• BMB Reports
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• v.52 no.9
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• pp.566-571
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• 2019

Lymphoma is one of the most curable types of cancer. However, drug resistance is the main challenge faced in lymphoma treatment. Peroxisomal acyl-CoA oxidase 1 (ACOX1) is the rate-limiting enzyme in fatty acid ${\beta}$-oxidation. Deregulation of ACOX1 has been linked to peroxisomal disorders and carcinogenesis in the liver. Currently, there is no information about the function of ACOX1 in lymphoma. In this study, we found that upregulation of ACOX1 promoted proliferation in lymphoma cells, while downregulation of ACOX1 inhibited proliferation and induced apoptosis. Additionally, overexpression of ACOX1 increased resistance to doxorubicin, while suppression of ACOX1 expression markedly potentiated doxorubicin-induced apoptosis. Interestingly, downregulation of ACOX1 promoted mitochondrial location of Bad, reduced mitochondrial membrane potential and provoked apoptosis by activating caspase-9 and caspase-3 related apoptotic pathway. Overexpression of ACOX1 alleviated doxorubicin-induced activation of caspase-9 and caspase-3 and decrease of mitochondrial membrane potential. Importantly, downregulation of ACOX1 increased p73, but not p53, expression. p73 expression was critical for apoptosis induction induced by ACOX1 downregulation. Also, overexpression of ACOX1 significantly reduced stability of p73 protein thereby reducing p73 expression. Thus, our study indicated that suppression of ACOX1 could be a novel and effective approach for treatment of lymphoma.

• Biomedical Science Letters
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• v.16 no.4
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• pp.239-246
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• 2010

It is suggested that ovariectomy induces body weight gain primarily in the form of adipose tissue in rodents. Since liver peroxisome proliferator-activated receptor ${\alpha}$ (PPAR${\alpha}$) and uncoupling 2 (UCP2) are involved in the regulation of energy expenditure, it was investigated whether swim training regulates ovariectomy-induced adiposity and steatosis through liver PPAR${\alpha}$ and UCP2 activation in female ovariectomized mice, an animal model of postmenopausal women. Swim-trained mice had significantly decreased adipose tissue weights compared with sedentary control mice. Histological analysis showed that hepatic lipid accumulation was inhibited by swim training. Concomitantly, swim training significantly increased mRNA levels of PPAR${\alpha}$ and its target genes responsible for peroxisomal fatty acid ${\beta}$-oxidation, such as acyl-CoA oxidase, enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase and thiolase in the liver. Moreover, swim training induced the mRNA expression of UCP2. These results suggest that swim training can effectively prevent adiposity and steatosis caused by ovariectomy, in part through activation of liver PPAR${\alpha}$ and UCP2 in female obese mice.

• Archives of Pharmacal Research
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• v.21 no.2
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• pp.120-127
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• 1998

Peroxisome proliferators induce hepatic peroxisome proliferation and hepatic tumors in rodents. These chemicals increase the expression of the peroxisomal $\beta$-oxidation pathway and the cytochrome P-450 4A family, which metabolizes lipids, including eicosanoids. Peroxisome proliferators transiently induce increased cell proliferation in vivo. However, peroxisome proliferators are weakly mitogenic and are not co-mitogenic with epidermal growth factor (EGF) in cultured hepatocytes. Earlier study found that the peroxisome proliferator ciprofibrate is cornitogenic with eicosanoids. In order to study possible mechanisms of the comitogenicity of peroxisome proliferator ciprofibrate and eicosanoids' we hypothesized that the co-mitogenicity may result from synergistic or additive increases of second messengers in mitogenic signal pathways. We therefore examined the effect of the peroxisome proliferator ciprofibrate, prostaglandin $F_2_{\alpha}$($PGF_2{\alpha}$) and the combination of ciprofibrate and $PGF_2{\alpha}$ with or without growth factors on the protein kinase C (PKC) activity, and inositol-1, 4, 5-triphosphate ($IP_{3-}$) and intracellular calcium ($[Ca^{2+}]_i$) concentrations in cultured rat hepatocytes. The combination of ciprofibrate and $PGF_2{\alpha}$ significantly increased particulate PKC activity. The combination of ciprofibrate and $PGF_2{\alpha}$ also significantly increased EGF, transforming growth factor-$\alpha$ ($TGF_2{\alpha}$) and hepatic growth factor (HGF)-induced particulate PKC activity. The combination of ciprofibrate and $PGF_2_\alpha$greatly increased $[Ca^{2+}]_i$. However, the increases of PKC activity and $[Ca^{2+}]_i$ by ciprofibrate and $PGF_2{\alpha}$ alone were much smaller. Neither ciprofibrate or $PGF_2{\alpha}$ alone nor the combination of ciprofibrate and $PGF_2{\alpha}$ significantly increased the formation of $IP_3$. The combination of ciprofibrate and $PGF_2{\alpha}$, however, blocked the inhibitory effect of $TGF-{\beta}$ on particulate PKC activity and formation of $IP_3$ induced by EGF. These results show that co-mitogenicity of the peroxisome proliferator ciprofibrate and eicosanoids may result from the increase in particulate PKC activity and intracellular calcium concentration but not from the formation of $IP_3$.

• Molecules and Cells
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• v.23 no.2
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• pp.161-169
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• 2007

We identified two alternatively spliced variants of the peroxisomal targeting signal 1 (PTS1) receptor protein Pex5ps in monocot (rice, wheat, and barley) but not in dicot (Arabidopsis and tobacco) plants. We characterized the molecular and functional differences between the rice (Oryza sativa) Pex5 splicing variants OsPex5pL and OsPex5pS. There is only a single-copy of OsPEX5 in the rice genome and RT-PCR analysis points to alternative splicing of the transcripts. Putative light-responsive cis-elements were identified in the 5' region flanking OsPEX5L and Northern blot analysis demonstrated that this region affected light-dependent expression of OsPEX5 transcription. Using the pex5-deficient yeast mutant Scpex5, we showed that OsPex5pL and OsPex5pS are able to restore translocation of a model PTS1 protein (GFP-SKL) into peroxisomes. OsPex5pL and OsPex5pS formed homo-complexes via specific interaction domains, and interacted with each other and OsPex14p to form hetero-complexes. Although overexpression of OsPex5pL in the Arabidopsis pex5 mutant (Atpex5) rescued the mutant phenotype, overexpression of OsPex5pS only resulted in partial recovery.

• Molecules and Cells
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• v.37 no.1
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• pp.74-80
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• 2014

The peroxisome is an intracellular organelle that responds dynamically to environmental changes. Various model organisms have been used to study the roles of peroxisomal proteins in maintaining cellular homeostasis. By taking advantage of the zebrafish model whose early stage of embryogenesis is dependent on yolk components, we examined the developmental roles of the D-bifunctional protein (Dbp), an essential enzyme in the peroxisomal ${\beta}$-oxidation. The knockdown of dbp in zebrafish phenocopied clinical manifestations of its deficiency in human, including defective craniofacial morphogenesis, growth retardation, and abnormal neuronal development. Overexpression of murine Dbp rescued the morphological phenotypes induced by dbp knockdown, indicative of conserved roles of Dbp during zebrafish and mammalian development. Knockdown of dbp impaired normal development of blood, blood vessels, and most strikingly, endoderm-derived organs including the liver and pancreas - a phenotype not reported elsewhere in connection with peroxisome dysfunction. Taken together, our results demonstrate for the first time that zebrafish might be a useful model animal to study the role of peroxisomes during vertebrate development.

• Journal of Nutrition and Health
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• v.28 no.4
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• pp.268-281
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• 1995

This study was undertaken to elucidate the effect of DHA-rich fish oil (DHA-rich oil) added to different dietary fats on lipid metabolism. Rats were fed perilla oil, sesame oil and beef tallow with or without DHA-rich oil for 12 weeks. The weight gain was higher in groups with DHA-rich oil than that of groups without DHA-rich oil, with DHA-rich oil, while weight of epididymal fat pad was lower in perilla oil and beef tallow groups with DHA-rich oil. The contents of total lipid and triglyceride in plasma were not affected by dietary fat types, but that of total and HDL cholesterol in plasma were higher in sesame oil group than perilla oil and beef tallow groups without DHA-rich oil. The contents of total lipid, triglyceride, total cholesterol, HDL cholestrol and LDL cholesterol in plasma were decreased by DHL-rich oil addition. The contents of total lipid, total cholesterol and triglyceride in the liver were not affected by dietary fat type. The contents of total cholesterol and triglyceride in the liver were not affected by dietary fat type. The contents of total lipid and TG in liver were not affected by DHA-rich oil addition while hepatic cholesterol increased by DHA-rich oil addition. The activities of glucose 6-phosphate dehydrogenase and malic enzyme were highest in beef tallow group without DHA-rich oil and decreased by DHA-rich oil addition. Peroxisomal ${\beta}$-oxidation had an inverse relationship against the activities of lipogenic enzymes. In conclusion, dietary DHA-rich oil decreased fat accumulation and had hypolipidemic effect, especially in beef tallow group. Also groups with DHA-rich oil showed more hypolipidemic effect than perilla oil group. And DHA-rich oil addition to diets resulted in increasing dietary n-3/n-6 ratio. Therefore increase in n-3/n-6 ratio as well as dietary DHA were considered to be responsible for the hypolipidemic effect resulted from DHA-rich oil addition.