RESUMO
Hyperglycemia, a diagnostic characteristic of diabetes mellitus, is detrimental to pancreatic ß cells. Delphinidin, a member of the anthocyanin family, inhibits glucose absorption, increases glucagon-like peptide-1 (GLP-1) secretion, and improves insulin secretion in diabetes. However, whether delphinidin plays a protective role in pancreatic ß-cell mass and function is not clear. In this study, delphinidin was found to decrease the high-glucose-induced apoptosis of RIN-m5F pancreatic ß cells. In addition, delphinidin induced autophagy in RIN-m5F cells under the normal and high-glucose conditions, while 3-methyladenine (3-MA) inhibition of autophagy significantly diminished the protective role of delphinidin against high-glucose-induced apoptosis of pancreatic ß cells. Delphinidin also decreased the level of cleaved caspase 3 and increased the phosphorylation level of AMP-activated protein kinase α (AMPKα) Thr172. Compound C, an AMPK inhibitor, was found to decrease the ratio of LC3-II/LC3-I, and the apoptotic rate of high-glucose-injured cells was increased after treatment with delphinidin, indicating that delphinidin attenuated the negative effects of high-glucose stress to cells. In conclusion, our data demonstrate that delphinidin protects pancreatic ß cells against high-glucose-induced injury by autophagy regulation via the AMPK signaling pathway. These findings might shed light on the underlying mechanisms of diabetes and help improve the prevention and therapy of this common disease.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Antocianinas/farmacologia , Glucose/metabolismo , Células Secretoras de Insulina/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Animais , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Linhagem Celular , Células Secretoras de Insulina/citologiaRESUMO
Momordica grosvenori is a valuable edible plant with medicinal purposes, and it is widely used in medicated diets and traditional Chinese medicine in Asia. Mogroside V (MV), the main bioactive component from M. grosvenori, is commonly used as a natural sweetener. M. grosvenori extracts have been reported to exert potent anti-inflammatory property, however the underlying molecular mechanism still remains unknown. In the present study, the biological effect of MV in inflammation was investigated in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The ELISA and western blot analysis results showed that MV significantly inhibited LPS-induced prostaglandin E2 (PGE2) production and cyclooxygenase-2 (COX-2) expression. MV markedly decreased the phosphorylation of IκB-α, increased IκB-α, and reduced nuclear p-65 and C/EBPδ. Furthermore, MV attenuated LPS-induced phosphorylation of MAPKs and AKT1, and only the phosphorylation status of AKT1 was found to be consistent with the expression trend of COX-2. Moreover, MV reduced ROS level and restored overexpressed HO-1 and AP-1 to basal level, which can be markedly reversed by AKT1 inhibitor LY294002. These results revealed that AKT1 plays a key role in LPS-induced COX-2 expression, and acts as a mediator to keep the redox balance in LPS-stimulated RAW264.7 cells. MV exerts anti-inflammatory property by blocking AKT1-mediated NF-κB and C/EBPδ activation, ROS generation and AP-1/ HO-1 expression. Therefore, the present study indicated that MV has a significant chemopreventive effect on the inflammatory lesions and suggested that AKT1 is a potential specific target of MV for relieving inflammation.
Assuntos
Ciclo-Oxigenase 2/genética , Heme Oxigenase-1/genética , Lipopolissacarídeos/farmacologia , Macrófagos/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Triterpenos/farmacologia , Animais , Ciclo-Oxigenase 2/metabolismo , Dinoprostona/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Heme Oxigenase-1/metabolismo , Macrófagos/citologia , Macrófagos/metabolismo , Camundongos , Estrutura Molecular , Momordica/química , Fosforilação/efeitos dos fármacos , Células RAW 264.7 , Triterpenos/químicaRESUMO
Gymnemic acid I (GA I) is a bioactive component of Gymnema sylvestre. It is an Indian traditional medicinal herb which has antidiabetic effect. However, the molecular mechanism is remaining to be elucidated. Here, we showed that high glucose promoted the rate of apoptosis, GA I decreased the apoptosis under the high glucose stress. Our further study explored that GA I increased the number of autophagosome and the ratio of light chain 3-I (LC3-I)/LC3-II in MIN-6 cells under the normal or high glucose stress by the methods of western blot analysis and immunofluorescence. It induced autophagy flux and inhibited the phosphorylation of mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase ß-1 (p70 S6K/S6K1), which is a substrate of mTOR. GA I decreased the rate of apoptosis and the activity of caspase-3 under the high glucose stress. The inhibition of apoptosis and caspase-3 activity by GA I were increased after treating with autophagy inhibitor in mouse islet ß cells MIN-6. Our data suggested that GA I-induced autophagy protected MIN-6 cells from apoptosis under high glucose stress via inhibition the phosphorylation activity of mTOR.