D005808:Genes, Recessive; D006801:Humans; D019278:Matrix Metalloproteinase 3; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D017364:Collagenases; D008666:Metalloendopeptidases; D019278:Matrix Metalloproteinase 3