Novel cross-regulation interactions between dlx genes in larval zebrafish

• Published in: Gene 2021-10, Vol.801, p.145848-145848, Article 145848
• Main Authors: Yu, Emily P.Y., Perin, Sofia, Saxena, Vishal, Ekker, Marc
• Format: Article
• Language: English
• Subjects: CRISPR-Cas9; Gene networks; Gene regulation; Whole mount in situ hybridization
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/j.gene.2021.145848

•Previous work assumed cross-regulation of dlx genes that are conserved in vertebrates.•To explore assumptions, dlx genes were knocked out in zebrafish using CRISPR-Cas9.•Cross-regulation of dlx genes was observed but more nuanced than previously expected.•Alternative pathways may exist to maintain dlx expression during early development. The homeodomain-containing transcription factors dlx1a, dlx2a, dlx5a and dlx6a are expressed in the zebrafish brain in overlapping patterns and are important in vertebrate development. Previous work in mice have suggested the overlapping expression pattern is in part due to cross-regulatory interactions among the aforementioned dlx genes. However, the extent of these interactions and whether they are conserved among vertebrates remains to be determined. Through whole-mount in situ hybridization in zebrafish dlx mutants produced by CRISPR-Cas9 mutagenesis, cross-regulatory interactions between dlx1a, dlx2a, dlx5a and dlx6a were examined from 24 to 72 h post fertilization (hpf). Notably, and different from previous work done in mouse, zebrafish dlx2a−/− mutants continue to express dlx5a until 72hpf, whereas deletion of both enhancers within the dlx5a/dlx6a locus resulted in delayed dlx5a/dlx6a expression and relative increased dlx2a expression. These results suggest alternative regulatory elements and pathways exist to mediate dlx expression in zebrafish and may highlight evolutionary differences in gene interactions between vertebrates.