RESUMO
Mammalian cells must integrate environmental cues to determine coherent physiological responses. The transcription factors Myc and YAP-TEAD act downstream from mitogenic signals, with the latter responding also to mechanical cues. Here, we show that these factors coordinately regulate genes required for cell proliferation. Activation of Myc led to extensive association with its genomic targets, most of which were prebound by TEAD. At these loci, recruitment of YAP was Myc-dependent and led to full transcriptional activation. This cooperation was critical for cell cycle entry, organ growth, and tumorigenesis. Thus, Myc and YAP-TEAD integrate mitogenic and mechanical cues at the transcriptional level to provide multifactorial control of cell proliferation.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proliferação de Células/genética , Fosfoproteínas/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Ativação Transcricional , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Ciclo Celular/genética , Proteínas de Ciclo Celular , Células Cultivadas , Peptídeos e Proteínas de Sinalização Intercelular/fisiologia , Mecanotransdução Celular , Camundongos , Camundongos Transgênicos , Fosfoproteínas/genética , Transdução de Sinais , Fatores de Transcrição/metabolismo , Proteínas de Sinalização YAPRESUMO
Differentiation of naïve peripheral B cells into terminally differentiated plasma cells is characterized by epigenetic alterations, yet the epigenetic mechanisms that control B-cell fate remain unclear. Here, we identified a role for the histone H3K79 methyltransferase DOT1L in controlling B-cell differentiation. Mouse B cells lacking Dot1L failed to establish germinal centers (GC) and normal humoral immune responses in vivo. In vitro, activated B cells in which Dot1L was deleted showed aberrant differentiation and prematurely acquired plasma cell characteristics. Similar results were obtained when DOT1L was chemically inhibited in mature B cells in vitro. Mechanistically, combined epigenomics and transcriptomics analysis revealed that DOT1L promotes expression of a pro-proliferative, pro-GC program. In addition, DOT1L indirectly supports the repression of an anti-proliferative plasma cell differentiation program by maintaining the repression of Polycomb Repressor Complex 2 (PRC2) targets. Our findings show that DOT1L is a key modulator of the core transcriptional and epigenetic landscape in B cells, establishing an epigenetic barrier that warrants B-cell naivety and GC B-cell differentiation.
Assuntos
Linfócitos B/citologia , Diferenciação Celular , Histona-Lisina N-Metiltransferase , Histonas , Metiltransferases , Animais , Epigênese Genética , Histona-Lisina N-Metiltransferase/genética , Histonas/genética , Histonas/metabolismo , Metiltransferases/genética , Metiltransferases/metabolismo , CamundongosRESUMO
Jmjd3, a JmjC family histone demethylase, is induced by the transcription factor NF-kB in response to microbial stimuli. Jmjd3 erases H3K27me3, a histone mark associated with transcriptional repression and involved in lineage determination. However, the specific contribution of Jmjd3 induction and H3K27me3 demethylation to inflammatory gene expression remains unknown. Using chromatin immunoprecipitation-sequencing we found that Jmjd3 is preferentially recruited to transcription start sites characterized by high levels of H3K4me3, a marker of gene activity, and RNA polymerase II (Pol_II). Moreover, 70% of lipopolysaccharide (LPS)-inducible genes were found to be Jmjd3 targets. Although most Jmjd3 target genes were unaffected by its deletion, a few hundred genes, including inducible inflammatory genes, showed moderately impaired Pol_II recruitment and transcription. Importantly, most Jmjd3 target genes were not associated with detectable levels of H3K27me3, and transcriptional effects of Jmjd3 absence in the window of time analysed were uncoupled from measurable effects on this histone mark. These data show that Jmjd3 fine-tunes the transcriptional output of LPS-activated macrophages in an H3K27 demethylation-independent manner.
Assuntos
Regulação da Expressão Gênica , Histona Desmetilases com o Domínio Jumonji/metabolismo , Lipopolissacarídeos/imunologia , Ativação de Macrófagos , Macrófagos/imunologia , Animais , Células Cultivadas , Feminino , Técnicas de Inativação de Genes , Histona Desmetilases com o Domínio Jumonji/análise , Histona Desmetilases com o Domínio Jumonji/genética , Macrófagos/metabolismo , CamundongosRESUMO
TAZ (WWTR1) is a transcriptional co-activator regulated by Hippo signaling, mechano-transduction, and G-protein couple receptors. Once activated, TAZ and its paralogue, YAP1, regulate gene expression programs promoting cell proliferation, survival, and differentiation, thus controlling embryonic development, tissue regeneration, and aging. YAP and TAZ are also frequently activated in tumors, particularly in poorly differentiated and highly aggressive malignancies. Yet, mutations of YAP/TAZ or of their upstream regulators do not fully account for their activation in cancer, raising the possibility that other upstream regulatory pathways, still to be defined, are altered in tumors. In this work, we set out to identify novel regulators of TAZ by means of a siRNA-based screen. We identified 200 genes able to modulate the transcriptional activity of TAZ, with prominence for genes implicated in cell-cell contact, cytoskeletal tension, cell migration, WNT signaling, chromatin remodeling, and interleukins and NF-kappaB signaling. Among these genes we identified was BRCC3, a component of the BRCA1 complex that guards genome integrity and exerts tumor suppressive activity during cancer development. The loss of BRCC3 or BRCA1 leads to an increased level and activity of TAZ. Follow-up studies indicated that the cytoplasmic BRCA1 complex controls the ubiquitination and stability of TAZ. This may suggest that, in tumors, inactivating mutations of BRCA1 may unleash cell transformation by activating the TAZ oncogene.
Assuntos
Neoplasias , Transativadores , Humanos , Transativadores/genética , Transativadores/metabolismo , Proteínas de Sinalização YAP , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Via de Sinalização Wnt , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Enzimas Desubiquitinantes/metabolismoRESUMO
The major function of B lymphocytes is to sense antigens and to produce protective antibodies after activation. This function requires the expression of a B-cell antigen receptor (BCR), and evolutionary conserved mechanisms seem to exist that ensure that B cells without a BCR do not develop nor survive in the periphery. Here, we show that the loss of BCR expression on Burkitt lymphoma cells leads to decreased mitochondrial function and impaired metabolic flexibility. Strikingly, this phenotype does not result from the absence of a classical Syk-dependent BCR signal but rather from compromised ER expansion. We show that the reexpression of immunoglobulins (Ig) in the absence of the BCR signaling subunits Igα and Igß rescues the observed metabolic defects. We demonstrate that immunoglobulin expression is needed to maintain ER homeostasis not only in lymphoma cells but also in resting B cells. Our study provides evidence that the expression of BCR components, which is sensed in the ER and shapes mitochondrial function, represents a novel mechanism of metabolic control in B cells.
Assuntos
Linfócitos B/metabolismo , Linfoma de Burkitt/metabolismo , Retículo Endoplasmático/imunologia , Imunoglobulina M/metabolismo , Transdução de Sinais/genética , Animais , Linfoma de Burkitt/patologia , Linhagem Celular Tumoral , Técnicas de Inativação de Genes , Homeostase/genética , Homeostase/imunologia , Humanos , Imunoglobulina M/genética , Camundongos , Camundongos Transgênicos , Mitocôndrias/metabolismo , Fenótipo , Receptores de Antígenos de Linfócitos B/genética , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de Sinais/imunologia , Quinase Syk/deficiência , Quinase Syk/genética , Transdução GenéticaRESUMO
The establishment of protective humoral immunity is dependent on the ability of mature B cells to undergo antibody gene diversification while adjusting to the physiological stressors induced by activation with the antigen. Mature B cells diversify their antibody genes by class switch recombination (CSR) and somatic hypermutation (SHM), which are both dependent on efficient induction of activation-induced cytidine deaminase (AID). Here, we identified PDGFA-associated protein 1 (Pdap1) as an essential regulator of cellular homeostasis in mature B cells. Pdap1 deficiency leads to sustained expression of the integrated stress response (ISR) effector activating transcription factor 4 (Atf4) and induction of the ISR transcriptional program, increased cell death, and defective AID expression. As a consequence, loss of Pdap1 reduces germinal center B cell formation and impairs CSR and SHM. Thus, Pdap1 protects mature B cells against chronic ISR activation and ensures efficient antibody diversification by promoting their survival and optimal function.
Assuntos
Diversidade de Anticorpos , Linfócitos B/metabolismo , Genes de Imunoglobulinas/genética , Animais , Linfócitos B/imunologia , Proteína 9 Associada à CRISPR , Sistemas CRISPR-Cas , Morte Celular , Diferenciação Celular , Linhagem Celular , Feminino , Imunofluorescência , Edição de Genes , Regulação da Expressão Gênica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos TransgênicosAssuntos
Hematopoese/genética , Neoplasias/genética , Proteínas Nucleares/genética , Fatores de Transcrição/genética , Aciltransferases , Animais , Proteínas de Ciclo Celular , Diferenciação Celular/genética , Modelos Animais de Doenças , Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Células-Tronco Hematopoéticas/patologia , Xenoenxertos , Humanos , Camundongos , Camundongos Transgênicos , Neoplasias/sangue , Neoplasias/metabolismo , Neoplasias/patologia , Proteínas Nucleares/metabolismo , Transdução de Sinais , Fatores de Transcrição/metabolismo , Resultado do TratamentoRESUMO
Protection against deadly pathogens requires the production of high-affinity antibodies by B cells, which are generated in germinal centers (GCs). Alteration of the GC developmental program is common in many B cell malignancies. Identification of regulators of the GC response is crucial to develop targeted therapies for GC B cell dysfunctions, including lymphomas. The histone H3 lysine 27 methyltransferase enhancer of zeste homolog 2 (EZH2) is highly expressed in GC B cells and is often constitutively activated in GC-derived non-Hodgkin lymphomas (NHLs). The function of EZH2 in GC B cells remains largely unknown. Herein, we show that Ezh2 inactivation in mouse GC B cells caused profound impairment of GC responses, memory B cell formation, and humoral immunity. EZH2 protected GC B cells against activation-induced cytidine deaminase (AID) mutagenesis, facilitated cell cycle progression, and silenced plasma cell determinant and tumor suppressor B-lymphocyte-induced maturation protein 1 (BLIMP1). EZH2 inhibition in NHL cells induced BLIMP1, which impaired tumor growth. In conclusion, EZH2 sustains AID function and prevents terminal differentiation of GC B cells, which allows antibody diversification and affinity maturation. Dysregulation of the GC reaction by constitutively active EZH2 facilitates lymphomagenesis and identifies EZH2 as a possible therapeutic target in NHL and other GC-derived B cell diseases.
Assuntos
Linfócitos B/imunologia , Centro Germinativo/enzimologia , Linfoma não Hodgkin/etiologia , Complexo Repressor Polycomb 2/fisiologia , Animais , Apoptose , Linfócitos B/patologia , Ciclo Celular , Citidina Desaminase/deficiência , Citidina Desaminase/genética , Citidina Desaminase/fisiologia , Dano ao DNA , Proteína Potenciadora do Homólogo 2 de Zeste , Ativação Enzimática , Regulação Neoplásica da Expressão Gênica , Rearranjo Gênico de Cadeia Pesada de Linfócito B , Inativação Gênica , Centro Germinativo/imunologia , Centro Germinativo/patologia , Imunidade Humoral , Memória Imunológica , Linfoma não Hodgkin/enzimologia , Linfoma não Hodgkin/genética , Linfoma não Hodgkin/patologia , Linfopoese , Metilação , Camundongos , Camundongos Transgênicos , Complexo Repressor Polycomb 2/deficiência , Complexo Repressor Polycomb 2/genética , Fator 1 de Ligação ao Domínio I Regulador Positivo , Processamento de Proteína Pós-Traducional , Fatores de Transcrição/fisiologiaRESUMO
Testosterone affects behavior. Whether regular physical training does influence these effects is unknown. The assumption that testosterone induces muscular hypertrophy if combined with physical training has not been confirmed experimentally. The aim of this study was to evaluate whether activity and/or testosterone treatment affects depression-like behavior and to observe the effects of activity and testosterone on muscle fiber diameter. Forty-three male rats were divided into 4 groups: two groups (TST act and TST lazy) were treated with testosterone (5mg/kg) and two groups were used as control (CTRL act and CTRL lazy). Two of the groups (CTRL act and TST act) underwent 2weeks of exercise. The forced swim test was used as a test of depression-like behavior. Sex steroids were measured and the diameter of skeletal muscle fibers was evaluated. Testosterone was significantly higher in both testosterone-treated groups (p<0.001). Physically active groups had higher immobility times in the forced swim test than inactive groups. Groups CTRL act and TST lazy showed significantly larger diameter of muscle fibers in comparison to the TST act group. Our results suggest that physical activity induces depression-like behavior in rats. Controversial antagonistic effects of testosterone and physical activity on muscle fiber diameter were found.
Assuntos
Comportamento Animal/fisiologia , Depressão/psicologia , Condicionamento Físico Animal/psicologia , Análise de Variância , Animais , Comportamento Animal/efeitos dos fármacos , Tamanho Celular/efeitos dos fármacos , Estradiol/sangue , Masculino , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/fisiologia , Fibras Musculares Esqueléticas/ultraestrutura , Progesterona/sangue , Ratos , Ratos Wistar , Natação/psicologia , Testosterona/sangue , Testosterona/farmacologiaRESUMO
JMJD3 (KDM6B) antagonizes Polycomb silencing by demethylating lysine 27 on histone H3. The interplay of methyltransferases and demethylases at this residue is thought to underlie critical cell fate transitions, and the dynamics of H3K27me3 during neurogenesis posited for JMJD3 a critical role in the acquisition of neural fate. Despite evidence of its involvement in early neural commitment, however, its role in the emergence and maturation of the mammalian CNS remains unknown. Here, we inactivated Jmjd3 in the mouse and found that its loss causes perinatal lethality with the complete and selective disruption of the pre-Bötzinger complex (PBC), the pacemaker of the respiratory rhythm generator. Through genetic and electrophysiological approaches, we show that the enzymatic activity of JMJD3 is selectively required for the maintenance of the PBC and controls critical regulators of PBC activity, uncovering an unanticipated role of this enzyme in the late structuring and function of neuronal networks.
Assuntos
Histona Desmetilases com o Domínio Jumonji/metabolismo , Neurônios/metabolismo , Animais , Linhagem Celular , Embrião de Mamíferos/metabolismo , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Histonas/metabolismo , Histona Desmetilases com o Domínio Jumonji/deficiência , Histona Desmetilases com o Domínio Jumonji/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mortalidade Perinatal , Explosão Respiratória/fisiologia , Insuficiência Respiratória/patologia , Somatostatina/metabolismoRESUMO
BACKGROUND: Soy phytoestrogens are known to influence the hormonal status acting as partial estrogen agonists. Soy-derived food supplements are advised for hormone replacement therapy, prevention of atherosclerosis, age-related cognitive decline and even hormone-dependent cancer, although results from clinical studies are controversial. Whether increased soybean intake can affect the endocrine status and cognitive abilities is largely unknown. AIM: To observe the effects of 1 week of increased soybean intake on sex hormone levels and spatial cognitive abilities in women. SUBJECTS AND METHODS: 16 young healthy female volunteers were asked to eat 900 g of soybeans within 1 week. Salivary testosterone (T), free and total plasma T, salivary and plasma estradiol (E) were measured by radioimmunoassay before and after the study period. Mental rotation (MR) and spatial visualization (SV) psychological tests were done at the days of sampling. RESULTS: Soybean intake increased total plasma T levels (p < 0.02) while decreasing salivary T (p < 0.01) and not altering free plasma T levels. Salivary and plasma E levels were not changed. The results of MR and SV tests were improved after the study period. CONCLUSION: Short-time increased soybean intake alters the level of total plasma and salivary T and improves spatial cognition in women. Whether this effect is mediated by modulation of estrogen receptors, changes in sex hormone-binding globulin production or changes in activity of steroid-competent enzymes needs further study.