Mast cell adenosine induced calcium mobilization via Gi3 and Gq proteins.
Adenosine is an important mediator of mast cell secretory responses. Adenosine appears to act through one or more adenosine receptor subtypes to activate several signal transduction pathways; however, the specific mechanisms involved are not clearly defined. We studied the pathways involved in adenosine receptor-mediated calcium fluxes in RBL-2H3 cells, a mucosal mast cell-like line. The role of endogenous heterotrimeric G proteins in adenosine mediated calcium mobilization was investigated by microinjection of inhibitory antibodies that block specific G protein subtype function. The calcium transients associated with adenosine and antigen stimulation were compared in noninjected cells and cells that were microinjected with affinity purified neutralizing antibodies to the alpha subunits of Gi3, Gq, or Gs. The percentage of cells responding to adenosine was decreased in the presence of antibodies to Gi3 and Gq, but not Gs. Pertussis toxin decreased the percentage of cells responding to adenosine, but not antigen. These studies demonstrated a functional requirement for the pertussis toxin sensitive Gi3 protein and the pertussis toxin insensitive Gq protein in adenosine mediated calcium mobilization in mast cells.
Hoffman
H M
HM
Department of Medicine, University of California, San Diego School of Medicine, La Jolla 92093, USA.
Walker
L L
LL
Marquardt
D L
DL
D000241:Adenosine / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D001854:Bone Marrow Cells; D002118:Calcium / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000502:physiology*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000502:physiology*; D006168:Guinea Pigs; D015471:Leukemia, Basophilic, Acute; D008407:Mast Cells / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D037342:Pertussis Toxin; D051381:Rats; D018047:Receptors, Purinergic P1 / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D014407:Tumor Cells, Cultured; D010566:Virulence Factors, Bordetella / Q000633:toxicity
D018047:Receptors, Purinergic P1; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs; D000241:Adenosine; D002118:Calcium