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The Dynamic Interface of Viruses with STATs.

Viruses commonly antagonize the antiviral type I interferon response by targeting signal transducer and activator of transcription 1 (STAT1) and STAT2, key mediators of interferon signaling. Other STAT family members mediate signaling by diverse cytokines important to infection, but their relationship with viruses is more complex. Importantly, virus-STAT interaction can be antagonistic or stimulatory depending on diverse viral and cellular factors. While STAT antagonism can suppress immune pathways, many viruses promote activation of specific STATs to support viral gene expression and/or produ

Human hepatitis C virus NS5A protein alters intracellular calcium levels, induces oxidative stress, and activates STAT-3 and NF-kappa B.

The nonstructural protein 5A (NS5A) encoded by the human hepatitis C virus RNA genome is shown here to induce the activation of NF-kappaB and STAT-3 transcription factors from its cytoplasmic residence via oxidative stress. NS5A causes the disturbance of intracellular calcium. Ca2+ signaling triggers the elevation of reactive oxygen species in mitochondria, leading to the translocation of NF-kappaB and STAT-3 into the nucleus. Evidence is presented for the constitutive activation of STAT-3 by NS5A. In the presence of antioxidants [pyrrolidine dithiocarbamate (PDTC), N-acetyl l-cysteine (NAC)]

The role of a non-canonical JAK-STAT pathway in IFN therapy of poxvirus infection and multiple sclerosis: An example of Occam's Broom?

Signaling by cytokines such as the interferons (IFNs) involves Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) transcription factors. The beauty of the classical model of JAK-STAT signaling is its simplicity in that JAK-activated STATs in the nucleus are responsible for specific gene activation. The fact that many ligands, growth factors, and hormones use the same STAT transcription factors, but exert different functions at the level of the cell, tissue, and organ would suggest significant shortcomings in the classical model. Our studies have resulted in the de…

Placental malaria infection is associated with downregulation of STAT-6 and ANG-1 in decidual macrophages.

INTRODUCTION: Macrophages play a crucial immunological role in maintaining pregnancy. Placental malaria infection may cause dysfunction in decidual macrophages which then culminates in the associated pregnancy complications. Here, we determined the influence of placental malaria on decidual macrophages, by assessing their distribution based on their unique phenotypes, and examining their expression levels of transcription factors as well as angiogenic factors, in placentas from women living in a malaria-endemic area. METHODS: We compared these macrophage parameters in placentas from malaria i

Transcription factor profiling shows new ways towards new treatment options of cutaneous T cell lymphomas.

Most oncogenes encode activators of transcription factors or transcription factors themselves. Transcription factors that are induced by growth stimuli are, in contrast to transcription factors that regulate house keeping genes, tightly regulated and only active, when a stimulus (e.g. cytokines or other growth factors) is given. Examples of such transcription factors are members of the jun, fos, myc, NFkB and STAT gene families. In cancer cells this regulation is interrupted, resulting in constitutive activities of transcription factors that are normally silent. This in turn results in the inc

PP124. Trofoblastic invasion: The role of subunits STAT1 and STAT3.

INTRODUCTION: The trophoblastic migration/invasion are controlled by cytokines and growth factors that use intracellular pathways of signal to promote the regulation of gene expression, proliferation, cells differentiation, angiogenesis and embryonic development. The most important mediator of cytokine in trophoblastic invasion is the Janus-Kinase/signal transducer and activator of transcription (JAK/STAT). STATs are amino acids, compounds of 700-850 variable long-chain with isoforms α and β and molecular weight between 83-113kDa. The role of these factors in the pregnancy set up may contribut

Transcription factor STAT1 gene polymorphism is associated with the development of severe forms of periodontal disease.

INTRODUCTION: Periodontal disease (PD) is one of the most common inflammatory diseases, affecting about 10 % of the world population. The establishment of PD is influenced by polymorphisms in genes involved with the inflammatory response. Signal Transducer and Activator of Transcription (STAT)-1 is a transcription factor that plays a key role in the intracellular signaling triggered by cytokines and, thus, its activation is critical in inflammatory diseases. AIM AND METHODS: We aim to evaluate the occurrence of association between STAT-1 (rs3771300) polymorphism and distinct clinical forms an

Mast cell homeostasis and the JAK-STAT pathway.

The Janus kinase/signal transducer and activator of transcription (JAK-STAT) pathway mediates important responses in immune cells. Activation of any of the four JAK family members leads to phosphorylation of one or more of seven STAT family members. Phosphorylation of STAT family members leads to their dimerization and translocation into the nucleus, in which they bind specific DNA sequences to activate gene transcription. Regulation of JAKs and STATs therefore has a significant effect on signal transduction and subsequent cellular responses. Mast cells are important mediators of allergic dise

Duration of STAT5 activation influences the response of interleukin-2 receptor alpha gene to different cytokines.

Cytokines and growth factors regulate expression of their target genes via the Janus kinase (Jak)/signal transducers and activators of transcription (STAT) signaling pathway. One of the best characterized targets of STAT is the interleukin-2 receptor-alpha (IL-2Ralpha) gene. Its transcription is controlled by interleukin 2 (IL-2) through STAT5 activation. Using the PC60 cell line, in which the role of STAT5 in the regulation of the murine IL-2Ralpha gene by IL-2 has been elucidated, we have compared the response of this gene to IL-2, interleukin-9 (IL-9) and erythropoietin (Epo). IL-2 and IL-9

STAT3-mediated suppression of the pre-induction silencer Ets-2 in activated T helper cells.

BACKGROUND: Interleukin-2 (IL-2) is the first cytokine produced by naive T helper (Th) cells after antigen recognition and is essential for initiating Th cell proliferation and differentiation. We previously identified the transcription factor Ets-2 as a pre-induction silencer of IL-2, showing that its downregulation upon Th cell activation permits IL-2 transcription. However, the upstream mechanisms regulating Ets-2 expression remain undefined. Given the central role of STAT family transcription factors in Th cell gene regulation, we investigated whether STAT signaling controls Ets-2 transcri

The prognostic values of signal transducers activators of transcription family in ovarian cancer.

Signal transducer and activator of transcription (STAT), a family of latent cytoplasmic transcription factors, are composed of seven identified members (STAT1, STAT2, STAT3, STAT4, STAT5a, STAT5b, STAT6). STATs are associated with several biological processes such as cell proliferation, invasion, and metastasis in various cancer types. In addition, the STAT family has been well studied as a prognostic predictor for a considerable number of solid tumors. However, the prognostic value of the STAT family in ovarian cancer patients remains unclear. In our present study, we intend to access the pro

The downstream modulator of interferon-gamma, STAT1 is not genetically associated to the Dutch coeliac disease population.

Coeliac disease (CD) is a complex genetic disorder. Its etiology is owing to multiple genes and environmental factors, such as gluten. The first event in the pathogenesis of CD after the ingestion of gluten is the activation of a Th1 immune response that leads to villous atrophy. Although this immune response seems crucial to the disease's development, only the HLA-DQ2/DQ8 genes have been identified as causative immune genes related to CD. Recently, the activation of the transcription factor STAT1 and changes in its expression levels have confirmed the participation of the Janus kinase-signal

STAT Signaling in Metabolic Disorders: From Molecular Mechanisms to Therapeutic Implications.

Metabolic disorders such as obesity, type 2 diabetes, metabolic-associated steatotic liver disease, and cardiovascular complications arise from disrupted energy balance, chronic inflammation, and endocrine dysregulation. The signal transducer and activator of transcription (STAT) family functions as a central integrator of hormonal, cytokine, and metabolic cues, playing diverse tissue-specific and context-dependent roles. STAT3 regulates leptin and interleukin 6 signaling to control hypothalamic appetite circuits and maintain hepatic and adipose metabolic homeostasis. STAT5 promotes the activi

Janus kinase-targeting therapies in rheumatology: a mechanisms-based approach.

The four Janus kinase (JAK) proteins and seven signal transducer and activator of transcription (STAT) transcription factors mediate intracellular signal transduction downstream of cytokine receptors, which are implicated in the pathology of autoimmune, allergic and inflammatory diseases. Development of targeted small-molecule therapies such as JAK inhibitors, which have varied selective inhibitory profiles, has enabled a paradigm shift in the treatment of diverse disorders. JAK inhibitors suppress intracellular signalling mediated by multiple cytokines involved in the pathological processes o

Targeting the JAK/STAT pathway in solid tumors.

Aberrant activation of signal transducer and activator of transcription (STAT) proteins is associated with the development and progression of solid tumors. However, as transcription factors, these proteins are difficult to target directly. In this review, we summarize the role of targeting Janus kinases (JAKs), upstream activators of STATs, as a strategy for decreasing STAT activation in solid tumors. Preclinical studies in solid tumor cell line models show that JAK inhibitors decrease STAT activation, cell proliferation, and cell survival; in in vivo models, they also inhibit tumor growth. JA

Induction of differentiation by IL-6-type cytokines is impaired in myeloid leukaemia cells unable to activate Stat5a.

The block of differentiation in myeloid leukaemia can be overcome by treatment with a variety of agents including cytokines. Interleukin 6 (IL-6) and leukaemia inhibitory factor (LIF) induce macrophage differentiation and growth arrest through activation of the Janus kinase (Jak)/signal transducers and activators of transcription (Stat) signal pathway in murine M1 myeloid leukaemia cells. Treatment of various other myeloid leukaemia lines with LIF or IL-6 did not lead to induction of differentiation. Several defects in the cytokine triggered Jak/Stat signal pathway were striking in these lines

Evolving cognition of the JAK-STAT signaling pathway: autoimmune disorders and cancer.

The Janus kinase (JAK) signal transducer and activator of transcription (JAK-STAT) pathway is an evolutionarily conserved mechanism of transmembrane signal transduction that enables cells to communicate with the exterior environment. Various cytokines, interferons, growth factors, and other specific molecules activate JAK-STAT signaling to drive a series of physiological and pathological processes, including proliferation, metabolism, immune response, inflammation, and malignancy. Dysregulated JAK-STAT signaling and related genetic mutations are strongly associated with immune activation and c

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… STAT transcription factors in hematopoiesis and leukemogenesis: opportunities for therapeutic intervention. Leukemia. 2014;28:248–257. doi: 10.1038/leu.2013.192. 94. Zhang T, Kee WH, Seow KT, Fung W, Cao X. …

Psoriatic keratinocytes show reduced IRF-1 and STAT-1alpha activation in response to gamma-IFN.

Psoriasis is a chronic inflammatory dermatosis characterized by hyperproliferative keratinocytes (KC). The skin lesions are infiltrated by T cells, which secrete gamma interferon (gamma-IFN) and are believed to be necessary to maintain the psoriatic phenotype. In normal KC, gamma-IFN is a potent inhibitor of proliferation, but proliferation of KC persists in psoriatic plaques despite the presence of gamma-IFN. Immunostaining of interferon regulatory factor-1 (IRF-1) revealed that IRF-1 was localized to the basal cells of the epidermis in normal and in nonlesional psoriatic skin, but was suprab

Janus kinase/signal transducer and activator of transcription pathway in schizophrenia (Review).

Schizophrenia is a complex mental disorder that affects cognition, emotions and behaviour. Among the signaling pathways that show dysregulation in schizophrenia is the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. JAK/STAT is a pleiotropic pathway that plays key roles in multiple cellular functions. A brief overview of dysregulated signaling in schizophrenia is provided in the present review, focusing on the JAK/STAT pathway. Depending on the disease stage, dysregulation of signaling pathways causes inflammation, which is a key factor in the onset and mainte

JAK/STAT Signaling: Molecular Targets, Therapeutic Opportunities, and Limitations of Targeted Inhibitions in Solid Malignancies.

JAK/STAT signaling pathway is one of the important regulatory signaling cascades for the myriad of cellular processes initiated by various types of ligands such as growth factors, hormones, and cytokines. The physiological processes regulated by JAK/STAT signaling are immune regulation, cell proliferation, cell survival, apoptosis and hematopoiesis of myeloid and non-myeloid cells. Dysregulation of JAK/STAT signaling is reported in various immunological disorders, hematological and other solid malignancies through various oncogenic activation mutations in receptors, downstream mediators, and a