Skin transcriptome reveals the periodic changes in genes underlying cashmere (ground hair) follicle transition in cashmere goats

Abstract

Background: Cashmere goats make an outstanding contribution to the livestock textile industry and their cashmere is famous for its slenderness and softness and has been extensively studied. However, there are few reports on the molecular regulatory mechanisms of the secondary hair follicle growth cycle in cashmere goats. In order to explore the regular transition through the follicle cycle and the role of key genes in this cycle, we used a transcriptome sequencing technique to sequence the skin of Inner Mongolian cashmere goats during different months. We analyzed the variation and difference in genes throughout the whole hair follicle cycle. We then verified the regulatory mechanism of the cashmere goat secondary hair follicle growth cycle using fluorescence quantitative PCR. Results: The growth cycle of cashmere hair could be divided into three distinct periods: a growth period (March-September), a regression period (September-December), and a resting period (December-March). The results of differential gene analyses showed that March was the most significant month. Cluster analysis of gene expression throughout the whole growth cycle further supported the key nodes of the three periods of cashmere growth, and the differential gene expression of keratin corresponding to the ground haircashmere growth cycle further supported the results from tissue slices. Quantitative fluorescence analysis showed that KAP3-1, KRTAP 8-1, and KRTAP 24-1 genes had close positive correlation with the cashmere growth cycle, and their regulation was consistent with the growth cycle of cashmere.

Identification of Key Pathways and Genes Related to the Development of Hair Follicle Cycle in Cashmere Goats

“…Thus, combined the morphological changes of hair follicle [ 18 ], Jan. and Aug., Feb. and May should not be in same stages, respectively. However, the periodical development of hair follicle was induced by the cyclical fluctuation of gene expression, and their expression patterns between different months (Feb. and May, Jan. and Aug.) may be similar and clustered together.…”

“…Indeed, the growth traits of HFs in last-telogen are the lowest value in histology throughout HFC [ 3 , 7 , 18 ], but some people thought last-telogen is the master-switch that controls HFC by retaining hair fibers with minimal energy expenditure and responding to a variety of stimuli to launch a new regeneration cycle [ 80 , 86 ]. In this study, genes in ME brown and ME magenta associated with last-telogen were involved in metabolic process and stimulus response and immunity, respectively ( Table 1 , Supplementary Materials Tables S3 and S4 ).…”

“…According to the characteristics of the growth and development of HFs in cashmere goat over 12 months [ 18 ], we divided the development of HFs into four stages: anagen (April–September), catagen (October and November), telogen (December–February), last-telogen (March). In this study, the key modules related to the periodic regeneration of cashmere goat hair follicle were determined by calculating gene significance (GS) and module membership (MM) values simultaneously [ 38 ].…”

“…Raw data (SRP145408) in this study were downloaded from the Sequence Read Archive database of the NCBI (https://www.ncbi.nlm.nih.gov/) [18]. This dataset contained transcriptome sequencing information from skin tissues of three adult Inner Mongolia cashmere goats collected continuously once a month for 12 months.…”

“…With the rapid development of high-throughput sequencing technology, some regulatory factors and signal pathways involved in the hair follicle cycle (HFC) have been found through differential expression gene (DEG) analysis and functional enrichment analysis. These well-known regulatory molecules and signal pathways include Wnt/β-catenin [ 9 , 10 , 11 ], bone morphogenetic proteins (BMPs) [ 12 , 13 ], sonic hedgehog (SHH) [ 14 ], notch [ 15 ], fibroblast growth factors (FGFs) [ 16 ], transforming growth factors (TGFs) [ 17 ] and keratin-associated proteins (KRTAPs) [ 18 ], etc. Most of them were reported in mice and human, but for cashmere goat with a double-coat some other uncommon regulatory molecules, different signal pathways may be involved.…”