Fig. 2
From: Excessive fat expenditure in cachexia is associated with dysregulated circadian rhythm: a review
Dysregulated circadian rhythm is involved in lipid accumulation/lipolysis/utilization and thermogenesis in white and brown adipocytes by modulating enzymes involved in fat metabolism. The lipolysis and lipid storage of white adipocytes and thermogenesis of brown adipocytes are mediated by diurnal oscillations controlled by circadian rhythm, while dysregulated circadian rhythm may disrupt the circadian pattern in cachexia. Compared to that in the health condition, in the cachexia condition, the expression of adipogenesis genes, including Pparγ and C/EBPα, and the lipogenic genes Fas and Dgat decreased and lost rhythmicity in white adipocytes, indicating decreased lipid accumulation. In addition, the expression of lipases, such as ATGL, HSL and perilipin, and the thermogenesis gene Ucp-1 increased in white and brown adipocytes during both the day and night cycles, indicating increased lipolysis and lipid expenditure, compared with the expression in the health condition, in both the inactive and active phases. Pparγ transcriptional coregulator peroxisome proliferator-activated receptor gamma; C/EBPα CCAAT/enhancer-binding protein α; Fas fatty acid synthase; Dgat diacylglycerol O-acyltransferase; ATGL lipases adipose triglyceride lipase; HSL hormone‐sensitive lipase