1-Methyladenine production from ATP by starfish ovarian follicle cells.
1-Methyladenine (1-MeAde), the oocyte maturation-inducing substance in starfish, is produced by ovarian follicle cells upon stimulation with a gonad-stimulating substance (GSS) released from the radial nerves. We have shown previously that GSS causes a reduction in the intracellular levels of ATP coincident with 1-MeAde production. The present study examined whether the adenine molecule of 1-MeAde is directly derived from ATP. When isolated follicle cells from the starfish Asterina pectinifera were preloaded with [U-14C]adenine or [U-14C]adenosine, there was an increase in the intracellular levels of radiolabeled adenine nucleotides, particularly ATP. Following further incubation with GSS, the intracellular levels of radiolabeled ATP decreased, concomitant with a marked increase in the levels of [14C]1-MeAde in the medium. The amount of ATP consumed under the influence of GSS was similar to the amount of 1-MeAde produced. However, there was no change in the levels of ADP and AMP regardless of the presence or absence of GSS. These findings strongly suggest that 1-MeAde is synthesized from ATP as a substrate in follicle cells under the influence of GSS. Furthermore, using [methyl-3H]methionine, the methyl group of 1-MeAde was found to be derived from methionine. Thus GSS appears to stimulate the synthesis of 1-MeAde from ATP via the methylation process in starfish ovarian follicle cells.
Mita
M
M
Department of Biology, School of Education, Waseda University, Tokyo 169-8050, Japan.
Yoshikuni
M
M
Nagahama
Y
Y
D000225:Adenine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D005260:Female; D007447:Invertebrate Hormones / Q000494:pharmacology; D008745:Methylation; D006080:Ovarian Follicle / Q000187:drug effects / Q000378:metabolism; D013215:Starfish / Q000378:metabolism*; D014316:Tritium
D002250:Carbon Radioisotopes; D007447:Invertebrate Hormones; D014316:Tritium; D000249:Adenosine Monophosphate; C008407:1-methyladenine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000225:Adenine