TNIK regulation of interferon signaling and endothelial cell response to virus infection

Background

Traf2 and Nck-interacting kinase (TNIK) is known for its regulatory role in various processes within cancer cells. However, its role within endothelial cells (ECs) has remained relatively unexplored.

Methods

Leveraging RNA-seq data and Ingenuity Pathway Analysis (IPA), we probed the potential impact of TNIK depletion on ECs.

Results

Examination of RNA-seq data uncovered more than 450 Differentially Expressed Genes (DEGs) in TNIK-depleted ECs, displaying a fold change exceeding 2 with a false discovery rate (FDR) below 0.05. IPA analysis unveiled that TNIK depletion leads to the inhibition of the interferon (IFN) pathway [-log (p-value) >11], downregulation of IFN-related genes, and inhibition of Hypercytokinemia/Hyperchemokinemia [-log (p-value) >8]. The validation process encompassed qRT-PCR to evaluate mRNA expression of crucial IFN-related genes, immunoblotting to gauge STAT1 and STAT2 protein levels, and ELISA for the quantification of IFN and cytokine secretion in siTNIK-depleted ECs. These assessments consistently revealed substantial reductions upon TNIK depletion. When transducing HUVECs with replication incompetent E1-E4 deleted adenovirus expressing green fluorescent protein (Ad-GFP), it was demonstrated that TNIK depletion did not affect the uptake of Ad-GFP. Nonetheless, TNIK depletion induced cytopathic effects (CPE) in ECs transduced with wild-type human adenovirus serotype 5 (Ad-WT).

Summary

Our findings suggest that TNIK plays a crucial role in regulating the EC response to virus infections through modulation of the IFN pathway.

Interplay between signal transducers and activators of transcription (STAT) proteins and cancer: involvement, therapeutic and prognostic perspective

Signal transducers and activators of transcription or STAT are proteins that consist of various transcription factors that are responsible for activating genes regarding cell proliferation, differentiation, and apoptosis. They commonly activate several cytokine, growth, or hormone factors via the JAK-STAT signaling pathway by tyrosine phosphorylation which are responsible for giving rise to numerous immune responses. Mutations within the Janus-Kinases (JAKs) or the STATs can set off the commencement of various malfunctions of the immune system of the body; carcinogenesis being an inevitable outcome. STATs are known to act as both oncogenes and tumor suppressor genes which makes it a hot topic of investigation. Various STATs related mechanisms are currently being investigated to analyze its potential of serving as a therapeutic base for numerous immune diseases and cancer; a deeper understanding of the molecular mechanisms involved in the signaling pathways can contribute to the same. This review will throw light upon each STAT member in causing cancer malignancies by affecting subsequent signaling pathways and its genetic and epigenetic associations as well as various inhibitors that could be used to target these pathways thereby devising new treatment options. The review will also focus upon the therapeutic advances made in cancers that most commonly affect people and discuss how STAT genes are identified as prognostic markers.

The Th17/IL-17 Axis and Host Defense Against Fungal Infections

Chronic mucocutaneous candidiasis (CMC) was recognized as a primary immunodeficiency in the early 1970s. However, for almost 40 years, its genetic etiology remained unknown. The progressive molecular and cellular description of inborn errors of immunity (IEI) with syndromic CMC pointed toward a possible role of IL-17-mediated immunity in protecting against fungal infection and CMC. Since 2011, novel IEI affecting either the response to or production of IL-17A and/or IL-17F (IL-17A/F) in patients with isolated or syndromic CMC provided formal proof of the pivotal role of the IL-17 axis in mucocutaneous immunity to Candida spp, and, to a lesser extent, to Staphylococcus aureus in humans. In contrast, IL-17-mediated immunity seems largely redundant against other common microbes in humans. In this review, we outline the current knowledge of IEI associated with impaired IL-17A/F-mediated immunity, highlighting our current understanding of the role of IL-17A/F in human immunity.

Citrus alkaline extracts improve LPS-induced pulmonary fibrosis via epithelial mesenchymal transition signals

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a serious life threatening clinical critical illness. ARDS-related pulmonary fibrosis is a common complication of ARDS. The occurrence of early pulmonary fibrosis indicates a higher incidence and mortality of multiple organ failure. LPS-induced ARDS-related pulmonary fibrosis model in mice was established in this study. And we have explored the anti-pulmonary fibrosis effects and molecular mechanisms of the Citrus Alkaline Extracts (CAE) in vivo and in vitro.

METHODS

Pulmonary fibrosis mouse model and lung epithelial cell injury model were established in this study. H&E, Masson and Sirius Red staining were used to estimate lung tissue damage. Immunohistochemistry and western blotting were used to analyze proteins expression. Protein-protein interaction was observed by Co-Immunoprecipitation. Systemic impact of CAE on signaling pathway was examined by RNA-seq.

RESULTS

Through H&E, Masson and Sirius Red staining, it was convincingly indicated that therapeutic administration of CAE alleviated lung injury and fibrosis, while pretreated administration of CAE showed weak improvement. In vitro experiments showed that CAE had dual regulation to E-cadherin and N-cadherin, the important indicators of epithelial-mesenchymal transition (EMT). And it was further demonstrated that CAE reversed TGF-β1-induced EMT mainly through Wnt/β-catenin, Stat3/6 and COX2/PGE2 signals. Through RNA-Seq, we discovered important mechanisms by which CAE exerts its therapeutic effect. And network pharmacology analysis demonstrated core potential targets of CAE in EMT.

CONCLUSION

Thus, this study provides new therapeutic effects of CAE in anti-fibrosis, and offers potential mechanisms for CAE in LPS-induced pulmonary fibrosis.

Macrophage xCT deficiency drives immune activation and boosts responses to immune checkpoint blockade in lung cancer

Tumor-associated macrophages (TAMs) play an important role in remodeling the tumor microenvironment (TME), which promotes tumor growth, immunosuppression and angiogenesis. Because of the high plasticity of macrophages and the extremely complex tumor microenvironment, the mechanism of TAMs in cancer progression is still largely unknown. In this study, we found that xCT (SLC7A11) was overexpressed in lung cancer-associated macrophages. Higher xCT in TAMs was associated with poor prognosis and was an independent predictive factor in lung cancer. In addition, lung cancer growth and progression was inhibited in xCT knockout mice, especially macrophage-specific xCT knockout mice. We also found that the deletion of macrophage xCT inhibited AKT/STAT6 signaling activation and reduced M2-type polarization of TAMs. Macrophage xCT deletion recruited more CD8⁺ T cells and activated the lung cancer cell-mediated and IFN-γ-induced JAK/STAT1 axis and increased the expression of its target genes, including CXCL10 and CD274. The combination of macrophage xCT deletion and anti-PDL1 antibody achieved better tumor inhibition. Finally, combining the xCT inhibitor erastin with an anti-PDL1 antibody was more potent in inhibiting lung cancer progression. Therefore, suppression of xCT may overcome resistance to cancer immunotherapy.

Metformin may induce immunologic tolerance at the maternal-foetal interface in early human pregnancy

OBJECTIVE

Repeated pregnancy loss has been shown to be related to decidual immune imbalance. Metformin has been found to promote a shift in the Th17/Treg balance towards immune tolerance. Our research aims to evaluate and obtain further information on the role and potential mechanism of metformin on Th17/Treg balance in the early pregnancy decidua.

METHODS

Decidual immune cells from normal pregnancy women were treated with metformin, pro-inflammatory cytokines or metformin + cytokines respectively. The mRNA expression levels of STAT3, STAT5, RORC and Foxp3 were detected by qRT-PCR. The proportions of Th17 and Treg cells, the stability of Treg cells, and the STATs phosphorylation levels of T cells were evaluated by flow cytometry. The cytokine concentrations in the culture medium were detected by ELISA.

RESULTS

After treated with metformin, indicators related to immune tolerance, including the mRNA expression and phosphorylation levels of STAT5, mRNA expression level of Foxp3, the proportion of Treg cell, and the IL-10 concentration increased significantly. Indicators related to immune rejection including the mRNA expression level of STAT3, the proportion of Th17 cell, and the IL-17A concentration showed a significant decrease. In inflammatory conditions, the proportion of Th-like Treg cells increased. Metformin promoted CD25 expression to maintain Treg cell stability.

CONCLUSION

Metformin has beneficial effects on immunological tolerance at the maternal-foetal interface in early pregnancy. The underlying mechanism may be that metformin restores the Th17/Treg balance by changing the expression of STATs, which is conducive to establishing maternal-foetal immune tolerance.

Exportin-1 is critical for cell proliferation and survival in adult T cell leukemia

Since treatment options for adult T cell leukemia (ATL) associated with human T cell leukemia virus type 1 (HTLV-1) fail to obtain long-term response, novel therapies targeting ATL-dysregulated pathways are necessary. Dysregulated nuclear import and export machinery is common in malignancies. This study aimed to investigate the potential of exportin-1 (XPO1), which mediates nuclear export of cargos, as a target in ATL. RT-PCR and western blotting were performed to determine XPO1 expression. We evaluated XPO1's effects on cell proliferation and viability through WST-8 assays, cell cycle and apoptosis via Hoechst 33342 staining and flow cytometry, and intracellular signaling cascades using western blotting. XPO1 expression was upregulated in HTLV-1-infected T cells. XPO1 knockdown reduced cell proliferation. XPO1 inhibitor KPT-330 also reduced proliferation, increased DNA damage, and induced G1 cell cycle arrest and caspase-dependent apoptosis. KPT-330 downregulated cell cycle regulators (CDK2/4/6, cyclin D2, c-Myc and phosphorylated pRb) and anti-apoptotic proteins (XIAP, c-IAP1/2, survivin and Mcl-1), and upregulated p53, p21 and Bak. KPT-330 suppressed XPO1 and increased the nuclear localization of cargos (NF-κB RelA and its negative regulator IκBα, protein phosphatase 2A and its inhibitor SET, p53 and its negative regulator MDM2, p21, p27, FOXO1 and pRb). KPT-330 treatment resulted in the abrogation of aberrant pathways (NF-κB, Akt and STAT3/5) simultaneously through the activation of tumor suppressor proteins and inhibition of oncogenes and proliferative/survival factors. These findings encourage investigating the use of KPT-330 in clinical trials targeting ATL.

Peptides Regulating Proliferative Activity and Inflammatory Pathways in the Monocyte/Macrophage THP-1 Cell Line

This study evaluates the effects of five different peptides, the Epitalon^® tetrapeptide, the Vilon^® dipeptide, the Thymogen^® dipeptide, the Thymalin^® peptide complex, and the Chonluten^® tripeptide, as regulators of inflammatory and proliferative processes in the human monocytic THP-1, which is a human leukemia monocytic cell line capable of differentiating into macrophages by PMA in vitro. These peptides (Khavinson Peptides^®), characterized by Prof. Khavinson from 1973 onwards, were initially isolated from animal tissues and found to be organ specific. We tested the capacity of the five peptides to influence cell cultures in vitro by incubating THP-1 cells with peptides at certain concentrations known for being effective on recipient cells in culture. We found that all five peptides can modulate key proliferative patterns, increasing tyrosine phosphorylation of mitogen-activated cytoplasmic kinases. In addition, the Chonluten tripeptide, derived from bronchial epithelial cells, inhibited in vitro tumor necrosis factor (TNF) production of monocytes exposed to pro-inflammatory bacterial lipopolysaccharide (LPS). The low TNF release by monocytes is linked to a documented mechanism of TNF tolerance, promoting attenuation of inflammatory action. Therefore, all peptides inhibited the expression of TNF and pro-inflammatory IL-6 cytokine stimulated by LPS on terminally differentiated THP-1 cells. Lastly, by incubating the THP1 cells, treated with the peptides, on a layer of activated endothelial cells (HUVECs activated by LPS), we observed a reduction in cell adhesion, a typical pro-inflammatory mechanism. Overall, the results suggest that the Khavinson Peptides^® cooperate as natural inducers of TNF tolerance in monocyte, and act on macrophages as anti-inflammatory molecules during inflammatory and microbial-mediated activity.

Lysosomes: Multifunctional compartments ruled by a complex regulatory network

More than 50 years have passed since Nobel laureate Cristian de Duve described for the first time the presence of tiny subcellular compartments filled with hydrolytic enzymes: the lysosome. For a long time, lysosomes were deemed simple waste bags exerting a plethora of hydrolytic activities involved in the recycling of biopolymers, and lysosomal genes were considered to just be simple housekeeping genes, transcribed in a constitutive fashion. However, lysosomes are emerging as multifunctional signalling hubs involved in multiple aspects of cell biology, both under homeostatic and pathological conditions. Lysosomes are involved in the regulation of cell metabolism through the mTOR/TFEB axis. They are also key players in the regulation and onset of the immune response. Furthermore, it is becoming clear that lysosomal hydrolases can regulate several biological processes outside of the lysosome. They are also implicated in a complex communication network among subcellular compartments that involves intimate organelle‐to‐organelle contacts. Furthermore, lysosomal dysfunction is nowadays accepted as the causative event behind several human pathologies: low frequency inherited diseases, cancer, or neurodegenerative, metabolic, inflammatory, and autoimmune diseases. Recent advances in our knowledge of the complex biology of lysosomes have established them as promising therapeutic targets for the treatment of different pathologies. Although recent discoveries have started to highlight that lysosomes are controlled by a complex web of regulatory networks, which in some cases seem to be cell‐ and stimuli‐dependent, to harness the full potential of lysosomes as therapeutic targets, we need a deeper understanding of the little‐known signalling pathways regulating this subcellular compartment and its functions.

Peucedanum japonicum Thunberg alleviates atopic dermatitis-like inflammation via STAT/MAPK signaling pathways in vivo and in vitro

Atopic dermatitis (AD) is a chronic, pruritic inflammatory skin disorder that exhibits clinical relapse. The disruption of the skin barrier increases the symptoms of AD, which is accompanied by a reduction in skin integrity. As an immune barrier, the skin plays a crucial role in regulating the inflammatory responses in AD. In this study, we used murine atopic dermatitis model using 2,4-dinitrochlorobenzen (DNCB), which is one of haptens to disrupt the skin barrier and generate the inflammation. As the small molecule, DNCB is easily penetrate the epidermis and binds to tissue proteins provoking immune responses. We evaluated the effects of an aqueous extract of Peucedanum japonicum Thunberg (PJT) in an experimental model of AD by measuring the mRNA and protein expression of cytokines and their related biomarkers. We examined the dorsal skin lesions, transepidermal water loss (TEWL), scratching behavior, expression of molecules related to skin barrier integrity, and histological changes in a murine model of DNCB- induced AD. We found out the down-regulatory effects of PJT on the AD-like symptoms or inflammatory dorsal lesions. For in vitro study, we used a mixture of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in human keratinocytes. The protein and mRNA expressions of skin barrier molecules and inflammatory markers were measured with western blotting and qRT-PCR assays, respectively. As a result, PJT alleviated the AD-like symptoms, and suppressed the inflammation caused by a TNF-α and IFN-γ in human keratinocytes. The regulatory effects of PJT appeared to be mediated via the mitogen-activated protein kinase (MAPK) and signal transducers and activators of transcription (STAT) signaling pathways both in vivo and in vitro. Altogether, the results indicated that PJT could serve as a promising therapeutic candidate for suppressing AD by inhibiting inflammation and improving the integrity of the skin barrier.

Molecular signaling pathways as potential therapeutic targets in osteosarcoma

Among primary bone malignancies, osteosarcoma (OS) is the most common form causing morbidity and mortality in both adults and children. The interesting point about this malignancy is that nearly 10-20% of its newly diagnosed cases have developed metastasis. This adds up to the fact that the survival rate of both metastatic and non-metastatic patients of osteosarcoma hasn't changed in the past 30 years and suggests that we need to revise our therapeutic options for OS. In recent years, diverse signaling pathways have drawn the attention of the scientific community since they can be great candidates for treating complicated diseases such as cancer. In this review, we have tried to explain the pathophysiology of osteosarcoma by the help of different signaling pathways taking part in its initiation/progression and investigate how this pathway can be targeted for providing more efficient methods.

Loss of Adipocyte STAT5 Confers Increased Depot-Specific Adiposity in Male and Female Mice That Is Not Associated With Altered Adipose Tissue Lipolysis

STATs (Signal Transducers and Activators of Transcription) 5A and 5B are induced during adipocyte differentiation and are primarily activated by growth hormone (GH) and prolactin in fat cells. Previous studies in mice lacking adipocyte GH receptor or STAT5 support their roles in lipolysis-mediated reduction of adipose tissue mass. Male and female mice harboring adipocyte-specific deletion of both STAT5 genes (STAT5^AKO) exhibit increased subcutaneous or inguinal adipose tissue mass, but no changes in visceral or gonadal fat mass. Both depots display substantial increases in adipocyte size with no changes in lipolysis in adipose tissue explants. RNA sequencing analysis of subcutaneous adipose tissue and indirect calorimetry experiments reveal sex-dependent differences in adipose gene expression and whole-body energy expenditure, respectively, resulting from the loss of adipocyte STAT5.

JAK2-STAT Epigenetically Regulates Tolerized Genes in Monocytes in the First Encounter With Gram-Negative Bacterial Endotoxins in Sepsis

Microbial challenges, such as widespread bacterial infection in sepsis, induce endotoxin tolerance, a state of hyporesponsiveness to subsequent infections. The participation of DNA methylation in this process is poorly known. In this study, we perform integrated analysis of DNA methylation and transcriptional changes following in vitro exposure to gram-negative bacterial lipopolysaccharide, together with analysis of ex vivo monocytes from septic patients. We identify TET2-mediated demethylation and transcriptional activation of inflammation-related genes that is specific to toll-like receptor stimulation. Changes also involve phosphorylation of STAT1, STAT3 and STAT5, elements of the JAK2 pathway. JAK2 pathway inhibition impairs the activation of tolerized genes on the first encounter with lipopolysaccharide. We then confirm the implication of the JAK2-STAT pathway in the aberrant DNA methylome of patients with sepsis caused by gram-negative bacteria. Finally, JAK2 inhibition in monocytes partially recapitulates the expression changes produced in the immunosuppressive cellular state acquired by monocytes from gram-negative sepsis, as described by single cell-RNA-sequencing. Our study evidences both the crucial role the JAK2-STAT pathway in epigenetic regulation and initial response of the tolerized genes to gram-negative bacterial endotoxins and provides a pharmacological target to prevent exacerbated responses.

Ruxolitinib Combined with Gemcitabine against Cholangiocarcinoma Growth via the JAK2/STAT1/3/ALDH1A3 Pathway

Cholangiocarcinoma is the most common primary malignant tumor of the bile duct. The current standard first-line treatment for advanced or metastatic cholangiocarcinoma is gemcitabine and cisplatin. However, few effective treatment choices exist for refractory cholangiocarcinoma, and additional therapeutic drugs are urgently required. Our previous work demonstrated that the ALDH isoform 1A3 plays a vital role in the malignant behavior of cholangiocarcinoma and may serve as a new therapeutic target. In this study, we found a positive correlation between ALDH1A3 protein expression levels and the cell migration abilities of three cholangiocarcinoma cell lines, which was verified using ALDH1A3-overexpressing and ALDH1A3-knockdown clones. We also used ALDH1A3-high and ALDH1A3-low populations of cholangiocarcinoma cell lines from the library of integrated network-based cellular signatures (LINCS) program and assessed the effects of ruxolitinib, a commercially available JAK2 inhibitor. Ruxolitinib had a higher cytotoxic effect when combined with gemcitabine. Furthermore, the nuclear translocation STAT1 and STAT3 heterodimers were markedly diminished by ruxolitinib treatment, possibly resulting in decreased ALDH1A3 activation. Notably, ruxolitinib alone or combined with gemcitabine led to significantly reduced tumor size and weight. Collectively, our studies suggest that ruxolitinib might suppress the ALDH1A3 activation through the JAK2/STAT1/3 pathway in cholangiocarcinoma, and trials should be undertaken to evaluate its efficacy in clinical therapy.

Crosstalk between nucleocytoplasmic trafficking and the innate immune response to viral infection

The nuclear pore complex is the sole gateway connecting the nucleoplasm and cytoplasm. In humans, the nuclear pore complex is one of the largest multiprotein assemblies in the cell, with a molecular mass of ∼110 MDa and consisting of 8 to 64 copies of about 34 different nuclear pore proteins, termed nucleoporins, for a total of 1000 subunits per pore. Trafficking events across the nuclear pore are mediated by nuclear transport receptors and are highly regulated. The nuclear pore complex is also used by several RNA viruses and almost all DNA viruses to access the host cell nucleoplasm for replication. Viruses hijack the nuclear pore complex, and nuclear transport receptors, to access the nucleoplasm where they replicate. In addition, the nuclear pore complex is used by the cell innate immune system, a network of signal transduction pathways that coordinates the first response to foreign invaders, including viruses and other pathogens. Several branches of this response depend on dynamic signaling events that involve the nuclear translocation of downstream signal transducers. Mounting evidence has shown that these signaling cascades, especially those steps that involve nucleocytoplasmic trafficking events, are targeted by viruses so that they can evade the innate immune system. This review summarizes how nuclear pore proteins and nuclear transport receptors contribute to the innate immune response and highlights how viruses manipulate this cellular machinery to favor infection. A comprehensive understanding of nuclear pore proteins in antiviral innate immunity will likely contribute to the development of new antiviral therapeutic strategies.

JAK-STAT in Early Hematopoiesis and Leukemia

Hematopoietic stem cells (HSCs) produce all the terminally differentiated blood cells and are controlled by extracellular signals from the microenvironment, the bone marrow (BM) niche, as well as intrinsic cell signals. Intrinsic signals include the tightly controlled action of signaling pathways, as the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway. Activation of JAK-STAT leads to phosphorylation of members of the STAT family to regulate proliferation, survival, and self-renewal of HSCs. Mutations in components of the JAK-STAT pathway are linked with defects in HSCs and hematologic malignancies. Accumulating mutations in HSCs and aging contribute to leukemia transformation. Here an overview of hematopoiesis, and the role of the JAK-STAT pathway in HSCs and in the promotion of leukemic transformation is presented. Therapeutic targeting of JAK-STAT and clinical implications of the existing research findings are also discussed.

Competitive binding of STATs to receptor phospho-Tyr motifs accounts for altered cytokine responses

Cytokines elicit pleiotropic and non-redundant activities despite strong overlap in their usage of receptors, JAKs and STATs molecules. We use IL-6 and IL-27 to ask how two cytokines activating the same signaling pathway have different biological roles. We found that IL-27 induces more sustained STAT1 phosphorylation than IL-6, with the two cytokines inducing comparable levels of STAT3 phosphorylation. Mathematical and statistical modeling of IL-6 and IL-27 signaling identified STAT3 binding to GP130, and STAT1 binding to IL-27Rα, as the main dynamical processes contributing to sustained pSTAT1 levels by IL-27. Mutation of Tyr613 on IL-27Rα decreased IL-27-induced STAT1 phosphorylation by 80% but had limited effect on STAT3 phosphorgylation. Strong receptor/STAT coupling by IL-27 initiated a unique gene expression program, which required sustained STAT1 phosphorylation and IRF1 expression and was enriched in classical Interferon Stimulated Genes. Interestingly, the STAT/receptor coupling exhibited by IL-6/IL-27 was altered in patients with systemic lupus erythematosus (SLE). IL-6/IL-27 induced a more potent STAT1 activation in SLE patients than in healthy controls, which correlated with higher STAT1 expression in these patients. Partial inhibition of JAK activation by sub-saturating doses of Tofacitinib specifically lowered the levels of STAT1 activation by IL-6. Our data show that receptor and STATs concentrations critically contribute to shape cytokine responses and generate functional pleiotropy in health and disease.

Anti-Inflammatory Effects of Ellagic Acid on Keratinocytes via MAPK and STAT Pathways

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is characterized by an impaired skin barrier and intense itchiness, which decreases the individual’s quality of life. No fully effective therapeutic agents have prevailed for AD due to an insufficient grasp of the complex etiology. Ellagic acid (EA), a natural compound, has anti-inflammatory properties in chronic diseases. The effects of EA on AD have not yet been explored. The present study investigated the effects of EA on TNF-α/IFN-γ-stimulated HaCaT keratinocytes and house dust mite-induced AD-like skin lesions in NC/Nga mice. Treatment with EA suppressed inflammatory responses in keratinocytes by regulating critical inflammatory signaling pathways, such as mitogen-activated protein kinases and signal transducers and activators of transcription. In vivo studies using a DfE-induced AD mouse model showed the effects of EA administration through ameliorated skin lesions via decremented histological inflammatory reactions. These results suggest that EA could be a potential therapeutic alternative for the treatment of AD by inhibiting inflammatory signaling pathways.

Cynaropicrin Shows Antitumor Progression Potential in Colorectal Cancer Through Mediation of the LIFR/STATs Axis

BACKGROUND

Colorectal cancer (CRC) is the second deadliest malignant disease in the world and the leukemia inhibitory factor receptor/signal transducers and activators of transcriptions (LIFR/STATs) signaling axis plays an important role in the molecular biology of CRC.

METHODS

Cell function tests were performed to observe the inhibitory effect of cynaropicrin on human CRC cells (RKO, HCT116, and DLD-1). Expression levels of LIFR, P-STAT3, P-STAT4, and apoptotic proteins were detected by Western blotting. Immunoprecipitation confirmed the presence of LIFR/STAT3/STAT4 complex. Cell immunofluorescence assay was used to observe the subcellular localization of STAT3 and STAT4. In vivo efficacy of cynaropicrin was evaluated by a xenotransplantation model in nude mice.

RESULTS

Cynaropicrin significantly reduced the survival ability of human CRC cells and promoted apoptosis in a dose-dependent manner. Western blotting results suggested that the antitumor effects of cynaropicrin might be mediated by inhibition of the LIFR/STATs axis. Cynaropicrin reduced the formation of STAT3/STAT4 heterodimers and blocked their entry into the nucleus. Cynaropicrin also suppressed tumor growth in the xenograft model.

CONCLUSION

The results showed that cynaropicrin exerted a strong inhibitory effect on CRC in vitro and in vivo. Our study concluded that cynaropicrin has potential application prospects in the field of anti-CRC therapy.

Role of the JAK-STAT Pathway in Bovine Mastitis and Milk Production

Simple Summary

The cytokine-activated Janus kinase (JAK)—signal transducer and activator of transcription (STAT) pathway has an important role in the regulation of immunity and inflammation. In addition, the signaling of this pathway has been reported to be associated with mammary gland development and milk production. Because of such important functions, the JAK-STAT pathway has been widely targeted in both human and animal diseases as a therapeutic agent. Recently, the JAK2, STATs, and inhibitors of the JAK-STAT pathway, especially cytokine signaling suppressors (SOCSs), have been reported to be associated with milk production and mastitis-resistance phenotypic traits in dairy cattle. Thus, in the current review, we attempt to overview the development of the JAK-STAT pathway role in bovine mastitis and milk production.

Abstract

The cytokine-activated Janus kinase (JAK)—signal transducer and activator of transcription (STAT) pathway is a sequence of communications between proteins in a cell, and it is associated with various processes such as cell division, apoptosis, mammary gland development, lactation, anti-inflammation, and immunity. The pathway is involved in transferring information from receptors on the cell surface to the cell nucleus, resulting in the regulation of genes through transcription. The Janus kinase 2 (JAK2), signal transducer and activator of transcription A and B (STAT5 A & B), STAT1, and cytokine signaling suppressor 3 (SOCS3) are the key members of the JAK-STAT pathway. Interestingly, prolactin (Prl) also uses the JAK-STAT pathway to regulate milk production traits in dairy cattle. The activation of JAK2 and STATs genes has a critical role in milk production and mastitis resistance. The upregulation of SOCS3 in bovine mammary epithelial cells inhibits the activation of JAK2 and STATs genes, which promotes mastitis development and reduces the lactational performance of dairy cattle. In the current review, we highlight the recent development in the knowledge of JAK-STAT, which will enhance our ability to devise therapeutic strategies for bovine mastitis control. Furthermore, the review also explores the role of the JAK-STAT pathway in the regulation of milk production in dairy cattle.

Mining therapeutic and prognostic significance of STATs in renal cell carcinoma with bioinformatics analysis

Renal cell carcinoma is one of the most common malignancies with high morbidity and mortality. STAT proteins play a significant role in cell biological behavior and immune response associated with cancer progression. In our study, the datasets analyzed for the expression and potential functions can be found in several bioinformatics analysis tools. We found that STAT1/2/4/6 were upregulated in RCC while STAT3/5B were downregulated. The expression of STAT2/4/5B were significantly associated with the pathological stage of RCC patients. RCC patients with high expression of STAT2/4 and low/medium expression of STAT5B had a poor overall survival. The function of STATs and the neighboring genes mainly enriched in JAK-STAT signaling pathway and NOD-like receptor signaling pathway. Several transcription factor, kinase, and miRNA targets were identified. Close correlations were obtained between immune cell infiltration and STATs in RCC. Our results have provided novel insights for the selection of immunotherapeutic targets and prognostic biomarkers.

Aqueous extract of Fritillariae cirrhosae induces cellular apoptosis through activation of STATs-mediated immunomodulation

ETHNOPHARMACOLOGICAL RELEVANCE

Fritillariae cirrhosae (FC), referred to'Chuan beimu'in China. As an important edible and medicinal plant, the bulbs of F.cirrhosae is used traditionally in the treatment of pulmonary diseases associated with lung heat, inflammation and tumors. In the study, we investigated the effect of aqueous extract of FC (FC-AE) and elucidated its mechanism in non-small cell lung cancer A549 cells and a xenograft model of nude mice.

MATERIALS AND METHODS

CCK-8 and plate colony formation assay were used to evaluate the effect of FC-AE in A549 cells in vitro, and the gene expression profile of FC-AE on A549 cells was assessed by RNA sequencing system. Then, the effects of FC-AE on cell cycle and apoptosis of A549 cells were analyzed by flow cytometry. In combination with RNA-seq data, RT-PCR and western blot were used to evaluate the expression of proteins related to apoptosis and immune regulation. A xenograft model of nude mice was used to assess the effect of FC-AE in vivo.

RESULTS

CCK-8 and plate cloning assays showed that FC-AE inhibited the proliferation and colony formation of A549 cells. A549 cells treated with FC-AE can triggered apoptosis. GO and KEGG pathway enrichment analysis of RNA-seq data showed that most of the differentially expressed genes (DEGs) were related to immune response, apoptosis and cell cycle process. Several immune and apoptotic DEGs were identified by qRT-PCR which were consistented with RNA-seq data. In nude mice, FC-AE reduced the tumor size and promoted the secretion of cytokines IL12 and IFNγ. FC-AE up-regulated the two members (STAT1 and STAT4) of STATs and their target genes (IFNγ and IL-12, respectively) protein expressions, and actively regulates Bcl-2/Bax family proteins which resulted in cellular apoptosis in A549 cells.

CONCLUSION

Our finding suggests that FC-AE mediates apoptosis through a STAT1 and STAT4-mediated co-regulatory network, which may be the key novel mechanism for its antitumor activity. The F. cirrhosa may be a promising antitumor drug for modulating immune responses to improve cancer therapy.

SARS-CoV-2 Orf6 hijacks Nup98 to block STAT nuclear import and antagonize interferon signaling

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic that is a serious global health problem. Evasion of IFN-mediated antiviral signaling is a common defense strategy that pathogenic viruses use to replicate and propagate in their host. In this study, we show that SARS-CoV-2 is able to efficiently block STAT1 and STAT2 nuclear translocation in order to impair transcriptional induction of IFN-stimulated genes (ISGs). Our results demonstrate that the viral accessory protein Orf6 exerts this anti-IFN activity. We found that SARS-CoV-2 Orf6 localizes at the nuclear pore complex (NPC) and directly interacts with Nup98-Rae1 via its C-terminal domain to impair docking of cargo-receptor (karyopherin/importin) complex and disrupt nuclear import. In addition, we show that a methionine-to-arginine substitution at residue 58 impairs Orf6 binding to the Nup98-Rae1 complex and abolishes its IFN antagonistic function. All together our data unravel a mechanism of viral antagonism in which a virus hijacks the Nup98-Rae1 complex to overcome the antiviral action of IFN.

A p53-JAK-STAT connection involved in myeloproliferative neoplasm pathogenesis and progression to secondary acute myeloid leukemia

Since the discovery of JAK2 V617F as a highly prevalent somatic acquired mutation in the majority of myeloproliferative neoplasms (MPNs), it has become clear that these diseases are driven by pathologic activation of JAK2 and eventually of STAT5 and other members of the STAT family. The concept was strengthened by the discovery of the other activating driver mutations in MPL (thrombopoietin receptor, TpoR) and in calreticulin gene, which all lead to persistent activation of wild type JAK2. Although with a rare frequency, MPNs can evolve to secondary acute myeloid leukemia (sAML), a condition that is resistant to treatment. Here we focus on the role of p53 in this transition. In sAML mutations in TP53 or amplification in genes coding for negative regulators of p53 are much more frequent than in de novo AML. We review studies that explore a signaling and biochemical interaction between activated STATs and p53 in MPNs and other cancers. With the development of advanced sequencing efforts, strong evidence has been presented for dominant negative effects of mutated p53 in leukemia. In other studies, gain of function effects have been described that might be cell type specific. A more profound understanding of the potential interaction between p53 and activated STATs is necessary in order to take full advantage of novel p53-targeted therapies.

Hi-JAKi-ng Synovial Fibroblasts in Inflammatory Arthritis With JAK Inhibitors

The Janus kinase (JAK)-Signal transducer and activator of transcription (STAT) pathway is one of the central signaling hubs in inflammatory, immune and cancer cells. Inhibiting the JAK-STAT pathway with JAK inhibitors (jakinibs) constitutes an important therapeutic strategy in cancer and chronic inflammatory diseases like rheumatoid arthritis (RA). FDA has approved different jakinibs for the treatment of RA, including tofacitinib, baricitinib and upadacitinib, and several jakinibs are being tested in clinical trials. Here, we reviewed published studies of jakinib effects on resolving synovial pathology in inflammatory arthritis. We discussed the results of jakinibs on structural joint damage in clinical trials and explored the effects of jakinibs across different in vitro, ex vivo, and in vivo synovial experimental models. We delved rigorously into experimental designs of in vitro fibroblast studies, deconvoluted jakinib efficacy in synovial fibroblasts across diverse experimental conditions and discussed their translatability in vivo. Synovial fibroblasts can readily activate the JAK-STAT signaling pathway in response to cytokine stimulation. We highlighted rather limited effects of jakinibs on the in vitro cultured synovial fibroblasts and inferred that direct and indirect (immune cell-dependent) actions of jakinibs are required to curb the fibroblast pathology in vivo. These actions have not been mimicked optimally in current in vitro experimental designs, where inflammatory stimuli do not naturally clear out with treatment as they do in vivo. While summarizing the broad knowledge of synovial jakinib effects, our review uniquely challenges future study designs to better mimick the jakinib actions in broader cell communities, as occurring in vivo in the inflamed synovium. This can deepen our understanding of collective synovial activities of jakinibs and their therapeutic limitations, thereby fostering jakinib development in arthritis.

Natural pseurotins and analogs thereof inhibit activation of B-cells and differentiation into the plasma cells

BACKGROUND

The frequency of allergic diseases is constantly rising. Dysregulated production of isotype E immunoglobulins is one of the key factors behind allergic reactions and its modulation is therefore an important target for pharmacological intervention. Natural products of the pseurotin family were reported to be inhibitors of IgE production in B-cells. Mechanistic details underlying these effects are however not well understood.

PURPOSE

In the present study, we synthesized new analogs of natural pseurotins and extensively investigated their inhibitory effects on activation, proliferation and differentiation of B-cells, as well as on the production of IgE.

STUDY DESIGN

Effects of two natural pseurotins (pseurotins A and D) and a collection of fully synthetic pseurotin analogs were studied on mouse B-cells stimulated by the combination of IL-4 and E. coli lipopolysaccharide. The IgE production was determined along with cell viability and cell proliferation. The phosphorylation of selected members of the STAT transcription factor family was subsequently investigated. Finally, the in vivo effect of pseurotin D on the ovalbumin-induced delayed type hypersensitivity response was tested in mice.

RESULTS

We discovered that several fully synthetic pseurotin analogs were able to decrease the production of IgE in stimulated B-cells with potency comparable to that of pseurotins A and D. We found that the two natural pseurotins and the active synthetic analogs inhibited the phosphorylation of STAT3, STAT5 and STAT6 proteins in stimulated B-cells, resulting in the inhibition of B-cell proliferation and differentiation into the plasma cells. In vivo, pseurotin D decreased ovalbumin-induced foot pad edema.

CONCLUSION

Our results advance the current mechanistic understanding of the pseurotin-induced inhibition of IgE production in B-cells by linking the effect to STAT signaling, and associated modulation of B-cell proliferation and differentiation. Together with our finding that structurally simpler pseurotin analogs were able to reproduce the effects of natural pseurotins, the presented work has implications for the future research on these secondary metabolites in the context of allergic diseases.

Assessing Phosphorylation of STAT Transcription Factors in Mouse Innate Lymphoid Cells

Innate lymphoid cells (ILCs) ensure protection against pathogens by quickly reacting to the alterations of the cytokine milieu taking place upon infection. More than 50 cytokines and growth factors activate the Janus kinases (JAKs), leading to phosphorylation of members of the signal transducer and activator of transcription (STAT) family. Activation of STATs induces specific transcriptional programs which are associated with distinct cellular outcomes. Thus, an efficient measurement of rapid STAT phosphorylation enables not only to dissect the spectrum of cytokine sensitivity among ILC subsets but also to pinpoint specific transcriptional programs and cellular functions initiated after activation. Using this method, we have previously dissected the downstream events of Interleukin (IL)-23 and IL-12 signaling in ILCs, shedding light on the differential usage of STATs among ILC subsets. Here, we provide an optimized and detailed protocol describing how to analyze phosphorylation of STAT transcription factors in murine NK and ILC subsets isolated from different tissues.

TYK2 in Tumor Immunosurveillance

We review the history of the tyrosine kinase 2 (TYK2) as the founding member of the Janus kinase (JAK) family and outline its structure-function relation. Gene-targeted mice and hereditary defects of TYK2 in men have established the biological and pathological functions of TYK2 in innate and adaptive immune responses to infection and cancer and in (auto-)inflammation. We describe the architecture of the main cytokine receptor families associated with TYK2, which activate signal transducers and activators of transcription (STATs). We summarize the cytokine receptor activities with well characterized dependency on TYK2, the types of cells that respond to cytokines and TYK2 signaling-induced cytokine production. TYK2 may drive beneficial or detrimental activities, which we explain based on the concepts of tumor immunoediting and the cancer-immunity cycle in the tumor microenvironment. Finally, we summarize current knowledge of TYK2 functions in mouse models of tumor surveillance. The biology and biochemistry of JAKs, TYK2-dependent cytokines and cytokine signaling in tumor surveillance are well covered in recent reviews and the oncogenic properties of TYK2 are reviewed in the recent Special Issue ‘Targeting STAT3 and STAT5 in Cancer’ of Cancers.

Taking a holistic view of PEST-containing nuclear protein (PCNP) in cancer biology

Polypeptide sequences enriched with proline (P), glutamic acid (E), aspartic acid (D) and serine (S)/ threonine (T) (PEST) have been reported to be the most abundant and frequently distributed at the cellular level. There is growing evidence that PEST sequences act as proteolytic recognition signals for degradation of residual proteins which is critical for activation or deactivation of regulatory proteins involved in cellular signaling pathways of cell growth, differentiation, stress responses and physiological death. A PEST containing nuclear protein (PCNP) was demonstrated as a tumor suppressor in a neuroblastoma cancer model and tumor promoter in lung adenocarcinoma cancer model. Its unique properties like ubiquitination by NIRF, co‐localization with NIRF in nucleus and tumor progression attract the attention of researchers. PCNP was reported to be ubiquitinated by ring finger protein NIRF in E3 ligase manner and as modulator of MAPK and PI3K/AKT/mTOR signaling pathways. In this review, we summarize PCNP linked DNA damage response, Post translational modifications, and transportation to address initiation, prognosis, and resistance of tumor cells in terms of cell cycle regulation, transcription and apoptosis. Hence, we demonstrate PCNP as a novel target in cancer diagnosis and treatment.

AKR1C1 controls cisplatin-resistance in head and neck squamous cell carcinoma through cross-talk with the STAT1/3 signaling pathway

Background

Cisplatin is the first-line chemotherapy used against most upper aerodigestive tract carcinomas. In head and neck cancer, sensitivity to cisplatin remains the key issue in treatment response and outcome. Genetic heterogeneity and aberrant gene expression may be the intrinsic factors that cause primary cisplatin-resistance.

Methods

Combination of the HNSCC gene expression data and the cisplatin sensitivity results from public database. We found that aldo-keto reductase family 1 member C1 (AKR1C1) may be associated with cisplatin sensitivity in HNSCC treatment of naïve cells. We examined the AKR1C1 expression and its correlation with cisplatin IC₅₀ and prognosis in patients. The in vitro and in vivo AKR1C1 functions in cisplatin-resistance through overexpression or knockdown assays, respectively. cDNA microarrays were used to identify the upstream regulators that modulate AKR1C1-induced signaling in HNSCC. Finally, we used the cigarette metabolites to promote AKR1C1 expression and ruxolitinib to overcome AKR1C1-induced cisplatin-resistance.

Results

AKR1C1 positively correlates to cisplatin-resistance in HNSCC cells. AKR1C1 is a poor prognostic factor for recurrence and death of HNSCC patients. Silencing of AKR1C1 not only reduced in vitro IC₅₀ but also increased in vivo cisplatin responses and vise versa in overexpression cells. Cigarette metabolites also promote AKR1C1 expression. Transcriptome analyses revealed that STAT1 and STAT3 activation enable AKR1C1-induced cisplatin-resistance and can be overcome by ruxolitinib treatment.

Conclusions

AKR1C1 is a crucial regulator for cisplatin-resistance in HNSCC and also poor prognostic marker for patients. Targeting the AKR1C1-STAT axis may provide a new therapeutic strategy to treat patients who are refractory to cisplatin treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1256-2) contains supplementary material, which is available to authorized users.

Prognostic values of signal transducers activators of transcription in gastric cancer

The signal transducers and activators of transcription genes family (STATs) have been well studied as prognostic predictors for various solid tumors, but their prognostic values in gastric cancer (GC) patients have not been fully elucidated. The 'Kaplan-Meier plotter' and multiple public available databases were used for the characterization of the prognostic roles of STATs family in GC. The results indicated that high mRNA expression of all individual STATs, except STAT3 and STAT6, were significantly associated with favorable overall survival (OS) in GC. Moreover, the prognostic values of STATs were further characterized in subtypes, including HER2 status, Lauren's classification, differentiation, and clinical stages. Moreover, the prognostic value of STATs signature was also characterized. Low risk group displayed a significantly favorable OS than high risk (HR: 1.71; 95% CI: 1.09-2.66, P=0.0184). In addition, STATs showed distinct expression between GC and normal groups. Meanwhile, comparable high correlation between STATs and tumor immune infiltrating cells (TIICs) was also observed. STAT4 displayed highest correlation with dendritic cells (correlation = 0.716, P=1.63e-59) and CD8⁺ T cells (correlation = 0.697, P=5.02e-55). In conclusion, our results suggest that all individual STATs, except STAT3 and STAT6, may act as prognostic markers in GC.

DHAV-1 Inhibits Type I Interferon Signaling to Assist Viral Adaption by Increasing the Expression of SOCS3

Duck hepatitis A virus type 1 (DHAV-1) is one of the most lethal pathogens in the duck industry. The attenuated vaccine (the CH60 strain) is cultivated through serial passage in chicken embryos and is widely used for the prevention and control of the disease. However, the specific mechanism underlying its adaptation in chicken embryos has not been fully elucidated. In this study, we first infected chicken embryo fibroblasts (CEFs) with the DHAV-1 CH60 strain. The peak of viral proliferation occurred within 36–48 h post-infection. The different DHAV-1 strains significantly induced the expression of IFNα, IFNγ, and Suppressor of cytokine signaling 3 (SOCS3) in CEFs, and we found that SOCS3 overexpression significantly promoted viral replication. Furthermore, SOCS3 overexpression significantly inhibited the expression of IFNα but promoted the expression of IFNγ. In addition, SOCS3 overexpression clearly decreased the mRNA levels of STAT1 and STAT3 in the Janus kinase (JAK)-STAT signaling pathway and inhibited the expression of the antiviral proteins MX1 and OASL. Immune-precipitation assays indicated that SOCS3 and IFNα do not physically interact. Subcellular localization of SOCS3 and IFNα revealed that SOCS3 was mainly located in the nucleus and cytoplasm, while IFNα was located only in the cytoplasm. Co-localization of these two proteins was not observed in the cytoplasm. In conclusion, the DHAV-1 CH60 strain may inhibit the expression of IFNα by increasing the SOCS3 protein and SOCS3 can in turn decrease STAT1 and STAT3 mRNA levels, thereby inhibiting the antiviral protein MX1 and ultimately promoting viral proliferation, indirectly assisting in viral adaptation in chicken embryos.

Translational and clinical advances in JAK-STAT biology: The present and future of jakinibs

In this era, it is axiomatic that cytokines have critical roles in cellular development and differentiation, immune homeostasis, and host defense. Equally, dysregulation of cytokines is known to contribute to diverse inflammatory and immune-mediated disorders. In fact, the past 20 years have witnessed the rapid translation of basic discoveries in cytokine biology to multiple successful biological agents (mAbs and recombinant fusion proteins) that target cytokines. These targeted therapies have not only fundamentally changed the face of multiple immune-mediated diseases but have also unequivocally established the role of specific cytokines in human disease; cytokine biologists have many times over provided remarkable basic advances with direct clinical benefit. Numerous cytokines rely on the JAK-STAT pathway for signaling, and new, safe, and effective small molecule inhibitors have been developed for a range of disorders. In this review, we will briefly summarize basic discoveries in cytokine signaling and briefly comment on some major unresolved issues. We will review clinical data pertaining to the first generation of JAK inhibitors and their clinical indications, discuss additional opportunities for targeting this pathway, and lay out some of the challenges that lie ahead.

MRTF-A mediated FN and ICAM-1 expression in AGEs-induced rat glomerular mesangial cells via activating STAT5

Advanced glycation end products (AGEs), formed at an accelerated rate under diabetes, play a role in inflammation and fibrosis in mesangial areas in diabetic nephropathy (DN). However, the transcriptional modulator that mediates the cellular response to AGEs remains largely obscure. Our goal was to determine whether myocardin-related transcription factor (MRTF)-A, a key protein involved in the transcriptional regulation of smooth muscle cell phenotype, was responsible for the glomerular mesangial cells (GMCs) injury by AGEs, and, if so, how MRTF-A promoted mesangial dysfunction initiated by AGEs. In this study, MRTF-A was activated by AGEs in terms of protein expression and nuclear translocation in rat GMCs. MRTF-A overexpression synergistically enhanced the induction of FN and ICAM-1 by AGEs. In contract, depletion of MRTF-A abrogated the pathogenic program triggered by AGEs. Then, by interfering with MRTF-A, STAT1, STAT3 and STAT5 nuclear translocation were observed and we screened out STAT5, which was decreased obviously when MRTF-A depleted. Further investigation showed that MRTF-A interacted with STAT5 and promoted its nuclear accumulation and transcriptional activity. Therefore, our present findings suggested a role of MRTF-A in AGEs-induced GMCs injury, and further revealed that the underlying molecular mechanism was related to activating the nuclear factor STAT5.

IL-12p35 Inhibits Neuroinflammation and Ameliorates Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is an inflammatory demyelinating disease in which cytokines produced by immune cells that infiltrate the brain and spinal cord play a central role. We show here that the IL-12p35, the alpha subunit of IL-12 or IL-35 cytokine, might be an effective biologic for suppressing neuroinflammatory responses and ameliorating the pathology of experimental autoimmune encephalomyelitis (EAE), the mouse model of human MS. We further show that IL-12p35 conferred protection from neuropathy by inhibiting the expansion of pathogenic Th17 and Th1 cells and inhibiting trafficking of inflammatory cells into the brain and spinal cord. In addition, in vitro exposure of encephalitogenic cells to IL-12p35 suppressed their capacity to induce EAE by adoptive transfer. Importantly, the IL-12p35-mediated expansion of Treg and Breg cells and its amelioration of EAE correlated with inhibition of cytokine-induced activation of STAT1/STAT3 pathways. Moreover, IL-12p35 inhibited lymphocyte proliferation by suppressing the expressions of cell-cycle regulatory proteins. Taken together, these results suggest that IL-12p35 can be exploited as a novel biologic for treating central nervous system autoimmune diseases and offers the promise of ex vivo production of large amounts of Tregs and Bregs for immunotherapy.

New insights into Blimp-1 in T lymphocytes: a divergent regulator of cell destiny and effector function

B lymphocyte-induced maturation protein-1 (Blimp-1) serves as a master regulator of the development and function of antibody-producing B cells. Given that its function in T lymphocytes has been identified within the past decade, we review recent findings with emphasis on its role in coordinated control of gene expression during the development, differentiation, and function of T cells. Expression of Blimp-1 is mainly confined to activated T cells and is essential for the production of interleukin (IL)-10 by a subset of forkhead box (Fox)p3⁺ regulatory T cells with an effector phenotype. Blimp-1 is also required to induce cell elimination in the thymus and critically modulates peripheral T cell activation and proliferation. In addition, Blimp-1 promotes T helper (Th) 2 lineage commitment and limits Th1, Th17 and follicular helper T cell differentiation. Furthermore, Blimp-1 coordinates with other transcription factors to regulate expression of IL-2, IL-21 and IL-10 in effector T lymphocytes. In CD8⁺ T cells, Blimp-1 expression is distinct in heterogeneous populations at the stages of clonal expansion, differentiation, contraction and memory formation when they encounter antigens. Moreover, Blimp-1 plays a fundamental role in coordinating cytokine receptor signaling networks and transcriptional programs to regulate diverse aspects of the formation and function of effector and memory CD8⁺ T cells and their exhaustion. Blimp-1 also functions as a gatekeeper of T cell activation and suppression to prevent or dampen autoimmune disease, antiviral responses and antitumor immunity. In this review, we discuss the emerging roles of Blimp-1 in the complex regulation of gene networks that regulate the destiny and effector function of T cells and provide a Blimp-1-dominated transcriptional framework for T lymphocyte homeostasis.

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 prognostic roles of the STAT family in ovarian carcinoma through the ‘Kaplan–Meier plotter’ (KM plotter) online database, which collected gene expression data and survival information (overall survival (OS)) from a total of 1582 ovarian cancer patients. Our results show that high mRNA expression of STAT1, STAT4, STAT5a, STAT5b, and STAT6, are correlated to a better OS of ovarian cancer patients, especially the high level of STAT1 and STAT4 are significantly related to a favorable OS for serous ovarian cancer patients. We further accessed the prognostic roles of individual STATs in other clinicopathological features, such as pathological grades, clinical stages, and TP53 mutation, and found that these genes indicate a favorable prognosis especially for late stage, poor differentiation, and TP53 mutated ovarian cancer patients. In conclusion, these results suggest that the STAT family plays a significant prognostic role in ovarian carcinoma and individual STATs, except STAT2 and STAT3, may act as favorable prognostic markers in ovarian cancer.

STAT5-Interacting Proteins: A Synopsis of Proteins that Regulate STAT5 Activity

Signal Transducers and Activators of Transcription (STATs) are key components of the JAK/STAT pathway. Of the seven STATs, STAT5A and STAT5B are of particular interest for their critical roles in cellular differentiation, adipogenesis, oncogenesis, and immune function. The interactions of STAT5A and STAT5B with cytokine/hormone receptors, nuclear receptors, transcriptional regulators, proto-oncogenes, kinases, and phosphatases all contribute to modulating STAT5 activity. Among these STAT5 interacting proteins, some serve as coactivators or corepressors to regulate STAT5 transcriptional activity and some proteins can interact with STAT5 to enhance or repress STAT5 signaling. In addition, a few STAT5 interacting proteins have been identified as positive regulators of STAT5 that alter serine and tyrosine phosphorylation of STAT5 while other proteins have been identified as negative regulators of STAT5 via dephosphorylation. This review article will discuss how STAT5 activity is modulated by proteins that physically interact with STAT5.

NADPH oxidase-derived H2O2 mediates the regulatory effects of microglia on astrogliosis in experimental models of Parkinson's disease

Astrogliosis has long been recognized in Parkinson's disease (PD), the most common neurodegenerative movement disorder. However, the mechanisms of how astroglia become activated remain unclear. Reciprocal interactions between microglia and astroglia play a pivotal role in regulating the activities of astroglia. The purpose of this study is to investigate the mechanism by which microglia regulate astrogliosis by using lipopolysaccharide (LPS) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse PD models. We found that the activation of microglia preceded astroglia in the substantia nigra of mice treated with either LPS or MPTP. Furthermore, suppression of microglial activation by pharmacological inhibition or genetic deletion of NADPH oxidase (NOX2) in mice attenuated astrogliosis. The important role of NOX2 in microglial regulation of astrogliosis was further mirrored in a mixed-glia culture system. Mechanistically, H₂O₂, a product of microglial NOX2 activation, serves as a direct signal to regulate astrogliosis. Astrogliosis was induced by H₂O₂ through a process in which extracellularly generated H₂O₂ diffused into the cytoplasm and subsequently stimulated activation of transcription factors, STAT1 and STAT3. STAT1/3 activation regulated the immunological functions of H₂O₂-induced astrogliosis since AG490, an inhibitor of STAT1/3, attenuated the gene expressions of both proinflammatory and neurotrophic factors in H₂O₂-treated astrocyte. Our findings indicate that microglial NOX2-generated H₂O₂ is able to regulate the immunological functions of astroglia via a STAT1/3-dependent manner, providing additional evidence for the immune pathogenesis and therapeutic studies of PD.

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Microglia are capable of regulating the immunological functions of astrogliosis in Parkinson's disease.

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NADPH oxidase-derived H₂O₂ is recognized as a paracrine signal for microglial regulation of astrogliosis.

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Transcription factors STAT1 and STAT3 play pivotal roles in H₂O₂-induced astroglial activation.

The differentiation and plasticity of Tc17 cells are regulated by CTLA-4-mediated effects on STATs

As the blockade of inhibitory surface-molecules such as CTLA-4 on T cells has led to recent advances in antitumor immune therapy, there is great interest in identifying novel mechanisms of action of CD8⁺ T cells to evoke effective cytotoxic antitumor responses. Using in vitro and in vivo models, we investigated the molecular pathways underlying the CTLA-4-mediated differentiation of IL-17-producing CD8⁺ T cells (Tc17 cells) that strongly impairs cytotoxicity. Our studies demonstrate that Tc17 cells lacking CTLA-4 signaling have limited production of STAT3-target gene products such as IL-17, IL-21, IL-23R and RORγt. Upon re-stimulation with IL-12, these cells display fast downregulation of Tc17 hallmarks and acquire Tc1 characteristics such as IFNγ and TNF-α co-expression, which is known to correlate with tumor control. Indeed, upon adoptive transfer, these cells were highly efficient in the antigen-specific rejection of established OVA-expressing B16 melanoma in vivo. Mechanistically, in primary and re-stimulated Tc17 cells, STAT3 binding to the IL-17 promoter was strongly augmented by CTLA-4, associated with less binding of STAT5 and reduced relative activation of STAT1 which is known to block STAT3 activity. Inhibiting CTLA-4-induced STAT3 activity reverses enhancement of signature Tc17 gene products, rendering Tc17 cells susceptible to conversion to Tc1-like cells with enhanced cytotoxic potential. Thus, CTLA-4 critically shapes the characteristics of Tc17 cells by regulating relative STAT3 activation, which provides new perspectives to enhance cytotoxicity of antitumor responses.

Antagonizing cytokine-mediated JAK-STAT signaling by porcine reproductive and respiratory syndrome virus

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PRRSV inhibits the interferon-activated JAK-STAT1/STAT2 signaling.

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PRRSV nsp1β induces degradation of KPNA1 to block the STAT1 nuclear translocation.

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PRRSV nsp5 reduces STAT3 to inhibit the JAK-STAT3 signaling.

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PRRSV may interfere with other STAT signaling and antagonizes ISGs.

Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway is activated by myriad cytokines, which are involved in regulation of cell growth, proliferation, differentiation, apoptosis, angiogenesis, immunity and inflammatory response. Because of its significance in immune response, JAK-STAT pathway is often targeted by pathogens, including porcine reproductive and respiratory syndrome virus (PRRSV). PRRSV causes reproductive failure in sows and respiratory disease in pigs of all ages. A typical feature of the immune response to PRRSV infection in pigs is delayed production and low titer of virus neutralizing antibodies, and weak cell-mediated immune response. One of the possible reasons for the weak protective immune response is that PRRSV interferes with cytokine-mediated JAK-STAT signaling. PRRSV inhibits interferon-activated JAK-STAT signaling by blocking nuclear translocation of STAT1 and STAT2. The mechanism is that PRRSV non-structural protein 1β (nsp1β) induces degradation of karyopherin α1 (KPNA1), a critical adaptor in nucleo-cytoplasmic transport. PRRSV also antagonizes IL6-activated JAK-STAT3 signaling via inducing degradation of STAT3. In this review, we briefly introduce JAK-STAT signaling, summarize the PRRSV interference with it, and provide perspective on the perturbation in the context of PRRSV-elicited immune response.

Loss of Oncostatin M Signaling in Adipocytes Induces Insulin Resistance and Adipose Tissue Inflammation in Vivo

Oncostatin M (OSM) is a multifunctional gp130 cytokine. Although OSM is produced in adipose tissue, it is not produced by adipocytes. OSM expression is significantly induced in adipose tissue from obese mice and humans. The OSM-specific receptor, OSM receptor β (OSMR), is expressed in adipocytes, but its function remains largely unknown. To better understand the effects of OSM in adipose tissue, we knocked down Osmr expression in adipocytes in vitro using siRNA. In vivo, we generated a mouse line lacking Osmr in adiponectin-expressing cells (OSMR(FKO) mice). The effects of OSM on gene expression were also assessed in vitro and in vivo OSM exerts proinflammatory effects on cultured adipocytes that are partially rescued by Osmr knockdown. Osm expression is significantly increased in adipose tissue T cells of high fat-fed mice. In addition, adipocyte Osmr expression is increased following high fat feeding. OSMR(FKO) mice exhibit increased insulin resistance and adipose tissue inflammation and have increased lean mass, femoral length, and bone volume. Also, OSMR(FKO) mice exhibit increased expression of Osm, the T cell markers Cd4 and Cd8, and the macrophage markers F4/80 and Cd11c Interestingly, the same proinflammatory genes induced by OSM in adipocytes are induced in the adipose tissue of the OSMR(FKO) mouse, suggesting that increased expression of proinflammatory genes in adipose tissue arises both from adipocytes and other cell types. These findings suggest that adipocyte OSMR signaling is involved in the regulation of adipose tissue homeostasis and that, in obesity, OSMR ablation may exacerbate insulin resistance by promoting adipose tissue inflammation.

Developmental expression of STATs, nuclear factor-κB and inflammatory genes in the jejunum of piglets during weaning

The signal transducer and activator of transcription (STAT) proteins play essential roles in apoptosis, proliferation and survival. However, the role of STATs in intestinal inflammation during weaning is unclear. This study aimed to investigate developmental expression of STATs, nuclear factor-κB (NF-κB) and inflammatory genes in the jejunum of piglets during weaning. Thirty-two piglets were weaned at 21d and sacrificed at 0, 1, 7, or 14d (n=8) after weaning. Villus height and the villus height/crypt depth ratio were decreased, whereas crypt depth was increased in the jejunum at 7 and 14d after weaning. In addition, the mRNA levels of interferon-γ (IFN-γ), inducible nitric oxide synthase (iNOS), IL-6, IL-8, IL-12 and IL-22 were increased in the jejunum at 7 and 14d after weaning, whereas transforming growth factor-β (TGF-β), suppressor of cytokine signaling 3 (SCOS3) and arginase-1 was decreased. Neutrophil infiltration was increased in the mucosa of the jejunum after weaning. Moreover, phosphorylation of IκB-α, NF-κB, AKT and STAT-3 was increased. However, the phosphorylation of STAT-1 (at 7 and 14d) and STAT-6 (at 1 and 7d) was suppressed in the jejunum after weaning. Treatment of porcine jejunal epithelial (IPEC-J2) cells with the STAT inhibitors fludarabine, niclosamide and teriflunomide, which inhibit the phosphorylation of STAT-1, STAT-3 and STAT-6, respectively, weakened the defense capacity of these cells against bacterial infection. In conclusion, weaning caused severe inflammation associated with activation of the NF-κB and STAT-3 pathways and suppression of STAT-1 and STAT-6 in the jejunum of piglets.

Isolation and Expression Analysis of STAT Members from Synechogobius hasta and Their Roles in Leptin Affecting Lipid Metabolism

Signal transducers and activators of transcription proteins (STATs) act as important mediators in multiple biological processes induced by a large number of cytokines. In the present study, full-length cDNA sequences of seven STAT members, including some splicing variants different from those in mammals, were obtained from Synechogobius hasta. The phylogenetic analysis revealed that the seven STAT members were derived from paralogous genes that might have arisen by whole genome duplication (WGD) events during vertebrate evolution. All of these members share similar domain structure compared with those of mammals, and were widely expressed across the tested tissues (brain, gill, heart, intestine, liver, muscle and spleen), but at variable levels. Incubation in vitro of recombinant human leptin changed the intracellular triglyceride (TG) content and mRNA levels of several STATs members, as well as expressions and activities of genes involved in lipid metabolism. Furthermore, Tyrphostin B42 (AG490), a specific inhibitor of the Janus Kinase 2(JAK2)-STAT pathway, partially reversed leptin-induced change on STAT3 and its two spliced isoforms expression, as well as expressions and activities of genes involved in lipid metabolism. As a consequence, the decrease of TG content was also reversed. Thus, our study suggests that STAT3 is the requisite for the leptin signal and the activation of the STAT3 member may account for the leptin-induced changes in lipid metabolism in S. hasta.

Altered effector functions of NK cells in chronic hepatitis C are associated with IFNL3 polymorphism

Interferon α-mediated effector functions of NK cells may contribute to the control of HCV replication and the pathogenesis of liver disease. The single-nucleotide polymorphism rs12979860 near IFNL3 (previously known as IL28B) is important in response to IFN-α treatment and in spontaneous resolution of acute hepatitis C. The role of the IFNL3 polymorphism in NK cell function is unclear. Thus, we investigated the role of IFNL3 polymorphism in type I IFN-dependent regulation of NK cell functions in patients with cHC and healthy control subjects. We demonstrated a marked polarization of NK cells toward cytotoxicity in response to IFN-α stimulation in patients with hepatitis C. That TRAIL up-regulation was present, particularly in patients with the IFNL3-TT allele, was supported by a shift in the pSTAT-1:pSTAT-4 ratios toward pSTAT-1. In patients bearing the IFNL3-TT allele, NK cell effector function correlated with liver disease activity. In contrast, higher cytokine production of NK cells was observed in healthy individuals with the IFNL3-CC genotype, which may support spontaneous HCV clearance in acute infection. Overall, these findings show that the role of NK cells may differ in chronic infection vs. early antiviral defense and that the IFNL3 genotype differentially influences NK cell function.

Opposing roles of STAT1 and STAT3 in IL-21 function in CD4+ T cells

IL-21 is a type I cytokine essential for immune cell differentiation and function. Although IL-21 can activate several STAT family transcription factors, previous studies focused mainly on the role of STAT3 in IL-21 signaling. Here, we investigated the role of STAT1 and show that STAT1 and STAT3 have at least partially opposing roles in IL-21 signaling in CD4(+) T cells. IL-21 induced STAT1 phosphorylation, and this was augmented in Stat3-deficient CD4(+) T cells. RNA-Seq analysis of CD4(+) T cells from Stat1- and Stat3-deficient mice revealed that both STAT1 and STAT3 are critical for IL-21-mediated gene regulation. Expression of some genes, including Tbx21 and Ifng, was differentially regulated by STAT1 and STAT3. Moreover, opposing actions of STAT1 and STAT3 on IFN-γ expression in CD4(+) T cells were demonstrated in vivo during chronic lymphocytic choriomeningitis infection. Finally, IL-21-mediated induction of STAT1 phosphorylation, as well as IFNG and TBX21 expression, were higher in CD4(+) T cells from patients with autosomal dominant hyper-IgE syndrome, which is caused by STAT3 deficiency, as well as in cells from STAT1 gain-of-function patients. These data indicate an interplay between STAT1 and STAT3 in fine-tuning IL-21 actions.

Transcriptional and epigenetic regulation of T-helper lineage specification

Combined with TCR stimuli, extracellular cytokine signals initiate the differentiation of naive CD4⁺ T cells into specialized effector T-helper (Th) and regulatory T (Treg) cell subsets. The lineage specification and commitment process occurs through the combinatorial action of multiple transcription factors (TFs) and epigenetic mechanisms that drive lineage-specific gene expression programs. In this article, we review recent studies on the transcriptional and epigenetic regulation of distinct Th cell lineages. Moreover, we review current study linking immune disease-associated single-nucleotide polymorphisms with distal regulatory elements and their potential role in the disease etiology.

Involvement of Different networks in mammary gland involution after the pregnancy/lactation cycle: Implications in breast cancer

Early pregnancy is associated with a reduction in a woman's lifetime risk for breast cancer. However, different studies have demonstrated an increase in breast cancer risk in the years immediately following pregnancy. Early and long-term risk is even higher if the mother age is above 35 years at the time of first parity. The proinflammatory microenvironment within the mammary gland after pregnancy renders an "ideal niche" for oncogenic events. Signaling pathways involved in programmed cell death and tissue remodeling during involution are also activated in breast cancer. Herein, the major signaling pathways involved in mammary gland involution, signal transducer and activator of transcription (STAT3), nuclear factor-kappa B (NF-κB), transforming growth factor beta (TGFβ), and retinoid acid receptors (RARs)/retinoid X receptors (RXRs), are reviewed as part of the complex network of signaling pathways that crosstalk in a contextual-dependent manner. These factors, also involved in breast cancer development, are important regulatory nodes for signaling amplification after weaning. Indeed, during involution, p65/p300 target genes such as MMP9, Capn1, and Capn2 are upregulated. Elevated expression and activities of these proteases in breast cancer have been extensively documented. The role of these proteases during mammary gland involution is further discussed. MMPs, calpains, and cathepsins exert their effect by modification of the extracellular matrix and intracellular proteins. Calpains, activated in the mammary gland during involution, cleave several proteins located in cell membrane, lysosomes, mitochondria, and nuclei favoring cell death. Besides, during this period, Capn1 is most probably involved in the modulation of preadipocyte differentiation through chromatin remodeling. Calpains can be implicated in cell anchoring loss, providing a proper microenvironment for tumor growth. A better understanding of the role of any of these proteases in tumorigenesis may yield novel therapeutic targets or prognostic markers for breast cancer.

IL-6 blockade reverses the abnormal STAT activation of peripheral blood leukocytes from rheumatoid arthritis patients

Considering the interplay of multiple STATs in response to cytokines, we investigated how IL-6 and its blocking affect STAT signaling in rheumatoid arthritis (RA). Leukocytes obtained from RA patients before and after tocilizumab treatment and healthy donors (HDs) were cytokine-stimulated and STAT phosphorylation was analyzed by cytometry. RA patients had significantly fewer pSTAT1+, pSTAT3+, and pSTAT6+ monocytes and pSTAT5+ lymphocytes than HDs. After 24weeks of treatment, percentages of IFNγ-induced pSTAT1+ and IL-10-induced pSTAT3+ monocytes in RA patients increased, reaching levels comparable to HDs. pSTAT1+ and pSTAT3+ cells correlated inversely with RA disease activity index and levels of pSTAT+ cells at baseline were higher in patients with good EULAR response to tocilizumab. IFNγ-induced pSTAT1+ cells correlated inversely with memory T cells and anti-CCP levels. IL-10-induced pSTAT3+ cells correlated with Treg/Teff ratio. Our findings suggest that IL-6 blocking reduces the inflammatory mechanisms through the correction of STAT1 and STAT3 activation status.

ErbB targeting inhibitors repress cell migration of esophageal squamous cell carcinoma and adenocarcinoma cells by distinct signaling pathways

ErbB family receptor tyrosine kinases (ErbBs) play a role in cell adhesion and migration and are frequently overexpressed in esophageal squamous cell carcinomas (ESCCs) or esophageal adenocarcinomas (EACs). Targeting ErbBs by tyrosine kinase inhibitors (TKIs) may therefore limit esophageal cancer cell migration. Here, we studied the impact of TKIs on ErbB dimerization, cell signaling pathways, and cell migration in three esophageal cell lines: OE21 (ESCC), OE33 (EAC), and Het-1A (non-neoplastic esophageal epithelium). In OE21 cells, the TKIs erlotinib, gefitinib, and lapatinib slightly affected epidermal growth factor receptor EGFR/EGFR, but not EGFR/HER2 dimerization as detected by in situ proximity ligation assay (in situ PLA). Still, TKIs inhibited ERK1/2, Akt, STAT3, and RhoA activity in OE21 cells, as assessed by Western blot, antibody arrays, and Rho GTPase effector pull-down assays. This was accompanied by reduced OE21 cell migration, induction of focal adhesions, and actin cytoskeleton reorganization, as shown by Oris™ migration assay and focal adhesion kinase (FAK)/phalloidin staining. In contrast, in OE33 cells, only lapatinib decreased STAT5, Src family kinase (SFK), and FAK activity as well as β-catenin expression. This impeded cell migration and induced morphological changes in OE33 cells. No alterations were seen for the non-neoplastic Het-1A cells. Thus, we identified the ErbB signaling network as regulator of esophageal cancer cell's actin cytoskeleton, focal adhesions, and cell migration. ErbB targeted TKIs therefore also limit ESCC and EAC cell motility and migration.

KEY MESSAGE

Clinical tyrosine kinase inhibitors (TKIs) reduce esophageal cancer cell migration. Loss of cell migration is linked to reduced Akt, ERK1/2, STAT (3 or 5), FAK, SFKs, and RhoA activity. Clinical TKIs act via distinct signaling in the two main histotypes of esophageal cancer.