Project description:The notochord is the eponymous feature of the chordates and an essential organ in chordate development. The notochord of the invertebrate chordate Ciona consists of only 40 cells, and is a longstanding model for studying differentiation and morphogenesis in a small, simple embryo. Here we perform RNAseq analysis on flow-sorted notochord cells from multiple stages of development to define a comprehensive Ciona notochord transcriptome. We identify 1364 genes with enriched expression in the notochord and extensively validate the results by in situ hybridization. This notochord gene set is highly enriched for Gene Ontology codes related to the extracellular matrix, cell adhesion and cytoskeleton, and contains numerous genes with intriguing potential functions in morphogenesis. Orthologs of 112 of the Ciona notochord genes have known notochord expression in vertebrates, more than twice as many as would be predicted by chance alone. This set of putative effector genes with notochord expression conserved from tunicates to vertebrates will be invaluable for testing hypotheses about the evolution of the notochord.
Project description:XBP transcription factors are well-known regulators of the the unfolded protein response and are required for plasma cell differentiation. However, recent studies have shown that the XBP1 gene is also expressed in the developing notochord of Ciona and various vertebrates, and to date its role in the formation of this organ is largely uncharacterized. We identified putative targets of Ci-XBP1 through a microarray screen, using RNAs extracted from embryos expressing mutant forms of this transcriptional regulator in the notochord. We expressed in the Ciona notochord a dominant-negative version of Ci-XBP1 (XBP DBD::GFP) by cloning its DNA-binding domain (DBD) downstream of the Ci-Brachyury (Ci-Bra) promoter. We created a constitutive activator form of Ci-XBP by fusing its DBD to the VP16 transactivation domain (Bra>XBP DBD::VP16::GFP). These constructs were introduced into 1-cell stage embryos and grown to the initial tailbud (iTb) stage to identify Ci-XBP notochord target genes.
Project description:Lumen formation and inflation are crucial for tubular organ morphogenesis, yet the underling mechanism remains largely unrevealed. Here, we applied 4D proteomics to screen the lumenogenesis-related proteins and reveal the potentially biological pathways that are involved in lumen inflation during notochord lumen formation in ascidian Ciona savignyi.
Project description:Expression profiling of Ciona intestinalis neurula and mid-tailbud stage embryos expressing altered forms of the transcription factor Ci-Tbx2/3 in the notochord
