Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The expression of stromelysin, a major matrix metalloproteinase of connective tissues, is regulated by several cytokines, growth factors, protooncogenes as well as by 12-O-tetradecanoylphorbol-13-acetate (TPA). The human stromelysin gene promoter contains an activator protein-1 (Fos/Jun) binding site at -70, which is required for basal expression but is not necessary for the TPA response. In this study, using promoter deletion mutants in transient gene transfection experiments, we first identify the sequence from -220 to -202 as necessary for the TPA response of the stromelysin gene. Further, among the restriction fragments from the 1.3-kilobase long promoter, only the proximal fragment (-274 to -101) conferred a TPA response on the heterologous thymidine kinase gene promoter. The -220 to -202 sequence contains two copies of a motif similar to the polyomavirus enhancer A-binding protein-3 (PEA-3) site, which binds the Ets family of oncoproteins and transcription factors. Point mutations of either one of the two PEA-3 sites, in the 1.3-kilobase long stromelysin promoter context, reduced basal gene expression. However, only the mutation of the proximal, but not the distal PEA-3 site, significantly inhibited the TPA response. In cotransfection experiments, the Ets-2 protein transactivated the stromelysin promoter and the promoter proximal fragment containing the PEA-3 sites but not the promoters containing mutated PEA-3 sites. These data suggest that the PEA-3 site, but not the activator protein-1 site, and Ets-2 protein have a major role in the TPA induction of the human stromelysin gene transcription.
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PMID:A polyomavirus enhancer A-binding protein-3 site and Ets-2 protein have a major role in the 12-O-tetradecanoylphorbol-13-acetate response of the human stromelysin gene. 846 55

Collagenase, a prototypic matrix metalloproteinase, plays a major role in the degradation of the extracellular matrix. The essential amino acid L-tryptophan was recently shown to stimulate the expression of collagenase gene in human dermal fibroblast cultures. In this study, we focused our attention on the mechanisms responsible for activation of collagenase transcription by L-tryptophan. Incubation of fibroblasts with L-tryptophan resulted in a dose- and time-dependent elevation of collagenase and tissue inhibitor of metalloproteinase mRNA levels. The maximum enhancement in collagenae mRNA was approximately 50-fold. This effect was not abolished by cycloheximide, suggesting independence from ongoing protein synthesis. Transient cell transfections with a promoter/reporter gene construct containing 3.8 kb of 5' flanking DNA of the human collagenase gene linked to the chloramphenicol acetyl transferase (CAT) gene or a construct containing three phorbol ester-responsive AP-1 binding sequences (12-O-tetradecanoyl-phorbol-13-acetate-responsive element) in front of the thymidine kinase promoter linked to the CAT gene indicated enhancement of promoter activity by L-tryptophan. Furthermore, electrophoretic DNA mobility shift assays demonstrated enhanced DNA-protein complex formation specific for an AP-1 binding site probe with nuclear extracts prepared from cells incubated with L-tryptophan. These results collectively suggest that activation of collagenase gene expression in dermal fibroblasts by L-tryptophan is mediated through AP-1 binding elements in the collagenase gene promoter that are sufficient for gene response.
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PMID:L-tryptophan induces expression of collagenase gene in human fibroblasts: demonstration of enhanced AP-1 binding and AP-1 binding site-driven promoter activity. 886 82