Identification and characterization of the changed and stable transcripts during mouse oocyte maturation

There is massive destruction of transcripts during maturation of mouse oocytes. The objective of this project was to identify and characterize the transcripts that are degraded versus those that are stable during the transcriptionally silent germinal vesicle (GV)-stage to metaphase II (MII)-stage transition using the microarray approach. A system for oocyte transcript amplification using both internal and 3’-poly(A) priming was utilized to minimize the impact of complex variations in transcript polyadenylation prevalent during this transition. Transcripts were identified and quantified using Affymetrix Mouse Genome 430 v2.0 GeneChip. The significantly changed and stable transcripts were analyzed using Ingenuity Pathways Analysis and GenMAPP/MAPPFinder to characterize the biological themes underlying global changes in oocyte transcripts during maturation. It was concluded that the destruction of transcripts during the GV to MII transition is a selective rather than promiscuous process in mouse oocytes. In general, transcripts involved in processes that are associated with meiotic arrest at the GV-stage and the progression of oocyte maturation, such as oxidative phosphorylation, energy production, and protein synthesis and metabolism, were dramatically degraded. In contrast, transcripts encoding participants in signaling pathways essential for maintaining the unique characteristics of the MII-arrested oocyte, such as those involved in protein kinase pathways, were the most prominent among those stables. Keywords: Developmental stage (mature vs. immature) comparison Comparison immature GV-stage oocyte (3 biological replicates) with mature MII-stage oocytes (3 biological replicates)

小鼠卵母细胞成熟过程中存在大量转录本降解现象。本研究旨在利用基因微阵列技术，鉴定并表征转录沉默的生发泡（germinal vesicle, GV）期向第二次减数分裂中期（metaphase II, MII）期转变过程中，发生降解与保持稳定的两类转录本。本研究采用同时结合内部引物与3’端多聚腺苷酸（poly(A)）引物的卵母细胞转录本扩增体系，以最小化该转变过程中普遍存在的转录本多聚腺苷酸化复杂变异所带来的实验影响。使用Affymetrix小鼠基因组430 v2.0基因芯片对转录本进行鉴定与定量。采用Ingenuity通路分析（Ingenuity Pathways Analysis）与GenMAPP/MAPPFinder对显著差异表达及稳定的转录本进行分析，以阐明小鼠卵母细胞成熟过程中转录本整体变化背后的生物学主题。研究结果表明，小鼠卵母细胞GV期向MII期转变过程中的转录本降解是具有选择性的过程，而非无差别的随机降解。总体而言，与GV期减数分裂阻滞及卵母细胞成熟进程相关的转录本，如参与氧化磷酸化、能量产生以及蛋白质合成与代谢的转录本，发生了显著降解。相反，编码参与维持MII期阻滞卵母细胞独特特性所必需的信号通路（如蛋白激酶通路相关分子）的转录本，是稳定转录本中占比最高的类别。关键词：发育阶段（成熟vs未成熟）对比；未成熟GV期卵母细胞（3次生物学重复）与成熟MII期卵母细胞（3次生物学重复）的组间对照实验