RESUMO
BACKGROUND: Inflammatory and metabolic biomarkers have been associated with hepatocellular cancer (HCC) risk in phases I and II biomarker studies. We developed and internally validated a robust metabolic biomarker panel predictive of HCC in a longitudinal phase III study. METHODS: We used data and banked serum from a prospective cohort of 2266 adult patients with cirrhosis who were followed until the development of HCC (n=126). We custom designed a FirePlex immunoassay to measure baseline serum levels of 39 biomarkers and established a set of biomarkers with the highest discriminatory ability for HCC. We performed bootstrapping to evaluate the predictive performance using C-index and time-dependent area under the receiver operating characteristic curve (AUROC). We quantified the incremental predictive value of the biomarker panel when added to previously validated clinical models. RESULTS: We identified a nine-biomarker panel (P9) with a C-index of 0.67 (95% CI 0.66 to 0.67), including insulin growth factor-1, interleukin-10, transforming growth factor ß1, adipsin, fetuin-A, interleukin-1 ß, macrophage stimulating protein α chain, serum amyloid A and TNF-α. Adding P9 to our clinical model with 10 factors including AFP improved AUROC at 1 and 2 years by 4.8% and 2.7%, respectively. Adding P9 to aMAP score improved AUROC at 1 and 2 years by 14.2% and 7.6%, respectively. Adding AFP L-3 or DCP did not change the predictive ability of the P9 model. CONCLUSIONS: We identified a panel of nine serum biomarkers that is independently associated with developing HCC in cirrhosis and that improved the predictive ability of risk stratification models containing clinical factors.
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BACKGROUND: The progression of atrial fibrillation (AF) from paroxysmal to persistent forms remains a major clinical challenge. Abnormal sarcoplasmic reticulum (SR) Ca(2+) leak via the ryanodine receptor type 2 (RyR2) has been observed as a source of ectopic activity in various AF models. However, its potential role in progression to long-lasting spontaneous AF (sAF) has never been tested. This study was designed to test the hypothesis that enhanced RyR2-mediated Ca(2+) release underlies the development of a substrate for sAF and to elucidate the underlying mechanisms. METHODS AND RESULTS: CREM-IbΔC-X transgenic (CREM) mice developed age-dependent progression from spontaneous atrial ectopy to paroxysmal and eventually long-lasting AF. The development of sAF in CREM mice was preceded by enhanced diastolic Ca(2+) release, atrial enlargement, and marked conduction abnormalities. Genetic inhibition of Ca(2+)/calmodulin-dependent protein kinase II-mediated RyR2-S2814 phosphorylation in CREM mice normalized open probability of RyR2 channels and SR Ca(2+) release, delayed the development of spontaneous atrial ectopy, fully prevented sAF, suppressed atrial dilation, and forestalled atrial conduction abnormalities. Hyperactive RyR2 channels directly stimulated the Ca(2+)-dependent hypertrophic pathway nuclear factor of activated T cell/Rcan1-4, suggesting a role for the nuclear factor of activated T cell/Rcan1-4 system in the development of a substrate for long-lasting AF in CREM mice. CONCLUSIONS: RyR2-mediated SR Ca(2+) leak directly underlies the development of a substrate for sAF in CREM mice, the first demonstration of a molecular mechanism underlying AF progression and sAF substrate development in an experimental model. Our work demonstrates that the role of abnormal diastolic Ca(2+) release in AF may not be restricted to the generation of atrial ectopy but extends to the development of atrial remodeling underlying the AF substrate.
Assuntos
Fibrilação Atrial/metabolismo , Cálcio/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/metabolismo , Fatores Etários , Animais , Fibrilação Atrial/genética , Fibrilação Atrial/fisiopatologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Feminino , Sistema de Condução Cardíaco/metabolismo , Sistema de Condução Cardíaco/fisiopatologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Miócitos Cardíacos/metabolismoRESUMO
Voltage-gated Kv1.1 channels encoded by the Kcna1 gene are traditionally regarded as being neural-specific with no known expression or intrinsic functional role in the heart. However, recent studies in mice reveal low-level Kv1.1 expression in heart and cardiac abnormalities associated with Kv1.1-deficiency suggesting that the channel may have a previously unrecognized cardiac role. Therefore, this study tests the hypothesis that Kv1.1 channels are associated with arrhythmogenesis and contribute to intrinsic cardiac function. In intra-atrial burst pacing experiments, Kcna1-null mice exhibited increased susceptibility to atrial fibrillation (AF). The atria of Kcna1-null mice showed minimal Kv1 family ion channel remodeling and fibrosis as measured by qRT-PCR and Masson's trichrome histology, respectively. Using RT-PCR, immunocytochemistry, and immunoblotting, KCNA1 mRNA and protein were detected in isolated mouse cardiomyocytes and human atria for the first time. Patients with chronic AF (cAF) showed no changes in KCNA1 mRNA levels relative to controls; however, they exhibited increases in atrial Kv1.1 protein levels, not seen in paroxysmal AF patients. Patch-clamp recordings of isolated human atrial myocytes revealed significant dendrotoxin-K (DTX-K)-sensitive outward current components that were significantly increased in cAF patients, reflecting a contribution by Kv1.1 channels. The concomitant increases in Kv1.1 protein and DTX-K-sensitive currents in atria of cAF patients suggest that the channel contributes to the pathological mechanisms of persistent AF. These findings provide evidence of an intrinsic cardiac role of Kv1.1 channels and indicate that they may contribute to atrial repolarization and AF susceptibility.
Assuntos
Fibrilação Atrial/metabolismo , Átrios do Coração/metabolismo , Canal de Potássio Kv1.1/metabolismo , Idoso , Animais , Feminino , Humanos , Immunoblotting , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Miócitos Cardíacos/metabolismo , Técnicas de Patch-Clamp , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Ca(2+)-calmodulin kinase II (CaMKII) activation is deleterious in cardiac ischemia/reperfusion (I/R). Moreover, inhibition of CaMKII-dependent phosphorylations at the sarcoplasmic reticulum (SR) prevents CaMKII-induced I/R damage. However, the downstream targets of CaMKII at the SR level, responsible for this detrimental effect, remain unclear. In the present study we aimed to dissect the role of the two main substrates of CaMKII at the SR level, phospholamban (PLN) and ryanodine receptors (RyR2), in CaMKII-dependent I/R injury. In mouse hearts subjected to global I/R (45/120min), phosphorylation of the primary CaMKII sites, S2814 on cardiac RyR2 and of T17 on PLN, significantly increased at the onset of reperfusion whereas PKA-dependent phosphorylation of RyR2 and PLN did not change. Similar results were obtained in vivo, in mice subjected to regional myocardial I/R (1/24h). Knock-in mice with an inactivated serine 2814 phosphorylation site on RyR2 (S2814A) significantly improved post-ischemic mechanical recovery, reduced infarct size and decreased apoptosis. Conversely, knock-in mice, in which CaMKII site of RyR2 is constitutively activated (S2814D), significantly increased infarct size and exacerbated apoptosis. In S2814A and S2814D mice subjected to regional myocardial ischemia, infarct size was also decreased and increased respectively. Transgenic mice with double-mutant non-phosphorylatable PLN (S16A/T17A) in the PLN knockout background (PLNDM) also showed significantly increased post-ischemic cardiac damage. This effect cannot be attributed to PKA-dependent PLN phosphorylation and was not due to the enhanced L-type Ca(2+) current, present in these mice. Our results reveal a major role for the phosphorylation of S2814 site on RyR2 in CaMKII-dependent I/R cardiac damage. In contrast, they showed that CaMKII-dependent increase in PLN phosphorylation during reperfusion opposes rather than contributes to I/R damage.
Assuntos
Proteínas de Ligação ao Cálcio/genética , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Cálcio/metabolismo , Traumatismo por Reperfusão Miocárdica/genética , Miócitos Cardíacos/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Animais , Sinalização do Cálcio , Proteínas de Ligação ao Cálcio/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Morte Celular , Regulação da Expressão Gênica , Técnicas de Introdução de Genes , Ventrículos do Coração/citologia , Ventrículos do Coração/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Mutação , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Miócitos Cardíacos/citologia , Técnicas de Cultura de Órgãos , Fosforilação , Cultura Primária de Células , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Retículo Sarcoplasmático/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismoRESUMO
UCP3's exact physiological function in lipid handling in skeletal and cardiac muscle remains unknown. Interestingly, etomoxir, a fat oxidation inhibitor and strong inducer of UCP3, is proposed for treating both diabetes and heart failure. We hypothesize that the upregulation of UCP3 upon etomoxir serves to protect mitochondria against lipotoxicity. To evaluate UCP3's role in skeletal muscle (skm) and heart under lipid-challenged conditions, the effect of UCP3 ablation was examined in a state of dysbalance between fat availability and oxidative capacity. Wild type (WT) and UCP3(-/-) mice were subjected to high-fat feeding for 14 days. From day 6 onwards, they were given either saline or etomoxir. Etomoxir treatment induced an increase in markers of lipotoxicity in skm compared to saline. This increase upon etomoxir was similar for both, WT and UCP3(-/-) mice, suggesting that UCP3 does not play a role in protection against lipotoxicity. Interestingly, we observed 25 % mortality in UCP3(-/-)s upon etomoxir administration vs. 11 % in WTs. This increased mortality in UCP3(-/-) compared to WT mice could not be explained by differences in cardiac lipotoxicity, apoptosis, fibrosis (histology, immunohistochemistry), oxidative capacity (respirometry) or function (echocardiography). Electrophysiology demonstrated, however, prolonged QRS and QTc intervals and greater susceptibility to ventricular tachycardia upon programmed electrical stimulation in etomoxir-treated UCP3(-/-)s versus WTs. Isoproterenol administration after pacing resulted in 75 % mortality in UCP3(-/-)s vs. 14 % in WTs. Our results argue against a protective role for UCP3 on skm metabolism under lipid overload, but suggest UCP3 to be crucial in prevention of arrhythmias upon lipid-challenged conditions.
Assuntos
Morte Súbita Cardíaca/etiologia , Canais Iônicos/fisiologia , Mitocôndrias Musculares/fisiologia , Proteínas Mitocondriais/fisiologia , Animais , Canais Iônicos/deficiência , Lipídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias Musculares/metabolismo , Proteínas Mitocondriais/deficiência , Músculo Esquelético/ultraestrutura , Oxirredução , Proteína Desacopladora 3RESUMO
RATIONALE: Increased activity of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is thought to promote heart failure (HF) progression. However, the importance of CaMKII phosphorylation of ryanodine receptors (RyR2) in HF development and associated diastolic sarcoplasmic reticulum Ca(2+) leak is unclear. OBJECTIVE: Determine the role of CaMKII phosphorylation of RyR2 in patients and mice with nonischemic and ischemic forms of HF. METHODS AND RESULTS: Phosphorylation of the primary CaMKII site S2814 on RyR2 was increased in patients with nonischemic, but not with ischemic, HF. Knock-in mice with an inactivated S2814 phosphorylation site were relatively protected from HF development after transverse aortic constriction compared with wild-type littermates. After transverse aortic constriction, S2814A mice did not exhibit pulmonary congestion and had reduced levels of atrial natriuretic factor. Cardiomyocytes from S2814A mice exhibited significantly lower sarcoplasmic reticulum Ca(2+) leak and improved sarcoplasmic reticulum Ca(2+) loading compared with wild-type mice after transverse aortic constriction. Interestingly, these protective effects on cardiac contractility were not observed in S2814A mice after experimental myocardial infarction. CONCLUSIONS: Our results suggest that increased CaMKII phosphorylation of RyR2 plays a role in the development of pathological sarcoplasmic reticulum Ca(2+) leak and HF development in nonischemic forms of HF such as transverse aortic constriction in mice.
Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Insuficiência Cardíaca/metabolismo , Miocárdio/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Adulto , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/antagonistas & inibidores , Cardiomegalia/etiologia , Cardiomegalia/metabolismo , Cardiomiopatia Dilatada/complicações , Cardiomiopatia Dilatada/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Feminino , Técnicas de Introdução de Genes , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/prevenção & controle , Humanos , Imageamento por Ressonância Magnética , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Mutação , Contração Miocárdica , Isquemia Miocárdica/complicações , Isquemia Miocárdica/metabolismo , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Retículo Sarcoplasmático/metabolismo , Serina , Fatores de Tempo , Regulação para Cima , Função Ventricular Esquerda , Pressão Ventricular , Remodelação VentricularRESUMO
Aberrant intracellular Ca(2+) regulation is believed to contribute to the development of cardiomyopathy in Duchenne muscular dystrophy. Here, we tested whether inhibition of protein kinase A (PKA) phosphorylation of ryanodine receptor type 2 (RyR2) prevents dystrophic cardiomyopathy by reducing SR Ca(2+) leak in the mdx mouse model of Duchenne muscular dystrophy. mdx mice were crossed with RyR2-S2808A mice, in which PKA phosphorylation site S2808 on RyR2 is inactivated by alanine substitution. Compared with mdx mice that developed age-dependent heart failure, mdx-S2808A mice exhibited improved fractional shortening and reduced cardiac dilation. Whereas application of isoproterenol severely depressed cardiac contractility and caused 95% mortality in mdx mice, contractility was preserved with only 19% mortality in mdx-S2808A mice. SR Ca(2+) leak was greater in ventricular myocytes from mdx than mdx-S2808A mice. Myocytes from mdx mice had a higher incidence of isoproterenol-induced diastolic Ca(2+) release events than myocytes from mdx-S2808A mice. Thus, inhibition of PKA phosphorylation of RyR2 reduced SR Ca(2+) leak and attenuated cardiomyopathy in mdx mice, suggesting that enhanced PKA phosphorylation of RyR2 at S2808 contributes to abnormal Ca(2+) homeostasis associated with dystrophic cardiomyopathy.
Assuntos
Cardiomiopatias/prevenção & controle , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Envelhecimento/patologia , Animais , Cálcio/metabolismo , Cardiomiopatias/complicações , Cardiomiopatias/enzimologia , Cardiomiopatias/patologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Morte Súbita/prevenção & controle , Fibrose , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/prevenção & controle , Espaço Intracelular/metabolismo , Isoproterenol , Camundongos , Camundongos Endogâmicos mdx , Mutação/genética , Miocárdio/metabolismo , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Fosforilação , Fosfosserina/metabolismo , Sarcolema/metabolismo , Sarcolema/patologiaRESUMO
BACKGROUND: Excitation-contraction coupling in striated muscle requires proper communication of plasmalemmal voltage-activated Ca2+ channels and Ca2+ release channels on sarcoplasmic reticulum within junctional membrane complexes. Although previous studies revealed a loss of junctional membrane complexes and embryonic lethality in germ-line junctophilin-2 (JPH2) knockout mice, it has remained unclear whether JPH2 plays an essential role in junctional membrane complex formation and the Ca(2+)-induced Ca(2+) release process in the heart. Our recent work demonstrated loss-of-function mutations in JPH2 in patients with hypertrophic cardiomyopathy. METHODS AND RESULTS: To elucidate the role of JPH2 in the heart, we developed a novel approach to conditionally reduce JPH2 protein levels using RNA interference. Cardiac-specific JPH2 knockdown resulted in impaired cardiac contractility, which caused heart failure and increased mortality. JPH2 deficiency resulted in loss of excitation-contraction coupling gain, precipitated by a reduction in the number of junctional membrane complexes and increased variability in the plasmalemma-sarcoplasmic reticulum distance. CONCLUSIONS: Loss of JPH2 had profound effects on Ca2+ release channel inactivation, suggesting a novel functional role for JPH2 in regulating intracellular Ca2+ release channels in cardiac myocytes. Thus, our novel approach of cardiac-specific short hairpin RNA-mediated knockdown of junctophilin-2 has uncovered a critical role for junctophilin in intracellular Ca2+ release in the heart.
Assuntos
Membrana Celular/metabolismo , Junções Intercelulares/metabolismo , Proteínas de Membrana/deficiência , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Animais , Canais de Cálcio/deficiência , Canais de Cálcio/genética , Canais de Cálcio/metabolismo , Membrana Celular/genética , Membrana Celular/ultraestrutura , Técnicas de Silenciamento de Genes/métodos , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/mortalidade , Insuficiência Cardíaca/patologia , Junções Intercelulares/genética , Junções Intercelulares/ultraestrutura , Proteínas de Membrana/genética , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Contração Miocárdica/genética , RNA Interferente Pequeno/genética , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Canal de Liberação de Cálcio do Receptor de Rianodina/ultraestruturaRESUMO
African-American (AA) men are more likely to be diagnosed with and die from prostate cancer than European American (EA) men. Despite the central role of the androgen receptor (AR) transcription factor in prostate cancer, little is known about the contribution of epigenetics to observed racial disparities. We performed AR chromatin immunoprecipitation sequencing on primary prostate tumors from AA and EA men, finding that sites with greater AR binding intensity in AA relative to EA prostate cancer are enriched for lipid metabolism and immune response genes. Integration with transcriptomic and metabolomic data demonstrated coinciding upregulation of lipid metabolism gene expression and increased lipid levels in AA prostate cancer. In a metastatic prostate cancer cohort, upregulated lipid metabolism associated with poor prognosis. These findings offer the first insights into ancestry-specific differences in the prostate cancer AR cistrome. The data suggest a model whereby increased androgen signaling may contribute to higher levels of lipid metabolism, immune response, and cytokine signaling in AA prostate tumors. Given the association of upregulated lipogenesis with prostate cancer progression, our study provides a plausible biological explanation for the higher incidence and aggressiveness of prostate cancer observed in AA men. SIGNIFICANCE: With immunotherapies and inhibitors of metabolic enzymes in clinical development, the altered lipid metabolism and immune response in African-American men provides potential therapeutic opportunities to attenuate racial disparities in prostate cancer.
Assuntos
Neoplasias da Próstata , Receptores Androgênicos , Negro ou Afro-Americano/genética , Humanos , Imunidade , Metabolismo dos Lipídeos/genética , Masculino , Neoplasias da Próstata/patologia , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Regulação para CimaRESUMO
BACKGROUND: approximately half of patients with heart failure die suddenly as a result of ventricular arrhythmias. Although abnormal Ca(2+) release from the sarcoplasmic reticulum through ryanodine receptors (RyR2) has been linked to arrhythmogenesis, the molecular mechanisms triggering release of arrhythmogenic Ca(2+) remain unknown. We tested the hypothesis that increased RyR2 phosphorylation by Ca(2+)/calmodulin-dependent protein kinase II is both necessary and sufficient to promote lethal ventricular arrhythmias. METHODS AND RESULTS: mice in which the S2814 Ca(2+)/calmodulin-dependent protein kinase II site on RyR2 is constitutively activated (S2814D) develop pathological sarcoplasmic reticulum Ca(2+) release events, resulting in reduced sarcoplasmic reticulum Ca(2+) load on confocal microscopy. These Ca(2+) release events are associated with increased RyR2 open probability in lipid bilayer preparations. At baseline, young S2814D mice have structurally and functionally normal hearts without arrhythmias; however, they develop sustained ventricular tachycardia and sudden cardiac death on catecholaminergic provocation by caffeine/epinephrine or programmed electric stimulation. Young S2814D mice have a significant predisposition to sudden arrhythmogenic death after transverse aortic constriction surgery. Finally, genetic ablation of the Ca(2+)/calmodulin-dependent protein kinase II site on RyR2 (S2814A) protects mutant mice from pacing-induced arrhythmias versus wild-type mice after transverse aortic constriction surgery. CONCLUSIONS: our results suggest that Ca(2+)/calmodulin-dependent protein kinase II phosphorylation of RyR2 Ca(2+) release channels at S2814 plays an important role in arrhythmogenesis and sudden cardiac death in mice with heart failure.
Assuntos
Arritmias Cardíacas/epidemiologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Insuficiência Cardíaca/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Taquicardia Ventricular/epidemiologia , Animais , Arritmias Cardíacas/metabolismo , Cálcio/metabolismo , Morte Súbita Cardíaca/epidemiologia , Estimulação Elétrica , Camundongos , Camundongos Transgênicos , Modelos Animais , Fosforilação , Fatores de Risco , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Retículo Sarcoplasmático/metabolismo , Taquicardia Ventricular/metabolismoRESUMO
Castration-resistant prostate cancer (CRPC) remains highly lethal and in need of novel, actionable therapeutic targets. The pioneer factor GATA2 is a significant prostate cancer (PC) driver and is linked to poor prognosis. GATA2 directly promotes androgen receptor (AR) gene expression (both full-length and splice-variant) and facilitates AR binding to chromatin, recruitment of coregulators, and target gene transcription. Unfortunately, there is no clinically applicable GATA2 inhibitor available at the moment. Using a bioinformatics algorithm, we screened in silico 2650 clinically relevant drugs for a potential GATA2 inhibitor. Validation studies used cytotoxicity and proliferation assays, global gene expression analysis, RT-qPCR, reporter assay, reverse phase protein array analysis (RPPA), and immunoblotting. We examined target engagement via cellular thermal shift assay (CETSA), ChIP-qPCR, and GATA2 DNA-binding assay. We identified the vasodilator dilazep as a potential GATA2 inhibitor and confirmed on-target activity via CETSA. Dilazep exerted anticancer activity across a broad panel of GATA2-dependent PC cell lines in vitro and in a PDX model in vivo. Dilazep inhibited GATA2 recruitment to chromatin and suppressed the cell-cycle program, transcriptional programs driven by GATA2, AR, and c-MYC, and the expression of several oncogenic drivers, including AR, c-MYC, FOXM1, CENPF, EZH2, UBE2C, and RRM2, as well as of several mediators of metastasis, DNA damage repair, and stemness. In conclusion, we provide, via an extensive compendium of methodologies, proof-of-principle that a small molecule can inhibit GATA2 function and suppress its downstream AR, c-MYC, and other PC-driving effectors. We propose GATA2 as a therapeutic target in CRPC.
Assuntos
Neoplasias de Próstata Resistentes à Castração , Linhagem Celular Tumoral , Cromatina , Dilazep/uso terapêutico , Fator de Transcrição GATA2/genética , Fator de Transcrição GATA2/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Oncogenes , Neoplasias de Próstata Resistentes à Castração/genética , Receptores Androgênicos/metabolismoRESUMO
Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood. Improving the management of rhabdomyosarcoma requires a better understanding of growth regulation. Patched haploinsufficient (Ptch+/-) mice spontaneously develop soft tissue sarcomas that resemble human rhabdomyosarcomas. Using microarray profiling and quantitative real-time reverse transcriptase polymerase chain reaction, we identified candidate genes differentially expressed in Ptch+/- mouse rhabdomyosarcoma relative to mature muscle. Overexpressed genes include Secreted Phosphoprotein 1 (Spp1, Osteopontin), and Matrix Metalloproteinases-2 and -14 (Mmp2 and Mmp14). Spp1 is an integrin-binding phosphoglycoprotein upregulated in carcinomas, and Mmps regulate tumour invasion. Immunochemical analyses of murine and human rhabdomyosarcoma specimens confirmed increased expression of Spp1, Mmp2, Mmp14, nuclear factor-kappa B (NF-kappaB) p65 and its phosphorylated active isoform. Neutralising Spp1 antibody decreased Mmp14 RNA in murine rhabdomyosarcoma cultures, indicating a positive regulatory role for extracellular Spp1. Plasma from rhabdomyosarcoma patients display elevated levels of SPP1. These results implicate Spp1, NF-kappaB, and Mmp activation as a putative signalling pathway involved in rhabdomyosarcoma growth.
Assuntos
Metaloproteinases da Matriz/metabolismo , Proteínas de Neoplasias/metabolismo , Osteopontina/metabolismo , Rabdomiossarcoma/metabolismo , Animais , Western Blotting , DNA Complementar/metabolismo , Ensaio de Imunoadsorção Enzimática , Expressão Gênica , Heterozigoto , Humanos , Imuno-Histoquímica , Metaloproteinases da Matriz/genética , Camundongos , Análise em Microsséries , Mutação/genética , Proteínas de Neoplasias/genética , Osteopontina/genética , RNA Neoplásico/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Rabdomiossarcoma/genéticaRESUMO
BACKGROUND: Medulloblastoma is the most common malignant brain tumor of childhood. Children who relapse usually die of their disease, which reflects resistance to radiation and/or chemotherapy. Improvements in outcome require a better understanding of the molecular basis of medulloblastoma growth and treatment response. TP73 is a member of the TP53 tumor suppressor gene family that has been found to be overexpressed in a variety of tumors and mediates apoptotic responses to genotoxic stress. In this study, we assessed expression of TP73 RNA species in patient tumor specimens and in medulloblastoma cell lines, and manipulated expression of full-length TAp73 and amino-terminal truncated DeltaNp73 to assess their effects on growth. METHODS: We analyzed medulloblastoma samples from thirty-four pediatric patients and the established medulloblastoma cell lines, Daoy and D283MED, for expression of TP73 RNA including the full-length transcript and the 5'-terminal variants that encode the DeltaNp73 isoform, as well as TP53 RNA using quantitative real time-RTPCR. Protein expression of TAp73 and DeltaNp73 was quantitated with immunoblotting methods. Clinical outcome was analyzed based on TP73 RNA and p53 protein expression. To determine effects of overexpression or knock-down of TAp73 and DeltaNp73 on cell cycle and apoptosis, we analyzed transiently transfected medulloblastoma cell lines with flow cytometric and TUNEL methods. RESULTS: Patient medulloblastoma samples and cell lines expressed full-length and 5'-terminal variant TP73 RNA species in 100-fold excess compared to non-neoplastic brain controls. Western immunoblot analysis confirmed their elevated levels of TAp73 and amino-terminal truncated DeltaNp73 proteins. Kaplan-Meier analysis revealed trends toward favorable overall and progression-free survival of patients whose tumors display TAp73 RNA overexpression. Overexpression of TAp73 or DeltaNp73 induced apoptosis under basal growth conditions in vitro and sensitized them to cell death in response to chemotherapeutic agents. CONCLUSION: These results indicate that primary medulloblastomas express significant levels of TP73 isoforms, and suggest that they can modulate the survival and genotoxic responsiveness of medulloblastomas cells.
Assuntos
Apoptose/genética , Neoplasias Cerebelares/genética , Proteínas de Ligação a DNA/genética , Regulação Neoplásica da Expressão Gênica , Meduloblastoma/genética , Proteínas Nucleares/genética , RNA Neoplásico/genética , Proteínas Supressoras de Tumor/genética , Biomarcadores Tumorais/genética , Western Blotting , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Neoplasias Cerebelares/metabolismo , Neoplasias Cerebelares/patologia , Criança , Pré-Escolar , Progressão da Doença , Citometria de Fluxo , Seguimentos , Inativação Gênica , Humanos , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Lactente , Masculino , Meduloblastoma/metabolismo , Meduloblastoma/patologia , Prognóstico , Estudos Retrospectivos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Índice de Gravidade de Doença , Fatores de TempoRESUMO
BACKGROUND: Hypertrophic cardiomyopathy (HCM), defined as asymmetric left ventricular hypertrophy, is a leading cause of cardiac death in the young. Perturbations in calcium (Ca2+) handling proteins have been implicated in the pathogenesis of HCM. JPH2-encoded junctophilin 2 is a major component of the junctional membrane complex, the subcellular microdomain involved in excitation-contraction coupling. We hypothesized that a novel JPH2 mutation identified in patients with HCM is causally linked to HCM, and alters intracellular Ca2+ signaling in a pro-hypertrophic manner. OBJECTIVES: To determine using a transgenic mouse model whether a JPH2 mutation found in a HCM patient is responsible for disease development. METHODS: Genetic interrogation of a large cohort of HCM cases was conducted for all coding exons of JPH2. Pseudo-knock-in (PKI) mice containing a novel JPH2 variant were subjected to echocardiography, cardiac MRI, hemodynamic analysis, and histology. RESULTS: A novel JPH2 mutation, A405S, was identified in a genotype-negative proband with significant basal septal hypertrophy. Although initially underappreciated by traditional echocardiographic imaging, PKI mice with this JPH2 mutation (residue A399S in mice) were found to exhibit similar basal hypertrophy using a newly developed echo imaging plane, and this was confirmed using cardiac MRI. Histological analysis demonstrated cardiomyocyte hypertrophy and disarray consistent with HCM. CONCLUSIONS: Variant A405S is a novel HCM-associated mutation in JPH2 found in a proband negative for mutations in the canonical HCM-associated genes. Studies in the analogous mouse model demonstrated for the first time a causal link between a JPH2 defect and HCM. Moreover, novel imaging approaches identified subvalvular septal hypertrophy, specific findings also reported in the human JPH2 mutation carrier.
RESUMO
BACKGROUND: Long-term exposure to microgravity during space flight may lead to cardiac remodeling and rhythm disturbances. In mice, hindlimb unloading (HU) mimics the effects of microgravity and stimulates physiological adaptations, including cardiovascular deconditioning. Recent studies have demonstrated an important role played by changes in intracellular Ca handling in the pathogenesis of heart failure and arrhythmia. In this study, we tested the hypothesis that cardiac remodeling following HU in mice involves abnormal intracellular Ca regulation through the cardiac ryanodine receptor (RyR2). METHODS AND RESULTS: Mice were subjected to HU by tail suspension for 28 to 56 days in order to induce cardiac remodeling (n=15). Control mice (n=19) were treated equally, with the exception of tail suspension. Echocardiography revealed cardiac enlargement and depressed contractility starting at 28 days post-HU versus control. Moreover, mice were more susceptible to pacing-induced ventricular arrhythmias after HU. Ventricular myocytes isolated from HU mice exhibited an increased frequency of spontaneous sarcoplasmic reticulum (SR) Ca release events and enhanced SR Ca leak via RyR2. Western blotting revealed increased RyR2 phosphorylation at S2814, and increased CaMKII auto-phosphorylation at T287, suggesting that CaMKII activation of RyR2 might underlie enhanced SR Ca release in HU mice. CONCLUSION: These data suggest that abnormal intracellular Ca handling, likely due to increased CaMKII phosphorylation of RyR2, plays a role in cardiac remodeling following simulated microgravity in mice.
Assuntos
Arritmias Cardíacas/etiologia , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Simulação de Ausência de Peso/efeitos adversos , Animais , Arritmias Cardíacas/metabolismo , Cálcio/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Modelos Animais de Doenças , Elevação dos Membros Posteriores , Camundongos , Fosforilação/fisiologia , Retículo Sarcoplasmático/metabolismo , Fatores de Tempo , Remodelação Ventricular/fisiologiaRESUMO
AIMS: Altered Ca(2+) handling in atrial fibrillation (AF) has been associated with dysregulated protein phosphatase 1 (PP1) and subcellular heterogeneities in protein phosphorylation, but the underlying mechanisms remain unclear. This is due to a lack of investigation into the local, rather than global, regulation of PP1 on different subcellular targets such as ryanodine receptor type 2 (RyR2), especially in AF. METHODS AND RESULTS: We tested the hypothesis that impaired local regulation of PP1 causes RyR2 hyperphosphorylation thereby promoting AF susceptibility. To specifically disrupt PP1's local regulation of RyR2, we used the spinophilin knockout (Sp(-/-)) mice (Mus musculus) since PP1 is targeted to RyR2 via spinophilin. Without spinophilin, the interaction between PP1 and RyR2 was reduced by 64%, while RyR2 phosphorylation was increased by 43% at serine (S)2814 but unchanged at S2808. Lipid bilayer experiments revealed that single RyR2 channels isolated from Sp(-/-) hearts had an increased open probability. Likewise, Ca(2+) spark frequency normalized to sarcoplasmic reticulum Ca(2+) content was also enhanced in Sp(-/-) atrial myocytes, but normalized by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibitors KN-93 and AIP and also by genetic inhibition of RyR2 S2814 phosphorylation. Finally, Sp(-/-) mice exhibited increased atrial ectopy and susceptibility to pacing-induced AF, both of which were also prevented by the RyR2 S2814A mutation. CONCLUSION: PP1 regulates RyR2 locally by counteracting CaMKII phosphorylation of RyR2. Decreased local PP1 regulation of RyR2 contributes to RyR2 hyperactivity and promotes AF susceptibility. This represents a novel mechanism for subcellular modulation of calcium channels and may represent a potential drug target of AF.
Assuntos
Fibrilação Atrial/etiologia , Fibrilação Atrial/metabolismo , Proteína Fosfatase 1/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Substituição de Aminoácidos , Animais , Fibrilação Atrial/genética , Sinalização do Cálcio , Modelos Animais de Doenças , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Mutantes , Proteínas dos Microfilamentos/deficiência , Proteínas dos Microfilamentos/genética , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Miocárdio/metabolismo , Proteínas do Tecido Nervoso/deficiência , Proteínas do Tecido Nervoso/genética , Fosforilação , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Retículo Sarcoplasmático/metabolismoRESUMO
AIMS: Transverse tubules (TTs) provide the basic subcellular structures that facilitate excitation-contraction (EC) coupling, the essential process that underlies normal cardiac contractility. Previous studies have shown that TTs develop within the first few weeks of life in mammals but the molecular determinants of this development have remained elusive. This study aims to elucidate the role of junctophilin-2 (JPH2), a junctional membrane complex protein, in the maturation of TTs in cardiomyocytes. METHODS AND RESULTS: Using a novel cardiac-specific short-hairpin-RNA-mediated JPH2 knockdown mouse model (Mus musculus; αMHC-shJPH2), we assessed the effects of the loss of JPH2 on the maturation of the ventricular TT structure. Between embryonic day (E) 10.5 and postnatal day (P) 10, JPH2 mRNA and protein levels were reduced by >70% in αMHC-shJPH2 mice. At P8 and P10, knockdown of JPH2 significantly inhibited the maturation of TTs, while expression levels of other genes implicated in TT development remained mostly unchanged. At the same time, intracellular Ca(2+) handling was disrupted in ventricular myocytes from αMHC- shJPH2 mice, which developed heart failure by P10 marked by reduced ejection fraction, ventricular dilation, and premature death. In contrast, JPH2 transgenic mice exhibited accelerated TT maturation by P8. CONCLUSION: Our findings suggest that JPH2 is necessary for TT maturation during postnatal cardiac development in mice. In particular, JPH2 may be critical in anchoring the invaginating sarcolemma to the sarcoplasmic reticulum, thereby enabling the maturation of the TT network.
Assuntos
Coração/embriologia , Proteínas de Membrana/fisiologia , Miócitos Cardíacos/citologia , Sarcolema/fisiologia , Animais , Cálcio/metabolismo , Coração/crescimento & desenvolvimento , Insuficiência Cardíaca/etiologia , Camundongos , Camundongos Endogâmicos C57BL , RNA Interferente Pequeno/genéticaRESUMO
In response to chronic hypertension, the heart compensates by hypertrophic growth, which frequently progresses to heart failure. Although intracellular calcium (Ca(2+)) has a central role in hypertrophic signaling pathways, the Ca(2+) source for activating these pathways remains elusive. We hypothesized that pathological sarcoplasmic reticulum Ca(2+) leak through defective cardiac intracellular Ca(2+) release channels/ryanodine receptors (RyR2) accelerates heart failure development by stimulating Ca(2+)-dependent hypertrophic signaling. Mice heterozygous for the gain-of-function mutation R176Q/+ in RyR2 and wild-type mice were subjected to transverse aortic constriction. Cardiac function was significantly lower, and cardiac dimensions were larger at 8 weeks after transverse aortic constriction in R176Q/+ compared with wild-type mice. R176Q/+ mice displayed an enhanced hypertrophic response compared with wild-type mice as assessed by heart weight:body weight ratios and cardiomyocyte cross-sectional areas after transverse aortic constriction. Quantitative PCR revealed increased transcriptional activation of cardiac stress genes in R176Q/+ mice after transverse aortic constriction. Moreover, pressure overload resulted in an increased sarcoplasmic reticulum Ca(2+) leak, associated with higher expression levels of the exon 4 splice form of regulator of calcineurin 1, and a decrease in nuclear factor of activated T-cells phosphorylation in R176Q/+ mice compared with wild-type mice. Taken together, our results suggest that RyR2-dependent sarcoplasmic reticulum Ca(2+) leak activates the prohypertrophic calcineurin/nuclear factor of activated T-cells pathway under conditions of pressure overload.
Assuntos
Cálcio/metabolismo , Cardiomegalia/metabolismo , Insuficiência Cardíaca/metabolismo , Hipertensão/complicações , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Animais , Western Blotting , Calcineurina/metabolismo , Cardiomegalia/etiologia , Cardiomegalia/genética , Tamanho Celular , Progressão da Doença , Ecocardiografia , Insuficiência Cardíaca/genética , Camundongos , Miocárdio/metabolismo , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Fatores de Transcrição NFATC/metabolismo , Fosforilação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Retículo Sarcoplasmático/metabolismo , Fatores de TempoRESUMO
BACKGROUND: Mutations in the cardiac ryanodine receptor gene (RyR2) have been recently identified in victims of sudden infant death syndrome. The aim of this study was to determine whether a gain-of-function mutation in RyR2 increases the propensity to cardiac arrhythmias and sudden death in young mice. METHODS AND RESULTS: Incidence of sudden death was monitored prospectively in heterozygous knock-in mice with mutation R176Q in RyR2 (R176Q/+). Young R176Q/+ mice exhibited a higher incidence of sudden death compared with wild-type littermates. Optical mapping of membrane potentials and intracellular calcium in 1- to 7-day-old R176Q/+ and wild-type mice revealed an increased incidence of ventricular ectopy and spontaneous calcium releases in neonatal R176Q/+ mice. Surface ECGs in 3- to 10-day-old mice showed that R176Q/+ mice developed more ventricular arrhythmias after provocation with epinephrine and caffeine. Intracardiac pacing studies in 12- to 18-day-old mice revealed the presence of an arrhythmogenic substrate in R176Q/+ compared with wild-type mice. Reverse transcription-polymerase chain reaction and Western blotting showed that expression levels of other calcium handling proteins were unaltered, suggesting that calcium leak through mutant RyR2 underlies arrhythmogenesis and sudden death in young R176Q/+ mice. CONCLUSIONS: Our findings demonstrate that a gain-of-function mutation in RyR2 confers an increased risk of cardiac arrhythmias and sudden death in young mice and that young R176Q/+ mice may be used as a model for elucidating the complex interplay between genetic and environmental risk factors associated with sudden infant death syndrome.
Assuntos
Sinalização do Cálcio/genética , Mutação , Miocárdio/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Morte Súbita do Lactente/genética , Taquicardia Ventricular/genética , Agonistas Adrenérgicos/farmacologia , Animais , Animais Recém-Nascidos , Sinalização do Cálcio/efeitos dos fármacos , Estimulação Cardíaca Artificial , Modelos Animais de Doenças , Eletrocardiografia , Epinefrina/farmacologia , Técnicas de Introdução de Genes , Predisposição Genética para Doença , Humanos , Lactente , Potenciais da Membrana , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fenótipo , Fatores de Risco , Canal de Liberação de Cálcio do Receptor de Rianodina/efeitos dos fármacos , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Taquicardia Ventricular/complicações , Taquicardia Ventricular/metabolismo , Teofilina/farmacologia , Imagens com Corantes Sensíveis à VoltagemRESUMO
A trial fibrillation (AF), the most common human cardiac arrhythmia, is associated with abnormal intracellular Ca2+ handling. Diastolic Ca2+ release from the sarcoplasmic reticulum via "leaky" ryanodine receptors (RyR2s) is hypothesized to contribute to arrhythmogenesis in AF, but the molecular mechanisms are incompletely understood. Here, we have shown that mice with a genetic gain-of-function defect in Ryr2 (which we termed Ryr2R176Q/+ mice) did not exhibit spontaneous AF but that rapid atrial pacing unmasked an increased vulnerability to AF in these mice compared with wild-type mice. Rapid atrial pacing resulted in increased Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation of RyR2, while both pharmacologic and genetic inhibition of CaMKII prevented AF inducibility in Ryr2R176Q/+ mice. This result suggests that AF requires both an arrhythmogenic substrate (e.g., RyR2 mutation) and enhanced CaMKII activity. Increased CaMKII phosphorylation of RyR2 was observed in atrial biopsies from mice with atrial enlargement and spontaneous AF, goats with lone AF, and patients with chronic AF. Genetic inhibition of CaMKII phosphorylation of RyR2 in Ryr2S2814A knockin mice reduced AF inducibility in a vagotonic AF model. Together, these findings suggest that increased RyR2-dependent Ca2+ leakage due to enhanced CaMKII activity is an important downstream effect of CaMKII in individuals susceptible to AF induction.