RESUMO
Alternative pre-mRNA-splicing-induced post-transcriptional gene expression regulation is one of the pathways for tumors maintaining proliferation rates accompanying the malignant phenotype under stress. Here, we uncover a list of hyperacetylated proteins in the context of acutely reduced Acetyl-CoA levels under nutrient starvation. PHF5A, a component of U2 snRNPs, can be acetylated at lysine 29 in response to multiple cellular stresses, which is dependent on p300. PHF5A acetylation strengthens the interaction among U2 snRNPs and affects global pre-mRNA splicing pattern and extensive gene expression. PHF5A hyperacetylation-induced alternative splicing stabilizes KDM3A mRNA and promotes its protein expression. Pathologically, PHF5A K29 hyperacetylation and KDM3A upregulation axis are correlated with poor prognosis of colon cancer. Our findings uncover a mechanism of an anti-stress pathway through which acetylation on PHF5A promotes the cancer cells' capacity for stress resistance and consequently contributes to colon carcinogenesis.
Assuntos
Processamento Alternativo , Carcinogênese/genética , Neoplasias Colorretais/genética , Regulação Neoplásica da Expressão Gênica , Histona Desmetilases com o Domínio Jumonji/genética , Proteínas de Ligação a RNA/genética , Transativadores/genética , Acetilcoenzima A/deficiência , Acetilação , Animais , Carcinogênese/metabolismo , Carcinogênese/patologia , Movimento Celular , Proliferação de Células , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Células HCT116 , Humanos , Histona Desmetilases com o Domínio Jumonji/antagonistas & inibidores , Histona Desmetilases com o Domínio Jumonji/metabolismo , Células MCF-7 , Masculino , Camundongos , Camundongos Nus , Prognóstico , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/antagonistas & inibidores , Proteínas de Ligação a RNA/metabolismo , Ribonucleoproteína Nuclear Pequena U2/genética , Ribonucleoproteína Nuclear Pequena U2/metabolismo , Transdução de Sinais , Análise de Sobrevida , Transativadores/antagonistas & inibidores , Transativadores/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto , Fatores de Transcrição de p300-CBP/genética , Fatores de Transcrição de p300-CBP/metabolismoRESUMO
Dendritic spine development is crucial for the establishment of excitatory synaptic connectivity and functional neural circuits. Alterations in spine morphology and density have been associated with multiple neurological disorders. Autism candidate gene disconnected-interacting protein homolog 2 A (DIP2A) is known to be involved in acetylated coenzyme A (Ac-CoA) synthesis and is primarily expressed in the brain regions with abundant pyramidal neurons. However, the role of DIP2A in the brain remains largely unknown. In this study, we found that deletion of Dip2a in mice induced defects in spine morphogenesis along with thin postsynaptic density (PSD), and reduced synaptic transmission of pyramidal neurons. We further identified that DIP2A interacted with cortactin, an activity-dependent spine remodeling protein. The binding activity of DIP2A-PXXP motifs (P, proline; X, any residue) with the cortactin-Src homology 3 (SH3) domain was critical for maintaining the level of acetylated cortactin. Furthermore, Dip2a knockout (KO) mice exhibited autism-like behaviors, including excessive repetitive behaviors and defects in social novelty. Importantly, acetylation mimetic cortactin restored the impaired synaptic transmission and ameliorated repetitive behaviors in these mice. Altogether, our findings establish an initial link between DIP2A gene variations in autism spectrum disorder (ASD) and highlight the contribution of synaptic protein acetylation to synaptic processing.
Assuntos
Acetilcoenzima A/genética , Transtorno do Espectro Autista/genética , Cortactina/genética , Espinhas Dendríticas/metabolismo , Morfogênese/genética , Proteínas Nucleares/genética , Processamento de Proteína Pós-Traducional , Acetilcoenzima A/deficiência , Acetilação , Motivos de Aminoácidos , Animais , Animais Recém-Nascidos , Transtorno do Espectro Autista/metabolismo , Transtorno do Espectro Autista/fisiopatologia , Sítios de Ligação , Cortactina/metabolismo , Espinhas Dendríticas/ultraestrutura , Modelos Animais de Doenças , Embrião de Mamíferos , Regulação da Expressão Gênica no Desenvolvimento , Teste de Complementação Genética , Camundongos , Camundongos Knockout , Proteínas Nucleares/deficiência , Densidade Pós-Sináptica/metabolismo , Densidade Pós-Sináptica/ultraestrutura , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Células Piramidais/metabolismo , Células Piramidais/ultraestrutura , Transmissão SinápticaRESUMO
The role of dietary iron supplementation in the development of nonalcoholic fatty liver disease (NAFLD) remains controversial. This study aimed to investigate the effect of excess dietary iron on NAFLD development and the underlying mechanism. Apolipoprotein E knockout mice were fed a chow diet, a high-fat diet (HFD), or an HFD containing 2% carbonyl iron (HFD + Fe) for 16 weeks. The serum and liver samples were acquired for biochemical and histopathological examinations. Isobaric tags for relative and absolute quantitation were performed to identify differentially expressed proteins in different groups. Excess dietary iron alleviated HFD-induced NAFLD, as evidenced by significant decreases in serum/the hepatic accumulation of lipids and the NAFLD scores in HFD + Fe-fed mice compared with those in HFD-fed mice. The hepatic acetyl-CoA level was markedly decreased in the HFD + Fe group compared with that in the HFD group. Important enzymes involved in the source and destination of acetyl-CoA were differentially expressed between the HFD and HFD + Fe groups, including the enzymes associated with cholesterol metabolism, glycolysis, and the tricarboxylic acid cycle. Furthermore, iron overload-induced mitochondrial dysfunction and oxidative stress occurred in mouse liver, as evidenced by decreases in the mitochondrial membrane potential and antioxidant expression. Therefore, iron overload regulates lipid metabolism by leading to an acetyl-CoA shortage that reduces cholesterol biosynthesis and might play a role in NAFLD pathogenesis. Iron overload-induced oxidative stress and mitochondrial dysfunction may impair acetyl-CoA formation from pyruvate and ß-oxidation. Our study provides acetyl-CoA as a novel perspective for investigating the pathogenesis of NAFLD.
Assuntos
Acetilcoenzima A , Sobrecarga de Ferro , Metabolismo dos Lipídeos , Hepatopatia Gordurosa não Alcoólica , Acetilcoenzima A/deficiência , Animais , Apolipoproteínas E/genética , Colesterol/metabolismo , Dieta Hiperlipídica/efeitos adversos , Sobrecarga de Ferro/metabolismo , Ferro da Dieta/metabolismo , Ferro da Dieta/farmacologia , Metabolismo dos Lipídeos/fisiologia , Fígado , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Hepatopatia Gordurosa não Alcoólica/metabolismoRESUMO
Several pathologic conditions are known to cause thiamine deficiency, which induce energy shortages in all tissues, due to impairment of pyruvate decarboxylation. Brain is particularly susceptible to these conditions due to its high rate of glucose to pyruvate-driven energy metabolism. However, cellular compartmentalization of a key energy metabolite, acetyl-CoA, in this pathology remains unknown. Pyrithiamine-evoked thiamine deficiency caused no significant alteration in pyruvate dehydrogenase and 30% inhibition of α-ketoglutarate dehydrogenase activities in rat whole forebrain mitochondria. It also caused 50% reduction of the metabolic flux of pyruvate through pyruvate dehydrogenase, 78% inhibition of its flux through α-ketoglutarate dehydrogenase steps, and nearly 60% decrease of intramitochondrial acetyl-CoA content, irrespective of the metabolic state. State 3 caused a decrease in citrate and an increase in α-ketoglutarate accumulation. These alterations were more evident in thiamine-deficient mitochondria. Simultaneously thiamine deficiency caused no alteration of relative, state 3-induced increases in metabolic fluxes through pyruvate and α-ketoglutarate dehydrogenase steps. These data indicate that a shortage of acetyl-CoA in the mitochondrial compartment may be a primary signal inducing impairment of neuronal and glial cell functions and viability in the thiamine-deficient brain.
Assuntos
Acetilcoenzima A/deficiência , Encéfalo/enzimologia , Mitocôndrias/enzimologia , Deficiência de Tiamina/enzimologia , Encefalopatia de Wernicke/enzimologia , Animais , Encéfalo/patologia , Modelos Animais de Doenças , Ativação Enzimática/fisiologia , Humanos , Masculino , Ratos , Ratos Wistar , Deficiência de Tiamina/patologia , Encefalopatia de Wernicke/patologiaRESUMO
Fatty acid oxidation disorders are among the most common inborn errors of metabolism affecting infants and children. Recognition of this family of defects is critical because careful dietary monitoring, avoidance of fasting, and prompt intervention during common childhood illness can prevent catastrophic cardiac and metabolic decompensation. This review focuses on new molecular and clinical diagnostic aspects of several of these disorders. Recent papers highlight the recognition that the clinical spectrum of disorders of fatty acid oxidation goes far beyond the stereotypical Reyes-like presentation or cardiomyopathy, and now encompasses more cases of sudden infant death syndrome, fulminant hepatic failure, and severe complications during pregnancy.
Assuntos
Ácidos Graxos/metabolismo , Erros Inatos do Metabolismo Lipídico/complicações , Hepatopatias/etiologia , Complicações na Gravidez/etiologia , Morte Súbita do Lactente/etiologia , Acetilcoenzima A/deficiência , Acetilcoenzima A/metabolismo , Carnitina/deficiência , Carnitina/metabolismo , Feminino , Doenças Fetais , Humanos , Lactente , Erros Inatos do Metabolismo Lipídico/diagnóstico , Erros Inatos do Metabolismo Lipídico/fisiopatologia , Masculino , Oxirredução , GravidezRESUMO
Considerable debate surrounds the identity of the precise cellular site(s) of inertia that limit the contribution of mitochondrial ATP resynthesis towards a step increase in workload at the onset of muscular contraction. By detailing the relationship between canine gracilis muscle energy metabolism and contractile function during constant-flow ischaemia, in the absence (control) and presence of pyruvate dehydrogenase complex activation by dichloroacetate, the present study examined whether there is a period at the onset of contraction when acetyl-coenzyme A (acetyl-CoA) availability limits mitochondrial ATP resynthesis, i.e. whether a limitation in mitochondrial acetyl group provision exists. Secondly, assuming it does exist, we also aimed to identify the mechanism by which dichloroacetate overcomes this "acetyl group deficit". No increase in pyruvate dehydrogenase complex activation or acetyl group availability occurred during the first 20 s of contraction in the control condition, with strong trends for both acetyl-CoA and acetylcarnitine to actually decline (indicating the existence of an acetyl group deficit). Dichloroacetate increased resting pyruvate dehydrogenase complex activation, acetyl-CoA and acetylcarnitine by approximately 20-fold (P < 0.01), approximately 3-fold (P < 0.01) and approximately 4-fold (P < 0.01), respectively, and overcame the acetyl group deficit at the onset of contraction. As a consequence, the reliance upon non-oxidative ATP resynthesis was reduced by approximately 40 % (P < 0.01) and tension development was increased by approximately 20 % (P < 0.05) following 5 min of contraction. The present study has demonstrated, for the first time, the existence of an acetyl group deficit at the onset of contraction and has confirmed the metabolic and functional benefits to be gained from overcoming this inertia.