Cloning of the rat insulin-like growth factor binding protein-1 gene and analysis of its 5' promoter region.

To understand specific mechanisms involved in the regulation of insulin-like growth factor binding protein-1 (IGFBP-1), an important modulator of IGF bioactivity, we cloned the rat IGFBP-1 gene and sequenced a 1.5 kb Sph1-Sph1 fragment containing 1110 bases upstream from the translation start site. Computer analysis reveals the presence of ATA, CACCC, and CCAAT elements, and putative homeodomain, AP-1, insulin and glucocorticoid response elements in the 5' promoter. Primer extension and ribonuclease protection studies reveal a single cap site in RNA from rat hepatoma cells and both control and diabetic rat liver.     

Cloning of the hamster p16 gene 5' upstream region and its aberrant methylation patterns in pancreatic cancer

The hamster model of pancreatic carcinogenesis is useful for understanding the development of human pancreatic cancer. However, there is only a small amount of hamster genetic information available for analyzing the gene alterations in hamster pancreatic cancers. Here, we determined the nucleotide sequence of the 5' upstream region of the hamster p16 gene using a suppression polymerase chain reaction method combined with gene-specific primers. Based on this sequence, we analyzed the methylation status of the 5' region by bisulfite sequencing in three normal pancreatic tissues and five pancreatic duct adenocarcinomas (PDAs). All five PDAs were highly methylated in the 5' upstream region and showed reduced expressions of the p16 gene, while the three normal samples were demethylated. The method described in this study is a highly effective and rapid technique for determining the 5' upstream region, and is applicable to epigenetic studies of the methylation status of this region.     

A liver-specific chromatin protein binding to the 5' far upstream region of the rat serum albumin gene

Chromatin proteins which were extracted with 0.3 M NaCl from rat liver, brain, and kidney nuclei were examined by the protein blotting technique for their ability to bind to the 5' upstream regions of the rat serum albumin gene. A 110-kDa protein from liver nuclei bound specifically to the most upstream fragment (between approximately equal to -7.3 kbp and -2.0 kbp from the cap site) of the cloned albumin genomic DNA, whereas no proteins from kidney and brain bound to this fragment. It is possible that the 110-kDa protein is concerned with the tissue-specific expression of the albumin gene.     

Cloning and analysing of 5‘ flanking region of Xenopus organizer gene noggin

Xenopus organizer specific gene noggin possesses nearly all the characterestic properties of the action of organizer to specify the embryonic body acis.To analyze how the maternal inherited factors control its expression pattern,we cloned the 5‘ regulatory region of noggin gene.The 1.5 kb upstream sequense could direct reporter gene to express in vivo and data from deletion analysis indicated that a 229 base pair fragmet is essential for activating noggin expression.We further demonstrated that the response elements within this regulatory region were indeed under the control of growth factor activin and Wnt signaling pathway components.     

Characterization of the 5' flanking region of rat glucokinase gene

The rat glucokinase (GK) gene containing the first exon was isolated and its 5' flanking region was characterized by the bacterial chloramphenicol acetyltransferase (CAT) assay. A transient expression assay with a series of 5' deletion constructs (-5.5 k to -48) of GK-CAT fusion genes indicated that the 5' flanking sequence up to nucleotide -87 was sufficient for promoter activity in adult rat hepatocytes, but its activity was much weaker than that of the SV40 enhancer/promoter. Similar promoter activity was also detected in dRLh-84 hepatoma cells, which do not express glucokinase. Insulin treatment caused no change in the CAT activity of hepatocytes transfected with the fusion genes. These results suggest that the 5' flanking region of the glucokinase gene up to -5.5 k does not contain enhancer elements responsible for tissue-specific expression or insulin regulation.