RESUMO
During neurodegenerative disease, resident CNS macrophages termed "microglia" assume a neuroprotective role and engulf toxic protein aggregates and cell debris. In this issue of Cell, two groups independently show how spleen tyrosine kinase (SYK) acts downstream of microglial surface receptors to propagate this neuroprotective program in vivo.
Assuntos
Microglia , Doenças Neurodegenerativas , Humanos , Microglia/metabolismo , Doenças Neurodegenerativas/metabolismo , Macrófagos , Quinase Syk/metabolismoRESUMO
Genetic studies have highlighted microglia as pivotal in orchestrating Alzheimer's disease (AD). Microglia that adhere to Aß plaques acquire a transcriptional signature, "disease-associated microglia" (DAM), which largely emanates from the TREM2-DAP12 receptor complex that transmits intracellular signals through the protein tyrosine kinase SYK. The human TREM2R47H variant associated with high AD risk fails to activate microglia via SYK. We found that SYK-deficient microglia cannot encase Aß plaques, accelerating brain pathology and behavioral deficits. SYK deficiency impaired the PI3K-AKT-GSK-3ß-mTOR pathway, incapacitating anabolic support required for attaining the DAM profile. However, SYK-deficient microglia proliferated and advanced to an Apoe-expressing prodromal stage of DAM; this pathway relied on the adapter DAP10, which also binds TREM2. Thus, microglial responses to Aß involve non-redundant SYK- and DAP10-pathways. Systemic administration of an antibody against CLEC7A, a receptor that directly activates SYK, rescued microglia activation in mice expressing the TREM2R47H allele, unveiling new options for AD immunotherapy.
Assuntos
Doença de Alzheimer , Microglia , Animais , Camundongos , Humanos , Microglia/metabolismo , Glicogênio Sintase Quinase 3 beta/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Peptídeos beta-Amiloides/metabolismo , Doença de Alzheimer/patologia , Placa Amiloide/metabolismo , Encéfalo/metabolismo , Modelos Animais de Doenças , Quinase Syk/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Receptores Imunológicos/metabolismoRESUMO
Type 1 conventional dendritic (cDC1) cells are necessary for cross-presentation of many viral and tumor antigens to CD8+ T cells. cDC1 cells can be identified in mice and humans by high expression of DNGR-1 (also known as CLEC9A), a receptor that binds dead-cell debris and facilitates XP of corpse-associated antigens. Here, we show that DNGR-1 is a dedicated XP receptor that signals upon ligand engagement to promote phagosomal rupture. This allows escape of phagosomal contents into the cytosol, where they access the endogenous major histocompatibility complex class I antigen processing pathway. The activity of DNGR-1 maps to its signaling domain, which activates SYK and NADPH oxidase to cause phagosomal damage even when spliced into a heterologous receptor and expressed in heterologous cells. Our data reveal the existence of innate immune receptors that couple ligand binding to endocytic vesicle damage to permit MHC class I antigen presentation of exogenous antigens and to regulate adaptive immunity.
Assuntos
Apresentação de Antígeno , Apresentação Cruzada , Células Dendríticas/metabolismo , Lectinas Tipo C/metabolismo , Fagossomos/metabolismo , Receptores Imunológicos/metabolismo , Receptores Mitogênicos/metabolismo , Linfócitos T/metabolismo , Animais , Morte Celular , Técnicas de Cocultura , Células Dendríticas/imunologia , Células HEK293 , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Lectinas Tipo C/genética , Ligantes , Camundongos , NADPH Oxidases/metabolismo , Fagossomos/genética , Fagossomos/imunologia , Fosforilação , Células RAW 264.7 , Espécies Reativas de Oxigênio/metabolismo , Receptores Imunológicos/genética , Receptores Mitogênicos/genética , Transdução de Sinais , Quinase Syk/metabolismo , Linfócitos T/imunologiaRESUMO
Even though SYK and ZAP70 kinases share high sequence homology and serve analogous functions, their expression in B and T cells is strictly segregated throughout evolution. Here, we identified aberrant ZAP70 expression as a common feature in a broad range of B cell malignancies. We validated SYK as the kinase that sets the thresholds for negative selection of autoreactive and premalignant clones. When aberrantly expressed in B cells, ZAP70 competes with SYK at the BCR signalosome and redirects SYK from negative selection to tonic PI3K signaling, thereby promoting B cell survival. In genetic mouse models for B-ALL and B-CLL, conditional expression of Zap70 accelerated disease onset, while genetic deletion impaired malignant transformation. Inducible activation of Zap70 during B cell development compromised negative selection of autoreactive B cells, resulting in pervasive autoantibody production. Strict segregation of the two kinases is critical for normal B cell selection and represents a central safeguard against the development of autoimmune disease and B cell malignancies.
Assuntos
Autoimunidade , Neoplasias/enzimologia , Neoplasias/prevenção & controle , Quinase Syk/metabolismo , Proteína-Tirosina Quinase ZAP-70/metabolismo , Animais , Antígenos CD19/metabolismo , Linfócitos B , Cálcio/metabolismo , Diferenciação Celular , Transformação Celular Neoplásica , Ativação Enzimática , Humanos , Tolerância Imunológica , Linfoma de Células B/enzimologia , Linfoma de Células B/patologia , Camundongos , Modelos Genéticos , Fatores de Transcrição NFATC/metabolismo , Proteínas de Neoplasias , Fosfatidilinositol 3-Quinases/metabolismo , Ligação Proteica , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de SinaisRESUMO
Production of interleukin-17 (IL-17) and IL-22 by T helper 17 (Th17) cells and group 3 innate lymphoid cells (ILC3s) in response to the gut microbiota ensures maintenance of intestinal barrier function. Here, we examined the mechanisms whereby the immune system detects microbiota in the steady state. A Syk-kinase-coupled signaling pathway in dendritic cells (DCs) was critical for commensal-dependent production of IL-17 and IL-22 by CD4+ T cells. The Syk-coupled C-type lectin receptor Mincle detected mucosal-resident commensals in the Peyer's patches (PPs), triggered IL-6 and IL-23p19 expression, and thereby regulated function of intestinal Th17- and IL-17-secreting ILCs. Mice deficient in Mincle or with selective depletion of Syk in CD11c+ cells had impaired production of intestinal RegIIIγ and IgA and increased systemic translocation of gut microbiota. Consequently, Mincle deficiency led to liver inflammation and deregulated lipid metabolism. Thus, sensing of commensals by Mincle and Syk signaling in CD11c+ cells reinforces intestinal immune barrier and promotes host-microbiota mutualism, preventing systemic inflammation.
Assuntos
Células Dendríticas/imunologia , Microbioma Gastrointestinal/imunologia , Interleucina-17/imunologia , Interleucinas/imunologia , Lectinas Tipo C/imunologia , Proteínas de Membrana/imunologia , Quinase Syk/imunologia , Animais , Células Dendríticas/metabolismo , Microbioma Gastrointestinal/fisiologia , Humanos , Interleucina-17/metabolismo , Interleucinas/metabolismo , Mucosa Intestinal/imunologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiologia , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Nódulos Linfáticos Agregados/imunologia , Nódulos Linfáticos Agregados/metabolismo , Nódulos Linfáticos Agregados/microbiologia , Transdução de Sinais/imunologia , Quinase Syk/genética , Quinase Syk/metabolismo , Células Th17/imunologia , Células Th17/metabolismo , Interleucina 22RESUMO
Fungal infection stimulates the canonical C-type lectin receptor (CLR) signaling pathway via activation of the tyrosine kinase Syk. Here we identify a crucial role for the tyrosine phosphatase SHP-2 in mediating CLR-induced activation of Syk. Ablation of the gene encoding SHP-2 (Ptpn11; called 'Shp-2' here) in dendritic cells (DCs) and macrophages impaired Syk-mediated signaling and abrogated the expression of genes encoding pro-inflammatory molecules following fungal stimulation. Mechanistically, SHP-2 operated as a scaffold, facilitating the recruitment of Syk to the CLR dectin-1 or the adaptor FcRγ, through its N-SH2 domain and a previously unrecognized carboxy-terminal immunoreceptor tyrosine-based activation motif (ITAM). We found that DC-derived SHP-2 was crucial for the induction of interleukin 1ß (IL-1ß), IL-6 and IL-23 and anti-fungal responses of the TH17 subset of helper T cells in controlling infection with Candida albicans. Together our data reveal a mechanism by which SHP-2 mediates the activation of Syk in response to fungal infection.
Assuntos
Candidíase/imunologia , Células Dendríticas/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Macrófagos/fisiologia , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Proteínas Tirosina Quinases/metabolismo , Linfócitos T Auxiliares-Indutores/imunologia , Células Th17/imunologia , Motivos de Aminoácidos/genética , Animais , Antígenos de Fungos/imunologia , Células Cultivadas , Citocinas/metabolismo , Ativação Enzimática , Mediadores da Inflamação/metabolismo , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Ativação Linfocitária , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação/genética , Proteína Tirosina Fosfatase não Receptora Tipo 11/genética , Receptores de IgE/genética , Receptores de IgE/metabolismo , Transdução de Sinais , Quinase SykRESUMO
Fungi represent a significant proportion of the gut microbiota. Aberrant immune responses to fungi are frequently observed in inflammatory bowel diseases (IBD) and colorectal cancer (CRC), and mutations in the fungal-sensing pathways are associated with the pathogenesis of IBD. Fungal recognition receptors trigger downstream signaling via the common adaptor protein CARD9 and the kinase SYK. Here we found that commensal gut fungi promoted inflammasome activation during AOM-DSS-induced colitis. Myeloid cell-specific deletion of Card9 or Syk reduced inflammasome activation and interleukin (IL)-18 maturation and increased susceptibility to colitis and CRC. IL-18 promoted epithelial barrier restitution and interferon-γ production by intestinal CD8+ T cells. Supplementation of IL-18 or transfer of wild-type myeloid cells reduced tumor burden in AOM-DSS-treated Card9-/- and Sykfl/flLysMCre/+ mice, whereas treatment with anti-fungal agents exacerbated colitis and CRC. CARD9 deletion changes the gut microbial landscape, suggesting that SYK-CARD9 signaling maintains a microbial ecology that promotes inflammasome activation and thereby restrains colitis and colon tumorigenesis.
Assuntos
Proteínas Adaptadoras de Sinalização CARD/metabolismo , Colite/imunologia , Neoplasias do Colo/imunologia , Fungos/imunologia , Microbioma Gastrointestinal/imunologia , Inflamassomos/metabolismo , Doenças Inflamatórias Intestinais/imunologia , Mucosa Intestinal/fisiologia , Células Mieloides/fisiologia , Quinase Syk/metabolismo , Animais , Proteínas Adaptadoras de Sinalização CARD/genética , Células Cultivadas , Colite/induzido quimicamente , Modelos Animais de Doenças , Humanos , Interleucina-18/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Transdução de Sinais , Dodecilsulfato de Sódio , Quinase Syk/genéticaRESUMO
Positive selection of germinal center (GC) B cells is driven by B cell receptor (BCR) affinity and requires help from follicular T helper cells. The transcription factors c-Myc and Foxo1 are critical for GC B cell selection and survival. However, how different affinity-related signaling events control these transcription factors in a manner that links to selection is unknown. Here we showed that GC B cells reprogram CD40 and BCR signaling to transduce via NF-κB and Foxo1, respectively, whereas naive B cells propagate both signals downstream of either receptor. Although either BCR or CD40 ligation induced c-Myc in naive B cells, both signals were required to highly induce c-Myc, a critical mediator of GC B cell survival and cell cycle reentry. Thus, GC B cells rewire their signaling to enhance selection stringency via a requirement for both antigen receptor- and T cell-mediated signals to induce mediators of positive selection.
Assuntos
Antígenos CD40/fisiologia , Centro Germinativo/imunologia , Proteínas Proto-Oncogênicas c-myc/biossíntese , Receptores de Antígenos de Linfócitos B/fisiologia , Transdução de Sinais/fisiologia , Animais , Proteína Forkhead Box O1/fisiologia , Sistema de Sinalização das MAP Quinases/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , NF-kappa B/fisiologia , Fosfatidilinositol 3-Quinases/fisiologia , Proteínas Proto-Oncogênicas c-akt/fisiologia , Quinase Syk/fisiologiaRESUMO
Haploinsufficiency of the progranulin (PGRN)-encoding gene (GRN) causes frontotemporal lobar degeneration (GRN-FTLD) and results in microglial hyperactivation, TREM2 activation, lysosomal dysfunction, and TDP-43 deposition. To understand the contribution of microglial hyperactivation to pathology, we used genetic and pharmacological approaches to suppress TREM2-dependent transition of microglia from a homeostatic to a disease-associated state. Trem2 deficiency in Grn KO mice reduced microglia hyperactivation. To explore antibody-mediated pharmacological modulation of TREM2-dependent microglial states, we identified antagonistic TREM2 antibodies. Treatment of macrophages from GRN-FTLD patients with these antibodies led to reduced TREM2 signaling due to its enhanced shedding. Furthermore, TREM2 antibody-treated PGRN-deficient microglia derived from human-induced pluripotent stem cells showed reduced microglial hyperactivation, TREM2 signaling, and phagocytic activity, but lysosomal dysfunction was not rescued. Similarly, lysosomal dysfunction, lipid dysregulation, and glucose hypometabolism of Grn KO mice were not rescued by TREM2 ablation. Synaptic loss and neurofilament light-chain (NfL) levels, a biomarker for neurodegeneration, were further elevated in the Grn/Trem2 KO cerebrospinal fluid (CSF). These findings suggest that TREM2-dependent microglia hyperactivation in models of GRN deficiency does not promote neurotoxicity, but rather neuroprotection.
Assuntos
Degeneração Lobar Frontotemporal/patologia , Glicoproteínas de Membrana/metabolismo , Microglia/fisiologia , Monócitos/metabolismo , Progranulinas/deficiência , Receptores Imunológicos/metabolismo , Animais , Anticorpos/imunologia , Anticorpos/farmacologia , Encéfalo/diagnóstico por imagem , Encéfalo/fisiopatologia , Modelos Animais de Doenças , Feminino , Degeneração Lobar Frontotemporal/metabolismo , Humanos , Lisossomos/metabolismo , Lisossomos/patologia , Masculino , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/imunologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/efeitos dos fármacos , Monócitos/efeitos dos fármacos , Receptores Imunológicos/genética , Receptores Imunológicos/imunologia , Quinase Syk/metabolismoRESUMO
The catalytic activity of Zap70 is crucial for T cell antigen receptor (TCR) signaling, but the quantitative and temporal requirements for its function in thymocyte development are not known. Using a chemical-genetic system to selectively and reversibly inhibit Zap70 catalytic activity in a model of synchronized thymic selection, we showed that CD4(+)CD8(+) thymocytes integrate multiple, transient, Zap70-dependent signals over more than 36 h to reach a cumulative threshold for positive selection, whereas 1 h of signaling was sufficient for negative selection. Titration of Zap70 activity resulted in graded reductions in positive and negative selection but did not decrease the cumulative TCR signals integrated by positively selected OT-I cells, which revealed heterogeneity, even among CD4(+)CD8(+) thymocytes expressing identical TCRs undergoing positive selection.
Assuntos
Linfócitos T/fisiologia , Proteína-Tirosina Quinase ZAP-70/fisiologia , Animais , Cálcio/metabolismo , Catálise , Diferenciação Celular , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Proteínas Tirosina Quinases/fisiologia , Receptores de Antígenos de Linfócitos T/fisiologia , Transdução de Sinais , Quinase SykRESUMO
ABSTRACT: Fostamatinib, a recently approved Syk inhibitor used in adult primary immune thrombocytopenia (ITP), has been shown to be safe and effective in this disorder. However, clinical trial results may not be similarly reproduced in clinical practice. Here, 138 patients with ITP (both primary and secondary) from 42 Spanish centers who had been treated with fostamatinib were evaluated prospectively and retrospectively. The median age of our cohort (55.8% women) was 66 years (interquartile range [IQR], 56-80). The median time since ITP diagnosis at fostamatinib initiation was 51 months (IQR, 10-166). The median number of therapies before fostamatinib initiation was 4 (IQR, 2-5), including eltrombopag (76.1%), romiplostim (57.2%), and IV immunoglobulins (44.2%). Fifty-eight patients (42.0%) had signs/symptoms of bleeding in the month before treatment initiation. Seventy-nine percent of patients responded to fostamatinib with 53.6% complete responses (platelet count > 100 × 109/L). Eighty-three patients (60.1%) received fostamatinib monotherapy, achieving a high response rate (85.4%). The proportion of time in response during the 27-month period examined was 83.3%. The median time to platelet response was 11 days (IQR, 7-21). Sixty-seven patients (48.5%) experienced adverse events, mainly grade 1 to 2; the commonest of which were diarrhea (n = 28) and hypertension (n = 21). One patient had deep venous thrombosis, and one patient developed acute myocardial infarction. Fostamatinib was shown to be effective with good safety profile in patients with primary and secondary ITP across a wide age spectrum in this real-world study.
Assuntos
Aminopiridinas , Morfolinas , Oxazinas , Púrpura Trombocitopênica Idiopática , Piridinas , Pirimidinas , Humanos , Feminino , Masculino , Pessoa de Meia-Idade , Púrpura Trombocitopênica Idiopática/tratamento farmacológico , Idoso , Oxazinas/uso terapêutico , Oxazinas/efeitos adversos , Idoso de 80 Anos ou mais , Pirimidinas/uso terapêutico , Pirimidinas/efeitos adversos , Morfolinas/uso terapêutico , Morfolinas/efeitos adversos , Piridinas/uso terapêutico , Piridinas/efeitos adversos , Aminopiridinas/uso terapêutico , Aminopiridinas/efeitos adversos , Estudos Retrospectivos , Resultado do Tratamento , Quinase Syk/antagonistas & inibidores , Inibidores de Proteínas Quinases/uso terapêutico , Inibidores de Proteínas Quinases/efeitos adversos , Contagem de Plaquetas , Estudos ProspectivosRESUMO
Mice carrying a hypomorphic point mutation in the Ptpn6 gene (Ptpn6spin mice) develop an inflammatory skin disease that resembles neutrophilic dermatosis in humans. Here, we demonstrated that interleukin-1α (IL-1α) signaling through IL-1R and MyD88 in both stromal and immune cells drive inflammation in Ptpn6spin mice. We further identified SYK as a critical kinase that phosphorylates MyD88, promoted MyD88-dependent signaling and mediates dermatosis in Ptpn6spin mice. Our studies further demonstrated that SHP1 encoded by Ptpn6 binds and suppresses SYK activation to inhibit MyD88 phosphorylation. Downstream of SHP1 and SYK-dependent counterregulation of MyD88 tyrosine phosphorylation, we have demonstrated that the scaffolding function of receptor interacting protein kinase 1 (RIPK1) and tumor growth factor-ß activated kinase 1 (TAK1)-mediating signaling were required to spur inflammatory disease. Overall, these studies identify SHP1 and SYK crosstalk as a critical regulator of MyD88 post-translational modifications and IL-1-driven inflammation.
Assuntos
Inflamação/imunologia , Interleucina-1alfa/imunologia , Fator 88 de Diferenciação Mieloide/imunologia , Dermatopatias/imunologia , Quinase Syk/imunologia , Animais , Citometria de Fluxo , Células HEK293 , Humanos , Immunoblotting , Inflamação/genética , Inflamação/metabolismo , Interleucina-1alfa/genética , Interleucina-1alfa/metabolismo , MAP Quinase Quinase Quinases/genética , MAP Quinase Quinase Quinases/imunologia , MAP Quinase Quinase Quinases/metabolismo , Camundongos Knockout , Modelos Imunológicos , Mutação , Fator 88 de Diferenciação Mieloide/genética , Fator 88 de Diferenciação Mieloide/metabolismo , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 6/genética , Proteína Tirosina Fosfatase não Receptora Tipo 6/imunologia , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Proteína Serina-Treonina Quinases de Interação com Receptores/genética , Proteína Serina-Treonina Quinases de Interação com Receptores/imunologia , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Receptores de Interleucina-1/imunologia , Receptores de Interleucina-1/metabolismo , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Dermatopatias/genética , Dermatopatias/metabolismo , Quinase Syk/genética , Quinase Syk/metabolismoRESUMO
The transport of Toll-like Receptors (TLRs) to various organelles has emerged as an essential means by which innate immunity is regulated. While most of our knowledge is restricted to regulators that promote the transport of newly synthesized receptors, the regulators that control TLR transport after microbial detection remain unknown. Here, we report that the plasma membrane localized Pattern Recognition Receptor (PRR) CD14 is required for the microbe-induced endocytosis of TLR4. In dendritic cells, this CD14-dependent endocytosis pathway is upregulated upon exposure to inflammatory mediators. We identify the tyrosine kinase Syk and its downstream effector PLCγ2 as important regulators of TLR4 endocytosis and signaling. These data establish that upon microbial detection, an upstream PRR (CD14) controls the trafficking and signaling functions of a downstream PRR (TLR4). This innate immune trafficking cascade illustrates how pathogen detection systems operate to induce both membrane transport and signal transduction.
Assuntos
Endocitose , Receptores de Lipopolissacarídeos/metabolismo , Receptor 4 Toll-Like/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Células Dendríticas/imunologia , Endossomos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Lipopolissacarídeos , Camundongos , Camundongos Endogâmicos C57BL , Fosfolipase C gama/metabolismo , Proteínas Tirosina Quinases/metabolismo , Transdução de Sinais , Quinase SykRESUMO
Cherubism is an autosomal-dominant syndrome characterized by inflammatory destructive bony lesions resulting in symmetrical deformities of the facial bones. Cherubism is caused by mutations in Sh3bp2, the gene that encodes the adaptor protein 3BP2. Most identified mutations in 3BP2 lie within the peptide sequence RSPPDG. A mouse model of cherubism develops hyperactive bone-remodeling osteoclasts and systemic inflammation characterized by expansion of the myelomonocytic lineage. The mechanism by which cherubism mutations alter 3BP2 function has remained obscure. Here we show that Tankyrase, a member of the poly(ADP-ribose)polymerase (PARP) family, regulates 3BP2 stability through ADP-ribosylation and subsequent ubiquitylation by the E3-ubiquitin ligase RNF146 in osteoclasts. Cherubism mutations uncouple 3BP2 from Tankyrase-mediated protein destruction, which results in its stabilization and subsequent hyperactivation of the SRC, SYK, and VAV signaling pathways.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Querubismo/metabolismo , Transdução de Sinais , Tanquirases/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Querubismo/genética , Modelos Animais de Doenças , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Macrófagos/metabolismo , Osteoclastos/metabolismo , Estabilidade Proteica , Proteínas Tirosina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-vav/metabolismo , Deleção de Sequência , Quinase Syk , Tanquirases/genética , Fator de Necrose Tumoral alfa/metabolismo , UbiquitinaçãoRESUMO
Acute respiratory distress syndrome (ARDS) is a deadly clinical presentation in sepsis, COVID, and other lung disorders where vascular fluid leakage is a severe problem. Recent findings by Shadab et al. in the JBC show that a well-known player in immune function, Syk, also regulates vascular leakage in response to sepsis. An existing FDA-approved inhibitor of Syk, fostamatinib, prevents the vascular leakage and improves survival in a mouse sepsis model, providing promise for ARDS treatment in the clinic.
Assuntos
Aminopiridinas , Morfolinas , Inibidores de Proteínas Quinases , Pirimidinas , Síndrome do Desconforto Respiratório , Quinase Syk , Humanos , Aminopiridinas/uso terapêutico , Morfolinas/uso terapêutico , Pirimidinas/uso terapêutico , Quinase Syk/antagonistas & inibidores , Quinase Syk/metabolismo , Síndrome do Desconforto Respiratório/tratamento farmacológico , Animais , Camundongos , Inibidores de Proteínas Quinases/uso terapêutico , Sepse/tratamento farmacológicoRESUMO
Chemical compounds have recently been introduced as alternative and non-integrating inducers of pluripotent stem cell fate. However, chemical reprogramming is hampered by low efficiency and the molecular mechanisms remain poorly characterized. Here, we show that inhibition of spleen tyrosine kinase (Syk) by R406 significantly promotes mouse chemical reprogramming. Mechanistically, R406 alleviates Syk / calcineurin (Cn) / nuclear factor of activated T cells (NFAT) signaling-mediated suppression of glycine, serine, and threonine metabolic genes and dependent metabolites. Syk inhibition upregulates glycine level and downstream transsulfuration cysteine biosynthesis, promoting cysteine metabolism and cellular hydrogen sulfide (H2 S) production. This metabolic rewiring decreased oxidative phosphorylation and ROS levels, enhancing chemical reprogramming. In sum, our study identifies Syk-Cn-NFAT signaling axis as a new barrier of chemical reprogramming and suggests metabolic rewiring and redox homeostasis as important opportunities for controlling cell fates.
Assuntos
Fibroblastos/metabolismo , Sulfeto de Hidrogênio/metabolismo , Quinase Syk/antagonistas & inibidores , Animais , Calcineurina/metabolismo , Células Cultivadas , Cisteína/metabolismo , Fibroblastos/efeitos dos fármacos , Glicina/metabolismo , Camundongos , Fatores de Transcrição NFATC/metabolismo , Oxazinas/farmacologia , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Transdução de SinaisRESUMO
Leishmania spp. are obligate intracellular parasites that must be internalized by phagocytic cells to evade immune responses and cause disease. The uptake of both Leishmania promastigotes (insect-stage parasites) and amastigotes (proliferative-stage parasites in humans and mice) by phagocytes is thought to be mainly host cell driven, not parasite driven. Our previous work indicates that host Src- and Abl-family kinases facilitate Leishmania entry into macrophages and pathogenesis in murine cutaneous leishmaniasis. Here, we demonstrate that host spleen tyrosine kinase (SYK) is required for efficient uptake of Leishmania promastigotes and amastigotes. A Src-family kinase-Abl-family kinase-SYK signaling cascade induces Leishmania amastigote internalization. Finally, lesion size and parasite burden during Leishmania infection is significantly decreased in mice lacking SYK in monocytes or by treatment with the SYK inhibitor entospletinib. In summary, SYK is required for maximal Leishmania uptake by macrophages and disease in mice. Our results suggest potential for treating leishmaniasis using host cell-directed agents.
Assuntos
Leishmania , Leishmaniose , Parasitos , Humanos , Animais , Camundongos , Quinase Syk , Fagocitose , Leishmaniose/parasitologia , MacrófagosRESUMO
The inflammasome adaptor ASC contributes to innate immunity through the activation of caspase-1. Here we found that signaling pathways dependent on the kinases Syk and Jnk were required for the activation of caspase-1 via the ASC-dependent inflammasomes NLRP3 and AIM2. Inhibition of Syk or Jnk abolished the formation of ASC specks without affecting the interaction of ASC with NLRP3. ASC was phosphorylated during inflammasome activation in a Syk- and Jnk-dependent manner, which suggested that Syk and Jnk are upstream of ASC phosphorylation. Moreover, phosphorylation of Tyr144 in mouse ASC was critical for speck formation and caspase-1 activation. Our results suggest that phosphorylation of ASC controls inflammasome activity through the formation of ASC specks.
Assuntos
Proteínas do Citoesqueleto/imunologia , Inflamassomos/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Proteínas Quinases JNK Ativadas por Mitógeno/imunologia , Proteínas Tirosina Quinases/imunologia , Animais , Proteínas Reguladoras de Apoptose , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Proteínas Adaptadoras de Sinalização CARD , Proteínas de Transporte/genética , Proteínas de Transporte/imunologia , Proteínas de Transporte/metabolismo , Caspase 1/imunologia , Caspase 1/metabolismo , Células Cultivadas , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Proteínas de Ligação a DNA , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Feminino , Células HEK293 , Humanos , Immunoblotting , Inflamassomos/genética , Inflamassomos/metabolismo , Interleucina-18/imunologia , Interleucina-18/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/genética , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR , Nigericina/farmacologia , Proteínas Nucleares/genética , Proteínas Nucleares/imunologia , Proteínas Nucleares/metabolismo , Fosforilação/imunologia , Proteínas Tirosina Quinases/genética , Proteínas Tirosina Quinases/metabolismo , Interferência de RNA , Quinase Syk , Tirosina/genética , Tirosina/imunologia , Tirosina/metabolismoRESUMO
Membrane lipids control the cellular activity of kinases containing the Src homology 2 (SH2) domain through direct lipid-SH2 domain interactions. Here we report development of new nonlipidic small molecule inhibitors of the lipid-SH2 domain interaction that block the cellular activity of their host proteins. As a pilot study, we evaluated the efficacy of lipid-SH2 domain interaction inhibitors for spleen tyrosine kinase (Syk), which is implicated in hematopoietic malignancies, including acute myeloid leukemia (AML). An optimized inhibitor (WC36) specifically and potently suppressed oncogenic activities of Syk in AML cell lines and patient-derived AML cells. Unlike ATP-competitive Syk inhibitors, WC36 was refractory to de novo and acquired drug resistance due to its ability to block not only the Syk kinase activity, but also its noncatalytic scaffolding function that is linked to drug resistance. Collectively, our study shows that targeting lipid-protein interaction is a powerful approach to developing new small molecule drugs.
Assuntos
Leucemia Mieloide Aguda , Proteínas Tirosina Quinases , Humanos , Proteínas Tirosina Quinases/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Projetos Piloto , Domínios de Homologia de src , Fosforilação , Leucemia Mieloide Aguda/tratamento farmacológico , Lipídeos , Quinase Syk/metabolismoRESUMO
Epigenetic alterations, especially DNA methylation, have been shown to play a role in the pathogenesis of diabetes mellitus (DM) and its complications, including diabetic kidney disease (DKD). Spleen tyrosine kinase (Syk) is known to be involved in immune and inflammatory disorders. We, therefore, investigated the possible involvement of Syk promoter methylation in DKD, and the mechanisms underlying this process. Kidney tissues were obtained from renal biopsies of patients with early and advanced DKD. A diabetic mouse model (ApoE-/- DM) was generated from ApoE knockout (ApoE-/-) mice using a high-fat and high-glucose diet combined with low-dose streptozocin intraperitoneal injection. We also established an in vitro model using HK2 cells. A marked elevation in the expression levels of Syk, PKCß, and P66shc in renal tubules was observed in patients with DKD. In ApoE-/- DM mice, Syk expression and the binding of Sp1 to the Syk gene promoter were both increased in the kidney. In addition, the promoter region of the Syk gene exhibited hypomethylation. Syk inhibitor (R788) intervention improved renal function and alleviated pathologic changes in ApoE-/- DM mice. Moreover, R788 intervention alleviated oxidative stress and apoptosis and downregulated the expression of PKCß/P66shc signaling pathway proteins. In HK2 cells, oxLDL combined with high-glucose stimulation upregulated Sp1 expression in the nucleus (compared with control and oxLDL groups), and this was accompanied by an increase in the binding of Sp1 to the Syk gene promoter. SP1 silencing downregulated the expression of Syk and inhibited the production of reactive oxygen species and cell apoptosis. Finally, PKC agonist intervention reversed the oxidative stress and apoptosis induced by Syk inhibitor (R406). In DKD, hypomethylation at the Syk gene promoter was accompanied by an increase in Sp1 binding at the promoter. As a consequence of this enhanced Sp1 binding, Syk gene expression was upregulated. Syk inhibitors could attenuate DKD-associated oxidative stress and apoptosis via downregulation of PKCß/P66shc signaling pathway proteins. Together, our results identify Syk as a promising target for intervention in DKD.