Adipose mitochondrial membrane and mediates uncoupling of oxidative

Adipose tissues are placed in three major anatomical locations: subcutaneous, intraperitoneal and dermal. Adipose tissues contain adipocytes and stromal vascular cells. Humans along with all mammals have two major types of adipose tissue. White adipose tissue (WAT) regulates cumulation and hydrolysis of triglycerides. WAT influences body fat and energy utilization. Also, WAT has been associated with several crucial physiological pathways, such as glucose sensitivity and insulin sensitivity, through the production of lipids and adipocytokines. In adverse physiological condition, WAT is responsible for metabolic dysregulation which is related to insulin resistance, obesity-related metabolic and cardiovascular diseases. Brown adipose tissue (BAT) involves the regulation of adaptive thermogenesis. BAT exist in small rodents and mammalian newborns. BAT consists of adipocytes, which contain abundant multilocular lipid droplets. Brown adipocytes express a BAT-specific mitochondrial protein, uncoupling protein 1 (UCP1). UCP 1 is located on the inner mitochondrial membrane and mediates uncoupling of oxidative phosphorylation from ATP synthesis to thermogenesis. So far, researchers have shown that, in rodents, induction of BAT is related to abated adiposity and enhance insulin receptivity. Recently, experiments revealed that, in response to certain external stimulations depots of WAT could express BAT phenotypes. This process has been coined as “browning” of WAT. Yet now, based on research evidences some specific stimulations induce this browning process are as follows; 1. hormonal stimulation, such as irisin, released by skeletal muscle during exercise, 2. chronic cold exposure as physiological stimulation, and 3. pharmacological strategies like treatment with ?3?adrenergic receptor agonist or peroxisome proliferator-activated receptor (PPAR)-? agonists. These recruitable brown-like adipocytes have been named as, beige or brite adipocytes. Following external stimulations, beige adipocytes express the BAT-specific protein, UCP1 and express UCP1-dependent thermogenic regulation. Based on numerous studies, it has been established that, white and brown adipocytes have distinct developmental lineages. Even though there are some functional similarities between beige and brown adipocytes, in recent years, lineage-tracing experiments in transgenic mice revealed that, beige adipocytes emerge from Myf5 (myogenic factor 5)-negative cell lineage different from brown adipocytes, which arise from Myf5-positive cell lineage. Beige adipocytes also have shown discrete gene expression patterns compared to both white and brown adipocytes. However, the anatomical locations to categorize white, brown, beige adipocytes and the precise functions of them still remain obscure and need further investigation. 

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