RESUMO
Alpha-synuclein (αS) is a conformationally plastic protein that reversibly binds to cellular membranes. It aggregates and is genetically linked to Parkinson's disease (PD). Here, we show that αS directly modulates processing bodies (P-bodies), membraneless organelles that function in mRNA turnover and storage. The N terminus of αS, but not other synucleins, dictates mutually exclusive binding either to cellular membranes or to P-bodies in the cytosol. αS associates with multiple decapping proteins in close proximity on the Edc4 scaffold. As αS pathologically accumulates, aberrant interaction with Edc4 occurs at the expense of physiologic decapping-module interactions. mRNA decay kinetics within PD-relevant pathways are correspondingly disrupted in PD patient neurons and brain. Genetic modulation of P-body components alters αS toxicity, and human genetic analysis lends support to the disease-relevance of these interactions. Beyond revealing an unexpected aspect of αS function and pathology, our data highlight the versatility of conformationally plastic proteins with high intrinsic disorder.
Assuntos
Doença de Parkinson , alfa-Sinucleína , Humanos , Doença de Parkinson/metabolismo , Corpos de Processamento , Estabilidade de RNA , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismoRESUMO
Zinc (Zn) is an essential micronutrient and cofactor for up to 10% of proteins in living organisms. During Zn limitation, specialized enzymes called metallochaperones are predicted to allocate Zn to specific metalloproteins. This function has been putatively assigned to G3E GTPase COG0523 proteins, yet no Zn metallochaperone has been experimentally identified in any organism. Here, we functionally characterize a family of COG0523 proteins that is conserved across vertebrates. We identify Zn metalloprotease methionine aminopeptidase 1 (METAP1) as a COG0523 client, leading to the redesignation of this group of COG0523 proteins as the Zn-regulated GTPase metalloprotein activator (ZNG1) family. Using biochemical, structural, genetic, and pharmacological approaches across evolutionarily divergent models, including zebrafish and mice, we demonstrate a critical role for ZNG1 proteins in regulating cellular Zn homeostasis. Collectively, these data reveal the existence of a family of Zn metallochaperones and assign ZNG1 an important role for intracellular Zn trafficking.
Assuntos
Metaloendopeptidases/metabolismo , Zinco , Animais , GTP Fosfo-Hidrolases/metabolismo , Homeostase , Metalochaperonas/metabolismo , Metaloproteínas/genética , Camundongos , Peixe-Zebra/metabolismo , Zinco/metabolismoRESUMO
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
Thousands of interactions assemble proteins into modules that impart spatial and functional organization to the cellular proteome. Through affinity-purification mass spectrometry, we have created two proteome-scale, cell-line-specific interaction networks. The first, BioPlex 3.0, results from affinity purification of 10,128 human proteins-half the proteome-in 293T cells and includes 118,162 interactions among 14,586 proteins. The second results from 5,522 immunoprecipitations in HCT116 cells. These networks model the interactome whose structure encodes protein function, localization, and complex membership. Comparison across cell lines validates thousands of interactions and reveals extensive customization. Whereas shared interactions reside in core complexes and involve essential proteins, cell-specific interactions link these complexes, "rewiring" subnetworks within each cell's interactome. Interactions covary among proteins of shared function as the proteome remodels to produce each cell's phenotype. Viewable interactively online through BioPlexExplorer, these networks define principles of proteome organization and enable unknown protein characterization.
Assuntos
Mapeamento de Interação de Proteínas/métodos , Mapas de Interação de Proteínas/genética , Proteoma/genética , Biologia Computacional/métodos , Células HCT116/metabolismo , Células HEK293/metabolismo , Humanos , Espectrometria de Massas/métodos , Mapas de Interação de Proteínas/fisiologia , Proteoma/metabolismo , Proteômica/métodosRESUMO
Cells confront DNA damage in every cell cycle. Among the most deleterious types of DNA damage are DNA double-strand breaks (DSBs), which can cause cell lethality if unrepaired or cancers if improperly repaired. In response to DNA DSBs, cells activate a complex DNA damage checkpoint (DDC) response that arrests the cell cycle, reprograms gene expression, and mobilizes DNA repair factors to prevent the inheritance of unrepaired and broken chromosomes. Here we examine the DDC, induced by DNA DSBs, in the budding yeast model system and in mammals.
Assuntos
Pontos de Checagem do Ciclo Celular/genética , Reparo do DNA por Junção de Extremidades , DNA/genética , Reparo de DNA por Recombinação , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Animais , Proteínas Mutadas de Ataxia Telangiectasia/química , Proteínas Mutadas de Ataxia Telangiectasia/genética , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Quinase 1 do Ponto de Checagem/genética , Quinase 1 do Ponto de Checagem/metabolismo , Quinase do Ponto de Checagem 2/genética , Quinase do Ponto de Checagem 2/metabolismo , DNA/química , DNA/metabolismo , Quebras de DNA de Cadeia Dupla , Humanos , Modelos Moleculares , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Estrutura Secundária de Proteína , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
Proteins are essential agents of biological processes. To date, large-scale profiling of cell line collections including the Cancer Cell Line Encyclopedia (CCLE) has focused primarily on genetic information whereas deep interrogation of the proteome has remained out of reach. Here, we expand the CCLE through quantitative profiling of thousands of proteins by mass spectrometry across 375 cell lines from diverse lineages to reveal information undiscovered by DNA and RNA methods. We observe unexpected correlations within and between pathways that are largely absent from RNA. An analysis of microsatellite instable (MSI) cell lines reveals the dysregulation of specific protein complexes associated with surveillance of mutation and translation. These and other protein complexes were associated with sensitivity to knockdown of several different genes. These data in conjunction with the wider CCLE are a broad resource to explore cellular behavior and facilitate cancer research.
Assuntos
Regulação Neoplásica da Expressão Gênica/genética , Neoplasias/metabolismo , Proteoma/metabolismo , Linhagem Celular Tumoral , Perfilação da Expressão Gênica/métodos , Humanos , Espectrometria de Massas/métodos , Instabilidade de Microssatélites , Mutação/genética , Proteômica/métodosRESUMO
Dysfunctional CD8+ T cells, which have defective production of antitumor effectors, represent a major mediator of immunosuppression in the tumor microenvironment. Here, we show that SUSD2 is a negative regulator of CD8+ T cell antitumor function. Susd2-/- effector CD8+ T cells showed enhanced production of antitumor molecules, which consequently blunted tumor growth in multiple syngeneic mouse tumor models. Through a quantitative mass spectrometry assay, we found that SUSD2 interacted with interleukin (IL)-2 receptor α through sushi domain-dependent protein interactions and that this interaction suppressed the binding of IL-2, an essential cytokine for the effector functions of CD8+ T cells, to IL-2 receptor α. SUSD2 was not expressed on regulatory CD4+ T cells and did not affect the inhibitory function of these cells. Adoptive transfer of Susd2-/- chimeric antigen receptor T cells induced a robust antitumor response in mice, highlighting the potential of SUSD2 as an immunotherapy target for cancer.
Assuntos
Linfócitos T CD8-Positivos , Neoplasias , Animais , Camundongos , Linhagem Celular Tumoral , Imunoterapia/métodos , Camundongos Endogâmicos C57BL , Neoplasias/metabolismo , Receptores de Interleucina-2/metabolismo , Transdução de Sinais , Microambiente TumoralRESUMO
Friedreich's ataxia (FRDA) is a devastating, multisystemic disorder caused by recessive mutations in the mitochondrial protein frataxin (FXN). FXN participates in the biosynthesis of Fe-S clusters and is considered to be essential for viability. Here we report that when grown in 1% ambient O2, FXN null yeast, human cells, and nematodes are fully viable. In human cells, hypoxia restores steady-state levels of Fe-S clusters and normalizes ATF4, NRF2, and IRP2 signaling events associated with FRDA. Cellular studies and in vitro reconstitution indicate that hypoxia acts through HIF-independent mechanisms that increase bioavailable iron as well as directly activate Fe-S synthesis. In a mouse model of FRDA, breathing 11% O2 attenuates the progression of ataxia, whereas breathing 55% O2 hastens it. Our work identifies oxygen as a key environmental variable in the pathogenesis associated with FXN depletion, with important mechanistic and therapeutic implications.
Assuntos
Hipóxia/metabolismo , Proteínas de Ligação ao Ferro/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Fator 4 Ativador da Transcrição/metabolismo , Animais , Caenorhabditis elegans/metabolismo , Feminino , Ataxia de Friedreich/metabolismo , Células HEK293 , Humanos , Hipóxia/fisiopatologia , Ferro/metabolismo , Proteína 2 Reguladora do Ferro/metabolismo , Proteínas de Ligação ao Ferro/fisiologia , Proteínas Ferro-Enxofre/fisiologia , Células K562 , Masculino , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Proteínas Mitocondriais/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Estresse Oxidativo , Saccharomyces cerevisiae/metabolismo , Enxofre/metabolismo , FrataxinaRESUMO
Patients with myelodysplastic syndromes (MDSs) display severe anemia but the mechanisms underlying this phenotype are incompletely understood. Right open-reading-frame kinase 2 (RIOK2) encodes a protein kinase located at 5q15, a region frequently lost in patients with MDS del(5q). Here we show that hematopoietic cell-specific haploinsufficient deletion of Riok2 (Riok2f/+Vav1cre) led to reduced erythroid precursor frequency leading to anemia. Proteomic analysis of Riok2f/+Vav1cre erythroid precursors suggested immune system activation, and transcriptomic analysis revealed an increase in p53-dependent interleukin (IL)-22 in Riok2f/+Vav1cre CD4+ T cells (TH22). Further, we discovered that the IL-22 receptor, IL-22RA1, was unexpectedly present on erythroid precursors. Blockade of IL-22 signaling alleviated anemia not only in Riok2f/+Vav1cre mice but also in wild-type mice. Serum concentrations of IL-22 were increased in the subset of patients with del(5q) MDS as well as patients with anemia secondary to chronic kidney disease. This work reveals a possible therapeutic opportunity for reversing many stress-induced anemias by targeting IL-22 signaling.
Assuntos
Anemia/metabolismo , Anticorpos Neutralizantes/farmacologia , Células Eritroides/metabolismo , Eritropoese/efeitos dos fármacos , Interleucinas/antagonistas & inibidores , Síndromes Mielodisplásicas/tratamento farmacológico , Receptores de Interleucina/metabolismo , Anemia/sangue , Anemia/imunologia , Anemia/prevenção & controle , Animais , Células Cultivadas , Microambiente Celular , Modelos Animais de Doenças , Células Eritroides/imunologia , Humanos , Interleucinas/imunologia , Interleucinas/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Síndromes Mielodisplásicas/sangue , Síndromes Mielodisplásicas/imunologia , Síndromes Mielodisplásicas/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-vav/genética , Proteínas Proto-Oncogênicas c-vav/metabolismo , Receptores de Interleucina/genética , Insuficiência Renal Crônica/sangue , Insuficiência Renal Crônica/imunologia , Insuficiência Renal Crônica/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Interleucina 22RESUMO
Aicardi-Goutières syndrome (AGS) is an autoinflammatory disease characterized by aberrant interferon (IFN)-α production. The major cause of morbidity in AGS is brain disease, yet the primary source and target of neurotoxic IFN-α remain unclear. Here, we demonstrated that the brain was the primary source of neurotoxic IFN-α in AGS and confirmed the neurotoxicity of intracerebral IFN-α using astrocyte-driven Ifna1 misexpression in mice. Using single-cell RNA sequencing, we demonstrated that intracerebral IFN-α-activated receptor (IFNAR) signaling within cerebral endothelial cells caused a distinctive cerebral small vessel disease similar to that observed in individuals with AGS. Magnetic resonance imaging (MRI) and single-molecule ELISA revealed that central and not peripheral IFN-α was the primary determinant of microvascular disease in humans. Ablation of endothelial Ifnar1 in mice rescued microvascular disease, stopped the development of diffuse brain disease, and prolonged lifespan. These results identify the cerebral microvasculature as a primary mediator of IFN-α neurotoxicity in AGS, representing an accessible target for therapeutic intervention.
Assuntos
Encéfalo , Interferon-alfa , Microvasos , Malformações do Sistema Nervoso , Receptor de Interferon alfa e beta , Animais , Humanos , Camundongos , Interferon-alfa/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Receptor de Interferon alfa e beta/metabolismo , Receptor de Interferon alfa e beta/genética , Microvasos/patologia , Malformações do Sistema Nervoso/genética , Doenças Autoimunes do Sistema Nervoso/imunologia , Células Endoteliais/metabolismo , Camundongos Knockout , Masculino , Feminino , Transdução de Sinais , Camundongos Endogâmicos C57BL , Astrócitos/metabolismo , Modelos Animais de DoençasRESUMO
MicroRNAs (miRNAs) are â¼22 nt RNAs that direct posttranscriptional repression of mRNA targets in diverse eukaryotic lineages. In humans and other mammals, these small RNAs help sculpt the expression of most mRNAs. This article reviews advances in our understanding of the defining features of metazoan miRNAs and their biogenesis, genomics, and evolution. It then reviews how metazoan miRNAs are regulated, how they recognize and cause repression of their targets, and the biological functions of this repression, with a compilation of knockout phenotypes that shows that important biological functions have been identified for most of the broadly conserved miRNAs of mammals.
Assuntos
MicroRNAs/metabolismo , Animais , Pareamento de Bases , Evolução Molecular , Regulação da Expressão Gênica , Inativação Gênica , Genômica , Humanos , MicroRNAs/antagonistas & inibidores , MicroRNAs/química , Conformação de Ácido Nucleico , Isoformas de RNA/genética , Isoformas de RNA/metabolismoRESUMO
Noncoding RNAs (ncRNAs) play increasingly appreciated gene-regulatory roles. Here, we describe a regulatory network centered on four ncRNAs-a long ncRNA, a circular RNA, and two microRNAs-using gene editing in mice to probe the molecular consequences of disrupting key components of this network. The long ncRNA Cyrano uses an extensively paired site to miR-7 to trigger destruction of this microRNA. Cyrano-directed miR-7 degradation is much more effective than previously described examples of target-directed microRNA degradation, which come primarily from studies of artificial and viral RNAs. By reducing miR-7 levels, Cyrano prevents repression of miR-7-targeted mRNAs and enables accumulation of Cdr1as, a circular RNA known to regulate neuronal activity. Without Cyrano, excess miR-7 causes cytoplasmic destruction of Cdr1as in neurons, in part through enhanced slicing of Cdr1as by a second miRNA, miR-671. Thus, several types of ncRNAs can collaborate to establish a sophisticated regulatory network.
Assuntos
Encéfalo/metabolismo , Redes Reguladoras de Genes , RNA não Traduzido/metabolismo , Animais , Citoplasma/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/genética , MicroRNAs/metabolismo , Neurônios/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismoRESUMO
Hedgehog protein signals mediate tissue patterning and maintenance by binding to and inactivating their common receptor Patched, a 12-transmembrane protein that otherwise would suppress the activity of the 7-transmembrane protein Smoothened. Loss of Patched function, the most common cause of basal cell carcinoma, permits unregulated activation of Smoothened and of the Hedgehog pathway. A cryo-EM structure of the Patched protein reveals striking transmembrane domain similarities to prokaryotic RND transporters. A central hydrophobic conduit with cholesterol-like contents courses through the extracellular domain and resembles that used by other RND proteins to transport substrates, suggesting Patched activity in cholesterol transport. Cholesterol activity in the inner leaflet of the plasma membrane is reduced by PTCH1 expression but rapidly restored by Hedgehog stimulation, suggesting that PTCH1 regulates Smoothened by controlling cholesterol availability.
Assuntos
Colesterol/metabolismo , Proteínas Hedgehog/metabolismo , Receptor Patched-1/metabolismo , Sequência de Aminoácidos , Animais , Linhagem Celular , Microscopia Crioeletrônica , Dimerização , Escherichia coli/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Evolução Molecular , Células HEK293 , Proteínas Hedgehog/química , Proteínas Hedgehog/genética , Humanos , Camundongos , Proteínas Associadas à Resistência a Múltiplos Medicamentos/química , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Receptor Patched-1/química , Receptor Patched-1/genética , Estrutura Terciária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Alinhamento de Sequência , Transdução de SinaisRESUMO
Mucosal-associated invariant T (MAIT) cells are activated by microbial riboflavin-based metabolite antigens when presented by MR1. How modifications to the potent antigen 5-OP-RU affect presentation by MR1 and MAIT cell activation remains unclear. Here we design 20 derivatives, termed altered metabolite ligands (AMLs), to dissect the impact of different antigen components on the human MAIT-MR1 axis. Analysis of 11 crystal structures of MAIT T cell antigen receptor (TCR)-MR1-AML ternary complexes, along with biochemical and functional assays, shows that MR1 cell-surface upregulation is influenced by ribityl and non-ribityl components of the ligand and the hydrophobicity of the MR1-AML interface. The polar ribityl chain of the AML strongly influences MAIT cell activation potency through dynamic compensatory interactions within a MAIT TCR-MR1-AML interaction triad. We define the basis by which the MAIT TCR can differentially recognize AMLs, thereby providing insight into MAIT cell antigen specificity and potency.
Assuntos
Antígenos/imunologia , Células T Invariantes Associadas à Mucosa/imunologia , Linhagem Celular Tumoral , Humanos , Células Jurkat , Ligantes , Ativação Linfocitária/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Riboflavina/imunologiaRESUMO
Engagement of platelet endothelial cell adhesion molecule 1 (PECAM, PECAM-1, CD31) on the leukocyte pseudopod with PECAM at the endothelial cell border initiates transendothelial migration (TEM, diapedesis). We show, using fluorescence lifetime imaging microscopy (FLIM), that physical traction on endothelial PECAM during TEM initiated the endothelial signaling pathway. In this role, endothelial PECAM acted as part of a mechanotransduction complex with VE-cadherin and vascular endothelial growth factor receptor 2 (VEGFR2), and this predicted that VEGFR2 was required for efficient TEM. We show that TEM required both VEGFR2 and the ability of its Y1175 to be phosphorylated, but not VEGF or VEGFR2 endogenous kinase activity. Using inducible endothelial-specific VEGFR2-deficient mice, we show in three mouse models of inflammation that the absence of endothelial VEGFR2 significantly (by ≥75%) reduced neutrophil extravasation by selectively blocking diapedesis. These findings provide a more complete understanding of the process of transmigration and identify several potential anti-inflammatory targets.
Assuntos
Migração Transendotelial e Transepitelial , Receptor 2 de Fatores de Crescimento do Endotélio Vascular , Animais , Camundongos , Adesão Celular , Movimento Celular , Endotélio Vascular , Mecanotransdução Celular , Molécula-1 de Adesão Celular Endotelial a Plaquetas/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
The physiological relevance of structures within mammalian mRNAs has been elusive, as these mRNAs are less folded in cells than in vitro and have predicted secondary structures no more stable than those of random sequences. Here, we investigate the possibility that mRNA structures facilitate the 3'-end processing of thousands of human mRNAs by juxtaposing poly(A) signals (PASs) and cleavage sites that are otherwise too far apart. We find that RNA structures are predicted to be more prevalent within these extended 3'-end regions than within PAS-upstream regions and indeed are substantially more folded within cells, as determined by intracellular probing. Analyses of thousands of ectopically expressed variants demonstrate that this folding both enhances processing and increases mRNA metabolic stability. Even folds with predicted stabilities resembling those of random sequences can enhance processing. Structure-controlled processing can also regulate neighboring gene expression. Thus, RNA structure has widespread roles in mammalian mRNA biogenesis and metabolism.
Assuntos
Poliadenilação , Processamento Pós-Transcricional do RNA , Estabilidade de RNA , RNA Mensageiro/química , RNA Mensageiro/metabolismo , Sequência de Bases , Linhagem Celular , Humanos , Dobramento de RNARESUMO
Intestinal intraepithelial lymphocytes (IELs) are located at the critical interface between the intestinal lumen, which is chronically exposed to food and microbes, and the core of the body. Using high-resolution microscopy techniques and intersectional genetic tools, we investigated the nature of IEL responses to luminal microbes. We observed that TCRγδ IELs exhibit unique microbiota-dependent location and movement patterns in the epithelial compartment. This behavioral pattern quickly changes upon exposure to different enteric pathogens, resulting in increased interepithelial cell (EC) scanning, expression of antimicrobial genes, and glycolysis. Both dynamic and metabolic changes to γδ IEL depend on pathogen sensing by ECs. Direct modulation of glycolysis is sufficient to change γδ IEL behavior and susceptibility to early pathogen invasion. Our results uncover a coordinated EC-IEL response to enteric infections that modulates lymphocyte energy utilization and dynamics and supports maintenance of the intestinal epithelial barrier. VIDEO ABSTRACT.
Assuntos
Intestinos/citologia , Intestinos/imunologia , Infecções por Salmonella/imunologia , Linfócitos T/imunologia , Animais , Células Epiteliais/metabolismo , Vigilância Imunológica , Mucosa Intestinal/imunologia , Camundongos , Infecções por Salmonella/microbiologia , Salmonella typhimurium/fisiologiaRESUMO
The RNA-induced silencing complex (RISC), which powers RNA interference (RNAi), consists of a guide RNA and an Argonaute protein that slices target RNAs complementary to the guide. We find that, for different guide-RNA sequences, slicing rates of perfectly complementary bound targets can be surprisingly different (>250-fold range), and that faster slicing confers better knockdown in cells. Nucleotide sequence identities at guide-RNA positions 7, 10, and 17 underlie much of this variation in slicing rates. Analysis of one of these determinants implicates a structural distortion at guide nucleotides 6-7 in promoting slicing. Moreover, slicing directed by different guide sequences has an unanticipated, 600-fold range in 3'-mismatch tolerance, attributable to guides with weak (AU-rich) central pairing requiring extensive 3' complementarity (pairing beyond position 16) to more fully populate the slicing-competent conformation. Together, our analyses identify sequence determinants of RISC activity and provide biochemical and conformational rationale for their action.
Assuntos
Proteínas Argonautas , Conformação de Ácido Nucleico , RNA Guia de Sistemas CRISPR-Cas , Complexo de Inativação Induzido por RNA , Proteínas Argonautas/metabolismo , Proteínas Argonautas/genética , Proteínas Argonautas/química , Humanos , Complexo de Inativação Induzido por RNA/metabolismo , Complexo de Inativação Induzido por RNA/genética , Complexo de Inativação Induzido por RNA/química , Cinética , RNA Guia de Sistemas CRISPR-Cas/genética , RNA Guia de Sistemas CRISPR-Cas/metabolismo , Interferência de RNA , Sequência de Bases , Células HEK293RESUMO
iRhoms are pseudoprotease members of the rhomboid-like superfamily and are cardinal regulators of inflammatory and growth factor signaling; they function primarily by recognizing transmembrane domains of their clients. Here, we report a mechanistically distinct nuclear function of iRhoms, showing that both human and mouse iRhom2 are non-canonical substrates of signal peptidase complex (SPC), the protease that removes signal peptides from secreted proteins. Cleavage of iRhom2 generates an N-terminal fragment that enters the nucleus and modifies the transcriptome, in part by binding C-terminal binding proteins (CtBPs). The biological significance of nuclear iRhom2 is indicated by elevated levels in skin biopsies of patients with psoriasis, tylosis with oesophageal cancer (TOC), and non-epidermolytic palmoplantar keratoderma (NEPPK); increased iRhom2 cleavage in a keratinocyte model of psoriasis; and nuclear iRhom2 promoting proliferation of keratinocytes. Overall, this work identifies an unexpected SPC-dependent ER-to-nucleus signaling pathway and demonstrates that iRhoms can mediate nuclear signaling.
Assuntos
Psoríase , Transdução de Sinais , Animais , Humanos , Camundongos , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Psoríase/genética , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismoRESUMO
Mutations in the Kv3.3 potassium channel (KCNC3) cause cerebellar neurodegeneration and impair auditory processing. The cytoplasmic C terminus of Kv3.3 contains a proline-rich domain conserved in proteins that activate actin nucleation through Arp2/3. We found that Kv3.3 recruits Arp2/3 to the plasma membrane, resulting in formation of a relatively stable cortical actin filament network resistant to cytochalasin D that inhibits fast barbed end actin assembly. These Kv3.3-associated actin structures are required to prevent very rapid N-type channel inactivation during short depolarizations of the plasma membrane. The effects of Kv3.3 on the actin cytoskeleton are mediated by the binding of the cytoplasmic C terminus of Kv3.3 to Hax-1, an anti-apoptotic protein that regulates actin nucleation through Arp2/3. A human Kv3.3 mutation within a conserved proline-rich domain produces channels that bind Hax-1 but are impaired in recruiting Arp2/3 to the plasma membrane, resulting in growth cones with deficient actin veils in stem cell-derived neurons.