Regulation of Brown Versus White Adipogenesis; Mode of Action and Regulatory Mechanism

Abstract

Mammalian adipose tissue is comprised of two main types of adipocytes, white and brown, which inversely contribute to energy balance regulation. White adipocytes possess a large unilocular lipid droplet, reside in white adipose tissue (WAT), and store excess energy as fat. Brown adipocytes, on the other hand, possess a multilocular appearance (multiple small lipids droplets), reside in brown adipose tissue (BAT), consume energy reserves, and produce heat. Brown adipocytes have an enormous capacity for substrate oxidation conferred by a very high abundance of mitochondria. These mitochondria are equipped with uncoupling protein 1 (UCP1), a 32 kDa protein residing in the inner mitochondrial membrane. When activated by sympathetic nerves that control the lipolytic release of activating fatty acids and the degradation of inhibitory purine nucleotides. White adipocytes possess a large unilocular lipid droplet, reside in white adipose tissue (WAT), and store excess energy as fat. Brown adipocytes, on the other hand, possess a multilocular appearance (multiple small lipids droplets), reside in brown adipose tissue (BAT), consume energy reserves, and produce heat.UCP1 induces a proton leak that uncouples oxygen consumption from ATP production, facilitating macronutrient catabolism. This adaptive mechanism increases energy expenditure and makes BAT an important heater organ, especially in small mammals,there are several factors associated with the formation of brown fat cells such as PGC1α, CIDEA, PRDM16, PPar1α and so on.