RESUMO
All eukaryotes require intricate protein networks to translate developmental signals into accurate cell fate decisions. Mutations that disturb interactions between network components often result in disease, but how the composition and dynamics of complex networks are established remains poorly understood. Here, we identify the E3 ligase UBR5 as a signaling hub that helps degrade unpaired subunits of multiple transcriptional regulators that act within a network centered on the c-Myc oncoprotein. Biochemical and structural analyses show that UBR5 binds motifs that only become available upon complex dissociation. By rapidly turning over unpaired transcription factor subunits, UBR5 establishes dynamic interactions between transcriptional regulators that allow cells to effectively execute gene expression while remaining receptive to environmental signals. We conclude that orphan quality control plays an essential role in establishing dynamic protein networks, which may explain the conserved need for protein degradation during transcription and offers opportunities to modulate gene expression in disease.
Assuntos
Fatores de Transcrição , Ubiquitina-Proteína Ligases , Humanos , Expressão Gênica , Células HEK293 , Células HeLa , Mutação , Transdução de Sinais , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Proper regulation of protein degradation is essential for cell physiology. In the current issue of Cell, Baek et al. elucidated how a large class of ubiquitin ligase, known as CRL, is assembled and disassembled through a key regulator, CAND1.
Assuntos
Fatores de Transcrição , Ubiquitina-Proteína Ligases , Proteínas Culina/metabolismo , Proteólise , Fatores de Transcrição/metabolismo , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Cells respond to environmental cues by remodeling their inventories of multiprotein complexes. Cellular repertoires of SCF (SKP1-CUL1-F box protein) ubiquitin ligase complexes, which mediate much protein degradation, require CAND1 to distribute the limiting CUL1 subunit across the family of â¼70 different F box proteins. Yet, how a single factor coordinately assembles numerous distinct multiprotein complexes remains unknown. We obtained cryo-EM structures of CAND1-bound SCF complexes in multiple states and correlated mutational effects on structures, biochemistry, and cellular assays. The data suggest that CAND1 clasps idling catalytic domains of an inactive SCF, rolls around, and allosterically rocks and destabilizes the SCF. New SCF production proceeds in reverse, through SKP1-F box allosterically destabilizing CAND1. The CAND1-SCF conformational ensemble recycles CUL1 from inactive complexes, fueling mixing and matching of SCF parts for E3 activation in response to substrate availability. Our data reveal biogenesis of a predominant family of E3 ligases, and the molecular basis for systemwide multiprotein complex assembly.
Assuntos
Proteínas Culina , Proteínas F-Box , Proteínas Ligases SKP Culina F-Box , Fatores de Transcrição , Humanos , Proteínas Culina/química , Proteínas Culina/metabolismo , Proteínas F-Box/metabolismo , Conformação Molecular , Proteínas Ligases SKP Culina F-Box/química , Proteínas Ligases SKP Culina F-Box/metabolismo , Fatores de Transcrição/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Ribosomes frequently stall during mRNA translation, resulting in the context-dependent activation of quality control pathways to maintain proteostasis. However, surveillance mechanisms that specifically respond to stalled ribosomes with an occluded A site have not been identified. We discovered that the elongation factor-1α (eEF1A) inhibitor, ternatin-4, triggers the ubiquitination and degradation of eEF1A on stalled ribosomes. Using a chemical genetic approach, we unveiled a signaling network comprising two E3 ligases, RNF14 and RNF25, which are required for eEF1A degradation. Quantitative proteomics revealed the RNF14 and RNF25-dependent ubiquitination of eEF1A and a discrete set of ribosomal proteins. The ribosome collision sensor GCN1 plays an essential role by engaging RNF14, which directly ubiquitinates eEF1A. The site-specific, RNF25-dependent ubiquitination of the ribosomal protein RPS27A/eS31 provides a second essential signaling input. Our findings illuminate a ubiquitin signaling network that monitors the ribosomal A site and promotes the degradation of stalled translation factors, including eEF1A and the termination factor eRF1.
Assuntos
Proteínas de Ligação a RNA , Transativadores , Proteínas de Transporte/metabolismo , Fatores de Alongamento de Peptídeos/genética , Biossíntese de Proteínas , Proteínas Ribossômicas/metabolismo , Ribossomos/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitinação , Humanos , Células HeLa , Células HEK293 , Proteínas de Ligação a RNA/metabolismo , Transativadores/metabolismo , Fator 1 de Elongação de Peptídeos/metabolismoRESUMO
Methods to direct the degradation of protein targets with proximity-inducing molecules that coopt the cellular degradation machinery are advancing in leaps and bounds, and diverse modalities are emerging. The most used and well-studied approach is to hijack E3 ligases of the ubiquitin-proteasome system. E3 ligases use specific molecular recognition to determine which proteins in the cell are ubiquitinated and degraded. This review focuses on the structural determinants of E3 ligase recruitment of natural substrates and neo-substrates obtained through monovalent molecular glues and bivalent proteolysis-targeting chimeras. We use structures to illustrate the different types of substrate recognition and assess the basis for neo-protein-protein interactions in ternary complex structures. The emerging structural and mechanistic complexity is reflective of the diverse physiological roles of protein ubiquitination. This molecular insight is also guiding the application of structure-based design approaches to the development of new and existing degraders as chemical tools and therapeutics.
Assuntos
Ubiquitina-Proteína Ligases , Ubiquitina , Proteínas/metabolismo , Proteólise , Especificidade por Substrato , Ubiquitina/genética , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , UbiquitinaçãoRESUMO
Cullin-RING ubiquitin ligases (CRLs) are dynamic modular platforms that regulate myriad biological processes through target-specific ubiquitylation. Our knowledge of this system emerged from the F-box hypothesis, posited a quarter century ago: Numerous interchangeable F-box proteins confer specific substrate recognition for a core CUL1-based RING E3 ubiquitin ligase. This paradigm has been expanded through the evolution of a superfamily of analogous modular CRLs, with five major families and over 200 different substrate-binding receptors in humans. Regulation is achieved by numerous factors organized in circuits that dynamically control CRL activation and substrate ubiquitylation. CRLs also serve as a vast landscape for developing small molecules that reshape interactions and promote targeted ubiquitylation-dependent turnover of proteins of interest. Here, we review molecular principles underlying CRL function, the role of allosteric and conformational mechanisms in controlling substrate timing and ubiquitylation, and how the dynamics of substrate receptor interchange drives the turnover of selected target proteins to promote cellular decision-making.
Assuntos
Proteínas Culina/química , Proteínas Culina/metabolismo , Proteínas F-Box/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Proteínas F-Box/química , Retroalimentação Fisiológica , Interações Hospedeiro-Patógeno/fisiologia , Humanos , Proteína NEDD8/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Domínios Proteicos , Processamento de Proteína Pós-Traducional , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/química , UbiquitinaçãoRESUMO
Cellular versatility depends on accurate trafficking of diverse proteins to their organellar destinations. For the secretory pathway (followed by approximately 30% of all proteins), the physical nature of the vessel conducting the first portage (endoplasmic reticulum [ER] to Golgi apparatus) is unclear. We provide a dynamic 3D view of early secretory compartments in mammalian cells with isotropic resolution and precise protein localization using whole-cell, focused ion beam scanning electron microscopy with cryo-structured illumination microscopy and live-cell synchronized cargo release approaches. Rather than vesicles alone, the ER spawns an elaborate, interwoven tubular network of contiguous lipid bilayers (ER exit site) for protein export. This receptacle is capable of extending microns along microtubules while still connected to the ER by a thin neck. COPII localizes to this neck region and dynamically regulates cargo entry from the ER, while COPI acts more distally, escorting the detached, accelerating tubular entity on its way to joining the Golgi apparatus through microtubule-directed movement.
Assuntos
Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Microtúbulos/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Transporte Biológico Ativo , Células HeLa , Humanos , Transporte ProteicoRESUMO
Plant immunity is activated upon pathogen perception and often affects growth and yield when it is constitutively active. How plants fine-tune immune homeostasis in their natural habitats remains elusive. Here, we discover a conserved immune suppression network in cereals that orchestrates immune homeostasis, centering on a Ca2+-sensor, RESISTANCE OF RICE TO DISEASES1 (ROD1). ROD1 promotes reactive oxygen species (ROS) scavenging by stimulating catalase activity, and its protein stability is regulated by ubiquitination. ROD1 disruption confers resistance to multiple pathogens, whereas a natural ROD1 allele prevalent in indica rice with agroecology-specific distribution enhances resistance without yield penalty. The fungal effector AvrPiz-t structurally mimics ROD1 and activates the same ROS-scavenging cascade to suppress host immunity and promote virulence. We thus reveal a molecular framework adopted by both host and pathogen that integrates Ca2+ sensing and ROS homeostasis to suppress plant immunity, suggesting a principle for breeding disease-resistant, high-yield crops.
Assuntos
Cálcio/metabolismo , Sequestradores de Radicais Livres/metabolismo , Proteínas Fúngicas/metabolismo , Oryza/imunologia , Imunidade Vegetal , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sistemas CRISPR-Cas/genética , Membrana Celular/metabolismo , Resistência à Doença/genética , Modelos Biológicos , Oryza/genética , Doenças das Plantas/imunologia , Proteínas de Plantas/genética , Ligação Proteica , Estabilidade Proteica , Reprodução , Especificidade da Espécie , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitinação , Zea mays/imunologiaRESUMO
To control viral infection, vertebrates rely on both inducible interferon responses and less well-characterized cell-intrinsic responses composed of "at the ready" antiviral effector proteins. Here, we show that E3 ubiquitin ligase TRIM7 is a cell-intrinsic antiviral effector that restricts multiple human enteroviruses by targeting viral 2BC, a membrane remodeling protein, for ubiquitination and proteasome-dependent degradation. Selective pressure exerted by TRIM7 results in emergence of a TRIM7-resistant coxsackievirus with a single point mutation in the viral 2C ATPase/helicase. In cultured cells, the mutation helps the virus evade TRIM7 but impairs optimal viral replication, and this correlates with a hyperactive and structurally plastic 2C ATPase. Unexpectedly, the TRIM7-resistant virus has a replication advantage in mice and causes lethal pancreatitis. These findings reveal a unique mechanism for targeting enterovirus replication and provide molecular insight into the benefits and trade-offs of viral evolution imposed by a host restriction factor.
Assuntos
Enterovirus/fisiologia , Enterovirus/patogenicidade , Proteínas com Motivo Tripartido/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Replicação Viral/fisiologia , Adenosina Trifosfatases/metabolismo , Animais , Linhagem Celular , Feminino , Humanos , Inflamação/patologia , Camundongos Endogâmicos C57BL , Mutação/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Proteólise , RNA Viral/metabolismo , Ubiquitina/metabolismo , Proteínas Virais/genéticaRESUMO
Despite remarkable clinical efficacy of immune checkpoint blockade (ICB) in cancer treatment, ICB benefits for triple-negative breast cancer (TNBC) remain limited. Through pooled in vivo CRISPR knockout (KO) screens in syngeneic TNBC mouse models, we found that deletion of the E3 ubiquitin ligase Cop1 in cancer cells decreases secretion of macrophage-associated chemokines, reduces tumor macrophage infiltration, enhances anti-tumor immunity, and strengthens ICB response. Transcriptomics, epigenomics, and proteomics analyses revealed that Cop1 functions through proteasomal degradation of the C/ebpδ protein. The Cop1 substrate Trib2 functions as a scaffold linking Cop1 and C/ebpδ, which leads to polyubiquitination of C/ebpδ. In addition, deletion of the E3 ubiquitin ligase Cop1 in cancer cells stabilizes C/ebpδ to suppress expression of macrophage chemoattractant genes. Our integrated approach implicates Cop1 as a target for improving cancer immunotherapy efficacy in TNBC by regulating chemokine secretion and macrophage infiltration in the tumor microenvironment.
Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Imunoterapia , Macrófagos/enzimologia , Neoplasias/imunologia , Neoplasias/terapia , Proteínas Nucleares/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Animais , Proteína delta de Ligação ao Facilitador CCAAT/metabolismo , Proteína 9 Associada à CRISPR/metabolismo , Linhagem Celular Tumoral , Quimiocinas/metabolismo , Quimiotaxia , Modelos Animais de Doenças , Biblioteca Gênica , Humanos , Evasão da Resposta Imune , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Proteólise , Especificidade por Substrato , Neoplasias de Mama Triplo Negativas/imunologia , Neoplasias de Mama Triplo Negativas/terapiaRESUMO
Mutations in DNA damage response (DDR) genes endanger genome integrity and predispose to cancer and genetic disorders. Here, using CRISPR-dependent cytosine base editing screens, we identify > 2,000 sgRNAs that generate nucleotide variants in 86 DDR genes, resulting in altered cellular fitness upon DNA damage. Among those variants, we discover loss- and gain-of-function mutants in the Tudor domain of the DDR regulator 53BP1 that define a non-canonical surface required for binding the deubiquitinase USP28. Moreover, we characterize variants of the TRAIP ubiquitin ligase that define a domain, whose loss renders cells resistant to topoisomerase I inhibition. Finally, we identify mutations in the ATM kinase with opposing genome stability phenotypes and loss-of-function mutations in the CHK2 kinase previously categorized as variants of uncertain significance for breast cancer. We anticipate that this resource will enable the discovery of additional DDR gene functions and expedite studies of DDR variants in human disease.
Assuntos
Dano ao DNA , Edição de Genes , Testes Genéticos , Sequência de Aminoácidos , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Sequência de Bases , Sistemas CRISPR-Cas/genética , Camptotecina/farmacologia , Linhagem Celular , Dano ao DNA/genética , Reparo do DNA/genética , Feminino , Humanos , Mutação/genética , Fenótipo , Ligação Proteica , Domínios Proteicos , RNA Guia de Cinetoplastídeos/genética , Inibidores da Topoisomerase/farmacologia , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/química , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/genética , Ubiquitina Tiolesterase/metabolismo , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Stalled protein synthesis produces defective nascent chains that can harm cells. In response, cells degrade these nascent chains via a process called ribosome-associated quality control (RQC). Here, we review the irregularities in the translation process that cause ribosomes to stall as well as how cells use RQC to detect stalled ribosomes, ubiquitylate their tethered nascent chains, and deliver the ubiquitylated nascent chains to the proteasome. We additionally summarize how cells respond to RQC failure.
Assuntos
Escherichia coli/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Biossíntese de Proteínas , Processamento de Proteína Pós-Traducional , Ribossomos/genética , Escherichia coli/metabolismo , Humanos , Modelos Moleculares , Poli A/química , Poli A/genética , Poli A/metabolismo , Complexo de Endopeptidases do Proteassoma/genética , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Estrutura Secundária de Proteína , Proteólise , Splicing de RNA , Estabilidade de RNA , Ribossomos/metabolismo , Ribossomos/ultraestrutura , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , UbiquitinaçãoRESUMO
Our understanding of the ubiquitin code has greatly evolved from conventional E1, E2 and E3 enzymes that modify Lys residues on specific substrates with a single type of ubiquitin chain to more complex processes that regulate and mediate ubiquitylation. In this Review, we discuss recently discovered endogenous mechanisms and unprecedented pathways by which pathogens rewrite the ubiquitin code to promote infection. These processes include unconventional ubiquitin modifications involving ester linkages with proteins, lipids and sugars, or ubiquitylation through a phosphoribosyl bridge involving Arg42 of ubiquitin. We also introduce the enzymatic pathways that write and reverse these modifications, such as the papain-like proteases of severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2. Furthermore, structural studies have revealed that the ultimate functions of ubiquitin are mediated not simply by straightforward recognition by ubiquitin-binding domains. Instead, elaborate multivalent interactions between ubiquitylated targets or ubiquitin chains and their readers (for example, the proteasome, the MLL1 complex or DOT1L) can elicit conformational changes that regulate protein degradation or transcription. The newly discovered mechanisms provide opportunities for innovative therapeutic interventions for diseases such as cancer and infectious diseases.
Assuntos
COVID-19 , Ubiquitina , Humanos , Ubiquitina/metabolismo , SARS-CoV-2 , Ubiquitinação , Proteínas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismoRESUMO
New biological tools provide new techniques to probe fundamental biological processes. Here we describe the burgeoning field of proteolysis-targeting chimeras (PROTACs), which are capable of modulating protein concentrations at a post-translational level by co-opting the ubiquitin-proteasome system. We describe the PROTAC technology and its application to drug discovery and provide examples where PROTACs have enabled novel biological insights. Furthermore, we provide a workflow for PROTAC development and use and discuss the benefits and issues associated with PROTACs. Finally, we compare PROTAC-mediated protein-level modulation with other technologies, such as RNAi and genome editing.
Assuntos
Descoberta de Drogas , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteólise , Ubiquitina-Proteína Ligases/metabolismo , HumanosRESUMO
Targeted protein degradation (TPD) refers to the use of small molecules to induce ubiquitin-dependent degradation of proteins. TPD is of interest in drug development, as it can address previously inaccessible targets. However, degrader discovery and optimization remains an inefficient process due to a lack of understanding of the relative importance of the key molecular events required to induce target degradation. Here, we use chemo-proteomics to annotate the degradable kinome. Our expansive dataset provides chemical leads for â¼200 kinases and demonstrates that the current practice of starting from the highest potency binder is an ineffective method for discovering active compounds. We develop multitargeted degraders to answer fundamental questions about the ubiquitin proteasome system, uncovering that kinase degradation is p97 dependent. This work will not only fuel kinase degrader discovery, but also provides a blueprint for evaluating targeted degradation across entire gene families to accelerate understanding of TPD beyond the kinome.
Assuntos
Proteínas Quinases/metabolismo , Proteólise , Proteoma/metabolismo , Adulto , Linhagem Celular , Bases de Dados de Proteínas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteínas Quinases/genética , Proteômica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Adulto JovemRESUMO
Metazoan organisms rely on conserved stress response pathways to alleviate adverse conditions and preserve cellular integrity. Stress responses are particularly important in stem cells that provide lifetime support for tissue formation and repair, but how these protective systems are integrated into developmental programs is poorly understood. Here we used myoblast differentiation to identify the E3 ligase CUL2FEM1B and its substrate FNIP1 as core components of the reductive stress response. Reductive stress, as caused by prolonged antioxidant signaling or mitochondrial inactivity, reverts the oxidation of invariant Cys residues in FNIP1 and allows CUL2FEM1B to recognize its target. The ensuing proteasomal degradation of FNIP1 restores mitochondrial activity to preserve redox homeostasis and stem cell integrity. The reductive stress response is therefore built around a ubiquitin-dependent rheostat that tunes mitochondrial activity to redox needs and implicates metabolic control in coordination of stress and developmental signaling.
Assuntos
Proteínas de Transporte/metabolismo , Estresse Oxidativo/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Antioxidantes/metabolismo , Proteínas de Transporte/genética , Diferenciação Celular , Células HEK293 , Homeostase , Humanos , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Mitocôndrias , Desenvolvimento Muscular/fisiologia , Mioblastos/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Transdução de Sinais , Ubiquitina-Proteína Ligases/metabolismo , UbiquitinaçãoRESUMO
Dysregulated microglia are intimately involved in neurodegeneration, including Alzheimer's disease (AD) pathogenesis, but the mechanisms controlling pathogenic microglial gene expression remain poorly understood. The transcription factor CCAAT/enhancer binding protein beta (c/EBPß) regulates pro-inflammatory genes in microglia and is upregulated in AD. We show expression of c/EBPß in microglia is regulated post-translationally by the ubiquitin ligase COP1 (also called RFWD2). In the absence of COP1, c/EBPß accumulates rapidly and drives a potent pro-inflammatory and neurodegeneration-related gene program, evidenced by increased neurotoxicity in microglia-neuronal co-cultures. Antibody blocking studies reveal that neurotoxicity is almost entirely attributable to complement. Remarkably, loss of a single allele of Cebpb prevented the pro-inflammatory phenotype. COP1-deficient microglia markedly accelerated tau-mediated neurodegeneration in a mouse model where activated microglia play a deleterious role. Thus, COP1 is an important suppressor of pathogenic c/EBPß-dependent gene expression programs in microglia.
Assuntos
Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Ligases/metabolismo , Microglia/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina/genética , Doença de Alzheimer/metabolismo , Animais , Linhagem Celular , Técnicas de Cocultura/métodos , Feminino , Expressão Gênica/fisiologia , Regulação da Expressão Gênica/fisiologia , Células HEK293 , Humanos , Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/metabolismoRESUMO
Electrophilic compounds originating from nature or chemical synthesis have profound effects on immune cells. These compounds are thought to act by cysteine modification to alter the functions of immune-relevant proteins; however, our understanding of electrophile-sensitive cysteines in the human immune proteome remains limited. Here, we present a global map of cysteines in primary human T cells that are susceptible to covalent modification by electrophilic small molecules. More than 3,000 covalently liganded cysteines were found on functionally and structurally diverse proteins, including many that play fundamental roles in immunology. We further show that electrophilic compounds can impair T cell activation by distinct mechanisms involving the direct functional perturbation and/or degradation of proteins. Our findings reveal a rich content of ligandable cysteines in human T cells and point to electrophilic small molecules as a fertile source for chemical probes and ultimately therapeutics that modulate immunological processes and their associated disorders.
Assuntos
Cisteína/metabolismo , Ligantes , Linfócitos T/metabolismo , Acetamidas/química , Acetamidas/farmacologia , Acrilamidas/química , Acrilamidas/farmacologia , Células Cultivadas , Humanos , Proteínas Inibidoras de Apoptose/metabolismo , Ativação Linfocitária/efeitos dos fármacos , Proteínas Tirosina Quinases/metabolismo , Proteólise/efeitos dos fármacos , Proteoma/química , Proteoma/metabolismo , Estereoisomerismo , Linfócitos T/citologia , Linfócitos T/imunologia , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Mutations in the BRCA1 and BRCA2 genes predispose afflicted individuals to breast, ovarian, and other cancers. The BRCA-encoded products form complexes with other tumor suppressor proteins and with the recombinase enzyme RAD51 to mediate chromosome damage repair by homologous recombination and also to protect stressed DNA replication forks against spurious nucleolytic attrition. Understanding how the BRCA tumor suppressor network executes its biological functions would provide the foundation for developing targeted cancer therapeutics, but progress in this area has been greatly hampered by the challenge of obtaining purified BRCA complexes for mechanistic studies. In this article, we review how recent effort begins to overcome this technical challenge, leading to functional and structural insights into the biochemical attributes of these complexes and the multifaceted roles that they fulfill in genome maintenance. We also highlight the major mechanistic questions that remain.
Assuntos
Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/genética , Redes Reguladoras de Genes , Rad51 Recombinase/genética , Reparo de DNA por Recombinação , Proteínas Supressoras de Tumor/genética , Ubiquitina-Proteína Ligases/genética , Proteína BRCA1/química , Proteína BRCA1/metabolismo , Proteína BRCA2/química , Proteína BRCA2/metabolismo , Sítios de Ligação , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , DNA/química , DNA/genética , DNA/metabolismo , Quebras de DNA de Cadeia Dupla , Replicação do DNA , Feminino , Genoma Humano , Instabilidade Genômica , Humanos , Modelos Moleculares , Ligação Proteica , Estrutura Secundária de Proteína , Rad51 Recombinase/química , Rad51 Recombinase/metabolismo , Proteínas Supressoras de Tumor/química , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina-Proteína Ligases/química , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Mammalian development demands precision. Millions of molecules must be properly located in temporal order, and their function regulated, to orchestrate important steps in cell cycle progression, apoptosis, migration and differentiation, to shape developing embryos. Ubiquitin and its associated enzymes act as cellular guardians to ensure precise spatio-temporal control of key molecules during each of these important cellular processes. Loss of precision results in numerous examples of embryological disorders or even cancer. This Review discusses the crucial roles of E3 ubiquitin ligases during key steps of early mammalian development and their roles in human disease, and considers how new methods to manipulate and exploit the ubiquitin regulatory machinery - for example, the development of molecular glues and PROTACs - might facilitate clinical therapy.