Effects of mastoparan and related peptides on phosphoinositide breakdown in HL-60 cells and cell-free preparations.
In differentiated HL-60 cells the amphiphilic peptide mastoparan induces a dose-dependent stimulation of phosphoinositide breakdown with an EC50 value of 9 microM. Such stimulation can be markedly reduced by pretreatment of the cells with pertussis toxin (100 ng/ml, 2 h). In membranes obtained from differentiated HL-60 cells, guanine nucleotides stimulate the formation of IP2 and IP3. Calcium ions also induce phosphoinositide breakdown in this preparation independent of the presence of guanine nucleotides. In HL-60 cell membranes, mastoparan inhibited GTP gamma S-stimulation of phosphoinositide breakdown with an IC50 value of 3 microM. Such inhibitory activity of mastoparan also was present in membranes from cells pretreated with pertussis toxin. Calcium-induced stimulation of phosphoinositide breakdown was not significantly inhibited by mastoparan. The analogs mastoparan-X and polistes mastoparan had similar inhibitory activity, whereas the analog des-Ile1-Asn2-mastoparan was inactive. In permeabilized HL-60 cells mastoparan also inhibited phosphoinositide breakdown. Another amphiphilic peptide, melittin, was inactive in HL-60 intact cells, but similar to mastoparan, inhibited guanine nucleotide-induced phosphoinositide breakdown in HL-60 cell membranes and permeabilized cells. Thus, mastoparan peptides can stimulate phosphoinositide breakdown in intact HL-60 cells, probably through the interaction with a guanine nucleotide binding protein. In permeabilized cells and in cell membranes, mastoparan induces inhibition of guanine nucleotide-mediated phosphoinositide breakdown presumably through an interaction with an intracellular site. The inhibitory action of mastoparan and melittin is probably related to the amphiphilic character of these peptides.
Gusovsky
F
F
Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, MD 20892.
Soergel
D G
DG
Daly
J W
JW
D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002474:Cell-Free System / Q000378:metabolism; D006150:Guanine Nucleotides / Q000494:pharmacology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007942:Leukemia, Experimental / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D008555:Melitten / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D010716:Phosphatidylinositols / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000187:drug effects; D014862:Wasp Venoms / Q000494:pharmacology*
D006150:Guanine Nucleotides; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D010716:Phosphatidylinositols; D014862:Wasp Venoms; D008555:Melitten; C037500:mastoparan; C071123:mastoparan X; C071124:polistes mastoparan; D010738:Type C Phospholipases