Promoter analysis of the mouse sterol regulatory element-binding protein-1c gene.
Recent data suggest that sterol regulatory-binding protein (SREBP)-1c plays a key role in the transcriptional regulation of different lipogenic genes mediating lipid synthesis as a key regulator of fuel metabolism. SREBP-1c regulates its downstream genes by changing its own mRNA level, which led us to sequence and analyze the promoter region of the mouse SREBP-1c gene. A cluster of putative binding sites of several transcription factors composed of an NF-Y site, an E-box, a sterol-regulatory element 3, and an Sp1 site were located at -90 base pairs of the SREBP-1c promoter. Luciferase reporter gene assays indicated that this SRE complex is essential to the basal promoter activity and confers responsiveness to activation by nuclear SREBPs. Deletion and mutation analyses suggest that the NF-Y site and SRE3 in the SRE complex are responsible for SREBP activation, although the other sites were also involved in the basal activity. Gel mobility shift assays demonstrate that SREBP-1 binds to the SRE3. Taken together, these findings implicate a positive loop production of SREBP-1c through the SRE complex, possibly leading to the overshoot in induction of SREBP-1c and its downstream genes seen in the livers of refed mice. Furthermore, reporter assays using larger upstream fragments indicated another region that was inducible by addition of sterols. The presence of the SRE complex and a sterol-inducible region in the same promoter suggests a novel regulatory link between cholesterol and fatty acid synthesis.
Department of Metabolic Diseases, Faculty of Medicine and the Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8655, Japan.
M
M
Amemiya-Kudo
H
H
Shimano
T
T
Yoshikawa
N
N
Yahagi
A H
AH
Hasty
H
H
Okazaki
Y
Y
Tamura
F
F
Shionoiri
Y
Y
Iizuka
K
K
Ohashi
J
J
Osuga
K
K
Harada
T
T
Gotoda
R
R
Sato
S
S
Kimura
S
S
Ishibashi
N
N
Yamada
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002784:Cholesterol / Q000096:biosynthesis; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D005227:Fatty Acids / Q000096:biosynthesis; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D006801:Humans; D008099:Liver / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection; D015854:Up-Regulation
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D005227:Fatty Acids; D020033:Protein Isoforms; D012333:RNA, Messenger; D011994:Recombinant Proteins; C497387:SREBF1 protein, human; C497388:Srebf1 protein, mouse; D051780:Sterol Regulatory Element Binding Protein 1; D014157:Transcription Factors; D002784:Cholesterol; D008156:Luciferases