Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.108 (TAT)
 2,389 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

B-1 F cells from mouse Leydig cell tumor (T 124958-R) were maintained in serum-free culture. Estrogen enhanced the growth of the cells, and this growth was suppressed by antiestrogens such as 4-hydroxytamoxifen or TAT, a newly developed antiestrogen. Since the growth of B-1 F cells was recently found to be inhibited by the metabolites of arachidonic acid, we examined the relationship between this metabolism and the enhancement of cell growth by estrogen. Among the modulators affecting the metabolism of arachidonic acid, 2-(12-hydroxydodeca-5,10-diynyl)-3,5,6-trimethyl-1,4-benzoqu inone, an inhibitor of 5-lipoxygenase, reproducibly stimulated the growth of the cells, whereas the cyclooxygenase inhibitor indomethacin had only the marginal growth-stimulatory effects. Phorbol ester had no growth-modulating effect. 17 beta-Estradiol and 2-(12-hydroxydodeca-5,10-diynyl)-3,5,6-trimethyl-1,4-benzoqu inone had some additive effects especially in terms of restoration of antiestrogen-induced inhibition. Moreover, the inhibition of DNA synthesis elicited by the addition of arachidonic acid in concentrations of 0.05 to 0.5 micrograms/ml was partly blocked by estrogen. Analyses of extracts of media and cells by high-pressure liquid chromatography and radioimmunoassay showed that 17 beta-estradiol inhibited the synthesis of leukotrienes B4, C4, D4, and E4 and this inhibition could be restored by antiestrogen. These results suggest that the enhancement of B-1 F cell growth by estrogen is at least partly mediated through its ability to inhibit leukotriene synthesis.
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PMID:Effects of estrogen on cell proliferation and leukotriene formation in transformed mouse Leydig cells cultured under serum-free conditions. 235 38

Tab2, originally described as a component of the inflammatory pathway, has been implicated in phenomena of gene de-repression in several contexts, due to its ability to interact with the NCoR corepressor. Tab2 interacts also with steroid receptors and dismisses NCoR from antagonist-bound Estrogen and Androgen Receptors on gene regulatory regions, thus modifying their transcriptional activity and leading to pharmacological resistance in breast and prostate cancer cells. We demonstrated previously that either Tab2 knock-down, or a peptide mimicking the Estrogen Receptor alpha domain interacting with Tab2, restore the antiproliferative response to Tamoxifen in Tamoxifen-resistant breast cancer cells. In this work, we map the domain of Tab2 responsible of Estrogen Receptor alpha interaction. First, using both co-immunoprecipitation and pull-down with recombinant proteins, we found that the central part of Tab2 is primarily responsible for this interaction, and that this region also interacts with Androgen Receptor. Then, we narrowed down the essential interaction region by means of competition assays using recombinant protein pull-down. The interaction motif was finally identified as a small region adjacent to, but not overlapping, the Tab2 MEKK1 phosphorylation sites. A synthetic peptide mimicking this motif efficiently displaced Tab2 from interacting with recombinant Estrogen Receptor alpha in vitro, prompting us to test its efficacy using derivatives of the MCF7 breast carcinoma cell lines that are spontaneously resistant to Tamoxifen. Indeed, we observed that this mimic peptide, made cell-permeable by addition of the TAT minimal carrier domain, reduced the growth of Tamoxifen-resistant MCF7 cells in the presence of Tamoxifen. These data indicate a novel functional domain of the Tab2 protein with potential application in drug design.
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PMID:A Novel Functional Domain of Tab2 Involved in the Interaction with Estrogen Receptor Alpha in Breast Cancer Cells. 2799 1