Regulation of NR4A by nutritional status, gender, postnatal development and hormonal deficiency.

The NR4A is a subfamily of the orphan nuclear receptors (NR) superfamily constituted by three well characterized members: Nur77 (NR4A1), Nurr1 (NR4A2) and Nor 1 (NR4A3). They are implicated in numerous biological processes as DNA repair, arteriosclerosis, cell apoptosis, carcinogenesis and metabolism. Several studies have demonstrated the role of this subfamily on glucose metabolism, insulin sensitivity and energy balance. These studies have focused mainly in liver and skeletal muscle. However, its potential role in white adipose tissue (WAT), one of the most important tissues involved in the regulation of energy homeostasis, is not well-studied. The aim of this work was to elucidate the regulation of NR4A in WAT under different physiological and pathophysiological settings involved in energy balance such as fasting, postnatal development, gender, hormonal deficiency and pregnancy. We compared NR4A mRNA expression of Nur77, Nurr1 and Nor 1 and found a clear regulation by nutritional status, since the expression of the 3 isoforms is increased after fasting in a leptin-independent manner and sex steroid hormones also modulate NR4A expression in males and females. Our findings indicate that NR4A are regulated by different physiological and pathophysiological settings known to be associated with marked alterations in glucose metabolism and energy status.