RESUMO
Several GWAS reported Myocyte Enhancer Factor 2 C (MEF2C) gene associations with white matter microstructure and psychiatric disorders, and MEF2C involvement in pathways related to neuronal development suggests a common biological factor underlying these phenotypes. We aim to refine the MEF2C effects in the brain relying on an integrated analysis of white matter and psychiatric phenotypes in an extensively characterized sample. This study included 870 Brazilian adults (47% from an attention-deficit/hyperactivity disorder outpatient clinic) assessed through standardized psychiatric interviews, 139 of which underwent a magnetic resonance imaging scan. We evaluated variants in the MEF2C region using two approaches: 1) a gene-wide analysis, which uses the sum of polymorphism effects, and 2) SNP analyses, restricted to the independent variants within the gene. The outcomes included psychiatric phenotypes and fractional anisotropy for brain images. Results: The gene-wide analyses pointed to a nominal association between MEF2C and the Temporal Portion of the Superior Longitudinal Fasciculus (SLFTEMP). The SNP analysis identified four independent variants significantly associated with SLFTEMP and one (rs4218438) with Substance Use Disorder. Our findings showing specific associations of MEF2C variants with temporal-frontal circuitry components may help to elucidate how the MEF2C gene underlies a broad range of psychiatric phenotypes since these regions are relevant to executive and cognitive functions.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade , Substância Branca , Humanos , Substância Branca/diagnóstico por imagem , Substância Branca/patologia , Fatores de Transcrição MEF2/genética , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Imageamento por Ressonância Magnética , Transtorno do Deficit de Atenção com Hiperatividade/genética , AnisotropiaRESUMO
Myocyte enhancer factor 2D (MEF2D) are members of the myocyte enhancer factor 2 (MEF2), a supergene family and are thought to be related to the development and regeneration of skeletal muscle. We selected a microsatellite locus located in the MEF2D gene to study the slaughter characteristics of Xingyi duck and discuss whether the locus could be used as a molecular genetic marker associated with the slaughter characteristics. To further study the function of this gene, we cloned the coding region of the MEF2D gene and expressed it in the prokaryotic expression system. We amplified exon 9 of MEF2D gene by PCR and analyzed after sequencing. The entire CDS region was amplified by RT-PCR. The prokaryotic expression vector was constructed by double enzyme digestion. Results showed that there was a significant correlation between the microsatellite polymorphism of exon 9 of the MEF2D gene and the eviscerated weight rate of Xingyi duck (p<0.05). The eviscerated weight rate of the aa (40/40) genotype was significantly higher than that of the ab (40/49) genotype. The CDS region of the MEF2D gene was cloned with a length of 1557 bp. The prokaryotic expression vector pET32a(+)-MEF2D was constructed. The results provide a foundation for future studies examining the function of the MEF2D.(AU)
Assuntos
Animais , Patos/crescimento & desenvolvimento , Patos/genética , Polimorfismo Genético , Células Musculares , Células ProcarióticasRESUMO
Myocyte enhancer factor 2D (MEF2D) are members of the myocyte enhancer factor 2 (MEF2), a supergene family and are thought to be related to the development and regeneration of skeletal muscle. We selected a microsatellite locus located in the MEF2D gene to study the slaughter characteristics of Xingyi duck and discuss whether the locus could be used as a molecular genetic marker associated with the slaughter characteristics. To further study the function of this gene, we cloned the coding region of the MEF2D gene and expressed it in the prokaryotic expression system. We amplified exon 9 of MEF2D gene by PCR and analyzed after sequencing. The entire CDS region was amplified by RT-PCR. The prokaryotic expression vector was constructed by double enzyme digestion. Results showed that there was a significant correlation between the microsatellite polymorphism of exon 9 of the MEF2D gene and the eviscerated weight rate of Xingyi duck (p<0.05). The eviscerated weight rate of the aa (40/40) genotype was significantly higher than that of the ab (40/49) genotype. The CDS region of the MEF2D gene was cloned with a length of 1557 bp. The prokaryotic expression vector pET32a(+)-MEF2D was constructed. The results provide a foundation for future studies examining the function of the MEF2D.
Assuntos
Animais , Células Musculares , Células Procarióticas , Patos/crescimento & desenvolvimento , Patos/genética , Polimorfismo GenéticoRESUMO
BACKGROUND: A pathophysiological link exists between dysregulation of MEF2C transcription factors and heart failure (HF), but the underlying mechanisms remain elusive. Alternative splicing of MEF2C exons α, ß and γ provides transcript diversity with gene activation or repression functionalities. METHODS: Neonatal and adult rat ventricular myocytes were used to overexpress MEF2C splicing variants γ+ (repressor) or γ-, or the inactive MEF2Cγ+23/24 (K23T/R24L). Phenotypic alterations in cardiomyocytes were determined by confocal and electron microscopy, flow cytometry and DNA microarray. We used transgenic mice with cardiac-specific overexpression of MEF2Cγ+ or MEF2Cγ- to explore the impact of MEF2C variants in cardiac phenotype. Samples of non-infarcted areas of the left ventricle from patients and mouse model of myocardial infarction were used to detect the expression of MEF2Cγ+ in failing hearts. FINDINGS: We demonstrate a previously unrealized upregulation of the transrepressor MEF2Cγ+ isoform in human and mouse failing hearts. We show that adenovirus-mediated overexpression of MEF2Cγ+ downregulates multiple MEF2-target genes, and drives incomplete cell-cycle reentry, partial dedifferentiation and apoptosis in the neonatal and adult rat. None of these changes was observed in cardiomyocytes overexpressing MEF2Cγ-. Transgenic mice overexpressing MEF2Cγ+, but not the MEF2Cγ-, developed dilated cardiomyopathy, correlated to cell-cycle reentry and apoptosis of cardiomyocytes. INTERPRETATION: Our results provide a mechanistic link between MEF2Cγ+ and deleterious abnormalities in cardiomyocytes, supporting the notion that splicing dysregulation in MEF2C towards the selection of the MEF2Cγ+ variant contributes to the pathogenesis of HF by promoting cardiomyocyte dropout. FUNDING: São Paulo Research Foundation (FAPESP); Brazilian National Research Council (CNPq).
Assuntos
Ciclo Celular/genética , Regulação da Expressão Gênica , Predisposição Genética para Doença , Variação Genética , Insuficiência Cardíaca/etiologia , Insuficiência Cardíaca/metabolismo , Processamento Alternativo , Animais , Apoptose/genética , Modelos Animais de Doenças , Estudos de Associação Genética , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/terapia , Humanos , Fatores de Transcrição MEF2/genética , Camundongos , Camundongos Transgênicos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/ultraestrutura , RatosRESUMO
Prenatal stress (PS) induces molecular changes that alter neural connectivity, increasing the risk for neuropsychiatric disorders. Here we analyzed -in the hippocampus of adult rats exposed to PS- the epigenetic signature mediating the PS-induced neuroplasticity changes. Furthermore, using cultured hippocampal neurons, we investigated the effects on neuroplasticity of an epigenetic modulator. PS induced significant modifications in the mRNA levels of stress-related transcription factor MEF2A, SUV39H1 histone methyltransferase, and TET1 hydroxylase, indicating that PS modifies gene expression through chromatin remodeling. In in vitro analysis, histone acetylation inhibition with apicidin increased filopodium density, suggesting that the external regulation of acetylation levels might modulate neuronal morphology. These results offer a way to enhance neural connectivity that could be considered to revert PS effects.
Assuntos
Epigênese Genética , Código das Histonas , Plasticidade Neuronal , Efeitos Tardios da Exposição Pré-Natal/genética , Estresse Psicológico/genética , Animais , Células Cultivadas , Dioxigenases/genética , Dioxigenases/metabolismo , Feminino , Hipocampo/citologia , Hipocampo/crescimento & desenvolvimento , Hipocampo/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Fatores de Transcrição MEF2/genética , Fatores de Transcrição MEF2/metabolismo , Masculino , Metiltransferases/genética , Metiltransferases/metabolismo , Neurogênese , Neurônios/citologia , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Peptídeos Cíclicos/farmacologia , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Estresse Psicológico/metabolismo , Estresse Psicológico/fisiopatologiaRESUMO
Testosterone is known to induce cardiac hypertrophy through androgen receptor (AR)-dependent and -independent pathways, but the molecular underpinnings of the androgen action remain poorly understood. Previous work has shown that Ca2+/calmodulin-dependent protein kinase II (CaMKII) and myocyte-enhancer factor 2 (MEF2) play key roles in promoting cardiac myocyte growth. In order to gain mechanistic insights into the action of androgens on the heart, we investigated how testosterone affects CaMKII and MEF2 in cardiac myocyte hypertrophy by performing studies on cultured rat cardiac myocytes and hearts obtained from adult male orchiectomized (ORX) rats. In cardiac myocytes, MEF2 activity was monitored using a luciferase reporter plasmid, and the effects of CaMKII and AR signaling pathways on MEF2C were examined by using siRNAs and pharmacological inhibitors targeting these two pathways. In the in vivo studies, ORX rats were randomly assigned to groups that were administered vehicle or testosterone (125 mgâ kg-1â week-1) for 5 weeks, and plasma testosterone concentrations were determined using ELISA. Cardiac hypertrophy was evaluated by measuring well-characterized hypertrophy markers. Moreover, western blotting was used to assess CaMKII and phospholamban (PLN) phosphorylation, and MEF2C and AR protein levels in extracts of left-ventricle tissue from control and testosterone-treated ORX rats. Whereas testosterone treatment increased the phosphorylation levels of CaMKII (Thr286) and phospholambam (PLN) (Thr17) in cardiac myocytes in a time- and concentration-dependent manner, testosterone-induced MEF2 activity and cardiac myocyte hypertrophy were prevented upon inhibition of CaMKII, MEF2C, and AR signaling pathways. Notably, in the hypertrophied hearts obtained from testosterone-administered ORX rats, both CaMKII and PLN phosphorylation levels and AR and MEF2 protein levels were increased. Thus, this study presents the first evidence indicating that testosterone activates MEF2 through CaMKII and AR signaling. Our findings suggest that an orchestrated mechanism of action involving signal transduction and transcription pathways underlies testosterone-induced cardiac myocyte hypertrophy.
RESUMO
Gene regulatory networks are useful to understand the activity behind the complex mechanisms in transcriptional regulation. A main goal in contemporary biology is using such networks to understand the systemic regulation of gene expression. In this work, we carried out a systematic study of a transcriptional regulatory network derived from a comprehensive selection of all potential transcription factor interactions downstream from MEF2C, a human transcription factor master regulator. By analyzing the connectivity structure of such network, we were able to find different biologically functional processes and specific biochemical pathways statistically enriched in communities of genes into the network, such processes are related to cell signaling, cell cycle and metabolism. In this way we further support the hypothesis that structural properties of biological networks encode an important part of their functional behavior in eukaryotic cells.
RESUMO
We report the case of a young girl who was presented with complex clinical symptoms caused by the deletion of contiguous genes: RASA1 and MEF2C, located on chromosome 5q14.3. Specifically, the diagnosis of her skin disorder and vascular malformations involving central nervous system is consistent with a RASopathy. The child's neurological manifestations are observed in most patients suffering from 5q14.3 by deletion or mutation of the MEF2C gene. A review of the literature allowed us to conclude that the contiguous deletion of genes RASA1 and MEF2C fulfills the criteria for the diagnosis of a Neurocutaneous syndrome as proposed by Carr et al. [2011]. We also assessed the penetrance of RASA1 and clinical manifestations of MEF2C according to the type of deletion. This child described presents the complete symptomatology of both deleted genes. We would also like to highlight the progression of the disorder.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 5 , Síndromes Neurocutâneas/diagnóstico , Síndromes Neurocutâneas/genética , Proteína p120 Ativadora de GTPase/genética , Vasos Sanguíneos/anormalidades , Vasos Sanguíneos/metabolismo , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/fisiopatologia , Criança , Progressão da Doença , Feminino , Deleção de Genes , Humanos , Fatores de Transcrição MEF2/deficiência , Fatores de Transcrição MEF2/genética , Síndromes Neurocutâneas/patologia , Síndromes Neurocutâneas/fisiopatologia , Penetrância , Pele/irrigação sanguínea , Pele/metabolismo , Pele/patologia , Proteína p120 Ativadora de GTPase/deficiênciaRESUMO
AIMS: The insulin-sensitive glucose transporter protein GLUT4 (solute carrier family 2 member 4 (Slc2a4) gene) plays a key role in glycemic homeostasis. Decreased GLUT4 expression is a current feature in insulin resistant conditions such as diabetes, and the restoration of GLUT4 content improves glycemic control. This study investigated the effect of insulin upon Slc2a4/GLUT4 expression, focusing on the AT-rich element, E-box and nuclear factor NF-kappa-B (NFKB) site. MAIN METHODS: Rat soleus muscles were incubated during 180 min with insulin, added or not with wortmannin (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit gamma isoform (PI3K)-inhibitor), ML9 (serine/threonine protein kinase (AKT) inhibitor) and tumor necrosis factor (TNF, GLUT4 repressor), and processed for analysis of GLUT4 protein (Western blotting); Slc2a4, myocyte enhancer factor 2a/d (Mef2a/d), hypoxia inducible factor 1a (Hif1a), myogenic differentiation 1 (Myod1) and nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (Nfkb1) messenger ribonucleic acids (mRNAs) (polymerase chain reaction (PCR)); and AT-rich- (myocyte-specific enhancer factor 2 (MEF2)-binding site), E-box- (hypoxia inducible factor 1 alpha (HIF1A)- and myoblast determination protein 1 (MYOD1)-binding site), and NFKB-binding activity (electrophoretic mobility assay). KEY FINDINGS: Insulin increased Slc2a4 mRNA expression (140%) and nuclear proteins binding to AT-rich and E-box elements (~90%), all effects were prevented by wortmannin and ML9. Insulin also increased Mef2a/d and Myod1 mRNA expression, suggesting the participation of these transcriptional factors in the Slc2a4 enhancing effect. Conversely, insulin decreased Nfkb1 mRNA expression and protein binding to the NFKB-site (~50%). Furthermore, TNF-induced inhibition of GLUT4 expression (~40%) was prevented by insulin in an NFKB-binding repressing mechanism. GLUT4 protein paralleled the Slc2a4 mRNA regulations. SIGNIFICANCE: Insulin enhances the Slc2a4/GLUT4 expression in the skeletal muscle by activating AT-rich and E-box elements, in a PI3K/AKT-dependent mechanism, and repressing NFKB-site activity as well. These results unravel how post-prandial increase of insulin may guarantee GLUT4 expression, and how the insulin signaling impairment can participate in insulin resistance-induced repression of GLUT4.
Assuntos
Transportador de Glucose Tipo 4/genética , Resistência à Insulina , Insulina/farmacologia , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Sequência Rica em At/genética , Animais , Linfócitos B/metabolismo , Sítios de Ligação , Western Blotting , Elementos E-Box/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Masculino , Músculo Esquelético/metabolismo , NF-kappa B/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Fatores de Transcrição/genéticaRESUMO
The role of myogenic enhancer transcription factor 2a (MEF2A) in avian muscle during fetal development is unknown. In this work, we cloned the duck MEF2A cDNA sequence (GenBank accession no. HM460752) and examined its developmental expression profiles in cardiac muscle, non-vascular smooth muscle and skeletal muscle. Duck MEF2A cDNA comprised 1479 bp encoding 492 amino acid residues. In silico analysis showed that MEF2A contained MADS (MCM1, AGAMOUS, DEFICIENS and SRF - serum response factor), MEF2 and mitogen-activated protein kinase (MAPK) transcription domains with high homology to related proteins in other species. Modified sites in these domains were conserved among species and several variants were found. Quantitative PCR showed that MEF2A was expressed in all three muscles at each developmental stage examined, with the expression in smooth muscle being higher than in the other muscles. These results indicate that the conserved domains of duck MEF2A, including the MADS and MEF2 domains, are important for MEF2A transcription factor function. The expression of MEF2A in duck smooth muscle and cardiac muscle suggests that MEF2A plays a role in these two tissues.
RESUMO
The role of myogenic enhancer transcription factor 2a (MEF2A) in avian muscle during fetal development is unknown. In this work, we cloned the duck MEF2A cDNA sequence (GenBank accession no. HM460752) and examined its developmental expression profiles in cardiac muscle, non-vascular smooth muscle and skeletal muscle. Duck MEF2A cDNA comprised 1479 bp encoding 492 amino acid residues. In silico analysis showed that MEF2A contained MADS (MCM1, AGAMOUS, DEFICIENS and SRF -serum response factor), MEF2 and mitogen-activated protein kinase (MAPK) transcription domains with high homology to related proteins in other species. Modified sites in these domains were conserved among species and several variants were found. Quantitative PCR showed that MEF2A was expressed in all three muscles at each developmental stage examined, with the expression in smooth muscle being higher than in the other muscles. These results indicate that the conserved domains of duck MEF2A, including the MADS and MEF2 domains, are important for MEF2A transcription factor function. The expression of MEF2A in duck smooth muscle and cardiac muscle suggests that MEF2A plays a role in these two tissues.
Assuntos
Clonagem Molecular , Simulação por Computador , Músculos , TranscriptomaRESUMO
OBJECTIVE: As axon outgrowth and dentate granule cell neurogenesis are hallmarks of hippocampal development and are also the two morphologic changes in the structure of the dentate gyrus after status epilepticus (SE), we hypothesized that molecules involved in normal development may also play a role during epileptogenesis. METHOD: Using in situ hybridization, we have characterized mRNA expression of myocyte-specific enhancer binding factor 2C (MEF2C) in the dentate gyrus during development (P0, P3, P7, P14 and P28) and at multiple time points following pilocarpine-induced SE (3, 7, 14, 28 days after SE). RESULTS: It was demonstrated that MEF2C is up-regulated during development (P0, P3, P7, P14 and P28) and in the adult rat dentate gyrus following SE (3, 7, 14, 28 days after SE). CONCLUSIONS: The molecules controlling cell-fate decisions in the developing dentate gyrus are also operative during epileptogenesis.
OBJETIVO: Como o crescimento axonal e a neurogênese do giro denteado são características intrínsecas do hipocampo durante o processo de desenvolvimento, e também são duas alterações morfológicas na estrutura do giro denteado após o status epilepticus (SE), nós hipotetizamos que as moléculas envolvidas no processo normal do desenvolvimento hipocampal também podem participar do processo de epileptogênese. MÉTODO: Utilizando hibridização in situ, caracterizamos a expressão do RNAm do fator de transcrição myocyte-specific enhancer binding factor 2C (MEF2C) no giro denteado durante o desenvolvimento (P0, P3, P7, P14 e P28) e em diferentes períodos após o SE (3, 7, 14, 28 dias após SE). RESULTADOS: Foi demonstrado um aumento da expressão de MEF2C no giro denteado durante o desenvolvimento e no giro denteado de animais adultos após o SE. CONCLUSÃO: As moléculas que controlam o destino celular durante o processo de desenvolvimento também estão operativas durante o processo de epileptogênese.