[Molecular aspects of the expression and regulation of endothelial nitric oxide synthase]

The endothelial isoform of nitric oxide synthase (eNOS) ensures enzymatic production of nitric oxide (NO) not only in endothelial cells but also in other cell types, such as neurons, platelets, and some epithelial cells. Its physiological role has been well defined in some of these cells, such as relaxation of vascular smooth muscle cells, or long-term potentiation in neurons, owing to knockout experiments. Although constitutively expressed in endothelial cells, eNOS mRNA has been shown to be modulated by several physical, biochemical, and hormonal factors, acting at the transcriptional or post-transcriptional levels. Several functional regulatory elements have been mapped in the eNOS promoter, active both in endothelial and non-endothelial cells, and we present elements demonstrating that these elements are not sufficient to explain the high level of eNOS expression specific to endothelial cells.