Project description:Combining metabolomics analyses with an IFN-stimulated response elements reporter system, we identify spermine as a cellular metabolite brake for JAK1 signaling. Spermine directly binds to FERM and SH2 domains of JAK1 to impair IFNAR2-JAK1 interaction. Spermine suppresses JAK1 phosphorylation triggered by types I and II cytokines, including IFN-I/II, IL-2, and IL-6. Spermine treatment attenuates autoimmune pathogenesis in a SLE murine model and reduces IFN-I signaling in monocytes from SLE patients, which have reduced spermine levels.
Project description:Combining metabolomics analyses with an IFN-stimulated response elements reporter system, we identify spermine as a cellular metabolite brake for JAK1 signaling. Spermine directly binds to FERM and SH2 domains of JAK1 to impair IFNAR2-JAK1 interaction. Spermine suppresses JAK1 phosphorylation triggered by types I and II cytokines, including IFN-I/II, IL-2, and IL-6. Spermine treatment attenuates autoimmune pathogenesis in a SLE murine model and reduces IFN-I signaling in monocytes from SLE patients, which have reduced spermine levels.
Project description:Using an unbiased metabolomics approach and a IFN-stimulated response elements (ISRE) reporter screening system, we have identified the cellular metabolite spermine as an endogenous brake restraining IFN-I signaling and autoinflammation. Cellular spermine concentration decrease upon stimulations with IFN-I, IL-2, and IL-6. Spermine suppresses phosphorylation of JAK1 in macrophages responding to IFN-I, T cells responding to IL-2, and fibroblasts responding to IL-6. Mechanistically, spermine binds directly to the N-terminal domains of JAK1, resulting in impaired IFNAR2-JAK1 interaction required for initiating downstream signaling and, subsequently, restrained IFN-I effector response. Moreover, spermine attenuates SLE progression in an SLE murine model and reduces IFN-I signaling in PBMCs from SLE patients.
Project description:Whole blood samples from SLE patients were collected and PBMCs were isolated using Ficoll-PaqueTM PLUS reagent according to the manufacturer’s protocol. The fresh isolated PBMCs from SLE individuals were treated with DMSO or spermine for 3h, PBMCs from healthy control were used as control, then samples were harvested and lysated with Trizol reagend for RNA-sequencing analysis.
Project description:Cytokine receptors respond to circulating inflammatory cytokines by signaling through Janus kinases (JAK) to ultimately elicit phosphorylation-dependent nuclear translocation and transcriptional activity of signal transducer and activator of transcription (STAT) proteins. JAK1 is particularly important for STAT3-dependent cytokine production and macrophage recruitment by cardiomyocytes, however the role of basal JAK1 signaling in cardiac homeostasis remains unclear. Downstream signaling through STAT3 promotes cardiac hypertrophy and remodeling in response to pressure overload or angiotensin-II but is protective during ischemic injury. To assess the roles of JAK1 in cardiac physiology we generated mice with cardiomyocyte-specific deletion of JAK1 and evaluated cardiac structure and function, myocardial remodeling, and intracellular signal transduction. Loss of JAK1 in cardiomyocytes results in dilated cardiomyopathy by 6 months of age, indicating cytokine receptor signaling through JAK1 is essential for cardiac physiology. Cardiomyopathy in aged mice lacking cardiomyocyte JAK1 was characterized by substantial myocardial fibrosis. Transcriptomics and gene expression analyses identified JAK1-dependent cytokine-inducible target genes in adult cardiomyocytes. JAK1-deficient cardiomyocytes were resistant to phosphorylation and nuclear translocation of STAT3 and transcriptional reprogramming in response to the cytokine oncostatin M. Collectively these data indicate cardiomyocyte JAK1 kinase activity is required for proper cardiac maturation and homeostasis and is indispensable for STAT3 activation by oncostatin M.
Project description:The JAK family of non-receptor tyrosine kinases includes four subtypes (JAK1, JAK2, JAK3, and TYK2) and is responsible for signal transduction downstream of diverse cytokine receptors. JAK inhibitors have emerged as important therapies for immuno(onc)ological disorders, but their use is limited by undesirable side effects presumed to arise from poor subtype selectivity, a common challenge for inhibitors targeting the ATP-binding pocket of kinases. Here, we describe the chemical proteomic discovery of a druggable allosteric cysteine present in the non-catalytic pseudokinase domain of JAK1 (C817) and TYK2 (C838), but absent from JAK2 or JAK3. Electrophilic compounds selectively engaging this site block JAK1-dependent transphosphorylation and cytokine signaling, while appearing to act largely as “silent” ligands for TYK2. Importantly, the allosteric JAK1 inhibitors do not impair JAK2-dependent cytokine signaling and are inactive in cells expressing a C817A JAK1 mutant. Our findings thus reveal an allosteric approach for inhibiting JAK1 with unprecedented subtype selectivity.
Project description:Aberrant signal transduction contributes substantially to leukemogenesis. The Janus kinase 1 (JAK1) gene encodes a cytoplasmic tyrosine kinase that noncovalently associates with a variety of cytokine receptors and plays a nonredundant role in lymphoid cell precursor proliferation, survival, and differentiation. Somatic mutations in JAK1 occur in individuals with acute lymphoblastic leukemia (ALL). JAK1 mutations were more prevalent among adult subjects with the T cell precursor ALL, where they accounted for 18% of cases, and were associated with advanced age at diagnosis, poor response to therapy, and overall prognosis; We used microarray to compare the gene expression profile of JAK1 mutation positive or negative ALL blasts Experiment Overall Design: Thawed or freshly isolated T-ALL cells (>90% blasts) were homogenized, total RNA was extracted and hybridized on Affymetrix microarrays