Is There a Brite Future for Brown Adipose Tissue?Thursday, June 13, 2013
One of the Holy Grails of weight loss is to find something that will ‘boost’ their metabolism and help them burn off extra calories.
This topic has gained significant momentum with the discovery of brown adipose tissue (BAT), a tissue exquisitely designed to burn calories. It is estimated that a few ounces of BAT can burn hundreds of excess calories per day – equivalent to the calories in several cheese burgers – all while sitting peacefully in your armchair or at your desk.
An article by Alessandro Peschechera (Bari, Italy) and Juergen Eckel (Duesseldorf, Germnay), published in the Archives of Physiology and Biochemistry, takes an in depth look at the molecular biology of BAT and potential therapeutic approaches to harnessing this tissue for weight management.
It appears that brown adipocytes are derived via a distinctive pathway from skeletal muscle precursor cells, different from that of white adipocytes. However, there is now convincing evidence that white adipocytes can aquire some of the properties of brown adipocytes through transdifferentiation. Such transdifferentiated adipocytes are commonly referred to as “brite” (or brown-in-white) adipocytes.
Brite adipocyte precursor cells are typically found in white adipose tissue depots and have the ability to switch from an energy storage to an energy dissipation mode.
On the other hand, there is also some research to suggest that in states of energy abundance, brown adipocytes can switch to a predominantly energy storage mode, thereby losing their ability to burn excess calories.
Obviously, there is now considerable interest in the concept of “browning” of adipose tissue as a means of increasing energy dissipation.
This is why a better understanding of master switches of BAT formation like PRDM16, PGC1a, FoxC2, Tbx15, BMP7, FGF21, and and some mitochondrial RNAs are attracting considerable interest.
It is also worth noting that GLP-1 (via a central effect) and ANP may have direct effects on adipose tissue browning.
From a more practical perspective it is worth noting that cold exposure and exercise have both been shown to increase BAT, an effect that may be largely mediated through the sympathetic (adrenergic) nervous system (or in the case of exercise possibly via myokines like irisin).
Currently, little of this knowledge translates into effective or practical clinical interventions for obesity prevention or treatment but clinicians should stay tuned to the work happening in this field, which may well lead to novel interventions for obesity.
Peschechera A, & Eckel J (2013). “Browning” of adipose tissue – regulation and therapeutic perspectives. Archives of physiology and biochemistry PMID: 23721302