Abstract
Glutamine synthetase (GS) expression increases dramatically during adipocyte differentiation of confluent 3T3-L1 cells. To identify differentiation-responsive cis-acting elements in the GS gene, several GSfusion genes were prepared and analyzed in stably transfected 3T3-L1 cells under conditions that trigger adipocyte differentiation. We find that the GS proximal 5'-flanking sequence lacks the regulatory elements required for differentiation-responsive expression. In contrast, a 2 kb intron 1 restriction fragment fused upstream of a heterologous promoter does drive reporter gene expression during hormone-triggered differentiation. The enhancer activity was localized to a 310 bp sequence near the middle of intron 1. Expression of fusion genes that include this 310 bp sequence does not temporally coincide with native gene expression. However, a composite gene that includes a far upstream GS sequence and the 2 kb intron 1 sequence yields a qualitatively different pattern of expression that closely resembles that of the native GS gene. The far upstream sequence alone exhibits no enhancer activity. Electrophoretic mobility shift analyses indicate that a 32 bp sequence within the 310 bp functional enhancer specifically binds differentiation-associated nuclear proteins. Although a C/EBP consensus sequence occurs in the 32 bp fragment, supershift analyses exclude C/EBP isoforms as the binding factor. In contrast, mutational analysis of the putative enhancer suggests that an HNF-3 isoform is involved. Thus our data indicate that elements in the distal 5'-flanking sequence and the first intron function cooperatively to regulate GS transcription and that HNF-3 may participate in that regulation.
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- Bennett A. L., Paulson K. E., Miller R. E., Darnell J. E., Jr Acquisition of antigens characteristic of adult pericentral hepatocytes by differentiating fetal hepatoblasts in vitro. J Cell Biol. 1987 Sep;105(3):1073–1085. doi: 10.1083/jcb.105.3.1073. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Bhandari B., Burns D. M., Hoffman R. C., Miller R. E. Glutamine synthetase mRNA in cultured 3T3-L1 adipocytes. Complexity, content and hormonal regulation. Mol Cell Endocrinol. 1986 Sep;47(1-2):49–57. doi: 10.1016/0303-7207(86)90015-8. [DOI] [PubMed] [Google Scholar]
- Bhandari B., Miller R. E. Glutamine synthetase gene transcription in cultured 3T3-L1 adipocytes: regulation by dexamethasone, insulin and dibutyryl cyclic AMP. Mol Cell Endocrinol. 1987 May;51(1-2):7–11. doi: 10.1016/0303-7207(87)90112-2. [DOI] [PubMed] [Google Scholar]
- Bhandari B., Roesler W. J., DeLisio K. D., Klemm D. J., Ross N. S., Miller R. E. A functional promoter flanks an intronless glutamine synthetase gene. J Biol Chem. 1991 Apr 25;266(12):7784–7792. [PubMed] [Google Scholar]
- Brinster R. L., Allen J. M., Behringer R. R., Gelinas R. E., Palmiter R. D. Introns increase transcriptional efficiency in transgenic mice. Proc Natl Acad Sci U S A. 1988 Feb;85(3):836–840. doi: 10.1073/pnas.85.3.836. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chaney W. G., Howard D. R., Pollard J. W., Sallustio S., Stanley P. High-frequency transfection of CHO cells using polybrene. Somat Cell Mol Genet. 1986 May;12(3):237–244. doi: 10.1007/BF01570782. [DOI] [PubMed] [Google Scholar]
- Chodosh L. A., Carthew R. W., Sharp P. A. A single polypeptide possesses the binding and transcription activities of the adenovirus major late transcription factor. Mol Cell Biol. 1986 Dec;6(12):4723–4733. doi: 10.1128/mcb.6.12.4723. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Clevidence D. E., Overdier D. G., Tao W., Qian X., Pani L., Lai E., Costa R. H. Identification of nine tissue-specific transcription factors of the hepatocyte nuclear factor 3/forkhead DNA-binding-domain family. Proc Natl Acad Sci U S A. 1993 May 1;90(9):3948–3952. doi: 10.1073/pnas.90.9.3948. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fahrner J., Labruyere W. T., Gaunitz C., Moorman A. F., Gebhardt R., Lamers W. H. Identification and functional characterization of regulatory elements of the glutamine synthetase gene from rat liver. Eur J Biochem. 1993 May 1;213(3):1067–1073. doi: 10.1111/j.1432-1033.1993.tb17854.x. [DOI] [PubMed] [Google Scholar]
- Gaunitz F., Gaunitz C., Papke M., Gebhardt R. Cis-regulatory sequences from the first intron of the rat glutamine synthetase gene are involved in hepatocyte specific expression of the enzyme. Biol Chem. 1997 Jan;378(1):11–18. doi: 10.1515/bchm.1997.378.1.11. [DOI] [PubMed] [Google Scholar]
- Kuo C. F., Darnell J. E., Jr Mouse glutamine synthetase is encoded by a single gene that can be expressed in a localized fashion. J Mol Biol. 1989 Jul 5;208(1):45–56. doi: 10.1016/0022-2836(89)90086-7. [DOI] [PubMed] [Google Scholar]
- Kushner P. J., Baxter J. D., Duncan K. G., Lopez G. N., Schaufele F., Uht R. M., Webb P., West B. L. Eukaryotic regulatory elements lurking in plasmid DNA: the activator protein-1 site in pUC. Mol Endocrinol. 1994 Apr;8(4):405–407. doi: 10.1210/mend.8.4.8052261. [DOI] [PubMed] [Google Scholar]
- Laborda J. 36B4 cDNA used as an estradiol-independent mRNA control is the cDNA for human acidic ribosomal phosphoprotein PO. Nucleic Acids Res. 1991 Jul 25;19(14):3998–3998. doi: 10.1093/nar/19.14.3998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lie-Venema H., Labruyère W. T., van Roon M. A., de Boer P. A., Moorman A. F., Berns A. J., Lamers W. H. The spatio-temporal control of the expression of glutamine synthetase in the liver is mediated by its 5'-enhancer. J Biol Chem. 1995 Nov 24;270(47):28251–28256. doi: 10.1074/jbc.270.47.28251. [DOI] [PubMed] [Google Scholar]
- Luckow B., Schütz G. CAT constructions with multiple unique restriction sites for the functional analysis of eukaryotic promoters and regulatory elements. Nucleic Acids Res. 1987 Jul 10;15(13):5490–5490. doi: 10.1093/nar/15.13.5490. [DOI] [PMC free article] [PubMed] [Google Scholar]
- MacDougald O. A., Lane M. D. Transcriptional regulation of gene expression during adipocyte differentiation. Annu Rev Biochem. 1995;64:345–373. doi: 10.1146/annurev.bi.64.070195.002021. [DOI] [PubMed] [Google Scholar]
- Mill J. F., Mearow K. M., Purohit H. J., Haleem-Smith H., King R., Freese E. Cloning and functional characterization of the rat glutamine synthetase gene. Brain Res Mol Brain Res. 1991 Feb;9(3):197–207. doi: 10.1016/0169-328x(91)90003-g. [DOI] [PubMed] [Google Scholar]
- Miller R. E., Carrino D. A. An association between glutamine synthetase activity and adipocyte differentiation in cultured 3T3-L1 cells. Arch Biochem Biophys. 1981 Jul;209(2):486–503. doi: 10.1016/0003-9861(81)90307-6. [DOI] [PubMed] [Google Scholar]
- Miller R. E., Carrino D. A. Dibutyryl cyclic AMP decreases glutamine synthetase in cultured 3T3-L1 adipocytes. J Biol Chem. 1980 Jun 10;255(11):5490–5500. [PubMed] [Google Scholar]
- Miller R. E., Hackenberg R., Gershman H. Regulation of glutamine synthetase in cultured 3T3-L1 cells by insulin, hydrocortisone, and dibutyryl cyclic AMP. Proc Natl Acad Sci U S A. 1978 Mar;75(3):1418–1422. doi: 10.1073/pnas.75.3.1418. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Miller R. E., Pope S. R., DeWille J. W., Burns D. M. Insulin decreases and hydrocortisone increases the synthesis of glutamine synthetase in cultured 3T3-L1 adipocytes. J Biol Chem. 1983 May 10;258(9):5405–5413. [PubMed] [Google Scholar]
- Reid L. H., Gregg R. G., Smithies O., Koller B. H. Regulatory elements in the introns of the human HPRT gene are necessary for its expression in embryonic stem cells. Proc Natl Acad Sci U S A. 1990 Jun;87(11):4299–4303. doi: 10.1073/pnas.87.11.4299. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Seed B., Sheen J. Y. A simple phase-extraction assay for chloramphenicol acyltransferase activity. Gene. 1988 Jul 30;67(2):271–277. doi: 10.1016/0378-1119(88)90403-9. [DOI] [PubMed] [Google Scholar]
- Tontonoz P., Kim J. B., Graves R. A., Spiegelman B. M. ADD1: a novel helix-loop-helix transcription factor associated with adipocyte determination and differentiation. Mol Cell Biol. 1993 Aug;13(8):4753–4759. doi: 10.1128/mcb.13.8.4753. [DOI] [PMC free article] [PubMed] [Google Scholar]
