CPEB dimerization ameliorates the deteriorating effect of CPEB overexpression. (A) Expression of exogenous CPEB WT, dimer CPEB-CPEB, and ΔZF mutant. Tubulin served as a loading control. (B) Exogenous CPEB (WT) slowed the rate of oocyte maturation while the CPEB dimer (C-C) had no effect. The maturation rate of dimer expression was significantly faster than that of WT expression (#). (C) Co-expression of luciferase with CPE-containing 3′ UTR shows that exogenous WT CPEB decreased its expression upon GVBD but not the dimeric CPEB. Luciferase expression with CPEB dimer (C-C) was significantly higher than that of CPEB WT (#), similar to noninjected oocytes (NI). On the right, various CPEB expressions did not affect luciferase expression with no CPE in its 3′ UTR (Luc-mt). NI-p, noninjected oocytes without progesterone treatment; NI, noninjected; WT, wild-type CPEB; C-C, tandem CPEB dimers; ΔZF, zinc finger deletion of CPEB. For the statistics, one mark represents P-value < 0.05; two marks represent P-value < 5 × 10−3; three marks represent P-value < 5 × 10−4 as determined by paired t-test.
