Breaking BAT: can browning create a better white?

Abstract

Obesity and its comorbidities are a growing problem worldwide. In consequence, several new strategies have been proposed to promote weight loss and improve insulin sensitivity.Recently, it has been demonstrated that certain populations of white adipocytes can be 'browned', i.e., recruited to a more brown-like adipocyte, capable of thermogenesis through increased expression of uncoupling protein 1. The list of browning agents that induce these so-called beige adipocytes is growing constantly. However, the underlying mechanisms are often poorly understood, with the possibility that some of these agents cause browning as a secondary effect. Moreover, it remains unclear whether beige adipocytes can contribute sufficiently to affect whole-body energy expenditure in a functionally significant manner. This review presents an overview of the different molecular pathways leading to the induction of beige fat, including direct stimulation and indirect actions on the CNS or the immune system. We discuss the available evidence on the capacity of beige adipocytes to influence whole-body energy expenditure in rodents, and lastly outline the potential problems of translating browning capacity into the potential treatment of human metabolic diseases.

Biliverdin Reductase A (BVRA) Knockout in Adipocytes Induces Hypertrophy and Reduces Mitochondria in White Fat of Obese Mice

“…Mitochondria play a vital role in the maintenance of adipocyte function. Strategies to increase the "browning" or "beiging" of adipose tissue, are now being considered as potential treatments for obesity [63][64][65]. In the present study, the loss of BVRA from WAT resulted in a reduction of mitochondria number.…”

Hydrogen Sulfide in the Adipose Tissue—Physiology, Pathology and a Target for Pharmacotherapy

“…These new brown adipocytes are called brite (brown-in-white) or beige fat cells [ 32 ]. Activity of existing BAT depots as well as WAT browning are stimulated by factors such as cold exposure, exercise, stimulation of sympathetic nervous system, thyroid hormones as well as several mediators including fibroblast growth factor-21 (FGF21), β-aminoisobutyric acid, bile acids, adenosine, melatonin and natriuretic peptides [ 33 , 34 , 35 , 36 ].…”

Liraglutide suppresses obesity and induces brown fat-like phenotype via Soluble Guanylyl Cyclase mediated pathwayin vivoandin vitro

“…WAT is characterized by a huge number of white adipocyte containing a large unilocular lipid droplet as well as few mitochondria, which is generally considered as insulation against cold and acts as the main site of metabolic energy storage in the form of TAG [38]. One feature of WAT browning is enhanced lipolysis [11], which is also known as the hydrolysis of TAG.…”