title: Cryptide signaling: Amphiphilic peptide-induced exocytotic mechanisms in mast cells.
abstract: Amphiphilic peptides with positive charges such as substance P (SP) and mastoparan (MP) are known to induce exocytosis in rat peritoneal mast cells. To elucidate whether and how intracellular Ca(2+) signaling is involved in the peptide-induced exocytosis, here we investigated the relationships between an increase in intracellular free Ca(2+) concentration ([Ca(2+)](i)) and exocytosis caused by SP and MP. SP and MP induced exocytosis coinciding with an initial rapid and transient [Ca(2+)](i) increase, but not with a sustained increase. These stimulations were abolished by pertussis toxin, indicating the involvement of the G(i)-family of G proteins in the peptide signaling. Moreover, the [Ca(2+)](i) increase was shown to accelerate and potentiate exocytosis, suggesting that the transient increase in [Ca(2+)](i) positively modified exocytotic secretion. However, it was indicated that the signal of [Ca(2+)](i) increase was not sufficient for the peptide-induced exocytosis, suggesting the participation of alternative mechanisms other than Ca(2+) signaling in the pathway.
authors.affiliation: Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan. hmukai-endo@umin.ac.jp
authors.forename: Hidehito
authors.initials: H
authors.lastname: Mukai
authors.forename: Miharu
authors.initials: M
authors.lastname: Kikuchi
authors.forename: Shigetomo
authors.initials: S
authors.lastname: Fukuhara
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kiso
authors.forename: Eisuke
authors.initials: E
authors.lastname: Munekata
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D005089:Exocytosis / Q000187:drug effects*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism; D015288:Neurokinin A / Q000494:pharmacology; D015287:Neurokinin B / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D010537:Peritoneum / Q000166:cytology / Q000187:drug effects; D037342:Pertussis Toxin / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000494:pharmacology*; D014862:Wasp Venoms / Q000494:pharmacology*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014862:Wasp Venoms; D013373:Substance P; C037500:mastoparan; D015288:Neurokinin A; D015287:Neurokinin B; D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D002118:Calcium