The Experts below are selected from a list of 314994 Experts worldwide ranked by ideXlab platform
Bernd Groner - One of the best experts on this subject based on the ideXlab platform.
-
the coactivator of transcription creb binding protein interacts preferentially with the glycosylated form of stat5
Journal of Biological Chemistry, 2004Co-Authors: Christina Gewinner, Christian Beisenherzhuss, Natasha E Zachara, Gerald W Hart, Robert N Cole, Bernd GronerAbstract:The signal transducer and activator of transcription (Stat) gene family comprises seven members with similarities in their domain structure and a common mode of activation. Members of this gene family mediate interferon induction of gene transcription and the response to a large number of growth factors and hormones. Extracellular ligand binding to transmembrane receptors causes the intracellular activation of associated tyrosine kinases, phosphorylation of Stat molecules, dimerization, and translocation to the nucleus. Prolactin-induced phosphorylation of Stat5 is a key event in the development and differentiation of mammary epithelial cells. In addition to the crucial phosphorylation at tyrosine 694, we have identified an O-linked N-acetylglucosamine (O-GlcNAc) as another secondary modification essential for the transcriptional induction by Stat5. This modification was only found on nuclear Stat5 after cytokine activation. Similar observations were made with Stat1, Stat3, and STAT6. Glycosylation of Stat5, however, does not seem to be a prerequisite for nuclear translocation. Mass spectrometric analysis revealed a glycosylated peptide in the N-terminal region of Stat5. Replacement of threonine 92 by an alanine residue (Stat5a-T92A) strongly reduced the prolactin induction of Stat5a glycosylation and abolished transactivation of a target gene promoter. Only the glycosylated form of Stat5 was able to bind the coactivator of transcription CBP, an essential interaction for Stat5-mediated gene transcription.
-
the coactivator of transcription creb binding protein interacts preferentially with the glycosylated form of stat5
Journal of Biological Chemistry, 2004Co-Authors: Christina Gewinner, Christian Beisenherzhuss, Natasha E Zachara, Gerald W Hart, Robert N Cole, Bernd GronerAbstract:The signal transducer and activator of transcription (Stat) gene family comprises seven members with similarities in their domain structure and a common mode of activation. Members of this gene family mediate interferon induction of gene transcription and the response to a large number of growth factors and hormones. Extracellular ligand binding to transmembrane receptors causes the intracellular activation of associated tyrosine kinases, phosphorylation of Stat molecules, dimerization, and translocation to the nucleus. Prolactin-induced phosphorylation of Stat5 is a key event in the development and differentiation of mammary epithelial cells. In addition to the crucial phosphorylation at tyrosine 694, we have identified an O-linked N-acetylglucosamine (O-GlcNAc) as another secondary modification essential for the transcriptional induction by Stat5. This modification was only found on nuclear Stat5 after cytokine activation. Similar observations were made with Stat1, Stat3, and STAT6. Glycosylation of Stat5, however, does not seem to be a prerequisite for nuclear translocation. Mass spectrometric analysis revealed a glycosylated peptide in the N-terminal region of Stat5. Replacement of threonine 92 by an alanine residue (Stat5a-T92A) strongly reduced the prolactin induction of Stat5a glycosylation and abolished transactivation of a target gene promoter. Only the glycosylated form of Stat5 was able to bind the coactivator of transcription CBP, an essential interaction for Stat5-mediated gene transcription.
-
p300/CBP is required for transcriptional induction by interleukin-4 and interacts with STAT6
Nucleic acids research, 1999Co-Authors: Sebastien Gingras, Bernd Groner, Jacques Simard, Edith PfitznerAbstract:Interleukin-4 (IL-4) induces tyrosine phosphorylation of the latent transcription factor STAT6, which mediates the transcriptional responses of IL-4. The transactivation domain of STAT6 has recently been mapped to the C-terminal region of STAT6. We have investigated the mechanism by which STAT6, through its transactivation domain, induces transcription. Previous studies have shown that diverse regulated transcription factors interact with coactivators such as p300 and CBP. We report that STAT6 used the interaction with p300/CBP to exert its stimulatory effects. Overexpression of p300/CBP increased IL-4-induced transcription of STAT6 activated reporter genes. The requirement of p300/CBP for STAT6-mediated transactivation is shown by coexpression of the adenovirus E1A protein. E1A repressed the IL-4-induced reporter gene activity, while mutants of E1A, which do not interact with p300/CBP, failed to block the IL-4-induced response. In addition, we found that the minimal transactivation domain of STAT6, when fused to the GAL4 DNA-binding domain, was repressed by E1A, whereas the fusion protein p300-VP16 increased the transcriptional activity. In two-hybrid protein interaction assays in mammalian cells, we mapped the interaction domain of CBP to a C-terminal region between amino acids 1850 and 2176, a region distinct from the interaction domain of CBP with Stat1, Stat2 or Stat5. Finally, we show that antibodies raised against p300 coimmunoprecipitated STAT6 and p300 from transfected COS7 cells and antibodies against STAT6 coimmunprecipitated endogenous STAT6 and CBP from Ba/F3 cells. Our data suggest that the transactivation domain of STAT6 makes contact with the basal transcription machinery by binding to p300/CBP.
-
IL-10 induces DNA binding activity of three STAT proteins (Stat1, Stat3, and Stat5) and their distinct combinatorial assembly in the promoters of selected genes
FEBS Letters, 1996Co-Authors: Jens Wehinger, Fabrice Gouilleux, Bernd Groner, Juergen Finke, Roland Mertelsmann, R Weber-nordt, Renate Maria Weber-nordtAbstract:Interaction of IL-10 with its receptor leads to the activation of STAT transcription factors. Herein we report the IL-10 dependent simultaneous activation of three STAT transcription factors: Stat1, Stat3, and Stat5. Upon IL-10 treatment multiple Stat proteins become simultaneously activated, and bind to different promoters with equal kinetics but form distinct homo- and heterodimeric transcriptionally active complexes depending on the STAT-consensus elements of a selected gene promoter. Upon IL-10 treatment Stat1, 3, and 5 bind to the GRR of the FcgammaRI gene, activated Stat1 and 3 bind to the SIE sequence of the c-fos promoter and transcriptionally active Stat5 assembles at the PRL-STAT consensus sequence of the beta-casein gene. Thus, functionally relevant STAT dimerization is influenced by the activated cytokine receptor as well as the specific STAT consensus sequence present in a specific gene promoter.
Lijia Wang - One of the best experts on this subject based on the ideXlab platform.
-
investigation of the interaction between creb binding protein and stat4 STAT6
Molecular Biology Reports, 2011Co-Authors: Mingxiang Zhang, Daiyin Tian, Enmei Liu, Jihong Dai, Lijia WangAbstract:Coactivator CBP (CREB-binding protein) has been implicated in the regulation of transcription for all signal transducer and activator of transcription factors (STATs); however, the mechanism remains unclear. Using yeast two-hybrid screening and immunoprecipitation techniques, we investigated the direct interaction of CBP with STAT4 and STAT6. The full-length CBP and five fragments of CBP (residues 1–436, 529–1200, 1–697, 967–1574 and 1678–2175) were constructed using pGBKT7 vectors, while STAT4, STAT6 and N-terminal deleted STAT4 were constructed using pGADT7 vectors. It was found that STAT4, but not STAT6, interacted directly with the 1678–2175 fragment of CBP containing the ZZ, TAZ2 and SID domain. The N-terminal of STAT4 plays an important role in this interaction since N-terminal deleted STAT4 failed to bind to any CBP fragment. The results were confirmed by immunoprecipitation using HA-tagged STAT4 or STAT6 and c-Myc tagged CBP. This work will contribute to our understanding of the mechanisms of Th cytokine imbalance.
-
Investigation of the interaction between CREB-binding protein and STAT4/STAT6.
Molecular biology reports, 2010Co-Authors: Mingxiang Zhang, Daiyin Tian, Enmei Liu, Jihong Dai, Lijia WangAbstract:Coactivator CBP (CREB-binding protein) has been implicated in the regulation of transcription for all signal transducer and activator of transcription factors (STATs); however, the mechanism remains unclear. Using yeast two-hybrid screening and immunoprecipitation techniques, we investigated the direct interaction of CBP with STAT4 and STAT6. The full-length CBP and five fragments of CBP (residues 1–436, 529–1200, 1–697, 967–1574 and 1678–2175) were constructed using pGBKT7 vectors, while STAT4, STAT6 and N-terminal deleted STAT4 were constructed using pGADT7 vectors. It was found that STAT4, but not STAT6, interacted directly with the 1678–2175 fragment of CBP containing the ZZ, TAZ2 and SID domain. The N-terminal of STAT4 plays an important role in this interaction since N-terminal deleted STAT4 failed to bind to any CBP fragment. The results were confirmed by immunoprecipitation using HA-tagged STAT4 or STAT6 and c-Myc tagged CBP. This work will contribute to our understanding of the mechanisms of Th cytokine imbalance.
Michael David - One of the best experts on this subject based on the ideXlab platform.
-
Identification of a Nuclear Stat1 Protein Tyrosine Phosphatase
Molecular and cellular biology, 2002Co-Authors: Johanna Ten Hoeve, Michael David, Maria De Jesus Ibarra-sanchez, Wei Zhu, Michel L. Tremblay, Ke ShuaiAbstract:Upon interferon (IFN) stimulation, Stat1 becomes tyrosine phosphorylated and translocates into the nucleus, where it binds to DNA to activate transcription. The activity of Stat1 is dependent on tyrosine phosphorylation, and its inactivation in the nucleus is accomplished by a previously unknown protein tyrosine phosphatase (PTP). We have now purified a Stat1 PTP activity from HeLa cell nuclear extract and identified it as TC45, the nuclear isoform of the T-cell PTP (TC-PTP). TC45 can dephosphorylate Stat1 both in vitro and in vivo. Nuclear extracts lacking TC45 fail to dephosphorylate Stat1. Furthermore, the dephosphorylation of IFN-induced tyrosine-phosphorylated Stat1 is defective in TC-PTP-null mouse embryonic fibroblasts (MEFs) and primary thymocytes. Reconstitution of TC-PTP-null MEFs with TC45, but not the endoplasmic reticulum (ER)-associated isoform TC48, rescues the defect in Stat1 dephosphorylation. The dephosphorylation of Stat3, but not Stat5 or STAT6, is also affected in TC-PTP-null cells. Our results identify TC45 as a PTP responsible for the dephosphorylation of Stat1 in the nucleus.
-
Regulation of STAT protein synthesis by c-Cbl
Oncogene, 2001Co-Authors: Warren A Blesofsky, Kerri Mowen, Robert M Arduini, Darren P Baker, Maria A Murphy, David D L Bowtell, Michael DavidAbstract:Many cytokines and growth factors induce transcription of immediate early response genes by activating members of the Signal Transducers and Activators of Transcription (STAT) family. Although significant progress has been made in understanding the events that lead to the activation of STAT proteins, less is known about the regulation of their expression. Here we report that murine embryonic fibroblasts derived from c-Cbl-deficient mice display significantly increased levels of STAT1 and STAT5 protein. In contrast, STAT2 and STAT3 expression, as well as the levels of the tyrosine kinases Jak1 and Tyk2, appear to be regulated independently of c-Cbl. Interestingly, the half-life of STAT1 was unaffected by the presence of c-Cbl, indicating that c-Cbl acts independently of STAT1 degradation. Further analysis revealed similar levels of STAT1 mRNA, however, a dramatically increased rate of STAT1 protein synthesis was observed in c-Cbl-deficient cells. Thus, our findings demonstrate an additional control mechanism over STAT1 function, and also provide a novel biological effect of the Cbl protein family.
-
distinct mechanisms of stat phosphorylation via the interferon α β receptor selective inhibition of stat3 and stat5 by piceatannol
Journal of Biological Chemistry, 2000Co-Authors: Michael DavidAbstract:Interferon-alpha (IFNalpha) can activate several members of the signal transducers and activator of transcription (STAT) transcription factor family, a process that requires the tyrosine kinases Jak1 and Tyk2. Here we provide evidence that IFNalpha-mediated activation of various STAT proteins is regulated by distinct mechanisms. Piceatannol, previously reported as a Syk/ZAP70-specific kinase inhibitor, selectively inhibits the tyrosine phosphorylation of STAT3 and STAT5, but not of STAT1 and STAT2. This inhibition is paralleled by the loss of Jak1 and IFNAR1 tyrosine phosphorylation in response to IFNalpha, whereas Tyk2 and IFNAR2 tyrosine phosphorylation is unaffected. Last, the IFNalpha-induced serine phosphorylation of STAT1 and STAT3 is not inhibited by piceatannol but is sensitive to the Src kinase-specific inhibitor PP2. Thus, our results not only demonstrate that the IFNalpha/beta receptor utilizes distinct mechanisms to trigger the tyrosine phosphorylation of specific STAT proteins, but they also indicate a diverging pathway that leads to the serine phosphorylation of STAT1 and STAT3.
Kenneth M. Murphy - One of the best experts on this subject based on the ideXlab platform.
-
Role of the Stat4 N domain in receptor proximal tyrosine phosphorylation.
Molecular and cellular biology, 2000Co-Authors: Theresa L. Murphy, E. D. Geissal, J. D. Farrar, Kenneth M. MurphyAbstract:The STAT (signal transducers and activators of transcription) family of transcription factors reside as latent cytoplasmic monomers which are phosphorylated on a conserved tyrosine residue in response to ligand-induced receptor activation (5, 15, 38). Following tyrosine phosphorylation, STAT proteins undergo homo- and heterodimerization via reciprocal interactions involving their conserved SH2 domains, followed by STAT dimer nuclear translocation and participation in transcriptional regulation of various cytokine responsive genes. STAT dimers bind the palindromic gamma interferon (IFN-γ)-activated sequence (GAS) TTCNmGAA, where m equals 3 for all STAT proteins except STAT6 (6, 7, 14, 19). STAT-specific binding site preferences have been identified involving both the central nucleotide core and sequences flanking the core palindrome (10, 25, 33, 34). Furthermore, higher-order interactions between STAT dimers, in which a tetrameric complex of two STAT dimers cooperatively binds two adjacent GAS elements, have been described for Stat1, Stat4, and Stat5 (42, 43, 47). It has been suggested that such tetramer formation is facilitated through interactions between the highly conserved N-terminal domain (N domain), facilitating STAT dimer binding to low-affinity, nonconsensus STAT binding sites (47). Other functions for the N domain have also been suggested, including roles in nuclear localization and binding to CREB-binding protein, or p300 (39, 48). The specificity of STAT activation by cytokines is in part mediated by the selective interaction of their SH2 domains with distinct tyrosine-containing motifs located within the cytoplasmic domains of specific cytokine receptors. In addition, each STAT protein has private physiologic functions exerted presumably by selective activation of distinct target genes. One important STAT-dependent biologic function involves T helper differentiation. In particular, Stat4 activation plays a significant role in directing development of T helper type 1 (Th1) T cells from naive CD4+ precursors (16, 18, 41). Control of Th1 differentiation is exerted both by the tissue-restricted expression of Stat4 and by the limited activation of Stat4 by only certain cytokines. Stat4 is activated by interleukin 12 (IL-12) (1, 16), a cytokine which potently induces Th1 development (13, 22) through recruitment to a tyrosine-based motif in the IL-12 receptor β2 (IL-12Rβ2) subunit via the Stat4 SH2 domain (26). IL-12 activates Stat4 in all species examined, and the requirement for Stat4 in Th1 development has been confirmed by targeted deletion of Stat4 in mice (18, 41). IFN-α also activates Stat4 and induces Th1 development in human T cells (1, 32), but not mouse T cells (32, 46). Stat4 activation by IFN-α, however, does not involve direct binding to the cytoplasmic domain of the IFN-α receptor (IFN-αR), but instead occurs through an intermediate step (8). First, IFN-α signaling leads to phosphorylation of a conserved tyrosine in the receptor cytoplasmic domain that acts to recruit Stat2, which is subsequently phosphorylated on a conserved tyrosine 690. Stat2 serves as an adapter that binds the SH2 domains of both Stat1 and Stat4. Stat1 binds to tyrosine 690 of Stat2; however, Stat4 binds to a distinct region of Stat2, specifically to the most carboxy-terminal regions of Stat2. In summary, IL-12 and IFN-α each induce Th1 development and activate Stat4, but the Stat4 SH2 domain interaction differs between these receptor pathways. How Stat4 promotes Th1 development is unclear. Stat4 could directly regulate activity of the IFN-γ gene. Recombinant Stat4 produces a footprint on specific sites within the IFN-γ gene promoter and first intron, sites which are low affinity and nonconsensus. The cooperative interaction of adjacent sites with Stat4 dimers binding as a tetramer via adjacent amino termini was suggested as a mechanism for augmenting IFN-γ gene expression (47), although the requirement for these sites in regulation of the native IFN-γ gene has not been established. Alternately, Stat4 may regulate expression of other signaling molecules or transcription factors that act in Th1 development. For example, Stat4 is required for the Th1-specific expression of the Ets transcription family member ERM (28), although a role for ERM in IFN-γ gene expression has not been demonstrated. In addressing potential Stat4 tetramer interactions for IFN-γ regulation, we became interested in the role of the Stat4 N domain in mediating STAT dimer-dimer interactions. The structure of the STAT N domain was determined from the isolated N domain from Stat4, which was found to naturally pack as a dimer in the crystal (43). In the Stat4 N domain, composed of eight alpha helices which form a hook-like structure, a conserved tryptophan residue, W37, was shown to be engaged in critical internal polar interactions between interacting helices of reciprocal N domain subunits (43). For functional analysis, the role of this tryptophan was evaluated in Stat1 rather than Stat4; however, mutation of this tryptophan prevented tetramer formation of recombinant Stat1 protein and caused the loss of an IFN-γ augmentation of a synthetic promoter composed of multimerized GAS elements. Furthermore, mutation of this conserved tryptophan in Stat5 was recently shown to prevent the ability of Stat5 to undergo tetramer formation on the adjacent STAT sites present in the IL-2Rα chain promoter (17). So far, the role of this tryptophan-mediated N domain dimerization had not been evaluated for Stat4 nor evaluated in a system where native physiologic responses to Stat4 activation could be observed. To this end, we have carried out a mutational analysis of the Stat4 N domain for IFN-α- and IL-12-induced Stat4 activation using cell lines that lack Stat4 expression and primary T cells derived from Stat4-deficient mice. Surprisingly, our results point to additional roles of the Stat4 N domain beyond mediating tetramer formation on DNA. Our results indicate that the Stat4 N domain also can influence the ability of STAT proteins to undergo successful interactions with cytokine receptor complexes. Importantly, the W37A mutation within the N domain of Stat4 interferes with IFN-α-induced tyrosine phosphorylation of the Stat4 monomer, interrupting Stat4 activation before formation of the Stat4 dimer. This result precludes any conclusions regarding functional tetramer activity based on this mutation for Stat4. Finally, the data suggest that N-domains may be involved in targeting certain STATs to receptors, influencing their suitability as substrates for receptor-dependent kinases.
-
Recruitment of Stat4 to the Human Interferon-α/β Receptor Requires Activated Stat2
The Journal of biological chemistry, 2000Co-Authors: J. David Farrar, Theresa L. Murphy, Janice D. Smith, Kenneth M. MurphyAbstract:Abstract Stat4 activation is involved in differentiation of type 1 helper (Th1) T cells. Although Stat4 is activated by interleukin (IL)-12 in both human and murine T cells, Stat4 is activated by interferon (IFN)-α only in human, but not murine, CD4+ T cells. This species-specific difference in cytokine activation of Stat4 underlies critical differences in Th1 development in response to cytokines and is important to the interpretation of murine models of immunopathogenesis. Here, we sought to determine the mechanism of Stat4 recruitment and activation by the human IFN-α receptor. Analysis of phosphopeptide binding analysis suggests that Stat4 does not interact directly with tyrosine-phosphorylated amino acid residues within the cytoplasmic domains of either of the subunits of the IFN-α receptor complex. Expression of murine Stat4 in the Stat1-deficient U3A and the Stat2-deficient U6A cell lines shows that IFN-α-induced Stat4 phosphorylation requires the presence of activated Stat2 but not Stat1. Thus, in contrast to the direct recruitment of Stat4 by the IL-12 receptor, Stat4 activation by the human IFN-α receptor occurs through indirect recruitment by intermediates involving Stat2.
-
recruitment of stat4 to the human interferon α β receptor requires activated stat2
Journal of Biological Chemistry, 2000Co-Authors: David J Farrar, Theresa L. Murphy, Janice D. Smith, Kenneth M. MurphyAbstract:Abstract Stat4 activation is involved in differentiation of type 1 helper (Th1) T cells. Although Stat4 is activated by interleukin (IL)-12 in both human and murine T cells, Stat4 is activated by interferon (IFN)-α only in human, but not murine, CD4+ T cells. This species-specific difference in cytokine activation of Stat4 underlies critical differences in Th1 development in response to cytokines and is important to the interpretation of murine models of immunopathogenesis. Here, we sought to determine the mechanism of Stat4 recruitment and activation by the human IFN-α receptor. Analysis of phosphopeptide binding analysis suggests that Stat4 does not interact directly with tyrosine-phosphorylated amino acid residues within the cytoplasmic domains of either of the subunits of the IFN-α receptor complex. Expression of murine Stat4 in the Stat1-deficient U3A and the Stat2-deficient U6A cell lines shows that IFN-α-induced Stat4 phosphorylation requires the presence of activated Stat2 but not Stat1. Thus, in contrast to the direct recruitment of Stat4 by the IL-12 receptor, Stat4 activation by the human IFN-α receptor occurs through indirect recruitment by intermediates involving Stat2.
Mingxiang Zhang - One of the best experts on this subject based on the ideXlab platform.
-
investigation of the interaction between creb binding protein and stat4 STAT6
Molecular Biology Reports, 2011Co-Authors: Mingxiang Zhang, Daiyin Tian, Enmei Liu, Jihong Dai, Lijia WangAbstract:Coactivator CBP (CREB-binding protein) has been implicated in the regulation of transcription for all signal transducer and activator of transcription factors (STATs); however, the mechanism remains unclear. Using yeast two-hybrid screening and immunoprecipitation techniques, we investigated the direct interaction of CBP with STAT4 and STAT6. The full-length CBP and five fragments of CBP (residues 1–436, 529–1200, 1–697, 967–1574 and 1678–2175) were constructed using pGBKT7 vectors, while STAT4, STAT6 and N-terminal deleted STAT4 were constructed using pGADT7 vectors. It was found that STAT4, but not STAT6, interacted directly with the 1678–2175 fragment of CBP containing the ZZ, TAZ2 and SID domain. The N-terminal of STAT4 plays an important role in this interaction since N-terminal deleted STAT4 failed to bind to any CBP fragment. The results were confirmed by immunoprecipitation using HA-tagged STAT4 or STAT6 and c-Myc tagged CBP. This work will contribute to our understanding of the mechanisms of Th cytokine imbalance.
-
Investigation of the interaction between CREB-binding protein and STAT4/STAT6.
Molecular biology reports, 2010Co-Authors: Mingxiang Zhang, Daiyin Tian, Enmei Liu, Jihong Dai, Lijia WangAbstract:Coactivator CBP (CREB-binding protein) has been implicated in the regulation of transcription for all signal transducer and activator of transcription factors (STATs); however, the mechanism remains unclear. Using yeast two-hybrid screening and immunoprecipitation techniques, we investigated the direct interaction of CBP with STAT4 and STAT6. The full-length CBP and five fragments of CBP (residues 1–436, 529–1200, 1–697, 967–1574 and 1678–2175) were constructed using pGBKT7 vectors, while STAT4, STAT6 and N-terminal deleted STAT4 were constructed using pGADT7 vectors. It was found that STAT4, but not STAT6, interacted directly with the 1678–2175 fragment of CBP containing the ZZ, TAZ2 and SID domain. The N-terminal of STAT4 plays an important role in this interaction since N-terminal deleted STAT4 failed to bind to any CBP fragment. The results were confirmed by immunoprecipitation using HA-tagged STAT4 or STAT6 and c-Myc tagged CBP. This work will contribute to our understanding of the mechanisms of Th cytokine imbalance.
