Cloning and characterization of human complement component C7 promoter.
To study the transcriptional regulation of the human complement component C7, a 1 kb promoter fragment was cloned and the transcription start site was determined. C7 is expressed by the hepatoma-derived cell line Hep-3B, but not by Hep-G2. Transfection of these cell lines with different C7 promoter-luciferase constructs demonstrated that 1 kb of the 5'-flanking region contains the necessary elements for driving C7 transcription in a tissue-specific manner and showed that the sequence between -29/+102 retained the majority of C7 promoter activity in Hep-3B. Electrophoretic mobility shift assays suggested that the binding of the C/EBPalpha transcription factor to a C/EBP sequence located at +42 is essential for C7 expression. To investigate whether the absence of C/EBPalpha expression in Hep-G2 cells is responsible for the lack of C7 transcription, Hep-G2 cells were transfected with a C/EBPalpha expression vector. C/EBPalpha transactivated the C7 luciferase reported gene and restored the C7 expression in Hep-G2 cells.
González
S
S
Functional Biology Department, University of Oviedo, Spain.
Martínez-Borra
J
J
López-Larrea
C
C
D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods*; D003184:Complement C7 / Q000737:chemistry / Q000235:genetics*; D005786:Gene Expression Regulation / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D014407:Tumor Cells, Cultured
D003184:Complement C7