ATP induces proliferation of retinal cells in culture via activation of PKC and extracellular signal-regulated kinase cascade.
Both ATP and acetylcholine can induce the mobilization of intracellular calcium in the early developing chick embryo retina, a response that decreases during retinal development. In this study, the effects of these transmitters on the turnover of phosphoinositides and proliferation of developing retinal cells in culture were characterized. While ATP, UTP or carbachol were able to induce a >400% accumulation of phosphoinositides in retinal cell cultures, only ATP promoted a dose-dependent increase in [(3)H]-thymidine incorporation in cultured cells (EC(50)=8.6 microM), a response that was inhibited by the P2 receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS) (0.1 or 0.25 mM). ADP, but not UTP or adenosine, also stimulated the proliferation of retinal cells (EC(50)=5.8 microM), indicating that activation of P2Y1 receptors mediates the proliferative response of retinal cells to ATP. The mitogenic effect of ATP was completely prevented by the PKC inhibitor chelerythrine chloride (0.5 microM) and the phospholipase C (PLC) inhibitor U73122 (0.5 microM). PD 98059 (25 or 50 microM), an inhibitor of the activation of extracellular signal-regulated kinases (ERKs) also blocked the increase in [(3)H]-thymidine incorporation induced by ATP. Moreover, the effect of ATP was pronounced in cultures obtained from retinas at embryonic days 6-8, but not at day 9. Since Müller and bipolar cells are the predominant cell types that proliferate at these embryonic stages, our data suggest that ATP, through activation of P2Y1 receptors coupled to phospholipase C, PKC and MAP kinases, affects DNA synthesis in one or both of these cell types in culture.
Sanches
Glauco
G
Departament of Neurobiology, Institute of Biology, Federal Fluminense University, Cx. Postal 100180, Niterói, RJ 24001-970, Brazil.
de Alencar
Laura Sá
LS
Ventura
Ana Lucia Marques
AL
D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002642:Chick Embryo; D004247:DNA / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism*; D023421:Models, Animal; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000187:drug effects / Q000378:metabolism*; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D058472:Receptors, Purinergic P2Y1; D012160:Retina / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism*; D014544:Uridine Triphosphate / Q000378:metabolism / Q000494:pharmacology
D004791:Enzyme Inhibitors; D010716:Phosphatidylinositols; D010975:Platelet Aggregation Inhibitors; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D002217:Carbachol; D004247:DNA; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D014544:Uridine Triphosphate; D013936:Thymidine