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: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
Project description:Inhibition of Janus kinase (JAK) family enzymes has surged as a popular strategy for treating inflammatory and autoimmune skin diseases. In the clinic, current available small molecule JAK inhibitors show distinct efficacy and safety profiles, likely reflecting their variable selectivity for JAK subtypes. Nonselective inhibition of multiple JAK enzymes is associated with increased side effects and has resulted in FDA-mandated black box warnings. Developing therapeutics to enable absolute JAK subtype selectivity is challenging and has not yet been achieved. Here, we harness RNA interference (RNAi) for rationally designing small interfering RNA (siRNA) therapeutics that offer sequence-specific gene silencing of JAK1, thus narrowing the spectrum of action on JAK-dependent cytokine signaling pathways to maintain efficacy and improve safety. We developed a fully chemically modified siRNA that supports efficient silencing of JAK1 expression in human skin explant and functional modulation of JAK1-dependent inflammatory signaling. A single injection of the JAK1 siRNA into mouse skin enables JAK1 silencing for 5 weeks in vivo. In a mouse model of vitiligo, local administration of the JAK1 siRNA significantly reduces skin infiltration of autoreactive CD8+ T cells and prevents epidermal depigmentation. This work outlines a robust framework for designing targeted RNAi-based therapies and establishes a path toward novel siRNA treatments for inflammatory and autoimmune skin diseases.