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

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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 BATB and WATB adipocytes, respectively, were compared.

Results:

The BATB and WATB adipocytes were morphologically different. The expressions of UCP1, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), leptin and resistin mRNAs were low in WATB adipocytes as compared with those in BATB adipocytes. The expressions of UCP1 and PGC-1α proteins were, however, much higher in WATB adipocytes, amounting 51% and 36% of those in BATB adipocytes. The patterns of expression of UCP1, PGC-1α and leptin in the BATB and in WATB adipocytes were different with a higher relative expression of PGC-1α in the latter. Rosiglitazone increased UCP1 mRNA expression 4.5-fold in the BATB and significantly more, 7.9-fold, in the WATB adipocytes. Retinoic acid and triiodothyronine increased UCP1 mRNA expression in the BATB adipocytes 1.6- and 2-fold, respectively but, surprisingly, slightly decreased UCP1 mRNA expression in the WATB 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.

Conclusions:

International Journal of Obesity (2009) 33, 680-686; doi:10.1038/ijo.2009.46; published online 10 March 2009

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