Brn-3b and PPARy Nuclear Receptor Expression in Adipose Tissue of Human Subjects

Abstract

Obesity rates have reached alarming heights globally, having more than doubled since the 1980's. Over 60% of diabetic patients are obese, and the increasing severity of the disease is associated with Type 2 Diabetes Mellitus (T2DM) incidence, which is reversible by weight loss could trigger the development of new medication, procedures and perhaps devices. Peroxisome proliferator-activated receptor gamma (PPARy) is a nuclear receptor expressed in adipose tissue and regulates the expression of genes involved in both adipocyte differenctiation and lipid metabolism. Another novel transcription factor, Brn-3b, known to be involved in neuronal development, has recently been shown to be expressed in murine adipose tissue and also in peripheral blood cells (PBCs) obtained from morbidly obese patients. Furthermore, the expression of Brn-3b was significantly reduced in PBCs of diabetic patients. The aim of this study was to investigate the expression of PPARy and Brn-3b in cells of the adipose tissue of obese patients undergoing weight-reducing sleeve gastrostomy. Anthropometric and biochemical data were collected for all patients. Samples from two abdominal adipose tissue depots (subcutaneous and omental) were also obtained from each patient. RNA was extracted and qPCR for PPARy and Brn-3b was performed. Our results showed that PPARy is highly expressed in the adipocytes of omental adipose tissue when compared to the adipocytes of the subcutaneous adipose tissue, while Brn-3b was not detectable in adipocytes, but exclusive expressed in the stromal vascular fraction, especially of the subcutaneous adipose tissue. The expression of Brn-3b increased the rising levels of systemic insulin and was also elevated in the SVF of patients with metabolic disease compared with those without. In conclusion our study indicated that there was a reciporacal relationship between the expression of PPARy and Brn-3b that needs further investigation, and raises questions concerning the implication of Brn-3b in the pathology of obesity and T2DM.