Cornifelin expression during Xenopus laevis metamorphosis and in response to spinal cord injury

In a high-throughput RNA sequencing analysis, comparing the transcriptional response between Xenopus laevis regenerative and non-regenerative stages to spinal cord injury, cornifelin was found among the most highly differentially expressed genes. Cornifelin is mainly expressed in stratified squamous epithelia, but its expression in the spinal cord and other central nervous structures has only been described during early development. Here, we report cornifelin expression in the spinal cord, retina, and cornea throughout metamorphosis and in the spinal cord after injury. Cornifelin was detected in the grey matter and meninges of the spinal cord from NF-50 to NF-66, with decreased expression in the grey matter during metamorphosis. In the retina, cornifelin was expressed in the ganglion cell layer, the inner and outer nuclear layer, and the outer segment from NF-50 to NF-66. After spinal cord injury, we only observed cornifelin upregulation in NF-66 but no significant changes in NF-50. However, we found cornifelin positive cells in NF-50 meninges closing the spinal cord stumps 1 day after injury and delineating the borders of the spinal cord following the continuity of tissue regeneration in the following days after injury. Instead, in NF-66, cornifelin positive cells were distributed to the ventral side of the spinal cord at 6 days after injury, and at the injury gap at 10 days after injury. Cornifelin is expressed in the Xenopus laevis spinal cord and eye during metamorphosis and plays a role in the meningeal response to spinal cord injury.