Fgf21 knockout mice generated using CRISPR/Cas9 reveal genetic alterations that may affect hair growth

To investigate fibroblast growth factor 21 (Fgf21) alterations that may affect hair growth and the underlying molecular mechanisms by constructing Fgf21 global knockout (KO) mice using microinjection-mediated CRISPR/Cas9.

Following genomic DNA sequencing, we identified 18 mice carrying Ffg21 mutations among the total 63 offspring mice obtained by injecting 340 embryos, which yielded a mutation rate of 28.6 percent. Of these 18 mice, three had both alleles knocked out and 15 were monoallelic KO mice. Compared with the wild-type (WT) mice, the phenotypic analysis showed that the litter size of Fgf21 KO mice significantly reduced (p < 0.05), but physiological indexes of the birth weight, gender rate, body weight (0-8 week) and body weight of adult male and female were no significant difference (p > 0.05). Compared to WT mice, physiological anatomy indicated that the morphological characters of vital organs in Fgf21 KO mice were normal. Depilation experiments demonstrated that compared to the WT mice, the hair regrowth speed was reduced in the Fgf21 KO mice. The number of hair shafts in these mice considerably decreased, as indicated by the tissue sample analyses. Real-time quantitative PCR showed that Erk and Akt expression in the KO mice was significantly decreased (P < 0.05), whereas western blotting demonstrated that the expression of Erk and Akt proteins and their phosphorylation levels in KO mice decreased at different rates (P < 0.05).

Fgf21 was shown to affect hair follicle development and growth cycle, which may be associated with Pi3k/Akt and Mapk/Erk signaling pathways.