Affiliation: | a Biosignal Research Center, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Showa-machi, 3-39-15, Maebashi 371-8512, Japan b Laboratory of Signal Transduction, Institute for Molecular and Cellular Regulation (IMCR), Gunma University, Maebashi 371-8512, Japan c Department of Basic Sciences for Medicine, Gunma University School of Health Sciences, Maebashi 371-8514, Japan d Department of Biology, Osaka University, Toyonaka, Osaka 560-0043, Japan |
Abstract: | Differentiation-inducing factor-1 (DIF-1; 1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)hexan-1-one) is a putative morphogen that induces stalk-cell formation in the cellular slime mold Dictyostelium discoideum. DIF-1 has previously been shown to suppress cell growth in mammalian cells. In this study, we examined the effects of DIF-1 on the progesterone-induced germinal vesicle breakdown in Xenopus laevis, which is thought to be mediated by a decrease in intracellular cAMP and the subsequent activation of mitogen-activated protein kinase (MAPK) and maturation-promoting factor, a complex of cdc2 and cyclin B, which regulates germinal vesicle breakdown. DIF-1 at 10–40 μM inhibited progesterone-induced germinal vesicle breakdown in de-folliculated oocytes in a dose-dependent manner. Progesterone-induced cdc2 activation, MAPK activation, and c-Mos accumulation were inhibited by DIF-1. Furthermore, DIF-1 was found to inhibit the progesterone-induced cAMP decrease in the oocytes. These results indicate that DIF-1 inhibits progesterone-induced germinal vesicle breakdown possibly by blocking the progesterone-induced decrease in [cAMP]i and the subsequent events in Xenopus oocytes. |