Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The interleukin-7 (IL-7) receptor is expressed throughout T-cell differentiation and, although lacking a tyrosine kinase domain, mediates tyrosine phosphorylation in T cells. We have identified IL-7-induced activation of three cyoplasmic tyrosine kinases in T cells, Jak1, Jak3, and the src-like kinase p56lck. Many members of the cytokine receptor superfamily activate the Jak protein tyrosine kinase family, with resultant phosphorylation of the Stat transcriptional activator factors. We describe here a novel function of the Jak kinases, because Jak kinase activity is not only required for Stat activation but also for P13 kinase response to IL-7 in human T cells. We show that IL-7 receptor-mediated Jak activation can occur independently of p56lck activity. IL-7-induced P13 kinase activation, mediated by tyrosine phosphorylation of the P13 kinase p85 subunit, is essential to the IL-7 proliferative signal and also occurs in the absence of src family kinase activity. Jak3 is found associated with the p85 subunit of P13 kinase in an IL-7-responsive manner in T cells and appears to regulate IL-7-induced P13 kinase activation by mediating tyrosine phosphorylation of the p85 subunit. Specific inhibition of IL-7-induced Jak kinase activity ablates p85 tyrosine phosphorylation, subsequent P13 kinase activation, and, ultimately, proliferation. The ability to regulate P13 kinase activity indicates a more generalized role for the Jak family than activation of gene transcription via the Stat family in cytokine receptor signal transduction.
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PMID:JAK3 protein tyrosine kinase mediates interleukin-7-induced activation of phosphatidylinositol-3' kinase. 766 55

Treatment of T47-D human breast carcinoma cells with recombinant prolactin (rhPRL) induced a concentration- and time-dependent increase in the phosphotyrosine content of JAK2. rhPRL also stimulated JAK2 tyrosine phosphorylation more weakly in three other breast carcinoma lines, MCF-7, ZR-75-1 and MDA-MB-231. Furthermore it stimulated tyrosine phosphorylation of two isoforms of the transcriptional activator STAT5, STAT5a and STAT5b. Surprisingly, rhPRL treatment of T47-D cells also stimulated tyrosine phosphorylation of focal adhesion kinase (FAK), as determined by immunoprecipitation with anti-phosphotyrosine antibody followed by immunoblotting with a specific FAK antibody. The effect of rhPRL was rapid and concentration-dependent, being maximal at 5 ng/ml. At rhPRL concentrations above 25 ng/ml, FAK tyrosine phosphorylation declined but remained above control levels at 100 ng/ml. rhPRL also stimulated paxillin tyrosine phosphorylation in T47-D cells with similar concentration- and time-dependence. In a second human breast carcinoma cell line, MCF-7, rhPRL produced very similar effects on FAK and paxillin tyrosine phosphorylation. These findings identify a new protein tyrosine kinase pathway in the action of the lactogenic hormone rhPRL and represent the first report that a hormone acting through a member of the haemopoietin receptor superfamily can regulate the FAK/paxillin pathway.
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PMID:Prolactin stimulates the JAK2 and focal adhesion kinase pathways in human breast carcinoma T47-D cells. 916 61

Genistein, a natural flavone found in soy has been postulated to be responsible for lowering the rate of breast cancer in Asian women. Our previous studies have shown that genistein exerts multiple suppressive effects on both estrogen receptor positive (ER+) as well as estrogen receptor negative (ER-) human breast carcinoma lines suggesting that the mechanisms of these effects may be independent of ER pathways. In the present study however we provide evidence that in the ER+ MCF-7, T47D and 549 lines but not in the ER-MDA-MB-231 and MDA-MB-468 lines both presumed "ER-dependent" and "ER-independent" actions of genistein are mediated through ER pathways. Genistein's antiproliferative effects are estrogen dependent in these ER+ lines, being more pronounced in estrogen-containing media and in the presence of exogenous 17-beta estradiol. Genistein also inhibits the expression of ER-downstream genes including pS2 and TGF-beta in these ER+ lines and this inhibition is also dependent on the presence of estrogen. Genistein inhibits estrogen-induced protein tyrosine kinase (PTK) activity. Genistein is only a weak transcriptional activator and actually decreases ERE-CAT levels induced by 17-beta estradiol in the ER+ lines. Genistein also decreases steady state ER mRNA only in the presence of estrogen in the ER+ lines thereby manifesting another suppression of and through the ER pathway. Our observations resurrect the hypothesis that genistein functions as a "good estrogen" in ER+ breast carcinomas. Since chemopreventive effects of genistein would be targeted to normal ER-positive ductal-lobular cells of the breast, this "good estrogen" action of genistein is most relevant to our understanding of chemoprevention.
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PMID:Genistein's "ER-dependent and independent" actions are mediated through ER pathways in ER-positive breast carcinoma cell lines. 1095 3

Src is a nonreceptor protein tyrosine kinase that is expressed widely throughout the central nervous system and is involved in diverse biological functions. Mice homozygous for a spontaneous mutation in Src (Src (thl/thl) ) exhibited hypersociability and hyperactivity along with impairments in visuospatial, amygdala-dependent, and motor learning as well as an increased startle response to loud tones. The phenotype of Src (thl/thl) mice showed significant overlap with Williams-Beuren syndrome (WBS), a disorder caused by the deletion of several genes, including General Transcription Factor 2-I (GTF2I). Src phosphorylation regulates the movement of GTF2I protein (TFII-I) between the nucleus, where it is a transcriptional activator, and the cytoplasm, where it regulates trafficking of transient receptor potential cation channel, subfamily C, member 3 (TRPC3) subunits to the plasma membrane. Here, we demonstrate altered cellular localization of both TFII-I and TRPC3 in the Src mutants, suggesting that disruption of Src can phenocopy behavioral phenotypes observed in WBS through its regulation of TFII-I.
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PMID:Disruption of Src Is Associated with Phenotypes Related to Williams-Beuren Syndrome and Altered Cellular Localization of TFII-I 2646 74