Hydrolysis of atrial and brain natriuretic peptides by the human astrocytoma clone D384 and the neuroblastoma line SH-SY5Y.

The content of membrane peptidases has been compared in the human astrocytoma clone D384 and the human neuroblastoma line SH-SY5Y. Endopeptidase-24.11 (neutral endopeptidase, EC 3.4.24.11) was detectable only on the astrocytoma cells whereas angiotensin-converting enzyme (EC 3.4.15.1) was selectively expressed on the neuroblastoma line. Dipeptidyl peptidase IV (EC 3.4.14.5) was also abundant on the astrocytoma line. The presence of both endopeptidase-24.11 and dipeptidyl peptidase IV on D384 cells was confirmed by immunohistochemistry. A membrane preparation from D384 cells hydrolyzed both atrial natriuretic peptide and brain natriuretic peptide and, in both cases, the pattern of metabolism was similar to that seen with purified endopeptidase-24.11. The endopeptidase-24.11 inhibitor, phosphoramidon, at 1 microM abolished natriuretic peptide metabolism. The neuroblastoma line, which lacked endopeptidase-24.11, failed to metabolise atrial natriuretic peptide and brain natriuretic peptide, emphasizing the key role of the endopeptidase in hydrolyzing these regulatory peptides at the cell surface.