Regulation Of NR1D2 On The Cycle Regeneration Of The Hair Follicle Of Shanbei White Cashmere Goat Under The Natural Photoperiod

Cashmere goats are animals with seasonal changes in hair growth.The hairs are composed of thick wool and cashmere,which are produced by primary hair follicles and secondary hair follicles,respectively.The cashmere shows a typical periodic growth pattern,which makes it as a model for studying the mechanism of hair regeneration cycle.Under the natural photoperiod,the cashmere undergoes a cycle of the anagen,catagen and telogen.Photoperiod is one of the main factors controlling the seasonal variation of cashmere,and related genes that affect the rhythm change of cashmere growth may play a key role in hair follicle growth.The biological rhythmic changes are often regulated by clock genes.It remains to be studied whether these clock genes will contribute to the cycle change of cashmere.Therefore,in this study,Shanbei White Cashmere goat was used as the experimental material.In order to uncover the mechanism of the periodical growth of the hair follicle,the possible biological clock genes and roles were studied under the natural photoperiod.The main contents included:(1)Observing the changes of hair follicles in different periods of Shanbei White Cashmere goat by immunohistochemistry and HE staining,exploring the changes in the expression of circadian clock genes in the cycle of hair follicles,and screening important circadian clock genes based on tissue expression results;(2)Based on the screened Nr1d2 gene,investigating miRNA that may have an effect on NR1D2 expression,screening the miRNA through the dual luciferase reporting detection system and verifying their targeting relationship with the Nr1d2 gene.The main findings are as follows:1.Correlation analysis of the growth status of cashmere and environmental factors revealed that the growth of cashmere had a certain correlation with environmental factors such as solar,temperature,and relative humidity.Among them,the environmental factor of solar had the highest correlation with the growth of cashmere.By detecting the expression of circadian clock genes in skin samples during anagen,catagen and telogen of Shanbei White Cashmere goat,the expression levels were not significantly different.Combined with the localization of the circadian clock gene in the skin in the immunohistochemistry,it was found that NR1D2 was expressed in the outer root sheath and hair bulbs during the anagen.Finally,we screened the Nr1d2 gene as a key gene and examined the protein expression level.It was found that NR1D2 protein expression was highest in the skin tissue during the growth period.2.Using miRbase,we screened two miRNA(chi-miR-128-3p and chi-miR-218)targeting the Nr1d2 gene.We determined chi-miR-218 had a targeting relationship with the Nr1d2 gene by dual luciferase reporter detection system.Over-expressed chi-miR-218 significantly inhibited the expression of the Nr1d2 gene and interfered with the expression of the NR1D2 protein.It was found that the expression of chi-miR-218 in different periods was different,and it was highly expressed during the telogen;then we tested the effect of chi-miR-218 on apoptosis,and the results showed that chi-miR-218 could promote cell apoptosis.In conclusion,light had a close relationship with cashmere growth.Under the conditions of natural photoperiod,according to the localization of the clock gene on hair follicle tissues of Shanbei White Cashmere goat and the change of protein expression at different periods,the important biological clock gene Nr1d2 was screened,and the chi-miR-218 was targeted to the Nr1d2 gene.Over-expression of chi-miR-218 in hair follicle cells affected the expression of Nr1d2 gene,which provided a foundation for further revealing the regulation mechanism of the hair follicle cycle.