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Spatial distribution and function of sterol regulatory element-binding protein 1a and 2 homo- and heterodimers by in vivo two-photon imaging and spectroscopy fluorescence resonance energy transfer
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Zoumi A Datta S Liaw LH Wu CJ Manthripragada G Osborne TF Lamorte VJ 《Molecular and cellular biology》2005,25(8):2946-2956
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Inoue J Kumagai H Terada T Maeda M Shimizu M Sato R 《Biochemical and biophysical research communications》2001,283(5):1157-1161
A member of sterol regulatory element-binding protein (SREBP) family, SREBP-1, is a key regulator of adipocyte differentiation. Expression of the SREBP-1 gene is induced during adipocyte differentiation, but proteolytic activation of the synthesized precursor form of SREBP-1 has not been well analyzed. The proteolytic processing of SREBPs is severely suppressed in sterol loaded culture cells. Here we report that a splicing isoform, SREBP-1a, is predominantly expressed in 3T3-L1 preadipocytes and adipocytes, and that the nuclear active form of SREBP-1 protein increases in adipocyte differentiation. We further show that the amount of nuclear SREBP-2 protein also increases despite no increase in SREBP-2 mRNA, suggesting that proteolytic cleavage of SREBPs is induced in lipid loaded adipocytes. Northern blot analyses reveal that mRNA levels for SREBP cleavage-activating protein (SCAP), Site-1 protease (S1P), and Site-2 protease (S2P), which participate in the proteolytic processing of SREBPs, are relatively unaffected in adipogenesis. These results demonstrate that SREBP-2 appears to promote adipocyte differentiation as well as SREBP-1 and that the proteolytic activation of SREBPs may be induced by an as-yet unidentified mechanism in lipid loaded adipocytes. 相似文献
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Horton JD Shimomura I Ikemoto S Bashmakov Y Hammer RE 《The Journal of biological chemistry》2003,278(38):36652-36660
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Regulation of Peroxisome Proliferator-Activated Receptor γ Expression by Adipocyte Differentiation and Determination Factor 1/Sterol Regulatory Element Binding Protein 1: Implications for Adipocyte Differentiation and Metabolism 总被引:1,自引:0,他引:1
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Lluis Fajas Kristina Schoonjans Laurent Gelman Jae B. Kim Jamila Najib Genevieve Martin Jean-Charles Fruchart Michael Briggs Bruce M. Spiegelman Johan Auwerx 《Molecular and cellular biology》1999,19(8):5495-5503
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Arito M Horiba T Hachimura S Inoue J Sato R 《The Journal of biological chemistry》2008,283(22):15224-15231
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Unsaturated fatty acids down-regulate srebp isoforms 1a and 1c by two mechanisms in HEK-293 cells 总被引:13,自引:0,他引:13
Hannah VC Ou J Luong A Goldstein JL Brown MS 《The Journal of biological chemistry》2001,276(6):4365-4372
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Sterol regulatory element-binding proteins induce an entire pathway of cholesterol synthesis 总被引:2,自引:0,他引:2
Sakakura Y Shimano H Sone H Takahashi A Inoue N Toyoshima H Suzuki S Yamada N Inoue K 《Biochemical and biophysical research communications》2001,286(1):176-183
To evaluate the effects of sterol regulatory element-binding proteins (SREBPs) on the expression of the individual enzymes in the cholesterol synthetic pathway, we examined expression of these genes in the livers from wild-type and transgenic mice overexpressing nuclear SREBP-1a or -2. As estimated by a Northern blot analysis, overexpression of nuclear SREBP-1a or -2 caused marked increases in mRNA levels of the whole battery of cholesterogenic genes. This SREBP activation covers not only rate-limiting enzymes such as HMG CoA synthase and reductase that have been well established as SREBP targets, but also all the enzyme genes in the cholesterol synthetic pathway tested here. The activated genes include mevalonate kinase, mevalonate pyrophosphate decarboxylase, isopentenyl phosphate isomerase, geranylgeranyl pyrophosphate synthase, farnesyl pyrophosphate synthase, squalene synthase, squalene epoxidase, lanosterol synthase, lanosterol demethylase, and 7-dehydro-cholesterol reductase. These results demonstrate that SREBPs activate every step of cholesterol synthetic pathway, contributing to an efficient cholesterol synthesis. 相似文献
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Transcriptional activities of nuclear SREBP-1a, -1c,and -2 to different target promoters of lipogenic and cholesterogenic genes 总被引:5,自引:0,他引:5
Amemiya-Kudo M Shimano H Hasty AH Yahagi N Yoshikawa T Matsuzaka T Okazaki H Tamura Y Iizuka Y Ohashi K Osuga J Harada K Gotoda T Sato R Kimura S Ishibashi S Yamada N 《Journal of lipid research》2002,43(8):1220-1235
Recent studies on the in vivo roles of the sterol regulatory element binding protein (SREBP) family indicate that SREBP-2 is more specific to cholesterogenic gene expression whereas SREBP-1 targets lipogenic genes. To define the molecular mechanism involved in this differential regulation, luciferase-reporter gene assays were performed in HepG2 cells to compare the transactivities of nuclear SREBP-1a, -1c, and -2 on a battery of SREBP-target promoters containing sterol regulatory element (SRE), SRE-like, or E-box sequences. The results show first that cholesterogenic genes containing classic SREs in their promoters are strongly and efficiently activated by both SREBP-1a and SREBP-2, but not by SREBP-1c. Second, an E-box containing reporter gene is much less efficiently activated by SREBP-1a and -1c, and SREBP-2 was inactive in spite of its ability to bind to the E-box. Third, promoters of lipogenic enzymes containing variations of SRE (SRE-like sequences) are strongly activated by SREBP-1a, and only modestly and equally by both SREBP-1c and -2. Finally, substitution of the unique tyrosine residue within the basic helix-loop-helix (bHLH) portion of nuclear SREBPs with arginine, the conserved residue found in all other bHLH proteins, abolishes the transactivity of all SREBPs for SRE, and conversely results in markedly increased activity of SREBP-1 but not activity of SREBP-2 for E-boxes. These data demonstrate the different specificity and affinity of nuclear SREBP-1 and -2 for different target DNAs, explaining a part of the mechanism behind the differential in vivo regulation of cholesterogenic and lipogenic enzymes by SREBP-1 and -2, respectively. 相似文献
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