Kunitomi Chisato, Romero Mayra, Daldello Enrico Maria, Schindler Karen, Conti Marco
Center for Reproductive Sciences, University of California, San Francisco, CA 94143, USA.
Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, CA 94143, USA.
bioRxiv. 2024 Jan 19:2024.01.17.575938. doi: 10.1101/2024.01.17.575938.
The RNA-binding protein cytoplasmic polyadenylation element binding 1 (CPEB1) plays a fundamental role in the regulation of mRNA translation in oocytes. However, the nature of protein kinase cascades modulating the activity of CPEB1 is still a matter of controversy. Using genetic and pharmacological tools and detailed time courses, here we have reevaluated the relationship between CPEB1 phosphorylation and the activation of translation during mouse oocyte maturation. We show that both the CDK1/MAPK and AURKA/PLK1 pathways converge on the phosphorylation of CPEB1 during prometaphase. Only inactivation of the CDK1/MAPK pathway disrupts translation, while inactivation of either pathway leads to CPEB1 stabilization. However, stabilization of CPEB1 induced by inactivation of the AURKA/PLK1 does not affect translation, indicating that destabilization/degradation can be dissociated from translational activation. The accumulation of the endogenous CCNB1 protein closely recapitulates the translation data. These findings support the overarching hypothesis that the activation of translation in prometaphase in mouse oocytes relies on a CDK1-dependent CPEB1 phosphorylation, and this translational activation precedes CPEB1 destabilization.
RNA 结合蛋白细胞质聚腺苷酸化元件结合蛋白 1（CPEB1）在卵母细胞 mRNA 翻译调控中发挥着重要作用。然而，调节 CPEB1 活性的蛋白激酶级联反应的本质仍存在争议。利用遗传和药理学工具以及详细的时间进程，我们在此重新评估了小鼠卵母细胞成熟过程中 CPEB1 磷酸化与翻译激活之间的关系。我们发现，在中期，CDK1/MAPK 和 AURKA/PLK1 两条途径都汇聚于 CPEB1 的磷酸化。只有 CDK1/MAPK 途径的失活会破坏翻译，而任何一条途径的失活都会导致 CPEB1 的稳定。然而，AURKA/PLK1 失活诱导的 CPEB1 稳定并不影响翻译，这表明去稳定化/降解与翻译激活可以分离。内源性 CCNB1 蛋白的积累与翻译数据密切相符。这些发现支持了一个总体假设，即小鼠卵母细胞中期的翻译激活依赖于 CDK1 依赖的 CPEB1 磷酸化，并且这种翻译激活先于 CPEB1 的去稳定化。
