Characterization of paralogous uncx transcription factor encoding genes in zebrafish

Abstract

The paired-type homeodomain transcription factor Uncx is involved in multiple processes of embryogenesis in vertebrates. Reasoning that zebrafish genes uncx4.1 and uncx are orthologs of mouse Uncx , we studied their genomic environment and developmental expression. Evolutionary analyses indicate the zebrafish uncx genes as being paralogs deriving from teleost-specific whole-genome duplication. Whole-mount in situ mRNA hybridization of uncx transcripts in zebrafish embryos reveals novel expression domains, confirms those previously known, and suggests sub-functionalization of paralogs. Using genetic mutants and pharmacological inhibitors, we investigate the role of signaling pathways on the expression of zebrafish uncx genes in developing somites. In identifying putative functional role(s) of zebrafish uncx genes, we hypothesized that they encode transcription factors that coordinate growth and innervation of somitic muscles. • The Uncx4.1 and Uncx genes derive from the teleost-specific whole-genome duplication. • Uncx genes are expressed during embryogenesis in unique and overlapping domains. • Uncx gene expression during somite differentiation is regulated by FGF signaling. • Synteny and expression profiles correlate Uncx genes with axon guidance.