Paxbp1 Is Indispensable for the Maintenance of Epidermal Homeostasis.

The mammalian epidermis is a structurally complex tissue that serves critical barrier functions, safeguarding the organism from the external milieu. The development of the epidermis is governed by sophisticated regulatory processes. However, the precise mechanism maintaining epidermal homeostasis remains incompletely elucidated. Recent studies have identified Paxbp1, an evolutionarily conserved protein, as being involved in the developmental regulation of various cells, tissues, and organs. Nonetheless, its role in skin development has not been explored. In this study, we report that the targeted deletion of Paxbp1 in epidermal keratinocytes mediated by keratin 14-Cre leads to severe disruption in skin architecture. Mice deficient in Paxbp1 exhibited a substantially reduced epidermal thickness and pronounced separation at the dermal-epidermal junction upon birth. Mechanistically, we demonstrate that the absence of Paxbp1 hinders cellular proliferation, marked by a halt in cell cycle transition, suppressed gene expression of proliferation, and a compromised DNA replication pathway in basal keratinocytes, resulting in the thinning of the skin epidermis. Moreover, molecules and pathways associated with hemidesmosome assembly were impaired in Paxbp1-deficient keratinocytes, culminating in the detachment of the skin epidermal layer. Therefore, our study highlights an indispensable role of Paxbp1 in the maintenance of epidermal homeostasis.