RESUMO
COVID-19 is still placing a heavy health and financial burden worldwide. Impairment in patient screening and risk management plays a fundamental role on how governments and authorities are directing resources, planning reopening, as well as sanitary countermeasures, especially in regions where poverty is a major component in the equation. An efficient diagnostic method must be highly accurate, while having a cost-effective profile. We combined a machine learning-based algorithm with mass spectrometry to create an expeditious platform that discriminate COVID-19 in plasma samples within minutes, while also providing tools for risk assessment, to assist healthcare professionals in patient management and decision-making. A cross-sectional study enrolled 815 patients (442 COVID-19, 350 controls and 23 COVID-19 suspicious) from three Brazilian epicenters from April to July 2020. We were able to elect and identify 19 molecules related to the disease's pathophysiology and several discriminating features to patient's health-related outcomes. The method applied for COVID-19 diagnosis showed specificity >96% and sensitivity >83%, and specificity >80% and sensitivity >85% during risk assessment, both from blinded data. Our method introduced a new approach for COVID-19 screening, providing the indirect detection of infection through metabolites and contextualizing the findings with the disease's pathophysiology. The pairwise analysis of biomarkers brought robustness to the model developed using machine learning algorithms, transforming this screening approach in a tool with great potential for real-world application.
Assuntos
COVID-19/diagnóstico , Aprendizado de Máquina , Metabolômica , Adulto , Idoso , Automação , Biomarcadores/metabolismo , Brasil , COVID-19/virologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição de Risco , SARS-CoV-2/isolamento & purificaçãoRESUMO
Zika virus (ZIKV) has the ability to cross placental and brain barriers, causing congenital malformations in neonates and neurological disorders in adults. However, the pathogenic mechanisms of ZIKV-induced neurological complications in adults and congenital malformations are still not fully understood. Gas6 is a soluble TAM receptor ligand able to promote flavivirus internalization and downregulation of immune responses. Here we demonstrate that there is a correlation between ZIKV neurological complications with higher Gas6 levels and the downregulation of genes associated with anti-viral response, as type I IFN due to Socs1 upregulation. Also, Gas6 gamma-carboxylation is essential for ZIKV invasion and replication in monocytes, the main source of this protein, which was inhibited by warfarin. Conversely, Gas6 facilitates ZIKV replication in adult immunocompetent mice and enabled susceptibility to transplacental infection. Our data indicate that ZIKV promotes the upregulation of its ligand Gas6, which contributes to viral infectivity and drives the development of severe adverse outcomes during ZIKV infection.
Assuntos
Doenças do Sistema Nervoso , Infecção por Zika virus , Zika virus , Animais , Feminino , Humanos , Camundongos , Placenta , Gravidez , Replicação Viral , Infecção por Zika virus/complicaçõesRESUMO
Cerebral malaria (CM) is a multifactorial syndrome involving an exacerbated proinflammatory status, endothelial cell activation, coagulopathy, hypoxia, and accumulation of leukocytes and parasites in the brain microvasculature. Despite significant improvements in malaria control, 15% of mortality is still observed in CM cases, and 25% of survivors develop neurologic sequelae for life-even after appropriate antimalarial therapy. A treatment that ameliorates CM clinical signs, resulting in complete healing, is urgently needed. Previously, we showed a hyperbaric oxygen (HBO)-protective effect against experimental CM. Here, we provide molecular evidence that HBO targets brain endothelial cells by decreasing their activation and inhibits parasite and leukocyte accumulation, thus improving cerebral microcirculatory blood flow. HBO treatment increased the expression of aryl hydrocarbon receptor over hypoxia-inducible factor 1-α (HIF-1α), an oxygen-sensitive cytosolic receptor, along with decreased indoleamine 2,3-dioxygenase 1 expression and kynurenine levels. Moreover, ablation of HIF-1α expression in endothelial cells in mice conferred protection against CM and improved survival. We propose that HBO should be pursued as an adjunctive therapy in CM patients to prolong survival and diminish deleterious proinflammatory reaction. Furthermore, our data support the use of HBO in therapeutic strategies to improve outcomes of non-CM disorders affecting the brain.-Bastos, M. F., Kayano, A. C. A. V., Silva-Filho, J. L., Dos-Santos, J. C. K., Judice, C., Blanco, Y. C., Shryock, N., Sercundes, M. K., Ortolan, L. S., Francelin, C., Leite, J. A., Oliveira, R., Elias, R. M., Câmara, N. O. S., Lopes, S. C. P., Albrecht, L., Farias, A. S., Vicente, C. P., Werneck, C. C., Giorgio, S., Verinaud, L., Epiphanio, S., Marinho, C. R. F., Lalwani, P., Amino, R., Aliberti, J., Costa, F. T. M. Inhibition of hypoxia-associated response and kynurenine production in response to hyperbaric oxygen as mechanisms involved in protection against experimental cerebral malaria.
Assuntos
Encéfalo/metabolismo , Hipóxia/metabolismo , Cinurenina/metabolismo , Malária Cerebral/metabolismo , Oxigênio/metabolismo , Animais , Circulação Cerebrovascular/fisiologia , Células Endoteliais/metabolismo , Feminino , Oxigenoterapia Hiperbárica/métodos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Microcirculação/fisiologiaRESUMO
BACKGROUND: Technical limitations for culturing the human malaria parasite Plasmodium vivax have impaired the discovery of vaccine candidates, challenging the malaria eradication agenda. The immunogenicity of the M2 domain of the Merozoite Adhesive Erythrocytic Binding Protein (MAEBL) antigen cloned from the Plasmodium yoelii murine parasite, has been previously demonstrated. RESULTS: Detailed epitope mapping of MAEBL through immunoinformatics identified several MHCI, MHCII and B cell epitopes throughout the peptide, with several of these lying in the M2 domain and being conserved between P. vivax, P. yoelii and Plasmodium falciparum, hinting that the M2-MAEBL is pan-reactive. This hypothesis was tested through functional assays, showing that P. yoelii M2-MAEBL antisera are able to recognize and inhibit erythrocyte invasion from both P. falciparum and P. vivax parasites isolated from Thai patients, in ex vivo assays. Moreover, the sequence of the M2-MAEBL is shown to be highly conserved between P. vivax isolates from the Amazon and Thailand, indicating that the MAEBL antigen may constitute a vaccine candidate outwitting strain-specific immunity. CONCLUSIONS: The MAEBL antigen is promising candidate towards the development of a malaria vaccine.
Assuntos
Antígenos de Protozoários/imunologia , Mapeamento de Epitopos , Plasmodium yoelii/imunologia , Proteínas de Protozoários/imunologia , Animais , Antígenos de Protozoários/genética , Biologia Computacional , Sequência Conservada , Epitopos/genética , Epitopos/imunologia , Humanos , Vacinas Antimaláricas/isolamento & purificação , Malária Falciparum/prevenção & controle , Malária Vivax/prevenção & controle , Camundongos Endogâmicos C57BL , Plasmodium falciparum/genética , Plasmodium falciparum/imunologia , Plasmodium vivax/genética , Plasmodium vivax/imunologia , Plasmodium yoelii/genética , Proteínas de Protozoários/genética , TailândiaRESUMO
Background: Zika virus (ZIKV) infections have been linked to different levels of clinical outcomes, ranging from mild rash and fever to severe neurological complications and congenital malformations. Methods: We investigated the clinical and immunological response, focusing on the immune mediators profile in 95 acute ZIKV-infected adult patients from Campinas, Brazil. These patients included 6 pregnant women who later delivered during the course of this study. Clinical observations were recorded during hospitalization. Levels of 45 immune mediators were quantified using multiplex microbead-based immunoassays. Results: Whereas 11.6% of patients had neurological complications, 88.4% displayed mild disease of rash and fever. Several immune mediators were specifically higher in ZIKV-infected patients, and levels of interleukin 10, interferon gamma-induced protein 10 (IP-10), and hepatocyte growth factor differentiated between patients with or without neurological complications. Interestingly, higher levels of interleukin 22, monocyte chemoattractant protein 1, TNF-α, and IP-10 were observed in ZIKV-infected pregnant women carrying fetuses with fetal growth-associated malformations. Notably, infants with congenital central nervous system deformities had significantly higher levels of interleukin 18 and IP-10 but lower levels of hepatocyte growth factor than those without such abnormalities born to ZIKV-infected mothers. Conclusions: This study identified several key markers for the control of ZIKV pathogenesis. This will allow a better understanding of the molecular mechanisms of ZIKV infection in patients.
Assuntos
Citocinas/sangue , Malformações do Sistema Nervoso/epidemiologia , Complicações Infecciosas na Gravidez/epidemiologia , Infecção por Zika virus/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Brasil/epidemiologia , Criança , Feminino , Retardo do Crescimento Fetal/virologia , Humanos , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Malformações do Sistema Nervoso/virologia , Gravidez , Complicações Infecciosas na Gravidez/virologia , Resultado da Gravidez , Carga Viral , Adulto Jovem , Zika virus , Infecção por Zika virus/complicaçõesRESUMO
Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes acute, subacute, and chronic human arthritogenic diseases and, in rare instances, can lead to neurological complications and death. Here, we combined epidemiological, virological, histopathological, cytokine, molecular dynamics, metabolomic, proteomic, and genomic analyses to investigate viral and host factors that contribute to chikungunya-associated (CHIK) death. Our results indicate that CHIK deaths are associated with multi-organ infection, central nervous system damage, and elevated serum levels of pro-inflammatory cytokines and chemokines compared with survivors. The histopathologic, metabolite, and proteomic signatures of CHIK deaths reveal hemodynamic disorders and dysregulated immune responses. The CHIKV East-Central-South-African lineage infecting our study population causes both fatal and survival cases. Additionally, CHIKV infection impairs the integrity of the blood-brain barrier, as evidenced by an increase in permeability and altered tight junction protein expression. Overall, our findings improve the understanding of CHIK pathophysiology and the causes of fatal infections.
Assuntos
Febre de Chikungunya , Vírus Chikungunya , Animais , Humanos , Febre de Chikungunya/complicações , Proteômica , Vírus Chikungunya/genética , Citocinas/metabolismoRESUMO
We studied the implication of focal adhesion kinase (FAK) in cardiac mitochondrial biogenesis induced by mechanical stress. Prolonged stretching (2-12 h) of neonatal rat ventricular myocytes (NRVM) upregulated the main components of mitochondrial transcription cascade [peroxisome proliferator-activated receptor coactivator-1 (PGC-1α), nuclear respiratory factor (NRF-1), and mitochondrial transcription factor A]. Concomitantly, prolonged stretching enhanced mitochondrial biogenesis [copy number of mitochondrial DNA (mtDNA), content of the subunit IV of cytochrome oxidase, and mitochondrial staining-green fluorescence intensity of Mitotracker green] and induced the hypertrophic growth (cell size and atrial natriuretic peptide transcripts) of NRVM. Furthermore, the stretching of NRVM enhanced phosphorylation, nuclear localization, and association of FAK with PGC-1α. Recombinant FAK COOH-terminal, but not the NH(2)-terminal or kinase domain, precipitated PGC-1α from nuclear extracts of NRVM. Depletion of FAK by RNA interference suppressed the upregulation of PGC-1α and NRF-1 and markedly attenuated the enhanced mitochondrial biogenesis and hypertrophic growth of stretched NRVM. In the context of energy metabolism, FAK depletion became manifest by a reduction of ATP levels in stretched NRVM. Complementary studies in adult mice left ventricle demonstrated that pressure overload upregulated PGC-1α, NRF-1, and mtDNA. In vivo FAK silencing transiently attenuated the upregulation of PGC-1α, NRF-1, and mtDNA, as well as the left ventricular hypertrophy induced by pressure overload. In conclusion, activation of FAK signaling seems to be important for conferring enhanced mitochondrial biogenesis coupled to the hypertrophic growth of cardiomyocytes in response to mechanical stress, via control of mitochondrial transcription cascade.
Assuntos
Quinase 1 de Adesão Focal/metabolismo , Mitocôndrias Cardíacas/enzimologia , Miócitos Cardíacos/enzimologia , Estresse Mecânico , Animais , Animais Recém-Nascidos , Células Cultivadas , DNA Mitocondrial/metabolismo , DNA Mitocondrial/fisiologia , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/fisiologia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/fisiologia , Camundongos , Proteínas Mitocondriais/metabolismo , Proteínas Mitocondriais/fisiologia , Miócitos Cardíacos/fisiologia , Fator 1 Relacionado a NF-E2/metabolismo , Fator 1 Relacionado a NF-E2/fisiologia , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a RNA/fisiologia , Ratos , Ratos Wistar , Fatores de Transcrição/metabolismo , Fatores de Transcrição/fisiologia , Regulação para CimaRESUMO
Plasmodium vivax is the major cause of human malaria in the Americas. How P. vivax infection can lead to poor clinical outcomes, despite low peripheral parasitaemia, remains a matter of intense debate. Estimation of total P. vivax biomass based on circulating markers indicates existence of a predominant parasite population outside of circulation. In this study, we investigate associations between both peripheral and total parasite biomass and host response in vivax malaria. We analysed parasite and host signatures in a cohort of uncomplicated vivax malaria patients from Manaus, Brazil, combining clinical and parasite parameters, multiplexed analysis of host responses, and ex vivo assays. Patterns of clinical features, parasite burden, and host signatures measured in plasma across the patient cohort were highly heterogenous. Further data deconvolution revealed two patient clusters, here termed Vivaxlow and Vivaxhigh. These patient subgroups were defined based on differences in total parasite biomass but not peripheral parasitaemia. Overall Vivaxlow patients clustered with healthy donors and Vivaxhigh patients showed more profound alterations in haematological parameters, endothelial cell (EC) activation, and glycocalyx breakdown and levels of cytokines regulating different haematopoiesis pathways compared to Vivaxlow. Vivaxhigh patients presented more severe thrombocytopenia and lymphopenia, along with enrichment of neutrophils in the peripheral blood and increased neutrophil-to-lymphocyte ratio (NLCR). When patients' signatures were combined, high association of total parasite biomass with a subset of markers of EC activation, thrombocytopenia, and lymphopenia severity was observed. Finally, machine learning models defined a combination of host parameters measured in the circulation that could predict the extent of parasite infection outside of circulation. Altogether, our data show that total parasite biomass is a better predictor of perturbations in host homeostasis in P. vivax patients than peripheral parasitaemia. This supports the emerging paradigm of a P. vivax tissue reservoir, particularly in the haematopoietic niche of bone marrow and spleen.
Assuntos
Malária Vivax/parasitologia , Parasitemia/parasitologia , Plasmodium vivax/fisiologia , Adulto , Biomassa , Feminino , Humanos , Malária Vivax/patologia , Malária Vivax/fisiopatologia , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
Platelets drive endothelial cell activation in many diseases. However, if this occurs in Plasmodium vivax malaria is unclear. As platelets have been reported to be activated and to play a role in inflammatory response during malaria, we hypothesized that this would correlate with endothelial alterations during acute illness. We performed platelet flow cytometry of PAC-1 and P-selectin. We measured platelet markers (CXCL4, CD40L, P-selectin, Thrombopoietin, IL-11) and endothelial activation markers (ICAM-1, von Willebrand Factor and E-selectin) in plasma with a multiplex-based assay. The values of each mediator were used to generate heatmaps, K-means clustering and Principal Component analysis. In addition, we determined pair-wise Pearson's correlation coefficients to generate correlation networks. Platelet counts were reduced, and mean platelet volume increased in malaria patients. The activation of circulating platelets in flow cytometry did not differ between patients and controls. CD40L levels (Median [IQ]: 517 [406-651] vs. 1029 [732-1267] pg/mL, P = 0.0001) were significantly higher in patients, while P-selectin and CXCL4 showed a nonsignificant trend towards higher levels in patients. The network correlation approach demonstrated the correlation between markers of platelet and endothelial activation, and the heatmaps revealed a distinct pattern of activation in two subsets of P. vivax patients when compared to controls. Although absolute platelet activation was not strong in uncomplicated vivax malaria, markers of platelet activity and production were correlated with higher endothelial cell activation, especially in a specific subset of patients.
Assuntos
Plaquetas/citologia , Malária Vivax/sangue , Adulto , Plaquetas/metabolismo , Ligante de CD40/genética , Ligante de CD40/metabolismo , Selectina E/genética , Selectina E/metabolismo , Células Endoteliais/metabolismo , Feminino , Humanos , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/metabolismo , Interleucina-11/genética , Interleucina-11/metabolismo , Malária Vivax/genética , Malária Vivax/metabolismo , Masculino , Selectina-P/genética , Selectina-P/metabolismo , Ativação Plaquetária , Contagem de Plaquetas , Adulto JovemRESUMO
Zika virus (ZIKV) greatly impacted the international scientific and public health communities in the last two years due to its association with microcephaly and other neonatal alterations. This review will discuss lessons learned from viral pathogenesis, epidemiology and clinical findings observed during the ZIKV outbreak occurred between 2014 and 2016 in Brazil.
Assuntos
Surtos de Doenças , Infecção por Zika virus/epidemiologia , Infecção por Zika virus/virologia , Zika virus/patogenicidade , Brasil/epidemiologia , Feminino , Humanos , Microcefalia/epidemiologia , Microcefalia/etiologia , Microcefalia/virologia , Placenta/virologia , Gravidez , Tropismo Viral , Zika virus/fisiologia , Infecção por Zika virus/complicações , Infecção por Zika virus/transmissãoRESUMO
Despite the recent outbreak of Zika virus (ZIKV), there are still no approved treatments, and early-stage compounds are probably many years away from approval. A comprehensive A-Z review of the recent advances in ZIKV drug discovery efforts is presented, highlighting drug repositioning and computationally guided compounds, including discovered viral and host cell inhibitors. Promising ZIKV molecular targets are also described and discussed, as well as targets belonging to the host cell, as new opportunities for ZIKV drug discovery. All this knowledge is not only crucial to advancing the fight against the Zika virus and other flaviviruses but also helps us prepare for the next emerging virus outbreak to which we will have to respond.
Assuntos
Antivirais/farmacologia , Descoberta de Drogas , Terapia de Alvo Molecular/métodos , Infecção por Zika virus/tratamento farmacológico , Zika virus/efeitos dos fármacos , Antivirais/química , Antivirais/uso terapêutico , Humanos , Modelos Biológicos , Estrutura MolecularRESUMO
Infection with Zika virus (ZIKV), a mosquito-borne flavivirus has been casually linked with increased congenital microcephaly in Brazil from 2015 through 2016. Sensitive and specific diagnosis of patients with Zika fever (ZIKF) remains critical for patient management. We developed a ZIKV NS5 qRT-PCR assay by combining primers described by Balm et al. and a new Taqman probe. The assay was evaluated and compared with another assay described by Lanciotti et al. (ZIKV 1107) using 51 blood and 42 urine samples from 54 suspected ZIKV patients. ZIKV NS5 performed better in terms of sensitivity with more samples detected as ZIKV-positive (n = 37) than ZIKV 1107 (n = 34) for urine, and ZIKV-positive (n = 29) than ZIKV 1107 (n = 26) for blood. Both assays displayed good overall agreement for urine (κappa = 0.770) and blood (κappa = 0.825) samples. Improved availability of validated diagnostic tests, such ZIKV NS5 qRT-PCR, will be critical to ensure adequate and accurate ZIKV diagnosis.
Assuntos
Surtos de Doenças , RNA Viral/sangue , Infecção por Zika virus/epidemiologia , Zika virus/genética , Adulto , Brasil/epidemiologia , Feminino , Humanos , Limite de Detecção , Masculino , Pessoa de Meia-Idade , Sensibilidade e Especificidade , Adulto Jovem , Infecção por Zika virus/diagnóstico , Infecção por Zika virus/virologiaRESUMO
MicroRNAs (miRNAs), a class of small non-coding regulatory RNAs, have been detected in a variety of organisms ranging from ancient unicellular eukaryotes to mammals. They have been associated with numerous molecular mechanisms involving developmental, physiological and pathological changes of cells and tissues. Despite the fact that miRNA-silencing mechanisms appear to be absent in some Apicomplexan species, an increasing number of studies have reported a role for miRNAs in host-parasite interactions. Host miRNA expression can change following parasite infection and the consequences can lead, for instance, to parasite clearance. In this context, the immune system signaling appears to have a crucial role.
Assuntos
Cryptosporidium/imunologia , Regulação da Expressão Gênica/imunologia , Interações Hospedeiro-Parasita/genética , MicroRNAs/genética , Plasmodium/imunologia , Toxoplasma/imunologia , Criptosporidiose/imunologia , Criptosporidiose/microbiologia , Regulação da Expressão Gênica/genética , Interações Hospedeiro-Parasita/imunologia , Humanos , Malária/imunologia , Malária/microbiologia , Transdução de Sinais/imunologia , Toxoplasmose/imunologia , Toxoplasmose/microbiologiaRESUMO
Mechanical stress is a major triggering stimulus for the installation of cardiac hypertrophy as well as for the structural and functional deterioration occurring in the hypertrophy decompensation. The sensing of mechanical forces and their conversion into biochemical signals depend on the integrity of subcellular structures such as the costameres and Z-disks. Signaling molecules concentrated into these structures are thought to be activated by the stress-induced deformation of structural proteins. Evidence also indicates that Ca2+ may be involved in mediating the mechanical forces conversion into biochemical signals and biological responses. Ca2+ channels, transporters and activated proteins are concentrated at the junctions between the T-tubules and the sarcoplasmic reticulum which are in close proximity to the costameres and Z-disks. This provides a structural basis for the influence of mechanical forces on Ca2+ transport and on the events related to signaling molecules clustered in the costameres and the Z-disks. Emerging data reviewed here are providing insight into how Ca2+ and mechanical mediated signaling are coordinated to modulate the functional and trophic responses of cardiac myocytes to mechanical stress.
Assuntos
Cálcio/metabolismo , Cardiomegalia/etiologia , Mecanotransdução Celular/fisiologia , Miócitos Cardíacos/fisiologia , Estresse Mecânico , Costâmeros/metabolismo , Humanos , Miócitos Cardíacos/metabolismoRESUMO
Transient dephosphorylation of FAK at Tyr-397 is required for cell cycle withdrawal early on during myogenesis. Here, we show that upon serum starvation of C2C12 myoblasts, FAK is transiently dephosphorylated in parallel with SHP-2 activation and association with FAK. SHP-2 knockdown by RNA interference suppressed the transient upregulation of SHP-2 and dephosphorylation of FAK during myogenesis. Furthermore, depletion of SHP-2 retarded the cell cycle withdrawal and the differentiation of serum-starved myoblasts into myotubes. These data provide a mechanistic basis for the reduction in FAK activity in differentiating myoblasts, indicating that myogenesis is critically triggered by FAK/SHP-2 complex.
Assuntos
Quinase 1 de Adesão Focal/metabolismo , Desenvolvimento Muscular , Proteína Tirosina Fosfatase não Receptora Tipo 11/fisiologia , Transdução de Sinais , Animais , Ciclo Celular , Diferenciação Celular , Células Cultivadas , Camundongos , Músculo Esquelético/citologia , Mioblastos/citologia , Fosforilação , Regulação para CimaRESUMO
BACKGROUND: The activation of the members of the myocyte enhancer factor-2 family (MEF2A, B, C and D) of transcription factors promotes cardiac hypertrophy and failure. However, the role of its individual components in the pathogenesis of cardiac hypertrophy remains unclear. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we investigated whether MEF2C plays a role in mediating the left ventricular hypertrophy by pressure overload in mice. The knockdown of myocardial MEF2C induced by specific small interfering RNA (siRNA) has been shown to attenuate hypertrophy, interstitial fibrosis and the rise of ANP levels in aortic banded mice. We detected that the depletion of MEF2C also results in lowered levels of both PGC-1alpha and mitochondrial DNA in the overloaded left ventricle, associated with enhanced AMP:ATP ratio. Additionally, MEF2C depletion was accompanied by defective activation of S6K in response to pressure overload. Treatment with the amino acid leucine stimulated S6K and suppressed the attenuation of left ventricular hypertrophy and fibrosis in the aforementioned aortic banded mice. CONCLUSION/SIGNIFICANCE: These findings represent new evidences that MEF2C depletion attenuates the hypertrophic responses to mechanical stress and highlight the potential of MEF2C to be a target for new therapies to cardiac hypertrophy and failure.