Transcriptome-based screening and validation of key genes for wool color in cashmere goats

Background Colored wool from cashmere goats is increasingly popular among consumers, but the transcriptomic differences between coat colors are poorly understood. Objectives This study aimed to screen for coat color regulation-associated genes in cashmere goats to ascertain their underlying molecular mechanisms. Methods Transcriptomic sequencing of skin tissues from black (BC), brown (YC), and white cashmere (WC) goats was performed. Immunohistochemistry and western blotting were used to validate SLC24A4 and DCT expression, two essential genes identified for coat color determination. Results We identified 6,518 differentially expressed genes (DEGs) in the BC vs. WC group (3,919 upregulated, 2,599 downregulated). Next, 5,593 DEGs were identified in the YC vs. WC group (3,629 upregulated, 1,964 downregulated). Finally, 4,538 DEGs were expressed in both groups, with 1,980 and 1,055 DEGs exclusively expressed in either group. Functions and pathways associated with hair color were enriched, including melanosomes, melanocyte migration, melanin biosynthesis processes and functions, and melanogenesis pathways. TYRP1 , SLC24A4 , PMEL , OCA2 , and DCT were significantly upregulated in BC goat skin, while ASIP was significantly upregulated in YC skin. Additionally, KIT , POMC , SLC24A5 , Wnt3a , and EDN3 were DEGs for different coat colors. Immunohistochemistry revealed SLC24A4 and DCT expression in dermal papillae, inner and outer root sheaths, and the hair follicle matrix. Western blotting showed that SLC24A4 protein levels were highest in BC goat skin. DCT protein levels were also highest in BC goat skin, albeit not significantly. Conclusion These results further our understanding of coat color regulation in cashmere goats, establishing a foundation for their molecular breeding.