Regenerative therapy for degenerative spine disorders requires the identification of cells that can slow down and possibly reverse degenerative processes. Here, we identify an unanticipated wound-specific notochord sheath cell subpopulation that expresses Wilms Tumor (WT) 1b following injury in zebrafish. We show that localized damage leads to Wt1b expression in sheath cells, and that wt1b+cells migrate into the wound to form a stopper-like structure, likely to maintain structural integrity. Wt1b+sheath cells are distinct in expressing cartilage and vacuolar genes, and in repressing a Wt1b-p53 transcriptional programme. At the wound, wt1b+and entpd5+ cells constitute separate, tightly-associated subpopulations. Surprisingly, wt1b expression at the site of injury is maintained even into adult stages in developing vertebrae, which form in an untypical manner via a cartilage intermediate. Given that notochord cells are retained in adult intervertebral discs, the identification of novel subpopulations may have important implications for regenerative spine disorder treatments.

Figure: In transgenic fish expressing GFP in the notochord vacuolated cells, GFP-expressing cells appeared 24-72 hours after injury.

The nature of host organs and genes that underlie tumor-induced physiological disruption on host has been poorly understood. Here, we establish a novel zebrafish intestinal tumor model, and find that hepatic cyp7a1, the rate-limiting factor for synthesizing bile acids (bile alcohol (BA) in zebrafish) is important for such a phenomenon. We created a transgenic zebrafish line, in which an oncogenic form of kras (krasG12D) was expressed in the posterior intestine by the Gal4-UAS method, and found that the intestinal tumor was formed. The intestinal tumor then caused detrimental effects on host, including liver inflammation, hepatomegaly, growth defects, and organismal death. Whole-organismal level gene expression analysis and metabolite measurements revealed that the intestinal tumor reduced total BA levels possibly via altered expression of hepatic cyp7a1. We demonstrated overexpression of cyp7a1 in the liver restored the BA synthesis and ameliorated tumor-induced liver inflammation. Thus, we discovered a previously unknown role of cyp7a1 as the host gene that links the intestinal tumor to the hepatic cholesterol-BA metabolism and liver inflammation. Our model provides an important basis to investigate host genes responsible for tumor-induced phenotypes and to uncover mechanisms underlying how tumors adversely affect host organisms.

Figure: A transgenic zebrafish model bearing the intestine tumor created by the Gal4-UAS method. A, B; control. C, D: transgenic fish. B, D: fluorescent images. Dotted lines indicate the shape and size of the intestine. An arrow indicates EGFP expression.

A major challenge in analyzing the data from high-throughput next-generation sequencing (NGS) is how to handle the huge amounts of data and variety of NGS tools and visualize the resultant outputs. To address these issues, we developed a cloud-based data analysis platform, Maser (Management and Analysis System for Enormous Reads), and an original genome browser, Genome Explorer (GE).

Maser realized a more user-friendly analysis platform especially for beginners by improving graphical display and providing the selected standard pipelines that work with built-in genome browser. All the analyses executed on Maser are recorded in the analysis history, helping users to trace and repeat the analyses. The entire process of analysis and its histories can be shared with collaborators or opened to the public. In conclusion, our system is useful for managing, analyzing, and visualizing NGS data and achieves traceability, reproducibility, and transparency of NGS analysis.

Maser is currently supported by Japan Agency for Medical Research and Development (AMED).

Figure 1: Maser tutorial and user registration page

Figure 2: Maser’s Top Page (Only registered user can access)

Pressrelease (In Japanese only)

Under stress conditions, the coactivator Multiprotein-bridging factor 1 (Mbf1) translocates from the cytoplasm into the nucleus to induce stress-response genes. However, its role in the cytoplasm, where it is mainly located, has remained elusive. Here, we show that Drosophila Mbf1 associates with E(z) mRNA and protects it from degradation by the exoribonuclease Pacman, thereby ensuring Polycomb silencing. This mechanism would also allow flexibility in Polycomb silencing, as Mbf1 protein expression declines upon differentiation.

In addition to E(z) mRNA, Mbf1 binds to mRNAs of various stress-response genes. Therefore, Mbf1 appears to contribute to various types of stress defense as both a nuclear coactivator and as a cytoplasmic mRNA-stabilizing protein. It is intriguing that Mbf1 contributes to the same biological function through different subcellular localisation.

Mbf1 binds to E(z) mRNA and protects it from degradation by Pacman. Polycomb silencing represses expression of the pacman gene. Therefore, Mbf1 ensures robust Polycomb silencing.