RESUMEN
Neuroimmune interactions mediate intercellular communication and underlie critical brain functions. Microglia, CNS-resident macrophages, modulate the brain through direct physical interactions and the secretion of molecules. One such secreted factor, the complement protein C1q, contributes to complement-mediated synapse elimination in both developmental and disease models, yet brain C1q protein levels increase significantly throughout aging. Here, we report that C1q interacts with neuronal ribonucleoprotein (RNP) complexes in an age-dependent manner. Purified C1q protein undergoes RNA-dependent liquid-liquid phase separation (LLPS) in vitro, and the interaction of C1q with neuronal RNP complexes in vivo is dependent on RNA and endocytosis. Mice lacking C1q have age-specific alterations in neuronal protein synthesis in vivo and impaired fear memory extinction. Together, our findings reveal a biophysical property of C1q that underlies RNA- and age-dependent neuronal interactions and demonstrate a role of C1q in critical intracellular neuronal processes.
Asunto(s)
Envejecimiento , Encéfalo , Complemento C1q , Homeostasis , Microglía , Neuronas , Ribonucleoproteínas , Animales , Complemento C1q/metabolismo , Ratones , Microglía/metabolismo , Envejecimiento/metabolismo , Encéfalo/metabolismo , Ribonucleoproteínas/metabolismo , Neuronas/metabolismo , Ratones Endogámicos C57BL , HumanosRESUMEN
Type 2 diabetes (T2D) affects Latinos at twice the rate seen in populations of European descent. We recently identified a risk haplotype spanning SLC16A11 that explains â¼20% of the increased T2D prevalence in Mexico. Here, through genetic fine-mapping, we define a set of tightly linked variants likely to contain the causal allele(s). We show that variants on the T2D-associated haplotype have two distinct effects: (1) decreasing SLC16A11 expression in liver and (2) disrupting a key interaction with basigin, thereby reducing cell-surface localization. Both independent mechanisms reduce SLC16A11 function and suggest SLC16A11 is the causal gene at this locus. To gain insight into how SLC16A11 disruption impacts T2D risk, we demonstrate that SLC16A11 is a proton-coupled monocarboxylate transporter and that genetic perturbation of SLC16A11 induces changes in fatty acid and lipid metabolism that are associated with increased T2D risk. Our findings suggest that increasing SLC16A11 function could be therapeutically beneficial for T2D. VIDEO ABSTRACT.
Asunto(s)
Diabetes Mellitus Tipo 2/metabolismo , Transportadores de Ácidos Monocarboxílicos/genética , Transportadores de Ácidos Monocarboxílicos/metabolismo , Basigina/metabolismo , Membrana Celular/metabolismo , Cromosomas Humanos Par 17/metabolismo , Técnicas de Silenciamiento del Gen , Haplotipos , Hepatocitos/metabolismo , Heterocigoto , Código de Histonas , Humanos , Hígado/metabolismo , Modelos Moleculares , Transportadores de Ácidos Monocarboxílicos/químicaRESUMEN
The mechanism by which cells decide to skip mitosis to become polyploid is largely undefined. Here we used a high-content image-based screen to identify small-molecule probes that induce polyploidization of megakaryocytic leukemia cells and serve as perturbagens to help understand this process. Our study implicates five networks of kinases that regulate the switch to polyploidy. Moreover, we find that dimethylfasudil (diMF, H-1152P) selectively increased polyploidization, mature cell-surface marker expression, and apoptosis of malignant megakaryocytes. An integrated target identification approach employing proteomic and shRNA screening revealed that a major target of diMF is Aurora kinase A (AURKA). We further find that MLN8237 (Alisertib), a selective inhibitor of AURKA, induced polyploidization and expression of mature megakaryocyte markers in acute megakaryocytic leukemia (AMKL) blasts and displayed potent anti-AMKL activity in vivo. Our findings provide a rationale to support clinical trials of MLN8237 and other inducers of polyploidization and differentiation in AMKL.
Asunto(s)
Azepinas/farmacología , Descubrimiento de Drogas , Leucemia Megacarioblástica Aguda/tratamiento farmacológico , Megacariocitos/metabolismo , Poliploidía , Pirimidinas/farmacología , Bibliotecas de Moléculas Pequeñas , 1-(5-Isoquinolinesulfonil)-2-Metilpiperazina/análogos & derivados , 1-(5-Isoquinolinesulfonil)-2-Metilpiperazina/farmacología , Animales , Aurora Quinasa A , Aurora Quinasas , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Humanos , Leucemia Megacarioblástica Aguda/genética , Megacariocitos/citología , Megacariocitos/patología , Ratones , Ratones Endogámicos C57BL , Mapas de Interacción de Proteínas , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/metabolismo , Quinasas Asociadas a rho/metabolismoRESUMEN
Chromosomal rearrangements resulting in the fusion of TMPRSS2, an androgen-regulated gene, and the ETS family transcription factor ERG occur in over half of prostate cancers. However, the mechanism by which ERG promotes oncogenic gene expression and proliferation remains incompletely understood. Here, we identify a binding interaction between ERG and the mammalian SWI/SNF (BAF) ATP-dependent chromatin remodeling complex, which is conserved among other oncogenic ETS factors, including ETV1, ETV4, and ETV5. We find that ERG drives genome-wide retargeting of BAF complexes in a manner dependent on binding of ERG to the ETS DNA motif. Moreover, ERG requires intact BAF complexes for chromatin occupancy and BAF complex ATPase activity for target gene regulation. In a prostate organoid model, BAF complexes are required for ERG-mediated basal-to-luminal transition, a hallmark of ERG activity in prostate cancer. These observations suggest a fundamental interdependence between ETS transcription factors and BAF chromatin remodeling complexes in cancer.
Asunto(s)
Carcinogénesis/genética , Proteínas de Unión al ADN/genética , Regulación Neoplásica de la Expresión Génica , Proteínas Nucleares/genética , Proteínas de Fusión Oncogénica/genética , Neoplasias de la Próstata/genética , Serina Endopeptidasas/genética , Proteínas E1A de Adenovirus/genética , Proteínas E1A de Adenovirus/metabolismo , Animales , Sitios de Unión , Línea Celular Tumoral , Proliferación Celular , Cromatina/química , Cromatina/metabolismo , Ensamble y Desensamble de Cromatina , ADN/genética , ADN/metabolismo , Proteínas de Unión al ADN/metabolismo , Células HEK293 , Humanos , Masculino , Ratones Transgénicos , Proteínas Nucleares/metabolismo , Proteínas de Fusión Oncogénica/metabolismo , Organoides/metabolismo , Organoides/patología , Próstata/metabolismo , Próstata/patología , Neoplasias de la Próstata/metabolismo , Neoplasias de la Próstata/patología , Unión Proteica , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-ets , Serina Endopeptidasas/metabolismo , Transducción de Señal , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Regulador Transcripcional ERG/genética , Regulador Transcripcional ERG/metabolismoRESUMEN
RNA-protein interactions determine the cellular fate of RNA and are central to regulating gene expression outcomes in health and disease. To date, no method exists that is able to identify proteins that interact with specific regions within endogenous RNAs in live cells. Here, we develop SHIFTR (Selective RNase H-mediated interactome framing for target RNA regions), an efficient and scalable approach to identify proteins bound to selected regions within endogenous RNAs using mass spectrometry. Compared to state-of-the-art techniques, SHIFTR is superior in accuracy, captures minimal background interactions and requires orders of magnitude lower input material. We establish SHIFTR workflows for targeting RNA classes of different length and abundance, including short and long non-coding RNAs, as well as mRNAs and demonstrate that SHIFTR is compatible with sequentially mapping interactomes for multiple target RNAs in a single experiment. Using SHIFTR, we comprehensively identify interactions of cis-regulatory elements located at the 5' and 3'-terminal regions of authentic SARS-CoV-2 RNAs in infected cells and accurately recover known and novel interactions linked to the function of these viral RNA elements. SHIFTR enables the systematic mapping of region-resolved RNA interactomes for any RNA in any cell type and has the potential to revolutionize our understanding of transcriptomes and their regulation.
Asunto(s)
Proteómica , Proteínas de Unión al ARN , ARN , Programas Informáticos , ARN Largo no Codificante/genética , ARN Mensajero/metabolismo , ARN Viral/genética , Transcriptoma , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo , ARN/química , ARN/metabolismo , Proteómica/métodosRESUMEN
Synthetic lethality-an interaction between two genetic events through which the co-occurrence of these two genetic events leads to cell death, but each event alone does not-can be exploited for cancer therapeutics1. DNA repair processes represent attractive synthetic lethal targets, because many cancers exhibit an impairment of a DNA repair pathway, which can lead to dependence on specific repair proteins2. The success of poly(ADP-ribose) polymerase 1 (PARP-1) inhibitors in cancers with deficiencies in homologous recombination highlights the potential of this approach3. Hypothesizing that other DNA repair defects would give rise to synthetic lethal relationships, we queried dependencies in cancers with microsatellite instability (MSI), which results from deficient DNA mismatch repair. Here we analysed data from large-scale silencing screens using CRISPR-Cas9-mediated knockout and RNA interference, and found that the RecQ DNA helicase WRN was selectively essential in MSI models in vitro and in vivo, yet dispensable in models of cancers that are microsatellite stable. Depletion of WRN induced double-stranded DNA breaks and promoted apoptosis and cell cycle arrest selectively in MSI models. MSI cancer models required the helicase activity of WRN, but not its exonuclease activity. These findings show that WRN is a synthetic lethal vulnerability and promising drug target for MSI cancers.
Asunto(s)
Inestabilidad de Microsatélites , Repeticiones de Microsatélite/genética , Neoplasias/genética , Mutaciones Letales Sintéticas/genética , Helicasa del Síndrome de Werner/genética , Apoptosis/genética , Sistemas CRISPR-Cas/genética , Puntos de Control del Ciclo Celular/genética , Línea Celular Tumoral , Roturas del ADN de Doble Cadena , Humanos , Modelos Genéticos , Neoplasias/patología , Interferencia de ARN , Proteína p53 Supresora de Tumor/metabolismo , Helicasa del Síndrome de Werner/deficienciaRESUMEN
A typo in the 'Reviewer information' section of this Letter was corrected online.
RESUMEN
This Letter is being retracted owing to issues with Fig. 1d and Supplementary Fig. 31b, and the unavailability of original data for these figures that raise concerns regarding the integrity of the figures. Nature published two previous corrections related to this Letter1,2. These issues in aggregate undermine the confidence in the integrity of this study. Authors Michael Foley, Monica Schenone, Nicola J. Tolliday, Todd R. Golub, Steven A. Carr, Alykhan F. Shamji, Andrew M. Stern and Stuart L. Schreiber agree with the Retraction. Authors Lakshmi Raj, Takao Ide, Aditi U. Gurkar, Anna Mandinova and Sam W. Lee disagree with the Retraction. Author Xiaoyu Li did not respond.
RESUMEN
The human genome contains thousands of long non-coding RNAs1, but specific biological functions and biochemical mechanisms have been discovered for only about a dozen2-7. A specific long non-coding RNA-non-coding RNA activated by DNA damage (NORAD)-has recently been shown to be required for maintaining genomic stability8, but its molecular mechanism is unknown. Here we combine RNA antisense purification and quantitative mass spectrometry to identify proteins that directly interact with NORAD in living cells. We show that NORAD interacts with proteins involved in DNA replication and repair in steady-state cells and localizes to the nucleus upon stimulation with replication stress or DNA damage. In particular, NORAD interacts with RBMX, a component of the DNA-damage response, and contains the strongest RBMX-binding site in the transcriptome. We demonstrate that NORAD controls the ability of RBMX to assemble a ribonucleoprotein complex-which we term NORAD-activated ribonucleoprotein complex 1 (NARC1)-that contains the known suppressors of genomic instability topoisomerase I (TOP1), ALYREF and the PRPF19-CDC5L complex. Cells depleted for NORAD or RBMX display an increased frequency of chromosome segregation defects, reduced replication-fork velocity and altered cell-cycle progression-which represent phenotypes that are mechanistically linked to TOP1 and PRPF19-CDC5L function. Expression of NORAD in trans can rescue defects caused by NORAD depletion, but rescue is significantly impaired when the RBMX-binding site in NORAD is deleted. Our results demonstrate that the interaction between NORAD and RBMX is important for NORAD function, and that NORAD is required for the assembly of the previously unknown topoisomerase complex NARC1, which contributes to maintaining genomic stability. In addition, we uncover a previously unknown function for long non-coding RNAs in modulating the ability of an RNA-binding protein to assemble a higher-order ribonucleoprotein complex.
Asunto(s)
ADN-Topoisomerasas de Tipo I/metabolismo , Inestabilidad Genómica , Complejos Multiproteicos/química , Complejos Multiproteicos/metabolismo , ARN Largo no Codificante/metabolismo , Proteínas de Unión al ARN/metabolismo , Sitios de Unión , Ciclo Celular , Proteínas de Ciclo Celular/metabolismo , Núcleo Celular/metabolismo , Supervivencia Celular , Segregación Cromosómica , Daño del ADN , Reparación del ADN , Enzimas Reparadoras del ADN/metabolismo , Replicación del ADN , Ribonucleoproteínas Nucleares Heterogéneas/metabolismo , Humanos , Espectrometría de Masas , Proteínas Nucleares/metabolismo , Unión Proteica , Factores de Empalme de ARN/metabolismo , ARN Largo no Codificante/genética , Ribonucleoproteínas/metabolismo , Factores de Transcripción/metabolismoRESUMEN
Casitas B-lineage lymphoma (CBL) encodes an E3 ubiquitin ligase and signaling adaptor that regulates receptor and nonreceptor tyrosine kinases. Recurrent CBL mutations occur in myeloid neoplasms, including 10% to 20% of chronic myelomonocytic leukemia (CMML) cases, and selectively disrupt the protein's E3 ubiquitin ligase activity. CBL mutations have been associated with poor prognosis, but the oncogenic mechanisms and therapeutic implications of CBL mutations remain incompletely understood. We combined functional assays and global mass spectrometry to define the phosphoproteome, CBL interactome, and mechanism of signaling activation in a panel of cell lines expressing an allelic series of CBL mutations. Our analyses revealed that increased LYN activation and interaction with mutant CBL are key drivers of enhanced CBL phosphorylation, phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) recruitment, and downstream phosphatidylinositol 3-kinase (PI3K)/AKT signaling in CBL-mutant cells. Signaling adaptor domains of CBL, including the tyrosine kinase-binding domain, proline-rich region, and C-terminal phosphotyrosine sites, were all required for the oncogenic function of CBL mutants. Genetic ablation or dasatinib-mediated inhibition of LYN reduced CBL phosphorylation, CBL-PIK3R1 interaction, and PI3K/AKT signaling. Furthermore, we demonstrated in vitro and in vivo antiproliferative efficacy of dasatinib in CBL-mutant cell lines and primary CMML. Overall, these mechanistic insights into the molecular function of CBL mutations provide rationale to explore the therapeutic potential of LYN inhibition in CBL-mutant myeloid malignancies.
Asunto(s)
Fosfatidilinositol 3-Quinasa Clase Ia/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-cbl/genética , Familia-src Quinasas/metabolismo , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/metabolismo , Humanos , Mutación , Mapas de Interacción de Proteínas , Proteínas Proto-Oncogénicas c-cbl/metabolismo , Transducción de SeñalRESUMEN
Deubiquitinases (DUBs) are a family of >100 proteases that hydrolyze isopeptide bonds linking ubiquitin to protein substrates, often leading to reduced substrate degradation through the ubiquitin proteasome system. Deregulation of DUB activity has been implicated in many diseases, including cancer, neurodegeneration and auto-inflammation, and several have been recognized as attractive targets for therapeutic intervention. Ubiquitin-derived covalent activity-based probes (ABPs) provide a powerful tool for DUB activity profiling, but their large recognition element impedes cellular permeability and presents an unmet need for small molecule ABPs which can account for regulation of DUB activity in intact cells or organisms. Here, through comprehensive chemoproteomic warhead profiling, we identify cyanopyrrolidine (CNPy) probe IMP-2373 (12) as a small molecule pan-DUB ABP to monitor DUB activity in physiologically relevant live cells. Through proteomics and targeted assays, we demonstrate that IMP-2373 quantitatively engages more than 35â DUBs across a range of non-toxic concentrations in diverse cell lines. We further demonstrate its application to quantification of changes in intracellular DUB activity during pharmacological inhibition and during MYC deregulation in a model of B cell lymphoma. IMP-2373 thus offers a complementary tool to ubiquitin ABPs to monitor dynamic DUB activity in the context of disease-relevant phenotypes.
Asunto(s)
Bioensayo , Complejo de la Endopetidasa Proteasomal , Citoplasma , Ubiquitina , Enzimas DesubicuitinizantesRESUMEN
Population genetic studies highlight a missense variant (G398S) of A1CF that is strongly associated with higher levels of blood triglycerides (TGs) and total cholesterol (TC). Functional analyses suggest that the mutation accelerates the secretion of very low-density lipoprotein (VLDL) from the liver by an unknown mechanism. Here, we used multiomics approaches to interrogate the functional difference between the WT and mutant A1CF. Using metabolomics analyses, we captured the cellular lipid metabolite changes induced by transient expression of the proteins, confirming that the mutant A1CF is able to relieve the TG accumulation induced by WT A1CF. Using a proteomics approach, we obtained the interactomic data of WT and mutant A1CF. Networking analyses show that WT A1CF interacts with three functional protein groups, RNA/mRNA processing, cytosolic translation, and, surprisingly, mitochondrial translation. The mutation diminishes these interactions, especially with the group of mitochondrial translation. Differential analyses show that the WT A1CF-interacting proteins most significantly different from the mutant are those for mitochondrial translation, whereas the most significant interacting proteins with the mutant are those for cytoskeleton and vesicle-mediated transport. RNA-seq analyses validate that the mutant, but not the WT, A1CF increases the expression of the genes responsible for cellular transport processes. On the contrary, WT A1CF affected the expression of mitochondrial matrix proteins and increased cell oxygen consumption. Thus, our studies confirm the previous hypothesis that A1CF plays broader roles in regulating gene expression. The interactions of the mutant A1CF with the vesicle-mediated transport machinery provide mechanistic insight in understanding the increased VLDL secretion in the A1CF mutation carriers.
Asunto(s)
Metabolismo de los Lípidos , Proteínas de Unión al ARN , Metabolismo de los Lípidos/genética , Hígado/metabolismo , Edición de ARN , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismoRESUMEN
Primordial germ cells (PGCs) form during early embryogenesis with a supply of maternal mRNAs that contain shorter poly(A) tails. How translation of maternal mRNAs is regulated during PGC development remains elusive. Here we describe a small-molecule screen with zebrafish embryos that identified primordazine, a compound that selectively ablates PGCs. Primordazine's effect on PGCs arises from translation repression through primordazine-response elements in the 3' UTRs. Systematic dissection of primordazine's mechanism of action revealed that translation of mRNAs during early embryogenesis occurs by two distinct pathways, depending on the length of their poly(A) tails. In addition to poly(A)-tail-dependent translation (PAT), early embryos perform poly(A)-tail-independent noncanonical translation (PAINT) via deadenylated 3' UTRs. Primordazine inhibits PAINT without inhibiting PAT, an effect that was also observed in quiescent, but not proliferating, mammalian cells. These studies reveal that PAINT is an alternative form of translation in the early embryo and is indispensable for PGC maintenance.
Asunto(s)
Regiones no Traducidas 3'/genética , Células Germinativas/metabolismo , Iniciación de la Cadena Peptídica Traduccional/genética , Animales , Línea Celular Tumoral , Hidrazinas/farmacología , Ratones , Iniciación de la Cadena Peptídica Traduccional/efectos de los fármacos , Pez CebraRESUMEN
Dysregulated oncogenic serine/threonine kinases play a pathological role in diverse forms of malignancies, including multiple myeloma (MM), and thus represent potential therapeutic targets. Here, we evaluated the biological and functional role of p21-activated kinase 4 (PAK4) and its potential as a new target in MM for clinical applications. PAK4 promoted MM cell growth and survival via activation of MM survival signaling pathways, including the MEK-extracellular signal-regulated kinase pathway. Furthermore, treatment with orally bioavailable PAK4 allosteric modulator (KPT-9274) significantly impacted MM cell growth and survival in a large panel of MM cell lines and primary MM cells alone and in the presence of bone marrow microenvironment. Intriguingly, we have identified FGFR3 as a novel binding partner of PAK4 and observed significant activity of KPT-9274 against t(4;14)-positive MM cells. This set of data supports PAK4 as an oncogene in myeloma and provide the rationale for the clinical evaluation of PAK4 modulator in myeloma.
Asunto(s)
Regulación Neoplásica de la Expresión Génica , Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/genética , Inhibidores de Proteínas Quinasas/farmacología , Receptor Tipo 3 de Factor de Crecimiento de Fibroblastos/genética , Quinasas p21 Activadas/genética , Regulación Alostérica , Animales , Apoptosis/efectos de los fármacos , Células de la Médula Ósea/efectos de los fármacos , Células de la Médula Ósea/enzimología , Células de la Médula Ósea/patología , Caspasas/genética , Caspasas/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Cromosomas Humanos Par 14 , Cromosomas Humanos Par 4 , Humanos , Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/enzimología , Leucocitos Mononucleares/patología , Ratones , Ratones Desnudos , Terapia Molecular Dirigida , Mieloma Múltiple/enzimología , Mieloma Múltiple/patología , Cultivo Primario de Células , Unión Proteica , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Receptor Tipo 3 de Factor de Crecimiento de Fibroblastos/metabolismo , Transducción de Señal , Translocación Genética , Ensayos Antitumor por Modelo de Xenoinjerto , Quinasas p21 Activadas/antagonistas & inhibidores , Quinasas p21 Activadas/metabolismoRESUMEN
High cancer death rates indicate the need for new anticancer therapeutic agents. Approaches to discovering new cancer drugs include target-based drug discovery and phenotypic screening. Here, we identified phosphodiesterase 3A modulators as cell-selective cancer cytotoxic compounds through phenotypic compound library screening and target deconvolution by predictive chemogenomics. We found that sensitivity to 6-(4-(diethylamino)-3-nitrophenyl)-5-methyl-4,5-dihydropyridazin-3(2H)-one, or DNMDP, across 766 cancer cell lines correlates with expression of the gene PDE3A, encoding phosphodiesterase 3A. Like DNMDP, a subset of known PDE3A inhibitors kill selected cancer cells, whereas others do not. Furthermore, PDE3A depletion leads to DNMDP resistance. We demonstrated that DNMDP binding to PDE3A promotes an interaction between PDE3A and Schlafen 12 (SLFN12), suggestive of a neomorphic activity. Coexpression of SLFN12 with PDE3A correlates with DNMDP sensitivity, whereas depletion of SLFN12 results in decreased DNMDP sensitivity. Our results implicate PDE3A modulators as candidate cancer therapeutic agents and demonstrate the power of predictive chemogenomics in small-molecule discovery.
Asunto(s)
Fosfodiesterasas de Nucleótidos Cíclicos Tipo 3/metabolismo , Citotoxinas/farmacología , Neoplasias/terapia , Piridazinas/química , Piridazinas/farmacología , Línea Celular , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Citotoxinas/química , Citotoxinas/aislamiento & purificación , Sistemas de Liberación de Medicamentos , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Genómica , Humanos , ImmunoblottingRESUMEN
Malignant transformation, driven by gain-of-function mutations in oncogenes and loss-of-function mutations in tumour suppressor genes, results in cell deregulation that is frequently associated with enhanced cellular stress (for example, oxidative, replicative, metabolic and proteotoxic stress, and DNA damage). Adaptation to this stress phenotype is required for cancer cells to survive, and consequently cancer cells may become dependent upon non-oncogenes that do not ordinarily perform such a vital function in normal cells. Thus, targeting these non-oncogene dependencies in the context of a transformed genotype may result in a synthetic lethal interaction and the selective death of cancer cells. Here we used a cell-based small-molecule screening and quantitative proteomics approach that resulted in the unbiased identification of a small molecule that selectively kills cancer cells but not normal cells. Piperlongumine increases the level of reactive oxygen species (ROS) and apoptotic cell death in both cancer cells and normal cells engineered to have a cancer genotype, irrespective of p53 status, but it has little effect on either rapidly or slowly dividing primary normal cells. Significant antitumour effects are observed in piperlongumine-treated mouse xenograft tumour models, with no apparent toxicity in normal mice. Moreover, piperlongumine potently inhibits the growth of spontaneously formed malignant breast tumours and their associated metastases in mice. Our results demonstrate the ability of a small molecule to induce apoptosis selectively in cells that have a cancer genotype, by targeting a non-oncogene co-dependency acquired through the expression of the cancer genotype in response to transformation-induced oxidative stress.
Asunto(s)
Apoptosis/efectos de los fármacos , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Dioxolanos/farmacología , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Animales , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Línea Celular , Línea Celular Tumoral , Transformación Celular Neoplásica , Ensayo Cometa , Daño del ADN/efectos de los fármacos , Dioxolanos/efectos adversos , Dioxolanos/química , Genotipo , Ratones , Metástasis de la Neoplasia/tratamiento farmacológico , Metástasis de la Neoplasia/patología , Bibliotecas de Moléculas Pequeñas/química , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Phenotypic cell-based screening is a powerful approach to small-molecule discovery, but a major challenge of this strategy lies in determining the intracellular target and mechanism of action (MoA) for validated hits. Here, we show that the small-molecule BRD0476, a novel suppressor of pancreatic ß-cell apoptosis, inhibits interferon-gamma (IFN-γ)-induced Janus kinase 2 (JAK2) and signal transducer and activation of transcription 1 (STAT1) signaling to promote ß-cell survival. However, unlike common JAK-STAT pathway inhibitors, BRD0476 inhibits JAK-STAT signaling without suppressing the kinase activity of any JAK. Rather, we identified the deubiquitinase ubiquitin-specific peptidase 9X (USP9X) as an intracellular target, using a quantitative proteomic analysis in rat ß cells. RNAi-mediated and CRISPR/Cas9 knockdown mimicked the effects of BRD0476, and reverse chemical genetics using a known inhibitor of USP9X blocked JAK-STAT signaling without suppressing JAK activity. Site-directed mutagenesis of a putative ubiquitination site on JAK2 mitigated BRD0476 activity, suggesting a competition between phosphorylation and ubiquitination to explain small-molecule MoA. These results demonstrate that phenotypic screening, followed by comprehensive MoA efforts, can provide novel mechanistic insights into ostensibly well-understood cell signaling pathways. Furthermore, these results uncover USP9X as a potential target for regulating JAK2 activity in cellular inflammation.
Asunto(s)
Células Secretoras de Insulina/efectos de los fármacos , Interferón gamma/inmunología , Janus Quinasa 2/inmunología , Sustancias Protectoras/química , Sustancias Protectoras/farmacología , Factor de Transcripción STAT1/inmunología , Animales , Apoptosis/efectos de los fármacos , Línea Celular , Supervivencia Celular/efectos de los fármacos , Humanos , Células Secretoras de Insulina/citología , Células Secretoras de Insulina/inmunología , Fosforilación/efectos de los fármacos , Ratas , Transducción de Señal/efectos de los fármacos , Ubiquitina Tiolesterasa/inmunología , Ubiquitinación/efectos de los fármacosRESUMEN
Target-identification and mechanism-of-action studies have important roles in small-molecule probe and drug discovery. Biological and technological advances have resulted in the increasing use of cell-based assays to discover new biologically active small molecules. Such studies allow small-molecule action to be tested in a more disease-relevant setting at the outset, but they require follow-up studies to determine the precise protein target or targets responsible for the observed phenotype. Target identification can be approached by direct biochemical methods, genetic interactions or computational inference. In many cases, however, combinations of approaches may be required to fully characterize on-target and off-target effects and to understand mechanisms of small-molecule action.
Asunto(s)
Biomarcadores Farmacológicos/metabolismo , Descubrimiento de Drogas , Evaluación Preclínica de Medicamentos , Ensayos Analíticos de Alto Rendimiento , Bibliotecas de Moléculas Pequeñas/metabolismo , Animales , Biomarcadores Farmacológicos/química , Humanos , Marcaje Isotópico , Espectrometría de Masas , Terapia Molecular Dirigida , Fenotipo , Interferencia de ARN , Genética Inversa , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/farmacología , Estudios de Validación como AsuntoRESUMEN
Population-based association studies have identified many genetic risk loci for coronary artery disease (CAD), but it is often unclear how genes within these loci are linked to CAD. Here, we perform interaction proteomics for 11 CAD-risk genes to map their protein-protein interactions (PPIs) in human vascular cells and elucidate their roles in CAD. The resulting PPI networks contain interactions that are outside of known biology in the vasculature and are enriched for genes involved in immunity-related and arterial-wall-specific mechanisms. Several PPI networks derived from smooth muscle cells are significantly enriched for genetic variants associated with CAD and related vascular phenotypes. Furthermore, the networks identify 61 genes that are found in genetic loci associated with risk of CAD, prioritizing them as the causal candidates within these loci. These findings indicate that the PPI networks we have generated are a rich resource for guiding future research into the molecular pathogenesis of CAD.