Ciona robusta as model system for Intestinal Stem Cells Biology (CrISCs).

The mammalian adult intestinal stem cells (ISC) maintain gut homeostasis and generate all the different intestinal cells types, either during physiological renewal as well as in response to insults. We propose a comparative and evolutionary approach to better define the origin and the fundamental characteristics of the ISCs focusing on a non-vertebrate deuterostome, the protochordate Ciona robusta. This tunicate possesses a fully sequenced, high quality chromosome-scale genome and has striking analogies to the human and murine gut, which make this species as a suitable model to a comparative study. RNA-seq analysis on Stomach, Proximal and Distal Intestine has been performed to look at the genes expressed in the gastrointestinal tract. The availability of additional gene expression public datasets will allow to further refining the set of Stomach, Proximal and Distal Intestine markers, organizing them in networks of co-regulated genes, whose putative function will be investigated in detail by functional enrichment analyses. Their placement in signaling networks described in other organisms will be investigated through comparative transcriptomic analyses, which will take into account previously published datasets for other target species. Comparative histology and immunohistochemistry will corroborate the gene expression data, allowing the characterization of the Ciona intestinal cell type and the expression district of proliferative markers. A better understanding via cross-comparison of the mechanisms inducing the emergence of ISCs is a prerequisite for a comprehensive view of how these mechanisms subtend self-renewal and cell proliferation /differentiation and tissue homeostasis.