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. Conclusion: The growth cycle of cashmere cashmere could be divided into three distinct periods: a growth period (March–September), a regression period (September–December) and a resting period (December–March). March was considered to be the beginning of the cycle. KAP and KRTAP showed close positive correlation with the growth cycle of secondary hair follicle cashmere growth, and their regulation was consistent with the cashmere growth cycle. But hair follicle development-related genes are expressed earlier than cashmere growth, indicating that cycle regulation could alter the temporal growth of cashmere. This study laid a theoretical foundation for the study of the cashmere development cycle and provided evidence for key genes during transition through the cashmere cycle. Our study provides a theoretical basis for cashmere goat breeding.

Whole-genome sequencing of Chinese native goat offers biological insights into cashmere fiber formation

“…Among these genes, LHX2 functions as a transcriptional activator in hair follicle stem cells and is an essential positive regulator of hair formation (RheePolak and Fuchs 2006;Tornqvist et al 2010). Furthermore, the expression of LHX2 was upregulated during hair follicle differentiation, and the expression abundance was constant throughout the development cycle in secondary hair follicles of cashmere goats (Wu et al 2020;Yang et al 2020). In contrast, DENND1A and CRB2, which function in endocytic trafficking to mediate the recycling of selective cargos and early embryonic development, respectively (Xiao et al 2011;Shi et al 2019), were expressed lowly in the fetal stage of goat skin and showed very low expression during the cycle of adult cashmere fiber growth (Fig.…”

“…18 and 19). It is known that cashmere fiber growth has three different periods in one year: a growth period (March-September), a regression period (September-December), and a resting period (December-March) (Yang et al 2020). Therefore, the deletion of the LHX2 insulator increases the expression of LHX2 and promotes cashmere fiber growth at the anagen stage, while deletion of the FGF5 enhancer reduces the expression of FGF5, inhibiting the regression.…”

Time-course RNA-seq analysis reveals stage-specific and melatonin-triggered gene expression patterns during the hair follicle growth cycle in Capra hircus

“…Under the periodic changes of the natural photoperiod, the growth of cashmere in the Inner Mongolian cashmere goat presents a seasonal pattern. Normally, a typical hair follicle growth cycle starts in July and stops in March of the following year with shedding of the cashmere at April [5].…”

“…The hair follicle growth cycle of the cashmere goat can be divided into three phases: anagen, catagen and telogen, which are regulated by specific genetic regulators [5]. For Inner Mongolian cashmere goats, the anagen phase of SHFs is from April to November, the catagen phase is from December to January, and the telogen phase is from February to March [12].…”

“…With the rapid development of high-throughput sequencing technology, some regulatory factors and signaling pathways involved in the hair follicle cycle have been found through differential expression and functional enrichment analysis. These well-known regulatory molecules and signaling pathways include Wnt/β-catenin [14][15][16], bone morphogenetic proteins (BMPs) [17,18], sonic hedgehog (SHH) [19], notch [20], fibroblast growth factors (FGFs) [21], transforming growth factors (TGFs) [22] and keratin-associated proteins (KRTAPs) [5,23], etc.…”