Oestrogen receptor α gene expression levels are reduced in obese compared to normal weight females

Objective: To determine whether oestrogen receptor (ER)α messenger RNA (mRNA) levels or single nucleotide polymorphisms (SNPs) are associated with obesity in Swedish women. Design: ERα mRNA expression levels were measured by real-time qPCR in subcutaneous adipose tissue from non-obese (N=16, BMI <30) and obese (N=17, BMI ≥30) women. In addition, ERα mRNA expression levels were determined in isolated adipocytes. ERα promoter usage was characterized by 5′ RACE and by real-time qPCR in subcutaneous adipose tissue from the same non-obese and obese women. Two ERα SNPs were scored in 509 non-obese and 489 obese females. Results: ERα mRNA expression levels were lower in obese compared to non-obese women in both subcutaneous adipose tissue and in adipocytes. We show that two ERα promoters are differentially utilized in obese and non-obese individuals. We did not find any significant association between obesity and the ERα SNPs or haplotypes assayed. Conclusion: The reduced ERα mRNA levels observed in adipose tissue from obese compared to non-obese women support a role for oestrogen signaling via ERα, in control of body weight. Mechanistic studies of the role of ERα in adipocytes and how its expression is regulated in relation to fat mass should be performed. The latter studies should focus on the two promoters that are used differently in obese and non-obese individuals.