Proteomic-based Identification Of Maternal Proteins In Mature Mouse Oocytes

Mammalian oocyte is marked by extraordinary biological competence. It can reprogram zygotic genome, initiate and support early embryonic development as well as transmit the maternal genetic information to the offspring. More and more evidence has shown that maternal proteins stored in oocytes have critical roles in fertilization, chromatin remodeling, zygotic genome activation, embryo compaction and other processes. Therefore, identification and investigation of maternal proteins will be of great significance to the understanding of mammalian embryonic development. In this study, we applied a more efficient and comprehensive strategy to investigate the maternal proteins in oocytes.First of all, we employed one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (1D SDS-PAGE) and reverse-phase liquid chromatography tandem mass spectrometry (RP-LC-MS/MS)to construct the protein profile of mouse metaphase II oocytes. 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. We then submit the protein profile to the the Proteomics identifications database (PRIDE). Click the link of each maternal protein, we can see the detailed identification information, including identified peptides and corresponding spectra. The construction of this public database will provide valuable resource for the study of maternal proteins and early embryonic development. Secondly, detailed bioinformatic analysis helps us screen a group of proteins, which may play key roles in early embryonic development. These proteins will be good candidates for further screening for maternal effect proteins.Mouse Mâ…¡oocytes can be parthenogenetically activated by strontium chloride and then develop to blastocyst. In order to search for players in this process, we employed classical methods of quantitative proteomics 2D-PAGE + MALDI-TOF/TOF to compare the protein profiles of oocytes before and after parthenogenetic activation. Totally, 78 protein spots were successfully identified, corresponding to 52 different proteins. Bioinformatics analysis has revealed that many proteins are involved in cell proliferation and embryonic development, and some proteins have been shown to be involved in chromatin remodeling. Therefore, this protein list provides candidate molecules for the research on oocyte activation and early embryonic development.Following the construction of the protein profile of oocytes, we selected a number of maternal proteins for further research. Annexin VII showed a granular distribution under the plasma membrane, opposite the chromosomes. The specific distribution pattern implied that Annexinâ…¦might trigger calcium oscillation during fertilization. In addition, the expression and localization of ECAT1, OOEP, RBPMS2, TLE6, and ZBED3 in mouse ovaries and early embryos were also investigated. In this study, two complementary strategies were employed to construct the protein profile of mouse Mâ…¡oocytes and this profile provided comprehensive knowledge of maternal proteins existed in mouse oocyte, laid a good foundation for further research of maternal proteins and early embryonic development.