RESUMO
Diversity in the genetic lesions that cause cancer is extreme. In consequence, a pressing challenge is the development of drugs that target patient-specific disease mechanisms. To address this challenge, we employed a chemistry-first discovery paradigm for de novo identification of druggable targets linked to robust patient selection hypotheses. In particular, a 200,000 compound diversity-oriented chemical library was profiled across a heavily annotated test-bed of >100 cellular models representative of the diverse and characteristic somatic lesions for lung cancer. This approach led to the delineation of 171 chemical-genetic associations, shedding light on the targetability of mechanistic vulnerabilities corresponding to a range of oncogenotypes present in patient populations lacking effective therapy. Chemically addressable addictions to ciliogenesis in TTC21B mutants and GLUT8-dependent serine biosynthesis in KRAS/KEAP1 double mutants are prominent examples. These observations indicate a wealth of actionable opportunities within the complex molecular etiology of cancer.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/patologia , Proliferação de Células/efeitos dos fármacos , Neoplasias Pulmonares/patologia , Bibliotecas de Moléculas Pequenas/farmacologia , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Linhagem Celular Tumoral , Família 4 do Citocromo P450/deficiência , Família 4 do Citocromo P450/genética , Descoberta de Drogas , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Glucocorticoides/farmacologia , Proteínas Facilitadoras de Transporte de Glucose/antagonistas & inibidores , Proteínas Facilitadoras de Transporte de Glucose/genética , Proteínas Facilitadoras de Transporte de Glucose/metabolismo , Humanos , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Neoplasias Pulmonares/metabolismo , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Mutação , Fator 2 Relacionado a NF-E2/antagonistas & inibidores , Fator 2 Relacionado a NF-E2/genética , Fator 2 Relacionado a NF-E2/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Receptor Notch2/genética , Receptor Notch2/metabolismo , Receptores de Glucocorticoides/antagonistas & inibidores , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/metabolismoRESUMO
The normal stress response in humans is governed by the hypothalamic-pituitary-adrenal (HPA) axis through heightened mechanisms during stress, raising blood levels of the glucocorticoid hormone cortisol. Glucocorticoids are quintessential compounds that balance the proper functioning of numerous systems in the mammalian body. They are also generated synthetically and are the preeminent therapy for inflammatory diseases. They act by binding to the nuclear receptor transcription factor glucocorticoid receptor (GR), which has two main isoforms (GRα and GRß). Our classical understanding of glucocorticoid signaling is from the GRα isoform, which binds the hormone, whereas GRß has no known ligands. With glucocorticoids being involved in many physiological and cellular processes, even small disruptions in their release via the HPA axis, or changes in GR isoform expression, can have dire ramifications on health. Long-term chronic glucocorticoid therapy can lead to a glucocorticoid-resistant state, and we deliberate how this impacts disease treatment. Chronic glucocorticoid treatment can lead to noticeable side effects such as weight gain, adiposity, diabetes, and others that we discuss in detail. There are sexually dimorphic responses to glucocorticoids, and women tend to have a more hyperresponsive HPA axis than men. This review summarizes our understanding of glucocorticoids and critically analyzes the GR isoforms and their beneficial and deleterious mechanisms and the sexual differences that cause a dichotomy in responses. We also discuss the future of glucocorticoid therapy and propose a new concept of dual GR isoform agonist and postulate why activating both isoforms may prevent glucocorticoid resistance.
Assuntos
Glucocorticoides , Sistema Hipotálamo-Hipofisário , Masculino , Animais , Feminino , Humanos , Glucocorticoides/metabolismo , Sistema Hipotálamo-Hipofisário/metabolismo , Caracteres Sexuais , Sistema Hipófise-Suprarrenal/metabolismo , Receptores de Glucocorticoides/metabolismo , Isoformas de Proteínas/metabolismo , Mamíferos/metabolismoRESUMO
The glucocorticoid receptor (GR) binds the human genome at >10,000 sites but only regulates the expression of hundreds of genes. To determine the functional effect of each site, we measured the glucocorticoid (GC) responsive activity of nearly all GR binding sites (GBSs) captured using chromatin immunoprecipitation (ChIP) in A549 cells. 13% of GBSs assayed had GC-induced activity. The responsive sites were defined by direct GR binding via a GC response element (GRE) and exclusively increased reporter-gene expression. Meanwhile, most GBSs lacked GC-induced reporter activity. The non-responsive sites had epigenetic features of steady-state enhancers and clustered around direct GBSs. Together, our data support a model in which clusters of GBSs observed with ChIP-seq reflect interactions between direct and tethered GBSs over tens of kilobases. We further show that those interactions can synergistically modulate the activity of direct GBSs and may therefore play a major role in driving gene activation in response to GCs.
Assuntos
Genoma Humano , Glucocorticoides/metabolismo , Receptores de Glucocorticoides/metabolismo , Fatores de Transcrição/metabolismo , Ativação Transcricional , Células A549 , Sítios de Ligação/efeitos dos fármacos , Imunoprecipitação da Cromatina , Dexametasona/metabolismo , Dexametasona/farmacologia , Genes Reporter , Glucocorticoides/farmacologia , Humanos , Ligação Proteica/efeitos dos fármacos , Elementos de RespostaRESUMO
Controlling the balance between immunity and immunopathology is crucial for host resistance to pathogens. After infection, activation of the hypothalamic-pituitary-adrenal (HPA) axis leads to the production of glucocorticoids. However, the pleiotropic effects of these steroid hormones make it difficult to delineate their precise role(s) in vivo. Here we found that the regulation of natural killer (NK) cell function by the glucocorticoid receptor (GR) was required for host survival after infection with mouse cytomegalovirus (MCMV). Mechanistically, endogenous glucocorticoids produced shortly after infection induced selective and tissue-specific expression of the checkpoint receptor PD-1 on NK cells. This glucocorticoid-PD-1 pathway limited production of the cytokine IFN-γ by spleen NK cells, which prevented immunopathology. Notably, this regulation did not compromise viral clearance. Thus, the fine tuning of NK cell functions by the HPA axis preserved tissue integrity without impairing pathogen elimination, which reveals a novel aspect of neuroimmune regulation.
Assuntos
Glucocorticoides/metabolismo , Infecções por Herpesviridae/imunologia , Células Matadoras Naturais/fisiologia , Muromegalovirus/fisiologia , Receptor de Morte Celular Programada 1/metabolismo , Receptores de Glucocorticoides/metabolismo , Animais , Células Cultivadas , Feminino , Sistema Hipotálamo-Hipofisário , Imunidade Inata , Interferon gama/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neuroimunomodulação , Especificidade de Órgãos , Sistema Hipófise-Suprarrenal , Receptores de Glucocorticoides/genética , Transdução de Sinais , Carga ViralRESUMO
Glucocorticoids represent the mainstay of therapy for a broad spectrum of immune-mediated inflammatory diseases. However, the molecular mechanisms underlying their anti-inflammatory mode of action have remained incompletely understood1. Here we show that the anti-inflammatory properties of glucocorticoids involve reprogramming of the mitochondrial metabolism of macrophages, resulting in increased and sustained production of the anti-inflammatory metabolite itaconate and consequent inhibition of the inflammatory response. The glucocorticoid receptor interacts with parts of the pyruvate dehydrogenase complex whereby glucocorticoids provoke an increase in activity and enable an accelerated and paradoxical flux of the tricarboxylic acid (TCA) cycle in otherwise pro-inflammatory macrophages. This glucocorticoid-mediated rewiring of mitochondrial metabolism potentiates TCA-cycle-dependent production of itaconate throughout the inflammatory response, thereby interfering with the production of pro-inflammatory cytokines. By contrast, artificial blocking of the TCA cycle or genetic deficiency in aconitate decarboxylase 1, the rate-limiting enzyme of itaconate synthesis, interferes with the anti-inflammatory effects of glucocorticoids and, accordingly, abrogates their beneficial effects during a diverse range of preclinical models of immune-mediated inflammatory diseases. Our findings provide important insights into the anti-inflammatory properties of glucocorticoids and have substantial implications for the design of new classes of anti-inflammatory drugs.
Assuntos
Anti-Inflamatórios , Glucocorticoides , Inflamação , Macrófagos , Mitocôndrias , Succinatos , Animais , Feminino , Humanos , Masculino , Camundongos , Anti-Inflamatórios/farmacologia , Carboxiliases/metabolismo , Carboxiliases/antagonistas & inibidores , Ciclo do Ácido Cítrico/efeitos dos fármacos , Ciclo do Ácido Cítrico/genética , Citocinas/imunologia , Citocinas/metabolismo , Glucocorticoides/farmacologia , Glucocorticoides/metabolismo , Hidroliases/deficiência , Hidroliases/genética , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Mitocôndrias/efeitos dos fármacos , Complexo Piruvato Desidrogenase/metabolismo , Receptores de Glucocorticoides/metabolismo , Succinatos/metabolismo , Ativação Enzimática/efeitos dos fármacosRESUMO
Folding of stringent clients requires transfer from Hsp70 to Hsp90. The co-chaperone Hop physically connects the chaperone machineries. Here, we define its role from the remodeling of Hsp70/40-client complexes to the mechanism of client transfer and the conformational switching from stalled to active client-processing states of Hsp90. We show that Hsp70 together with Hsp40 completely unfold a stringent client, the glucocorticoid receptor ligand-binding domain (GR-LBD) in large assemblies. Hop remodels these for efficient transfer onto Hsp90. As p23 enters, Hsp70 leaves the complex via switching between binding sites in Hop. Current concepts assume that to proceed to client folding, Hop dissociates and the co-chaperone p23 stabilizes the Hsp90 closed state. In contrast, we show that p23 functionally interacts with Hop, relieves the stalling Hsp90-Hop interaction, and closes Hsp90. This reaction allows folding of the client and is thus the key regulatory step for the progression of the chaperone cycle.
Assuntos
Dobramento de Proteína , Piridinolcarbamato , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Humanos , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Ligação Proteica , Receptores de Glucocorticoides/metabolismoRESUMO
In the eukaryotic cytosol, the Hsp70 and the Hsp90 chaperone machines work in tandem with the maturation of a diverse array of client proteins. The transfer of nonnative clients between these systems is essential to the chaperoning process, but how it is regulated is still not clear. We discovered that NudC is an essential transfer factor with an unprecedented mode of action: NudC interacts with Hsp40 in Hsp40-Hsp70-client complexes and displaces Hsp70. Then, the interaction of NudC with Hsp90 allows the direct transfer of Hsp40-bound clients to Hsp90 for further processing. Consistent with this mechanism, NudC increases client activation in vitro as well as in cells and is essential for cellular viability. Together, our results show the complexity of the cooperation between the major chaperone machineries in the eukaryotic cytosol.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Proteínas Nucleares/metabolismo , Sítios de Ligação , Proteínas de Ciclo Celular/genética , Sobrevivência Celular , Células HEK293 , Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP90/genética , Humanos , Células K562 , Cinética , Simulação de Acoplamento Molecular , Proteínas Nucleares/genética , Ligação Proteica , Dobramento de Proteína , Domínios e Motivos de Interação entre Proteínas , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
The hormone-stimulated glucocorticoid receptor (GR) modulates transcription by interacting with thousands of enhancers and GR binding sites (GBSs) throughout the genome. Here, we examined the effects of GR binding on enhancer dynamics and investigated the contributions of individual GBSs to the hormone response. Hormone treatment resulted in genome-wide reorganization of the enhancer landscape in breast cancer cells. Upstream of the DDIT4 oncogene, GR bound to four sites constituting a hormone-dependent super enhancer. Three GBSs were required as hormone-dependent enhancers that differentially promoted histone acetylation, transcription frequency, and burst size. Conversely, the fourth site suppressed transcription and hormone treatment alleviated this suppression. GR binding within the super enhancer promoted a loop-switching mechanism that allowed interaction of the DDIT4 TSS with the active GBSs. The unique functions of each GR binding site contribute to hormone-induced transcriptional heterogeneity and demonstrate the potential for targeted modulation of oncogene expression.
Assuntos
Antineoplásicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Dexametasona/farmacologia , Elementos Facilitadores Genéticos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Receptores de Glucocorticoides/agonistas , Fatores de Transcrição/metabolismo , Transcrição Gênica/efeitos dos fármacos , Sítios de Ligação , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Feminino , Humanos , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Transdução de Sinais , Fatores de Transcrição/genéticaRESUMO
Dynamic changes in the expression of transcription factors (TFs) can influence the specification of distinct CD8+ T cell fates, but the observation of equivalent expression of TFs among differentially fated precursor cells suggests additional underlying mechanisms. Here we profiled the genome-wide histone modifications, open chromatin and gene expression of naive, terminal-effector, memory-precursor and memory CD8+ T cell populations induced during the in vivo response to bacterial infection. Integration of these data suggested that the expression and binding of TFs contributed to the establishment of subset-specific enhancers during differentiation. We developed a new bioinformatics method using the PageRank algorithm to reveal key TFs that influence the generation of effector and memory populations. The TFs YY1 and Nr3c1, both constitutively expressed during CD8+ T cell differentiation, regulated the formation of terminal-effector cell fates and memory-precursor cell fates, respectively. Our data define the epigenetic landscape of differentiation intermediates and facilitate the identification of TFs with previously unappreciated roles in CD8+ T cell differentiation.
Assuntos
Linfócitos T CD8-Positivos/fisiologia , Epigênese Genética , Listeriose/imunologia , Receptores de Glucocorticoides/metabolismo , Subpopulações de Linfócitos T/fisiologia , Fator de Transcrição YY1/metabolismo , Animais , Linfócitos T CD8-Positivos/microbiologia , Diferenciação Celular/genética , Biologia Computacional , Elementos Facilitadores Genéticos/genética , Perfilação da Expressão Gênica , Histonas/metabolismo , Memória Imunológica/genética , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Glucocorticoides/genética , Subpopulações de Linfócitos T/microbiologia , Fator de Transcrição YY1/genéticaRESUMO
Identifying signals in the tumor microenvironment (TME) that shape CD8+ T cell phenotype can inform novel therapeutic approaches for cancer. Here, we identified a gradient of increasing glucocorticoid receptor (GR) expression and signaling from naïve to dysfunctional CD8+ tumor-infiltrating lymphocytes (TILs). Conditional deletion of the GR in CD8+ TILs improved effector differentiation, reduced expression of the transcription factor TCF-1, and inhibited the dysfunctional phenotype, culminating in tumor growth inhibition. GR signaling transactivated the expression of multiple checkpoint receptors and promoted the induction of dysfunction-associated genes upon T cell activation. In the TME, monocyte-macrophage lineage cells produced glucocorticoids and genetic ablation of steroidogenesis in these cells as well as localized pharmacologic inhibition of glucocorticoid biosynthesis improved tumor growth control. Active glucocorticoid signaling associated with failure to respond to checkpoint blockade in both preclinical models and melanoma patients. Thus, endogenous steroid hormone signaling in CD8+ TILs promotes dysfunction, with important implications for cancer immunotherapy.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Glucocorticoides/metabolismo , Macrófagos/metabolismo , Melanoma Experimental/patologia , Microambiente Tumoral/imunologia , Animais , Linfócitos T CD8-Positivos/citologia , Linhagem Celular Tumoral , Hematopoese/imunologia , Fator 1-alfa Nuclear de Hepatócito/biossíntese , Inibidores de Checkpoint Imunológico , Ativação Linfocitária/imunologia , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Transdução de Sinais/imunologiaRESUMO
The glucocorticoid receptor (GR) is a constitutively expressed transcriptional regulatory factor (TRF) that controls many distinct gene networks, each uniquely determined by particular cellular and physiological contexts. The precision of GR-mediated responses seems to depend on combinatorial, context-specific assembly of GR-nucleated transcription regulatory complexes at genomic response elements. In turn, evidence suggests that context-driven plasticity is conferred by the integration of multiple signals, each serving as an allosteric effector of GR conformation, a key determinant of regulatory complex composition and activity. This structural and mechanistic perspective on GR regulatory specificity is likely to extend to other eukaryotic TRFs.
Assuntos
Receptores de Glucocorticoides/química , Receptores de Glucocorticoides/metabolismo , Acetilação , Animais , Montagem e Desmontagem da Cromatina , DNA/metabolismo , Regulação da Expressão Gênica , Humanos , Fosforilação , Domínios Proteicos , Receptores de Glucocorticoides/genética , Elementos de Resposta , Sumoilação , Transcrição GênicaRESUMO
The glucocorticoid receptor (GR), like many signaling proteins, depends on the Hsp90 molecular chaperone for in vivo function. Although Hsp90 is required for ligand binding in vivo, purified apo GR is capable of binding ligand with no enhancement from Hsp90. We reveal that Hsp70, known to facilitate client delivery to Hsp90, inactivates GR through partial unfolding, whereas Hsp90 reverses this inactivation. Full recovery of ligand binding requires ATP hydrolysis on Hsp90 and the Hop and p23 cochaperones. Surprisingly, Hsp90 ATP hydrolysis appears to regulate client transfer from Hsp70, likely through a coupling of the two chaperone's ATP cycles. Such coupling is embodied in contacts between Hsp90 and Hsp70 in the GR:Hsp70:Hsp90:Hop complex imaged by cryoelectron microscopy. Whereas GR released from Hsp70 is aggregation prone, release from Hsp90 protects GR from aggregation and enhances its ligand affinity. Together, this illustrates how coordinated chaperone interactions can enhance stability, function, and regulation.
Assuntos
Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Receptores de Glucocorticoides/química , Receptores de Glucocorticoides/metabolismo , Trifosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Dobramento de ProteínaRESUMO
Transcription factors (TFs) regulate gene expression by binding to specific consensus motifs within the local chromatin context. The mechanisms by which TFs navigate the nuclear environment as they search for binding sites remain unclear. Here, we used single-molecule tracking and machine-learning-based classification to directly measure the nuclear mobility of the glucocorticoid receptor (GR) in live cells. We revealed two distinct and dynamic low-mobility populations. One accounts for specific binding to chromatin, while the other represents a confinement state that requires an intrinsically disordered region (IDR), implicated in liquid-liquid condensate subdomains. Further analysis showed that the dwell times of both subpopulations follow a power-law distribution, consistent with a broad distribution of affinities on the GR cistrome and interactome. Together, our data link IDRs with a confinement state that is functionally distinct from specific chromatin binding and modulates the transcriptional output by increasing the local concentration of TFs at specific sites.
Assuntos
Proteínas Intrinsicamente Desordenadas/química , Receptores de Glucocorticoides/química , Fatores de Transcrição/química , Animais , Feminino , Proteínas Intrinsicamente Desordenadas/genética , Proteínas Intrinsicamente Desordenadas/metabolismo , Camundongos , Ratos , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
The glucocorticoid receptor (GR) is a major nuclear receptor (NR) drug target for the treatment of inflammatory disorders and several cancers. Despite the effectiveness of GR ligands, their systemic action triggers a plethora of side effects, limiting long-term use. Here, we discuss new concepts of and insights into GR mechanisms of action to assist in the identification of routes toward enhanced therapeutic benefits. We zoom in on the communication between different GR domains and how this is influenced by different ligands. We detail findings on the interaction between GR and chromatin, and highlight how condensate formation and coregulator confinement can perturb GR transcriptional responses. Last, we discuss the potential of novel ligands and the therapeutic exploitation of crosstalk with other NRs.
Assuntos
Receptores de Glucocorticoides , Transdução de Sinais , Receptores de Glucocorticoides/metabolismo , Humanos , Transdução de Sinais/efeitos dos fármacos , Animais , Cromatina/metabolismo , LigantesRESUMO
The treatment of advanced prostate cancer has been transformed by novel antiandrogen therapies such as enzalutamide. Here, we identify induction of glucocorticoid receptor (GR) expression as a common feature of drug-resistant tumors in a credentialed preclinical model, a finding also confirmed in patient samples. GR substituted for the androgen receptor (AR) to activate a similar but distinguishable set of target genes and was necessary for maintenance of the resistant phenotype. The GR agonist dexamethasone was sufficient to confer enzalutamide resistance, whereas a GR antagonist restored sensitivity. Acute AR inhibition resulted in GR upregulation in a subset of prostate cancer cells due to relief of AR-mediated feedback repression of GR expression. These findings establish a mechanism of escape from AR blockade through expansion of cells primed to drive AR target genes via an alternative nuclear receptor upon drug exposure.
Assuntos
Antagonistas de Androgênios/uso terapêutico , Antagonistas de Receptores de Andrógenos/uso terapêutico , Resistencia a Medicamentos Antineoplásicos , Feniltioidantoína/análogos & derivados , Neoplasias da Próstata/tratamento farmacológico , Receptores de Glucocorticoides/metabolismo , Animais , Benzamidas , Modelos Animais de Doenças , Regulação da Expressão Gênica , Xenoenxertos , Humanos , Masculino , Camundongos , Transplante de Neoplasias , Nitrilas , Feniltioidantoína/uso terapêutico , Receptores Androgênicos/metabolismo , TranscriptomaRESUMO
Maintaining a healthy proteome is fundamental for the survival of all organisms1. Integral to this are Hsp90 and Hsp70, molecular chaperones that together facilitate the folding, remodelling and maturation of the many 'client proteins' of Hsp902. The glucocorticoid receptor (GR) is a model client protein that is strictly dependent on Hsp90 and Hsp70 for activity3-7. Chaperoning GR involves a cycle of inactivation by Hsp70; formation of an inactive GR-Hsp90-Hsp70-Hop 'loading' complex; conversion to an active GR-Hsp90-p23 'maturation' complex; and subsequent GR release8. However, to our knowledge, a molecular understanding of this intricate chaperone cycle is lacking for any client protein. Here we report the cryo-electron microscopy structure of the GR-loading complex, in which Hsp70 loads GR onto Hsp90, uncovering the molecular basis of direct coordination by Hsp90 and Hsp70. The structure reveals two Hsp70 proteins, one of which delivers GR and the other scaffolds the Hop cochaperone. Hop interacts with all components of the complex, including GR, and poises Hsp90 for subsequent ATP hydrolysis. GR is partially unfolded and recognized through an extended binding pocket composed of Hsp90, Hsp70 and Hop, revealing the mechanism of GR loading and inactivation. Together with the GR-maturation complex structure9, we present a complete molecular mechanism of chaperone-dependent client remodelling, and establish general principles of client recognition, inhibition, transfer and activation.
Assuntos
Proteínas de Choque Térmico HSP70 , Proteínas de Choque Térmico HSP90 , Proteínas de Homeodomínio , Dobramento de Proteína , Receptores de Glucocorticoides , Microscopia Crioeletrônica , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Proteínas de Homeodomínio/metabolismo , Humanos , Chaperonas Moleculares/metabolismo , Ligação Proteica , Receptores de Glucocorticoides/metabolismoRESUMO
Diffuse large B cell lymphoma (DLBCL) is the most common B cell non-Hodgkin lymphoma and remains incurable in around 40% of patients. Efforts to sequence the coding genome identified several genes and pathways that are altered in this disease, including potential therapeutic targets1-5. However, the non-coding genome of DLBCL remains largely unexplored. Here we show that active super-enhancers are highly and specifically hypermutated in 92% of samples from individuals with DLBCL, display signatures of activation-induced cytidine deaminase activity, and are linked to genes that encode B cell developmental regulators and oncogenes. As evidence of oncogenic relevance, we show that the hypermutated super-enhancers linked to the BCL6, BCL2 and CXCR4 proto-oncogenes prevent the binding and transcriptional downregulation of the corresponding target gene by transcriptional repressors, including BLIMP1 (targeting BCL6) and the steroid receptor NR3C1 (targeting BCL2 and CXCR4). Genetic correction of selected mutations restored repressor DNA binding, downregulated target gene expression and led to the counter-selection of cells containing corrected alleles, indicating an oncogenic dependency on the super-enhancer mutations. This pervasive super-enhancer mutational mechanism reveals a major set of genetic lesions deregulating gene expression, which expands the involvement of known oncogenes in DLBCL pathogenesis and identifies new deregulated gene targets of therapeutic relevance.
Assuntos
Elementos Facilitadores Genéticos , Regulação Neoplásica da Expressão Gênica , Linfoma Difuso de Grandes Células B , Mutação , Oncogenes , Regulação para Baixo , Elementos Facilitadores Genéticos/genética , Humanos , Linfoma Difuso de Grandes Células B/genética , Linfoma Difuso de Grandes Células B/metabolismo , Oncogenes/genética , Fator 1 de Ligação ao Domínio I Regulador Positivo/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-6/genética , Receptores CXCR4/genética , Receptores de Glucocorticoides/metabolismo , Proteínas Repressoras/metabolismoRESUMO
Hsp90 is a conserved and essential molecular chaperone responsible for the folding and activation of hundreds of 'client' proteins1-3. The glucocorticoid receptor (GR) is a model client that constantly depends on Hsp90 for activity4-9. GR ligand binding was previously shown to nr inhibited by Hsp70 and restored by Hsp90, aided by the co-chaperone p2310. However, a molecular understanding of the chaperone-mediated remodelling that occurs between the inactive Hsp70-Hsp90 'client-loading complex' and an activated Hsp90-p23 'client-maturation complex' is lacking for any client, including GR. Here we present a cryo-electron microscopy (cryo-EM) structure of the human GR-maturation complex (GR-Hsp90-p23), revealing that the GR ligand-binding domain is restored to a folded, ligand-bound conformation, while being simultaneously threaded through the Hsp90 lumen. In addition, p23 directly stabilizes native GR using a C-terminal helix, resulting in enhanced ligand binding. This structure of a client bound to Hsp90 in a native conformation contrasts sharply with the unfolded kinase-Hsp90 structure11. Thus, aided by direct co-chaperone-client interactions, Hsp90 can directly dictate client-specific folding outcomes. Together with the GR-loading complex structure12, we present the molecular mechanism of chaperone-mediated GR remodelling, establishing the first, to our knowledge, complete chaperone cycle for any Hsp90 client.
Assuntos
Microscopia Crioeletrônica , Proteínas de Choque Térmico HSP90 , Prostaglandina-E Sintases , Receptores de Glucocorticoides , Proteínas de Choque Térmico HSP70/química , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP70/ultraestrutura , Proteínas de Choque Térmico HSP90/química , Proteínas de Choque Térmico HSP90/metabolismo , Proteínas de Choque Térmico HSP90/ultraestrutura , Humanos , Ligantes , Chaperonas Moleculares/química , Chaperonas Moleculares/metabolismo , Chaperonas Moleculares/ultraestrutura , Prostaglandina-E Sintases/química , Prostaglandina-E Sintases/metabolismo , Prostaglandina-E Sintases/ultraestrutura , Ligação Proteica , Receptores de Glucocorticoides/química , Receptores de Glucocorticoides/metabolismo , Receptores de Glucocorticoides/ultraestruturaRESUMO
The PTEN tumor suppressor controls cell death and survival by regulating functions of various molecular targets. While the role of PTEN lipid-phosphatase activity on PtdIns(3,4,5)P3 and inhibition of PI3K pathway is well characterized, the biological relevance of PTEN protein-phosphatase activity remains undefined. Here, using knockin (KI) mice harboring cancer-associated and functionally relevant missense mutations, we show that although loss of PTEN lipid-phosphatase function cooperates with oncogenic PI3K to promote rapid mammary tumorigenesis, the additional loss of PTEN protein-phosphatase activity triggered an extensive cell death response evident in early and advanced mammary tumors. Omics and drug-targeting studies revealed that PI3Ks act to reduce glucocorticoid receptor (GR) levels, which are rescued by loss of PTEN protein-phosphatase activity to restrain cell survival. Thus, we find that the dual regulation of GR by PI3K and PTEN functions as a rheostat that can be exploited for the treatment of PTEN loss-driven cancers.
Assuntos
Neoplasias Mamárias Animais/metabolismo , Neoplasias Mamárias Animais/patologia , PTEN Fosfo-Hidrolase/metabolismo , Receptores de Glucocorticoides/metabolismo , Animais , Carcinogênese , Morte Celular , Linhagem Celular Tumoral , Proliferação de Células , Dexametasona/farmacologia , Feminino , Humanos , Isoenzimas/metabolismo , Camundongos , Modelos Biológicos , Mutação/genética , Organoides/patologia , PTEN Fosfo-Hidrolase/genética , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Estabilidade Proteica , Proteoma/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismoRESUMO
Social interactions among animals mediate essential behaviours, including mating, nurturing, and defence1,2. The gut microbiota contribute to social activity in mice3,4, but the gut-brain connections that regulate this complex behaviour and its underlying neural basis are unclear5,6. Here we show that the microbiome modulates neuronal activity in specific brain regions of male mice to regulate canonical stress responses and social behaviours. Social deviation in germ-free and antibiotic-treated mice is associated with elevated levels of the stress hormone corticosterone, which is primarily produced by activation of the hypothalamus-pituitary-adrenal (HPA) axis. Adrenalectomy, antagonism of glucocorticoid receptors, or pharmacological inhibition of corticosterone synthesis effectively corrects social deficits following microbiome depletion. Genetic ablation of glucocorticoid receptors in specific brain regions or chemogenetic inactivation of neurons in the paraventricular nucleus of the hypothalamus that produce corticotrophin-releasing hormone (CRH) reverse social impairments in antibiotic-treated mice. Conversely, specific activation of CRH-expressing neurons in the paraventricular nucleus induces social deficits in mice with a normal microbiome. Via microbiome profiling and in vivo selection, we identify a bacterial species, Enterococcus faecalis, that promotes social activity and reduces corticosterone levels in mice following social stress. These studies suggest that specific gut bacteria can restrain the activation of the HPA axis, and show that the microbiome can affect social behaviours through discrete neuronal circuits that mediate stress responses in the brain.