| dc.description.abstract | Di(2-ethylhexyl) phthalate (DEHP) is widely used in industry to increase the malleability of polyvinyl chloride. It can be found in plastic package, toys, clinic, cosmetic, building, and so on. Once entered the body, it is quickly metabolized to MEHP. Previous studies have shown that the level of phthalate is associated with the development of type-2 diabetes and insulin resistance. In this study, the effects of MEHP on myogenic differentiation, the metabolism of glucose and fatty acid oxidation, and mitochondrial function were observed. We treated C2C12 cells with 100 μM MEHP for two days and cells treated with MEHP in the proliferation stage during myogenesis failed to form myotubes. After three days of differentiation, MEHP treatment did not influence differentiation, we used this stage for measuring the effects of MEHP on metabolism so the intereference from differentiation could be avoided. First, we measured glucose uptake, in the stimulation of insulin situation, MEHP group caused the cells to absorb less glucose compared to the DMSO group. Moreover, we investigated the metabolism of glucose and fatty acid oxidation by using Real-time PCR. The gene expression of ERRα、PDK4、CPT1B is up-regulated. Second, we observed the effect of MEHP on mitochondrial function. C2C12-MTS-RFP was culture for three days in CMB stage, then treated with MEHP for two days and checked the mitochondrial morphology. The cells tended to become fission as compared to the DMSO group. It probably had poor function in mitochondria. So we checked the content of mitochondria. MITO DNA and the gene expression of Tfam was not affected by MEHP. To investigate the function of mitochondria, a series assays on the functions of electron transport system was measured. Membrane potential was not influenced by MEHP, while succinate dehydrogenase was decreased and produced ROS then enhance SOD activity. The expression of ROS-related gene HO-1 was significantly up-regulated. Third, we measured the protein level of 5 complexes in the electron transport system. In the myotube stage, treatment with MEHP decreased the lelvel of complex I subunit-Ndufb8. To ensure whether MEHP influenced transcription or translation stage, mRNA level and promoter activity were measured, and we found MEHP did not influence the transcription of Ndufb8. Through adding translation inhibitor cycloheximide in the medium, we found MEHP might interfere with the translation of Ndufb8. Taken together, MEHP can affect the function of mitochondria and by affecting the functions/levels of key factors in the ETC system. | en_US |