Regulation Of STAT3 Research Articles

The leukemia inhibitory factor regulates fibroblast growth factor receptor 4 transcription in gastric cancer.

The gastric adenocarcinoma (GC) represents the third cause of cancer-related mortality worldwide, and available therapeutic options remain sub-optimal. The Fibroblast growth factor receptors (FGFRs) are oncogenic transmembrane tyrosine kinase receptors. FGFR inhibitors have been approved for the treatment of various cancers and a STAT3-dependent regulation of FGFR4 has been documented in the H.pylori infected intestinal GC. Therefore, the modulation of FGFR4 might be useful for the treatment of GC. To investigate wich factors could modulate FGFR4 signalling in GC, we employed RNA-seq analysis on GC patients biopsies, human patients derived organoids (PDOs) and cancer cell lines. We report that FGFR4 expression/function is regulated by the leukemia inhibitory factor (LIF) an IL-6 related oncogenic cytokine, in JAK1/STAT3 dependent manner. The transcriptomic analysis revealed a direct correlation between the expression of LIFR and FGFR4 in the tissue of an exploratory cohort of 31 GC and confirmed these findings by two external validation cohorts of GC. A LIFR inhibitor (LIR-201) abrogates STAT3 phosphorylation induced by LIF as well as recruitment of pSTAT3 to the promoter of FGFR4. Furthermore, inhibition of FGFR4 by roblitinib or siRNA abrogates STAT3 phosphorylation and oncogentic effects of LIF in GC cells, indicating that FGFR4 is a downstream target of LIF/LIFR complex. Treating cells with LIR-201 abrogates oncogenic potential of FGF19, the physiological ligand of FGFR4. Together these data unreveal a previously unregnized regulatory mechanism of FGFR4 by LIF/LIFR and demonstrate that LIF and FGF19 converge on the regulation of oncogenic STAT3 in GC cells.

LB06 - Mechanism of IL-6/STAT3 regulation of SRD5A1 in prostate cancer cells

LB06 - Mechanism of IL-6/STAT3 regulation of SRD5A1 in prostate cancer cells

A Combination of CPI-0610 and SAHA Induces Apoptosis through STAT3 and p38 Signalling Pathways in Diffuse Large B-cell Lymphoma Cells.

Although immunotherapies have greatly improved diffuse large B-cell lymphoma (DLBCL) prognosis, a proportion of patients remain to be relapsed or refractory. Therefore, the identification of novel therapeutic targets and drugs is urgently required. Inhibition of the bromodomain and extra-terminal (BET) proteins has been a promising therapeutic strategy for various haematologic cancers. CPI-0610 is a potent and selective BET inhibitor. The effects of CPI-0610 in DLBCL cells have not been reported yet. The aim of this study was to assess the effects of CPI-0610 in DLBCL and its underlying mechanisms. DLBCL cells were treated with CPI-0610, followed by measuring cell viability, cell cycle, apoptosis, autophagy, and specific cell signaling pathways. Moreover, immunodeficient mice were engrafted with SUDHL2 cells and then treated with CPI-0610 for analysis of tumor burden. We also analyzed the synergistic effect of CPI-0610 with histone deacetylase inhibitor suberoylanilide hydroxamic acid. The present study demonstrated that CPI-0610 displayed cell cytotoxicity by arresting the G1 cell cycle and inducing endogenous and exogenous apoptotic pathways. Additionally, CPI-0610 decreased BRD4 and c-Myc expressions and affected MAPK, JAK/STAT, and AKT signalling pathways in human DLBCL cells. An in vivo experiment exhibited that CPI-0610 decreased the primary tumour growth of the DLBCL xenograft model. Furthermore, the use of CPI-0610 in combination with suberoylanilide hydroxamic acid exhibited a specific synergistic effect in inducing apoptosis through the regulation of STAT3 and p38. Targeting BET may be an effective therapeutic strategy and potentiated by a combination with histone deacetylase inhibition in DLBCL.

The Cell-Autonomous Pro-Metastatic Activities of PD-L1 in Breast Cancer Are Regulated by N-Linked Glycosylation-Dependent Activation of STAT3 and STAT1.

PD-L1 has been characterized as an inhibitory immune checkpoint, leading to the suppression of potential anti-tumor immune activities in many cancer types. In view of the relatively limited efficacy of immune checkpoint blockades against PD-L1 in breast cancer, our recent study addressed the possibility that in addition to its immune-inhibitory functions, PD-L1 promotes the pro-metastatic potential of the cancer cells themselves. Indeed, our published findings demonstrated that PD-L1 promoted pro-metastatic functions of breast cancer cells in a cell-autonomous manner, both in vitro and in vivo. These functions fully depended on the integrity of the S283 intracellular residue of PD-L1. Here, using siRNAs and the S283A-PD-L1 variant, we demonstrate that the cell-autonomous pro-metastatic functions of PD-L1-tumor cell proliferation and invasion, and release of the pro-metastatic chemokine CXCL8-required the activation of STAT3 and STAT1 in luminal A and triple-negative breast cancer cells. The cell-autonomous pro-metastatic functions of PD-L1 were potently impaired upon inhibition of N-linked glycosylation (kifunensine). Site-specific mutants at each of the N-linked glycosylation sites of PD-L1 (N35, N192, N200, and N219) revealed that they were all required for PD-L1-induced pro-metastatic functions to occur; the N219 site was the main regulator of STAT3 and STAT1 activation, with accompanying roles for N192 and N200 (depending on the cell type). Using a T cell-independent mouse system, we found that cells expressing N35A-PD-L1 and N219A-PD-L1 had a significantly lower tumorigenic and metastatic potential than cells expressing WT-PD-L1. TCGA analyses revealed significant associations between reduced survival and high levels of α-mannosidase II (inferring on N-linked glycosylation) in breast cancer patients. These findings suggest that N-linked glycosylation of PD-L1 may be used to screen for patients who are at greater risk of disease progression, and that modalities targeting N-linked glycosylated PD-L1 may lead to the inhibition of its cell-autonomous pro-metastatic functions and to lower tumor progression in breast cancer.

Cancer associated fibroblast derived SLIT2 drives gastric cancer cell metastasis by activating NEK9

The secretory properties of cancer-associated fibroblasts (CAFs) play predominant roles in shaping a pro-metastatic tumor microenvironment. The present study demonstrated that SLIT2, an axon guidance protein, produced by CAFs and promoted gastric cancer (GC) metastasis in two gastric cancer cell lines (AGS and MKN45) by binding to roundabout guidance receptor 1 (ROBO1). Mass-spectrometry analysis revealed that ROBO1 could interact with NEK9, a serine/threonine kinase. And their mutual binding activities were further enhanced by SLIT2. Domain analysis revealed the kinase domain of NEK9 was critical in its interaction with the intracellular domain (ICD) of ROBO1, and it also directly phosphorylated tripartite motif containing 28 (TRIM28) and cortactin (CTTN) in AGS and MKN45 cells. TRIM28 function as a transcriptional elongation factor, which directly facilitate CTTN activation. In addition, Bioinformatics analysis and experimental validation identified transcriptional regulation of STAT3 and NF-κB p100 by TRIM28, and a synergetic transcription of CTTN by STAT3 and NF-κB p100 was also observed in AGS and MKN45. Therefore, CAF-derived SLIT2 increased the expression and phosphorylation levels of CTTN, which induced cytoskeletal reorganization and GC cells metastasis. A simultaneous increase in the expression levels of NEK9, TRIM28 and CTTN was found in metastatic GC lesions compared with paired non-cancerous tissues and primary cancer lesions via IHC and Multiplex IHC. The analysis of the data from a cohort of patients with GC revealed that increased levels of NEK9, TRIM28 and CTTN were associated with a decreased overall survival rate. On the whole, these findings revealed the connections of CAFs and cancer cells through SLIT2/ROBO1 and inflammatory signaling, and the key molecules involved in this process may serve as potential biomarkers and therapeutic targets for GC.

Dermokine mutations contribute to epithelial-mesenchymal transition and advanced melanoma through ERK/MAPK pathways.

To discover vulnerabilities associated with dermokine (DMKN) as a new trigger of the epithelial-mesenchymal transition (EMT) -driven melanoma, we undertook a genome-wide genetic screening using transgenic. Here, we showed that DMKN expression could be constitutively increased in human malignant melanoma (MM) and that this correlates with poor overall survival in melanoma patients, especially in BRAF-mutated MM samples. Furthermore, in vitro, knockdown of DMKN inhibited the cell proliferation, migration, invasion, and apoptosis of MM cancer cells by the activation of ERK/MAPK signaling pathways and regulator of STAT3 in downstream molecular. By interrogating the in vitro melanoma dataset and characterization of advanced melanoma samples, we found that DMKN downregulated the EMT-like transcriptional program by disrupting EMT cortical actin, increasing the expression of epithelial markers, and decreasing the expression of mesenchymal markers. In addition, whole exome sequencing was presented with p.E69D and p.V91A DMKN mutations as a novel somatic loss of function mutations in those patients. Moreover, our purposeful proof-of-principle modeled the interaction of ERK with p.E69D and p.V91A DMKN mutations in the ERK-MAPK kinas signaling that may be naturally associated with triggering the EMT during melanomagenesis. Altogether, these findings provide preclinical evidence for the role of DMKN in shaping the EMT-like melanoma phenotype and introduced DMKN as a new exceptional responder for personalized MM therapy.

P-345 GM-CSF drives endometrial repair via p-STAT3 mediating angiogenesis

Abstract Study question Does granulocyte macrophage colony-stimulating factor (GM-CSF) play a role in endometrial angiogenesis and can it be used as a new application for treating endometrial regeneration? Summary answer GM-CSF improves endometrial repair via promoting endometrial angiogenesis and may provide a novel insight and therapeutics for endometrial injury. What is known already GM-CSF is a cytokine normally expressed in the female reproductive tract and plays key roles in embryo implantation and subsequent development. Our previous study found that intraperitoneally （i.p.）injection of GM-CSF can significantly improve endometrial repair by promoting endometrial glandular cells proliferation and stromal cells migration, increasing the thickness of endometrium and embryo implantation in mice. However, whether GM-CSF is involved in endometrial angiogenesis is unknown. Study design, size, duration To observe whether angiogenesis is promoted by GM-CSF, the expression of angiogenic factor CD31 was evaluated after injection of GM-CSF into endometrial injured mice model. The effect of GM-CSF on vascular g regeneration was also explored by zebrafish embryo model of intersegmental vascular injury. Human umbilical vein vascular endothelial cells (HUVECs) were cultured in vitro, and the role of GM-CSF on HUVECs were examined through EdU, Tube formation, Scratch repair and Transwell assays. Participants/materials, setting, methods 20μl 90% ethanol was used to establish endometrial injured mice model. After modeling, compared with i.p. injection of GM-CSF and saline, observing whether GM-CSF had the effect of repairing angiogenesis of injured endometrium, by evaluating expression of CD31. Real-time PCR, Western Blot were used to verify differentially expressed levels of mRNA and protein. Western Blot was used to confirm protein location. ChIP was used to analyze stat3 regulation of GM-CSF. Main results and the role of chance GM-CSF promoted expression of angiogenic factor CD31 in the mice model of endometrial injury. GM-CSF can repair and regenerate the zebrafish embryo model of intersegmental vascular injury caused by Sorafenib. GM-CSF can promote angiogenesis by HUVECs proliferation and migration, and significantly increase the formation of vascular-like network structures In GM-CSF treatment group, the mRNA expression of VEGF, MMP2, Ang1, Ang2 and Tie2 mRNA in HUVECs cells increased significantly; GM-CSF can activate the phosphorylation expression levels of p-FAK, p-Src, p-ERK 1/2, p-STAT3, p-p38 MAPK, pc-Jun, p-CREB, p-Akt, and p-eNOS. And it can increase the expression of downstream VEGF and MMP2 proteins. GM-CSF treatment for 30 min can promote phosphorylation and translocation of STAT3 from cytoplasm to nucleus, thereby regulating the expression of VEGF and MMP2 downstream. While FAK inhibitors (PF573228) and STAT3 knockdown can abrogate GM-CSF effect on HUVECs. Limitations, reasons for caution The results at the cellular and animal level can’t be completely mimic human endometrial injury. In future, well-designed clinical trials are needed to investigate the efficacy and safety of GM-CSF for treatment of human endometrial vascular injury. Wider implications of the findings GM-CSF can promote the vascular regeneration in mice model of endometrial injury through p-STAT3. Our findings provide new ideas for clinical treatment of endometrial injury. Trial registration number Not applicable

Capsaicin functions as a selective degrader of STAT3 to enhance host resistance to viral infection.

Although STAT3 has been reported as a negative regulator of type I interferon (IFN) signaling, the effects of pharmacologically inhibiting STAT3 on innate antiviral immunity are not well known. Capsaicin, approved for the treatment of postherpetic neuralgia and diabetic peripheral nerve pain, is an agonist of transient receptor potential vanilloid subtype 1 (TRPV1), with additional recognized potencies in anticancer, anti-inflammatory, and metabolic diseases. We investigated the effects of capsaicin on viral replication and innate antiviral immune response and discovered that capsaicin dose-dependently inhibited the replication of VSV, EMCV, and H1N1. In VSV-infected mice, pretreatment with capsaicin improved the survival rate and suppressed inflammatory responses accompanied by attenuated VSV replication in the liver, lung, and spleen. The inhibition of viral replication by capsaicin was independent of TRPV1 and occurred mainly at postviral entry steps. We further revealed that capsaicin directly bound to STAT3 protein and selectively promoted its lysosomal degradation. As a result, the negative regulation of STAT3 on the type I IFN response was attenuated, and host resistance to viral infection was enhanced. Our results suggest that capsaicin is a promising small-molecule drug candidate, and offer a feasible pharmacological strategy for strengthening host resistance to viral infection.

MSL1 Promotes Liver Regeneration by Driving Phase Separation of STAT3 and Histone H4 and Enhancing Their Acetylation.

Male-specific lethal 1 (MSL1) is critical for the formation of MSL histone acetyltransferase complex which acetylates histone H4 Lys16 (H4K16ac) to activate gene expression. However, the role of MSL1 in liver regeneration is poorly understood. Here, this work identifies MSL1 as a key regulator of STAT3 and histone H4 (H4) in hepatocytes. MSL1 forms condensates with STAT3 or H4 through liquid-liquid phase separation to enrich acetyl-coenzyme A (Ac-CoA), and Ac-CoA in turn enhances MSL1 condensate formation, synergetically promoting the acetylation of STAT3 K685 and H4K16, thus stimulating liver regeneration after partial hepatectomy (PH). Additionally, increasing Ac-CoA level can enhance STAT3 and H4 acetylation, thus promoting liver regeneration in aged mice. The results demonstrate that MSL1 condensate-mediated STAT3 and H4 acetylation play an important role in liver regeneration. Thus, promoting the phase separation of MSL1 and increasing Ac-CoA level may be a novel therapeutic strategy for acute liver diseases and transplantation.

Protein Kinase CK2 Promotes Proliferation, Abnormal Differentiation, and Proinflammatory Cytokine Production of Keratinocytes via Regulation of STAT3 and Akt Pathways in Psoriasis

Protein kinase CK2 is a constitutively active and ubiquitously expressed serine/threonine kinase that is closely associated with various types of cancers, autoimmune disorders, and inflammation. However, the role of CK2 in psoriasis remains unknown. Herein, the study indicated elevated expression of CK2 in skin lesions from patients with psoriasis and from psoriasis-like mice. In the psoriasis-like mouse model, the CK2-specific inhibitor CX-4945 ameliorated imiquimod-induced psoriasis symptoms with reduced proliferation, abnormal differentiation, inflammatory cytokine production (especially IL-17A) of keratinocytes, and infiltration of γδ T cells. In invitro studies, exogenous CK2 promoted hyperproliferation and abnormal differentiation of human keratinocytes, which were reversed by the suppression of CK2 with CX-4945 or siRNA. Furthermore, knockdown of CK2 reduced IL-17A expression and abolished IL-17A-induced proliferation and inflammatory cytokine expression in keratinocytes. Interestingly, IL-17A increased the expression of CK2 in keratinocytes, thereby establishing a positive feedback loop. In addition, suppression of CK2 inhibited the activation of STAT3 and Akt signaling pathways in human keratinocytes and imiquimod-induced psoriatic lesions of mice. These findings indicate that a highly expressed CK2 level in the skin lesions is required in the development of psoriasis by promoting epidermal hyperplasia, abnormal differentiation, and inflammatory response via regulation of the STAT3 and Akt signaling pathways. CK2 may be a target for the treatment of psoriasis.

Retraction: Profibrogenic phenotype in caveolin-1 deficiency via differential regulation of STAT-1/3 proteins.

Retraction: Profibrogenic phenotype in caveolin-1 deficiency via differential regulation of STAT-1/3 proteins.

Effective oxygen metabolism-based prognostic signature for colorectal cancer.

Oxygen metabolism is an important factor affecting the development of tumors, but its roles and clinical value in Colorectal cancer are not clear. We developed an oxygen metabolism (OM) based prognostic risk model for colorectal cancer and explored the role of OM genes in cancer. Gene expression and clinical data obtained from The Cancer Genome Atlas, Clinical Proteomic Tumor Analysis Consortium databases were consider as discovery and validation cohort, respectively. The prognostic model based on differently expressed OM genes between tumor and GTEx normal colorectal tissues were constructed in discovery cohort and validated in validation cohort. The Cox proportional hazards analysis was used to test clinical independent. Upstream and downstream regulatory relationships and interaction molecules are used to clarify the roles of prognostic OM genes in colorectal cancer. A total of 72 common differently expressed OM genes were detected in the discovery and validation set. A five-OM gene prognostic model including LRT2, ATP6V0E2, ODC1, SEL1L3 and VDR was established and validated. Risk score determined by the model was an independent prognostic according to routine clinical factors. Besides, the role of prognostic OM genes involves transcriptional regulation of MYC and STAT3, and downstream cell stress and inflammatory response pathways. We developed a five-OM gene prognostic model and study the unique roles of oxygen metabolism in of colorectal cancer.

STAT3 regulation of Mtb-specific T cell function in active pulmonary tuberculosis patients

BackgroundTuberculosis (TB) remains one of the most serious infectious diseases in the world. Our aim was to investigate the regulatory role of STAT3 and pSTAT3 in the regulation of T cell immunophenotype and cell function. MethodsTwenty-five active pulmonary tuberculosis (APTB) patients, 18 latent tuberculosis infection (LTBI) patients, and 20 healthy controls (HCs) enrolled in this study. T cell phenotype and expression of STAT3 and pSTAT3 were detected by flow cytometry. ResultsCompared with HCs, the expression of pSTAT3 in CD4+ T and CD8+ T cells in peripheral blood of APTB patients was increased, and the expression was higher in pleural effusion. Multifunctional T cells that simultaneously secrete IFN-γ, TNF-α and IL-17A have higher pSTAT3 expression levels. Mtb-specific T cells from APTB patients had a higher cell frequency of the STAT3+ pSTAT3+ phenotype and a reduced cell frequency of the STAT3+ pSTAT3- phenotype compared with LTBI patients. Mtb-specific T cells with STAT3+ pSTAT3+ phenotype had higher expression of PD-1 and PD-L1, while cells with STAT3+ pSTAT3- phenotype had higher expression of Bcl-2. ConclusionsSTAT3 and pSTAT3 in T cells of APTB patients feature in the process of anti-apoptosis and cytokine secretion. At the same time, the higher pSTAT3 may be related to the degree of cell functional exhaustion. The pSTAT3 level of T cells is related to the infection status and may indicate the clinical activity of the disease, which provides a new idea for the clinical identification and treatment of active pulmonary tuberculosis.

STAT3 Protects Hematopoietic Stem and Progenitor Cell Function in Non-Inflamed Conditions

The transcriptional regulator STAT3 has well established anti-inflammatory functions in mature myeloid cells by preventing excessive pro-inflammatory factor production in response to Toll-like receptor agonists or the gut microbiota. However, this role has precluded understanding of STAT3 function in maintaining hematopoietic stem and progenitor cell (HSPC) homeostasis, as Stat3 deletion in the hematopoietic system leads to systemic inflammation and ineffective hematopoiesis. Therefore, novel experimental approaches are needed to uncouple STAT3 function in HSPCs from the effects of systemic inflammation. To understand how STAT3 regulates hematopoietic homeostasis in a non-inflamed environment, we developed competitive mixed bone marrow (BM) chimeric mice with conditional Stat3 deletion in approximately 20% of hematopoietic cells (Figure 1a). We demonstrated successful engraftment of test (CD45.2+ CreER or CD45.2+ CreER Stat3f/f) and competitor (CD45.1+CD45.2+) BM cells at a 1:4 ratio, respectively, in lethally-irradiated CD45.1+ recipient mice. Then, we induced Stat3 deletion by tamoxifen treatment (Figure 1a). We found a significant impairment in the hematopoietic activity of Stat3-deficient HSPCs, as shown by ~50% reduction of peripheral blood CD45.2+ cells after Stat3 deletion, which suggests a crucial role of STAT3 in sustaining hematopoiesis (Figure 1b). Serum cytokine levels and colon pathology scores were similar between mice with Stat3-deficient cells and corresponding CreER controls, which confirms a non-inflammatory environment. We also observed loss of a majority of CD45.2+ immune lineages in spleen, colon, and BM upon Stat3 deletion. To evaluate the self-renewal capability of Stat3-deficient hematopoietic stem cells (HSCs), we performed secondary BM transplantation experiments. These experiments showed that CD45.2+Stat3-deficient HSCs could not reconstitute peripheral blood populations. Moreover, we found a striking decline in Stat3-deficient lin-Sca-1+ckit+ (LSK) cells and HSCs (LSK CD48-CD150+) in secondary BM transplants (Figure 1c). These results suggests that STAT3 is required to sustain a functional HSC compartment in non-inflamed conditions. To investigate how loss of STAT3 affects the transcriptional landscape of HSPCs, we performed scRNA-sequencing (scRNA-seq) in phenotypically defined LSKs isolated from primary BM transplant recipients. This analysis identified 12 distinct transcriptional states in the LSK compartment (Figure 1d). Compared with CreER control cells, Stat3-deficient LSKs were enriched in myeloid-related clusters at the expense of lymphoid clusters. Differential expression analysis among the clusters revealed that Stat3-deficient HSCs (Cluster 3) and multipotent progenitors (Cluster 2) upregulated Myc and Interferon (IFN) Alpha Response pathways, including genes involved in cell cycle activation, IFN-stimulated genes (Ifi203, Mndal), and IFN transcriptional regulators (Irf1, Irf2, Irf2bp2) (Figure 1e). In addition, Stat3-deficient LSKs acquired γH2AX modifications over time. Collectively, these data suggest that Stat3 deletion induces excessive DNA damage and intrinsic activation of an IFN transcriptional signature in HSPCs, which leads to impairment of HSC function. In conclusion, our results reveal a cell-autonomous role for STAT3 in preserving hematopoietic stem and progenitor cell homeostasis, sustaining long-term HSC function, and preventing induction of an intrinsic IFN response and DNA damage (Figure 1f). Our study highlights STAT3-driven protective mechanisms in HSPCs under non-inflammatory conditions. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

ODP201 Fyn regulates sarcopenia via autophagy

Abstract Sarcopenia is an important element that impairs daily activity. Sarcopenia is also linked to insulin resistance, and the number of diabetic patients also presenting sarcopenia is increasing. In recent years, autophagy has been identified as one of the novel mechanisms associated with sarcopenia. We previously reported that Fyn not only participates in the metabolic syndrome but also that autophagy-regulating sarcopenia was decreased in muscle specific Fyn transgenic mice through STAT3 regulation (Cell metabolism 2010, Cell Rep. 2012). More recently, we revealed Fyn-dependent STAT3 phosphorylation by IL6, which is involved in chronic inflammation and metabolic syndrome, using mouse C2C12 myotube cells expressing shRNA for Fyn. Furthermore, using WT mice with both the denervated and the hind limb suspension (HS) that promotes disuse atrophy by suspending the hind limb, not only both Fyn and IL6 gene expressions were increased but the expression and phosphorylation levels of STAT3 were also augmented, while the autophagic activity was decreased. To confirm those regulations are Fyn dependent, we took advantage of Fyn null mice (FynKO) with HS. Compare to WT mice with HS, all the muscles of FynKO were resistant for the loss of muscle mass induced by HS. The expressions of bothatrogin-1 and muRF-1,the key muscle specific E3 ubiquitin ligases as well as the markers for sarcopenia, were not changed in the muscles of FynKO with HS. Moreover, the STAT3 phosphorylation on tyrosine 705 was decreased in the muscle of FynKO compared to WT mice after hind limb suspension, while expression levels of STAT3 were not changed. IL-6mRNA expression levels were increased in the HS muscle of control mice, but were not changed in FynKO HS muscle. Finally, the autophagic activity, examined by both LC3-2 protein levels after intraperitoneal administration of colchicine andSQSTM1/p62 immunofluorescence in muscles, was retained in FynKO after HS. These results strongly suggest that Fyn is involved not only in the metabolic syndrome but also in the pathogenesis of sarcopenia, and may lead to a better understanding of the pathology of sarcopenia-associated obesity and the development of therapeutic methods. Presentation: No date and time listed

Dietary phytate primes epithelial antibacterial immunity in the intestine.

Although diet has long been associated with susceptibility to infection, the dietary components that regulate host defense remain poorly understood. Here, we demonstrate that consuming rice bran decreases susceptibility to intestinal infection with Citrobacter rodentium, a murine pathogen that is similar to enteropathogenic E. coli infection in humans. Rice bran naturally contains high levels of the substance phytate. Interestingly, phytate supplementation also protected against intestinal infection, and enzymatic metabolism of phytate by commensal bacteria was necessary for phytate-induced host defense. Mechanistically, phytate consumption induced mammalian intestinal epithelial expression of STAT3-regulated antimicrobial pathways and increased phosphorylated STAT3, suggesting that dietary phytate promotes innate defense through epithelial STAT3 activation. Further, phytate regulation of epithelial STAT3 was mediated by the microbiota-sensitive enzyme histone deacetylase 3 (HDAC3). Collectively, these data demonstrate that metabolism of dietary phytate by microbiota decreases intestinal infection and suggests that consuming bran and other phytate-enriched foods may represent an effective dietary strategy for priming host immunity.

STAT3 Inhibits Autocrine IFN Signaling in Type I Conventional Dendritic Cells.

Type I conventional dendritic cells (cDC1s) are an essential Ag-presenting population required for generating adaptive immunity against intracellular pathogens and tumors. While the transcriptional control of cDC1 development is well understood, the mechanisms by which extracellular stimuli regulate cDC1 function remain unclear. We previously demonstrated that the cytokine-responsive transcriptional regulator STAT3 inhibits polyinosinic:polycytidylic acid [poly(I:C)]-induced cDC1 maturation and cDC1-mediated antitumor immunity in murine breast cancer, indicating an intrinsic, suppressive role for STAT3 in cDC1s. To probe transcriptional mechanisms regulating cDC1 function, we generated novel RNA sequencing datasets representing poly(I:C)-, IL-10-, and STAT3-mediated gene expression responses in murine cDC1s. Bioinformatics analyses indicated that poly(I:C) stimulates multiple inflammatory pathways independent of STAT3, while IL-10-activated STAT3 uniquely inhibits the poly(I:C)-induced type I IFN (IFN-I) transcriptional response. We validated this mechanism using purified cDC1s deficient for STAT3 or IFN signaling. Our data reveal IL-10-activated STAT3 suppresses production of IFN-β and IFN-γ, accrual of tyrosine phosphorylated STAT1, and IFN-stimulated gene expression in cDC1s after poly(I:C) exposure. Moreover, we found that maturation of cDC1s in response to poly(I:C) is dependent on the IFN-I receptor, but not the type II IFN receptor, or IFN-λ. Taken together, we elucidate an essential role for STAT3 in restraining autocrine IFN-I signaling in cDC1s elicited by poly(I:C) stimulation, and we provide novel RNA sequencing datasets that will aid in further delineating inflammatory and anti-inflammatory mechanisms in cDC1s.

Interferon-gamma modulates articular chondrocyte and osteoblast metabolism through protein kinase R-independent and dependent mechanisms

Osteoarthritis (OA) affects multiple tissues of the synovial joint and is characterised by articular cartilage degeneration and bone remodelling. Interferon-γ (IFN-γ) is implicated in osteoarthritis pathology exerting its biological effects via various mechanisms including activation of protein kinase R (PKR), which has been implicated in inflammation and arthritis. This study investigated whether treatment of articular cartilage chondrocytes and osteoblasts with IFN-γ could induce a degradative phenotype that was mediated through the PKR signalling pathway. IFN-γ treatment of chondrocytes increased transcription of key inflammatory mediators (TNF-α, IL-6), matrix degrading enzymes (MMP-13), the transcription factor STAT1, and PKR. Activation of PKR was involved in the regulation of TNF-α, IL-6, and STAT1. In osteoblasts, IFN-γ increased human and mouse STAT1, and human IL-6 through a mechanism involving PKR. ALP, COL1A1 (human and mouse), RUNX2 (mouse), and PHOSPHO1 (mouse) were decreased by IFN-γ. The number of PKR positive cells were increased in post-traumatic OA (PTOA). This study has revealed that IFN-γ propagates inflammatory and degenerative events in articular chondrocytes and osteoblasts via PKR activation. Since IFN-γ and PKR signalling are both activated in early PTOA, these mechanisms are likely to contribute to joint degeneration after injury and might offer attractive targets for therapeutic intervention.

Overexpression of miR-125a-5p Inhibits Hepatocyte Proliferation through the STAT3 Regulation In Vivo and In Vitro.

microRNAs (miRNAs) are critically involved in liver regeneration (LR). miR-125a-5p (miR-125a) is a tumor-suppressing miRNA, but its role in LR has not been studied. Our previous studies have proved that miR-125a was related to LR at the initiation phase, while the mechanism hepatocyte proliferation triggered by miR-125a in LR has been rarely evaluated. Herein, we mainly studied the molecular mechanism of miR-125a in triggering hepatocyte proliferation and the proliferation stage of LR. Firstly, a striking reduction of miR-125a was found at 24 h as well as 30 h following partial hepatectomy (PH) in rat liver tissue by miRNAs expression profiles as well as qRT-PCR analysis. Furthermore, in vitro, upregulation of miR-125a decreased proliferation as well as G1/S conversion, which promoted hepatocytes apoptosis. STAT3 was the target of miR-125a. In vivo, upregulation of miR-125a by tail vein injection of agomir inhibited LR index. Upregulation of miR-125a inhibited LR index and hepatocytes proliferation by STAT3/p-STAT3/JUN/BCL2 axis. In summary, these current discoveries indicated that miR-125a inhibited hepatocytes proliferation as well as LR by targeting STAT3 and via acting on the STAT3/p-STAT3/JUN/BCL2 axis.

The Role of JAKs and STAT3 in Regulation of Regenerative-Competent Cells of the Nervous Tissue in β-Amyloid-Induced Neurodegeneration.

We studied the role of JAKs and STAT3 in the growth potential of neural stem cells and the humoral neurotrophic function of neuroglia in modeling β-amyloid-induced neurodegeneration in vitro. It was found that these signaling molecules do not participate in the neural stem cell functioning, and JAKs plays an inhibitory role (realized, however, without STAT3) in the secretion of neurotrophins by glial cells under conditions of their optimal vital activity. The effect of β-amyloid on progenitor cells is accompanied by the appearance of a "negative" effect of STAT3 signaling pathway on their proliferative activity. At the same time, JAKs and STAT3 during neurodegeneration stimulate specialization/differentiation of neural stem cells and production of growth factors by neuroglial cells. These results indicate the possibility of stimulating proliferation of neural stem cells coupled with their differentiation by using selective STAT3 inhibitors.