Expression of endothelial nitric oxide synthase in human peritoneal tissue: Regulation by Escherichia coli lipopolysaccharide

Changes in the expression of endothelial nitric oxide synthase (eNOS) in th e peritoneum could be involved in the peritoneal dysfunction associated wit h peritoneal inflammation. Demonstrated recently in bovine endothelial cell s was the existence of cytosolic proteins that bind to the 3'-untranslated region (3'-UTR) of eNOS mRNA and could be implicated in eNOS mRNA stabiliza tion. The present work demonstrates that eNOS protein is expressed in human endothelial and mesothelial peritoneal cells. Escherichia coli lipopolysac charide shortened the half-life of eNOS message, reducing eNOS protein expr ession in peritoneal mesothelial and endothelial cells. Moreover, under bas al conditions, human peritoneal samples expressed cytosolic proteins that b ind to the 3'-UTR of eNOS mRNA. The cytosolic proteins that directly bind t o 3'-UTR were identified as a 60-kD protein. After incubation of human peri toneal samples with lipopolysaccharide, the binding activity of the cytosol ic 60-kD protein increased in a time-dependent manner. Studies are now nece ssary to determine the involvement of this 60-kD protein in the regulation of eNOS expression in peritoneal cells and particularly its involvement in the peritoneal dysfunction associated with inflammatory reactions.