A Matter of the Heart: The African Clawed Frog Xenopus as a Model for Studying Vertebrate Cardiogenesis and Congenital Heart Defects.

Annemarie Hempel,Michael Kühl

doi:10.3390/jcdd3020021

Annemarie Hempel, Michael Kühl

Open Access

https://doi.org/10.3390/jcdd3020021

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Abstract

The African clawed frog, Xenopus, is a valuable non-mammalian model organism to investigate vertebrate heart development and to explore the underlying molecular mechanisms of human congenital heart defects (CHDs). In this review, we outline the similarities between Xenopus and mammalian cardiogenesis, and provide an overview of well-studied cardiac genes in Xenopus, which have been associated with congenital heart conditions. Additionally, we highlight advantages of modeling candidate genes derived from genome wide association studies (GWAS) in Xenopus and discuss commonly used techniques.

Highlights

In the last decades, studies in amphibians such as the African clawed frog Xenopus laevis have substantially contributed to deciphering the mechanisms of early vertebrate heart development
We outline the similarities between Xenopus and mammalian cardiogenesis, and provide an overview of well-studied cardiac genes in Xenopus, which have been associated with congenital heart conditions
We highlight advantages of modeling candidate genes derived from genome wide association studies (GWAS) in Xenopus and discuss commonly used techniques

Summary

Advantages of Xenopus as a Model Organism

Studies in amphibians such as the African clawed frog Xenopus laevis have substantially contributed to deciphering the mechanisms of early vertebrate heart development. The extrauterine development of the embryos and detailed fate-maps [5,6,7] allow tissue-specific manipulations like microinjections or mechanistic analysis in explant assays. Early embryos are capable of developing to early tadpole stages in the absence of a working circulation system. This is advantageous because, unlike in mammalian models, it enables the study of early cardiovascular defects in vivo that are not complicated by secondary effects resulting from lack of circulation. Detailed gene expression maps of molecular cardiac markers for the specific cardiac lineages and the different stages of cardiogenesis are available [8] and enable researchers to monitor gene expression in functional studies by in situ hybridization. With respect to MO based strategies and novel genome editing approaches, it is noteworthy to mention that Xenopus laevis is tetraploid whereas the related Xenopus tropicalis is diploid

Tool Kit for Studying Heart Development and Diseases in Xenopus

Xenopus Models for Human Congenital Heart Defects

Findings

Modeling GWAS Candidates Associated with CHDs in Xenopus