Conversion of big endothelin-1 to endothelin-1 by two-types of metalloproteinases of cultured porcine vascular smooth muscle cells.
Incubation of big endothelin-1 (big ET-1, 1-39) with the membrane fraction obtained from cultured vascular smooth muscle cells (VSMCs) resulted in an increase in immunoreactive-ET (IR-ET), which was inhibited by EDTA but not by phosphoramidon, a metalloproteinase inhibitor. When the incubation was performed in the presence of N-ethylmaleimide (NEM), the generation of IR-ET was markedly augmented and this augmentation was abolished by phosphoramidon. The pH profile for IR-ET generation in the presence of NEM was apparently distinct from that observed in the absence of NEM. Reverse-phase HPLC of the incubation mixture with or without NEM revealed one major IR-ET component corresponding to the elution position of synthetic ET-1 (1-21). When the cultured VSMCs were incubated with big ET-1, a conversion to the mature ET-1 was observed. This ET-1 generation from exogenously applied big ET-1 was markedly inhibited by the addition of phosphoramidon, although the inhibitor did not influence the basal secretion of ET-1-like materials. These results suggest the presence of two types of metalloproteinases, which can generate ET-1, in VSMCs. The possibility that ET-1 functions in an autocrine manner to control the cardiovascular system warrants further attention.
Matsumura
Y
Y
Department of Pharmacology, Osaka University of Pharmaceutical Sciences, Japan.
Ikegawa
R
R
Tsukahara
Y
Y
Takaoka
M
M
Morimoto
S
S
D000818:Animals; D001011:Aorta / Q000201:enzymology; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D019332:Endothelin-1; D016232:Endothelins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008666:Metalloendopeptidases / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011863:Radioimmunoassay; D013552:Swine
D019332:Endothelin-1; D016232:Endothelins; D007527:Isoenzymes; D011498:Protein Precursors; D008666:Metalloendopeptidases