Characterization of spatial and temporal expression pattern of Col15a1b during zebrafish development.

In mammals, collagen XV is primarily expressed in skeletal and cardiac muscles, and loss of its expression in mice results in a mild skeletal myopathy. We recently identified Col15a1a, a zebrafish ortholog of the human collagen XV gene which expression was restricted to notochord in embryos. Col15a1a knockdown led to defects in muscle maintenance via Shh signaling. Here we report that zebrafish express a second ortholog Col15a1b. The identification of its complete primary sequence showed that the overall structure of collagen XV is well conserved between vertebrates. Whole mount in situ hybridization and RT-PCR analysis revealed that at 12hpf Col15a1b is mainly expressed in slow muscle cell lineage and in nervous tissues, and, at later stages transcripts are detected in eyes, otic placodes and aortic arches. Based on the expression pattern of col15a1b, sequence alignments and synteny comparisons, we conclude that, contrary to collagen XVa, the zebrafish collagen XVb likely displays the same or similar function than the mammalian orthologs.