[Effect of discodermin A, an antimicrobial peptide, on the cytoplasm membrane].
The effects of discodermin A, an antimicrobial peptide extracted from sea sponge Discodermia kiiensis, on cell membranes were investigated using vascular smooth muscle cells and erythrocytes. At lower concentrations (0.1-3 microM), discodermin A increased muscle tension with an increase in intracellular free Ca2+ concentration ([Ca2+]i) indicated by the fluorescence of Ca2+ indicator, fura-PE3, in rat aortic smooth muscle. On the other hand, the higher concentration of discodermin A (10-30 microM) accelerated the leakage of loaded fura-PE3 from cells. In rabbit mesenteric artery treaded with discodermin A, addition of micromolar concentration of Ca2+ evoked contraction in the presence of ATP, suggesting that permeability of the membrane to Ca2+ and ATP is increased by discodermin A. Confocal fluorescence microscopy showed that discodermin A permeabilized the plasma membrane of A10 cells to fluorescent agents EthD-1 and the intracellular esterase coupled with another fluorescent agent calcein. Discodermin A also showed a hemolytic effect on rabbit erythrocytes, suggesting that discodermin A permitted transmembrane passage of hemoglobin. These results suggest that discodermin A form pores of different sizes on the cytoplasm membrane in concentration- and time-dependent manners. Discodermin A may be a saponin-like bioactive peptide.
Sato
K
K
Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Japan.
Horibe
K
K
Saito-Mitsui
M
M
Hori
M
M
Matsunaga
S
S
Fusetani
N
N
Ozaki
H
H
Karaki
H
H
D029845:Amphibian Proteins; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D016257:Fura-2 / Q000031:analogs & derivatives / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D010455:Peptides / Q000302:isolation & purification / Q000494:pharmacology*; D011161:Porifera / Q000737:chemistry*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar
D029845:Amphibian Proteins; D023181:Antimicrobial Cationic Peptides; D010455:Peptides; C098106:fura-PE3; C045398:discodermin A, Discodermia kiiensis; D002118:Calcium; D016257:Fura-2