Fibroblast growth factor 22 and its potential role during skin development and repair.

We have isolated, using RT-PCR, a cDNA from mouse skin wounds that encodes fibroblast growth factor (FGF) 22, a recently discovered member of the FGF family, which is closely related to FGF-7 and FGF-10. Transient expression of tagged FGF-22 protein in COS-1 and MCF-7 cells revealed that the protein was present within the cell and at the cell surface but was not apparently released from the cell. Analysis of RNA expression revealed that FGF-22 transcripts were not detected in the developing mouse embryo until day E16.5 and in the adult mouse it was expressed in the brain, tongue, and skin, but not in other tissues examined. After skin injury, FGF-22 mRNA levels were slightly down-regulated within the first 5 days after wounding, but expression increased strongly at the later stages of the repair process. In situ hybridization revealed the presence of FGF-22 mRNA throughout the epidermis and hair follicle keratinocytes of E16.5 embryos, as well as in adult skin and keratinocytes of the hyperthickened wound epithelium. This expression pattern suggests a potential role for FGF-22 in cutaneous development and repair.