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)

Interleukin-6 (IL-6) is the major cytokine inducing transcription of human C-reactive protein (CRP) during the acute phase response. STAT (signal transducers and activators of transcription) family members, recently shown to be important mediators of the effects of many cytokines including IL-6, generally induce their effects by binding to palindromic sequences with TT(N)5AA motifs. We report an IL-6 responsive element in the proximal region of the human CRP 5'-flanking region that bears a TT(N)4AA motif, which we have termed CRP acute phase response element (CRP-APRE). In Hep3B cells, IL-6 but not interferon-gamma was capable of activating CAT constructs driven by the CRP promoter containing CRP-APRE. Overexpressed STAT3 was able to transactivate CRP-chloramphenicol acetyltransferase constructs through the CRP-APRE and was able to enhance endogenous CRP mRNA accumulation in response to IL-6. STAT3 (or an antigenically related molecule) bound to the CRP-APRE in response to IL-6. Overexpression of STAT3 in the presence of IL-6 was capable of inducing expression of a construct consisting of the CRP-APRE and a minimal thymidine kinase promoter lacking a C/EBP site. Taken together, these findings indicate that STAT3 participates in the transcriptional activation of CRP in response to IL-6.
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PMID:STAT3 participates in transcriptional activation of the C-reactive protein gene by interleukin-6. 862 22

Interferon-gamma (IFNgamma) and tumor necrosis factor-alpha (TNFalpha) cooperate to induce the expression of many gene products during inflammation. The present report demonstrates that a portion of this cooperativity is mediated by synergism between two distinct transcription factors: signal transducer and activator of transcription 1 (STAT1) and nuclear factor kappaB (NF-kappaB). IFNgamma and TNFalpha synergistically induce expression of mRNAs encoding interferon regulatory factor-1 (IRF-1), intercellular adhesion molecule-1, Mig (monokine induced by gamma-interferon), and RANTES (regulated on activation normal T cell expressed and secreted) in normal but not STAT1-deficient mouse fibroblasts, indicating a requirement for STAT1. Transient transfection assays in fibroblasts using site-directed mutants of a 1.3-kilobase pair sequence of the IRF-1 gene promoter revealed that the synergy was dependent upon two sequence elements; a STAT binding element and a kappaB motif. Artificial constructs containing a single copy of both a STAT binding element and a kappaB motif linked to the herpes virus thymidine kinase promoter were able to mediate synergistic response to IFNgamma and TNFalpha; such response varied with both the relative spacing and the specific sequence of the regions between these two sites. Cooperatively responsive sequence constructs bound both STAT1alpha and NF-kappaB in nuclear extracts prepared from IFNgamma- and/or TNFalpha-stimulated fibroblasts, although binding of individual factors was not cooperative. Thus, the frequently observed synergy between IFNgamma and TNFalpha in promoting inflammatory response depends in part upon cooperation between STAT1alpha and NF-kappaB, which is most likely mediated by their independent interaction with one or more components of the basal transcription complex.
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PMID:Synergy between interferon-gamma and tumor necrosis factor-alpha in transcriptional activation is mediated by cooperation between signal transducer and activator of transcription 1 and nuclear factor kappaB. 916 60

Glycoprotein 130 (gp130), a shared component of all the receptors for the interleukin-6 cytokine family, transduces cytokine signals in part by activating latent cytoplasmic signal transducers and activators of transcription (STATs). STATs subsequently translocate into the nucleus and stimulate gene expression. In the studies reported here, the 5'-flanking region of the human gp130 gene was isolated and the transcription initiation sites were mapped. To demonstrate that the isolated DNA fragment contained a functional promoter, a plasmid construct containing 2433 base pairs of the gp130 5'-flanking region, inserted upstream from the firefly luciferase gene, was transiently transfected into HepG2 hepatoma cells. The construct exhibited constitutive promoter activity. In addition, a 5-h treatment with interleukin-6 or oncostatin M stimulated the activity of this promoter severalfold. Localization of the cytokine response element by 5'-deletion analysis and site-directed mutagenesis revealed a cis-acting binding site for activated STAT complexes. Furthermore, DNA binding analysis demonstrated that this element binds activated STAT1 and STAT3 homo- and heterodimers. This STAT-binding element was sufficient to confer cytokine stimulation to a minimal herpesvirus thymidine kinase promoter. These results establish that the DNA fragment we have isolated contains the human gp130 promoter and that interleukin-6 type cytokines may influence the activity of this promoter via activated STATs.
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PMID:Isolation and characterization of the human gp130 promoter. Regulation by STATS. 916 75

STAT transcription factors are induced by a number of growth factors and cytokines. Within minutes of induction, the STAT proteins are phosphorylated on tyrosine and serine residues and translocated to the nucleus, where they bind to their DNA targets. The leukemia inhibitory factor (LIF) mediates pleiotropic and sometimes opposite effects both in vivo and in cultured cells. It is known, for example, to prevent differentiation of embryonic stem (ES) cells in vitro. To get insights into LIF-regulated signaling in ES cells, we have analyzed protein-binding and transcriptional properties of STAT recognition sites in ES cells cultivated in the presence and in the absence of LIF. We have detected a specific LIF-regulated DNA-binding activity implicating the STAT3 protein. We show that STAT3 phosphorylation is essential for this LIF-dependent DNA-binding activity. The possibility that ERK2 or a closely related protein kinase, whose activity is modulated in a LIF-dependent manner, contributes to this phosphorylation is discussed. Finally, we show that the multimerized STAT3-binding DNA element confers LIF responsiveness to a minimal thymidine kinase promoter. This, together with our observation that overexpression of STAT3 dominant-negative mutants abrogates this LIF responsiveness, clearly indicates that STAT3 is involved in LIF-regulated transcriptional events in ES cells. Finally, stable expression of such a dominant negative mutant of STAT3 induces morphological differentiation of ES cells despite continuous LIF supply. Our results suggest that STAT3 is a critical target of the LIF signaling pathway, which maintains pluripotent cell proliferation.
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PMID:Leukemia inhibitory factor-dependent transcriptional activation in embryonic stem cells. 929 77

GH and PRL stimulate insulin production in pancreatic beta-cells through induction of insulin gene transcription. The transcriptional effects of GH are mediated through the binding of signal transducer and activator of transcription-5 (STAT5) to a consensus recognition sequence (TTCnnnGAA) in the rat insulin-1 promoter. In this study we demonstrate that PRL also induces the binding of STAT5 proteins to the rat insulin-1 STAT5 motif. However, the magnitude of binding of STAT5 nuclear proteins, as assessed by electrophoretic mobility shift assays, was only 1/30th that of the binding of the same STAT5 proteins to the beta-casein STAT5 site. The differences in the affinities of the rat insulin-1 and beta-casein STAT5 motifs are explained in part by differences in promoter sequences flanking the STAT5 sites. To assess the importance of the STAT motif in PRL induction of insulin gene transcription, we deleted the STAT5 consensus sequence in the rat insulin 1 promoter, cloned the truncated promoter upstream of the luciferase reporter gene, and transfected the construct into rat insulinoma (INS-1) cells. The transcriptional activity of this construct was compared with that of the wild-type promoter. Although deletion of the STAT5 site in the promoter reduced the basal luciferase activity, the response to PRL was unaffected. PRL also induced transcription of constructs containing the wild-type human insulin promoter or the rat insulin-2 promoter, which contain no classic STAT5 sequences. The transcriptional effect of PRL was manifest even when cells were incubated in glucose-free medium, indicating that the action of the hormone is not mediated solely through changes in glucose uptake or glucose metabolism. To identify PRL-responsive regions of the rat and human insulin promoters, we constructed a series of promoter truncations and assessed their responsiveness to PRL. A PRL-responsive region of the rat insulin-1 promoter was localized between nucleotides -165 and -109. A PRL-responsive region of the human insulin promoter was localized between nucleotides -346 and -250. Additional regions of the human and rat insulin-1 promoters were required for PRL induction of a heterologous, minimal thymidine kinase promoter, suggesting that there are multiple PRL-responsive elements in the insulin genes. These observations suggest a glucose- and STAT5-independent pathway by which PRL may induce insulin gene transcription.
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PMID:Prolactin induction of insulin gene transcription: roles of glucose and signal transducer and activator of transcription 5. 1141 99

Previously, we reported that a recombinant vaccinia virus (VACV) carrying a light-emitting fusion gene enters, replicates in, and reveals the locations of tumors in mice. A new recombinant VACV, GLV-1h68, as a simultaneous diagnostic and therapeutic agent, was constructed by inserting three expression cassettes (encoding Renilla luciferase-Aequorea green fluorescent protein fusion, beta-galactosidase, and beta-glucuronidase) into the F14.5L, J2R (encoding thymidine kinase) and A56R (encoding hemagglutinin) loci of the viral genome, respectively. I.v. injections of GLV-1h68 (1x10(7) plaque-forming unit per mouse) into nude mice with established (approximately 300-500 mm3) s.c. GI-101A human breast tumors were used to evaluate its toxicity, tumor targeting specificity, and oncolytic efficacy. GLV-1h68 showed an enhanced tumor targeting specificity and much reduced toxicity compared with its parental LIVP strains. The tumors colonized by GLV-1h68 exhibited growth, inhibition, and regression phases followed by tumor eradication within 130 days in 95% of the mice tested. Tumor regression in live animals was monitored in real time based on decreasing light emission, hence demonstrating the concept of a combined oncolytic virus-mediated tumor diagnosis and therapy system. Transcriptional profiling of regressing tumors based on a mouse-specific platform revealed gene expression signatures consistent with immune defense activation, inclusive of IFN-stimulated genes (STAT-1 and IRF-7), cytokines, chemokines, and innate immune effector function. These findings suggest that immune activation may combine with viral oncolysis to induce tumor eradication in this model, providing a novel perspective for the design of oncolytic viral therapies for human cancers.
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PMID:Eradication of solid human breast tumors in nude mice with an intravenously injected light-emitting oncolytic vaccinia virus. 1794 38

Surfactant protein C (SPC), a key component of pulmonary surfactant, also plays a role in regulating inflammation. SPC deficiency in patients and mouse models is associated with increased inflammation and delayed repair, but the key drivers of SPC-regulated inflammation in response to injury are largely unknown. This study focuses on a new mechanism of SPC as an anti-inflammatory molecule using SPC-TK/SPC-KO (surfactant protein C-thymidine kinase/surfactant protein C knockout) mice, which represent a novel sterile injury model that mimics clinical acute respiratory distress syndrome (ARDS). SPC-TK mice express the inducible suicide gene thymidine kinase from by the SPC promoter, which targets alveolar type 2 (AT2) cells for depletion in response to ganciclovir (GCV). We compared GCV-induced injury and repair in SPC-TK mice that have normal endogenous SPC expression with SPC-TK/SPC-KO mice lacking SPC expression. In contrast to SPC-TK mice, SPC-TK/SPC-KO mice treated with GCV exhibited more severe inflammation, resulting in over 90% mortality; there was only 8% mortality of SPC-TK animals. SPC-TK/SPC-KO mice had highly elevated inflammatory cytokines and granulocyte infiltration in the bronchoalveolar lavage (BAL) fluid. Consistent with a proinflammatory phenotype, immunofluorescence revealed increased phosphorylated signal transduction and activation of transcription 3 (pSTAT3), suggesting enhanced Janus kinase (JAK)/STAT activation in inflammatory and AT2 cells of SPC-TK/SPC-KO mice. The level of suppressor of cytokine signaling 3, an anti-inflammatory mediator that decreases pSTAT3 signaling, was significantly decreased in the BAL fluid of SPC-TK/SPC-KO mice. Hyperactivation of pSTAT3 and inflammation were rescued by AZD1480, a JAK1/2 inhibitor. Our findings showing a novel role for SPC in regulating inflammation via JAK/STAT may have clinical applications.
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PMID:Surfactant protein C dampens inflammation by decreasing JAK/STAT activation during lung repair. 2934 96