Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study examines endothelin-induced modulation of extracellular matrix synthesis and remodeling by fibroblasts, and its potential role in the pathogenesis of systemic sclerosis (scleroderma). Endothelin-1 promoted fibroblast synthesis of collagen types I and III, but not fibronectin, by a mechanism dependent upon both ETA and ETB receptors. Conversely, endothelin-1 inhibited both protein expression of matrix metalloproteinase 1 and zymographic activity exclusively via ETA receptors. A dual regulatory role for endothelin-1 in transcriptional regulation was suggested by the ability of endothelin-1 to enhance steady-state levels of collagen mRNA and activate the proalpha2(I) collagen (Col1a2) promoter, but in contrast to reduce matrix metalloproteinase 1 transcript expression and suppress transcription of a human matrix metalloproteinase 1 promoter reporter construct in transient transfection assays. Although endothelin-1 significantly enhanced remodeling of three-dimensional collagen lattices populated by normal fibroblasts, this was not observed for lattices populated by systemic sclerosis fibroblasts. Promotion of matrix remodeling was dependent upon ETA receptor expression and was blocked by specific inhibitors of tyrosine kinases or protein kinase C. Reverse transcriptase polymerase chain reaction, S1 nuclease, and functional cell surface binding studies showed that normal and systemic sclerosis fibroblasts express both ETA and ETB receptors (predominantly ETA), but that ETA receptor mRNA levels and ETA binding sites on fibroblasts cultured from systemic sclerosis skin biopsies are reduced by almost 50%. Endothelin-1 is thus able to induce a fibrogenic phenotype in normal fibroblasts that is similar to that of lesional systemic sclerosis fibroblasts. Moreover, reduced responsiveness to exogenous endothelin-1 in systemic sclerosis suggests that downstream pathways may have already been activated in vivo. These data further implicate dysregulated endothelin-receptor pathways in fibroblasts in the pathogenesis of connective tissue fibrosis.
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PMID:Fibroblast matrix gene expression and connective tissue remodeling: role of endothelin-1. 1123 16

Systemic sclerosis is a connective tissue disease characterized by excessive deposition of extracellular matrix in the skin as well as various internal organs. Cellular infiltrates are found in the dermis in early systemic sclerosis, which are suggested to play an important part. Recent studies suggest the involvement of monocyte chemoattractant protein-1, a C-C chemokine, in the fibrotic process. This study examines the role of monocyte chemoattractant protein-1 in the induction of dermal sclerosis in a murine model of bleomycin-induced scleroderma. Immunohistochemical analysis showed that expression of monocyte chemoattractant protein-1 in the infiltrating mononuclear cells was enhanced at 2 to 3 wk following bleomycin treatment, whereas expression of monocyte chemoattractant protein-1 in fibroblasts was detected at later stages in the sclerotic skin. Reverse transcriptase-polymerase chain reaction analysis showed that monocyte chemoattractant protein-1 mRNA expression in the lesional skin peaked at 2 to 3 wk following bleomycin treatment. Expression of CCR-2, a major receptor for monocyte chemo-attractant protein-1, was also upregulated in the lesional skin at both protein and mRNA levels following bleomycin treatment. Administration of anti-monocyte chemoattractant protein-1 neutralizing antibody together with local bleomycin treatment reduced dermal sclerosis, along with a decrease of collagen content in the skin as well as mRNA expression of type I collagen. In vitro analysis showed that stimulation with monocyte chemoattractant protein-1 (10 ng per mL) upregulated alpha1(I) collagen and decorin mRNA expression in normal dermal fibroblasts, whereas mRNA levels of fibronectin and biglycan were not altered. These data suggest that monocyte chemoattractant protein-1 and CCR-2 signaling plays an important part in the pathogenesis of bleomycin-induced scleroderma. Monocyte chemoattractant protein-1 may contribute to the induction of dermal sclerosis via its direct effect of upregulation of mRNA expression of extracellular matrix on fibroblasts, as well as indirect effect mediated by a number of cytokines released from immunocytes recruited into the lesional skin.
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PMID:Role of monocyte chemoattractant protein-1 and its receptor,CCR-2, in the pathogenesis of bleomycin-induced scleroderma. 1292 9

Systemic sclerosis (SSc) is a connective tissue disorder characterized by excessive deposition of extracellular matrix in the affected skin as well as various internal organs, vascular injury and immune abnormality; however, the etiology of SSc remains still unknown. We previously established an experimental mouse model for scleroderma by repeated local injections of bleomycin, a DNA damaging agent. In this study, we examined the induction of apoptosis and the expression of p53, p21 (Waf1/Cip1), and proliferating cell nuclear antigen (PCNA) in the lesional skin following bleomycin exposure in this model. Dermal sclerosis was induced by alternate day's injections of bleomycin for 4 weeks. TUNEL assay showed that apoptotic cells began to appear at 1 week after bleomycin exposure, and were prominently detected at 3-4 weeks. Immunohistochemical examination showed increased expression of p53 and p21 mainly in the infiltrating mononuclear cells at 2 weeks after bleomycin treatment. Bleomycin treatment markedly enhanced PCNA expression at 1-2 weeks, mainly in mesenchyme, as compared with control phosphate buffered saline treatment. Reverse transcriptase-polymerase chain reaction analysis showed that the expression of p53 and p21 mRNA was concurrently upregulated at 1-2 weeks after bleomycin treatment. Taken together, coordinate increased levels of p53 and p21 preceded the maximal induction of apoptosis and dermal sclerosis. Our findings suggest that apoptotic processes are involved in the pathophysiology of bleomycin-induced scleroderma, which may be mediated, in part, by the upregulation of p53 and p21.
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PMID:Increased expression of p53 and p21 (Waf1/Cip1) in the lesional skin of bleomycin-induced scleroderma. 1580 28