RESUMO
Cerebral ischemia/reperfusion (I/R) injury is a leading cause of learning and memory dysfunction. Hydrogen sulfide (H2S) has been shown to confer neuroprotection in various neurodegenerative diseases, including cerebral I/R-induced hippocampal CA1 injury. However, the underlying mechanisms have not been completely understood. In the present study, rats were pretreated with SAM/NaHS (SAM, an H2S agonist, and NaHS, an H2S donor) only or SAM/NaHS combined with CaM (an activator of CaMKII) prior to cerebral ischemia. The Morris water maze test demonstrated that SAM/NaHS could alleviate learning and memory impairment induced by cerebral I/R injury. Cresyl violet staining was used to show the survival of hippocampal CA1 pyramidal neurons. SAM/NaHS significantly increased the number of surviving cells, whereas CaM weakened the protection induced by SAM/NaHS. The immunohistochemistry results indicated that the number of Iba1-positive microglia significantly increased after cerebral I/R. Compared with the I/R group, the number of Iba1-positive microglia in the SAM/NaHS groups significantly decreased. Co-Immunoprecipitation and immunoblotting were conducted to demonstrate that SAM/NaHS suppressed the assembly of CaMKII with the ASK1-MKK3-p38 signal module after cerebral I/R, which decreased the phosphorylation of p38. In contrast, CaM significantly inhibited the effects of SAM/NaHS. Taken together, the results suggested that SAM/NaHS could suppress cerebral I/R injury by downregulating p38 phosphorylation via decreasing the assembly of CaMKII with the ASK1-MKK3-p38 signal module.
Assuntos
Região CA1 Hipocampal/efeitos dos fármacos , Calmodulina/farmacologia , Sulfeto de Hidrogênio/metabolismo , AVC Isquêmico/metabolismo , Transtornos da Memória/metabolismo , Traumatismo por Reperfusão/metabolismo , S-Adenosilmetionina/farmacologia , Sulfetos/farmacologia , Animais , Região CA1 Hipocampal/metabolismo , Região CA1 Hipocampal/patologia , Proteínas de Ligação ao Cálcio/efeitos dos fármacos , Proteínas de Ligação ao Cálcio/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/efeitos dos fármacos , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Regulação para Baixo , AVC Isquêmico/fisiopatologia , Aprendizagem/efeitos dos fármacos , MAP Quinase Quinase 3/efeitos dos fármacos , MAP Quinase Quinase 3/metabolismo , MAP Quinase Quinase Quinase 5/efeitos dos fármacos , MAP Quinase Quinase Quinase 5/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Transtornos da Memória/fisiopatologia , Proteínas dos Microfilamentos/efeitos dos fármacos , Proteínas dos Microfilamentos/metabolismo , Microglia/efeitos dos fármacos , Microglia/metabolismo , Microglia/patologia , Teste do Labirinto Aquático de Morris , Fosforilação , Células Piramidais/efeitos dos fármacos , Células Piramidais/metabolismo , Ratos , Traumatismo por Reperfusão/fisiopatologia , Proteínas Quinases p38 Ativadas por Mitógeno/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Muscle atrophy is a debilitating process associated with many chronic wasting diseases, like cancer, diabetes, sepsis, and renal failure. Rapid loss of muscle mass occurs mainly through the activation of protein breakdown by the ubiquitin proteasome pathway. Foxo3a transcription factor is critical for muscle atrophy, since it activates the expression of ubiquitin ligase Atrogin-1. In several models of atrophy, inhibition of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway induces nuclear import of Foxo3a through an Akt-dependent process. This study aimed to identify signaling pathways involved in the control of Foxo3a nuclear translocation in muscle cells. We observed that after nuclear import of Foxo3a by PI3K/Akt pathway inhibition, activation of stress-activated protein kinase (SAPK) pathways induced nuclear export of Foxo3a through CRM1. This mechanism involved the c-Jun NH(2)-terminal kinase (JNK) signaling pathway and was independent of Akt. Likewise, we showed that inhibition of p38 induced a massive nuclear relocalization of Foxo3a. Our results thus suggest that SAPKs are involved in the control of Foxo3a nucleocytoplasmic translocation in C2C12 cells. Moreover, activation of SAPKs decreases the expression of Atrogin-1, and stable C2C12 myotubes, in which the p38 pathway is constitutively activated, present partial protection against atrophy.