title: Inhibition of basic secretagogue-induced signaling in mast cells by cell permeable G alpha i-derived peptides.
abstract: BACKGROUND
  Basic secretagogues of connective tissue mast cells act as receptor mimetic agents that trigger mast cells by activating G proteins. This leads to simultaneous propagation of two signaling pathways: one that culminates in exocytosis, while the other involves protein tyrosine phosphorylation and leads to release of arachidonic acid metabolites. We have previously shown that introduction of a peptide that comprises the C-terminal end of G alpha i3 into permeabilized mast cells inhibits basic secretagogue-induced exocytosis [Aridor et al., Science 1993;262:1569-1572]. We investigated whether cell-permeable peptides, composed of the C-terminus of G alpha i3 fused with importation sequences, affect mast cell function.
  
  
  METHODS
  Following preincubation with the fused peptides, rat peritoneal mast cells were activated by compound 48/80 and analyzed for histamine and prostaglandin D2 release and protein tyrosine phosphorylations.
  
  
  RESULTS
  We demonstrate that out of three importation sequences tested only G alpha i3 peptide fused with the Kaposi fibroblast growth factor importation sequence (ALL1) inhibited release of histamine. ALL1 as well as a cell-permeable peptide that corresponds to G alpha i2 also blocked compound 48/80-stimulated protein tyrosine phosphorylation, though the latter did not block histamine release. ALL1 effect was G protein-specific, as it was incapable of blocking protein tyrosine phosphorylation stimulated by pervanadate.
  
  
  CONCLUSIONS
  ALL1, a transducible G alpha i3-corresponding peptide, blocks the two signaling pathways in mast cells: histamine release and protein tyrosine phosphorylation. Cell permeable peptides that block these two signaling cascades may constitute a novel approach for preventing the onset of the allergic reaction.
authors.affiliation: Allergene Ltd., Ramat Gan, Israel.
authors.forename: Irit
authors.initials: I
authors.lastname: Shefler
authors.forename: Orly
authors.initials: O
authors.lastname: Zavaro
authors.forename: Tamar
authors.initials: T
authors.lastname: Raz
authors.forename: Dana
authors.initials: D
authors.lastname: Baram
authors.forename: Ronit
authors.initials: R
authors.lastname: Sagi-Eisenberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002463:Cell Membrane Permeability; D004353:Drug Evaluation, Preclinical; D051960:GTP-Binding Protein alpha Subunit, Gi2 / Q000494:pharmacology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000494:pharmacology*; D006636:Histamine Release / Q000187:drug effects; D018836:Inflammation Mediators / Q000502:physiology*; D039661:Integrin beta3 / Q000737:chemistry; D008407:Mast Cells / Q000187:drug effects* / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology; D010455:Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D015230:Prostaglandin D2 / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D015293:Transducin / Q000494:pharmacology; D003189:p-Methoxy-N-methylphenethylamine / Q000037:antagonists & inhibitors
chemical_list: C526440:ALL1 peptide; D018836:Inflammation Mediators; D039661:Integrin beta3; D010446:Peptide Fragments; D010455:Peptides; D003189:p-Methoxy-N-methylphenethylamine; D051960:GTP-Binding Protein alpha Subunit, Gi2; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; C498017:Gnai2 protein, rat; C498820:Gnai3 protein, rat; D015293:Transducin; D015230:Prostaglandin D2