Can Brown Fat Win the Battle Against White Fat?

Abstract

A rapid growth in the overweight and obese population in the last few decades suggest that the current diet, exercise, awareness or drug strategies are still not effectively restraining the obesity epidemic. Obesity results from increased energy intake, and the body’s energy balance shifts towards energy abundance. Therefore, current research is focused on developing new strategies aimed at increasing energy expenditure. As a result, brown adipose tissue (BAT) is receiving tremendous attention since the major function of BAT is to dissipate energy as heat. For example, mouse models that have increased BAT activity or increased numbers of brown-like adipocytes within the white adipose tissue (WAT) are lean and protected from obesity. Alternatively, mouse models that lack BAT activity are more susceptible to age and diet-induced obesity. However, a significant loss of BAT mass during the natural growth process in humans has created enormous challenges in effectively utilizing this tissue to increase energy expenditure. New strategies are primarily focused on expanding the BAT mass and/or activating the existing BAT. In this regard, recent finding that expression of early B cell factor-2 (Ebf2) reprograms the white pre-adipocytes into brown adipocytes is a significant break-through in developing BAT-mediated strategies to treat obesity. Here we review the major biological functions of WAT and BAT, which play critical but opposing roles in the energy spectrum, energy storage versus energy expenditure, and we evaluate whether activation and/or expansion of BAT is practically achievable to treat obesity in humans.

Nonspecific Energy Expenditure of the Body and Body Mass Regulation

“…The uncoupling action of Sln is functionally linked to its N-terminal amino acid residue. Removal of this residue from the structure of Sln deprives it of uncoupling and thermogenic action [146].…”

Adipose Tissue - An Update

“…Obesity also represents an imbalance between the primary site of storing energy (the white fat) and the site that is specialized in energy expenditure (the brown fat) [14]. White adipocytes store fat in the form of triacylglycerols as a single fat lipid droplet that gets readily hydrolyzed by lipases when energy is needed.…”

LncRNAs in Stem Cells

“…The induction was correlated with the stimulation of the thermogenic gene program and in consistency with the expression of key thermogenic markers such as Ucp1 in adipose tissues. Blnc1 is primarily localized in the nucleus and forms a ribonucleoprotein complex with EBF2, which is a member of the EBF family of transcription factors that has been implicated in the control of adipogenesis [ 37 ]. Blnc1 itself is also a target of EBF2, thereby forming a feed-forward regulatory loop to regulate adipocyte gene expression.…”