Conversion of big endothelin-1 to endothelin-1 by phosphoramidon-sensitive metalloproteinase derived from aortic endothelial cells.
When big endothelin-1 (big ET-1, 1-39) was incubated with the membrane fraction obtained from cultured endothelial cells (ECs) at pH 7.0 for 6 h, the immunoreactive (ir) ET in the reaction mixture was markedly increased. Phosphoramidon, a metalloproteinase inhibitor, as well as metal chelators specifically suppressed the above increase. Using reverse-phase high-performance liquid chromatography, ir-ET was confirmed to be ET-1[1-21]. In addition, we noted that the alterations in ET-1 correlated with those in the C-terminal fragment (CTF, 22-39) of big ET-1. When cultured ECs were incubated with phosphoramidon, time-dependent secretion of ET-1 and CTF from the cells was markedly suppressed. In contrast, the secretion of big ET-1 was increased by phosphoramidon. Thiorphan, a specific inhibitor of neutral endopeptidase 24.11, was without effect on the secretion of ET-related peptides. Moreover, phosphoramidon potently inhibited the hypertensive effect of big ET-1 without affecting the ET-1-induced hypertension in anesthetized rats. From these findings, it seems reasonable to consider that phosphoramidon-sensitive and membrane-bound metalloproteinase, which is not a neutral endopeptidase 24.11, is the most plausible candidate for big ET-1-converting enzyme in vivo.
Matsumura
Y
Y
Department of Pharmacology, Osaka University of Pharmaceutical Sciences, Japan.
Ikegawa
R
R
Hisaki
K
K
Tsukahara
Y
Y
Takaoka
M
M
Morimoto
S
S
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D019332:Endothelin-1; D016232:Endothelins / Q000378:metabolism*; D004727:Endothelium / Q000166:cytology / Q000201:enzymology*; D006020:Glycopeptides / Q000494:pharmacology*; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000201:enzymology; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D019332:Endothelin-1; D016232:Endothelins; D006020:Glycopeptides; D011498:Protein Precursors; D008666:Metalloendopeptidases; C008890:phosphoramidon