Aurora kinase A is not involved in CPEB1 phosphorylation and cyclin B1 mRNA polyadenylation during meiotic maturation of porcine oocytes.

Pavla Komrskova,Jaroslava Supolikova,Lucie Liskova,Michal Kubelka,Radek Malik,Barbora Prochazkova,Stepan Hladky,Andrej Susor,Claude Prigent

doi:10.1371/journal.pone.0101222

Abstract

Regulation of mRNA translation by cytoplasmic polyadenylation is known to be important for oocyte maturation and further development. This process is generally controlled by phosphorylation of cytoplasmic polyadenylation element binding protein 1 (CPEB1). The aim of this study is to determine the role of Aurora kinase A in CPEB1 phosphorylation and the consequent CPEB1-dependent polyadenylation of maternal mRNAs during mammalian oocyte meiosis. For this purpose, we specifically inhibited Aurora kinase A with MLN8237 during meiotic maturation of porcine oocytes. Using poly(A)-test PCR method, we monitored the effect of Aurora kinase A inhibition on poly(A)-tail extension of long and short cyclin B1 encoding mRNAs as markers of CPEB1-dependent cytoplasmic polyadenylation. Our results show that inhibition of Aurora kinase A activity impairs neither cyclin B1 mRNA polyadenylation nor its translation and that Aurora kinase A is unlikely to be involved in CPEB1 activating phosphorylation.

Highlights

Cytoplasmic polyadenylation is a well-documented regulatory mechanism, which governs the translation of maternal mRNAs in the oocytes of different species
Porcine cyclin B1 mRNA polyadenylation is independent of cytoplasmic polyadenylation element (CPE)-binding protein 1 (CPEB1) degradation In Xenopus oocytes, the cyclin B1 mRNA polyadenylation occurs at metaphase I and depends on the partial degradation of CPEB1 [7]
We examined the relationship between CPEB1 activation and degradation, Aurora kinase A (AURKA) activity and the cyclin B1 mRNA cytoplasmic polyadenylation and expression

Summary

Introduction

Cytoplasmic polyadenylation is a well-documented regulatory mechanism, which governs the translation of maternal mRNAs in the oocytes of different species. This enables the time- and spacespecific translation of the most important signaling molecules for the meiotic cell cycle, e.g. cyclins and c-mos [1]. The non-phosphorylated CPEB1 represses the translation initiation of CPE-containing mRNAs by recruiting other trans-acting factors such as Maskin and Pumilio [3,4,5]. The CPEB1 phosphorylation at Ser174 (in Xenopus oocytes, analogous to Thr172 in porcine oocytes) activates the polyadenylation of a CPE-containing mRNA by excluding the poly(A)-specific ribonuclease (PARN) from its 39UTR [6]. The partial degradation of CPEB1 is thought to be necessary for the cytoplasmic polyadenylation of mRNAs, which contain two or more CPEs in their 39UTR [7,12]

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