Neotenic phenomenon in gene expression in the skin of Foxn1 deficient (nude) mice– projection for regenerative skin wound healing

Uninjured skin of adult C57BL/6J mice and mouse fetuses at 18 day of embryonic development (E18), as the models of reparative healing, and Nude and E14, as the models of regenerative healing, were characterized for their gene expression profiles by next-generation high-throughput DNA sequencing. The comparisons of gene expression profiles indicated that there were more similarities within each model of healing (Nude was more similar to E14 and B6 was more similar to E18). The analysis revealed that Nude and E14 showed in common the up-regulation of genes associated with tissue remodeling, cytoskeletal rearrangements, wound healing and immune response and the down-regulation of genes coupled to differentiation. Gene expression profiles of regenerative adult Nude mice display features of an attenuated skin development resembling that of E14 mice, thus the Nude mouse may be considered as a unique example of neoteny among mammals. The similar expression profiles of genes in the skin of both Nude and E14 mice are direct or indirect consequences of FOXN1 deficiency. FOXN1 appears to regulate the balance between cell proliferation and differentiation and its lack creates a pro-regenerative environment.