RESUMO
Dilated cardiomyopathy caused by mutations in LMNA, encoding A-type lamins (i.e., LMNA cardiomyopathy), is characterized by a left ventricle enlargement and ultimately results in poor cardiac contractility associated with conduction defects. Despite current strategies to aggressively manage the symptoms, the disorder remains a common cause of sudden death and heart failure with decreased ejection fraction. Patient care includes cardioverter defibrillator implantation but the last therapeutic option remains cardiac transplantation. A-type lamins are intermediate filaments and are the main components of the nuclear lamina, a meshwork underlying the inner nuclear membrane, which plays an essential role in both maintaining the nuclear structure and organizing the cytoskeletal structures within the cell. Cytoskeletal proteins function as scaffold to resist external mechanical stress. An increasing amount of evidence demonstrates that LMNA mutations can lead to disturbances in several structural and cytoskeletal components of the cell such as microtubules, actin cytoskeleton, and intermediate filaments. Collectively, this review focuses on the significance of these cytoskeletal modulators and emphasizes their potential therapeutic role in LMNA cardiomyopathy. Indeed, molecular tuning of cytoskeletal dynamics has been successfully used in preclinical models and provides adequate grounds for a therapeutic approach for patients with LMNA cardiomyopathy.
Assuntos
Cardiomiopatias , Lamina Tipo A , Humanos , Lamina Tipo A/genética , Lamina Tipo A/metabolismo , Cardiomiopatias/genética , Cardiomiopatias/terapia , Cardiomiopatias/metabolismo , Citoesqueleto/genética , Citoesqueleto/metabolismo , Microtúbulos/metabolismo , Mutação/genéticaRESUMO
Mutations in the lamin A/C gene (LMNA), which encodes A-type lamins, cause several diseases called laminopathies, the most common of which is dilated cardiomyopathy with muscular dystrophy. The role of Ca2+ regulation in these diseases remain poorly understood. We now show biochemical remodeling of the ryanodine receptor (RyR)/intracellular Ca2+ release channel in heart samples from human subjects with LMNA mutations, including protein kinase A-catalyzed phosphorylation, oxidation and depletion of the stabilizing subunit calstabin. In the LmnaH222P/H222P murine model of Emery-Dreifuss muscular dystrophy caused by LMNA mutation, we demonstrate an age-dependent biochemical remodeling of RyR2 in the heart and RyR1 in skeletal muscle. This RyR remodeling is associated with heart and skeletal muscle dysfunction. Defective heart and muscle function are ameliorated by treatment with a novel Rycal small molecule drug (S107) that fixes 'leaky' RyRs. SMAD3 phosphorylation is increased in hearts and diaphragms of LmnaH222P/H222P mice, which enhances NADPH oxidase binding to RyR channels, contributing to their oxidation. There is also increased generalized protein oxidation, increased calcium/calmodulin-dependent protein kinase II-catalyzed phosphorylation of RyRs and increased protein kinase A activity in these tissues. Our data show that RyR remodeling plays a role in cardiomyopathy and skeletal muscle dysfunction caused by LMNA mutation and identify these Ca2+ channels as a potential therapeutic target.
Assuntos
Cardiomiopatias/patologia , Modelos Animais de Doenças , Coração/fisiopatologia , Lamina Tipo A/genética , Distrofias Musculares/patologia , Mutação , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Animais , Sinalização do Cálcio , Cardiomiopatias/etiologia , Cardiomiopatias/metabolismo , Feminino , Homeostase , Humanos , Masculino , Camundongos , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Distrofias Musculares/etiologia , Distrofias Musculares/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/genéticaRESUMO
What if the next generation of successful treatments was hidden in the current pharmacopoeia? Identifying new indications for existing drugs, also called the drug repurposing or drug rediscovery process, is a highly efficient and low-cost strategy. First reported almost a century ago, drug repurposing has emerged as a valuable therapeutic option for diseases that do not have specific treatments and rare diseases, in particular. This review focuses on Hutchinson-Gilford progeria syndrome (HGPS), a rare genetic disorder that induces accelerated and precocious aging, for which drug repurposing has led to the discovery of several potential treatments over the past decade.
Assuntos
Progéria , Humanos , Lamina Tipo A/genética , Preparações Farmacêuticas , Progéria/tratamento farmacológico , Progéria/genéticaRESUMO
Autosomal Emery-Dreifuss muscular dystrophy (EDMD) is caused by mutations in the lamin A/C gene (LMNA) encoding A-type nuclear lamins, intermediate filament proteins of the nuclear envelope. Classically, the disease manifests as scapulo-humero-peroneal muscle wasting and weakness, early joint contractures and dilated cardiomyopathy with conduction blocks; however, variable skeletal muscle involvement can be present. Previously, we and other demonstrated altered activity of signaling pathways in hearts and striated muscles of LmnaH222P/H222P mice, a model of autosomal EDMD. We showed that blocking their activation improved cardiac function. However, the evaluation of the benefit of these treatments on the whole organism is suffering from a better knowledge of the performance in mouse models. We show in the present study that LmnaH222P/H222P mice display a significant loss of lean mass, consistent with the dystrophic process. This is associated with altered VO2 peak and respiratory exchange ratio. These results showed for the first time that LmnaH222P/H222P mice have decreased performance and provided a new useful means for future therapeutic interventions on this model of EDMD.
Assuntos
Lamina Tipo A/genética , Distrofia Muscular de Emery-Dreifuss/genética , Animais , Composição Corporal , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Transgênicos , Distrofia Muscular de Emery-Dreifuss/metabolismo , Distrofia Muscular de Emery-Dreifuss/fisiopatologia , Mutação , Função Ventricular Esquerda , Redução de PesoRESUMO
Mutations in the lamin A/C gene (LMNA) cause an autosomal dominant inherited form of dilated cardiomyopathy associated with cardiac conduction disease (hereafter referred to as LMNA cardiomyopathy). Compared with other forms of dilated cardiomyopathy, mutations in LMNA are responsible for a more aggressive clinical course owing to a high rate of malignant ventricular arrhythmias. Gap junctions are intercellular channels that allow direct communication between neighboring cells, which are involved in electrical impulse propagation and coordinated contraction of the heart. For gap junctions to properly control electrical synchronization in the heart, connexin-based hemichannels must be correctly targeted to intercalated discs, Cx43 being the major connexin in the working myocytes. We here showed an altered distribution of Cx43 in a mouse model of LMNA cardiomyopathy. However, little is known on the molecular mechanisms of Cx43 remodeling in pathological context. We now show that microtubule cytoskeleton alteration and decreased acetylation of α-tubulin lead to remodeling of Cx43 in LMNA cardiomyopathy, which alters the correct communication between cardiomyocytes, ultimately leading to electrical conduction disturbances. Preventing or reversing this process could offer a strategy to repair damaged heart. Stabilization of microtubule cytoskeleton using Paclitaxel improved intraventricular conduction defects. These results indicate that microtubule cytoskeleton contributes to the pathogenesis of LMNA cardiomyopathy and that drugs stabilizing the microtubule may be beneficial for patients.
Assuntos
Cardiomiopatias/genética , Cardiomiopatias/metabolismo , Conexina 43/metabolismo , Lamina Tipo A/genética , Paclitaxel/farmacologia , Acetilação/efeitos dos fármacos , Animais , Doença do Sistema de Condução Cardíaco/genética , Cardiomiopatias/patologia , Conexina 43/genética , Citoesqueleto/metabolismo , Citoesqueleto/patologia , Junções Comunicantes/efeitos dos fármacos , Junções Comunicantes/metabolismo , Junções Comunicantes/patologia , Lamina Tipo A/metabolismo , Masculino , Camundongos , Camundongos Knockout , Microtúbulos/metabolismo , Microtúbulos/patologia , Mutação , Miocárdio/patologia , Miócitos Cardíacos/patologiaRESUMO
The expression of α-cardiac actin, a major constituent of the cytoskeleton of cardiomyocytes, is dramatically decreased in a mouse model of dilated cardiomyopathy triggered by inducible cardiac-specific serum response factor (Srf) gene disruption that could mimic some forms of human dilated cardiomyopathy. To investigate the consequences of the maintenance of α-cardiac actin expression in this model, we developed a new transgenic mouse based on Cre/LoxP strategy, allowing together the induction of SRF loss and a compensatory expression of α-cardiac actin. Here, we report that maintenance of α-cardiac actin within cardiomyocytes temporally preserved cytoarchitecture from adverse cardiac remodeling through a positive impact on both structural and transcriptional levels. These protective effects were accompanied in vivo by the decrease of ROS generation and protein carbonylation and the downregulation of NADPH oxidases NOX2 and NOX4. We also show that ectopic expression of α-cardiac actin protects HEK293 cells against oxidative stress induced by H2 O2 . Oxidative stress plays an important role in the development of cardiac remodeling and contributes also to the pathogenesis of heart failure. Taken together, these findings indicate that α-cardiac actin could be involved in the regulation of oxidative stress that is a leading cause of adverse remodeling during dilated cardiomyopathy development.
Assuntos
Actinas/metabolismo , Cardiomiopatia Dilatada/metabolismo , Miócitos Cardíacos/metabolismo , Estresse Oxidativo , Actinas/genética , Animais , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/patologia , Cardiomiopatia Dilatada/prevenção & controle , Modelos Animais de Doenças , Feminino , Humanos , Peróxido de Hidrogênio/farmacologia , Masculino , Camundongos , Camundongos Transgênicos , Miócitos Cardíacos/patologia , NADPH Oxidase 2/genética , NADPH Oxidase 2/metabolismo , NADPH Oxidase 4/genética , NADPH Oxidase 4/metabolismoRESUMO
Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopathy) is an anatomic and pathologic condition associated with muscle and electrical dysfunction of the heart, often leading to heart failure-related disability. There is currently no specific therapy available for patients that target the molecular pathophysiology of LMNA cardiomyopathy. Recent studies suggested that nicotinamide adenine dinucleotide (NAD+) cellular content could be a critical determinant for heart function. Biosynthesis of NAD+ from vitamin B3 (known as salvage pathways) is the primary source of NAD+. We showed here that NAD+ salvage pathway was altered in the heart of mouse and human carrying LMNA mutation, leading to an alteration of one of NAD+ co-substrate enzymes, PARP-1. Oral administration of nicotinamide riboside, a natural NAD+ precursor and a pyridine-nucleoside form of vitamin B3, leads to a marked improvement of the NAD+ cellular content, an increase of PARylation of cardiac proteins and an improvement of left ventricular structure and function in a model of LMNA cardiomyopathy. Collectively, our results provide mechanistic and therapeutic insights into dilated cardiomyopathy caused by LMNA mutations.
Assuntos
Cardiomiopatias/genética , Coração/fisiopatologia , Lamina Tipo A/genética , NAD/genética , Poli(ADP-Ribose) Polimerase-1/genética , Animais , Cardiomiopatias/fisiopatologia , Modelos Animais de Doenças , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/fisiopatologia , Ventrículos do Coração/metabolismo , Ventrículos do Coração/fisiopatologia , Humanos , Camundongos , Mutação , NAD/biossíntese , Niacinamida/genética , Niacinamida/metabolismo , Poli ADP Ribosilação/genética , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/fisiopatologiaRESUMO
Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopathy) is an anatomic and pathologic condition associated with muscular and electrical dysfunction of the heart, often leading to heart failure-related disability. There is currently no specific therapy available for patients that target the molecular pathophysiology of LMNA cardiomyopathy. We showed here an increase in oxidative stress levels in the hearts of mice carrying LMNA mutation, associated with a decrease of the key cellular antioxidant glutathione (GHS). Oral administration of N-acetyl cysteine, a GHS precursor, led to a marked improvement of GHS content, a decrease in oxidative stress markers including protein carbonyls and an improvement of left ventricular structure and function in a model of LMNA cardiomyopathy. Collectively, our novel results provide therapeutic insights into LMNA cardiomyopathy.
Assuntos
Acetilcisteína/administração & dosagem , Cardiomiopatia Dilatada/genética , Insuficiência Cardíaca/genética , Lamina Tipo A/genética , Acetilcisteína/metabolismo , Animais , Antioxidantes/administração & dosagem , Antioxidantes/metabolismo , Cardiomiopatia Dilatada/tratamento farmacológico , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/fisiopatologia , Modelos Animais de Doenças , Glutationa/metabolismo , Coração/efeitos dos fármacos , Coração/fisiopatologia , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/patologia , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/fisiopatologia , Humanos , Camundongos , Mutação , Miocárdio/patologia , Estresse Oxidativo/efeitos dos fármacosRESUMO
Hyper-activation of extracellular signal-regulated kinase (ERK) 1/2 contributes to heart dysfunction in cardiomyopathy caused by mutations in the lamin A/C gene (LMNA cardiomyopathy). The mechanism of how this affects cardiac function is unknown. We show that active phosphorylated ERK1/2 directly binds to and catalyzes the phosphorylation of the actin depolymerizing factor cofilin-1 on Thr25. Cofilin-1 becomes active and disassembles actin filaments in a large array of cellular and animal models of LMNA cardiomyopathy. In vivo expression of cofilin-1, phosphorylated on Thr25 by endogenous ERK1/2 signaling, leads to alterations in left ventricular function and cardiac actin. These results demonstrate a novel role for cofilin-1 on actin dynamics in cardiac muscle and provide a rationale on how increased ERK1/2 signaling leads to LMNA cardiomyopathy.
Assuntos
Actinas/metabolismo , Cardiomiopatia Dilatada/patologia , Cofilina 1/metabolismo , Lamina Tipo A/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Mutação , Actinas/genética , Adolescente , Adulto , Animais , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/metabolismo , Estudos de Casos e Controles , Cofilina 1/genética , Feminino , Coração/fisiologia , Humanos , Lamina Tipo A/metabolismo , Masculino , Camundongos , Pessoa de Meia-Idade , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/genética , Fosforilação , Transdução de Sinais , Adulto JovemRESUMO
The cytoskeleton is a complex network interlinking filaments that extend throughout the cytoplasm from the nucleus to the plasma membrane. Three major types of filaments are found in the cytoskeleton: actin filaments, microtubules, and intermediate filaments. They play a key role in the ability of cells to both resist mechanical stress and generate force. However, the precise involvement of intermediate filament proteins in these processes remains unclear. Here, we focused on nuclear A-type lamins, which are connected to the cytoskeleton via the Linker of Nucleoskeleton and Cytoskeleton (LINC) complex. Using micro-constriction rheology, we investigated the impact of A-type lamins (p.H222P) mutation on the mechanical properties of muscle cells. We demonstrate that the expression of point mutation of lamin A in muscle cells increases cellular stiffness compared with cells expressing wild type lamin A and that the chemical agent selumetinib, an inhibitor of the ERK1/2 signaling, reversed the mechanical alterations in mutated cells. These results highlight the interplay between A-type lamins and mechano-signaling, which are supported by cell biology measurements.
Assuntos
Lamina Tipo A/genética , Fibras Musculares Esqueléticas/citologia , Mutação Puntual , Animais , Fenômenos Biomecânicos , Linhagem Celular , Lamina Tipo A/metabolismo , Sistema de Sinalização das MAP Quinases , Camundongos , Fibras Musculares Esqueléticas/metabolismoRESUMO
Cardiomyopathy caused by lamin A/C gene (LMNA) mutations (hereafter referred as LMNA cardiomyopathy) is characterized by cardiac conduction abnormalities and left ventricular systolic dysfunction predisposing to heart failure. Previous cardiac transcriptional profiling of LmnaH222P/H222P mouse, a small animal model of LMNA cardiomyopathy, suggested decreased WNT/ß-catenin signalling. We confirmed decreased WNT/ß-catenin signalling in the hearts of these mice by demonstrating decreased ß-catenin and WNT proteins. This was correlated with increased expression of soluble Frizzled-related proteins that modulate the WNT/ß-catenin signalling pathway. Hearts of LmnaH222P/H222P mice also demonstrated lowered expression of the gap junction connexin 43. Activation of WNT/ß-catenin activity with 6-bromoindirubin-3'-oxime improved cardiac contractility and ameliorated intraventricular conduction defects in LmnaH222P/H222P mice, which was associated with increased expression of myocardial connexin 43. These results indicate that decreased WNT/ß-catenin contributes to the pathophysiology of LMNA cardiomyopathy and that drugs activating ß-catenin may be beneficial in affected individuals.
Assuntos
Cardiomiopatia Dilatada/genética , Conexina 43/genética , Lamina Tipo A/genética , beta Catenina/genética , Animais , Cardiomiopatia Dilatada/tratamento farmacológico , Cardiomiopatia Dilatada/fisiopatologia , Conexina 43/biossíntese , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Glicoproteínas/biossíntese , Glicoproteínas/genética , Insuficiência Cardíaca/tratamento farmacológico , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/fisiopatologia , Humanos , Indóis/administração & dosagem , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Mutação , Oximas/administração & dosagem , Disfunção Ventricular Esquerda/tratamento farmacológico , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/fisiopatologia , Proteínas Wnt/genética , Via de Sinalização Wnt/efeitos dos fármacos , beta Catenina/biossínteseRESUMO
PURPOSE OF REVIEW: Emery-Dreifuss muscular dystrophy (EDMD) is caused by mutations in EMD encoding emerin and LMNA encoding A-type lamins, proteins of the nuclear envelope. In the past decade, there has been an extraordinary burst of research on the nuclear envelope. Discoveries resulting from this basic research have implications for better understanding the pathogenesis and developing treatments for EDMD. RECENT FINDINGS: Recent clinical research has confirmed that EDMD is one of several overlapping skeletal muscle phenotypes that can result from mutations in EMD and LMNA with dilated cardiomyopathy as a common feature. Basic research on the nuclear envelope has provided new insights into how A-type lamins and emerin function in force transmission throughout the cell, which may be particularly important in striated muscle. Much of the recent research has focused on the heart and LMNA mutations. Prevalence and outcome studies have confirmed the relative severity of cardiac disease. Robust mouse models of EDMD caused by LMNA mutations has allowed for further insight into pathogenic mechanisms and potentially beneficial therapeutic approaches. SUMMARY: Recent clinical and basic research on EDMD is gradually being translated to clinical practice and possibly novel therapies.
Assuntos
Lamina Tipo A/metabolismo , Proteínas de Membrana/metabolismo , Distrofia Muscular de Emery-Dreifuss/genética , Mutação , Membrana Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Animais , Humanos , Lamina Tipo A/genética , Proteínas de Membrana/genética , Camundongos , Músculo Esquelético/metabolismo , Distrofia Muscular de Emery-Dreifuss/metabolismo , Proteínas Nucleares/genética , FenótipoRESUMO
Cardiomyopathy caused by lamin A/C gene mutations (LMNA cardiomyopathy) is characterized by increased myocardial fibrosis, which impairs left ventricular relaxation and predisposes to heart failure, and cardiac conduction abnormalities. While we previously discovered abnormally elevated extracellular signal-regulated kinase 1/2 (ERK1/2) activities in heart in LMNA cardiomyopathy, its role on the development of myocardial fibrosis remains unclear. We now showed that transforming growth factor (TGF)-ß/Smad signaling participates in the activation of ERK1/2 signaling in LMNA cardiomyopathy. ERK1/2 acts on connective tissue growth factor (CTGF/CCN2) expression to mediate the myocardial fibrosis and left ventricular dysfunction. Studies in vivo demonstrate that inhibiting CTGF/CCN2 using a specific antibody decreases myocardial fibrosis and improves the left ventricular dysfunction. Together, these findings show that cardiac ERK1/2 activity is modulated in part by TGF-ß/Smad signaling, leading to altered activation of CTGF/CCN2 to mediate fibrosis and alter cardiac function. This identifies a novel mechanism in the development of LMNA cardiomyopathy.
Assuntos
Cardiomiopatias/genética , Fator de Crescimento do Tecido Conjuntivo/genética , Fibrose/genética , Lamina Tipo A/genética , Fator de Crescimento Transformador beta/genética , Animais , Cardiomiopatias/patologia , Fibrose/patologia , Humanos , Sistema de Sinalização das MAP Quinases/genética , Camundongos , Camundongos Knockout , Miocárdio/metabolismo , Miocárdio/patologia , Proteínas Smad/genética , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/patologiaRESUMO
Mutations in genes encoding components of the sarcomere cause cardiomyopathy, which is often associated with abnormal Ca2+ sensitivity of muscle contraction. We have previously shown that a heart-specific myosin light chain phosphatase small subunit (hHS-M21) increases the Ca2+ sensitivity of muscle contraction. The aim of the present study was to investigate the function of hHS-M21 in vivo and the causative role of abnormal Ca2+ sensitivity in cardiomyopathy. We generated transgenic mice with cardiac-specific overexpression of hHS-M21. We confirmed that hHS-M21 increased the Ca2+ sensitivity of cardiac muscle contraction in vivo, which was not followed by an increased phosphorylation of myosin light chain 2 isoforms. hHS-M21 transgenic mice developed severe systolic dysfunction with myocardial fibrosis and degeneration of cardiomyocytes in association with sinus bradycardia and atrioventricular conduction defect. The contractile dysfunction and cardiac fibrosis were improved by treatment with the Rho kinase inhibitor fasudil. Our findings suggested that the overexpression of hHS-M21 results in cardiac dysfunction and conduction disturbance via non-myosin light chain 2 phosphorylation-dependent regulation. NEW & NOTEWORTHY The present study is the first to develop mice with transgenic overexpression of a heart-specific myosin light chain phosphatase small subunit (hHS-M21) and to examine the effects of hHS-M21 on cardiac function. Elevation of hHS-M21 induced heart failure with myocardial fibrosis and degeneration of cardiomyocytes accompanied by supraventricular arrhythmias.
Assuntos
Arritmias Cardíacas/enzimologia , Insuficiência Cardíaca/enzimologia , Miócitos Cardíacos/enzimologia , Fosfatase de Miosina-de-Cadeia-Leve/metabolismo , Animais , Arritmias Cardíacas/genética , Arritmias Cardíacas/patologia , Arritmias Cardíacas/fisiopatologia , Sinalização do Cálcio , Miosinas Cardíacas/metabolismo , Cardiomiopatias/enzimologia , Cardiomiopatias/genética , Cardiomiopatias/fisiopatologia , Modelos Animais de Doenças , Fibrose , Predisposição Genética para Doença , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/fisiopatologia , Frequência Cardíaca , Humanos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Contração Miocárdica , Miócitos Cardíacos/patologia , Cadeias Leves de Miosina/metabolismo , Fosfatase de Miosina-de-Cadeia-Leve/genética , Fenótipo , Fosforilação , Subunidades Proteicas , Regulação para Cima , Disfunção Ventricular Esquerda/enzimologia , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/fisiopatologia , Função Ventricular Esquerda , Remodelação Ventricular , Quinases Associadas a rho/metabolismoRESUMO
Signaling mediated by extracellular signal-regulated kinases 1 and 2 (ERK1/2) is involved in numerous cellular processes. Mitogen-activated protein kinase kinases (MEK1/2) catalyze the phosphorylation of ERK1/2, converting it into an active kinase that regulates the expression of numerous genes and cellular processes. Inhibitors of MEK1/2 have demonstrated preclinical and clinical efficacy in certain cancers and types of cardiomyopathy. We report the synthesis of a novel, allosteric, macrocyclic MEK1/2 inhibitor that potently inhibits ERK1/2 activity in cultured cells and tissues of mice after systemic administration. Mice with dilated cardiomyopathy caused by a lamin A/C gene mutation have abnormally increased cardiac ERK1/2 activity. In these mice, this novel MEK1/2 inhibitor is well tolerated, improves left ventricular systolic function, decreases left ventricular fibrosis, has beneficial effects on skeletal muscle structure and pathology and prolongs survival. The novel MEK1/2 inhibitor described herein may therefore find clinical utility in the treatment of this rare cardiomyopathy, other types of cardiomyopathy and cancers in humans.
Assuntos
Cardiomiopatia Dilatada/tratamento farmacológico , Modelos Animais de Doenças , Lamina Tipo A/genética , Compostos Macrocíclicos/farmacologia , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Inibidores de Proteínas Quinases/farmacologia , Animais , Cardiomiopatia Dilatada/genética , Relação Dose-Resposta a Droga , Compostos Macrocíclicos/administração & dosagem , Compostos Macrocíclicos/química , Camundongos , Camundongos Transgênicos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Estrutura Molecular , Mutação , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/química , Relação Estrutura-AtividadeRESUMO
Lamins A and C, encoded by LMNA, are constituent of the nuclear lamina, a meshwork of proteins underneath the nuclear envelope first described as scaffolding proteins of the nucleus. Since the discovery of LMNA mutations in highly heterogeneous human disorders (including cardiac and muscular dystrophies, lipodystrophies and progeria), the number of functions described for lamin A/C has expanded. Lamin A/C is notably involved in the regulation of chromatin structure and gene transcription, and in the resistance of cells to mechanical stress. This review focuses on studies performed on knock-out and knock-in Lmna mouse models, which have led to decipher some of the lamin A/C functions in striated muscles and to the first preclinical trials of pharmaceutical therapies.
Assuntos
Cardiomiopatias/genética , Lamina Tipo A/genética , Músculo Estriado/patologia , Distrofias Musculares/genética , Lâmina Nuclear/genética , Citoesqueleto de Actina/patologia , Animais , Cardiomiopatias/tratamento farmacológico , Cardiomiopatias/patologia , Desmina/genética , Modelos Animais de Doenças , Regulação da Expressão Gênica/genética , Técnicas de Introdução de Genes , Humanos , Camundongos , Camundongos Knockout , Músculo Estriado/citologia , Membrana Nuclear , Vimentina/genéticaRESUMO
Mutations in the lamin A/C gene (LMNA) encoding A-type nuclear lamins cause dilated cardiomyopathy with variable muscular dystrophy. These mutations enhance mitogen-activated protein kinase signaling in the heart and pharmacological inhibition of extracellular signal-regulated kinase (ERK) 1 and 2 improves cardiac function in Lmna(H222P/H222P) mice. In the current study, we crossed mice lacking ERK1 to Lmna(H222P/H222P) mice and examined cardiac performance and survival. Male Lmna(H222P/H222P)/Erk1(-/-) mice lacking ERK1 had smaller left ventricular end systolic diameters and increased fractional shortening (FS) at 16 weeks of age than Lmna(H222P/H222P/)Erk1(+/+) mice. Their mean survival was also significantly longer. However, the improved cardiac function was abrogated at 20 weeks of age concurrent with an increased activity of ERK2. Lmna(H222P/H222P)/Erk1(-/-) mice treated with an inhibitor of ERK1/2 activation had smaller left ventricular diameters and increased FS at 20 weeks of age. These results provide genetic evidence that ERK1 and ERK2 contribute to the development of cardiomyopathy caused by LMNA mutations and reveal interplay between these isoenzymes in maintaining a combined pathological activity in heart.
Assuntos
Cardiomiopatias/genética , Cardiomiopatias/fisiopatologia , Lamina Tipo A/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Animais , Benzimidazóis/farmacologia , Cardiomiopatias/patologia , Modelos Animais de Doenças , Feminino , Regulação da Expressão Gênica , Ventrículos do Coração/efeitos dos fármacos , Ventrículos do Coração/fisiopatologia , Humanos , Lamina Tipo A/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/genética , MutaçãoRESUMO
We previously interrogated the transcriptome in heart tissue from Lmna(H222P/H222P) mice, a mouse model of cardiomyopathy caused by lamin A/C gene (LMNA) mutation, and found that the extracellular signal-regulated kinase 1/2 and Jun N-terminal kinase branches of the mitogen-activated protein (MAP) kinase signaling pathway were abnormally hyperactivated prior to the onset of significant cardiac impairment. We have now used an alternative gene expression analysis tool to reanalyze this transcriptome and identify hyperactivation of a third branch of the MAP kinase cascade, p38α signaling. Biochemical analysis of hearts from Lmna(H222P/H222P) mice showed enhanced p38α activation prior to and after the onset of heart disease as well as in hearts from human subjects with cardiomyopathy caused by LMNA mutations. Treatment of Lmna(H222P/H222P) mice with the p38α inhibitor ARRY-371797 prevented left ventricular dilatation and deterioration of fractional shortening compared with placebo-treated mice but did not block the expression of collagen genes involved in cardiac fibrosis. These results demonstrate that three different branches of the MAP kinase signaling pathway with overlapping consequences are involved in the pathogenesis of cardiomyopathy caused by LMNA mutations. They further suggest that pharmacological inhibition of p38α may be useful in the treatment of this disease.
Assuntos
Cardiomiopatia Dilatada/enzimologia , Etilenodiaminas/farmacologia , Indazóis/farmacologia , Lamina Tipo A/genética , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Mutação de Sentido Incorreto , Transdução de Sinais , Adolescente , Animais , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/metabolismo , Células Cultivadas , Feminino , Humanos , Lamina Tipo A/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Proteína Quinase 14 Ativada por Mitógeno/genética , Miócitos Cardíacos/enzimologia , Miócitos Cardíacos/metabolismo , Adulto JovemRESUMO
BACKGROUND: Mutations in the LMNA gene encoding A-type nuclear lamins can cause dilated cardiomyopathy with or without skeletal muscular dystrophy. Previous studies have shown abnormally increased extracellular signal-regulated kinase 1/2 activity in hearts of Lmna(H222P/H222P) mice, a small animal model. Inhibition of this abnormal signaling activity with a mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor has beneficial effects on heart function and survival in these mice. However, such treatment has not been examined relative to any standard of care intervention for dilated cardiomyopathy or heart failure. We therefore examined the effects of an angiotensin II converting enzyme (ACE) inhibitor on left ventricular function in Lmna(H222P/H222P) mice and assessed if adding a MEK1/2 inhibitor would provide added benefit. METHODS: Male Lmna(H222P/H222P) mice were treated with the ACE inhibitor benazepril, the MEK1/2 inhibitor selumetinib or both. Transthoracic echocardiography was used to measure left ventricular diameters and fractional shortening was calculated. RESULTS: Treatment of Lmna(H222P/H222P) mice with either benazepril or selumetinib started at 8weeks of age, before the onset of detectable left ventricular dysfunction, lead to statistically significantly increased fractional shortening compared to placebo at 16weeks of age. There was a trend towards a great value for fractional shortening in the selumetinib-treated mice. When treatment was started at 16weeks of age, after the onset of left ventricular dysfunction, the addition of selumetinib treatment to benazepril lead to a statistically significant increase in left ventricular fractional shortening at 20weeks of age. CONCLUSIONS: Both ACE inhibition and MEK1/2 inhibition have beneficial effects on left ventricular function in Lmna(H222P/H222P) mice and both drugs together have a synergistic benefit when initiated after the onset of left ventricular dysfunction. These results provide further preclinical rationale for a clinical trial of a MEK1/2 inhibitor in addition to standard of care in patients with dilated cardiomyopathy caused by LMNA mutations.
Assuntos
Angiotensina II/metabolismo , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Cardiomiopatia Dilatada/tratamento farmacológico , Cardiomiopatia Dilatada/fisiopatologia , Lamina Tipo A/genética , MAP Quinase Quinase 1/antagonistas & inibidores , MAP Quinase Quinase 2/antagonistas & inibidores , Animais , Benzazepinas , Benzimidazóis , Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/patologia , Masculino , Camundongos , Mutação/genética , Resultado do TratamentoRESUMO
BACKGROUND: Mutations in LMNA gene cause cardiomyopathy, for which mechanistic insights are lacking. RESULTS: Dusp4 expression is enhanced in hearts with LMNA cardiomyopathy, and its overexpression in mice causes it by activating AKT-mTOR signaling that impairs autophagy. CONCLUSIONS: Dusp4 causes cardiac dysfunction and may contribute to the development of LMNA cardiomyopathy. SIGNIFICANCE: Revealing pathogenic mechanisms of LMNA cardiomyopathy is essential for the development of mechanism-based therapies. Mutations in the lamin A/C gene (LMNA) cause a diverse spectrum of diseases, the most common of which is dilated cardiomyopathy often with skeletal muscular dystrophy. Lamin A and C are fundamental components of the nuclear lamina, a dynamic meshwork of intermediate filaments lining the nuclear envelope inner membrane. Prevailing evidence suggests that the nuclear envelope functions as a signaling node and that abnormality in the nuclear lamina leads to dysregulated signaling pathways that underlie disease pathogenesis. We previously showed that activated ERK1/2 in hearts of a mouse model of LMNA cardiomyopathy (Lmna(H222P/H222P) mice) contributes to disease, but the complete molecular pathogenesis remains poorly understood. Here we uncover a pathogenic role of dual specificity phosphatase 4 (Dusp4), which is transcriptionally induced by ERK1/2. Dusp4 is highly expressed in the hearts of Lmna(H222P/H222P) mice, and transgenic mice with cardiac-selective overexpression of Dusp4 display heart dysfunction similar to LMNA cardiomyopathy. In both primary tissue and cell culture models, overexpression of Dusp4 positively regulates AKT-mTOR signaling, resulting in impaired autophagy. These findings identify a pathogenic role of Dusp4 in LMNA cardiomyopathy.