Increased lipogenic potential of rat adipose tissue after repeated dieting--the role of SREBP-1 transcription factor.
Repeated dieting is one of the methods used for weight reduction; however, its effectiveness is questionable. We developed an experimental, rat model of repeated dieting, which mimics the dietary approach used in the treatment of obesity in humans. In this experimental model, despite the lower caloric intake, decreased body mass and reduced fat stores, the lipogenic potential of adipose tissue increased. We observed a substantial increase in fatty acid synthase (a key lipogenic enzyme) gene expression in rat adipose tissue accompanied by a 9-fold increase in the serum insulin level. Fatty acid synthase gene expression is controlled at the transcriptional level by SREBP-1. In this study, a remarkable increase (24-fold) in SREBP-1 protein amount, parallel to that in fatty acid synthase mRNA level, protein concentration and enzyme activity was observed after multiple cycles of fasting-refeeding. Although it is possible that the interactions between transcription factors are more complex, we propose that the pivotal role in the increase of the lipogenic potential of adipose tissue after repeated dieting may be played by SREBP-1.
Kochan
Zdzislaw
Z
Department of Biochemistry, Medical University of Gdansk, Debinki 1, 80-211 Gdansk, Poland. kochanz@amg.gda.pl
D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology*; D005215:Fasting / Q000502:physiology; D064429:Fatty Acid Synthases / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D008066:Lipolysis / Q000502:physiology; D008297:Male; D009765:Obesity / Q000178:diet therapy* / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors / Q000378:metabolism*
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D007328:Insulin; C497389:Srebf1 protein, rat; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D064429:Fatty Acid Synthases