Comparative effects of mitochondrial dysfunction in preadipocytes and in adipocytes. In preadipocytes, mitochondrial dysfunction induced by different factors such as hypoxia or mitochondrial respiration impairment (ie, using OXPHOS inhibitors) leads to impaired lipid metabolism and/or oxidation of lipids, proteins, and mtDNA, which trigger the accumulation of TGs in the cytosol of preadipocytes, a process mediated through a decrease in fatty acid β-oxidation and an increase in lipogenesis. Conversely, in adipocytes, mitochondrial dysfunction induced by factors such as HIV, HAART, aging, obesity, or T2DM leads to a decrease in ATP production, the development of insulin resistance, apoptosis, or impairment of adipogenesis. A moderate increase in cytosolic calcium concentration ([Ca2+]) results in the stimulation of lipogenesis and exerting an inhibitory effect on lipolysis accompanied by UCP-2 overexpression. All these effects lead to a decrease in triglyceride content mediated by a stimulation of lipolysis and a decrease in lipogenesis. POLγ, polymerase γ.
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