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Characterization of the human C6 promoter: requirement of the CCAAT enhancer binding protein binding site for C6 gene promoter activity.
J Immunol. 1996 Sep 15; 157(6):2282-90.JI

Abstract

The sixth complement component (C6) is a late-acting complement protein that participates in the assembly of the membrane attack complex. C6 and most of the complement proteins are mainly synthesized in the liver. However, the human hepatoma-derived cell line Hep-G2, which produces the majority of complement proteins, synthesizes traces of C6. Here, we have isolated and characterized the human C6 promoter. Approximately 1 kb of C6 upstream sequence is shown to be sufficient to achieve tissue-specific expression of a luciferase reporter gene in two hepatic (Hep-G2 and Hep-3B) and two extrahepatic cell lines (fibroblast M1 and HeLa) in a manner similar to endogenous C6. There are wide differences in C6 mRNA expression among the four cell lines, whereas Hep-3B expresses high levels of C6, Hep-G2 and M1 poorly synthesize C6, and HeLa completely lacks C6 expression. Deletional and mutational analysis demonstrates that a C/EBP (CCAAT/enhancer binding protein) site located at -67 is required for C6 expression in Hep-3B cells, but it has little effect in M1 and Hep-G2 cells. Electrophoretic mobility shift assays show that this sequence binds to a C/EBP alpha using Hep-3B nuclear extract, but a negligible activity is detected using a Hep-G2 extract. To further investigate whether C/EBP alpha is the limiting factor for C6 expression, we have transfected a C/EBP alpha expression vector into Hep-G2 and Ml cells. C/EBP alpha expression vector dramatically trans-activates the luciferase reporter gene controlled by the C6 promoter, and it partially restores C6 mRNA expression in Hep-G2 cells.

Authors+Show Affiliations

Immunology Service, Central Hospital of Asturias, Oviedo, Spain.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8805625

Citation

González, S, and C López-Larrea. "Characterization of the Human C6 Promoter: Requirement of the CCAAT Enhancer Binding Protein Binding Site for C6 Gene Promoter Activity." Journal of Immunology (Baltimore, Md. : 1950), vol. 157, no. 6, 1996, pp. 2282-90.
González S, López-Larrea C. Characterization of the human C6 promoter: requirement of the CCAAT enhancer binding protein binding site for C6 gene promoter activity. J Immunol. 1996;157(6):2282-90.
González, S., & López-Larrea, C. (1996). Characterization of the human C6 promoter: requirement of the CCAAT enhancer binding protein binding site for C6 gene promoter activity. Journal of Immunology (Baltimore, Md. : 1950), 157(6), 2282-90.
González S, López-Larrea C. Characterization of the Human C6 Promoter: Requirement of the CCAAT Enhancer Binding Protein Binding Site for C6 Gene Promoter Activity. J Immunol. 1996 Sep 15;157(6):2282-90. PubMed PMID: 8805625.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Characterization of the human C6 promoter: requirement of the CCAAT enhancer binding protein binding site for C6 gene promoter activity. AU - González,S, AU - López-Larrea,C, PY - 1996/9/15/pubmed PY - 1996/9/15/medline PY - 1996/9/15/entrez SP - 2282 EP - 90 JF - Journal of immunology (Baltimore, Md. : 1950) JO - J Immunol VL - 157 IS - 6 N2 - The sixth complement component (C6) is a late-acting complement protein that participates in the assembly of the membrane attack complex. C6 and most of the complement proteins are mainly synthesized in the liver. However, the human hepatoma-derived cell line Hep-G2, which produces the majority of complement proteins, synthesizes traces of C6. Here, we have isolated and characterized the human C6 promoter. Approximately 1 kb of C6 upstream sequence is shown to be sufficient to achieve tissue-specific expression of a luciferase reporter gene in two hepatic (Hep-G2 and Hep-3B) and two extrahepatic cell lines (fibroblast M1 and HeLa) in a manner similar to endogenous C6. There are wide differences in C6 mRNA expression among the four cell lines, whereas Hep-3B expresses high levels of C6, Hep-G2 and M1 poorly synthesize C6, and HeLa completely lacks C6 expression. Deletional and mutational analysis demonstrates that a C/EBP (CCAAT/enhancer binding protein) site located at -67 is required for C6 expression in Hep-3B cells, but it has little effect in M1 and Hep-G2 cells. Electrophoretic mobility shift assays show that this sequence binds to a C/EBP alpha using Hep-3B nuclear extract, but a negligible activity is detected using a Hep-G2 extract. To further investigate whether C/EBP alpha is the limiting factor for C6 expression, we have transfected a C/EBP alpha expression vector into Hep-G2 and Ml cells. C/EBP alpha expression vector dramatically trans-activates the luciferase reporter gene controlled by the C6 promoter, and it partially restores C6 mRNA expression in Hep-G2 cells. SN - 0022-1767 UR - https://www.unboundmedicine.com/medline/citation/8805625/Characterization_of_the_human_C6_promoter:_requirement_of_the_CCAAT_enhancer_binding_protein_binding_site_for_C6_gene_promoter_activity_ L2 - https://www.jimmunol.org/lookup/pmidlookup?view=long&pmid=8805625 DB - PRIME DP - Unbound Medicine ER -