RESUMEN
Histones are highly posttranslationally modified proteins that regulate gene expression by modulating chromatin structure and function. Acetylation and methylation are the most abundant histone modifications, with methylation occurring on lysine (mono-, di-, and trimethylation) and arginine (mono- and dimethylation) predominately on histones H3 and H4. In addition, arginine dimethylation can occur either symmetrically (SDMA) or asymmetrically (ADMA) conferring different biological functions. Despite the importance of histone methylation on gene regulation, characterization and quantitation of this modification have proven to be quite challenging. Great advances have been made in the analysis of histone modification using both bottom-up and top-down mass spectrometry (MS). However, MS-based analysis of histone posttranslational modifications (PTMs) is still problematic, due both to the basic nature of the histone N-terminal tails and to the combinatorial complexity of the histone PTMs. In this report, we describe a simplified MS-based platform for histone methylation analysis. The strategy uses chemical acetylation with d0-acetic anhydride to collapse all the differently acetylated histone forms into one form, greatly reducing the complexity of the peptide mixture and improving sensitivity for the detection of methylation via summation of all the differently acetylated forms. We have used this strategy for the robust identification and relative quantitation of H4R3 methylation, for which stoichiometry and symmetry status were determined, providing an antibody-independent evidence that H4R3 is a substrate for both Type I and Type II PRMTs. Additionally, this approach permitted the robust detection of H4K5 monomethylation, a very low stoichiometry methylation event (0.02% methylation). In an independent example, we developed an in vitro assay to profile H3K27 methylation and applied it to an EZH2 mutant xenograft model following small-molecule inhibition of the EZH2 methyltransferase. These specific examples highlight the utility of this simplified MS-based approach to quantify histone methylation profiles.
Asunto(s)
Histonas/metabolismo , Acetilación , Línea Celular Tumoral , Proteína Potenciadora del Homólogo Zeste 2/genética , Proteína Potenciadora del Homólogo Zeste 2/metabolismo , Humanos , Espectrometría de Masas , MetilaciónRESUMEN
IQ motif-containing GTPase-activating protein 1 (IQGAP1) is a scaffold protein that interacts with numerous binding partners and thereby regulates fundamental biological processes. The functions of IQGAP1 are modulated by several mechanisms, including protein binding, self-association, subcellular localization, and phosphorylation. Proteome-wide screens have indicated that IQGAP1 is ubiquitinated, but the possible effects of this post-translational modification on its function are unknown. Here we characterized and evaluated the function of IQGAP1 ubiquitination. Using MS-based analysis in HEK293 cells, we identified six lysine residues (Lys-556, -1155, -1230, -1465, -1475, and -1528) as ubiquitination sites in IQGAP1. To elucidate the biological consequences of IQGAP1 ubiquitination, we converted each of these lysines to arginine and found that replacing two of these residues, Lys-1155 and Lys-1230, in the GAP-related domain of IQGAP1 (termed IQGAP1 GRD-2K) reduces its ubiquitination. Moreover, IQGAP1 GRD-2K bound a significantly greater proportion of the two Rho GTPases cell division cycle 42 (CDC42) and Rac family small GTPase 1 (RAC1) than did WT IQGAP1. Consistent with this observation, reconstitution of IQGAP1-null cells with IQGAP1 GRD-2K significantly increased the amount of active CDC42 and enhanced cell migration significantly more than WT IQGAP1. Our results reveal that ubiquitination of the CDC42 regulator IQGAP1 alters its ability to bind to and activate this GTPase, leading to physiological effects. Collectively, these findings expand our view of the role of ubiquitination in cell signaling and provide additional insight into CDC42 regulation.
Asunto(s)
Arginina/metabolismo , Lisina/metabolismo , Ubiquitina/metabolismo , Ubiquitinación , Proteína de Unión al GTP cdc42/metabolismo , Proteína de Unión al GTP rac1/metabolismo , Proteínas Activadoras de ras GTPasa/metabolismo , Arginina/química , Arginina/genética , Movimiento Celular , Células HEK293 , Humanos , Lisina/química , Lisina/genética , Proteína de Unión al GTP cdc42/genética , Proteína de Unión al GTP rac1/genética , Proteínas Activadoras de ras GTPasa/química , Proteínas Activadoras de ras GTPasa/genéticaRESUMEN
IN BRIEF In this article, the authors discuss several innovative concepts UnitedHealth Group Research & Development is exploring to help patients manage their type 2 diabetes. The article focuses on efforts to use remote support programs and wearable technology to empower patients to take more active roles in managing their health and to foster more interactive patient-provider conversations. Additionally, the authors reflect on how such efforts could particularly benefit medically underserved communities. They offer observations from claims data about current health outcomes and costs in underserved areas.
RESUMEN
Microsatellite-unstable (MSI) cancers require WRN helicase to resolve replication stress due to expanded DNA (TA)n dinucleotide repeats. WRN is a promising synthetic lethal target for MSI tumors, and WRN inhibitors are in development. In this study, we used CRISPR-Cas9 base editing to map WRN residues critical for MSI cells, validating the helicase domain as the primary drug target. Fragment-based screening led to the development of potent and highly selective WRN helicase covalent inhibitors. These compounds selectively suppressed MSI model growth in vitro and in vivo by mimicking WRN loss, inducing DNA double-strand breaks at expanded TA repeats and DNA damage. Assessment of biomarkers in preclinical models linked TA-repeat expansions and mismatch repair alterations to compound activity. Efficacy was confirmed in immunotherapy-resistant organoids and patient-derived xenograft models. The discovery of potent, selective covalent WRN inhibitors provides proof of concept for synthetic lethal targeting of WRN in MSI cancer and tools to dissect WRN biology. Significance: We report the discovery and characterization of potent, selective WRN helicase inhibitors for MSI cancer treatment, with biomarker analysis and evaluation of efficacy in vivo and in immunotherapy-refractory preclinical models. These findings pave the way to translate WRN inhibition into MSI cancer therapies and provide tools to investigate WRN biology. See related commentary by Wainberg, p. 1369.
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Helicasa del Síndrome de Werner , Humanos , Helicasa del Síndrome de Werner/genética , Ratones , Animales , Inestabilidad de Microsatélites , Neoplasias/tratamiento farmacológico , Neoplasias/genética , Neoplasias/patología , Línea Celular Tumoral , Ensayos Antitumor por Modelo de Xenoinjerto , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/uso terapéuticoRESUMEN
Sulfur(VI) fluorides (SFs) have emerged as valuable electrophiles for the design of "beyond-cysteine" covalent inhibitors and offer potential for expansion of the liganded proteome. Since SFs target a broad range of nucleophilic amino acids, they deliver an approach for the covalent modification of proteins without requirement for a proximal cysteine residue. Further to this, libraries of reactive fragments present an innovative approach for the discovery of ligands and tools for proteins of interest by leveraging a breadth of mass spectrometry analytical approaches. Herein, we report a screening approach that exploits the unique properties of SFs for this purpose. Libraries of SF-containing reactive fragments were synthesized, and a direct-to-biology workflow was taken to efficiently identify hit compounds for CAII and BCL6. The most promising hits were further characterized to establish the site(s) of covalent modification, modification kinetics, and target engagement in cells. Crystallography was used to gain a detailed molecular understanding of how these reactive fragments bind to their target. It is anticipated that this screening protocol can be used for the accelerated discovery of "beyond-cysteine" covalent inhibitors.
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Cisteína , Fluoruros , Cisteína/química , Ligandos , Aminoácidos , AzufreRESUMEN
Phospholipase C (PLC) enzymes are an important family of regulatory proteins involved in numerous cellular functions, primarily through hydrolysis of the polar head group from inositol-containing membrane phospholipids. U73122 (1-(6-((17ß-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione), one of only a few small molecules reported to inhibit the activity of these enzymes, has been broadly applied as a pharmacological tool to implicate PLCs in diverse experimental phenotypes. The purpose of this study was to develop a better understanding of molecular interactions between U73122 and PLCs. Hence, the effects of U73122 on human PLCß3 (hPLCß3) were evaluated in a cell-free micellar system. Surprisingly, U73122 increased the activity of hPLCß3 in a concentration- and time-dependent manner; up to an 8-fold increase in enzyme activity was observed with an EC50=13.6±5 µm. Activation of hPLCß3 by U73122 required covalent modification of cysteines as evidenced by the observation that enzyme activation was attenuated by thiol-containing nucleophiles, l-cysteine and glutathione. Mass spectrometric analysis confirmed covalent reaction with U73122 at eight cysteines, although maximum activation was achieved without complete alkylation; the modified residues were identified by LC/MS/MS peptide sequencing. Interestingly, U73122 (10 µm) also activated hPLCγ1 (>10-fold) and hPLCß2 (â¼2-fold); PLCδ1 was neither activated nor inhibited. Therefore, in contrast to its reported inhibitory potential, U73122 failed to inhibit several purified PLCs. Most of these PLCs were directly activated by U73122, and a simple mechanism for the activation is proposed. These results strongly suggest a need to re-evaluate the use of U73122 as a general inhibitor of PLC isozymes.
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Estrenos/farmacología , Inhibidores de Fosfodiesterasa/farmacología , Pirrolidinonas/farmacología , Fosfolipasas de Tipo C/metabolismo , Secuencia de Aminoácidos , Activación Enzimática/efectos de los fármacos , Estrenos/química , Humanos , Datos de Secuencia Molecular , Inhibidores de Fosfodiesterasa/química , Pirrolidinonas/química , Fosfolipasas de Tipo C/químicaRESUMEN
Analysis of the x-ray crystal structure of mono-substituted acetylenic thienopyrimidine 6 complexed with the ErbB family enzyme ErbB-4 revealed a covalent bond between the terminal carbon of the acetylene moiety and the sulfhydryl group of Cys-803 at the solvent interface. The identification of this covalent adduct suggested that acetylenic thienopyrimidine 6 and related analogs might also be capable of forming an analogous covalent adduct with EGFR, which has a conserved cysteine (797) near the ATP binding pocket. To test this hypothesis, we treated a truncated, catalytically competent form of EGFR (678-1020) with a structurally related propargylic amine (8). An investigation of the resulting complex by mass spectrometry revealed the formation of a covalent complex of thienopyrimidine 8 with Cys-797 of EGFR. This finding enabled us to readily assess the irreversibility of various inhibitors and also facilitated a structure-activity relationship understanding of the covalent modifying potential and biological activity of a series of acetylenic thienopyrimidine compounds with potent antitumor activity. Several ErbB family enzyme and cell potent 6-ethynyl thienopyrimidine kinase inhibitors were found to form covalent adducts with EGFR.
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Alquinos/metabolismo , Compuestos de Anilina/metabolismo , Receptores ErbB/metabolismo , Modelos Moleculares , Pirimidinas/metabolismo , Animales , Proliferación Celular/efectos de los fármacos , Cristalografía por Rayos X , Relación Dosis-Respuesta a Droga , Femenino , Isatina/análogos & derivados , Isatina/metabolismo , Espectrometría de Masas , Ratones , Ratones SCID , Estructura Molecular , Pirimidinas/toxicidad , Proteínas Tirosina Quinasas Receptoras/metabolismo , Relación Estructura-Actividad , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Arginine methylation has been recognized as a post-translational modification with pleiotropic effects that span from regulation of transcription to metabolic processes that contribute to aberrant cell proliferation and tumorigenesis. This has brought significant attention to the development of therapeutic strategies aimed at blocking the activity of protein arginine methyltransferases (PRMTs), which catalyze the formation of various methylated arginine products on a wide variety of cellular substrates. GSK3368715 is a small molecule inhibitor of type I PRMTs currently in clinical development. Here, we evaluate the effect of type I PRMT inhibition on arginine methylation in normal human peripheral blood mononuclear cells and utilize a broad proteomic approach to identify type I PRMT substrates. This work identified heterogenous nuclear ribonucleoprotein A1 (hnRNP-A1) as a pharmacodynamic biomarker of type I PRMT inhibition. Utilizing targeted mass spectrometry (MS), methods were developed to detect and quantitate changes in methylation of specific arginine residues on hnRNP-A1. This resulted in the development and validation of novel MS and immune assays useful for the assessment of GSK3368715 induced pharmacodynamic effects in blood and tumors that can be applied to GSK3368715 clinical trials.
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Antineoplásicos/farmacocinética , Biomarcadores , Ribonucleoproteína Nuclear Heterogénea A1/metabolismo , Proteína-Arginina N-Metiltransferasas/antagonistas & inhibidores , Proteínas Represoras/antagonistas & inhibidores , Animales , Antineoplásicos/uso terapéutico , Antineoplásicos Inmunológicos/química , Antineoplásicos Inmunológicos/farmacocinética , Antineoplásicos Inmunológicos/farmacología , Arginina/metabolismo , Células Cultivadas , Cromatografía Liquida , Monitoreo de Drogas , Activación Enzimática , Inhibidores Enzimáticos/farmacocinética , Inhibidores Enzimáticos/uso terapéutico , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Ribonucleoproteína Nuclear Heterogénea A1/sangre , Humanos , Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/metabolismo , Espectrometría de Masas , Metilación , Ratones , Terapia Molecular Dirigida , Neoplasias/sangre , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Proteína-Arginina N-Metiltransferasas/genética , Proteínas Represoras/genética , Especificidad por SustratoRESUMEN
Characterization of recombinant protein purification fractions and final products by liquid chromatography-mass spectrometry (LC/MS) are requested more frequently each year. A protein open-access (OA) LC/MS system was developed in our laboratory to meet this demand. This paper compares the system that we originally implemented in our facilities in 2003 to the one now in use, and discusses, in more detail, recent enhancements that have improved its robustness, reliability, and data reporting capabilities. The system utilizes instruments equipped with reversed-phase chromatography and an orthogonal accelerated time-of-flight mass spectrometer fitted with an electrospray source. Sample analysis requests are accomplished using a simple form on a web-enabled laboratory information management system (LIMS). This distributed form is accessible from any intranet-connected company desktop computer. Automated data acquisition and processing are performed using a combination of in-house (OA-Self Service, OA-Monitor, and OA-Analysis Engine) and vendor-supplied programs (AutoLynx, and OpenLynx) located on acquisition computers and off-line processing workstations. Analysis results are then reported via the same web-based LIMS. Also presented are solutions to problems not addressed on commercially available, small-molecule OA-LC/MS systems. These include automated transforming of mass-to-charge (m/z) spectra to mass spectra and automated data interpretation that considers minor variants to the protein sequence-such as common post-translational modifications (PTMs). Currently, our protein OA-LC/MS platform runs on five LC/MS instruments located in three separate GlaxoSmithKline R&D sites in the US and UK. To date, more than 8000 protein OA-LC/MS samples have been analyzed. With these user friendly and highly automated OA systems in place, mass spectrometry plays a key role in assessing the quality of recombinant proteins, either produced at our facilities or bought from external sources, without dedicating extensive amounts of analyst resource.
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Anhidrasas Carbónicas/química , Caseínas/química , Procesamiento Automatizado de Datos , Gestión de la Información , Espectrometría de Masa por Ionización de Electrospray/métodos , Animales , Bovinos , Cromatografía Líquida de Alta Presión , Mapeo Peptídico , Proteínas Recombinantes/química , Reproducibilidad de los Resultados , Espectrometría de Masa por Ionización de Electrospray/instrumentaciónRESUMEN
4-Chloro-N-(2-{[5-trifluoromethyl)-2-pyridyl]sulfonyl}ethyl)benzamide 3 (GSK3787) was identified as a potent and selective ligand for PPARdelta with good pharmacokinetic properties. A detailed binding study using mass spectral analysis confirmed covalent binding to Cys249 within the PPARdelta binding pocket. Gene expression studies showed that pyridylsulfone 3 antagonized the transcriptional activity of PPARdelta and inhibited basal CPT1a gene transcription. Compound 3 is a PPARdelta antagonist with utility as a tool to elucidate PPARdelta cell biology and pharmacology.
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Benzamidas/síntesis química , PPAR delta/antagonistas & inhibidores , Sulfonas/síntesis química , Animales , Antineoplásicos/síntesis química , Antineoplásicos/farmacocinética , Antineoplásicos/farmacología , Benzamidas/farmacocinética , Benzamidas/farmacología , Sitios de Unión , Carnitina O-Palmitoiltransferasa/biosíntesis , Carnitina O-Palmitoiltransferasa/genética , Línea Celular Tumoral , Cisteína/metabolismo , Ensayos de Selección de Medicamentos Antitumorales , Genes Reporteros , Humanos , Ligandos , Masculino , Espectrometría de Masas , Ratones , Ratones Endogámicos C57BL , Fibras Musculares Esqueléticas/efectos de los fármacos , Fibras Musculares Esqueléticas/enzimología , PPAR delta/agonistas , PPAR delta/genética , Proteínas Serina-Treonina Quinasas/biosíntesis , Proteínas Serina-Treonina Quinasas/genética , Piruvato Deshidrogenasa Quinasa Acetil-Transferidora , Relación Estructura-Actividad , Sulfonas/farmacocinética , Sulfonas/farmacología , Distribución Tisular , Transcripción Genética/efectos de los fármacosRESUMEN
Each year increasing numbers of proteins are submitted for routine characterization by liquid chromatography/mass spectrometry (LC/MS). This paper reports a solution that transforms routine LC/MS analysis of proteins into a fully automated process that significantly reduces analyst intervention. The solution developed, protein open-access (OA) LC/MS, consists of web-enabled sample submission and registration, automated data processing, data interpretation, and report generation. Sample submissions and results are recorded in a LIMS that utilizes an Oracle database. The protein sequence is captured during the sample submission process, stored in the database, and utilized to determine the theoretical protein molecular weight. This calculated mass is used to set the parameters for transformation of the mass-to-charge spectra to the mass domain and evaluate the presence or absence of the desired protein. Three protein OA-LC/MS instruments have been deployed in our facility to support protein characterization, purification, and modification efforts.