Cystine Promotes the Development of Hair Follicle in Rabbits by Regulating Wnt Signalling Pathway

Amino acids are extremely important nutrients in the feed for fur-bearing animals, and this study was conducted to evaluate the effects of cystine on the development of hair follicles in Rex rabbits. A total of 224 Rex rabbits at the age of 90 days were randomly divided into 4 groups and fed the diets supplemented with 0 (Control), 0.2%, 0.4%, or 0.6% cystine, and the rabbits were fed for 60 days. The hair follicle density on the dorsal skin and the gene expression and protein phosphorylation levels of components of Wnt signalling pathways were determined. In addition, the dermal papilla cells (DPCs) were isolated from the skin of Rex rabbits and cultured with cystine in vitro to determine the gene expression and protein phosphorylation levels of Wnt signalling pathways. The results showed that addition of cystine in the diets could increase the fur quality (p < 0.05), and the appropriate of cystine in Rex rabbits' diets was 0.2%. In addition, cystine added to the cell culture medium changed the DPCs cycle progression and promoted cell proliferation. Furthermore, cystine could affect the Wnt10b, CTNNB1, and Dickkopf-1 gene expression of Wnt signalling pathways in the skin and DPCs of rabbits (p < 0.05), and decreased the levels of phosphorylated CTNNB1 and GSK-3β of Wnt signalling pathways in the skin and DPCs of rabbits (p < 0.05). Dietary cystine supplemental level could promote the fur quality of Rex rabbits, and the appropriate of cystine in Rex rabbit diets was 0.2%. Furthermore, the molecular mechanism of cystine modulates hair follicle development, probably occurs through activation of Wnt signalling pathways, promotes DPCs proliferation, and increases the hair density of Rex rabbits.