(R140) Proteomic and Transcriptomic Analysis of Neural Cell Fate in Developing Xenopus Embryos

Owen Ivan (University of Notre Dame)| Kyle Dubiak (University of Notre Dame)| Norman Dovichi (University of Notre Dame)| Paul Huber (University of Notre Dame)

The progeny of the D1 blastomere in the 8-cell X. laevis embryo make major contributions to the central nervous system, brain, and retina of the adult animal.  The lineage of this cell was tracked at the protein and mRNA levels at seven developmental time points up to the mid-neurula stage.  In addition, descendant cells from an excised D1 blastomere were analyzed at the same developmental stages.  Transcriptomic analysis reveals that at early neurulation, the progeny tissue has committed to the expected neural fate, whereas the explant tissue has begun to differentiate into non-neural ectoderm/epidermis.  Bioinformatics analysis indicates that Notch signaling through the Jagged 1 (Jag1), Jagged 2 (Jag2), and Delta-like 1 (Dll1) ligands is critical for determining the neural fate of the D1 progeny in the intact embryo.  This study has also revealed a considerable amount of regulation at the level of translation.  Notable examples include REST and Churchill.  While the mRNA encoding these proteins is found in D1 progeny of the intact embryo and the explant tissue, REST protein, a repressor of neural gene expression, was only detected in explant tissue.  Conversely, Churchill protein, involved in neural induction, was only detected in D1 progeny from the intact embryo.  Continued bioinformatics analysis of the data generated by the strategy used here has three specific aims: 1. Identification of other intercellular signaling pathways that determine the neural fate of D1 progeny; 2. Identification of novel gene products that direct neurogenesis; 3.  Identification of translational regulators (RNA binding proteins and miRNAs) of neural-specific transcripts.