Project description:Cardiac trabeculation is a highly regulated process that starts with the delamination of cardiomyocytes from the compact wall to form stereotypical muscular ridges in the developing ventricle. The Hippo signaling pathway has been implicated in cardiac development but many questions remain. We investigated the role of Wwtr1, a nuclear effector of the Hippo pathway, in zebrafish and find that its loss results in hearts with reduced trabeculation. However, in mosaic animals, wwtr1-/- cardiomyocytes contribute more frequently than wwtr1+/- cardiomyocytes to the trabecular layer of wild-type hearts. To investigate this paradox, we examined the myocardial wall at early stages and find that loss of Wwtr1 leads to disruption of the compact wall architecture, as evidenced by the disorganized cortical actin structure and abnormal cell-cell junctions. The mutant compact wall is not able to support trabeculation as, in mosaic animals, wild-type cardiomyocytes are more frequently in the compact layer of mutant than heterozygous hearts. Therefore, we propose that Wwtr1 establishes the compact wall architecture necessary for trabeculation and that it also modulates a cardiomyocyte’s decision to enter the trabecular layer.
Project description:All vertebrates have multiple genes encoding for different CASQ isoforms. Increasing interest has been focused on mammalian and human CASQ genes since mutations of both cardiac (CASQ2) and skeletal (CASQ1) isoforms cause different, and sometime severe, human pathologies Danio rerio (zebrafish) is a powerful model for studying function and mutations of human proteins. In this work expression, biochemical properties and cellular and sub-cellular localization of Danio rerio native CASQ isoforms are investigated. By quantitative PCR three mRNAs were detected in skeletal muscle and one mRNA in heart. Three zebrafish CASQs were identified by mass spectrometry and they share properties with mammalian skeletal and cardiac CASQs. Skeletal calsequestrins were found primarily, but not exclusively, at the sarcomere Z-line level where Terminal Cisternae of Sarcoplasmic reticulum are located.
Project description:Purpose: Construction of 3D zebrafish spatial transcriptomics data for studying the establishment of AP axis. Methods: We performed serial bulk RNA-seq data of zebrafish embryo at three development points. Using the published spatial transcriptomics data as references, we implemented Palette to infer spatial gene expression from bulk RNA-seq data and constructed 3D embryonic spatial transcriptomics. The constructed 3D transcriptomics data was then projected on zebrafish embryo images with 3D coordinates, establishing a spatial gene expression atlas named Danio rerio Asymmetrical Maps (DreAM). Results: DreAM provides a powerful platform for visualizing gene expression patterns on zebrafish morphology and investigating spatial cell-cell interactions. Conclusions: Our work used DreAM to explore the establishment of anteroposterior (AP) axis, and identified multiple morphogen gradients that played essential roles in determining cell AP positions. Finally, we difined a hox score, and comprehensively demonstrated the spatial collinearity of Hox genes at single-cell resolution during development.