Investigating Inter- and Intra-Cellular Proteome Heterogeneity in the Xenopus Laevis Embryo

Abstract

Understanding embryonic development has broad implications, ranging from treating congenital defects to growing organs in vitro. During embryogenesis, temporal and spatial variation in the proteome is critical for regulating developmental processes. Typically, it is assumed that differences in protein abundance result primarily from differential protein expression in distinct cell types. However, it is also possible that asymmetric protein distribution throughout the embryo contributes to the formation of unique cellular proteomes. While this mechanism is widely accepted in fly embryos, its existence in vertebrates remains unclear. Previous proteomic analyses in the Wühr lab have been performed on whole embryos at various stages, combining measurements from all cells. Here, I investigated intracellular and intercellular proteome heterogeneity in developing Xenopus laevis embryos from the one-cell (NF 1) to eight-cell stage (NF 4). My colleague, Argit Marishta, measured intracellular protein distribution along the animal-vegetal (top-bottom) axis in unfertilized eggs. I developed a single-blastomere proteomics method to quantify relative protein abundance distributions up to the eight-cell stage. Interestingly, significant animal-vegetal asymmetry was observed at eight-cell stage, correlating with the intracellular protein distribution present in the unfertilized egg. This finding suggests that cellular differentiation during vertebrate development may partially result from asymmetric maternal protein distribution, rather than exclusively from cell-specific transcription, translation, or protein degradation.