Weight loss reduces expression of SREBP1c/ADD1 and PPAR gamma 2 in adiposetissue of obese women

Weight loss in obese patients, even if moderate, is clearly beneficial for health and implies a reduction in either adipocyte number or volume. This c an be regulated by the key adipose transcription factors, sterol-regulatory -element binding protein-1c/adipocyte differentiation and determination fac tor-1 (SREBP1c/ADD1), peroxisome proliferator-activated receptor-gamma2 (PP AR gamma2) and CCAAT-enhancer binding protein-alpha (C/EBP alpha), which re gulate the adipocyte metabolism and differentiation process. The present st udy was undertaken to obtain insights into the expression of these transcri ption factors during moderate weight loss in humans. In addition, the adipo se depot-related differences and the relation to adipose lipoprotein lipase (LPL) expression and plasma lipids were studied. Using quantitative revers e transcription polymerase chain reaction (RT-PCR), the total amount of eac h adipose transcription factor messenger ribonucleic acid (mRNA) was determ ined in the subcutaneous or omental adipose tissue after a controlled, 2-mo nth, bodyweight-reduction trial in 11 obese middle-aged women and 17 compar able obese controls. Weight loss (6% of body weight) was associated with re duced serum insulin and plasma triacylglycerols. Adipose tissue PPAR gamma2 and SREBP1c/ADD1 mRNA were lower in the weight-loss group than in controls (by 30% and 28%, respectively), whereas the C/EBP alpha mRNA level did not change. Moreover, PPAR gamma2 mRNA was lower only in the subcutaneous adip ose depot and was related to both adipose tissue lipoprotein lipase (LPL) m RNA and improvement in plasma triacylglycerols in the weight-loss group. Ou r results suggest a functional role for SREBP1c/ADD1 and PPAR gamma2 in the control of energy metabolism in human adipose tissue.