JAK/STAT signaling by cytokine receptors

Glycosylation: mechanisms, biological functions and clinical implications

Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.

STAT signaling pathways in immune cells and their associated mechanisms in cancer pathogenesis

Introduction

Signal transducer and activator of transcriptions (STATs) factors as critical proteins in cell signaling regulate diverse biological processes such as differentiation and proliferation of cells. STATs have been shown to play distinct roles in modulating immune responses mediated by innate and adaptive immune cell subsets due to their significant roles in cytokine signaling.

Methods

In the current study, we review recent studies on the contribution of individual STAT proteins to cytokine signaling, development, and activity of diverse immune cells that constitute the whole immune system and help its performance against endogenous or exogenous agents with a particular focus on meaningful STAT factor in each of innate and adaptive immune cells' subsets to clarify their function in favor of the tumor or against it.

Results

Dysregulation of signaling pathways in the immune cells is associated with various immune disorders, such as the inability of immune system cells in the effective destruction of cancerous cells. Increase of knowledge about these pathways' functions is essential to understand how they can be effectively targeted to eliminate tumors.

Conclusion

The majority of immune cells use the Jak/STAT signaling pathway, which is one of the most important signaling pathways with a role in induction of proper immune responses. Since each of the STAT factors has a specific role in diverse immune cells' subsets, appropriate targeting of them can be a promising strategy for patients who suffer from immune system disorders; specifically it can be beneficial as an approach for cancer immunotherapy.

Genome-wide identification of STATs and analysis of their role in sex determination in Pacific oysters (Crassostrea gigas)

STAT (signal transducer and activator of the transcription) proteins, are a group of highly conserved transcription factors and fundamental components of the JAK-STAT signaling pathway. They play crucial roles in a variety of biological processes, such as immunity, proliferation, differentiation, and growth. However, little information is known regarding their role in gonad development and sex determination in mollusks. In this study, we identified 3 STAT genes in Pacific Oyster Crassostrea gigas. Phylogenetic analysis showed that STATs from mollusks were highly conserved, and most of them had four identical motif regions, except for the STAT1 and STAT3 predicted sequences from Crassostrea hongkongensis. Tissue expression analysis indicated CgSTAT1 had a high expression level in most tissues, while CgSTAT3 had a low expression level in most tissues. Expression analysis of early developmental stages showed CgSTAT1 had a higher expression level from egg to D shaped larva and a lower expression level in subsequent stages. In contrast CgSTAT1, CgSTAT2 had a reverse expression pattern. Expression analysis of different developmental stages of diploid gonads indicated that CgSTAT1 had a higher expression level at the S1 and S3 stages relative to the S2 stage in females, while in males the S3 stage had a higher expression than than the S2 stage. The expression level of CgSTAT1 between diploids and triploids in females differed significantly, but there were no significant differences in males. Expression of CgSTAT2 differed significantly between diploid and triploid males. These data suggest an important role for STATs in sex differentiation in diploid and triploid oysters. Our study is the first to explore the role of STATs in sex differentiation and gonadal development in oysters, and will help us better understand the molecular mechanisms of sex differentiation in shellfish.

Drug Retention Rates of Janus Kinase Inhibitors in Rheumatoid Arthritis Patients with Therapy-Induced Lymphopenia

OBJECTIVES

To determine whether drug-induced lymphocytopenia is associated with drug retention rates of JAKi (tofacitinib or baricitinib) in rheumatoid arthritis (RA) patients.

METHODS

Patients with RA who were initiated with tofacitinib (n = 38) or baricitinib (n = 74) between July 2015 and July 2022 and continued for at least 4 months were enrolled in this study. Absolute lymphocyte count (ALC) value was obtained pre-treatment and monthly after initiation of JAKi (up to 4 months). Associations between ALC nadir at an early phase (up to 4 months) from JAKi initiation and drug retention rates were analysed.

RESULTS

112 patients (87 females; age, 71.2 ± 14.0 years; disease duration, 9.2 ± 10.5 months; DAS28-CRP, 3.60 ± 1.12; DAS28-ESR, 4.43 ± 1.29; CDAI, 17.9 ± 12.9; C-reactive protein, 3.07 ± 3.43 mg/dL; and lymphocyte count, 1361.9 ± 538.7 per μL) treated with tofacitinib or baricitinib were retrospectively analysed. Lymphocytopenia (>10% decline in lymphocyte count to pre-treatment basal levels) was observed in a quarter of RA patients treated with JAKi (tofacitinib; 16 baricitinib; 14). RA patients with lymphopenia were associated with the lower drug retention rates of tofacitinib compared to those without lymphocytopenia. The reduced drug retention rates in patients with lymphocytopenia were attributed to the discontinuation of tofacitinib due to AEs. Whereas lymphocytopenia was not associated with lower drug retention rates of baricitinib. Pre-treatment absolute lymphocyte counts did not affect the drug retention rates of JAKi in patients with RA.

CONCLUSIONS

These findings suggest that lymphopenia during the first 4 months from the initiation of JAKi is associated with reduced drug retention rates in patients with RA due to AEs, which is exclusively associated with the use of tofacitinib.

Targeted Therapies in Psoriatic Arthritis-An Update

Psoriatic arthritis (PsA) is a systemic inflammatory condition characterised by multiple clinical manifestations. Over the last decade, significant progress has been made in understanding the pathobiology of the disease. An expanded set of targeted therapies have emerged and have shown efficacy in PsA. Nevertheless, there is still a substantial subset of patients who experience no response or only a partial response to currently licensed therapies. The heterogeneous nature of the disease, together with a varying level of severity at presentation and disease activity during follow-up, brings tremendous challenges to devising management strategies. While there are certain pathophysiological similarities between PsA and rheumatoid arthritis (RA), it has become clear that there are discriminating features between these two conditions at the clinical, cellular, and molecular levels. However, there is a degree of overlap in the clinical approach when treating both PsA and RA, given that many biological and targeted therapies have proven efficacy for both pathologies. With an increasing understanding of the relevance of the IL-23/IL-17 axis in PsA, pharmacological agents blocking this pathway have provided promising possibilities for patients with PsA.

Are Janus kinase inhibitors safe and effective in treating the key clinical domains of psoriatic arthritis? A systematic review and meta-analysis

OBJECTIVES

Psoriatic arthritis (PsA), is a complex inflammatory arthropathy with a heterogenous spectrum of disease presentation. Despite the vast therapeutic armamentarium, disease control in a considerable proportion of patients is suboptimal. The aim of this study was to assess the safety and efficacy of Janus kinase inhibitors (JAKi), in the management of key clinical domains of PsA including peripheral arthritis, psoriasis, enthesitis and dactylitis.

METHOD

Randomized placebo-controlled trials (RCTs) of JAKi in PsA were identified by a systematic literature search using EMBASE, PubMed and CENTRAL. All included studies underwent meta-analysis.

RESULTS

A total of 5 RCTs were included. Patients were randomized to tofacitinib (n = 474), filgotinib (n = 65), upadacitinib (n = 1281) or placebo (n = 937). JAKi treatment was associated with superior efficacy across all primary outcome measures vs placebo: American College of Rheumatology (ACR) 20 (risk ratio [RR] 2.10, [95% CI 1.86-2.37], P < .00001, I2 = 19%); ACR 50 (RR 3.43, [95% CI 2.37-4.96], P < .00001, I2 = 66%); ACR 70 (RR 4.57, [95% CI 1.83-11.44], P = .001, I2 = 82%); Psoriasis Area and Severity Index 75 (RR 2.96, [95% CI 2.44-3.58], P < .00001, I2 = 0%); enthesitis resolution (RR 1.82, [95% CI 1.56-2.12], P < .00001, I2 = 0%); and dactylitis resolution (RR 1.85, [95% CI 1.57-2.16], P < .00001, I2 = 0%). JAKi were associated with an overall increased risk of adverse events (RR 1.14, [95% CI 1.07-1.21], P = .0001, I2 = 0%) with increased risk of infection (RR1.23, [95% CI 1.08-1.39], P = .001, I2 = 0%) vs placebo.

CONCLUSION

This pooled analysis demonstrates the efficacy of JAKi in treating key clinical domains of PsA. However, they are associated with an increased risk of adverse events, including infection. Further studies are required to corroborate these findings and further elucidate the safety profile.

Inhibition of the JAK2/STAT3 pathway and cell cycle re-entry contribute to the protective effect of remote ischemic pre-conditioning of rat hindlimbs on cerebral ischemia/reperfusion injury

AIMS

Remote ischemic pre-conditioning (RIPC) protects against ischemia/reperfusion (I/R) injury. However, the mechanisms underlying this protection remain unclear. In the present study, we investigated the role of Janus-activated kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway and cell cycle arrest, and their relationship with neuronal apoptosis following RIPC.

METHODS

A rat cerebral I/R injury model was induced by middle cerebral artery occlusion (MCAO), and AG490 was used to investigate the mechanisms of RIPC. p-JAK2-, p-STAT3-, cyclin D1-, and cyclin-dependent kinase 6 (CDK6) expression was assessed by Western blotting and immunofluorescence staining.

RESULTS

RIPC reduced the infarct volume, improved neurological function, and increased neuronal survival. Furthermore, p-JAK2 and p-STAT3 were detected during the initial phase of reperfusion; the expression levels were significantly increased at 3 and 24 h after reperfusion and were suppressed by RIPC. Additionally, the MCAO-induced upregulation of the cell cycle regulators cyclin D1 and CDK6 was ameliorated by RIPC. Meanwhile, cyclin D1 and CDK6 were colocalized with p-STAT3 in the ischemic brain.

CONCLUSION

RIPC ameliorates the induction of the JAK2/STAT3 pathway and cell cycle regulators cyclin D1 and CDK6 by MCAO, and this net inhibition of cell cycle re-entry by RIPC is associated with downregulation of STAT3 phosphorylation.

STAT family of transcription factors in breast cancer: Pathogenesis and therapeutic opportunities and challenges

Breast cancer is the most commonly diagnosed cancer and second-leading cause of cancer deaths in women. Breast cancer stem cells (BCSCs) promote metastasis and therapeutic resistance contributing to tumor relapse. Through activating genes important for BCSCs, transcription factors contribute to breast cancer metastasis and therapeutic resistance, including the signal transducer and activator of transcription (STAT) family of transcription factors. The STAT family consists of six major isoforms, STAT1, STAT2, STAT3, STAT4, STAT5, and STAT6. Canonical STAT signaling is activated by the binding of an extracellular ligand to a cell-surface receptor followed by STAT phosphorylation, leading to STAT nuclear translocation and transactivation of target genes. It is important to note that STAT transcription factors exhibit diverse effects in breast cancer; some are either pro- or anti-tumorigenic while others maintain dual, context-dependent roles. Among the STAT transcription factors, STAT3 is the most widely studied STAT protein in breast cancer for its critical roles in promoting BCSCs, breast cancer cell proliferation, invasion, angiogenesis, metastasis, and immune evasion. Consequently, there have been substantial efforts in developing cancer therapeutics to target breast cancer with dysregulated STAT3 signaling. In this comprehensive review, we will summarize the diverse roles that each STAT family member plays in breast cancer pathobiology, as well as, the opportunities and challenges in pharmacologically targeting STAT proteins and their upstream activators in the context of breast cancer treatment.

Induction of T cell exhaustion by JAK1/3 inhibition in the treatment of alopecia areata

Alopecia areata (AA) is an autoimmune disease caused by T cell-mediated destruction of the hair follicle (HF). Therefore, approaches that effectively disrupt pathogenic T cell responses are predicted to have therapeutic benefit for AA treatment. T cells rely on the duality of T cell receptor (TCR) and gamma chain (γc) cytokine signaling for their development, activation, and peripheral homeostasis. Ifidancitinib is a potent and selective next-generation JAK1/3 inhibitor predicted to disrupt γc cytokine signaling. We found that Ifidancitinib robustly induced hair regrowth in AA-affected C3H/HeJ mice when fed with Ifidancitinib in chow diets. Skin taken from Ifidancitinib-treated mice showed significantly decreased AA-associated inflammation. CD44⁺CD62L^- CD8⁺ T effector/memory cells, which are associated with the pathogenesis of AA, were significantly decreased in the peripheral lymphoid organs in Ifidancitinib-treated mice. We observed high expression of co-inhibitory receptors PD-1 on effector/memory CD8⁺ T cells, together with decreased IFN-γ production in Ifidancitinib-treated mice. Furthermore, we found that γc cytokines regulated T cell exhaustion. Taken together, our data indicate that selective induction of T cell exhaustion using a JAK inhibitor may offer a mechanistic explanation for the success of this treatment strategy in the reversal of autoimmune diseases such as AA.

LncRNA HOTTIP from synovial fibroblast-derived exosomes: A novel molecular target for rheumatoid arthritis through the miR-1908-5p/STAT3 axis

Rheumatoid arthritis (RA) is a chronic inflammation mediated by autoimmune responses. HOTTIP, a long noncoding RNA (lncRNA), participates in cell proliferation and invasion. However, the correlation between HOTTIP and RA remains unclear. Therefore, this study aimed to clarify how HOTTIP works in RA and to investigate its role in the development of RA. Flow cytometry was used to analyze cell cycle progression. Binding between HOTTIP, signal transducer and activator of transcription 3 (STAT3) and miR-1908-5p was demonstrated by dual-luciferase assays. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure the expression of T cell differentiation-related proteins. We found that HOTTIP was upregulated in rheumatoid arthritis synovial fibroblasts (RASFs). HOTTIP directly bound to miR-1908-5p and negatively modulated miR-1908-5p expression while positively regulating STAT3. The effects of HOTTIP overexpression on regulating the balance of the Th17/Treg cell ratio were partly reversed by miR-1908-5p overexpression. In addition, in vivo experiments demonstrated that overexpression of HOTTIP aggravated inflammation in RA mice, which was demonstrated by hematoxylin and eosin (HE) staining and the increased expression levels of CD4⁺ interleukin (IL)-17⁺, forkhead Box P3 (FOXP3) and retinoid-related orphan receptor gamma-t (RORγt). In summary, our study suggests that HOTTIP plays a damaging role in RA by promoting inflammation, which may be related to the regulation of miR-1908-5p expression and the STAT3 signaling pathway. These results suggest that the regulation of HOTTIP may be a promising therapeutic strategy for RA.

STAT proteins: a kaleidoscope of canonical and non-canonical functions in immunity and cancer

STAT proteins represent an important family of evolutionarily conserved transcription factors that play key roles in diverse biological processes, notably including blood and immune cell development and function. Classically, STAT proteins have been viewed as inducible activators of transcription that mediate cellular responses to extracellular signals, particularly cytokines. In this 'canonical' paradigm, latent STAT proteins become tyrosine phosphorylated following receptor activation, typically via downstream JAK proteins, facilitating their dimerization and translocation into the nucleus where they bind to specific sequences in the regulatory region of target genes to activate transcription. However, growing evidence has challenged this paradigm and identified alternate 'non-canonical' functions, such as transcriptional repression and roles outside the nucleus, with both phosphorylated and unphosphorylated STATs involved. This review provides a revised framework for understanding the diverse kaleidoscope of STAT protein functional modalities. It further discusses the implications of this framework for our understanding of STAT proteins in normal blood and immune cell biology and diseases such as cancer, and also provides an evolutionary context to place the origins of these alternative functional modalities.

JAK2 deficiency improves erectile function in diabetic mice through attenuation of oxidative stress, apoptosis, and fibrosis

Background

Janus kinase 2 (JAK2) is activated in diabetic mellitus (DM) conditions and may enhance oxidative stress, apoptosis and fibrosis in many tissues. Whether JAK2 activation is involved in the occurrence of diabetic erectile dysfunction (ED) is unknown.

Objectives

We performed this study to investigate the effect of JAK2 deficiency on diabetic ED.

Materials and methods

Conditional JAK2 gene knockout mice (Cre^+/+‐JAK2^fl/fl) were used, in which JAK2 gene knockout could be induced by tamoxifen. Mice fell into four groups: control, JAK2 knockout (JAK2^−/−), DM, and DM with JAK2^−/−. DM was induced by intraperitoneal injection of streptozotocin. Two months later, JAK2 gene knockout was induced with tamoxifen in Cre^+/+‐JAK2^fl/fl mice. After another 2 months, erectile function was measured by electrical stimulation of the cavernous nerve, and penile tissues were harvested. Ratio of maximal intracavernosal pressure (MIP) to mean arterial blood pressure (MAP), expression and phosphorylation of JAK2, oxidative stress level, NO/Cyclic Guanosine Monophosphate (cGMP) pathway, apoptosis, fibrosis, and transforming growth factor beta 1 (TGF‐β1)/Smad/Collagen IV pathway in corpus cavernosum, were measured.

Results

JAK2 expression was remarkably decreased after induction with tamoxifen. JAK2 was activated in penile tissues of diabetic mice, and JAK2 deficiency could improve the impaired erectile function caused by DM. However, in mice without DM, JAK2 deficiency had no apparent influence on erectile function. Levels of oxidative stress, apoptosis, fibrosis, and TGF‐β1/Smad/Collagen IV pathway were all elevated by DM, whereas JAK2 deficiency lessened these alterations in diabetic mice. Moreover, JAK2 deficiency improved the expression of the down‐regulated NO/cGMP pathway in diabetic mice. In non‐diabetic mice, no apparent changes were found in aforementioned parameters after JAK2 gene knockout.

Discussion and conclusion

Our study showed that JAK2 deficiency could improve erectile function in diabetic mice, which might be mediated by reduction in oxidative stress, apoptosis, and fibrosis in corpus cavernosum.

Transient prenatal ruxolitinib treatment suppresses astrogenesis during development and improves learning and memory in adult mice

Ruxolitinib is the first janus kinase 1 (JAK1) and JAK2 inhibitor that was approved by the United States Food and Drug Administration (FDA) agency for the treatment of myeloproliferative neoplasms. The drug targets the JAK/STAT signalling pathway, which is critical in regulating the gliogenesis process during nervous system development. In the study, we assessed the effect of non-maternal toxic dosages of ruxolitinib (0-30 mg/kg/day between E7.5-E20.5) on the brain of the developing mouse embryos. While the pregnant mice did not show any apparent adverse effects, the Gfap protein marker for glial cells and S100β mRNA marker for astrocytes were reduced in the postnatal day (P) 1.5 pups' brains. Gfap expression and Gfap+ cells were also suppressed in the differentiating neurospheres culture treated with ruxolitinib. Compared to the control group, adult mice treated with ruxolitinib prenatally showed no changes in motor coordination, locomotor function, and recognition memory. However, increased explorative behaviour within an open field and improved spatial learning and long-term memory retention were observed in the treated group. We demonstrated transplacental effects of ruxolitinib on astrogenesis, suggesting the potential use of ruxolitinib to revert pathological conditions caused by gliogenic-shift in early brain development such as Down and Noonan syndromes.

AG490 protects cerebral ischemia/reperfusion injury via inhibiting the JAK2/3 signaling pathway

BACKGROUND

Cerebral ischemia/reperfusion injury is a severe problem in patients with brain ischemia. Brain injury caused by the immune response is important in the pathogenesis of cerebral ischemia/reperfusion injury and immune pathways. It is important to investigate potential targets for the treatment of cerebral ischemia/reperfusion injury.

METHODS

In this experiment, we evaluated the effect of an exogenous JAK antagonist AG490 in the cerebral ischemia/reperfusion injury model, which was established by middle cerebral artery occlusion (MCAO). Histology study, TUNEL staining, Western blot, and RT-PCR were employed to examine the effects of AG490 in cerebral ischemia/reperfusion injury.

RESULTS

In the brain tissue of MCAO mice, JAK2 was highly expressed. AG490 is an inhibitor of JAK2, which reduced the phosphorylation level of JAK2. AG490 downregulated the phosphorylated activation of JAK3 and their downstream STAT3. The antiapoptotic activity of AG490 on cerebral ischemia/reperfusion injury mice was consistent with in vitro data. It reduced the phosphorylation of JAK2/JAK3/STAT3 and the apoptosis rate in cultured neurons upon apoptosis induction. Besides, we also observed the neuroprotective effects of AG490 on cerebral ischemia/reperfusion injury. Administration of AG490 could further enhance the expression of neurotrophins including BNDF, NT3, and the neurotrophin receptor TrkB.

CONCLUSION

Therefore, AG490 is pluripotent for cerebral ischemia/reperfusion injury through both antiapoptosis and neuroprotective activities. The antiapoptosis effect is dependent on its regulation of the JAK-STAT pathway.

Baricitinib: A Review of Pharmacology, Safety, and Emerging Clinical Experience in COVID-19

A hyperinflammatory response to severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) infection, reminiscent of cytokine release syndrome, has been implicated in the pathophysiology of acute respiratory distress syndrome and organ damage in patients with coronavirus disease 2019 (COVID-19). Agents that inhibit components of the pro-inflammatory cascade have garnered interest as potential treatment options with hopes that dampening the proinflammatory process may improve clinical outcomes. Baricitinib is a reversible Janus-associated kinase (JAK)-inhibitor that interrupts the signaling of multiple cytokines implicated in COVID-19 immunopathology. It may also have antiviral effects by targeting host factors that viruses rely for cell entry and by suppressing type I interferon driven angiotensin-converting-enzyme-2 upregulation. However, baricitinib's immunosuppressive effects may be detrimental during acute viral infections by delaying viral clearance and increasing vulnerability to secondary opportunistic infections. The lack of reliable biomarkers to monitor patients' immune status as illness evolves complicates deployment of immunosuppressive drugs like baricitinib. Furthermore, baricitinib carries the risk of increased thromboembolic events, which is concerning given the proclivity towards a hypercoagulable state in patients with COVID-19. In this article, we review available data on baricitinib with an emphasis on immunosuppressive and antiviral pharmacology, pharmacokinetics, safety, and current progress in COVID-19 clinical trials.

Regulation of autoimmune arthritis by the SHP-1 tyrosine phosphatase

Background

The Src homology region 2 domain-containing phosphatase-1 (SHP-1) is known to exert negative regulatory effects on immune cell signaling. Mice with mutations in the Shp1 gene develop inflammatory skin disease and autoimmunity, but no arthritis.

We sought to explore the role of SHP-1 in arthritis using an autoimmune mouse model of rheumatoid arthritis. We generated Shp1 transgenic (Shp1-Tg) mice to study the impact of SHP-1 overexpression on arthritis susceptibility and adaptive immune responses.

Methods

SHP-1 gene and protein expression as well as tyrosine phosphatase activity were evaluated in spleen cells of transgenic and wild type (WT) mice. WT and Shp1-Tg (homozygous or heterozygous for the transgene) mice were immunized with human cartilage proteoglycan (PG) in adjuvant, and arthritis symptoms were monitored. Protein tyrosine phosphorylation level, net cytokine secretion, and serum anti-human PG antibody titers were measured in immune cells from WT and Shp1-Tg mice. WT mice were treated with regorafenib orally to activate SHP-1 either before PG-induced arthritis (PGIA) symptoms developed (preventive treatment) or starting at an early stage of disease (therapeutic treatment). Data were statistically analyzed and graphs created using GraphPad Prism 8.0.2 software.

Results

SHP-1 expression and tyrosine phosphatase activity were elevated in both transgenic lines compared to WT mice. While all WT mice developed arthritis after immunization, none of the homozygous Shp1-Tg mice developed the disease. Heterozygous transgenic mice, which showed intermediate PGIA incidence, were selected for further investigation. We observed differences in interleukin-4 and interleukin-10 production in vitro, but serum anti-PG antibody levels were not different between the genotypes. We also found decreased tyrosine phosphorylation of several proteins of the JAK/STAT pathway in T cells from PG-immunized Shp1-Tg mice. Regorafenib administration to WT mice prevented the development of severe PGIA or reduced disease severity when started after disease onset.

Conclusions

Resistance to arthritis in the presence of SHP-1 overexpression likely results from the impairment of tyrosine phosphorylation (deactivation) of key immune cell signaling proteins in the JAK/STAT pathway, due to the overwhelming tyrosine phosphatase activity of the enzyme in Shp1-Tg mice. Our study is the first to investigate the role of SHP-1 in autoimmune arthritis using animals overexpressing this phosphatase. Pharmacological activation of SHP-1 might be considered as a new approach to the treatment of autoimmune arthritis.

gga-miR-27b-3p enhances type I interferon expression and suppresses infectious bursal disease virus replication via targeting cellular suppressors of cytokine signaling 3 and 6 (SOCS3 and 6)

MicroRNAs are small noncoding RNAs playing an important role in host response to pathogenic infection. Here we show that IBDV infection induced the demethylation of the pre-miR-27 promoter and upregulated gga-miR-27b-3p expression. We found that ectopic expression of miR-27b-3p in DF-1 cells enhanced the expression of chicken IFN-β, IRF3 and NF-κB, via directly targeting cellular suppressors of cytokine signaling 3 and 6 (SOCS3 and 6), inhibiting IBDV replication in host cells, while inhibition of endogenous miR-27b-3p by its inhibitors suppressed the expression of IFN-β, IRF3 and NF-κB, enhancing SOCS3 and 6 expressions and facilitating IBDV replication. Furthermore, transfection of DF-1 cells with miR-27b-3p markedly increased phosphorylation of STAT1 on Tyr701 in cells post chIFN-γ treatment. On the contrary, inhibition of endogenous miR-27b-3p reduced phosphorylation of STAT1 on Tyr701 in cells with chIFN-γ treatment. These findings indicate that gga-miR-27b-3p serves as an inducible antiviral mediator in host response to IBDV infection.

3-Deoxy-2β,16-dihydroxynagilactone E, a natural compound from Podocarpus nagi, preferentially inhibits JAK2/STAT3 signaling by allosterically interacting with the regulatory domain of JAK2 and induces apoptosis of cancer cells

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathways, especially the JAK2/STAT3 pathway, play vital roles in the development of many malignancies. Overactivation of STAT3 promotes cancer cell survival and proliferation. Therefore, the JAK2/STAT3-signaling pathway has been considered a promising target for cancer therapy. In this study, we identified a natural compound 3-deoxy-2β,16-dihydroxynagilactone E (B6) from the traditional Chinese medicinal plant Podocarpus nagi as a potent inhibitor of STAT3 signaling. B6 preferentially inhibited the phosphorylation of STAT3 by interacting with and inactivating JAK2, the main upstream kinase of STAT3. B6 dose-dependently inhibited IL-6-induced STAT3 signaling with an IC₅₀ of 0.2 μM. In contrast to other JAK2 inhibitors, B6 did not interact with the catalytic domain but instead with the FERM-SH2 domain of JAK2. This interaction was JAK-specific since B6 had little effect on other tyrosine kinases. Furthermore, B6 potently inhibited the growth and induced apoptosis of MDA-MB-231 and MDA-MB-468 breast cancer cells with overactivated STAT3. Taken together, our study uncovers a novel compound and a novel mechanism for the regulation of JAK2 and offers a new therapeutic approach for the treatment of cancers with overactivated JAK2/STAT3.

E2F is required for STAT3-mediated upregulation of cyclin B1 and Cdc2 expressions and contributes to G2-M phase transition

Activation of transcription factor STAT3 is involved in cell proliferation, differentiation, and cell survival. Constitutive activation of STAT3 pathway has been associated with the oncogenesis of various types of cancers. It has been reported that STAT3 plays a key role in the G1 to S phase cell cycle transition induced by the cytokine receptor subunit gp130, through the upregulation of cyclins D1, D2, D3, A, and Cdc25A and the concomitant downregulation of p21 and p27. However, its role in mediating G2-M phase transition has not been studied. The cyclin B1/Cdc2 complex is widely accepted as the trigger of mitosis in all organisms and is believed to be necessary for progression through S phase and keep active during the G2-M transition and progression. In the present study, we found that activation of STAT3 stimulates cyclin B1 and Cdc2 expressions. Deletion and site-directed mutations on cyclin B1 and Cdc2 promoters indicated that E2F element mediates the upregulation of these two promoters in a STAT3-dependent manner. The findings reported here demonstrated that STAT3 participates in modulating G2-M phase checkpoint by regulating gene expressions of cyclin B1 and Cdc2 via E2F.

Molecular Pathogenesis of Myeloproliferative Neoplasms: Influence of Age and Gender

The myeloproliferative neoplasms polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) display distinct clinical and pathologic features but are characterized by mutations in JAK2, MPL, and CALR leading to activation of the JAK-STAT pathway. This review addresses the pathogenesis and mechanisms of these mutant alleles and the unique interactions of both of age and gender.

MicroRNA gga-miR-130b Suppresses Infectious Bursal Disease Virus Replication via Targeting of the Viral Genome and Cellular Suppressors of Cytokine Signaling 5

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression posttranscriptionally through silencing or degrading their targets, thus playing important roles in the immune response. However, the role of miRNAs in the host response against infectious bursal disease virus (IBDV) infection is not clear. In this study, we show that the expression of a series of miRNAs was significantly altered in DF-1 cells after IBDV infection. We found that the miRNA gga-miR-130b inhibited IBDV replication via targeting the specific sequence of IBDV segment A and enhanced the expression of beta interferon (IFN-β) by targeting suppressors of cytokine signaling 5 (SOCS5) in host cells. These findings indicate that gga-miR-130b-3p plays a crucial role in host defense against IBDV infection.IMPORTANCE This work shows that gga-miR-130b suppresses IBDV replication via directly targeting the viral genome and cellular SOCS5, the negative regulator for type I interferon expression, revealing the mechanism underlying gga-miR-130-induced inhibition of IBDV replication. This information will be helpful for the understanding of how host cells combat pathogenic infection by self-encoded small RNA and furthers our knowledge of the role of microRNAs in the cell response to viral infection.

Improving Gene Regulatory Network Inference by Incorporating Rates of Transcriptional Changes

Organisms respond to changes in their environment through transcriptional regulatory networks (TRNs). The regulatory hierarchy of these networks can be inferred from expression data. Computational approaches to identify TRNs can be applied in any species where quality RNA can be acquired, However, ChIP-Seq and similar validation methods are challenging to employ in non-model species. Improving the accuracy of computational inference methods can significantly reduce the cost and time of subsequent validation experiments. We have developed ExRANGES, an approach that improves the ability to computationally infer TRN from time series expression data. ExRANGES utilizes both the rate of change in expression and the absolute expression level to identify TRN connections. We evaluated ExRANGES in five data sets from different model systems. ExRANGES improved the identification of experimentally validated transcription factor targets for all species tested, even in unevenly spaced and sparse data sets. This improved ability to predict known regulator-target relationships enhances the utility of network inference approaches in non-model species where experimental validation is challenging. We integrated ExRANGES with two different network construction approaches and it has been implemented as an R package available here: http://github.com/DohertyLab/ExRANGES. To install the package type: devtools::install_github(“DohertyLab/ExRANGES”).

Anti-leukaemic activity of the TYK2 selective inhibitor NDI-031301 in T-cell acute lymphoblastic leukaemia

Activation of tyrosine kinase 2 (TYK2) contributes to the aberrant survival of T-cell acute lymphoblastic leukaemia (T-ALL) cells. Here we demonstrate the anti-leukaemic activity of a novel TYK2 inhibitor, NDI-031301. NDI-031301 is a potent and selective inhibitor of TYK2 that induced robust growth inhibition of human T-ALL cell lines. NDI-031301 treatment of human T-ALL cell lines resulted in induction of apoptosis that was not observed with the JAK inhibitors tofacitinib and baricitinib. Further investigation revealed that NDI-031301 treatment uniquely leads to activation of three mitogen-activated protein kinases (MAPKs), resulting in phosphorylation of ERK, SAPK/JNK and p38 MAPK coincident with PARP cleavage. Activation of p38 MAPK occurred within 1 h of NDI-031301 treatment and was responsible for NDI-031301-induced T-ALL cell death, as pharmacological inhibition of p38 MAPK partially rescued apoptosis induced by TYK2 inhibitor. Finally, daily oral administration of NDI-031301 at 100 mg/kg bid to immunodeficient mice engrafted with KOPT-K1 T-ALL cells was well tolerated, and led to decreased tumour burden and a significant survival benefit. These results support selective inhibition of TYK2 as a promising potential therapeutic strategy for T-ALL.

S-nitrosocaptopril interrupts adhesion of cancer cells to vascular endothelium by suppressing cell adhesion molecules via inhibition of the NF-кB and JAK/STAT signal pathways in endothelial cells

Inflammatory cytokines can induce the expression of cell adhesion molecules (CAMs) in endothelial cells. The induction may play an important role in attracting circulating tumor cells (CTCs) to endothelial cells. S-nitrosocaptopril (CapNO) is known to produce vasorelaxation and interfere the hetero-adhesion of CTCs to vascular endothelium via down-regulating the expression of CAMs. To elucidate the mechanisms underlying the inhibition of CapNO on CAMs, in this study, we examined the relationship between cytokines and CAMs expression and investigated the effects of CapNO on cytokine-induced NF-кB and JAK/STAT signal pathways. The activation of CAMs by cytokines was dependent on concentrations and reaction time of cytokines, and the combination of cytokines could produce a strong synergistic effect. IL-1β induced the expression of CAMs on endothelial cells by activating NF-кB and JAK/STAT pathways. CapNO inhibited IL-1β-stimulated NF-кB pathway by down-regulating IKK-α and inducing IкB-α directly. CapNO also inhibited JAK/STAT pathway by inhibiting JAK2 and STAT3 expressions. These effects bring about down-regulating CAMs expression on endothelial cells. These results suggest that CapNO may interrupt adhesion of cancer cells to endothelium by suppressing CAMs via inhibiting the NF-кB and JAK/STAT pathways in endothelial cells.

Brain-derived neurotrophic factor promotes nerve regeneration by activating the JAK/STAT pathway in Schwann cells

Background

Radical prostatectomy (RP) carries the risk of erectile dysfunction (ED) due to cavernous nerve (CN) injury. Schwann cells are essential for the maintenance of integrity and function of peripheral nerves such as the CNs. We hypothesize that brain-derived neurotrophic factor (BDNF) activates the Janus kinase (JAK)/(signal transducer and activator of transcription) STAT pathway in Schwann cells, not in neuronal axonal fibers, with the resultant secretion of cytokines from Schwann cells to facilitate nerve recovery.

Methods

Using four different cell lines—human neuroblastoma BE(2)-C and SH-SY5Y, human Schwann cell (HSC), and rat Schwann cell (RSC) RT4-D6P2T—we assessed the effect of BDNF application on the activation of the JAK/STAT pathway. We also assessed the time response of JAK/STAT pathway activation in RSCs and HSCs after BDNF treatment. We then assayed cytokine release from HSCs as a response to BDNF treatment using oncostatin M and IL6 as markers.

Results

We showed extensive phosphorylation of STAT3/STAT1 by BDNF at high dose (100 pM) in RSCs, with no JAK/STAT pathway activation in human neuroblastoma cell lines. The time response of JAK/STAT pathway activation in RSCs and HSCs after BDNF treatment showed an initial peak at shortly after treatment and then a second higher peak at 24–48 hours. Cytokine release from HSCs increased progressively after BDNF application, reaching statistical significance for IL6.

Conclusions

We demonstrated for the first time the indirect mechanism of BDNF enhancement of nerve regeneration through the activation of JAK/STAT pathway in Schwann cells, rather than directly on neurons. As a result of BDNF application, Schwann cells produce cytokines that promote nerve regeneration.

Intestine immune homeostasis after alcohol and burn injury

Traumatic injury remains one of the most prevalent reasons for patients to be hospitalized. Burn injury accounts for 40,000 hospitalizations in the United States annually, resulting in a large burden on both the health and economic system and costing millions of dollars every year. The complications associated with postburn care can quickly cause life-threatening conditions including sepsis and multiple organ dysfunction and failure. In addition, alcohol intoxication at the time of burn injury has been shown to exacerbate these problems. One of the biggest reasons for the onset of these complications is the global suppression of the host immune system and increased susceptibility to infection. It has been hypothesized that infections after burn and other traumatic injury may stem from pathogenic bacteria from within the host's gastrointestinal tract. The intestine is the major reservoir of bacteria within the host, and many studies have demonstrated perturbations of the intestinal barrier after burn injury. This article reviews the findings of these studies as they pertain to changes in the intestinal immune system after alcohol and burn injury.

Molecular basis for cytokine biomarkers of complex 3D microtissue physiology in vitro

'Physiologically more-relevant' claims are readily made for cells cultured on any surface or in a scaffold that provides loosely defined 3D geometry. A set of tools to measure culture '3D-ness' more accurately are needed. Such tools should find applications in fields ranging from high-throughput identification of substrates for tissue engineering and regenerative medicine to cell-based screening of drug candidates. Until now, these fields have not provided a consensus for the most promising place to initiate the search. Here, we review recent advances in transcriptomic, proteomic, inflammation and oncology-related pathways, as well as functional studies that strongly point to cytokines as the most likely compounds to form the missing consensus.

Potential Role of JAK-STAT Signaling Pathway in the Neurogenic-to-Gliogenic Shift in Down Syndrome Brain

Trisomy of human chromosome 21 in Down syndrome (DS) leads to several phenotypes, such as mild-to-severe intellectual disability, hypotonia, and craniofacial dysmorphisms. These are fundamental hallmarks of the disorder that affect the quality of life of most individuals with DS. Proper brain development involves meticulous regulation of various signaling pathways, and dysregulation may result in abnormal neurodevelopment. DS brain is characterized by an increased number of astrocytes with reduced number of neurons. In mouse models for DS, the pool of neural progenitor cells commits to glia rather than neuronal cell fate in the DS brain. However, the mechanism(s) and consequences of this slight neurogenic-to-gliogenic shift in DS brain are still poorly understood. To date, Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling has been proposed to be crucial in various developmental pathways, especially in promoting astrogliogenesis. Since both human and mouse models of DS brain exhibit less neurons and a higher percentage of cells with astrocytic phenotypes, understanding the role of JAK-STAT signaling in DS brain development will provide novel insight into its role in the pathogenesis of DS brain and may serve as a potential target for the development of effective therapy to improve DS cognition.

Myeloproliferative neoplasms: Current molecular biology and genetics

Myeloproliferative neoplasms (MPNs) are clonal disorders characterized by increased production of mature blood cells. Philadelphia chromosome-negative MPNs (Ph-MPNs) consist of polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). A number of stem cell derived mutations have been identified in the past 10 years. These findings showed that JAK2V617F, as a diagnostic marker involving JAK2 exon 14 with a high frequency, is the best molecular characterization of Ph-MPNs. Somatic mutations in an endoplasmic reticulum chaperone, named calreticulin (CALR), is the second most common mutation in patients with ET and PMF after JAK2 V617F mutation. Discovery of CALR mutations led to the increased molecular diagnostic of ET and PMF up to 90%. It has been shown that JAK2V617F is not the unique event in disease pathogenesis. Some other genes' location such as TET oncogene family member 2 (TET2), additional sex combs-like 1 (ASXL1), casitas B-lineage lymphoma proto-oncogene (CBL), isocitrate dehydrogenase 1/2 (IDH1/IDH2), IKAROS family zinc finger 1 (IKZF1), DNA methyltransferase 3A (DNMT3A), suppressor of cytokine signaling (SOCS), enhancer of zeste homolog 2 (EZH2), tumor protein p53 (TP53), runt-related transcription factor 1 (RUNX1) and high mobility group AT-hook 2 (HMGA2) have also identified to be involved in MPNs phenotypes. Here, current molecular biology and genetic mechanisms involved in MNPs with a focus on the aforementioned factors is presented.

Immune responses of porcine airway epithelial cells to poly(I:C), a synthetic analogue of viral double-stranded RNA

Yang, X.-q., Wang, L., Li, H.-t. and Liu, D. 2015. Immune responses of porcine airway epithelial cells to poly(I:C), a synthetic analogue of viral double-stranded RNA. Can. J. Anim. Sci. 95: 13–20. Swine respiratory disease (SRD) is one of the most economically important diseases affecting the pig industry. The main infectious agents that cause SRD are viruses, but the molecular pathogenesis of viral SRD has not been extensively studied. Here, using digital gene expression tag profiling, the global transcriptional responses to poly(I:C), a synthetic analogue of viral double-stranded RNA, was analyzed in porcine airway epithelial cells (PAECs). The profiling analysis revealed numerous differentially expressed genes (DEGs), including unknown sequences in the porcine nucleotide databases. Gene ontology enrichment analysis showed that DEGs were mainly enriched in response to stress (GO: 0006950), of which, defense response is one sub-process. Poly(I:C) challenge induced a general inflammation response as indicated by marked upregulation of a variety of pathogen recognition receptors, interferon-stimulated genes, proinflammatory cytokines, and chemokines, together with the significant downregulation of anti-inflammatory molecules. Furthermore, the antiapoptotic pathway was triggered, as demonstrated by the significant suppression of molecules involved in the induction of apoptosis, together with the significant stimulation of putative inhibitor of apoptosis. The results indicate that PAECs initiated defense against poly(I:C) challenge through the inflammation responses, whereas poly(I:C) can utilize antiapoptotic pathway to evade host defense.

Contribution of chaperones to STAT pathway signaling

Aberrant STAT signaling is associated with the development and progression of many cancers and immune related diseases. Recent findings demonstrate that proteostasis modulators under clinical investigation for cancer therapy have a significant impact on STAT signaling, which may be critical for mediating their anti-cancer effects. Chaperones are critical for protein folding, stability and function and, thus, play an essential role in the maintenance of proteostasis. In this review we discuss the role of chaperones in STAT and tyrosine kinase (TK) protein folding, modulation of STAT and TK activity, and degradation of TKs. We highlight the important role of chaperones in STAT signaling, and how this knowledge has provided a framework for the development of new therapeutic avenues of targeting STAT signaling related pathologies.

Modulation of apoptosis-related cell signalling pathways by curcumin as a strategy to inhibit tumor progression

A hallmark of cancer is resistance to apoptosis, with both the loss of proapoptotic signals and the gain of anti-apoptotic mechanisms contributing to tumorigenesis. As inducing apoptosis in malignant cells is one of the most challenging tasks regarding cancer, researchers increasingly focus on natural products to regulate apoptotic signaling pathways. Curcumin, a polyphenolic derivative of turmeric, is a natural compound derived from Curcuma longa, has attracted great interest in the research of cancer during the last half century. Extensive studies revealed that curcumin has chemopreventive properties, which are mainly due to its ability to arrest cell cycle and to induce apoptosis in cancer cells either alone or in combination with chemotherapeutic agents or radiation. The underlying action mechanisms of curcumin are diverse and has not been elucidated so far. By regulating multiple important cellular signalling pathways including NF-κB, TRAIL, PI3 K/Akt, JAK/STAT, Notch-1, JNK, etc., curcumin are known to activate cell death signals and induce apoptosis in pre-cancerous or cancer cells without affecting normal cells, thereby inhibiting tumor progression. Several phase I and phase II clinical trials indicate that curcumin is quite safe and may exhibit therapeutic efficacy. This article reviews the main effects of curcumin on the different apoptotic signaling pathways involved in curcumin induced apoptosis in cancer cells via cellular transduction pathways and provides an in depth assessment of its pharmacological activity in the management of tumor progression.

Jak-Stat signaling pathway may play a role in the pathogenesis of cholesteatoma

PURPOSE

Jak-Stat signaling pathway is one of the major signal transduction cascades which regulates most of the cellular events such as cell proliferation, differentiation, cell migration and apoptosis. This study aims to determine the activity of Jak-Stat signaling pathway in the pathogenesis of cholesteatoma.

MATERIALS AND METHODS

Cholesteatoma and skin samples were obtained from 10 patients who underwent tympanomastoidectomy for chronic otitis media with cholesteatoma. Immunohistochemical analysis of cholesteatoma and skin was performed using anti-Jak1, anti-Jak2, anti-Jak3, anti-Stat1, anti-Stat2, anti-Stat3, anti-Stat4 and anti-Stat5 antibodies. The immunoreactivities in cholesteatoma and skin were quantified using H-score measurement and statistical comparison was performed.

RESULTS

Jak1, Jak2, Jak3, Stat1 and Stat3 immunoreactivities were not detected in cholesteatoma; in contrast to the skin (129.8; 226.7; 33.0; 66.4;115.9). In addition, when H-score measurements of Stat2, Stat4 and Stat5 immunoreactivities were compared between cholesteatoma (172.8; 166.7; 120.0) and skin (400.0; 284.9; 292.0), statistically significant differences were found (p<0.0001, p<0.0001, p<0.0001).

CONCLUSIONS

A remarkable deficiency in the family members of Jak-Stat signaling pathway was demonstrated in cholesteatoma. Therefore, perturbations in Jak-Stat signaling pathway may play a role in the pathogenesis of cholesteatoma.

Role of different regions of the hepatitis C virus genome in the therapeutic response to interferon-based treatment

Hepatitis C virus (HCV) is considered a significant risk factor in HCV-induced liver diseases and development of hepatocellular carcinoma (HCC). Nucleotide substitutions in the viral genome result in its diversification into quasispecies, subtypes and distinct genotypes. Different genotypes vary in their infectivity and immune response due to these nucleotide/amino acid variations. The current combination treatment for HCV infection is pegylated interferon α (PEG-IFN-α) with ribavirin, with a highly variable response rate mainly depending upon the HCV genotype. Genotypes 2 and 3 are found to respond better than genotypes 1 and 4, which are more resistant to IFN-based therapies. Different studies have been conducted worldwide to explore the basis of this difference in therapy response, which identified some putative regions in the HCV genome, especially in Core and NS5a, and to some extent in the E2 region, containing specific sequences in different genotypes that act differently with respect to the IFN response. In the review, we try to summarize the role of HCV proteins and their nucleotide sequences in association with treatment outcome in IFN-based therapy.

Loss of Jak2 impairs endothelial function by attenuating Raf-1/MEK1/Sp-1 signaling along with altered eNOS activities

A number of inhibitors have been used to dissect the functional relevance of Jak2 in endothelial homeostasis, with disparate results. Given that Jak2 deficiency leads to embryonic lethality, the exact role of Jak2 in the regulation of postnatal endothelial function is yet to be fully elucidated. We generated a model in which Jak2 deficiency can be induced by tamoxifen in adult mice. Loss of Jak2 significantly impaired endothelium-dependent response capacity for vasodilators. Matrigel plug assays indicated a notable decrease in endothelial angiogenic function in Jak2-deficient mice. Studies in a hindlimb ischemic model indicated that Jak2 activity is likely to be a prerequisite for prompt perfusion recovery, based on the concordance of temporal changes in Jak2 expression during the course of ischemic injury and perfusion recovery. A remarkable delay in perfusion recovery, along with reduced capillary and arteriole formation, was observed in Jak2-deficient mice. Antibody array studies indicated that loss of Jak2 led to repressed eNOS expression. In mechanistic studies, Jak2 deficiency attenuated Raf-1/MEK1 signaling, which then reduced activity of Sp-1, an essential transcription factor responsible for eNOS expression. These data are important not only for understanding the exact role that Jak2 plays in endothelial homeostasis, but also for assessing Jak2-based therapeutic strategies in a variety of clinical settings.

Lead identification of novel and selective TYK2 inhibitors

A therapeutic rationale is proposed for the treatment of inflammatory diseases, such as psoriasis and inflammatory bowel diseases (IBD), by selective targeting of TYK2. Hit triage, following a high-throughput screen for TYK2 inhibitors, revealed pyridine 1 as a promising starting point for lead identification. Initial expansion of 3 separate regions of the molecule led to eventual identification of cyclopropyl amide 46, a potent lead analog with good kinase selectivity, physicochemical properties, and pharmacokinetic profile. Analysis of the binding modes of the series in TYK2 and JAK2 crystal structures revealed key interactions leading to good TYK2 potency and design options for future optimization of selectivity.

Construction of network for protein kinases that play a role in acute pancreatitis

OBJECTIVES

This study aimed to search for protein kinases that play a role in acute pancreatitis and analyze their potential connection with each other.

METHODS

Information of human protein kinases were collected in protein kinase database, and then a systematic search was performed using PubMed for studies addressing the association between these kinases and acute pancreatitis. Gene Ontology Annotations were used to build interactions network for acute pancreatitis-associated protein kinases.

RESULTS

A total of 570 human protein kinases were found, in which 28 kinases play a role in acute pancreatitis. Among the 28 kinases, RIPK1, JAK2, SRC, EGFR, FYN, MET, JAK1, TYK2, and MTOR were annotated in Gene Ontology database. A gene ontology interactions network was built to visualize the common biological process these kinases participated in.

CONCLUSIONS

This study provides observations that protein kinases participate in all the sequential events in the exocrine pancreas in acute pancreatitis and that protein kinases are potential therapeutical target for acute pancreatitis.

MEK Is a Key Regulator of Gliogenesis in the Developing Brain

We have defined functions of MEK in regulating gliogenesis in developing cerebral cortex using loss- and gain-of-function mouse genetics. Radial progenitors deficient in both Mek1 and Mek2 fail to transition to the gliogenic mode in late embryogenesis, and astrocyte and oligodendroglial precursors fail to appear. In exploring mechanisms, we found that the key cytokine-regulated gliogenic pathway is attenuated. Further, the Ets transcription family member Etv5/Erm is strongly regulated by MEK and Erm overexpression can rescue the gliogenic potential of Mek-deleted progenitors. Remarkably, Mek1/2-deleted mice surviving postnatally exhibit cortices almost devoid of astrocytes and oligodendroglia and exhibit neurodegeneration. Conversely, expression of constitutively active MEK1 leads to a major increase in numbers of astrocytes in the adult brain. We conclude that MEK is essential for acquisition of gliogenic competence by radial progenitors and that levels of MEK activity regulate gliogenesis in the developing cortex.

SOCS proteins in infectious diseases of mammals

As for most biological processes, the immune response to microbial infections has to be tightly controlled to remain beneficial for the host. Inflammation is one of the major consequences of the host's immune response. For its orchestration, this process requires a fine-tuned interplay between interleukins, endothelial cells and various types of recruited immune cells. Suppressors of cytokine signalling (SOCS) proteins are crucially involved in the complex control of the inflammatory response through their actions on various signalling pathways including the JAK/STAT and NF-κB pathways. Due to their cytokine regulatory functions, they are frequent targets for exploitation by infectious agents trying to escape the host's immune response. This review article aims to summarize our current knowledge regarding SOCS family members in the different mammalian species studied so far, and to display their complex molecular interactions with microbial pathogens.

Astrocytes, but not microglia, rapidly sense H₂O₂via STAT6 phosphorylation, resulting in cyclooxygenase-2 expression and prostaglandin release

Emerging evidence has established that astrocytes, once considered passive supporting cells that maintained extracellular ion levels and served as a component of the blood-brain barrier, play active regulatory roles during neurogenesis and in brain pathology. In the current study, we demonstrated that astrocytes sense H(2)O(2) by rapidly phosphorylating the transcription factor STAT6, a response not observed in microglia. STAT6 phosphorylation was induced by generators of other reactive oxygen species (ROS) and reactive nitrogen species, as well as in the reoxygenation phase of hypoxia/reoxygenation, during which ROS are generated. Src-JAK pathways mediated STAT6 phosphorylation upstream. Experiments using lipid raft disruptors and analyses of detergent-fractionated cells demonstrated that H(2)O(2)-induced STAT6 phosphorylation occurred in lipid rafts. Under experimental conditions in which H(2)O(2) did not affect astrocyte viability, H(2)O(2)-induced STAT6 phosphorylation resulted in STAT6-dependent cyclooxygenase-2 expression and subsequent release of PGE(2) and prostacyclin, an effect also observed in hypoxia/reoxygenation. Finally, PGs released from H(2)O(2)-stimulated astrocytes inhibited microglial TNF-α expression. Accordingly, our results indicate that ROS-induced STAT6 phosphorylation in astrocytes can modulate the functions of neighboring cells, including microglia, through cyclooxygenase-2 induction and subsequent release of PGs. Differences in the sensitivity of STAT6 in astrocytes (highly sensitive) and microglia (insensitive) to phosphorylation following brief exposure to H(2)O(2) suggest that astrocytes can act as sentinels for certain stimuli, including H(2)O(2) and ROS, refining the canonical notion that microglia are the first line of defense against external stimuli.

Analysis of genomic aberrations and gene expression profiling identifies novel lesions and pathways in myeloproliferative neoplasms

Polycythemia vera (PV), essential thrombocythemia and primary myelofibrosis, are myeloproliferative neoplasms (MPNs) with distinct clinical features and are associated with the JAK2V617F mutation. To identify genomic anomalies involved in the pathogenesis of these disorders, we profiled 87 MPN patients using Affymetrix 250K single-nucleotide polymorphism (SNP) arrays. Aberrations affecting chr9 were the most frequently observed and included 9pLOH (n=16), trisomy 9 (n=6) and amplifications of 9p13.3–23.3 (n=1), 9q33.1–34.13 (n=1) and 9q34.13 (n=6). Patients with trisomy 9 were associated with elevated JAK2V617F mutant allele burden, suggesting that gain of chr9 represents an alternative mechanism for increasing JAK2V617F dosage. Gene expression profiling of patients with and without chr9 abnormalities (+9, 9pLOH), identified genes potentially involved in disease pathogenesis including JAK2, STAT5B and MAPK14. We also observed recurrent gains of 1p36.31–36.33 (n=6), 17q21.2–q21.31 (n=5) and 17q25.1–25.3 (n=5) and deletions affecting 18p11.31–11.32 (n=8). Combined SNP and gene expression analysis identified aberrations affecting components of a non-canonical PRC2 complex (EZH1, SUZ12 and JARID2) and genes comprising a ‘HSC signature' (MLLT3, SMARCA2 and PBX1). We show that NFIB, which is amplified in 7/87 MPN patients and upregulated in PV CD34+ cells, protects cells from apoptosis induced by cytokine withdrawal.

Transcriptional regulation of the intestinal luminal Na⁺ and Cl⁻ transporters

The epithelial apical membrane Na+/H+ exchangers [NHE (sodium hydrogen exchanger)2 and NHE3] and Cl-/HCO3- exchangers [DRA (down-regulated in adenoma) and PAT-1 (putative anion transporter 1)] are key luminal membrane transporters involved in electroneutral NaCl absorption in the mammalian intestine. During the last decade, there has been a surge of studies focusing on the short-term regulation of these electrolyte transporters, particularly for NHE3 regulation. However, the long-term regulation of the electrolyte transporters, involving transcriptional mechanisms and transcription factors that govern their basal regulation or dysregulation in diseased states, has only now started to unfold with the cloning and characterization of their gene promoters. The present review provides a detailed analysis of the core promoters of NHE2, NHE3, DRA and PAT-1 and outlines the transcription factors involved in their basal regulation as well as in response to both physiological (butyrate, protein kinases and probiotics) and pathophysiological (cytokines and high levels of serotonin) stimuli. The information available on the transcriptional regulation of the recently identified NHE8 isoform is also highlighted. Therefore the present review bridges a gap in our knowledge of the transcriptional mechanisms underlying the alterations in the gene expression of intestinal epithelial luminal membrane Na+ and Cl- transporters involved in electroneutral NaCl absorption. An understanding of the mechanisms of the modulation of gene expression of these transporters is important for a better assessment of the pathophysiology of diarrhoea associated with inflammatory and infectious diseases and may aid in designing better management protocols.

The antagonistic effect between STAT1 and Survivin and its clinical significance in gastric cancer

In previous studies, we observed that STAT1 and Survivin correlated negatively with gastric cancer tissues, and that the functions of the IFN-γ-STAT1 pathway and Survivin in gastric cancer are the same as those reported for other types of cancer. In this study, the SGC7901 gastric cancer cell line and 83 gastric cancer specimens were used to confirm the relationship between STAT1 and Survivin, as well as the clinical significance of this relationship in gastric cancer. IFN-γ and STAT1 and Survivin antisense oligonucleotides (ASONs) were used to knock down the expression in SGC7901 cells. The protein expression of STAT1 and Survivin was tested by immunocytochemical and image analysis methods. A gastric cancer tissue microarray was prepared and tested by immunohistochemical methods. Data were analyzed by the Spearman's rank correlation analysis, the χ(2) test and Cox's multivariate regression analysis. Upon knockdown of IFN-γ, STAT1 and Survivin expression by ASON in the SGC7901 cell line, an antagonistic effect was observed between STAT1 and Survivin. In gastric cancer tissues, STAT1 showed a negative correlation with depth of invasion (p<0.05) in gastric cancer tissues exhibiting a negative Survivin protein expression. Furthermore, in tissues exhibiting a negative STAT1 protein expression, Survivin correlated negatively with N stage (p<0.05). Pathological and molecular markers were used to conduct Cox's multivariate regression analysis, and depth of invasion and N stage were found to be prognostic factors (p<0.05). On the other hand, in tissues exhibiting a negative Survivin protein expression, Cox's multivariate regression analysis revealed that the differentiation type and STAT1 protein expression were prognostic factors (p<0.05). There is an antagonistic effect between STAT1 and Survivin in gastric cancer, and this antagonistic effect is of clinical significance in gastric cancer.

STAT6 expression in glioblastoma promotes invasive growth

BACKGROUND

Glioblastoma (GBM) is a highly aggressive malignant primary brain tumor, characterized by rapid growth, diffuse infiltration of cells into both adjacent and remote brain regions, and a generalized resistance to currently available treatment modalities. Recent reports in the literature suggest that Signal Transducers and Activators of Transcription (STATs) play important roles in the regulation of GBM pathophysiology.

METHODS

STAT6 protein expression was analyzed by Western blotting in GBM cell lines and by immunohistochemistry in a tissue microarray (TMA) of glioma patient tissues. We utilized shRNA against STAT6 to investigate the effects of prolonged STAT6 depletion on the growth and invasion of two STAT6-positive GBM cell lines. Cell proliferation was assessed by measuring (3)H-Thymidine uptake over time. Invasion was measured using an in vitro transwell assay in which cells invade through a type IV collagen matrix toward a chemoattractant (Fetal Bovine Serum). Cells were then stained and counted. Kaplan-Meyer survival curves were generated to show the correlation between STAT6 gene expression and patient survival in 343 glioma patients and in a subset of patients with only GBM. Gene expression microarray and clinical data were acquired from the Rembrandt 1 public data depository (https://caintegrator.nci.nih.gov/rembrandt/). Lastly, a genome-wide expression microarray analysis was performed to compare gene expression in wild-type GBM cells to expression in stable STAT6 knockdown clones.

RESULTS

STAT6 was expressed in 2 GBM cell lines, U-1242MG and U-87MG, and in normal astrocytes (NHA) but not in the U-251MG GBM cell line. In our TMA study, STAT6 immunostaining was visible in the majority of astrocytomas of all grades (I-IV) but not in normal brain tissue. In positive cells, STAT6 was localized exclusively in the nuclei over 95% of the time. STAT6-deficient GBM cells showed a reduction in (3)H-Thymidine uptake compared to the wild-type. There was some variation among the different shRNA- silenced clones, but all had a reduction in (3)H-Thymidine uptake ranging from 35%- 70% in U-1242MG and 40- 50% in U-87MG cells. Additionally, STAT6- depleted cells were less invasive than controls in our in vitro transmembrane invasion assay. Invasiveness was decreased by 25-40% and 30-75% in U-1242MG and U-87MG cells, respectively. The microarray analysis identified matrix metalloproteinase 1 (MMP-1) and urokinase Plasminogen activator (uPA) as potential STA6 target genes involved in the promotion of GBM cell invasion. In a Kaplan-Meier survival curve based on Rembrandt 1 gene expression microarray and clinical data, there was a significant difference in survival (P < 0.05) between glioma patients with up- and down-regulated STAT6. Decreased STAT6 expression correlated with longer survival times. In two subsets of patients with either grade IV tumors (GBM) or Grade II/III astrocytomas, there was a similar trend that however did not reach statistical significance.

CONCLUSIONS

Taken together, these findings suggest a role for STAT6 in enhancing cell proliferation and invasion in GBM, which may explain why up-regulation of STAT6 correlates with shorter survival times in glioma patients. This report thus identifies STAT6 as a new and potentially promising therapeutic target.

Potential role of NADPH oxidase-mediated activation of Jak2/Stat3 and mitogen-activated protein kinases and expression of TGF-β1 in the pathophysiology of acute pancreatitis

OBJECTIVE

NADPH oxidase is potentially associated with acute pancreatitis by producing reactive oxygen species (ROS). We investigated whether NADPH oxidase mediates the activation of Janus kinase (Jak)2/signal transducers and activators of transcription (Stat)3 and mitogen-activated protein kinases (MAPKs) to induce the expression of transforming growth factor-β1 (TGF-β1) in cerulein-stimulated pancreatic acinar cells.

TREATMENT

AR42J cells were treated with an NADPH oxidase inhibitor diphenyleneiodonium (DPI) or a Jak2 inhibitor AG490. Other cells were transfected with antisense or sense oligonucleotides (AS or S ODNs) for NADPH oxidase subunit p22(phox) or p47(phox).

METHODS

TGF-β1 was determined by enzyme-linked immonosorbent assay. STAT3-DNA binding activity was measured by electrophoretic mobility shift assay. Levels of MAPKs as well as total and phospho-specific forms of Jak1/Stat3 were assessed by Western blot analysis.

RESULTS

Cerulein induced increases in TGF-β1, Stat3-DNA binding activity and the activation of MAPKs in AR42J cells. AG490 suppressed these cerulein-induced changes, similar to inhibition by DPI. Cerulein-induced activation of Jak2/Stat3 and increases in MAPKs and TGF-β1 levels were inhibited in the cells transfected with AS ODN for p22(phox) and p47(phox) compared to S ODN controls.

CONCLUSION

Inhibition of NADPH oxidase may be beneficial for prevention and treatment of pancreatitis by suppressing Jak2/Stat3 and MAPKs and expression of TGF-β1 in pancreatic acinar cells.

Impact of SOCS3 overexpression on human skeletal muscle development in vitro

The Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling cascade has been identified as a crucial factor for myogenesis. The STAT3 isoform is essential for satellite cell migration and myogenic differentiation as it mediates the expression of muscle specific myogenic factors. The SOCS (suppressors of cytokine signaling) family of proteins down-regulates STAT activation. Primary human skeletal muscle cells were isolated and cultured to investigate the effect of SOCS3 adenoviral overexpression on myotube maturation. It was demonstrated that STAT3 inhibition did not influence myotube development or survival. Moreover, SOCS3 overexpression enhances the mRNA expression of downstream targets of STAT3, c-FOS and VEGF. These increases were correlated with enhanced mRNA expression of genes associated with muscle maturation and hypertrophy. Thus SOCS3 influences myoblast differentiation and SOCS3 may be significant in regulating the activity of genes previously identified as transcriptionally regulated by STAT3.