RESUMO
Gene expression is regulated by the rates of synthesis and degradation of mRNAs, but how these processes are coordinated is poorly understood. Here, we show that reduced transcription dynamics of specific genes leads to enhanced m6A deposition, preferential activity of the CCR4-Not complex, shortened poly(A) tails, and reduced stability of the respective mRNAs. These effects are also exerted by internal ribosome entry site (IRES) elements, which we found to be transcriptional pause sites. However, when transcription dynamics, and subsequently poly(A) tails, are globally altered, cells buffer mRNA levels by adjusting the expression of mRNA degradation machinery. Stress-provoked global impediment of transcription elongation leads to a dramatic inhibition of the mRNA degradation machinery and massive mRNA stabilization. Accordingly, globally enhanced transcription, such as following B cell activation or glucose stimulation, has the opposite effects. This study uncovers two molecular pathways that maintain balanced gene expression in mammalian cells by linking transcription to mRNA stability.
Assuntos
Poli A/genética , RNA Mensageiro/metabolismo , Transcrição Gênica , Adenosina/análogos & derivados , Animais , Linfócitos B/fisiologia , Células Cultivadas , Feminino , Regulação da Expressão Gênica , Humanos , Sítios Internos de Entrada Ribossomal , Células MCF-7 , Camundongos Endogâmicos C57BL , Membro 2 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Membro 2 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Poli A/metabolismo , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Estabilidade de RNA , RNA Mensageiro/genética , Receptores CCR4/genética , Receptores CCR4/metabolismoRESUMO
Hematopoietic stem and progenitor cells (HSPCs) are a small population of undifferentiated cells that have the capacity for self-renewal and differentiate into all blood cell lineages. These cells are the most useful cells for clinical transplantations and for regenerative medicine. So far, it has not been possible to expand adult hematopoietic stem cells (HSCs) without losing their self-renewal properties. CD74 is a cell surface receptor for the cytokine macrophage migration inhibitory factor (MIF), and its mRNA is known to be expressed in HSCs. Here, we demonstrate that mice lacking CD74 exhibit an accumulation of HSCs in the bone marrow (BM) due to their increased potential to repopulate and compete for BM niches. Our results suggest that CD74 regulates the maintenance of the HSCs and CD18 expression. Its absence leads to induced survival of these cells and accumulation of quiescent and proliferating cells. Furthermore, in in vitro experiments, blocking of CD74 elevated the numbers of HSPCs. Thus, we suggest that blocking CD74 could lead to improved clinical insight into BM transplant protocols, enabling improved engraftment.
Assuntos
Antígenos de Diferenciação de Linfócitos B/genética , Antígenos de Diferenciação de Linfócitos B/metabolismo , Células-Tronco Hematopoéticas/metabolismo , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/metabolismo , Adulto , Animais , Células da Medula Óssea/metabolismo , Transplante de Medula Óssea/métodos , Linhagem da Célula , Feminino , Voluntários Saudáveis , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/fisiologia , Humanos , Oxirredutases Intramoleculares/metabolismo , Fatores Inibidores da Migração de Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Transdução de SinaisRESUMO
SLAMF9 belongs to the conserved lymphocytic activation molecule family (SLAMF). Unlike other SLAMs, which have been extensively studied, the role of SLAMF9 in the immune system remained mostly unexplored. By generating CRISPR/Cas9 SLAMF9 knockout mice, we analyzed the role of this receptor in plasmacytoid dendritic cells (pDCs), which preferentially express the SLAMF9 transcript and protein. These cells display a unique capacity to produce type I IFN and bridge between innate and adaptive immune response. Analysis of pDCs in SLAMF9-/- mice revealed an increase of immature pDCs in the bone marrow and enhanced accumulation of pDCs in the lymph nodes. In the periphery, SLAMF9 deficiency resulted in lower levels of the transcription factor SpiB, elevation of pDC survival, and attenuated IFN-α and TNF-α production. To define the role of SLAMF9 during inflammation, pDCs lacking SLAMF9 were followed during induced experimental autoimmune encephalomyelitis. SLAMF9-/- mice demonstrated attenuated disease and delayed onset, accompanied by a prominent increase of immature pDCs in the lymph node, with a reduced costimulatory potential and enhanced infiltration of pDCs into the central nervous system. These results suggest the crucial role of SLAMF9 in pDC differentiation, homeostasis, and function in the steady state and during experimental autoimmune encephalomyelitis.
Assuntos
Células Dendríticas/metabolismo , Doença , Saúde , Homeostase , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Animais , Medula Óssea/metabolismo , Diferenciação Celular , Regulação da Expressão Gênica , Linfonodos/metabolismo , Ativação Linfocitária/imunologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores CCR5/metabolismo , Família de Moléculas de Sinalização da Ativação Linfocitária/deficiência , Transcriptoma/genéticaRESUMO
Multiple sclerosis is an inflammatory disease of the CNS characterized by neurologic impairment resulting from primary demyelination and axonal damage. The pathogenic mechanisms of disease development include Ag-specific T cell activation and Th1 differentiation, followed by T cell and macrophage migration into the CNS. CCL2 is a chemokine that induces migration of monocytes, memory T cells, and dendritic cells. We previously demonstrated that picomolar levels of CCL2 strongly restrict the development of inflammation in models of inflammatory bowel disease. Moreover, CCR2 deficiency in T cells promotes a program inducing the accumulation of Foxp3+ regulatory T cells while decreasing the levels of Th17 cells in vivo. In the current study, the effect of picomolar levels of CCL2 on the autoimmune inflammatory response associated with a multiple sclerosis-like disease in mice was analyzed. We found that low dosages of CCL2 were effective in suppressing MOG-induced experimental autoimmune encephalomyelitis (EAE), and they downregulated chronic EAE. The modulation of EAE by CCL2 was associated with downregulation of Th1/Th17 cells and upregulation of TGF-ß and induction of regulatory CD4+Foxp3 T cells. Most strikingly, these low levels of CCL2 induced formation of highly functional regulatory T cells. Thus, this study strongly supports the potential use of CCL2 as a regulatory mediator for treating inflammatory autoimmune diseases.
Assuntos
Quimiocina CCL2/imunologia , Regulação para Baixo/imunologia , Encefalomielite Autoimune Experimental/imunologia , Memória Imunológica , Esclerose Múltipla/imunologia , Células Th17/imunologia , Animais , Doença Crônica , Encefalomielite Autoimune Experimental/patologia , Feminino , Camundongos , Esclerose Múltipla/patologia , Linfócitos T Reguladores/patologia , Células Th17/patologia , Fator de Crescimento Transformador beta/imunologiaRESUMO
CD74 is a cell-surface receptor for the cytokine macrophage migration inhibitory factor. Macrophage migration inhibitory factor binding to CD74 induces its intramembrane cleavage and the release of its cytosolic intracellular domain (CD74-ICD), which regulates cell survival. In the present study, we characterized the transcriptional activity of CD74-ICD in chronic lymphocytic B cells. We show that following CD74 activation, CD74-ICD interacts with the transcription factors RUNX (Runt related transcription factor) and NF-κB and binds to proximal and distal regulatory sites enriched for genes involved in apoptosis, immune response, and cell migration. This process leads to regulation of expression of these genes. Our results suggest that identifying targets of CD74 will help in understanding of essential pathways regulating B-cell survival in health and disease.
RESUMO
Chemokines and chemokine receptors establish a complex network modulating immune cell migration and localization. These molecules were also suggested to mediate the differentiation of leukocytes; however, their intrinsic, direct regulation of lymphocyte fate remained unclear. CCR2 is the main chemokine receptor inducing macrophage and monocyte recruitment to sites of inflammation, and it is also expressed on T cells. To assess whether CCR2 directly regulates T cell responses, we followed the fates of CCR2-/- T cells in T cell-specific inflammatory models. Our in vitro and in vivo results show that CCR2 intrinsically mediates the expression of inflammatory T cell cytokines, and its absence on T cells results in attenuated colitis progression. Moreover, CCR2 deficiency in T cells promoted a program inducing the accumulation of Foxp3+ regulatory T cells, while decreasing the levels of Th17 cells in vivo, indicating that CCR2 regulates the immune response by modulating the effector/regulatory T ratio.
Assuntos
Imunidade Celular , Receptores CCR2/metabolismo , Linfócitos T Reguladores/imunologia , Animais , Movimento Celular , Colite/imunologia , Citocinas/genética , Citocinas/imunologia , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica , Macrófagos/imunologia , Camundongos , Receptores CCR2/deficiência , Receptores CCR2/genética , Receptores CCR2/imunologia , Receptores CCR5/imunologia , Receptores CCR5/metabolismo , Células Th17/imunologia , Células Th17/fisiologiaRESUMO
The control of lymphoid homeostasis is the result of a very fine balance between lymphocyte production, proliferation, and apoptosis. In this study, we focused on the role of T cells in the maintenance/survival of the mature naive peripheral B cell population. We show that naive B and T cells interact via the signaling lymphocyte activation molecule (SLAM) family receptor, SLAMF6. This interaction induces cell type-specific signals in both cell types, mediated by the SLAM-associated protein (SAP) family of adaptors. This signaling results in an upregulation of the expression of the cytokine migration inhibitory factor in the T cells and augmented expression of its receptor CD74 on the B cell counterparts, consequently enhancing B cell survival. Furthermore, in X-linked lymphoproliferative disease patients, SAP deficiency reduces CD74 expression, resulting in the perturbation of B cell maintenance from the naive stage. Thus, naive T cells regulate B cell survival in a SLAMF6- and SAP-dependent manner.
Assuntos
Subpopulações de Linfócitos B/fisiologia , Linfócitos B/fisiologia , Células Sanguíneas/fisiologia , Transtornos Linfoproliferativos/imunologia , Proteína Associada à Molécula de Sinalização da Ativação Linfocitária/metabolismo , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Linfócitos T/fisiologia , Animais , Anticorpos Bloqueadores/administração & dosagem , Comunicação Celular , Diferenciação Celular , Proliferação de Células , Sobrevivência Celular , Células Cultivadas , Homeostase , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , RNA Interferente Pequeno/genética , Proteína Associada à Molécula de Sinalização da Ativação Linfocitária/genética , Família de Moléculas de Sinalização da Ativação Linfocitária/genéticaRESUMO
The transformation of normal to malignant cells is accompanied by substantial changes in gene expression programs through diverse mechanisms. Here, we examined the changes in the landscape of transcription start sites and alternative promoter (AP) usage and their impact on the translatome in TCL1-driven chronic lymphocytic leukemia (CLL). Our findings revealed a marked elevation of APs in CLL B cells from Eµ-Tcl1 transgenic mice, which are particularly enriched with intra-genic promoters that generate N-terminally truncated or modified proteins. Intra-genic promoter activation is mediated by (1) loss of function of 'closed chromatin' epigenetic regulators due to the generation of inactive N-terminally modified isoforms or reduced expression; (2) upregulation of transcription factors, including c-Myc, targeting the intra-genic promoters and their associated enhancers. Exogenous expression of Tcl1 in MEFs is sufficient to induce intra-genic promoters of epigenetic regulators and promote c-Myc expression. We further found a dramatic translation downregulation of transcripts bearing CNY cap-proximal trinucleotides, reminiscent of cells undergoing metabolic stress. These findings uncovered the role of Tcl1 oncogenic function in altering promoter usage and mRNA translation in leukemogenesis.
Assuntos
Leucemia Linfocítica Crônica de Células B , Animais , Carcinogênese/genética , Epigênese Genética , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/patologia , Camundongos , Camundongos Transgênicos , Polirribossomos/metabolismo , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismoRESUMO
CD74 is receptor for the cytokine macrophage migration inhibitory factor (MIF). MIF binding to CD74 induces a signaling cascade resulting in the release of its cytosolic intracellular domain (CD74-ICD) that serves as a transcriptional regulator in chronic lymphocytic leukemia (CLL) cells. In the current study, we investigated the transcriptional and regulatory function of CD74-ICD in normal B cells. We show that following activation, CD74-ICD forms a complex in the cytosol with transcription factors, like PAX5, and binds the chromatin at a significantly higher number of sites compared with its binding in CLL cells. The expression of a major portion of these bound genes is shut down in the malignant cells. The CD74-ICD:PAX5 complex binds the promoter areas of a tumor-suppressor gene, DMTF1, and downregulates its expression through inhibition of transcription. These findings can help identify novel therapeutic pathways that are regulated during oncogenic transformation and are targets for future treatments.
Assuntos
Linfócitos B , Leucemia Linfocítica Crônica de Células B , Humanos , Antígenos de Histocompatibilidade Classe II/metabolismo , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/patologia , Ligação Proteica , Transdução de Sinais , Fatores de Transcrição/metabolismo , Transcrição GênicaRESUMO
B cells have essential functions in multiple sclerosis and in its mouse model, experimental autoimmune encephalomyelitis, both as drivers and suppressors of the disease. The suppressive effects are driven by a regulatory B cell (Breg) population that functions, primarily but not exclusively, via the production of IL-10. However, the mechanisms modulating IL-10-producing Breg abundance are poorly understood. Here we identify SLAMF5 for controlling IL-10+ Breg maintenance and function. In EAE, the deficiency of SLAMF5 in B cells causes accumulation of IL10+ Bregs in the central nervous system and periphery. Blocking SLAMF5 in vitro induces both human and mouse IL-10-producing Breg cells and increases their survival with a concomitant increase of a transcription factor, c-Maf. Finally, in vivo SLAMF5 blocking in EAE elevates IL-10+ Breg levels and ameliorates disease severity. Our results suggest that SLAMF5 is a negative moderator of IL-10+ Breg cells, and may serve as a therapeutic target in MS and other autoimmune diseases.
Assuntos
Linfócitos B Reguladores/imunologia , Encefalomielite Autoimune Experimental/patologia , Interleucina-10/imunologia , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Animais , Sobrevivência Celular/imunologia , Células Cultivadas , Modelos Animais de Doenças , Encefalomielite Autoimune Experimental/imunologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Esclerose Múltipla/imunologia , Família de Moléculas de Sinalização da Ativação Linfocitária/antagonistas & inibidores , Família de Moléculas de Sinalização da Ativação Linfocitária/genéticaRESUMO
Multiple myeloma (MM) is characterized by an accumulation of malignant plasma cells (PCs) within the BM. The BM microenvironment supports survival of the malignant cells and is composed of cellular fractions that foster myeloma development and progression by suppression of the immune response. Despite major progress in understanding the biology and pathophysiology of MM, this disease is still incurable and requires aggressive treatment with significant side effects. CD84 is a self-binding immunoreceptor belonging to the signaling lymphocyte activation molecule (SLAM) family. Previously, we showed that CD84 bridges between chronic lymphocytic leukemia cells and their microenvironment, and it regulates T cell function. In the current study, we investigated the role of CD84 in MM. Our results show that MM cells express low levels of CD84. However, these cells secrete the cytokine macrophage migration inhibitory factor (MIF), which induces CD84 expression on cells in their microenvironment. Its activation leads to an elevation of expression of genes regulating differentiation to monocytic/granulocytic-myeloid-derived suppressor cells (M-MDSCs and G-MDSCs, respectively) and upregulation of PD-L1 expression on MDSCs, which together suppress T cell function. Downregulation of CD84 or its blocking reduce MDSC accumulation, resulting in elevated T cell activity and reduced tumor load. Our data suggest that CD84 might serve as a novel therapeutic target in MM.
Assuntos
Mieloma Múltiplo/imunologia , Família de Moléculas de Sinalização da Ativação Linfocitária/genética , Família de Moléculas de Sinalização da Ativação Linfocitária/imunologia , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Microambiente Tumoral/imunologia , Animais , Antígeno B7-H1 , Linhagem Celular Tumoral , Humanos , Imunoterapia , Oxirredutases Intramoleculares/metabolismo , Leucemia Linfocítica Crônica de Células B/imunologia , Ativação Linfocitária , Fatores Inibidores da Migração de Macrófagos/metabolismo , Camundongos , Mieloma Múltiplo/terapia , Células Supressoras Mieloides/imunologia , Linfócitos T/imunologiaRESUMO
Wiskott-Aldrich syndrome protein (WASp) is essential for optimal T cell activation. Patients with WAS exhibit both immunodeficiency and a marked susceptibility to systemic autoimmunity. We investigated whether alterations in Treg function might explain these paradoxical observations. While WASp-deficient (WASp(-/-)) mice exhibited normal thymic Treg generation, the competitive fitness of peripheral Tregs was severely compromised. The total percentage of forkhead box P3-positive (Foxp3(+)) Tregs among CD4(+) T cells was reduced, and WASp(-/-) Tregs were rapidly outcompeted by WASp(+) Tregs in vivo. These findings correlated with reduced expression of markers associated with self-antigen-driven peripheral Treg activation and homing to inflamed tissue. Consistent with these findings, WASp(-/-) Tregs showed a reduced ability to control aberrant T cell activation and autoimmune pathology in Foxp3(-/-)Scurfy (sf) mice. Finally, WASp(+) Tregs exhibited a marked selective advantage in vivo in a WAS patient with a spontaneous revertant mutation, indicating that altered Treg fitness likely explains the autoimmune features in human WAS.
Assuntos
Linfócitos T Reguladores/imunologia , Proteína da Síndrome de Wiskott-Aldrich/imunologia , Transferência Adotiva , Animais , Autoimunidade , Diferenciação Celular , Feminino , Fatores de Transcrição Forkhead/deficiência , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/imunologia , Homeostase , Humanos , Técnicas In Vitro , Ativação Linfocitária , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Mutantes , Mutação , Transdução de Sinais , Linfócitos T Reguladores/patologia , Síndrome de Wiskott-Aldrich/genética , Síndrome de Wiskott-Aldrich/imunologia , Síndrome de Wiskott-Aldrich/patologia , Proteína da Síndrome de Wiskott-Aldrich/deficiência , Proteína da Síndrome de Wiskott-Aldrich/genéticaRESUMO
To more precisely identify the B-cell phenotype in Wiskott-Aldrich syndrome (WAS), we used 3 distinct murine in vivo models to define the cell intrinsic requirements for WAS protein (WASp) in central versus peripheral B-cell development. Whereas WASp is dispensable for early bone marrow B-cell development, WASp deficiency results in a marked reduction in each of the major mature peripheral B-cell subsets, exerting the greatest impact on marginal zone and B1a B cells. Using in vivo bromodeoxyuridine labeling and in vitro functional assays, we show that these deficits reflect altered peripheral homeostasis, partially resulting from an impairment in integrin function, rather than a developmental defect. Consistent with these observations, we also show that: (1) WASp expression levels increase with cell maturity, peaking in those subsets exhibiting the greatest sensitivity to WASp deficiency; (2) WASp(+) murine B cells exhibit a marked selective advantage beginning at the late transitional B-cell stage; and (3) a similar in vivo selective advantage is manifest by mature WASp(+) human B cells. Together, our data provide a better understanding of the clinical phenotype of WAS and suggest that gene therapy might be a useful approach to rescue altered B-cell homeostasis in this disease.
Assuntos
Subpopulações de Linfócitos B/imunologia , Células da Medula Óssea/imunologia , Homeostase/imunologia , Proteína da Síndrome de Wiskott-Aldrich/imunologia , Animais , Homeostase/genética , Camundongos , Camundongos Knockout , Proteína da Síndrome de Wiskott-Aldrich/genéticaRESUMO
Imatinib is a receptor tyrosine kinase inhibitor that blocks the activity of c-Abl, c-Kit, and PDGF receptors. We tested the protective effects of imatinib in thymic stromal lymphopoietin transgenic mice, a model of cryoglobulinemia and associated membranoproliferative glomerulonephritis (MPGN), in which some glomerular manifestations likely result from PDGF receptor activation. Surprising, administration of imatinib beginning at weaning suppressed production of cryoglobulin, attenuating both the renal injury and systemic features of cryoglobulinemia. Flow cytometry suggested that inhibition of B cell development in the bone marrow likely caused the reduction in cryoglobulin production. In addition, administration of imatinib to thymic stromal lymphopoietin transgenic mice with established MPGN also diminished cryoglobulin production and reversed the renal and systemic lesions. These data suggest that treatment with imatinib may be a novel therapeutic approach for cryoglobulinemia and MPGN in humans.
Assuntos
Crioglobulinemia/tratamento farmacológico , Glomerulonefrite Membranoproliferativa/tratamento farmacológico , Piperazinas/uso terapêutico , Inibidores de Proteínas Quinases/uso terapêutico , Pirimidinas/uso terapêutico , Animais , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Benzamidas , Complemento C3/metabolismo , Crioglobulinemia/imunologia , Citocinas/sangue , Citocinas/genética , Citocinas/fisiologia , Feminino , Glomerulonefrite Membranoproliferativa/imunologia , Mesilato de Imatinib , Ativação Linfocitária/efeitos dos fármacos , Masculino , Camundongos , Camundongos Transgênicos , Linfopoietina do Estroma do TimoRESUMO
Chronic lymphocytic leukemia (CLL) is a malignancy of mature B lymphocytes. The microenvironment of the CLL cells is a vital element in the regulation of the survival of these malignant cells. CLL cell longevity is dependent on external signals, originating from cells in their microenvironment including secreted and surface-bound factors. Dendritic cells (DCs) play an important part in tumor microenvironment, but their role in the CLL bone marrow (BM) niche has not been studied. We show here that CLL cells induce accumulation of bone marrow dendritic cells (BMDCs). Depletion of this population attenuates disease expansion. Our results show that the support of the microenvironment is partly dependent on CD84, a cell surface molecule belonging to the Signaling Lymphocyte Activating Molecule (SLAM) family of immunoreceptors. Our results suggest a novel therapeutic strategy whereby eliminating BMDCs or blocking the CD84 expressed on these cells may reduce the tumor load.
Assuntos
Medula Óssea/patologia , Células Dendríticas/patologia , Leucemia Linfocítica Crônica de Células B/patologia , Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismo , Microambiente Tumoral/imunologia , Animais , Apoptose , Medula Óssea/imunologia , Medula Óssea/metabolismo , Proliferação de Células , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Feminino , Humanos , Leucemia Linfocítica Crônica de Células B/imunologia , Leucemia Linfocítica Crônica de Células B/metabolismo , Camundongos , Camundongos Transgênicos , Prognóstico , Células Tumorais CultivadasRESUMO
Quite a few regulatory proteins, including transcription factors, are normally maintained in a dormant state to be activated after internal or environmental cues. Recently, a novel strategy, requiring proteolytic cleavage, was described for the mobilization of dormant transcription factors. These transcription factors are initially synthesized in an inactive form, whereas "nesting" in integral membrane precursor proteins. After a cleavage event, these new active factors are released from the membrane and can migrate into the nucleus to drive regulated gene transcription. This mechanism, regulated intramembrane proteolysis (RIP), controls diverse biological processes in prokaryotes and eukaryotes in response to a variety of signals. The MHC class II chaperone, CD74 (invariant chain, Ii), was previously shown to function as a signaling molecule in several pathways. Recently, we demonstrated that after intramembranal cleavage, the CD74 cytosolic fragment (CD74-ICD) is released and induces activation of transcription mediated by the NF-kappaB p65/RelA homodimer and the B-cell-enriched coactivator, TAF(II)105. Here, we add CD74 to the growing family of RIP-processed proteins. Our studies show that CD74 ectodomain must be processed in the endocytic compartments to allow its intramembrane cleavage that liberates CD74 intracellular domain (CD74-ICD). We demonstrate that CD74-ICD translocates to the nucleus and induces the activation of the p65 member of NF-kappaB in this compartment.
Assuntos
Antígenos de Diferenciação de Linfócitos B/metabolismo , Linfócitos B/citologia , Linfócitos B/fisiologia , Membrana Celular/metabolismo , Antígenos de Histocompatibilidade Classe II/metabolismo , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Humanos , Proteínas de Membrana , Camundongos , NF-kappa B/metabolismo , Baço , Fator de Transcrição RelA , Fatores de Transcrição , Ativação Transcricional , TransfecçãoRESUMO
Chronic lymphocytic leukemia (CLL) is characterized by clonal proliferation and progressive accumulation of mature B lymphocytes in the peripheral blood, lymphoid tissues, and bone marrow. CLL is characterized by profound immune defects leading to severe infectious complications. T cells are numerically, phenotypically, and functionally highly abnormal in CLL, with only limited ability to exert antitumor immune responses. Exhaustion of T cells has also been suggested to play an important role in antitumor responses. CLL-mediated T cell exhaustion is achieved by the aberrant expression of several inhibitory molecules on CLL cells and their microenvironment, prominently the programmed cell death ligand 1/programmed cell death 1 (PD-L1/PD-1) receptors. Previously, we showed that CD84, a member of the SLAM family of receptors, bridges between CLL cells and their microenvironment. In the current study, we followed CD84 regulation of T cell function. We showed that cell-cell interaction mediated through human and mouse CD84 upregulates PD-L1 expression on CLL cells and in their microenvironment and PD-1 expression on T cells. This resulted in suppression of T cell responses and activity in vitro and in vivo. Thus, our results demonstrate a role for CD84 in the regulation of immune checkpoints by leukemia cells and identify CD84 blockade as a therapeutic strategy to reverse tumor-induced immune suppression.
Assuntos
Antígeno B7-H1/imunologia , Regulação Leucêmica da Expressão Gênica/imunologia , Leucemia Linfocítica Crônica de Células B/imunologia , Proteínas de Neoplasias/imunologia , Receptor de Morte Celular Programada 1/imunologia , Família de Moléculas de Sinalização da Ativação Linfocitária/imunologia , Animais , Antígeno B7-H1/genética , Regulação Leucêmica da Expressão Gênica/genética , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/patologia , Camundongos , Camundongos Knockout , Proteínas de Neoplasias/genética , Receptor de Morte Celular Programada 1/genética , Família de Moléculas de Sinalização da Ativação Linfocitária/genéticaRESUMO
The continuous recirculation of mature lymphocytes and their entry into the peripheral lymph nodes are crucial for the development of an immune response to foreign antigens. Occasionally, the entry and the subsequent response of T lymphocytes in these sites lead to severe inflammation and pathological conditions. Here, we characterized the tetraspanin molecule, CD151, as a regulator of T cell motility in health and in models of inflammatory bowel disease. CD151 formed a cell surface complex with VLA-4 and LFA-1 integrins, and its activation led to enhanced migration of T cells. Picomolar levels of CCL2 that were previously shown to inhibit T-cell migration to lymph nodes suppressed CD151 expression and dissociated CD151-integrin complexes in T lymphocytes, resulting in attenuated migration toward T-cell attractant chemokines. To directly inhibit CD151 function, a truncated CD151 peptide fragment mimicking of the CD151 extracellular loop was designed. CD151 extracellular loop inhibited T-cell migration in vitro and in vivo and attenuated the development of dextrane sulfate sodium-induced colitis. Thus, CD151 is a key orchestrator of T cell motility; interference with its proper function results in attenuated progression of inflammatory bowel disease.
Assuntos
Movimento Celular/imunologia , Colite Ulcerativa/imunologia , Doença de Crohn/imunologia , Inflamação/imunologia , Linfócitos T/imunologia , Tetraspanina 24/fisiologia , Animais , Estudos de Casos e Controles , Movimento Celular/fisiologia , Seguimentos , Proteínas de Homeodomínio/fisiologia , Humanos , Antígenos Comuns de Leucócito/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Prognóstico , Receptores CCR2/fisiologiaRESUMO
Wiskott-Aldrich syndrome (WAS) is an X-linked immunodeficiency disorder frequently associated with systemic autoimmunity, including autoantibody-mediated cytopenias. WAS protein (WASp)-deficient B cells have increased B cell receptor (BCR) and Toll-like receptor (TLR) signaling, suggesting that these pathways might impact establishment of the mature, naive BCR repertoire. To directly investigate this possibility, we evaluated naive B cell specificity and composition in WASp-deficient mice and WAS subjects (n = 12). High-throughput sequencing and single-cell cloning analysis of the BCR repertoire revealed altered heavy chain usage and enrichment for low-affinity self-reactive specificities in murine marginal zone and human naive B cells. Although negative selection mechanisms including deletion, anergy, and receptor editing were relatively unperturbed, WASp-deficient transitional B cells showed enhanced proliferation in vivo mediated by antigen- and Myd88-dependent signals. Finally, using both BCR sequencing and cell surface analysis with a monoclonal antibody recognizing an intrinsically autoreactive heavy chain, we show enrichment in self-reactive cells specifically at the transitional to naive mature B cell stage in WAS subjects. Our combined data support a model wherein modest alterations in B cell-intrinsic, BCR, and TLR signals in WAS, and likely other autoimmune disorders, are sufficient to alter B cell tolerance via positive selection of self-reactive transitional B cells.