Study On The Localization And Expression Of FGF21 And Receptor FGFR1?2 To Hair Follicle Formation And Development In Mouce

Hair follicle is an important organ of animal hair generation,and its growth and development are regulated by various signal pathways,among which FGF family and its receptor FGFR family have an important influence on the growth and development of hair follicle.The formation of hair follicles starts from the 13th day of mouse embryonic stage and goes into the next growth cycle after three stages,namely,anagen,catagen,telogen.Research shows that many members of FGF family have certain regulatory effect on the growth cycle of hair follicles,but there is little research on the effect of FGF21 on hair follicles.only in 2017,Zhang ping et al found that FGF21 induced hair follicles to enter the degeneration stage from the growth stage,and other studies showed that FGFR1 might promote the migration of mouse skin cells in the embryonic stage,FGFR2 gene deletion would cause mouse skin dysplasia,but the research on FGF21 and its receptors FGFR1 and FGFR2 in the hair follicle formation stage and the first growth cycle after birth has not been reported.In this study,13 to 18 days(e13-e18)of embryonic mice and 1 to 25 days after birth were selected,and their corresponding growth cycle days were determined by HE staining technology.The distribution of FGF21,FGFR1,FGFR2 protein in the skin of mice back was determined by immunohistochemistry technique.The gene and protein expression of FGF21,FGFR1,FGFR2 in mouse dorsal skin was quantitatively analyzed by Real-time PCR and Western blot analysis.The results were as follows:In mouse hair follicle formation periods,(1)IHC-P experiment showed that the expression of FGF21 at E13 day was mainly expressed in the epidermis,in the basal layer and hair germ at 14th day.During E13-E18,FGFR 1 protein were located in epidermis cells,hair peg and hair germ.FGFR2 was expressed in epidermis and hair matrix.(2)RT-PCR and Western blot analysis showed that the expression of FGF21 gene and protein was highly found on E13,E14 and E17.The expression of FGFR1 gene and protein was higher in the whole embryonic stage.However,the expression of FGFR2 gene and protein showed a decreasing trend from E13 days to E15 days.The expression of FGFR2 gene and protein increased again on E16 days and then decreased after E13 days to E15 days.In the first hair growth cycle:(1)IHC-P results showed that FGF21,FGFR1,FGFR2 was located in the hair follicle dermal papilla,hair matrix,root sheath and sebaceous glands.FGF21 was mainly expressed in the dermal papilla and outer root sheath.FGFR1 was mainiy expressed in the dermal papilla and the inner root sheath.FGFR2 was mainly expressed in the dermal papilla and the outer root sheath.The results of RT-PCR and Western blot analysis showed that the FGF21 gene and protein began to decrease from the first day after birth.On the 8th day after birth,the expression of FGFR21 reached the lowest level,and then increased.The expression of FGFR21 reached the highest level on the 23d day of birth.The expression level of FGFR1 and FGFR2 decreased from 1 day to the lowest at 8d,and increased from 12d until 17d,decreased in 21d and 23d.Conclusion:(1)in the hair follicle formation stage,FGF21 may determine the position of hair follicle growth and affect the formation of hair papilla at the same time;FGFR1 founction has no obvious trend.FGFR2 plays an important role in hair follicle formation.(2)in the first hair follicle growth cycle after birth,FGF21 may promote the transition of hair follicles from catagen to telogen.FGFR1 may control the growth direction of hair follicles,promote the apoptosis of hair follicle structures and make the hair follicles enter the exogen from telogen.FGFR2 may induce the growth and differentiation of fibroblasts in hair follicles and promote the hair follicles from telogen to exogen.