RESUMEN
This study was performed to investigate the oxidative stress-induced miRNA changes in relation to pathogenesis of diabetic retinopathy (DR) and to establish a functional link between miRNAs and oxidative stress-induced retinal endothelial cell injury. Our results demonstrated that oxidative stress could induce alterations of miRNA expression profile, including up-regulation of miR-195 in the diabetic retina or cultured HMRECs after exposed to H2O2 or HG (P < 0.05). Oxidative stress also resulted in a significant reduction of MFN2 expression in diabetic retina or HMRECs (P < 0.05). Overexpression of miR-195 reduced MFN2 protein levels, and induced tube formation and increased permeability of diabetic retinal vasculature. The luciferase reporter assay confirmed that miR-195 binds to the 3' -untranslated region (3'-UTR) of MFN2 mRNA. This study suggested that miR-195 played a critical role in oxidative stress-induced retinal endothelial cell injury by targeting MFN2 in diabetic rats.
Asunto(s)
Diabetes Mellitus Experimental/metabolismo , Retinopatía Diabética/metabolismo , Proteínas de la Membrana/metabolismo , MicroARNs/metabolismo , Proteínas Mitocondriales/metabolismo , Estrés Oxidativo , Retina/metabolismo , Regiones no Traducidas 3' , Análisis de Varianza , Animales , Permeabilidad de la Membrana Celular , Supervivencia Celular/efectos de los fármacos , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/patología , Retinopatía Diabética/etiología , Retinopatía Diabética/patología , GTP Fosfohidrolasas , Expresión Génica/efectos de los fármacos , Células HEK293 , Células Endoteliales de la Vena Umbilical Humana , Humanos , Peróxido de Hidrógeno/metabolismo , Proteínas de la Membrana/genética , MicroARNs/genética , Proteínas Mitocondriales/genética , Ratas , Ratas Sprague-Dawley , Retina/patología , Regulación hacia ArribaRESUMEN
Abnormal gene expression, including mRNAs, and microRNAs (miRNA), have been identified in the development of Alzheimer's disease (AD). Although mitofusin2 (mfn2) has been found to be down-regulated in the neurons from hippocampus and cortex in AD patients, little is known about its roles and the regulatory mechanisms in the pathogenesis of AD. This study was performed to investigate the roles of mfn2 protein and its upstream regulatory mechanism in the progression of AD using a senescence accelerated mouse prone-8 (SAMP8) model. The results of quantitative real-time PCR and western blot revealed that mfn2 expression displayed a consistent decrease with aging in the hippocampus of SAMP8 than did age-matched SAMR1 mice. The luciferase activity assay combined with mutational analysis confirmed the binding site of miR-195 to the 3' -untranslated region (3'-UTR) of mfn2 mRNA. Furthermore, miR-195 inhibitor or antigomir induced the higher level expression of mfn2 protein in vitro and in vivo. In addition, exogenous expression of miR-195 decreased the mitochondrial membrane potential (MMP) of the HT-22 cells by targeting mfn2. In conclusion, these results indicated that deregulation of mfn2 might be involved in mitochondrial dysfunction during the progression of AD, and its decreased expression was regulated at least in part by miR-195 in AD mice. The abnormal expression of miR-195 played a potential role in mitochondrial disorder by targeting mfn2 in hippocampus of SAMP8 mice. Therefore, upregulation of mfn2 protein by inhibiting miR-195 might be a potential new therapeutic strategy for treatment of AD.