The roles of sterol regulatory element-binding proteins in the transactivation of the rat ATP citrate-lyase promoter.
ATP citrate-lyase (ACL) is a key enzyme supplying acetyl-CoA for fatty acid and cholesterol synthesis. Its expression is drastically up-regulated when an animal is fed a low fat, high carbohydrate diet after prolonged fasting. In this report, we describe the role of sterol regulatory element-binding proteins (SREBPs) in the transactivation of the rat ACL promoter. ACL promoter activity was markedly stimulated by the overexpression of SREBP-1a and, to a lesser extent, by SREBP-2 in Alexander human hepatoma cells. The promoter elements responsive to SREBPs were located within the 55-base pair sequences from -114 to -60. The gel mobility shift assay revealed four SREBP-1a binding sites in this region. Of these four elements, the -102/-94 region, immediately upstream of the inverted Y-box, and the -70/-61 region, just adjacent to Sp1 binding site, played critical roles in SREBPs-mediated stimulation. The mutation in the inverted Y-box and the coexpression of dominant negative nuclear factor-Y (NF-Y) significantly attenuated the transactivation by SREBP-1a, suggesting that NF-Y binding is a prerequisite for SREBPs to activate the ACL promoter. However, the multiple Sp1 binding sites did not affect the transactivation of the ACL promoter by SREBPs. The binding affinity of SREBP-1a to SREs of the ACL promoter also was much higher than that of SREBP-2. The transactivation potencies of the chimeric SREBPs, of which the activation domains (70 amino acids of the amino terminus) were derived from the different species of their carboxyl-terminal region, were similar to those of SREBPs corresponding to their carboxyl termini. Therefore, it is suggested that the carboxyl-terminal portions of SREBPs containing DNA binding domains are important in determining their transactivation potencies to a certain promoter.
Moon
Y A
YA
Department of Biochemistry and Molecular Biology, Institute of Genetic Science, Yonsei University College of Medicine, 134, Shinchon-dong, Seodaemun-gu, Seoul 120-752, South Korea.
Lee
J J
JJ
Park
S W
SW
Ahn
Y H
YH
Kim
K S
KS
D001275:ATP Citrate (pro-S)-Lyase / Q000235:genetics*; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D023081:CCAAT-Binding Factor / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism*; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I; D006801:Humans; D008099:Liver / Q000201:enzymology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D051780:Sterol Regulatory Element Binding Protein 1; D051782:Sterol Regulatory Element Binding Protein 2; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
D023081:CCAAT-Binding Factor; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; C497387:SREBF1 protein, human; C497390:SREBF2 protein, human; C497389:Srebf1 protein, rat; D051780:Sterol Regulatory Element Binding Protein 1; D051782:Sterol Regulatory Element Binding Protein 2; D014157:Transcription Factors; D001275:ATP Citrate (pro-S)-Lyase; D003850:Deoxyribonuclease I