• The Korean Journal of Physiology and Pharmacology
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• v.21 no.3
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• pp.317-325
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• 2017

Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent liver disease in parallel with worldwide epidemic of obesity. Reactive oxygen species (ROS) contributes to the development and progression of NAFLD. Peroxisomes play an important role in fatty acid oxidation and ROS homeostasis, and catalase is an antioxidant exclusively expressed in peroxisome. The present study examined the role of endogenous catalase in early stage of NAFLD. 8-week-old male catalase knock-out (CKO) and age-matched C57BL/6J wild type (WT) mice were fed either a normal diet (ND: 18% of total calories from fat) or a high fat diet (HFD: 60% of total calories from fat) for 2 weeks. CKO mice gained body weight faster than WT mice at early period of HFD feeding. Plasma triglyceride and ALT, fasting plasma insulin, as well as liver lipid accumulation, inflammation (F4/80 staining), and oxidative stress (8-oxo-dG staining and nitrotyrosine level) were significantly increased in CKO but not in WT mice at 2 weeks of HFD feeding. While phosphorylation of Akt (Ser473) and $PGC1{\alpha}$ mRNA expression were decreased in both CKO and WT mice at HFD feeding, $GSK3{\beta}$ phosphorylation and Cox4-il mRNA expression in the liver were decreased only in CKO-HF mice. Taken together, the present data demonstrated that endogenous catalase exerted beneficial effects in protecting liver injury including lipid accumulation and inflammation through maintaining liver redox balance from the early stage of HFD-induced metabolic stress.

• Molecules and Cells
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• v.39 no.7
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• pp.543-549
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• 2016

MicroRNAs (miRNAs) have been reported to be involved in many neurodegenerative diseases. The present study focused on the role of hsa-miR-144-3p in one of the neuro-degenerative diseases, Parkinson's disease (PD). Our study showed a remarkable down-regulation of miR-144-3p expression in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-treated SH-SY5Y cells. MiR-144-3p was then overexpressed and silenced in human SH-SY5Y cells by miRNA-mimics and miRNA-inhibitor transfections, respectively. Furthermore, ${\beta}$-amyloid precursor protein (APP) was identified as a target gene of miR-144-3p via a luciferase reporter assay. We found that miR-144-3p overexpression significantly inhibited the protein expression of APP. Since mitochondrial dysfunction has been shown to be one of the major pathological events in PD, we also focused on the role of miR-144-3p and APP in regulating mitochondrial functions. Our study demonstrated that up-regulation of miR-144-3p increased expression of the key genes involved in maintaining mitochondrial function, including peroxisome proliferator-activated receptor ${\gamma}$ coactivator-$1{\alpha}$(PGC-$1{\alpha}$), nuclear respiratory factor 1 (NRF-1) and mitochondrial transcription factor A (TFAM). Moreover, there was also a significant increase in cellular ATP, cell viability and the relative copy number of mtDNA in the presence of miR-144-3p overexpression. In contrast, miR-144-3p silencing showed opposite effects. We also found that APP overexpression significantly decreased ATP level, cell viability, the relative copy number of mtDNA and the expression of these three genes, which reversed the effects of miR-144-3p overexpression. Taken together, these results show that miR-144-3p plays an important role in maintaining mitochondrial function, and its target gene APP is also involved in this process.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.3
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• pp.283-289
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• 2015

This study surveys the improvement characteristics in old-aged muscular mitochondria by bio-active materials coated fabric (BMCF). To observe the effects, the fabric (10 and 30%) was worn to old-aged rat then the oxygen consumption efficiency and copy numbers of mitochondria, and mRNA expression of apoptosis- and mitophagy-related genes were verified. By wearing the BMCF, the oxidative respiration significantly increased when using the 30% materials coated fabric. The mitochondrial DNA copy number significantly decreased and subsequently recovered in a dose-dependent manner. The respiratory control ratio to mitochondrial DNA copy number showed a dose-dependent increment. As times passed, Bax, caspase 9, PGC-$1{\alpha}$ and ${\beta}$-actin increased, and Bcl-2 decreased in a dose-dependent manner. However, the BMCF can be seen to have had no effect on Fas receptor. PINK1 expression did not change considerably and was inclined to decrease in control group, but the expression was down-regulated then subsequently increased with the use of the BMCF in a dose-dependent manner. Caspase 3 increased and subsequently decreased in a dose-dependent manner. These results suggest that the BMCF invigorates mitophagy and improves mitochondrial oxidative respiration in skeletal muscle, and in early stage of apoptosis induced by the BMCF is not related to extrinsic death-receptor mediated but mitochondria-mediated signaling pathway.