Heterotrimeric G protein Gi is involved in a signal transduction pathway for ATP release from erythrocytes.
Erythrocytes are reported to release ATP in response to mechanical deformation and decreased oxygen tension. Previously we proposed that receptor-mediated activation of the heterotrimeric G protein G(s) resulted in ATP release from erythrocytes. Here we investigate the hypothesis that activation of heterotrimeric G proteins of the G(i) subtype are also involved in a signal transduction pathway for ATP release from rabbit erythrocytes. Heterotrimeric G proteins G(alphai1), G(alphai2), and G(alphai3) but not G(alphao) were identified in rabbit and human erythrocyte membranes. Pretreatment of rabbit erythrocytes with pertussis toxin (100 ng/ml, 2 h), which uncouples G(i/o) from their effector proteins, inhibited deformation-induced ATP release. Incubation of rabbit and human erythrocytes with mastoparan (Mas, 10 microM) or Mas-7 (1 microM), which are compounds that directly activate G(i) proteins, resulted in ATP release. However, rabbit erythrocytes did not release ATP when incubated with Mas-17 (10 microM), which is an inactive Mas analog. In separate experiments, Mas (10 microM) but not Mas-17 (10 microM) increased intracellular concentrations of cAMP when incubated with rabbit erythrocytes. Importantly, Mas-induced ATP release from rabbit erythrocytes was inhibited after treatment with pertussis toxin (100 ng/ml, 2 h). These data are consistent with the hypothesis that the heterotrimeric G protein G(i) is a component of a signal transduction pathway for ATP release from erythrocytes.
Olearczyk
Jeffrey J
JJ
Dept. of Pharmacological and Physiological Science, St. Louis Univ. School of Medicine, M-208, St. Louis, MO 63104, USA. olearcjj@slu.edu
Stephenson
Alan H
AH
Lonigro
Andrew J
AJ
Sprague
Randy S
RS
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D004907:Erythrocyte Deformability / Q000502:physiology; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D010455:Peptides / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D011817:Rabbits; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D036341:Intercellular Signaling Peptides and Proteins; C084070:Mas7 protein, synthetic; D010455:Peptides; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019206:GTP-Binding Protein alpha Subunits, Gi-Go