Use of zebrafish models to investigate rare human disease

Abstract

Rare diseases are collectively common and often extremely debilitating. Following the emergence of next-generation sequencing (NGS) technologies, the variants underpinning rare genetic disorders are being unearthed at an accelerating rate. However, many rare conditions lack effective treatments due to their poorly understood pathophysiology. There is therefore a growing demand for the development of novel experimental models of rare genetic diseases, so that potentially causative variants can be validated, pathogenic mechanisms can be investigated and therapeutic targets can be identified. Animal models of rare diseases need to be genetically and physiologically similar to humans, and well-suited to large-scale experimental manipulation, considering the vast number of novel variants that are being identified through NGS. The zebrafish has emerged as a popular model system for investigating these variants, combining conserved vertebrate characteristics with a capacity for large-scale phenotypic and therapeutic screening. In this review, we aim to highlight the unique advantages of the zebrafish over other in vivo model systems for the large-scale study of rare genetic variants. We will also consider the generation of zebrafish disease models from a practical standpoint, by discussing how genome editing technologies, particularly the recently developed clustered regularly interspaced repeat (CRISPR)/CRISPR-associated protein 9 system, can be used to model rare pathogenic variants in zebrafish. Finally, we will review examples in the literature where zebrafish models have played a pivotal role in confirming variant causality and revealing the underlying mechanisms of rare diseases, often with wider implications for our understanding of human biology.

Zebrafish mab21l2 mutants possess severe defects in optic cup morphogenesis, lens and cornea development

“…Defects in any of these processes during development can lead to severe congenital ocular disorders, and animal model systems have been critical in providing mechanistic insight into the nature of these disorders . Amongst these models, zebrafish have emerged as a highly useful system given the ability to perform forward and reverse genetic screens to generate disease alleles, and combine these with state of the art molecular, behavioral and imaging assays . While numerous specification and tissue segregation events precede overt eye development in zebrafish, the prospective optic cup emerges from the diencephalon at approximately the 5 somite stage (SS), and eye development proceeds rapidly thereafter.…”

“…12,13 Amongst these models, zebrafish have emerged as a highly useful system given the ability to perform forward and reverse genetic screens to generate disease alleles, and combine these with state of the art molecular, behavioral and imaging assays. 14,15 While numerous specification and tissue segregation events precede overt eye development in zebrafish, the prospective optic cup emerges from the diencephalon at approximately the 5 somite stage (SS), and eye development proceeds rapidly thereafter. Lens development begins at approximately the 16-18SS, when cells of the surface ectoderm begin to columnarize, divide, and thicken to form the lens placode.…”

Identification of Zebrafish Calcium Toolkit Genes and their Expression in the Brain

“…70% of human genes have at least one zebrafish orthologue) makes zebrafish an outstanding model for examining the molecular mechanisms of human diseases [73], assaying gene activity, and discovering novel compounds for the treatment of disease. CRISPR/Cas9 technology is well-established for zebrafish, and crispants can be created to introduce mutations of specific genes [30]. This creates the possibility of generating fish models of human diseases.…”

“…Zebrafish ( Danio rerio ) has been used extensively to study brain development, activity, and function and has emerged as a prominent model of disease states [30,31]. Zebrafish are a powerful model for investigating Ca 2+ -related processes in vivo because of their transparent larvae and ability to express Ca 2+ probes that can be targeted to various cellular organelles [32].…”

Visualisation of cholesterol and ganglioside GM1 in zebrafish models of Niemann–Pick type C disease and Smith–Lemli–Opitz syndrome using light sheet microscopy

“…Zebrafish lay eggs that are fertilised externally and at predictable times of day; they are also particularly amenable to genetic manipulation, e.g. by morpholino, CRISPR-Cas9 and TALENs (Adamson et al 2018 ). Zebrafish share a high degree of genetic similarity to humans, with zebrafish homologues for 71% of human genes (Howe et al 2013 ).…”