Regulation of ABCA1 and ABCG1 transporter gene expression in the intraabdominal adipose tissue

Abstract

Tissue specific expression of genes encoding the cholesterol transporters ABCA1 and ABCG1 as well as genes encoding the most important transcriptional regulators of adipogenesis (LXRα, LXRβ, PPARγ and RORα) has been investigated in intraabdominal adipose tissue (IAT) samples from obese patients and patients without overweight. A direct correlation between the content of ABCA1 and ABCG1 proteins and the RORα protein level (r = 0.480, p < 0.05; r = 0.435, p < 0.05, respectively) suggests involvement of the transcription factor RORα in the regulation of ABCA1 and ABCG1 protein levels in IAT. ABCA1 and ABCG1 gene expression positively correlated with such obesity indicators as body mass index (BMI) (r = 0.522, p = 0.004; r = 0.594, p = 0.001, respectively) and waist circumference (r = 0.403, p = 0.033; r = 0.474, p = 0.013, respectively). The development of obesity is also associated with decreased IAT levels of RORα and LXRβ mRNA (p = 0.016 and p = 0.002, respectively). This suggest that the nuclear factor RORα can play a significant role in the regulation of cholesterol metabolism and control IAT expression of ABCA1 and ABCG1 genes, while the level of IAT LXRβ gene expression may be an important factor associated with the development of obesity.