Browsing by Subject "STAT3 transcription factor"

Now showing 1 - 5 of 5
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    CD45 Phosphatase Inhibits STAT3 Transcription Factor Activity in Myeloid Cells and Promotes Tumor-Associated Macrophage Differentiation
    (Elsevier, 2016-02-16) Kumar, Vinit; Cheng, Pingyan; Condamine, Thomas; Mony, Sridevi; Languino, Lucia R.; McCaffrey, Judith C.; Hockstein, Neil; Guarino, Michael; Masters, Gregory; Penman, Emily; Denstman, Fred; Xu, Xiaowei; Altieri, Dario C.; Du, Hong; Yan, Cong; Gabrilovich, Dmitry I.; Department of Pathology and Laboratory Medicine, IU School of Medicine
    Recruitment of monocytic myeloid-derived suppressor cells (MDSCs) and differentiation of tumor-associated macrophages (TAMs) are the major factors contributing to tumor progression and metastasis. We demonstrated that differentiation of TAMs in tumor site from monocytic precursors was controlled by downregulation of the activity of the transcription factor STAT3. Decreased STAT3 activity was caused by hypoxia and affected all myeloid cells but was not observed in tumor cells. Upregulation of CD45 tyrosine phosphatase activity in MDSCs exposed to hypoxia in tumor site was responsible for downregulation of STAT3. This effect was mediated by the disruption of CD45 protein dimerization regulated by sialic acid. Thus, STAT3 has a unique function in the tumor environment in controlling the differentiation of MDSC into TAM, and its regulatory pathway could be a potential target for therapy.
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    Critical Roles of STAT3 in β-Adrenergic Functions in the Heart
    (American Heart Association, 2016-01-05) Zhang, Wenjun; Qu, Xiuxia; Chen, Biyi; Snyder, Marylynn; Wang, Meijing; Li, Baiyan; Tang, Yue; Chen, Hanying; Zhu, Wuqiang; Zhan, Li; Yin, Ni; Li, Deqiang; Li, Xie; Liu, Ying; Zhang, J. Jillian; Fu, Xin-Yuan; Rubart, Michael; Song, Long-Sheng; Huang, Xin-Yun; Shou, Weinian; Department of Pediatrics, IU School of Medicine
    BACKGROUND: β-Adrenergic receptors (βARs) play paradoxical roles in the heart. On one hand, βARs augment cardiac performance to fulfill the physiological demands, but on the other hand, prolonged activations of βARs exert deleterious effects that result in heart failure. The signal transducer and activator of transcription 3 (STAT3) plays a dynamic role in integrating multiple cytokine signaling pathways in a number of tissues. Altered activation of STAT3 has been observed in failing hearts in both human patients and animal models. Our objective is to determine the potential regulatory roles of STAT3 in cardiac βAR-mediated signaling and function. METHODS AND RESULTS: We observed that STAT3 can be directly activated in cardiomyocytes by β-adrenergic agonists. To follow up this finding, we analyzed βAR function in cardiomyocyte-restricted STAT3 knockouts and discovered that the conditional loss of STAT3 in cardiomyocytes markedly reduced the cardiac contractile response to acute βAR stimulation, and caused disengagement of calcium coupling and muscle contraction. Under chronic β-adrenergic stimulation, Stat3cKO hearts exhibited pronounced cardiomyocyte hypertrophy, cell death, and subsequent cardiac fibrosis. Biochemical and genetic data supported that Gαs and Src kinases are required for βAR-mediated activation of STAT3. Finally, we demonstrated that STAT3 transcriptionally regulates several key components of βAR pathway, including β1AR, protein kinase A, and T-type Ca(2+) channels. CONCLUSIONS: Our data demonstrate for the first time that STAT3 has a fundamental role in βAR signaling and functions in the heart. STAT3 serves as a critical transcriptional regulator for βAR-mediated cardiac stress adaption, pathological remodeling, and heart failure.
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    Exploring transcriptional regulators Ref-1 and STAT3 as therapeutic targets in malignant peripheral nerve sheath tumours
    (Springer Nature, 2021) Gampala, Silpa; Shah, Fenil; Zhang, Chi; Rhodes, Steven D.; Babb, Olivia; Grimard, Michelle; Wireman, Randall S.; Rad, Ellie; Calver, Brian; Bai, Ren-Yuan; Staedtke, Verena; Hulsey, Emily L.; Saadatzadeh, M. Reza; Pollok, Karen E.; Tong, Yan; Smith, Abbi E.; Clapp, D. Wade; Tee, Andrew R.; Kelley, Mark R.; Fishel, Melissa L.; Pediatrics, School of Medicine
    Background: MPNST is a rare soft-tissue sarcoma that can arise from patients with NF1. Existing chemotherapeutic and targeted agents have been unsuccessful in MPNST treatment, and recent findings implicate STAT3 and HIF1-α in driving MPNST. The DNA-binding and transcriptional activity of both STAT3 and HIF1-α is regulated by Redox factor-1 (Ref-1) redox function. A first-generation Ref-1 inhibitor, APX3330, is being tested in cancer clinical trials and could be applied to MPNST. Methods: We characterised Ref-1 and p-STAT3 expression in various MPNST models. Tumour growth, as well as biomarkers of apoptosis and signalling pathways, were measured by qPCR and western blot following treatment with inhibitors of Ref-1 or STAT3. Results: MPNSTs from Nf1-Arfflox/floxPostnCre mice exhibit significantly increased positivity of p-STAT3 and Ref-1 expression when malignant transformation occurs. Inhibition of Ref-1 or STAT3 impairs MPNST growth in vitro and in vivo and induces apoptosis. Genes highly expressed in MPNST patients are downregulated following inhibition of Ref-1 or STAT3. Several biomarkers downstream of Ref-1 or STAT3 were also downregulated following Ref-1 or STAT3 inhibition. Conclusions: Our findings implicate a unique therapeutic approach to target important MPNST signalling nodes in sarcomas using new first-in-class small molecules for potential translation to the clinic.
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    Stat3 Is Important for Follicular Regulatory T Cell Differentiation
    (Plos, 2016-05-05) Wu, Hao; Xie, Markus M.; Liu, Hong; Dent, Alexander; Department of Microbiology & Immunology, IU School of Medicine
    The production of antibody is precisely controlled during the germinal center (GC) reaction. This process is dependent on the help from follicular T helper (Tfh) cells to germinal center (GC) B cells and is regulated by regulatory follicular T helper (Tfr) cells. How Tfr cells develop and how their suppressive activity functions are not well understood. Here, we found that Stat3 is indispensible for Tfr cell differentiation. After immunization with Sheep Red Blood Cells (SRBC), the loss of Tfr cells caused by deletion of Stat3 in Treg cells does not affect the size of Tfh or GC B cell population, but rather leads to strongly enhanced production of antigen-specific IgG1 and IgG2b. In Peyer's patches (PPs) in the gut, we found that Stat3 expression in Treg cells is also required for Tfr cell formation to commensal organisms. However, loss of Tfr cells in the gut did not affect the numbers of Tfh cells and GC B cells, nor affect IgG1 or IgA switching by GC B cells. Overall, our study has uncovered unique roles of Stat3 in Tfr cell differentiation and the regulation of the antibody response.
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    STAT5 represses a STAT3-independent Th17-like program during Th9 cell differentiation
    (The American Association of Immunologists, 2021) Canaria, D. Alejandro; Yan, Bingyu; Clare, Maia G.; Zhang, Zonghao; Taylor, Grace A.; Boone, David L.; Kazemian, Majid; Olson, Matthew R.; Microbiology and Immunology, School of Medicine
    IL-9-producing Th cells, termed Th9 cells, contribute to immunity against parasites and cancers but have detrimental roles in allergic disease and colitis. Th9 cells differentiate in response to IL-4 and TGF-β, but these signals are insufficient to drive Th9 differentiation in the absence of IL-2. IL-2-induced STAT5 activation is required for chromatin accessibility within Il9 enhancer and promoter regions and directly transactivates the Il9 locus. STAT5 also suppresses gene expression during Th9 cell development, but these roles are less well defined. In this study, we demonstrate that human allergy-associated Th9 cells exhibited a signature of STAT5-mediated gene repression that is associated with the silencing of a Th17-like transcriptional signature. In murine Th9 cell differentiation, blockade of IL-2/STAT5 signaling induced the expression of IL-17 and the Th17-associated transcription factor Rorγt. However, IL-2-deprived Th9 cells did not exhibit a significant Th17- or STAT3-associated transcriptional signature. Consistent with these observations, differentiation of IL-17-producing cells under these conditions was STAT3-independent but did require Rorγt and BATF. Furthermore, ectopic expression of Rorγt and BATF partially rescued IL-17 production in STAT3-deficient Th17 cells, highlighting the importance of these factors in this process. Although STAT3 was not required for the differentiation of IL-17-producing cells under IL-2-deprived Th9 conditions, their prolonged survival was STAT3-dependent, potentially explaining why STAT3-independent IL-17 production is not commonly observed in vivo. Together, our data suggest that IL-2/STAT5 signaling plays an important role in controlling the balance of a Th9 versus a Th17-like differentiation program in vitro and in allergic disease.