RESUMO
SGK1 is an AGC kinase that regulates the expression of membrane sodium channels in renal tubular cells in a manner dependent on the metabolic checkpoint kinase complex mTORC2. We hypothesized that SGK1 might represent an additional mTORC2-dependent regulator of the differentiation and function of T cells. Here we found that after activation by mTORC2, SGK1 promoted T helper type 2 (TH2) differentiation by negatively regulating degradation of the transcription factor JunB mediated by the E3 ligase Nedd4-2. Simultaneously, SGK1 repressed the production of interferon-γ (IFN-γ) by controlling expression of the long isoform of the transcription factor TCF-1. Consistent with those findings, mice with selective deletion of SGK1 in T cells were resistant to experimentally induced asthma, generated substantial IFN-γ in response to viral infection and more readily rejected tumors.
Assuntos
Asma/imunologia , Proteínas Imediatamente Precoces/metabolismo , Melanoma Experimental/imunologia , Complexos Multiproteicos/imunologia , Infecções por Poxviridae/imunologia , Proteínas Serina-Treonina Quinases/metabolismo , Serina-Treonina Quinases TOR/imunologia , Células Th1/imunologia , Células Th2/imunologia , Vaccinia virus/imunologia , Imunidade Adaptativa/genética , Animais , Diferenciação Celular/genética , Células Cultivadas , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Regulação da Expressão Gênica/genética , Fator 1-alfa Nuclear de Hepatócito , Proteínas Imediatamente Precoces/genética , Interferon gama/genética , Interferon gama/metabolismo , Alvo Mecanístico do Complexo 2 de Rapamicina , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ubiquitina-Proteína Ligases Nedd4 , Proteínas Serina-Treonina Quinases/genética , Fator 1 de Transcrição de Linfócitos T/genética , Fator 1 de Transcrição de Linfócitos T/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Carga Tumoral/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
The chromatin organizer SATB1 is highly enriched in thymocytes and is essential for T-cell development. Although SATB1 regulates a large number of genes important for T-cell development, the mechanism(s) regulating expression of SATB1 during this process remain elusive. Using chromatin immune precipitation-seq-based occupancy profiles of H3K4me3 and H3Kme1 at Satb1 gene locus, we predicted four different alternative promoters of Satb1 in mouse thymocytes and characterized them. The expression of Satb1 transcript variants with distinct 5' UTRs occurs in a stage-specific manner during T-cell development and is dependent on TCR signaling. The observed discrepancy between the expression levels of SATB1 mRNA and protein in developing thymocytes can be explained by the differential translatability of Satb1 transcript variants as confirmed by polysome profiling and in vitro translation assay. We show that Satb1 alternative promoters exhibit lineage-specific chromatin accessibility during T-cell development from progenitors. Furthermore, TCF1 regulates the Satb1 P2 promoter switch during CD4SP development, via direct binding to the Satb1 P2 promoter. CD4SP T cells from TCF1 KO mice exhibit downregulation of P2 transcript variant expression as well as low levels of SATB1 protein. Collectively, these results provide unequivocal evidence toward alternative promoter switch-mediated developmental stage-specific regulation of SATB1 in thymocytes.
Assuntos
Cromatina/metabolismo , Proteínas de Ligação à Região de Interação com a Matriz/genética , Regiões Promotoras Genéticas , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/citologia , Linfócitos T/metabolismo , Animais , Linfócitos T CD4-Positivos/metabolismo , Diferenciação Celular , Linhagem da Célula , Cromatina/genética , Fator 1-alfa Nuclear de Hepatócito/metabolismo , Proteínas de Ligação à Região de Interação com a Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Biossíntese de Proteínas , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Transdução de Sinais , Timócitos/citologia , Timócitos/metabolismoRESUMO
Neuritic plaques, a pathological hallmark in Alzheimer's disease (AD) brains, comprise extracellular aggregates of amyloid-beta (Aß) peptide and degenerating neurites that accumulate autolysosomes. We found that, in the brains of patients with AD and in AD mouse models, Aß plaque-associated Olig2- and NG2-expressing oligodendrocyte progenitor cells (OPCs), but not astrocytes, microglia, or oligodendrocytes, exhibit a senescence-like phenotype characterized by the upregulation of p21/CDKN1A, p16/INK4/CDKN2A proteins, and senescence-associated ß-galactosidase activity. Molecular interrogation of the Aß plaque environment revealed elevated levels of transcripts encoding proteins involved in OPC function, replicative senescence, and inflammation. Direct exposure of cultured OPCs to aggregating Aß triggered cell senescence. Senolytic treatment of AD mice selectively removed senescent cells from the plaque environment, reduced neuroinflammation, lessened Aß load, and ameliorated cognitive deficits. Our findings suggest a role for Aß-induced OPC cell senescence in neuroinflammation and cognitive deficits in AD, and a potential therapeutic benefit of senolytic treatments.
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/psicologia , Peptídeos beta-Amiloides/metabolismo , Senescência Celular , Dasatinibe/administração & dosagem , Células Precursoras de Oligodendrócitos/metabolismo , Quercetina/administração & dosagem , Doença de Alzheimer/tratamento farmacológico , Peptídeos beta-Amiloides/administração & dosagem , Animais , Senescência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Feminino , Masculino , Aprendizagem em Labirinto/efeitos dos fármacos , Camundongos Transgênicos , Placa Amiloide/ultraestrutura , Prosencéfalo/metabolismo , Prosencéfalo/ultraestruturaRESUMO
T lymphocyte development and differentiation is a multi-step process that begins in the thymus and completed in the periphery. Sequential development of thymocytes is dependent on T cell receptor (TCR) signaling and an array of transcription factors. In this study we show that special AT-rich binding protein 1 (SATB1), a T lineage-enriched chromatin organizer and regulator, is induced in response to TCR signaling during early thymocyte development. SATB1 expression profile coincides with T lineage commitment and upregulation of SATB1 correlates with positive selection of thymocytes. CD4 thymocytes exhibit a characteristic bimodal expression pattern that corresponds to immature and mature CD4 thymocytes. We also demonstrate that GATA3, the key transcriptional regulator of αß T cells positively regulates SATB1 expression in thymocytes suggesting an important role for SATB1 during T cell development.