Introduction: Emery-Dreifuss muscular dystrophy (EDMD) is a rare and heterogeneous disorder characterized by early-onset joint contractures, progressive muscle weakness and wasting, and cardiac defects. Most reported cases of EDMD result from mutations in one of the following nuclear envelope proteins encoding genes: LMNA, EMD, SYNE1, SYNE2, and TMEM43. These proteins provide structural support to the nucleus and are essential for gene expression regulation and chromatin organization. Interestingly, EDMD can also arise from mutations in the FHL1 gene, which is not a nuclear envelope protein but is highly expressed in skeletal and cardiac muscles. The molecular mechanisms underlying EDMD remain poorly understood, as the genes implicated are ubiquitously expressed, yet the disorder manifests in a highly tissue-specific manner. In this study, we aim to investigate the molecular basis of EDMD using the zebrafish models of this disorder.
Methods: The zebrafish models of EDMD were generated following the knockout of lmna, emd, fhl1a, and fhl1b using the CRISPR-Cas9 system. To investigate the localizations and interactions of EDMD-related proteins using live imaging, we fused Emerin and Lamin A/C with fluorescent proteins and created transgenic lines.
Results: The knockouts of the emd, lmna, fhl1a, and fhl1b genes have been confirmed by Sanger sequencing. In embryos derived from F2 generation mutant lines, we have found a low frequency of abnormal phenotypes. Using transgenic lines, we show the expression and localization of Lamin and Emerin at 24 hours post-fertilization (hpf) and 7 days post-fertilization (dpf).
Conclusion: We have generated knockout and transgenic lines for genes associated with EDMD. In the subsequent phases of our research, we will use multi-omics, live imaging, and histological studies to examine the various characteristics of zebrafish models of this disorder.