Comparative proteome analysis of the embryo proper and yolk sac membrane of day 11.5 cultured rat embryos

BACKGROUND: Proteomic analysis of cultured postimplantation rat embryos is expected to be useful for investigation into embryonic development. Here we analyzed protein expression in cultured postimplantation rat embryos by two-dimensional electrophoresis (2-DE) and mass-spectrometric protein identification. METHODS: Rat embryos were cultured from day 9.5 for 48 h or from day 10.5 for 24 h. Proteins of the embryo proper and yolk sac membrane were isolated by 2-DE and differentially analyzed with a 2-D analysis software. Selected protein spots in the 2-DE gels were identified by matrix-assisted laser desorption/ionization-time of flight tandem mass spectrometric analysis and protein database search. RESULTS: About 800 and 1,000 protein spots were matched through the replicate 2-DE gels each from one embryo in the embryo proper and yolk sac membrane, respectively, and virtually the same protein spots were observed irrespective to the length of culture period. From protein spots specific to the embryo proper (126 spots) and yolk sac membrane (304 spots), proteins involved in tissue-characteristic functions, such as morphogenesis and nutritional transfer, were identified: calponin, cellular retinoic acid binding protein, cofilin, myosin, and stathmin in the embryo proper, and Ash-m, dimerization cofactor of hepatocyte nuclear factor, ERM-binding phosphoprotein, cathepsin, and legumain in the yolk sac membrane. CONCLUSION: Proteomic analysis of cultured postimplantation rat embryos will be a new approach in developmental biology and toxicology at the protein level. Birth Defects Res (Part B), 2007. © 2007 Wiley-Liss, Inc.