Histones and basic polypeptides activate Ca2+/cation influx in various cell types.
Histone H2A (1-10 microg/ml) added to Ehrlich ascite cell suspensions promoted: (i) Ca2+ influx, but no apparent intracellular Ca2+ mobilization; (ii) plasma-membrane depolarization and Na+ influx in Ca2+-free medium, which were recovered by Ca2+ readmission; (iii) influx of other cations such as Ba2+, Mn2+, choline+ and N-methyl-d-glucamine+, but not of propidium+, ethidium bromide and Trypan Blue. H2A-induced Ca2+ influx and cell depolarization were: (i) blocked by La3+ and Gd3+, but not by various inhibitors of receptor-activated Ca2+-influx pathways/channels; (ii) mimicked by various basic polypeptides, with Mr>4000; (iii) prevented or reversed by polyanions such as polyglutamate or heparin; (iv) present in other cell types, such as Jurkat, PC12 and Friend erythroleukaemia cells, but virtually absent from rat hepatocytes and thymocytes. We conclude that cationic proteins/polypeptides, by interacting in a cell-specific manner with the cell surface, can activate in those cells putative non-selective Ca2+ channels and membrane depolarization.
Gamberucci
A
A
Institute of General Pathology, University of Siena, 53100-Siena, Italy.
Fulceri
R
R
Marcolongo
P
P
Pralong
W F
WF
Benedetti
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology; D002286:Carcinoma, Ehrlich Tumor; D002412:Cations; D002478:Cells, Cultured; D006657:Histones / Q000494:pharmacology*; D006801:Humans; D019169:Jurkat Cells; D004915:Leukemia, Erythroblastic, Acute; D008099:Liver; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D016716:PC12 Cells; D051381:Rats; D017207:Rats, Sprague-Dawley; D013950:Thymus Gland; D014407:Tumor Cells, Cultured
D015220:Calcium Channels; D002412:Cations; D006657:Histones; D002118:Calcium