7097 The role of mitochondrial fraction locating cytoplasmic and peridroplet area in white adipocyte

Abstract Disclosure: I. Mori: None. T. Ishizuka: None. H. Morita: None. K. Kajita: None. White adipocytes (WAs) are involved in the formation of obesity and insulin resistance, but little is known about the role of WAs mitochondria. A recent study revealed that the mitochondria of brown adipocytes (BAs) consist of cytoplasmic mitochondria CM), which is responsible for β-oxidation, and peridroplet mitochondria (PDM), which supplies triglyceride to lipid droplets. However, it is unclear whether such a functional division exist in WA mitochondria. In this study, we examined whether the pellets obtained from cytoplasmic and oil layers of WAs of C57/BL/J mice by centrifugation were mitochondria. Since mitochondrial DNA, mitochondrial protein, Mitotracker Red staining, and mitochondrial images in electron microscope were detected in both fractions, they were considered to be cytoplasmic mitochondria (CMw) and peridroplet mitochondria (PDMw) in WAs, respectively. The amount of CMw and PDMw were greater in epididymal fat than in inguinal fat. CMw had higher β-oxidation activity than PDMw. PDMw was associated with perilipin 1/3 and diacylglycerol acyltransferase 2. The amount of PDMw was elevated in epididymal fat of mice fed a high-fat diet (HFD) for 2 and 4 weeks compared to normal chew-fed mice. These results suggested that CMw was involved in β-oxidation, and PDMw in droplet expansion. Although numerous researches have been shown that amount of mitochondria is suppressed in obese WAs, our results revealed that PDMw might be involved in the early stage of obesity formation. Presentation: 6/1/2024