Proteomics analysis of the secondary hair follicle cycle in Liaoning cashmere goat

Cashmere is an important economic resource for the agricultural industry. The secondary hair follicle cycle can control the yield and quality of cashmere. Therefore, to improve the yield and quality of cashmere in Liaoning cashmere goats, an understanding of the skin proteomic changes in the secondary hair follicle cycle is needed. In this study, we used a label-free proteomics approach to analyze the protein expression profile of the secondary hair follicle cycle at three stages (telogen, anagen, and catagen) in goat neck skin. Proteomics, bioinformatics, and immunofluorescence assays were employed. We identified 57 differentially abundant proteins (DAPs) and discovered that the proteins of the keratin family were highly expressed in the anagen and catagen phases. The analyses indicated that nine keratin proteins (KRT25, KRT27, KRT19, KRT10, KRT77, KRT1, KRT24, KRT14, and KRT4) can be regarded as markers of the hair follicle cycle. KRT1 was located in both the inner and outer root sheath, whereas KRT14 was located in the inner root sheath and KRT19 only in the outer sheath. Phylogenetic analysis showed that these nine keratin proteins have common evolutionary precursors, and each category has similar expression patterns. Functional enrichment analysis indicated that the estrogen and ECM-receptor interaction signaling pathways play important roles in secondary hair follicle phases/cycles. These findings provide an important resource for protein information related to cashmere goats, and the identified DAPs can be further applied to improve cashmere quality and production.