PPAR α does not suppress muscle - associated gene expression in brown adipocytes

Brown adipocytes and myocytes develop from a common adipomyocyte precursor. PPARα is a nuclear receptor important for lipid and glucose metabolism. It has been suggested that in brown adipose tissue, PPARα represses the expression of muscle-associated genes, in this way potentially acting to determinate cell fate in brown adipocytes. To further understand the possible role of PPARα in these processes, we measured muscle-associated gene expression in brown adipose tissue and brown adipocytes from PPARα-ablated mice, including structural genes (Mylpf, Tpm2, Myl3 and MyHC), regulatory genes (myogenin, Myf5 and MyoD) and a myomir ((miR-206), as well as genes that are part of the brown adipocyte signature (Tbx15, Meox2, Zic1 and Lhx8). However, we report here that in our hands the expression of these genes was not influenced by the presence or absence of PPARα, nor by the PPARα activator Wy-14,643. Thus, it would not seem that PPARα plays a significant role in the regulation of the bifurcation of the adipomyocyte precursor into a brown adipocyte or myocyte phenotype; particulary, it would not seem that PPARα represses muscle-associated genes.