Ca2+ mobilization and capacitative Ca2+ entry regulate DNA synthesis in cultured chick retinal neuroepithelial cells.
Release of Ca2+ from intracellular Ca2+ stores (Ca2+ mobilization) and capacitative Ca2+ entry have been shown to be inducible in neuroepithelial cells of the early embryonic chick retina. Both types of Ca2+ responses decline parallel with retinal progenitor cell proliferation. To investigate their potential role in the regulation of neuroepithelial cell proliferation, we studied the effects of 2,5-di-tert-butylhydroquinone (DBHQ), an inhibitor of the Ca2+ pump of intracellular Ca2+ stores, and of SK&F 96365, an inhibitor of capacitative Ca2+ entry, on DNA synthesis in retinal organ cultures from embryonic day 3 (E3) chicks and in dissociated cultures from E7 and E9 chick retinae. We demonstrate that both antagonists inhibit [3H]-thymidine incorporation in a dose-dependent manner without affecting cell viability or morphology. The inhibition of [3H]-thymidine incorporation by SK&F 96365 occurred in the same concentration range (IC50: approximately 4 microM) as the blockade of capacitative Ca2+ entry in the E3 retinal organ culture. At a concentration of 5 microM SK&F 96365. DNA synthesis was reduced by 71, 40 and 32% in the E3, E7 and E9 cultures, respectively. Application of DBHQ at concentrations which led to depletion of intracellular Ca2+ stores also inhibited [3H]-thymidine incorporation with IC50 values of 20-30 microM in the different cultures. Our results suggest the involvement of Ca2+ mobilization and capacitative Ca2+ entry in the regulation of DNA synthesis in the developing neural retina.
Sugioka
M
M
Institute of Anatomy I, University of Freiburg, Germany.
Zhou
W L
WL
Hofmann
H D
HD
Yamashita
M
M
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000187:drug effects*; D002478:Cells, Cultured; D002642:Chick Embryo; D004247:DNA / Q000096:biosynthesis*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects; D006873:Hydroquinones / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D009924:Organ Culture Techniques; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D006873:Hydroquinones; D007093:Imidazoles; D014316:Tritium; C019359:2,5-di-tert-butylhydroquinone; D004247:DNA; D000252:Calcium-Transporting ATPases; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D013936:Thymidine