Proteomic-based identification of maternal proteins in mature mouse oocytes

Ping Zhang,Zuomin Zhou,Xiaojian Ni,Ying Guo,Ran Huo,Yufeng Wang,Jiahao Sha,Xuejiang Guo

doi:10.1186/1471-2164-10-348

Abstract

BackgroundThe mature mouse oocyte contains the full complement of maternal proteins required for fertilization, reprogramming, zygotic gene activation (ZGA), and the early stages of embryogenesis. However, due to limitations of traditional proteomics strategies, only a few abundantly expressed proteins have yet been identified. Our laboratory applied a more effective strategy: one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (1D SDS-PAGE) and reverse-phase liquid chromatography tandem mass spectrometry (RP-LC-MS/MS) were employed to analyze the mature oocyte proteome in depth.ResultsUsing this high-performance proteomic approach, we successfully identified 625 different proteins from 2700 mature mouse oocytes lacking zona pellucidae. This is the largest catalog of mature mouse oocyte proteins compiled to date. According to their pattern of expression, we screened 76 maternal proteins with high levels of mRNA expression both in oocytes and fertilized eggs. Many well-known maternal effect proteins were included in this subset, including MATER and NPM2. In addition, our mouse oocyte proteome was compared with a recently published mouse embryonic stem cell (ESC) proteome and 371 overlapping proteins were identified.ConclusionThis proteomics analysis will be a valuable resource to aid in the characterization of important maternal proteins involved in oogenesis, fertilization, early embryonic development and in revealing their mechanisms of action.

Highlights

The mature mouse oocyte contains the full complement of maternal proteins required for fertilization, reprogramming, zygotic gene activation (ZGA), and the early stages of embryogenesis
2700 zona pellucida (ZP)-free metaphase II (MII) oocytes were collected and the integrity of the oocytes was checked rigorously according to the criteria outlined in the Materials and Methods to ensure only morphologically normal oocytes were chosen for further research (Figure 1)
The gel was cut into 29 slices, proteins were in-gel digested with trypsin, and the resulting peptides extracted from each gel slice were analyzed by automated reverse phase LC (RP-LC) coupled with mass spectrometry (MS)/ MS

Summary

Introduction

The mature mouse oocyte contains the full complement of maternal proteins required for fertilization, reprogramming, zygotic gene activation (ZGA), and the early stages of embryogenesis. Mammalian reproduction is a complicated physiological process involving many important events, such as generation of mature gametes, fertilization, zygotic gene activation (ZGA), and embryonic development. Many maternal proteins stored in oocytes play significant roles in later stages, namely fertilization and early embryogenesis. Several maternal-effect genes/proteins have recently been identified in mammals, and their importance in embryonic development has been demonstrated. MATER (Maternal antigen that embryos require; official name Nlrp5) is one of the first characterized maternal effect proteins in mice, the absence of which precludes embryonic progression beyond the 2-cell stage [7]. The identification and molecular characterization of novel maternal proteins will be of great significance and novel proteomic technologies can potentially deduce most of the maternal proteins in mature oocytes

Methods

Results

Discussion

Conclusion