Zebrafish keratin 8 is expressed at high levels in the epidermis of regenerating caudal fin

Cytokeratins are structural proteins of the intermediate filament family an d are mainly expressed in epithelial cells. In several vertebrates it has b een shown that keratin 8 is expressed in simple epithelial tissues, some no n-epithelial tissue and in hyper-proliferative tissues during development a nd tumor transformation. We previously cloned and characterised the zebrafi sh (Danio rerio) homologous cytokeratin 8 cDNA (zfk8) which was described a s an epidermal marker during zebrafish development. It has been found that the zfk8 gene is normally expressed in simple epithelia in embryonic and ma ture zebrafish. Using whole-mount in situ hybridisation, we show in this re port that expression of zfk8 is tightly linked to the regeneration of cauda l fin and exclusively observed in epidermal cells. It is strongly expressed in the epidermis overlaying the inter-rays zone of regenerating caudal fin . Our results indicate that in zebrafish, cytokeratin 8 is a suitable epide rmal marker during regeneration.