Differentiation and characterization in primary culture of white adipose tissue brown adipocyte-like cells

Abstract

Background: Rodent brown adipose tissue (BAT) is considered the main effector of adaptative thermogenesis as it contains a unique mitochondrial uncoupling protein, termed as uncoupling protein-1 (UCP1). The emergence of ectopic brown adipocytes in the white adipose tissue (WAT), called recruitment, might play an important role in the prevention of obesity. The recruitment phenomenon has until now been investigated mostly in vivo. Objectives: This study is an attempt to mimic in vitro the recruitment phenomenon. It consisted in culturing the stroma vascular fractions of mouse BAT and WAT in a brown adipocyte differentiation medium. The multilocular cells obtained, referred to as BAT B and WAT B adipocytes, respectively, were compared. Results: The BAT B and WAT B adipocytes were morphologically different. The expressions of UCP1, peroxisome proliferatoractivated receptor-g coactivator-1a (PGC-1a), leptin and resistin mRNAs were low in WAT B adipocytes as compared with those in BAT B adipocytes. The expressions of UCP1 and PGC-1a proteins were, however, much higher in WAT B adipocytes, amounting 51% and 36% of those in BAT B adipocytes. The patterns of expression of UCP1, PGC-1a and leptin in the BAT B and in WAT B adipocytes were different with a higher relative expression of PGC-1a in the latter. Rosiglitazone increased UCP1 mRNA expression 4.5-fold in the BAT B and significantly more, 7.9-fold, in the WAT B adipocytes. Retinoic acid and triiodothyronine increased UCP1 mRNA expression in the BAT B adipocytes 1.6-and 2-fold, respectively but, surprisingly, slightly decreased UCP1 mRNA expression in the WAT B adipocytes. Conclusions: The study suggests that the nature and possibly the origin of WAT brown adipocytes is different from that of BAT brown adipocytes. It proposes an in vitro approach that could prove very useful to better characterize the WAT brown adipocyte-like cells.

Apelin Enhances Brown Adipogenesis and Browning of White Adipocytes

“…Because both apelin and APJ are abundantly expressed in white adipocytes (24, 59), we sought to investigate apelin's effects on browning of white adipocytes. Consistent with previous studies (13,60), it was found that UCP1 expression in human white adipocytes is much lower than in brown adipocytes (Fig. 5).…”

Characteristics of Beige Adipocytes Induced from White Adipocytes by <i>Kikyo</i> Extract

“…These results suggested that the changes from white adipocytes to beige ones might not be a result of differentiation but simply a change to a high-performance type of cell. Several studies had suggested that beige adipocytes were a kind of white adipocyte [35] [36], findings which supported our own. However, the transgenic brown adipocytes expressing the PRDM16 gene at a high level [16] showed stable characteristics, and natural brown adipocytes taken from the body might also be stable.…”

Effect of vitamin A deficiency on the immune response in obesity

“…In vitro, RA increased 1 . 6 times UCP-1 mRNA expression in the BAT and slightly decreased its expression in WAT adipocytes (68) . In addition to the UCP-1 gene transcription, RA has been found in vitro to decrease preadipocyte survival time and to inhibit or promote adipose cell differentiation depending on the dose, probably regulated by RA intracellular lipid-binding protein-II (59,(69)(70)(71)(72) .…”