RESUMO
SARS-CoV-2 is the cause of a pandemic with growing global mortality. Using comprehensive identification of RNA-binding proteins by mass spectrometry (ChIRP-MS), we identified 309 host proteins that bind the SARS-CoV-2 RNA during active infection. Integration of this data with ChIRP-MS data from three other RNA viruses defined viral specificity of RNA-host protein interactions. Targeted CRISPR screens revealed that the majority of functional RNA-binding proteins protect the host from virus-induced cell death, and comparative CRISPR screens across seven RNA viruses revealed shared and SARS-specific antiviral factors. Finally, by combining the RNA-centric approach and functional CRISPR screens, we demonstrated a physical and functional connection between SARS-CoV-2 and mitochondria, highlighting this organelle as a general platform for antiviral activity. Altogether, these data provide a comprehensive catalog of functional SARS-CoV-2 RNA-host protein interactions, which may inform studies to understand the host-virus interface and nominate host pathways that could be targeted for therapeutic benefit.
Assuntos
Interações Hospedeiro-Patógeno , RNA Viral/genética , SARS-CoV-2/genética , Animais , COVID-19/virologia , Sistemas CRISPR-Cas/genética , Linhagem Celular Tumoral , Chlorocebus aethiops , Feminino , Genoma Viral , Humanos , Pulmão/virologia , Masculino , Espectrometria de Massas , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Proteoma/metabolismo , Proteínas de Ligação a RNA/metabolismo , SARS-CoV-2/ultraestrutura , Células VeroRESUMO
Understanding the functional consequences of single-nucleotide variants is critical to uncovering the genetic underpinnings of diseases, but technologies to characterize variants are limiting. Here, we leverage CRISPR-Cas9 cytosine base editors in pooled screens to scalably assay variants at endogenous loci in mammalian cells. We benchmark the performance of base editors in positive and negative selection screens, identifying known loss-of-function mutations in BRCA1 and BRCA2 with high precision. To demonstrate the utility of base editor screens to probe small molecule-protein interactions, we screen against BH3 mimetics and PARP inhibitors, identifying point mutations that confer drug sensitivity or resistance. We also create a library of single guide RNAs (sgRNAs) predicted to generate 52,034 ClinVar variants in 3,584 genes and conduct screens in the presence of cellular stressors, identifying loss-of-function variants in numerous DNA damage repair genes. We anticipate that this screening approach will be broadly useful to readily and scalably functionalize genetic variants.
Assuntos
Edição de Genes , Variação Genética , Sequenciamento de Nucleotídeos em Larga Escala , Alelos , Proteína BRCA1/genética , Proteína BRCA2/genética , Sequência de Bases , Domínio Catalítico , Linhagem Celular Tumoral , Humanos , Mutação com Perda de Função , Mutagênese/genética , Proteína de Sequência 1 de Leucemia de Células Mieloides/genética , Mutação Puntual/genética , Poli(ADP-Ribose) Polimerases/química , Poli(ADP-Ribose) Polimerases/genética , Reprodutibilidade dos Testes , Seleção Genética , Proteína bcl-X/genéticaRESUMO
Since the first reports of a novel severe acute respiratory syndrome (SARS)-like coronavirus in December 2019 in Wuhan, China, there has been intense interest in understanding how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in the human population. Recent debate has coalesced around two competing ideas: a "laboratory escape" scenario and zoonotic emergence. Here, we critically review the current scientific evidence that may help clarify the origin of SARS-CoV-2.
Assuntos
SARS-CoV-2/fisiologia , Animais , Evolução Biológica , COVID-19/virologia , Humanos , Laboratórios , SARS-CoV-2/genética , Zoonoses/virologiaRESUMO
Identification of host genes essential for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection may reveal novel therapeutic targets and inform our understanding of coronavirus disease 2019 (COVID-19) pathogenesis. Here we performed genome-wide CRISPR screens in Vero-E6 cells with SARS-CoV-2, Middle East respiratory syndrome CoV (MERS-CoV), bat CoV HKU5 expressing the SARS-CoV-1 spike, and vesicular stomatitis virus (VSV) expressing the SARS-CoV-2 spike. We identified known SARS-CoV-2 host factors, including the receptor ACE2 and protease Cathepsin L. We additionally discovered pro-viral genes and pathways, including HMGB1 and the SWI/SNF chromatin remodeling complex, that are SARS lineage and pan-coronavirus specific, respectively. We show that HMGB1 regulates ACE2 expression and is critical for entry of SARS-CoV-2, SARS-CoV-1, and NL63. We also show that small-molecule antagonists of identified gene products inhibited SARS-CoV-2 infection in monkey and human cells, demonstrating the conserved role of these genetic hits across species. This identifies potential therapeutic targets for SARS-CoV-2 and reveals SARS lineage-specific and pan-CoV host factors that regulate susceptibility to highly pathogenic CoVs.
Assuntos
Infecções por Coronavirus/genética , Estudo de Associação Genômica Ampla , Interações Hospedeiro-Patógeno , SARS-CoV-2/fisiologia , Enzima de Conversão de Angiotensina 2/metabolismo , Animais , COVID-19/imunologia , COVID-19/virologia , Linhagem Celular , Chlorocebus aethiops , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Coronavirus/classificação , Infecções por Coronavirus/tratamento farmacológico , Infecções por Coronavirus/imunologia , Técnicas de Inativação de Genes , Redes Reguladoras de Genes , Células HEK293 , Proteína HMGB1/genética , Proteína HMGB1/metabolismo , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Humanos , Células Vero , Internalização do VírusRESUMO
Multiple sclerosis (MS) is an autoimmune disease characterized by attack on oligodendrocytes within the central nervous system (CNS). Despite widespread use of immunomodulatory therapies, patients may still face progressive disability because of failure of myelin regeneration and loss of neurons, suggesting additional cellular pathologies. Here, we describe a general approach for identifying specific cell types in which a disease allele exerts a pathogenic effect. Applying this approach to MS risk loci, we pinpoint likely pathogenic cell types for 70%. In addition to T cell loci, we unexpectedly identified myeloid- and CNS-specific risk loci, including two sites that dysregulate transcriptional pause release in oligodendrocytes. Functional studies demonstrated inhibition of transcriptional elongation is a dominant pathway blocking oligodendrocyte maturation. Furthermore, pause release factors are frequently dysregulated in MS brain tissue. These data implicate cell-intrinsic aberrations outside of the immune system and suggest new avenues for therapeutic development. VIDEO ABSTRACT.
Assuntos
Comunicação Celular/genética , Doença/genética , Oligodendroglia/metabolismo , Animais , Encéfalo/metabolismo , Sistema Nervoso Central/metabolismo , Doenças Desmielinizantes/metabolismo , Doenças Desmielinizantes/patologia , Humanos , Esclerose Múltipla/genética , Esclerose Múltipla/metabolismo , Esclerose Múltipla/fisiopatologia , Bainha de Mielina/metabolismo , Neurônios/metabolismo , Oligodendroglia/fisiologia , Fatores de RiscoRESUMO
The proteasome mediates selective protein degradation and is dynamically regulated in response to proteotoxic challenges. SKN-1A/Nrf1, an endoplasmic reticulum (ER)-associated transcription factor that undergoes N-linked glycosylation, serves as a sensor of proteasome dysfunction and triggers compensatory upregulation of proteasome subunit genes. Here, we show that the PNG-1/NGLY1 peptide:N-glycanase edits the sequence of SKN-1A protein by converting particular N-glycosylated asparagine residues to aspartic acid. Genetically introducing aspartates at these N-glycosylation sites bypasses the requirement for PNG-1/NGLY1, showing that protein sequence editing rather than deglycosylation is key to SKN-1A function. This pathway is required to maintain sufficient proteasome expression and activity, and SKN-1A hyperactivation confers resistance to the proteotoxicity of human amyloid beta peptide. Deglycosylation-dependent protein sequence editing explains how ER-associated and cytosolic isoforms of SKN-1 perform distinct cytoprotective functions corresponding to those of mammalian Nrf1 and Nrf2. Thus, we uncover an unexpected mechanism by which N-linked glycosylation regulates protein function and proteostasis.
Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Ligação a DNA/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Fatores de Transcrição/metabolismo , Sequência de Aminoácidos , Animais , Asparagina/metabolismo , Bortezomib/farmacologia , Sistemas CRISPR-Cas/genética , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/genética , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Retículo Endoplasmático/metabolismo , Edição de Genes , Regulação da Expressão Gênica/efeitos dos fármacos , Estresse Oxidativo , Complexo de Endopeptidases do Proteassoma/genética , Subunidades Proteicas/química , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , Alinhamento de Sequência , Fatores de Transcrição/química , Fatores de Transcrição/genéticaRESUMO
Non-coding regions amplified beyond oncogene borders have largely been ignored. Using a computational approach, we find signatures of significant co-amplification of non-coding DNA beyond the boundaries of amplified oncogenes across five cancer types. In glioblastoma, EGFR is preferentially co-amplified with its two endogenous enhancer elements active in the cell type of origin. These regulatory elements, their contacts, and their contribution to cell fitness are preserved on high-level circular extrachromosomal DNA amplifications. Interrogating the locus with a CRISPR interference screening approach reveals a diversity of additional elements that impact cell fitness. The pattern of fitness dependencies mirrors the rearrangement of regulatory elements and accompanying rewiring of the chromatin topology on the extrachromosomal amplicon. Our studies indicate that oncogene amplifications are shaped by regulatory dependencies in the non-coding genome.
Assuntos
Cromossomos Humanos/genética , Elementos Facilitadores Genéticos , Amplificação de Genes , Oncogenes , Acetilação , Sistemas CRISPR-Cas/genética , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Cromatina/metabolismo , DNA de Neoplasias/genética , Receptores ErbB/genética , Receptores ErbB/metabolismo , Genes Neoplásicos , Loci Gênicos , Glioblastoma/genética , Glioblastoma/patologia , Histonas/metabolismo , Humanos , Neuroglia/metabolismoRESUMO
Higher eukaryotic chromosomes are organized into topologically constrained functional domains; however, the molecular mechanisms required to sustain these complex interphase chromatin structures are unknown. A stable matrix underpinning nuclear organization was hypothesized, but the idea was abandoned as more dynamic models of chromatin behavior became prevalent. Here, we report that scaffold attachment factor A (SAF-A), originally identified as a structural nuclear protein, interacts with chromatin-associated RNAs (caRNAs) via its RGG domain to regulate human interphase chromatin structures in a transcription-dependent manner. Mechanistically, this is dependent on SAF-A's AAA+ ATPase domain, which mediates cycles of protein oligomerization with caRNAs, in response to ATP binding and hydrolysis. SAF-A oligomerization decompacts large-scale chromatin structure while SAF-A loss or monomerization promotes aberrant chromosome folding and accumulation of genome damage. Our results show that SAF-A and caRNAs form a dynamic, transcriptionally responsive chromatin mesh that organizes large-scale chromosome structures and protects the genome from instability.
Assuntos
Cromossomos/metabolismo , Instabilidade Genômica , Ribonucleoproteínas Nucleares Heterogêneas Grupo U/metabolismo , RNA Nuclear Pequeno/metabolismo , Sequência de Aminoácidos , Cromatina , Células HEK293 , Ribonucleoproteínas Nucleares Heterogêneas Grupo U/química , Humanos , Interfase , Modelos Moleculares , Alinhamento de Sequência , Transcrição GênicaRESUMO
Fine control of macrophage activation is needed to prevent inflammatory disease, particularly at barrier sites such as the lungs. However, the dominant mechanisms that regulate the activation of pulmonary macrophages during inflammation are poorly understood. We found that alveolar macrophages (AlvMs) were much less able to respond to the canonical type 2 cytokine IL-4, which underpins allergic disease and parasitic worm infections, than macrophages from lung tissue or the peritoneal cavity. We found that the hyporesponsiveness of AlvMs to IL-4 depended upon the lung environment but was independent of the host microbiota or the lung extracellular matrix components surfactant protein D (SP-D) and mucin 5b (Muc5b). AlvMs showed severely dysregulated metabolism relative to that of cavity macrophages. After removal from the lungs, AlvMs regained responsiveness to IL-4 in a glycolysis-dependent manner. Thus, impaired glycolysis in the pulmonary niche regulates AlvM responsiveness during type 2 inflammation.
Assuntos
Inflamação/imunologia , Pulmão/imunologia , Ativação de Macrófagos/imunologia , Macrófagos Alveolares/imunologia , Animais , Inflamação/genética , Inflamação/metabolismo , Interleucina-4/genética , Interleucina-4/imunologia , Interleucina-4/metabolismo , Larva/imunologia , Larva/fisiologia , Pulmão/metabolismo , Pulmão/patologia , Ativação de Macrófagos/genética , Macrófagos Alveolares/metabolismo , Macrófagos Alveolares/parasitologia , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Mucina-5B/genética , Mucina-5B/imunologia , Mucina-5B/metabolismo , Nippostrongylus/imunologia , Nippostrongylus/fisiologia , Proteína D Associada a Surfactante Pulmonar/genética , Proteína D Associada a Surfactante Pulmonar/imunologia , Proteína D Associada a Surfactante Pulmonar/metabolismo , Infecções por Strongylida/genética , Infecções por Strongylida/imunologia , Infecções por Strongylida/parasitologiaRESUMO
There has been growing appreciation that transcription is an endogenous source of replication stress and must be coordinated with replication. In this issue, Bhowmick et al.1 uncover a protective mechanism that prevents co-directional transcription-replication conflicts (TRCs) from becoming genotoxic.
Assuntos
Replicação do DNA , Transcrição Gênica , Dano ao DNARESUMO
Zhang et al.1 reveal a previously unknown route to toxin activation whereby bacteriophage capsid proteins bind the antitoxin domain of the CapRel fused toxin-antitoxin system, triggering translational inhibition via pyrophosporylation of tRNAs and culminating in abortive infection-mediated phage resistance.
Assuntos
Antitoxinas , Toxinas Bacterianas , Bacteriófagos , Sistemas Toxina-Antitoxina , Bacteriófagos/metabolismo , Proteínas do Capsídeo/genética , Capsídeo/metabolismo , Bactérias/metabolismo , Antitoxinas/metabolismo , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Proteínas de Bactérias/metabolismoRESUMO
To contend with the diversity and ubiquity of bacteriophages and other mobile genetic elements, bacteria have developed an arsenal of immune defence mechanisms. Bacterial defences include CRISPR-Cas, restriction-modification and a growing list of mechanistically diverse systems, which constitute the bacterial 'immune system'. As a response, bacteriophages and mobile genetic elements have evolved direct and indirect mechanisms to circumvent or block bacterial defence pathways and ensure successful infection. Recent advances in methodological and computational approaches, as well as the increasing availability of genome sequences, have boosted the discovery of direct inhibitors of bacterial defence systems. In this Review, we discuss methods for the discovery of direct inhibitors, their diverse mechanisms of action and perspectives on their emerging applications in biotechnology and beyond.
Assuntos
Bacteriófagos , Sistemas CRISPR-Cas , Bactérias/genética , Bacteriófagos/genéticaRESUMO
In all organisms, regulation of gene expression must be adjusted to meet cellular requirements and frequently involves helix-turn-helix (HTH) domain proteins1. For instance, in the arms race between bacteria and bacteriophages, rapid expression of phage anti-CRISPR (acr) genes upon infection enables evasion from CRISPR-Cas defence; transcription is then repressed by an HTH-domain-containing anti-CRISPR-associated (Aca) protein, probably to reduce fitness costs from excessive expression2-5. However, how a single HTH regulator adjusts anti-CRISPR production to cope with increasing phage genome copies and accumulating acr mRNA is unknown. Here we show that the HTH domain of the regulator Aca2, in addition to repressing Acr synthesis transcriptionally through DNA binding, inhibits translation of mRNAs by binding conserved RNA stem-loops and blocking ribosome access. The cryo-electron microscopy structure of the approximately 40 kDa Aca2-RNA complex demonstrates how the versatile HTH domain specifically discriminates RNA from DNA binding sites. These combined regulatory modes are widespread in the Aca2 family and facilitate CRISPR-Cas inhibition in the face of rapid phage DNA replication without toxic acr overexpression. Given the ubiquity of HTH-domain-containing proteins, it is anticipated that many more of them elicit regulatory control by dual DNA and RNA binding.
Assuntos
Bacteriófagos , Sistemas CRISPR-Cas , Proteínas de Ligação a DNA , Regulação Viral da Expressão Gênica , Sequências Hélice-Volta-Hélice , Proteínas de Ligação a RNA , Proteínas Virais , Bacteriófagos/química , Bacteriófagos/genética , Bacteriófagos/metabolismo , Bacteriófagos/ultraestrutura , Sítios de Ligação , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Proteínas Associadas a CRISPR/metabolismo , Microscopia Crioeletrônica , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/ultraestrutura , Genes Virais , Modelos Moleculares , Conformação de Ácido Nucleico , Pectobacterium carotovorum/virologia , Biossíntese de Proteínas/genética , Domínios Proteicos , Ribossomos/metabolismo , RNA Mensageiro/química , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Mensageiro/ultraestrutura , RNA Viral/química , RNA Viral/genética , RNA Viral/metabolismo , RNA Viral/ultraestrutura , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/ultraestrutura , Especificidade por Substrato , Transcrição Gênica , Proteínas Virais/química , Proteínas Virais/genética , Proteínas Virais/metabolismo , Proteínas Virais/ultraestruturaRESUMO
The brightness of an emitter is ultimately described by Fermi's golden rule, with a radiative rate proportional to its oscillator strength times the local density of photonic states. As the oscillator strength is an intrinsic material property, the quest for ever brighter emission has relied on the local density of photonic states engineering, using dielectric or plasmonic resonators1,2. By contrast, a much less explored avenue is to boost the oscillator strength, and hence the emission rate, using a collective behaviour termed superradiance. Recently, it was proposed3 that the latter can be realized using the giant oscillator-strength transitions of a weakly confined exciton in a quantum well when its coherent motion extends over many unit cells. Here we demonstrate single-photon superradiance in perovskite quantum dots with a sub-100 picosecond radiative decay time, almost as short as the reported exciton coherence time4. The characteristic dependence of radiative rates on the size, composition and temperature of the quantum dot suggests the formation of giant transition dipoles, as confirmed by effective-mass calculations. The results aid in the development of ultrabright, coherent quantum light sources and attest that quantum effects, for example, single-photon emission, persist in nanoparticles ten times larger than the exciton Bohr radius.
RESUMO
Ammonia is crucial as a fertilizer and in the chemical industry and is considered to be a carbon-free fuel1. Ammonia electrosynthesis from nitrogen under ambient conditions offers an attractive alternative to the Haber-Bosch process2,3, and lithium-mediated nitrogen reduction represents a promising approach to continuous-flow ammonia electrosynthesis, coupling nitrogen reduction with hydrogen oxidation4. However, tetrahydrofuran, which is commonly used as a solvent, impedes long-term ammonia production owing to polymerization and volatility problems. Here we show that a chain-ether-based electrolyte enables long-term continuous ammonia synthesis. We find that a chain-ether-based solvent exhibits non-polymerization properties and a high boiling point (162 °C) and forms a compact solid-electrolyte interphase layer on the gas diffusion electrode, facilitating ammonia release in the gas phase and ensuring electrolyte stability. We demonstrate 300 h of continuous operation in a flow electrolyser with a 25 cm2 electrode at 1 bar pressure and room temperature, and achieve a current-to-ammonia efficiency of 64 ± 1% with a gas-phase ammonia content of approximately 98%. Our results highlight the crucial role of the solvent in long-term continuous ammonia synthesis.
RESUMO
Where there is defense, there is counter-defense. A paper by Hobbs et al. (2022) reconfirms that this emerging tenet of the arms race between bacteria and their predators also holds true for phage defense systems that rely on secondary messenger signals.
Assuntos
Bacteriófagos , Bactérias/genética , Bacteriófagos/genéticaRESUMO
Bacteria have diverse defenses against phages. In response, jumbo phages evade multiple DNA-targeting defenses by protecting their DNA inside a nucleus-like structure. We previously demonstrated that RNA-targeting type III CRISPR-Cas systems provide jumbo phage immunity by recognizing viral mRNA exported from the nucleus for translation. Here, we demonstrate that recognition of phage mRNA by the type III system activates a cyclic triadenylate-dependent accessory nuclease, NucC. Although unable to access phage DNA in the nucleus, NucC degrades the bacterial chromosome, triggers cell death, and disrupts phage replication and maturation. Hence, type-III-mediated jumbo phage immunity occurs via abortive infection, with suppression of the viral epidemic protecting the population. We further show that type III systems targeting jumbo phages have diverse accessory nucleases, including RNases that provide immunity. Our study demonstrates how type III CRISPR-Cas systems overcome the inaccessibility of jumbo phage DNA to provide robust immunity.
Assuntos
Bacteriófagos , Bacteriófagos/genética , Sistemas CRISPR-Cas , Núcleo Celular , Cromossomos Bacterianos , Endonucleases , RNA MensageiroRESUMO
Many bacteria use CRISPR-Cas systems to combat mobile genetic elements, such as bacteriophages and plasmids1. In turn, these invasive elements have evolved anti-CRISPR proteins to block host immunity2,3. Here we unveil a distinct type of CRISPR-Cas Inhibition strategy that is based on small non-coding RNA anti-CRISPRs (Racrs). Racrs mimic the repeats found in CRISPR arrays and are encoded in viral genomes as solitary repeat units4. We show that a prophage-encoded Racr strongly inhibits the type I-F CRISPR-Cas system by interacting specifically with Cas6f and Cas7f, resulting in the formation of an aberrant Cas subcomplex. We identified Racr candidates for almost all CRISPR-Cas types encoded by a diverse range of viruses and plasmids, often in the genetic context of other anti-CRISPR genes5. Functional testing of nine candidates spanning the two CRISPR-Cas classes confirmed their strong immune inhibitory function. Our results demonstrate that molecular mimicry of CRISPR repeats is a widespread anti-CRISPR strategy, which opens the door to potential biotechnological applications6.
Assuntos
Bactérias , Bacteriófagos , Sistemas CRISPR-Cas , Mimetismo Molecular , RNA Viral , Bactérias/genética , Bactérias/imunologia , Bactérias/virologia , Bacteriófagos/genética , Bacteriófagos/imunologia , Biotecnologia/métodos , Biotecnologia/tendências , Proteínas Associadas a CRISPR/metabolismo , Sistemas CRISPR-Cas/genética , Sistemas CRISPR-Cas/imunologia , Plasmídeos/genética , Prófagos/genética , Prófagos/imunologia , RNA Viral/genéticaRESUMO
The histone variant H2A.Z is a genome-wide signature of nucleosomes proximal to eukaryotic regulatory DNA. Whereas the multisubunit chromatin remodeler SWR1 is known to catalyze ATP-dependent deposition of H2A.Z, the mechanism of SWR1 recruitment to S. cerevisiae promoters has been unclear. A sensitive assay for competitive binding of dinucleosome substrates revealed that SWR1 preferentially binds long nucleosome-free DNA and the adjoining nucleosome core particle, allowing discrimination of gene promoters over gene bodies. Analysis of mutants indicates that the conserved Swc2/YL1 subunit and the adenosine triphosphatase domain of Swr1 are mainly responsible for binding to substrate. SWR1 binding is enhanced on nucleosomes acetylated by the NuA4 histone acetyltransferase, but recognition of nucleosome-free and nucleosomal DNA is dominant over interaction with acetylated histones. Such hierarchical cooperation between DNA and histone signals expands the dynamic range of genetic switches, unifying classical gene regulation by DNA-binding factors with ATP-dependent nucleosome remodeling and posttranslational histone modifications.
Assuntos
Montagem e Desmontagem da Cromatina , Histonas/metabolismo , Complexos Multiproteicos/metabolismo , Nucleossomos/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Acetilação , Adenosina Trifosfatases/metabolismo , Sequência de Bases , Histona Acetiltransferases/metabolismo , Dados de Sequência Molecular , Processamento de Proteína Pós-Traducional , Saccharomyces cerevisiae/genéticaRESUMO
Kinase suppressor of Ras 2 (KSR2) is an intracellular scaffolding protein involved in multiple signaling pathways. Targeted deletion of Ksr2 leads to obesity in mice, suggesting a role in energy homeostasis. We explored the role of KSR2 in humans by sequencing 2,101 individuals with severe early-onset obesity and 1,536 controls. We identified multiple rare variants in KSR2 that disrupt signaling through the Raf-MEKERK pathway and impair cellular fatty acid oxidation and glucose oxidation in transfected cells; effects that can be ameliorated by the commonly prescribed antidiabetic drug, metformin. Mutation carriers exhibit hyperphagia in childhood, low heart rate, reduced basal metabolic rate and severe insulin resistance. These data establish KSR2 as an important regulator of energy intake, energy expenditure, and substrate utilization in humans. Modulation of KSR2-mediated effects may represent a novel therapeutic strategy for obesity and type 2 diabetes.