Sterol regulatory element binding protein 1c (SREBP-1c) expression in human obesity

Objective: Investigation of the expression of sterol regulatory element bin ding protein-1c (SREBP-1c) in different adipose tissue depots in morbidly o bese subjects before and after 1 year of weight loss induced by gastric ban ding operation. Research Methods and Procedures: SREBP-1c expression was studied in 20 mass ively obese subjects (6 men and 14 women; age: 41 +/- 9 years; weight: 148 +/- 34 kg; percentage of body fat: 42 +/- 4; mean +/- SD) using reverse tra nscription competitive polymerase chain reaction. Adipose tissue biopsies w ere taken from omental, subcutaneous abdominal, and femoral depots before w eight loss, and from subcutaneous depots after weight loss. Subcutaneous sa mples were taken also from 6 normal weight subjects. Results: The level of SREBP-1c mRNA was significantly lower in omental (1.8 +/- 0.2 amol/mug of total RNA) than in subcutaneous abdominal (3.7 +/- 0.4 amol/mug of total RNA) or femoral (3.9 +/- 0.4 amol/mug of total RNA; p < 0.001, mean SEM) depots. The values in subcutaneous depots were about twice as high in normal weight (7.4 +/- 2.5 for abdominal and 6.5 +/- 1.5 for fe moral, p < 0.01) as in obese subjects. After weight loss, the mRNA levels o f SREBP-1c increased in obese subjects, both in subcutaneous abdominal (5.3 +/- 0.7, p < 0.01) and in femoral (4.8 +/- 0.8, p < 0.05) tissue. Discussion: SREBP-1c mRNA expression was lower in omental adipose tissue th an in subcutaneous depots in obese subjects before weight loss. Furthermore , the expression of SREBP-Ic in obese subjects was clearly lower than in no rmal weight subjects, but mRNA levels increased along with weight reduction . Weight reduction was associated with increased mRNA levels of SREBP-1c in obese subjects. The reduced expression of SREBP-1c in obesity could be asc ribed to lowered action or concentration of insulin, changeable along, with weight reduction. However, changes in SREBP-1c expression after weight red uction could also be ascribed to the changes in calorie intake or nutrition al habits after castric banding operation.