Induction of cytosolic Ca2+ elevation mediated by Mas-7 occurs through membrane pore formation.
Mas-7, a mastoparan derivative, induces elevation of intracellular free Ca2+ concentration ([Ca2+]i) along two independent pathways. The minor contribution occurs via phospholipase C activation and is negatively regulated by treatment with phorbol 12-myristate 13-acetate, a protein kinase C activator. The major contribution involves plasma membrane pores allowing not only Ca2+, Mn2+, and Na+ to enter but also the uptake of ethidium bromide (314 Da) and lucifer yellow (457 Da), but not fura-2 (831 Da), Evans blue (961 Da), and fluorescein-conjugate phalloidin (1,175 Da). Mas-7-induced current, as measured in planar lipid bilayers, reveals that Mas-7-induced pores have two slope conductances, 290 and 94 pS, and that the pores are nonselective for cations. The results also indicate that Mas-7 can produce pores by direct interaction with the plasma membrane without the involvement of membrane proteins and cytosolic factors. Besides in human neuroblastoma cells, similar Mas-7 effects were also observed in other cell lines such as HL-60, 1321N1 human astrocytoma, and bovine chromaffin cells. The data suggest that the Mas-7-induced [Ca2+]i elevation is the combined result of Ca2+ release from stores via phosphoinositide turnover and prolonged Ca2+ influx through membrane pores.
Suh
B C
BC
Department of Life Science and Basic Science Research Institute, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea.
Song
S K
SK
Kim
Y K
YK
Kim
K T
KT
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D007473:Ion Channels; D008051:Lipid Bilayers / Q000737:chemistry; D008345:Manganese / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D010455:Peptides / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism; D011493:Protein Kinase C / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D012964:Sodium / Q000378:metabolism; D013329:Structure-Activity Relationship; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014862:Wasp Venoms / Q000737:chemistry / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D036341:Intercellular Signaling Peptides and Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; C084070:Mas7 protein, synthetic; D010455:Peptides; D010716:Phosphatidylinositols; D014862:Wasp Venoms; D008345:Manganese; D019284:Thapsigargin; C037500:mastoparan; D015544:Inositol 1,4,5-Trisphosphate; D012964:Sodium; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D000252:Calcium-Transporting ATPases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium