Determination of Secondary Follicle Characteristics, Density, Activity, and Hoxc13 Expression Pattern of Hexi Cashmere Goats Breed

Molecular Genetic Characteristics of the Hoxc13 Gene and Association Analysis of Wool Traits

Homobox C13 (Hoxc13) is an important transcription factor in hair follicle cycle development, and its deletion had been found in a variety of animals leading to abnormal hair growth and disruption of the hair follicle system. In this study, we used immunofluorescence, immunohistochemistry, real-time fluorescence quantitative PCR (RT-qPCR), and Kompetitive Allele-Specific PCR (KASP) genotyping to investigate molecular genetic characteristics of the Hoxc13 gene in Gansu alpine fine-wool sheep. The results revealed that Hoxc13 was significantly expressed during both the anagen and catagen phases (p < 0.05). It was found to be highly expressed predominantly in the dermal papillae and the inner and outer root sheaths, showing a distinct spatiotemporal expression pattern. Two single nucleotide polymorphisms (SNPs) in the exon 1 of Hoxc13, both the individual locus genotypes and the combined haplotypes were found to be correlated with wool length (p < 0.05). It was determined the mutations led to changes in mRNA expression, in which higher expression of this gene was related with longer wool length. In summary, this unique spatiotemporal expression pattern of the Hoxc13 gene may regulate the wool length of Gansu alpine fine-wool sheep, which can be used as a molecular genetic marker for wool traits and thus improve the breed.

Histological characteristics of hair follicles at different hair cycle and in vitro modeling of hair follicle-associated cells of yak (Bos grunniens)

To adapt to the extreme conditions of plateau environments, yaks have evolved thick hair, making them an ideal model for investigating the mechanisms involved in hair growth. We can gain valuable insights into how hair follicles develop and their cyclic growth in challenging environments by studying yaks. However, the lack of essential data on yak hair follicle histology and the absence of in vitro cell models for hair follicles serve as a limitation to such research objectives. In this study, we investigated the structure of skin tissue during different hair follicle cycles using the yak model. Additionally, we successfully established in vitro models of hair follicle-associated cells derived from yak skin, including dermal papilla cells (DPCs), preadipocytes, and fibroblasts. We optimized the microdissection technique for DPCs culture by simplifying the procedure and reducing the time required. Furthermore, we improved the methodology used to differentiate yak preadipocytes into mature adipocytes, thus increasing the differentiation efficiency. The introduction of yak as a natural model provides valuable research resources for exploring the mechanisms of hair growth and contributes to a deeper understanding of hair follicle biology and the development of regenerative medicine strategies.

Altered Hypoxia-Induced and Heat Shock Protein Immunostaining in Secondary Hair Follicles Associated with Changes in Altitude and Temperature in Tibetan Cashmere Goats

This experiment compared secondary hair follicles (SFs) in Tibetan cashmere goats from two different steppes that were at different altitudes and had different temperatures. Twenty-four 2-year-old goats were studied. Twelve goats were from Rikaze in Tibet which is at an altitude of above 5000 m with an average temperature of 0 °C. The other 12 studied goats were from Huan County of Gansu Province which is around 2000 m above sea level with an average temperature of 9.2 °C. The structural features of SFs were assessed using light microscopy and transmission electron microscopy. The presence of HIF-1a, HIF-2a, HIF-3a, HSP27, and HOXC13 proteins was studied using immunohistochemistry and immunofluorescence. Light and electron microscopy revealed that the SFs of the Tibetan cashmere goats that lived in the Rikaze Steppe were in the proanagen stage in May. However, the SFs of the goats from the lower warmer Huan County were in the anagen stage at the same time. Immunohistochemistry revealed intense immunostaining for HIF-1a protein in the inner root sheath (IRS) and hair shaft (HS); immunostaining against HIF-2a in the outer root sheath (ORS) and IRS; HIF-3a protein immunostaining in the ORS; HSP27 immunostaining in the ORS, IRS, and HS; and HOXC13 immunostaining in the ORS and HS. HIF-1a protein expression in the IRS and HS was higher than the expression in the ORS (p < 0.05) while the expression of HIF-2a protein was higher in the ORS and IRS than the HS (p < 0.05). The expression of HIF-3a protein was higher in the ORS than in the IRS (p < 0.05). Expression of HOXC13 protein was higher in the ORS than in the IRS and HS (p < 0.05). Immunostaining of HIF-1a, HIF-2a, and HSP27 protein was significantly higher in SFs from cashmere goats from Rikaze than in goats from Huan (p < 0.05). In contrast, HOX13 protein immunostaining was significantly higher in cashmere goats from Huan than from Rikaze (p < 0.05). Significant differences were observed in the SFs of cashmere goats from two locations that differ in altitude and temperature. This suggests the differences in the secondary hair follicles could be due to the hypoxia and lower temperatures experienced by the goats in Rikaze. These results are useful in understanding how altitude and temperature influence SF development. Hair produced by the SFs are used for down fiber. Therefore, understanding of the factors that influence SF development will allow the production and harvest of these valuable fibers to be maximized.

The disrupted balance between hair follicles and sebaceous glands in Hoxc13-ablated rabbits

Pure hair and nail ectodermal dysplasia 9 (ECTD-9) is an autosomal recessive genetic disease caused by mutation of HOXC13 and is characterized by hypotrichosis and nail dystrophy in humans. Unlike patients with ECTD-9, Hoxc13-mutated mice and pigs do not faithfully recapitulate the phenotype of hypotrichosis, so there is a limited understanding of the molecular mechanism of Hoxc13-mediated hypotrichosis in animal models and clinically. Here, the homozygous Hoxc13^-/- rabbits showed complete loss of hair on the head and dorsum, whereas hypotrichosis in the limbs and tail were determined in the Hoxc13^-/- rabbits. In addition, reduced hair follicles (HFs) while the enlarged and increased number of sebaceous glands (SGs) were also found in the Hoxc13^-/- rabbits, showing that the disrupted balance between HFs and SGs may respond to hypotrichosis of ECTD-9 in an animal model and clinically. Therefore, our findings demonstrate that Hoxc13^-/- rabbits can be used as a model for human ECTD-9, especially to understand the pathologic mechanism of hypotrichosis. Moreover, the disrupted balance between HFs and SGs, especially in the Hoxc13^-/- rabbits, can be used as an ideal animal model for dermatology ailments, such as acne and hypotrichosis, in preclinical studies.-Deng, J., Chen, M., Liu, Z., Song, Y., Sui, T., Lai, L., Li, Z. The disrupted balance between hair follicles and sebaceous glands in Hoxc13-ablated rabbits.

HOXC13 and HSP27 Expression in Skin and the Periodic Growth of Secondary Fiber Follicles from Longdong Cashmere Goats Raised in Different Production Systems

This experiment was conducted to identify periodic changes in secondary follicles (SFs) over one year of extensive (grazed) and intensive (housed and fed supplement) farming of Longdong cashmere goats. One-year old goats (n = 24, 12 extensively fed and 12 intensively fed) were studied. The diameter, depth, density, activity, and ultra-structural features of SFs were assessed using light microscopy and transmission electron microscopy. HOXC13 and HSP27 expression were studied using immunohistochemistry and immunofluorescence method. The anagen stage in the extensively grazed goats was from April to September, but was longer (April to October) in the housed, supplementary fed group. The depth and activity of the SF in anagen and catagen differed (P < 0.05) between the groups. HSP27 and HOXC13 protein were present in both the epidermis and dermis, with HSP27 immunoreactivity highest in the hair shaft (HS), outer root sheath (ORS) and inner root sheath (IRS). HOXC13 expression was prominent in both the eprdermis and ORS. HSP27 and HOXC13 expression were prominent during anagen, and less so during catagen and telogen. In anagen, HSP27 expression in the HS, IRS, and ORS of the extensively fed group was higher than in the intensively fed group (p < 0.05). In contrast, HOXC13 expression in HS, IRS and ORS of the extensively fed group was lower than in the intensively fed group (P < 0.05). This suggests the growth of cashmere is influenced by nutrition and that housed goats could be used in cashmere production. Anat Rec, 301:742-752, 2018. © 2017 Wiley Periodicals, Inc.