Department of Dermatology
Medical University of Vienna

Abstract

Cornified skin appendages, such as claws, hair and feathers, are major evolutionary innovations of terrestrial vertebrates. Human hair and nails consist of keratins, which are expressed under the control of the transcription factor Hoxc13. To determine the evolutionary history of skin appendages at the molecular level, we performed comparative genomics, gene expression and genome editing studies. We could demonstrate that homologs of hair keratins are present in the claws of reptiles and Xenopus frogs, and Hoxc13 controls claw keratins in Xenopus tropicalis. Our results suggest a scenario in which the evolution of cornified skin appendages is linked to the evolution of body appendages through Hox-dependent gene expression.