RESUMEN
Transfer RNA (tRNA) modifications are crucial for protein synthesis, but their position-specific physiological roles remain poorly understood. Here we investigate the impact of N4-acetylcytidine (ac4C), a highly conserved tRNA modification, using a Thumpd1 knockout mouse model. We find that loss of Thumpd1-dependent tRNA acetylation leads to reduced levels of tRNALeu, increased ribosome stalling, and activation of eIF2α phosphorylation. Thumpd1 knockout mice exhibit growth defects and sterility. Remarkably, concurrent knockout of Thumpd1 and the stress-sensing kinase Gcn2 causes penetrant postnatal lethality, indicating a critical genetic interaction. Our findings demonstrate that a modification restricted to a single position within type II cytosolic tRNAs can regulate ribosome-mediated stress signaling in mammalian organisms, with implications for our understanding of translation control as well as therapeutic interventions.
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Multiple myeloma (MM) is an incurable plasma cell malignancy that exploits transcriptional networks driven by IRF4. We employ a multi-omics approach to discover IRF4 vulnerabilities, integrating functional genomics screening, spatial proteomics, and global chromatin mapping. ARID1A, a member of the SWI/SNF chromatin remodeling complex, is required for IRF4 expression and functionally associates with IRF4 protein on chromatin. Deleting Arid1a in activated murine B cells disrupts IRF4-dependent transcriptional networks and blocks plasma cell differentiation. Targeting SWI/SNF activity leads to rapid loss of IRF4-target gene expression and quenches global amplification of oncogenic gene expression by MYC, resulting in profound toxicity to MM cells. Notably, MM patients with aggressive disease bear the signature of SWI/SNF activity, and SMARCA2/4 inhibitors remain effective in immunomodulatory drug (IMiD)-resistant MM cells. Moreover, combinations of SWI/SNF and MEK inhibitors demonstrate synergistic toxicity to MM cells, providing a promising strategy for relapsed/refractory disease.
Asunto(s)
Proteínas de Unión al ADN , Factores Reguladores del Interferón , Mieloma Múltiple , Células Plasmáticas , Factores de Transcripción , Mieloma Múltiple/tratamiento farmacológico , Mieloma Múltiple/patología , Mieloma Múltiple/genética , Mieloma Múltiple/metabolismo , Factores Reguladores del Interferón/metabolismo , Factores Reguladores del Interferón/genética , Animales , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Humanos , Ratones , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/genética , Células Plasmáticas/efectos de los fármacos , Células Plasmáticas/metabolismo , Células Plasmáticas/patología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Línea Celular Tumoral , Diferenciación Celular/efectos de los fármacosRESUMEN
The tumor microenvironment consists of resident tumor cells organized within a compositionally diverse, three-dimensional (3D) extracellular matrix (ECM) network that cannot be replicated in vitro using bottom-up synthesis. We report a new self-assembly system to engineer ECM-rich 3D MatriSpheres wherein tumor cells actively organize and concentrate microgram quantities of decellularized ECM dispersions which modulate cell phenotype. 3D colorectal cancer (CRC) MatriSpheres were created using decellularized small intestine submucosa (SIS) as an orthotopic ECM source that had greater proteomic homology to CRC tumor ECM than traditional ECM formulations such as Matrigel. SIS ECM was rapidly concentrated from its environment and assembled into ECM-rich 3D stroma-like regions by mouse and human CRC cell lines within 4-5 days via a mechanism that was rheologically distinct from bulk hydrogel formation. Both ECM organization and transcriptional regulation by 3D ECM cues affected programs of malignancy, lipid metabolism, and immunoregulation that corresponded with an in vivo MC38 tumor cell subpopulation identified via single cell RNA sequencing. This 3D modeling approach stimulates tumor specific tissue morphogenesis that incorporates the complexities of both cancer cell and ECM compartments in a scalable, spontaneous assembly process that may further facilitate precision medicine.
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Neuroblastoma RAS (NRAS) is an oncogene that is deregulated and highly mutated in cancers including melanomas and acute myeloid leukemias. The 5' untranslated region (UTR) (5' UTR) of the NRAS mRNA contains a G-quadruplex (G4) that regulates translation. Here we report a novel class of small molecule that binds to the G4 structure located in the 5' UTR of the NRAS mRNA. We used a small molecule microarray screen to identify molecules that selectively bind to the NRAS-G4 with submicromolar affinity. One compound inhibits the translation of NRAS in vitro but showed only moderate effects on the NRAS levels in cellulo. Rapid Amplification of cDNA Ends and RT-PCR analysis revealed that the predominant NRAS transcript does not possess the G4 structure. Thus, although NRAS transcripts lack a G4 in many cell lines the concept of targeting folded regions within 5' UTRs to control translation remains a highly attractive strategy.
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G-Cuádruplex , Neuroblastoma , Humanos , Regiones no Traducidas 5'/genética , ARN Mensajero/genética , Línea Celular , Proteínas de la Membrana/genética , GTP Fosfohidrolasas/genéticaRESUMEN
Most tumor cells undergo apoptosis in circulation and at the metastatic organ sites due to host immune surveillance and a hostile microenvironment. It remains to be elucidated whether dying tumor cells have a direct effect on live tumor cells during the metastatic process and what the underlying mechanisms are. Here we report that apoptotic cancer cells enhance the metastatic outgrowth of surviving cells through Padi4-mediated nuclear expulsion. Tumor cell nuclear expulsion results in an extracellular DNA-protein complex that is enriched with receptor for advanced glycation endproducts (RAGE) ligands. The chromatin-bound RAGE ligand S100a4 activates RAGE receptors in neighboring surviving tumor cells, leading to Erk activation. In addition, we identified nuclear expulsion products in human patients with breast, bladder and lung cancer and a nuclear expulsion signature correlated with poor prognosis. Collectively, our study demonstrates how apoptotic cell death can enhance the metastatic outgrowth of neighboring live tumor cells.
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Neoplasias Pulmonares , Proteína de Unión al Calcio S100A4 , Humanos , Apoptosis , Neoplasias Pulmonares/metabolismo , Receptor para Productos Finales de Glicación Avanzada/metabolismo , Proteína de Unión al Calcio S100A4/genética , Proteína de Unión al Calcio S100A4/metabolismo , Microambiente TumoralRESUMEN
Proteotoxicity from insufficient clearance of misfolded/damaged proteins underlies many diseases. Carboxyl terminus of Hsc70-interacting protein (CHIP) is an important regulator of proteostasis in many cells, having E3-ligase and chaperone functions and often directing damaged proteins towards proteasome recycling. While enhancing CHIP functionality has broad therapeutic potential, prior efforts have all relied on genetic upregulation. Here we report that CHIP-mediated protein turnover is markedly post-translationally enhanced by direct protein kinase G (PKG) phosphorylation at S20 (mouse, S19 human). This increases CHIP binding affinity to Hsc70, CHIP protein half-life, and consequent clearance of stress-induced ubiquitinated-insoluble proteins. PKG-mediated CHIP-pS20 or expressing CHIP-S20E (phosphomimetic) reduces ischemic proteo- and cytotoxicity, whereas a phospho-silenced CHIP-S20A amplifies both. In vivo, depressing PKG activity lowers CHIP-S20 phosphorylation and protein, exacerbating proteotoxicity and heart dysfunction after ischemic injury. CHIP-S20E knock-in mice better clear ubiquitinated proteins and are cardio-protected. PKG activation provides post-translational enhancement of protein quality control via CHIP.
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Proteínas Quinasas Dependientes de GMP Cíclico/metabolismo , Isquemia/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Secuencias de Aminoácidos , Animales , Proteínas Quinasas Dependientes de GMP Cíclico/genética , Femenino , Corazón/fisiopatología , Humanos , Isquemia/enzimología , Isquemia/genética , Isquemia/fisiopatología , Masculino , Ratones , Miocardio/metabolismo , Fosforilación , Ubiquitina-Proteína Ligasas/química , Ubiquitina-Proteína Ligasas/genéticaRESUMEN
Proteoforms containing post-translational modifications (PTMs) represent a degree of functional diversity only harnessed through analytically precise simultaneous quantification of multiple PTMs. Here we present a method to accurately differentiate an unmodified peptide from its PTM-containing counterpart through data-independent acquisition-mass spectrometry, leveraging small precursor mass windows to physically separate modified peptidoforms from each other during MS2 acquisition. We utilize a lysine and arginine PTM-enriched peptide assay library and site localization algorithm to simultaneously localize and quantify seven PTMs including mono-, di-, and trimethylation, acetylation, and succinylation in addition to total protein quantification in a single MS run without the need to enrich experimental samples. To evaluate biological relevance, this method was applied to liver lysate from differentially methylated nonalcoholic steatohepatitis (NASH) mouse models. We report that altered methylation and acetylation together with total protein changes drive the novel hypothesis of a regulatory function of PTMs in protein synthesis and mRNA stability in NASH.
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Hepatopatías , Lisina , Acetilación , Animales , Arginina , Lisina/metabolismo , Ratones , Procesamiento Proteico-Postraduccional , ProteómicaRESUMEN
Coronary artery disease remains a leading cause of death in industrialized nations, and early detection of disease is a critical intervention target to effectively treat patients and manage risk. Proteomic analysis of mixed tissue homogenates may obscure subtle protein changes that occur uniquely in underlying tissue subtypes. The unsupervised 'convex analysis of mixtures' (CAM) tool has previously been shown to effectively segregate cellular subtypes from mixed expression data. In this study, we hypothesized that CAM would identify proteomic information specifically informative to early atherosclerosis lesion involvement that could lead to potential markers of early disease detection. We quantified the proteome of 99 paired abdominal aorta (AA) and left anterior descending coronary artery (LAD) specimens (N = 198 specimens total) acquired during autopsy of young adults free of diagnosed cardiac disease. The CAM tool was then used to segregate protein subsets uniquely associated with different underlying tissue types, yielding markers of normal and fibrous plaque (FP) tissues in LAD and AA (N = 62 lesions markers). CAM-derived FP marker expression was validated against pathologist estimated luminal surface involvement of FP, as well as in an orthogonal cohort of "pure" fibrous plaque, fatty streak, and normal vascular specimens. A targeted mass spectrometry (MS) assay quantified 39 of 62 CAM-FP markers in plasma from women with angiographically verified coronary artery disease (CAD, N = 46) or free from apparent CAD (control, N = 40). Elastic net variable selection with logistic regression reduced this list to 10 proteins capable of classifying CAD status in this cohort with <6% misclassification error, and a mean area under the receiver operating characteristic curve of 0.992 (confidence interval 0.968-0.998) after cross validation. The proteomics-CAM workflow identified lesion-specific molecular biomarker candidates by distilling the most representative molecules from heterogeneous tissue types.
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Aterosclerosis , Enfermedad de la Arteria Coronaria , Aterosclerosis/diagnóstico , Biomarcadores , Enfermedad de la Arteria Coronaria/diagnóstico , Femenino , Humanos , Proteoma , Proteómica , Adulto JovenRESUMEN
Protein citrullination (or deimination), an irreversible post-translational modification, has been implicated in several physiological and pathological processes, including gene expression regulation, apoptosis, rheumatoid arthritis, and Alzheimer's disease. Several research studies have been carried out on citrullination under many conditions. However, until now, challenges in sample preparation and data analysis have made it difficult to confidently identify a citrullinated protein and assign the citrullinated site. To overcome these limitations, we generated a mouse hyper-citrullinated spectral library and set up coordinates to confidently identify and validate citrullinated sites. Using this workflow, we detect a four-fold increase in citrullinated proteome coverage across six mouse organs compared with the current state-of-the art techniques. Our data reveal that the subcellular distribution of citrullinated proteins is tissue-type-dependent and that citrullinated targets are involved in fundamental physiological processes, including the metabolic process. These data represent the first report of a hyper-citrullinated library for the mouse and serve as a central resource for exploring the role of citrullination in this organism.
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Citrulina/metabolismo , Redes y Vías Metabólicas/fisiología , Biblioteca de Péptidos , Péptidos/metabolismo , Procesamiento Proteico-Postraduccional , Secuencia de Aminoácidos , Animales , Encéfalo/metabolismo , Cromatografía Liquida , Biología Computacional/métodos , Riñón/química , Riñón/metabolismo , Hígado/química , Hígado/metabolismo , Pulmón/química , Pulmón/metabolismo , Masculino , Espectrometría de Masas , Ratones , Ratones Endogámicos C57BL , Muramidasa/química , Músculo Esquelético/química , Músculo Esquelético/metabolismo , Miocardio/química , Miocardio/metabolismo , Especificidad de Órganos , Péptidos/química , Desiminasas de la Arginina Proteica/químicaRESUMEN
The mechanistic target of rapamycin complex-1 (mTORC1) coordinates regulation of growth, metabolism, protein synthesis and autophagy1. Its hyperactivation contributes to disease in numerous organs, including the heart1,2, although broad inhibition of mTORC1 risks interference with its homeostatic roles. Tuberin (TSC2) is a GTPase-activating protein and prominent intrinsic regulator of mTORC1 that acts through modulation of RHEB (Ras homologue enriched in brain). TSC2 constitutively inhibits mTORC1; however, this activity is modified by phosphorylation from multiple signalling kinases that in turn inhibits (AMPK and GSK-3ß) or stimulates (AKT, ERK and RSK-1) mTORC1 activity3-9. Each kinase requires engagement of multiple serines, impeding analysis of their role in vivo. Here we show that phosphorylation or gain- or loss-of-function mutations at either of two adjacent serine residues in TSC2 (S1365 and S1366 in mice; S1364 and S1365 in humans) can bidirectionally control mTORC1 activity stimulated by growth factors or haemodynamic stress, and consequently modulate cell growth and autophagy. However, basal mTORC1 activity remains unchanged. In the heart, or in isolated cardiomyocytes or fibroblasts, protein kinase G1 (PKG1) phosphorylates these TSC2 sites. PKG1 is a primary effector of nitric oxide and natriuretic peptide signalling, and protects against heart disease10-13. Suppression of hypertrophy and stimulation of autophagy in cardiomyocytes by PKG1 requires TSC2 phosphorylation. Homozygous knock-in mice that express a phosphorylation-silencing mutation in TSC2 (TSC2(S1365A)) develop worse heart disease and have higher mortality after sustained pressure overload of the heart, owing to mTORC1 hyperactivity that cannot be rescued by PKG1 stimulation. However, cardiac disease is reduced and survival of heterozygote Tsc2S1365A knock-in mice subjected to the same stress is improved by PKG1 activation or expression of a phosphorylation-mimicking mutation (TSC2(S1365E)). Resting mTORC1 activity is not altered in either knock-in model. Therefore, TSC2 phosphorylation is both required and sufficient for PKG1-mediated cardiac protection against pressure overload. The serine residues identified here provide a genetic tool for bidirectional regulation of the amplitude of stress-stimulated mTORC1 activity.
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Proteínas Quinasas Dependientes de GMP Cíclico/metabolismo , Cardiopatías/prevención & control , Cardiopatías/fisiopatología , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Proteína 2 del Complejo de la Esclerosis Tuberosa/química , Proteína 2 del Complejo de la Esclerosis Tuberosa/metabolismo , Animales , Autofagia , Células Cultivadas , Progresión de la Enfermedad , Activación Enzimática , Everolimus/farmacología , Femenino , Técnicas de Sustitución del Gen , Células HEK293 , Cardiopatías/genética , Cardiopatías/patología , Humanos , Hipertrofia/tratamiento farmacológico , Hipertrofia/patología , Masculino , Diana Mecanicista del Complejo 1 de la Rapamicina/antagonistas & inhibidores , Ratones , Mutación , Miocitos Cardíacos/patología , Fosforilación , Fosfoserina/metabolismo , Presión , Ratas , Ratas Wistar , Serina/genética , Serina/metabolismo , Proteína 2 del Complejo de la Esclerosis Tuberosa/genéticaRESUMEN
Patients with diabetes are at significantly higher risk of developing heart failure. Increases in advanced glycation end products are a proposed pathophysiological link, but their impact and mechanism remain incompletely understood. Methylglyoxal (MG) is a glycolysis byproduct, elevated in diabetes, and modifies arginine and lysine residues. We show that left ventricular myofilament from patients with diabetes and heart failure (dbHF) exhibited increased MG modifications compared with nonfailing controls (NF) or heart failure patients without diabetes. In skinned NF human and mouse cardiomyocytes, acute MG treatment depressed both calcium sensitivity and maximal calcium-activated force in a dose-dependent manner. Importantly, dbHF myocytes were resistant to myofilament functional changes from MG treatment, indicating that myofilaments from dbHF patients already had depressed function arising from MG modifications. In human dbHF and MG-treated mice, mass spectrometry identified increased MG modifications on actin and myosin. Cosedimentation and in vitro motility assays indicate that MG modifications on actin and myosin independently depress calcium sensitivity, and mechanistically, the functional consequence requires actin/myosin interaction with thin-filament regulatory proteins. MG modification of the myofilament may represent a critical mechanism by which diabetes induces heart failure, as well as a therapeutic target to avoid the development of or ameliorate heart failure in these patients.
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Diabetes Mellitus Tipo 2/complicaciones , Insuficiencia Cardíaca/patología , Ventrículos Cardíacos/fisiopatología , Piruvaldehído/metabolismo , Sarcómeros/patología , Actinas/metabolismo , Adulto , Animales , Arginina/metabolismo , Cardiomiopatía Dilatada/patología , Diabetes Mellitus Tipo 2/metabolismo , Modelos Animales de Enfermedad , Femenino , Glucólisis , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/fisiopatología , Ventrículos Cardíacos/citología , Ventrículos Cardíacos/patología , Humanos , Lisina/metabolismo , Masculino , Ratones , Persona de Mediana Edad , Miosinas/metabolismo , Piruvaldehído/administración & dosificación , Sarcómeros/metabolismo , Sarcómeros/fisiología , Análisis de la Célula IndividualRESUMEN
Cardiac dyssynchrony arises from conduction abnormalities during heart failure and worsens morbidity and mortality. Cardiac resynchronization therapy (CRT) re-coordinates contraction using bi-ventricular pacing, but the cellular and molecular mechanisms involved remain largely unknown. The aim is to determine how dyssynchronous heart failure (HFdys ) alters the phospho-proteome and how CRT interacts with this unique phospho-proteome by analyzing Ser/Thr and Tyr phosphorylation. Phospho-enriched myocardium from dog models of Control, HFdys , and CRT is analyzed via MS. There were 209 regulated phospho-sites among 1761 identified sites. Compared to Con and CRT, HFdys is hyper-phosphorylated and tyrosine phosphorylation is more likely to be involved in signaling that increased with HFdys and was exacerbated by CRT. For each regulated site, the most-likely targeting-kinase is predicted, and CK2 is highly specific for sites that are "fixed" by CRT, suggesting activation of CK2 signaling occurs in HFdys that is reversed by CRT, which is supported by western blot analysis. These data elucidate signaling networks and kinases that may be involved and deserve further study. Importantly, a possible role for CK2 modulation in CRT has been identified. This may be harnessed in the future therapeutically to compliment CRT, improving its clinical effects.
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Biomarcadores/metabolismo , Terapia de Resincronización Cardíaca/métodos , Insuficiencia Cardíaca/metabolismo , Corazón/fisiología , Fosfoproteínas/metabolismo , Proteoma/análisis , Animales , Perros , Insuficiencia Cardíaca/patología , Insuficiencia Cardíaca/terapia , Fosfoproteínas/análisis , Fosforilación , Proteoma/metabolismo , Transducción de Señal , Espectrometría de Masas en Tándem , Resultado del TratamientoRESUMEN
RATIONALE: Disrupted proteostasis is one major pathological trait that heart failure (HF) shares with other organ proteinopathies, such as Alzheimer and Parkinson diseases. Yet, differently from the latter, whether and how cardiac preamyloid oligomers (PAOs) develop in acquired forms of HF is unclear. OBJECTIVE: We previously reported a rise in monophosphorylated, aggregate-prone desmin in canine and human HF. We now tested whether monophosphorylated desmin acts as the seed nucleating PAOs formation and determined whether positron emission tomography is able to detect myocardial PAOs in nongenetic HF. METHODS AND RESULTS: Here, we first show that toxic cardiac PAOs accumulate in the myocardium of mice subjected to transverse aortic constriction and that PAOs comigrate with the cytoskeletal protein desmin in this well-established model of acquired HF. We confirm this evidence in cardiac extracts from human ischemic and nonischemic HF. We also demonstrate that Ser31 phosphorylated desmin aggregates extensively in cultured cardiomyocytes. Lastly, we were able to detect the in vivo accumulation of cardiac PAOs using positron emission tomography for the first time in acquired HF. CONCLUSIONS: Ser31 phosphorylated desmin is a likely candidate seed for the nucleation process leading to cardiac PAOs deposition. Desmin post-translational processing and misfolding constitute a new, attractive avenue for the diagnosis and treatment of the cardiac accumulation of toxic PAOs that can now be measured by positron emission tomography in acquired HF.
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Amiloide/metabolismo , Desmina/metabolismo , Insuficiencia Cardíaca/metabolismo , Miocitos Cardíacos/metabolismo , Procesamiento Proteico-Postraduccional , Amiloide/análisis , Amiloide/efectos de los fármacos , Animales , Catequina/análogos & derivados , Catequina/farmacología , Células Cultivadas , Desmina/genética , Femenino , Vectores Genéticos , Insuficiencia Cardíaca/etiología , Humanos , Masculino , Espectrometría de Masas/métodos , Ratones , Ratones Noqueados , Mutagénesis Sitio-Dirigida , Isquemia Miocárdica/complicaciones , Fosforilación , Polimorfismo de Nucleótido Simple , Tomografía de Emisión de Positrones/métodos , Presión , Agregado de Proteínas/efectos de los fármacos , Pliegue de Proteína , Ratas , Proteínas Recombinantes/metabolismo , alfa-Cristalinas/deficiencia , beta-Cristalinas/deficienciaRESUMEN
Duchenne muscular dystrophy (DMD) is an X-linked disorder with dystrophin loss that results in skeletal and cardiac muscle weakening and early death. Loss of the dystrophin-sarcoglycan complex delocalizes nitric oxide synthase (NOS) to alter its signaling, and augments mechanosensitive intracellular Ca2+ influx. The latter has been coupled to hyperactivation of the nonselective cation channel, transient receptor potential canonical channel 6 (Trpc6), in isolated myocytes. As Ca2+ also activates NOS, we hypothesized that Trpc6 would help to mediate nitric oxide (NO) dysregulation and that this would be manifest in increased myocardial S-nitrosylation, a posttranslational modification increasingly implicated in neurodegenerative, inflammatory, and muscle disease. Using a recently developed dual-labeling proteomic strategy, we identified 1,276 S-nitrosylated cysteine residues [S-nitrosothiol (SNO)] on 491 proteins in resting hearts from a mouse model of DMD (dmdmdx:utrn+/-). These largely consisted of mitochondrial proteins, metabolic regulators, and sarcomeric proteins, with 80% of them also modified in wild type (WT). S-nitrosylation levels, however, were increased in DMD. Genetic deletion of Trpc6 in this model (dmdmdx:utrn+/-:trpc6-/-) reversed â¼70% of these changes. Trpc6 deletion also ameliorated left ventricular dilation, improved cardiac function, and tended to reduce fibrosis. Furthermore, under catecholamine stimulation, which also increases NO synthesis and intracellular Ca2+ along with cardiac workload, the hypernitrosylated state remained as it did at baseline. However, the impact of Trpc6 deletion on the SNO proteome became less marked. These findings reveal a role for Trpc6-mediated hypernitrosylation in dmdmdx:utrn+/- mice and support accumulating evidence that implicates nitrosative stress in cardiac and muscle disease.
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Distrofia Muscular de Duchenne/metabolismo , Miocardio/metabolismo , Canales Catiónicos TRPC/metabolismo , Animales , Señalización del Calcio , Cisteína/metabolismo , Modelos Animales de Enfermedad , Epinefrina/farmacología , Eliminación de Gen , Masculino , Ratones , Ratones Endogámicos C57BL , Distrofia Muscular de Duchenne/patología , Distrofia Muscular de Duchenne/fisiopatología , Nitrosación , S-Nitrosotioles/metabolismo , Simpatomiméticos/farmacología , Canales Catiónicos TRPC/genética , Canal Catiónico TRPC6 , Remodelación VentricularRESUMEN
Hypoxia-inducible factor 1 (HIF-1) activates the transcription of genes encoding proteins that enable cells to adapt to reduced O2 availability. Proteins encoded by HIF-1 target genes play a central role in mediating physiological processes that are dysregulated in cancer and heart disease. These diseases are also characterized by increased production of cyclic adenosine monophosphate (cAMP), the allosteric activator of cAMP-dependent protein kinase A (PKA). Using glutathione S-transferase pull-down, coimmunoprecipitation, and mass spectrometry analyses, we demonstrated that PKA interacts with HIF-1α in HeLa cervical carcinoma cells and rat cardiomyocytes. PKA phosphorylated Thr(63) and Ser(692) on HIF-1α in vitro and enhanced HIF transcriptional activity and target gene expression in HeLa cells and rat cardiomyocytes. PKA inhibited the proteasomal degradation of HIF-1α in an O2-independent manner that required the phosphorylation of Thr(63) and Ser(692) and was not affected by prolyl hydroxylation. PKA also stimulated the binding of the coactivator p300 to HIF-1α to enhance its transcriptional activity and counteracted the inhibitory effect of asparaginyl hydroxylation on the association of p300 with HIF-1α. Furthermore, increased cAMP concentrations enhanced the expression of HIF target genes encoding CD39 and CD73, which are enzymes that convert extracellular adenosine 5'-triphosphate to adenosine, a molecule that enhances tumor immunosuppression and reduces heart rate and contractility. These data link stimuli that promote cAMP signaling, HIF-1α-dependent changes in gene expression, and increased adenosine, all of which contribute to the pathophysiology of cancer and heart disease.
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Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Transcripción Genética , 5'-Nucleotidasa/metabolismo , Animales , Antígenos CD/metabolismo , Apirasa/metabolismo , AMP Cíclico/metabolismo , Progresión de la Enfermedad , Proteínas Ligadas a GPI/metabolismo , Glutatión Transferasa/metabolismo , Células HeLa , Humanos , Terapia de Inmunosupresión , Ratones , Miocitos Cardíacos/metabolismo , Fosforilación , Unión ProteicaRESUMEN
Data independent acquisition (DIA also termed SWATH) is an emerging technology in the field of mass spectrometry based proteomics. Although the concept of DIA has been around for over a decade, the recent advancements, in particular the speed of acquisition, of mass analyzers have pushed the technique into the spotlight and allowed for high-quality DIA data to be routinely acquired by proteomics labs. In this chapter we will discuss the protocols used for DIA acquisition using the Sciex TripleTOF mass spectrometers and data analysis using the Sciex processing software.
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Espectrometría de Masas/métodos , Proteómica/métodos , Programas Informáticos , HumanosRESUMEN
The protective role of cyclic guanosine monophosphate (cGMP)-stimulated protein kinase G (PKG) in the heart makes it an attractive target for therapeutic drug development to treat a variety of cardiac diseases. Phosphodiesterases degrade cGMP, thus phosphodiesterase inhibitors that can increase PKG are of translational interest and the subject of ongoing human trials. PKG signaling is complex, however, and understanding its downstream phosphorylation targets and upstream regulation are necessary steps toward safe and efficacious drug development. Proteomic technologies have paved the way for assays that allow us to peer broadly into signaling minutia, including protein quantity changes and phosphorylation events. However, there are persistent challenges to the proteomic study of PKG, such as the impact of the expression of different PKG isoforms, changes in its localization within the cell, and alterations caused by oxidative stress. PKG signaling is also dependent upon sex and potentially the genetic and epigenetic background of the individual. Thus, the rigorous application of proteomics to the field will be necessary to address how these effectors can alter PKG signaling and interfere with pharmacological interventions. This review will summarize PKG signaling, how it is being targeted clinically, and the proteomic challenges and techniques that are being used to study it.
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Proteínas Quinasas Dependientes de GMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Descubrimiento de Drogas/métodos , Cardiopatías/tratamiento farmacológico , Cardiopatías/patología , Corazón/fisiopatología , Secuencia de Aminoácidos , Animales , Bovinos , Humanos , Ratones , Ratas , Transducción de SeñalRESUMEN
Protein kinase C-δ (PKCδ) is a signalling kinase that regulates many cellular responses. Although most studies focus on allosteric mechanisms that activate PKCδ at membranes, PKCδ also is controlled via multi-site phosphorylation [Gong et al. (2015) Mol. Cell. Biol. 35: , 1727-1740]. The present study uses MS-based methods to identify PKCδ phosphorylation at Thr(50) and Ser(645) (in resting and PMA-treated cardiomyocytes) as well as Thr(37), Thr(38), Ser(130), Thr(164), Thr(211), Thr(215), Ser(218), Thr(295), Ser(299) and Thr(656) (as sites that increase with PMA). We focused on the consequences of phosphorylation at Ser(130) and Thr(141) (sites just N-terminal to the pseudosubstrate domain). We show that S130D and T141E substitutions co-operate to increase PKCδ's basal lipid-independent activity and that Ser(130)/Thr(141) di-phosphorylation influences PKCδ's substrate specificity. We recently reported that PKCδ preferentially phosphorylates substrates with a phosphoacceptor serine residue and that this is due to constitutive phosphorylation at Ser(357), an ATP-positioning G-loop site that limits PKCδ's threonine kinase activity [Gong et al. (2015) Mol. Cell. Biol. 35: , 1727-1740]. The present study shows that S130D and T141E substitutions increase PKCδ's threonine kinase activity indirectly by decreasing G loop phosphorylation at Ser(357). A S130F substitution [that mimics a S130F single-nt polymorphism (SNP) identified in some human populations] also increases PKCδ's maximal lipid-dependent catalytic activity and confers threonine kinase activity. Finally, we show that Ser(130)/Thr(141) phosphorylations relieve auto-inhibitory constraints that limit PKCδ's activity and substrate specificity in a cell-based context. Since phosphorylation sites map to similar positions relative to the pseudosubstrate domains of other PKCs, our results suggest that phosphorylation in this region of the enzyme may constitute a general mechanism to control PKC isoform activity.
Asunto(s)
Proteína Quinasa C-delta/química , Proteína Quinasa C-delta/metabolismo , Serina/metabolismo , Secuencia de Aminoácidos , Animales , Activación Enzimática , Humanos , Datos de Secuencia Molecular , Miocitos Cardíacos/enzimología , Fosforilación , Proteína Quinasa C-delta/genética , Estructura Terciaria de Proteína , Ratas , Ratas Wistar , Alineación de Secuencia , Especificidad por SustratoRESUMEN
Uncoordinated contraction from electromechanical delay worsens heart failure pathophysiology and prognosis, but restoring coordination with biventricular pacing, known as cardiac resynchronization therapy (CRT), improves both. However, not every patient qualifies for CRT. We show that heart failure with synchronous contraction is improved by inducing dyssynchrony for 6 hours daily by right ventricular pacing using an intracardiac pacing device, in a process we call pacemaker-induced transient asynchrony (PITA). In dogs with heart failure induced by 6 weeks of atrial tachypacing, PITA (starting on week 3) suppressed progressive cardiac dilation as well as chamber and myocyte dysfunction. PITA enhanced ß-adrenergic responsiveness in vivo and normalized it in myocytes. Myofilament calcium response declined in dogs with synchronous heart failure, which was accompanied by sarcomere disarray and generation of myofibers with severely reduced function, and these changes were absent in PITA-treated hearts. The benefits of PITA were not replicated when the same number of right ventricular paced beats was randomly distributed throughout the day, indicating that continuity of dyssynchrony exposure is necessary to trigger the beneficial biological response upon resynchronization. These results suggest that PITA could bring the benefits of CRT to the many heart failure patients with synchronous contraction who are not CRT candidates.
Asunto(s)
Progresión de la Enfermedad , Insuficiencia Cardíaca/patología , Insuficiencia Cardíaca/terapia , Marcapaso Artificial , Animales , Calcio/metabolismo , Perros , Insuficiencia Cardíaca/fisiopatología , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Miofibrillas/metabolismo , Proteómica , Receptores Adrenérgicos beta/metabolismo , Sarcómeros/metabolismoRESUMEN
AIMS: Citrullination, the post-translational conversion of arginine to citrulline by the enzyme family of peptidylarginine deiminases (PADs), is associated with several diseases, and specific citrullinated proteins have been shown to alter function while others act as auto-antigens. In this study, we identified citrullinated proteins in human myocardial samples, from healthy and heart failure patients, and determined several potential functional consequences. Further we investigated PAD isoform cell-specific expression in the heart. METHODS AND RESULTS: A citrullination-targeted proteomic strategy using data-independent (SWATH) acquisition method was used to identify the modified cardiac proteins. Citrullinated-induced sarcomeric proteins were validated using two-dimensional gel electrophoresis and investigated using biochemical and functional assays. Myocardial PAD isoforms were confirmed by RT-PCR with PAD2 being the major isoform in myocytes. In total, 304 citrullinated sites were identified that map to 145 proteins among the three study groups: normal, ischaemia, and dilated cardiomyopathy. Citrullination of myosin (using HMM fragment) decreased its intrinsic ATPase activity and inhibited the acto-HMM-ATPase activity. Citrullinated TM resulted in stronger F-actin binding and inhibited the acto-HMM-ATPase activity. Citrullinated TnI did not alter the binding to F-actin or acto-HMM-ATPase activity. Overall, citrullination of sarcomeric proteins caused a decrease in Ca(2+) sensitivity in skinned cardiomyocytes, with no change in maximal calcium-activated force or hill coefficient. CONCLUSION: Citrullination unique to the cardiac proteome was identified. Our data indicate important structural and functional alterations to the cardiac sarcomere and the contribution of protein citrullination to this process.