Human polymorphonuclear leukocytes generate and degrade endothelin-1 by two distinct neutral proteases.
Human polymorphonuclear leukocytes (PMNs, 4 x 10(6)/ml) converted human big endothelin (bET) to an endothelin-1 (ET-1)-like contractile factor, as assessed by bioassay. The formation of this ET-1-like activity from bET was partially inhibited by phosphoramidon (54 micrograms/ml), but not by pepstatin-A (1 microgram/ml), epoxysuccinyl-L-leucylamido(guanidino)butane (E-64, 10 micrograms/ml) or phenylmethylsulfonyl fluoride (PMSF, 25 micrograms/ml). In addition, nonactivated PMNs converted [125I]bET to [125I]ET-1, thus confirming the bioassay results. Incubation of ET-1 with fMLP-activated PMNs or cell-free supernatants from activated PMNs resulted in the loss of its contractile activity, and this loss of activity was paralleled by the metabolism of [125I]ET-1. The metabolism of [125I]ET-1 by PMNs or leukocyte cathepsin G (5 micrograms/ml) was prevented by PMSF (25 micrograms/ml), but not by phosphoramidon (54 micrograms/ml) or pepstatin-A (1 microgram/ml). Thus, PMNs can form ET-1 from bET via a neutral protease and degrade ET-1 via a serine protease, an observation that may have important pathophysiologic implications in disease states associated with PMN infiltration.
Sessa
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WC
William Harvey Research Institute, St Bartholomew's Hospital Medical College, London, U.K.
Kaw
S
S
Zembowicz
A
A
Anggård
E
E
Hecker
M
M
Vane
J R
JR
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D010450:Endopeptidases / Q000378:metabolism*; D019332:Endothelin-1; D016232:Endothelins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009504:Neutrophils / Q000201:enzymology*; D011480:Protease Inhibitors / Q000494:pharmacology; D011498:Protein Precursors / Q000378:metabolism*; D011817:Rabbits
D019332:Endothelin-1; D016232:Endothelins; D011480:Protease Inhibitors; D011498:Protein Precursors; D010450:Endopeptidases