Mechanisms of ATP-induced Ca2+ signaling in osteoclasts.
We investigate the mechanisms underlying the intracellular calcium pulse that occurs in response to extracellular adenosine triphosphate (ATP) in osteoclasts. We find that pre-loading of GDP-beta-S abolishes the response in Ca(2+)-free medium, demonstrating an internal release of Ca2+ via a pathway that involves a G protein. GDP-beta-S does not block in normal Ca(2+)-containing medium, suggesting that ATP also induces a Ca2+ influx across the cell membrane. We confirmed this using the Mn2+ quenching technique, which shows significant opening of Ca2+ channels. We find a smaller response to adenosine diphosphate (ADP) and 2-methylthio-ATP (2-MeSATP), but no response to beta, gamma-methylene-ATP (AMP-PCP), adenosine monophosphate (AMP) or uridine triphosphate (UTP). Prior application of AMP and UTP, but not AMP-PCP, blocks the response to ATP. Our results indicate that the receptor is a P2 subtype that is not characteristic of any previously reported P2 receptor or combination of P2 receptors.
Yu
H
H
Medical Research Council Group in Periodontal Physiology, University of Toronto, Ontario, Canada.
Ferrier
J
J
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000502:physiology*; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D010010:Osteoclasts / Q000502:physiology*; D037342:Pertussis Toxin; D011817:Rabbits; D018048:Receptors, Purinergic P2 / Q000502:physiology; D015398:Signal Transduction; D013873:Thionucleotides / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D018048:Receptors, Purinergic P2; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; C023427:guanosine 5'-O-(2-thiodiphosphate); D000255:Adenosine Triphosphate; D037342:Pertussis Toxin; D008274:Magnesium; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002118:Calcium; D014544:Uridine Triphosphate; C008501:2-methylthio-ATP