phenosys Publications
Large-scale two-photon calcium imaging in freely moving mice.

Abstract
Body weight is maintained through homeostatic mechanisms that balance energy intake and energy expenditure. To combat obesity, research has focused on activating thermogenesis, which accounts for 10%–15% of daily energy expenditure in humans but can expand to 30% with maximal activation (Ouellet et al., 2012). Adipocytes are central players in body weight maintenance and thermogenesis. There are three major types of adipocytes: white, beige, and brown. White adipocytes store excess energy and communicate the abundance of energy reserves to the whole body. Brown and beige adipocytes maintain body temperature through expression of uncoupling protein 1 (UCP1), which allows protons to flow into the mitochondrial matrix—harnessing the potential energy of the proton gradient as heat (Cohen and Kajimura, 2021). Brown adipose tissue is sequestered into a distinct depot along the spine, while beige adipocytes develop in subcutaneous white adipose tissue (sWAT). Recent research has focused on beige adipocytes because they function in adaptive thermogenesis (Shao et al., 2019). Most laboratory studies of beige thermogenesis have induced activity through prolonged cold exposure or pharmacological activation of β3-adrenergic receptors in mice. Both mechanisms are transient and require continuous stimuli (Weyer et al., 1998). Surprisingly, severe burn injury induces prolonged beige thermogenesis, which increases resting energy expenditure in humans (Patsouris et al., 2015). The burn-induced increase in UCP1 expression and mitochondrial content leads to whole body decreases in fat mass that can persist for at least 3 years post-burn. Any potential health advantages of weight loss are severely outweighed by the negative health effects of burn-induced hyperthermia, including increased circulating stress hormones, pro-inflammatory cytokines, and hyperglycemia that persist after wound healing and can lead to metabolic disease. Thus, it would be advantageous if the long-term benefits of sWAT beiging could be harnessed without the detrimental impact of burn injury.