Tissue-specific interactions between nuclear proteins and the aminopeptidase N promoter.
Aminopeptidase N/CD13 is a metallopeptidase found in many tissues. Aminopeptidase N activity is high in the small intestinal mucosa, moderate in the liver, and low in the spleen. Using DNase I footprinting and electrophoretic mobility shift assays with nuclear extracts from these tissues, three cis elements (DF, LF-B1, UF) were identified in the aminopeptidase N promoter. The DF region (-53 to -30) interacts with the ubiquitously expressed transcription factor Sp1. The LF-B1 region (-85 to -58) interacts with the liver transcription factor LF-B1 (HNF-1) which was detected as well in nuclei from small intestinal mucosa. The UF region (-112 to -90) interacts with nuclear factors which seem to be expressed differentially in the liver and the small intestine. Transfection of promoter deletions into HepG2 cells showed that the LF-B1 region is necessary for high expression of the aminopeptidase N gene in liver cells. LF-B1 could not be detected in spleen nuclei. In accordance with this, RNA analysis demonstrated that the aminopeptidase N promoter operating in the small intestine and in the liver is inactive in the spleen. In this tissue initiation of transcription from the aminopeptidase N gene occurs from an upstream promoter.
Department of Biochemistry C, University of Copenhagen, Denmark.
J
J
Olsen
L
L
Laustsen
U
U
Kärnström
H
H
Sjöström
O
O
Norén
D000626:Aminopeptidases / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D018826:CD13 Antigens; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D016172:DNA Fingerprinting; D006031:Glycosylation; D006801:Humans; D007421:Intestine, Small / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D008113:Liver Neoplasms / Q000473:pathology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012334:RNA, Neoplasm / Q000235:genetics; D013154:Spleen / Q000201:enzymology; D013552:Swine; D014157:Transcription Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
D009687:Nuclear Proteins; D012334:RNA, Neoplasm; D014157:Transcription Factors; D000626:Aminopeptidases; D018826:CD13 Antigens