CLONING AND STRUCTURAL CHARACTERIZATION OF THE HUMAN ENDOTHELIAL NITRIC-OXIDE-SYNTHASE GENE

Nitric oxide accounts for the activity of endothelium-derived relaxing factor, which seems to have an important role in vasodilation and inhibition of platelet aggregation. In endothelial cells, one isoform of nitric-oxide synthase is constitutively expressed. Analysis of the cDNA encoding the human endothelial nitric-oxide synthase revealed that the mRNA is 4.1 kb in size and that the translated protein consists of 1203 amino acids. We have cloned a genomic DNA encoding the human endothelial nitric-oxide synthase and analyzed the entire nucleotide sequence of the gene. The gene consists of 26 exons with a total size of 21 kb. The 5' flanking region of the gene lacks TATA boxes, but it contains putative Sp1-binding sites in (G+C)-rich regions. Of particular interest is the fact that a shear-stress-responsive element is located at position -985, which probably regulates the nitric-oxide-synthase gene in response to fluid mechanical forces at the transcriptional level in the vascular endothelium. Two minisatellite sequences are detectable in introns 2 and 8; a 32-bp consensus sequence repeats 38 times and a 57-bp consensus sequence repeats ten times. We found polymorphisms of the BamHI fragment containing the former minisatellite sequence in genomic DNA from pedigree family members. Furthermore, five tandem repeats of a 27-bp core consensus sequence and 35 repeats of a dinucleotide (CA) are located in introns 4 and 13, respectively. These repeat sequences will probably provide genetic markers for gene mapping and linkage analysis of inherited diseases including cardiovascular diseases.