Cell-specific expression of mouse albumin promoter. Evidence for cell-specific DNA elements within the proximal promoter region and cis-acting DNA elements upstream of -160.
Regulation of albumin gene expression is believed to be mediated by multiple nuclear factors that interact with cis-acting DNA sequences within the first 160 base pairs (bp) of the promoter. The minimal promoter sequence required to generate tissue-specific expression has not been clearly defined. We have constructed a series of transient expression vectors containing progressive deletions of the mouse albumin gene 5'-flanking sequence fused to the bacterial chloramphenicol acetyltransferase (CAT) gene and include the Moloney murine leukemia viral (Mo-MuLV) enhancer. Promoter activity was determined in mouse hepatoma and fibroblast cell lines by chloramphenicol acetyltransferase and S1 nuclease analyses. All constructions were compared with -623 Albcat-Mo-MuLV which contains all the sequence homology between the rat and mouse promoters. Low levels of expression were observed with -60 Albcat-Mo-MuLV (10%) in hepatoma but not fibroblast cells. Addition of promoter sequence to -208 bp progressively increased activity to 190% in the hepatoma cells, while -308 and -1612 Albcat-Mo-MuLV had activity similar to the -623 Albcat-Mo-MuLV level, and -3000 Albcat-Mo-MuLV showed a 2-fold reduction in transcriptional activity. The inclusion of promoter sequences upstream of -60 generated low levels of expression in the fibroblasts. We also show that factors from mouse liver nuclear extracts protect at least five regions of the albumin promoter upstream of -160. Our results indicate that tissue specificity is established within the proximal promoter region and that additional cis-acting elements that may have a functional role in the efficiency of albumin gene expression are located upstream of -160 bp.
Izban
M G
MG
Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston 77550.
Papaconstantinou
J
J
D000418:Albumins / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D005822:Genetic Vectors; D008099:Liver / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D009928:Organ Specificity; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid
D000418:Albumins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D015500:Chloramphenicol O-Acetyltransferase