Molecular Mechanism Of Hair Follicle Regional Specificity In Mongolian Horse

Horse has a variety of hair types,mainly divided into mane,dorsal part,tail and fetlock.The regional specificity for studying the development of different types of hair follicles in one individual,which is of significant research value.However,due to limitations of animal welfare and difficulties in sample collection,there are few researches on horse hair follicles in domestic and overseas,and researches in this field is not systematic.Mammal hair growth is a dynamic process that relies on the proliferation,differentiation and migration of different types of cells in skin and hair follicle.To explore how hair types in different parts of the horse regulate and maintain relatively independent hair follicle cycles and morphogenesis and how pigment stem cells migrate to synthesize pigment are of important theoretical significance.Mongolian horse is one of the oldest horse breeds in China and has a profound influence in Mongolian culture.Inner Mongolia Autonomous Region,as the largest Mongolian horse producing area in China,has abundant Mongolian horse germplasm resources.Therefore,understanding the hair growth,cycle and pigment synthesis of Mongolian horse can provide reference for breeding high quality horse breeds.Mongolian horse coat color is various.In this research,among Mongolian horse colors,the most common bay Mongolian horses were selected as research objects.The histological technique was used to analyze the hair follicle morphological differences in different parts of Mongolian horses from the perspective of hair follicles.The molecular mechanism of hair follicle morphogenesis and pigment synthesis was explored and further verified by experiments.The main conclusions were obtained through this research as follows:1.Histological studies showed that the hair follicles in different parts of the Mongolian horse have different morphological characteristics,but all have the basic structure of hair follicle.The hair follicle pigmentation of the dorsal part was composed of two types of pigments:eumelanin and phaeomelanin,and the other three parts were all eumelanin.The hair follicle density varied in different parts,and the hair follicle diameter was also different.The hair follicle cycle was different in different parts in this study.2.Histochemical staining results showed that alkaline phosphatase was present in glandular or vascular-like tissues around the hair follicles in different parts of the Mongolian horse.It was also found in the hair bulb of mane,tail and fetlock skin hair follicles.Compared with the other three parts,strongest ALP expression was found in fetlock skin,there was a strong signal expressed above the dermis.The stem cell marker K15 protein was expressed in different parts of the epidermis and outer root sheath of the bay Mongolian horse.3.By adding prokaryotic ribosome probe to capture the contamination of rRNA,the mRNA library of different parts of the skin of Mongolian horse was successfully constructed,and 196.49G valid date was obtained after quality control.Principal component analysis and the number of differentially expressed genes in the range of P values consistently showed that the differences between dorsal part and the other three parts was bigger than that between the other three parts.4.By comparing the differentially expressed genes between different part skin tissues in the bay Mongolian horse,some important genes were selected from the upstream and downstream of the melanogenesis pathway.The regulation between these genes ultimately affected the pigmentation of hair follicles.Genes of Wnt family related to hair follicle morphogenesis were selected,and insulin factors related to hair follicle cycle and angiogenesis were also enriched.GO terms were enriched in pigment synthesis,insulin and Wnt relevant signaling pathways.Stem cell-related signaling pathways between different parts had also been enriched.Angiogenesis-related signaling pathways were enriched between the relatively thick hair follicle parts,such as mane,tail and fetlock.5.The mRNA and protein expression trend of the candidate genes related to hair follicle morphological development and pigment synthesis in different parts of bay Mongolian horses was different,and the regulation trend is also inconsistent.This is closely related to the period of hair follicles;or Non-coding RNA is also involved in the process of protein translation.In mRNA expression.6.The miRNA library of different parts of the skin of bay Mongolian horse was successfully constructed.Different methods all showed that the dorsal part skin tissue was less correlated with the samples of the other three parts,which was consistent with the previous results on mRNA.Screening of candidate differentially expressed miRNAs between different parts showed that some miRNAs associated with hair follicle morphological development and pigment synthesis had higher expression level.After enriching the genes targeted by the differentially expressed miRNAs using KEGG,three kind of candidate pathways related to hair follicle morphological development and pigment synthesis were mainly enriched:Wnt,stem cell-associated and insulin-related signaling pathways.The results were also consistent with mRNA above.