Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Nexilin (NEXN) plays a crucial role in stabilizing the sarcomeric Z-disk of striated muscle fibers and, when mutated, leads to dilated cardiomyopathy in humans. Due to its early neonatal lethality in mice, the detailed impact of the constitutive homozygous <jats:italic>NEXN</jats:italic> knockout on heart and skeletal muscle morphology and function is insufficiently investigated. Here, we characterized a constitutive homozygous CRISPR/Cas9-mediated <jats:italic>nexn</jats:italic> knockout zebrafish model. We found that Nexn deficient embryos developed significantly reduced cardiac contractility and under stressed conditions also impaired skeletal muscle organization whereas skeletal muscle function seemed not to be affected. Remarkably, in contrast to <jats:italic>nexn</jats:italic> morphants, CRISPR/Cas9 <jats:italic>nexn</jats:italic><jats:sup><jats:italic>−/−</jats:italic></jats:sup> knockout embryos showed a milder phenotype without the development of a pronounced pericardial edema or blood congestion. <jats:italic>nexn</jats:italic>-specific expression analysis as well as whole transcriptome profiling suggest some degree of compensatory mechanisms. Transcripts of numerous essential sarcomeric proteins were massively induced and may mediate a sarcomere stabilizing function in <jats:italic>nexn</jats:italic><jats:sup><jats:italic>−/−</jats:italic></jats:sup> knockout embryos. Our findings demonstrate the successful generation and characterization of a constitutive homozygous <jats:italic>nexn</jats:italic> knockout line enabling the detailed investigation of the role of <jats:italic>nexn</jats:italic> on heart and skeletal muscle development and function as well as to assess putative compensatory mechanisms induced by the loss of Nexn.</jats:p>