Two distinct P2 purinergic receptors, P2Y and P2U, are coupled to phospholipase C in mouse pineal gland tumor cells.
We found that extracellular ATP can increase the intracellular Ca2+ concentration ([Ca2+]i) in mouse pineal gland tumor (PGT-beta) cells. Studies of the [Ca2+]i rise using nucleotides and ATP analogues established the following potency order: ATP, adenosine 5'-O-(3-thiotriphosphate) > or = UTP > 2-chloro-ATP > 3'-O-(4-benzoyl)benzoyl ATP, GTP > or = 2-methylthio ATP, adenosine 5'-O-(2-thiodiphosphate) (ADP beta S) > CTP. AMP, adenosine, alpha,beta-methyleneadenosine 5'-triphosphate, beta,gamma-methyleneadenosine 5'-triphosphate, and UMP had little or no effect on the [Ca2+]i rise. Raising the extracellular Mg2+ concentration to 10 mM decreases the ATP- and UTP-induced [Ca2+]i rise, because the responses depend on the ATP4- and UTP4- concentrations, respectively. The P2U purinoceptor-selective agonist UTP and the P2Y purinoceptor-selective agonist ADP beta S induce inositol 1,4,5-trisphosphate generation in a concentration-dependent manner with maximal effective concentrations of approximately 100 microM. In sequential stimulation, UTP and ADP beta S do not interfere with each other in raising the [Ca2+]i. Costimulation with UTP and ADP beta S results in additive inositol 1,4,5-trisphosphate generation to a similar extent as is achieved with ATP alone. Pretreatment with pertussis toxin inhibits the action of UTP and ATP by maximally 45-55%, whereas it has no effect on the ADP beta S response. Treatment with 1 microM phorbol 12-myristate 13-acetate inhibits the ADP beta S-induced [Ca2+]i rise more effectively than the ATP- and UTP-induced responses. These results suggest that P2U and P2Y purinoceptors coexist on PGT-beta cells and that both receptors are linked to phospholipase C.
Suh
B C
BC
Department of Life Science, Pohang University of Science and Technology, Republic of Korea.
Son
J H
JH
Joh
T H
TH
Kim
K T
KT
D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D015415:Biomarkers; D002118:Calcium / Q000378:metabolism; D002273:Carcinogens / Q000494:pharmacology; D002461:Cell Line, Transformed / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D004305:Dose-Response Relationship, Drug; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D037342:Pertussis Toxin; D010870:Pineal Gland / Q000737:chemistry / Q000166:cytology*; D018048:Receptors, Purinergic P2 / Q000737:chemistry / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014365:Tryptophan Hydroxylase / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism*; D014544:Uridine Triphosphate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000952:Antigens, Polyomavirus Transforming; D015415:Biomarkers; D002273:Carcinogens; D018048:Receptors, Purinergic P2; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; C030812:adenosine 5'-O-(2-thiodiphosphate); D000244:Adenosine Diphosphate; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D014365:Tryptophan Hydroxylase; D001191:Arylamine N-Acetyltransferase; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D008274:Magnesium; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D014544:Uridine Triphosphate