Regenerating zebrafish scales express a subset of genes involved in human skeletal disease

Scales are mineralised exoskeletal structures. When removed, an ontogenetic scale is quickly replaced following differentiation of the scale pocket-lining cells that regenerate a scale. Processes promoting de novo matrix formation and mineralisation initiated during scale regeneration are poorly understood. The transcriptomic profiles of ontogenetic and regenerating scales of zebrafish were determined and identified differentially expressed genes that were enriched for extracellular matrix, ossification, and cell adhesion pathways. These results indicate that scales are reminiscent to bone. Hypergeometric tests involving monogenetic skeletal disorders showed that DEGs were strongly enriched for human orthologues that are mutated in low bone mass and abnormal bone mineralisation diseases. The DEGs were also enriched for human orthologues associated with polygenetic skeletal traits, including height and estimated bone mineral density. Despite the many differences between scale and endoskeletal developmental processes, our publication in BMC Biology shows that zebrafish scales express an evolutionarily conserved sub-population of genes that are relevant to human skeletal disease.