RESUMO
This study is to investigate the underlying mechanisms of mitochondrial quality control (MQC) regulated by HtrA2/Omi during ischemia/reperfusion (I/R). We utilized the mnd2 mouse model, which has a missense mutation in HtrA2/Omi, to investigate the HtrA2/Omi regulation in mitochondria after I/R injury in the cerebral cortex. Compared to homozygous (HtrA2mnd2) mice, heterozygous (HtrA2Hetero) mice showed aging signs at a later age, increased HtrA2/Omi expression in the brain cortex, and lesser neurodegenerative signs. The brain cortex of HtrA2Hetero mice had increased superoxide dismutase (SOD) activity; lower levels of malondialdehyde (MDA); higher expressions of mitochondrial unfolded protein response (mtUPR)-related proteins, NADH dehydrogenase [ubiquinone] iron-sulfur protein 7 (Ndufs7), and uncoupling protein 2 (UCP2) proteins; more mitochondrial fission; higher levels of ATP and mtDNA copies; elevated sirtuin 3 (SIRT3) activity; and increased NAD+/NADH ratio. After 1.5 h of I/R, the brain cortex of HtrA2Hetero mice had a larger infarction size, reduced HtrA2/Omi expression, decreased S-X-linked inhibitor of apoptosis protein (XIAP), and increased C-Caspase3 than that of wild-type animals (WT). Mitochondria from the HtrA2Hetero brain cortex showed decreased ATP production and MQC deficiency after 1.5 h I/R. Genipin pre-treatment reduced the aforementioned I/R injury in the HtrA2Hetero brain cortex. In conclusion, mitochondrial function is compensated in the HtrA2Hetero brain cortex via the upregulation of the UCP2-SIRT3-PGC1 axis. Decreased HtrA2/Omi function damages mitochondrial quality in the HtrA2Hetero mouse brain cortex, leading to more brain I/R injury. Genipin pre-treatment ameliorates brain damages via the mitochondrial UCP2-SIRT3-PGC1 axis.
Assuntos
Reprogramação Celular/genética , Córtex Cerebral/metabolismo , Serina Peptidase 2 de Requerimento de Alta Temperatura A/fisiologia , Hipóxia Encefálica/genética , Hipóxia Encefálica/metabolismo , Mitocôndrias/genética , Mitocôndrias/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/metabolismo , Sirtuína 3/metabolismo , Proteína Desacopladora 2/metabolismo , Animais , Modelos Animais de Doenças , Camundongos TransgênicosRESUMO
Neurodegenerative diseases are disorders that are characterized by a progressive decline of motor and/or cognitive functions caused by the selective degeneration and loss of neurons within the central nervous system. The most common neurodegenerative diseases are Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Neurons have high energy demands, and dysregulation of mitochondrial quality and function is an important cause of neuronal degeneration. Mitochondrial quality control plays an important role in maintaining mitochondrial integrity and ensuring normal mitochondrial function; thus, defects in mitochondrial quality control are also significant causes of neurodegenerative diseases. The mitochondrial deacetylase SIRT3 has been found to have a large effect on mitochondrial function. Recent studies have also shown that SIRT3 has a role in mitochondrial quality control, including in the refolding or degradation of misfolded/unfolded proteins, mitochondrial dynamics, mitophagy, and mitochondrial biogenesis, all of which are affected in neurodegenerative diseases.
