Comparative ultrastructural and transcriptomic profile analysis of skin tissues from indigenous, improved meat, and dairy goat breeds.

Background: High-quality goatskins are valuable byproducts usually produced by indigenous goat breeds with poorer production performance in Asia and Africa. However, the genetic and molecular mechanisms underpinning goatskin's biomechanical properties (e.g., tensile strength) remain elusive. Mechanistic exploration of these traits could greatly aid the genetic improvement and genetic resource conservation of native breeds in these regions. To fulfill this purpose, we collected skin tissues from three goat breeds: Huai goat (HG), a Chinese native variety producing high-quality goatskins; Yudong meat goat (YDMG), a crossbreed of HG and Boer goat; Henan dairy goat (HNDG), a dairy goat breed.

Results: Scanning electronic microscopy analysis of skin tissues found that the collagen fiber diameters, collagen fibril diameters, and crimps significantly differed among the three goat breeds; however, collagen fibril diameters are similar in HG and HNDG. A sum of 230, 775, and 86 differentially expressed genes (DEGs) were identified from YDMG versus HNDG, HG versus HNDG, and YDMG versus HG, respectively. Functional enrichment analysis suggested that signaling pathways involved in fatty acid, retinol, steroid metabolisms, and GO items related to the physical properties of the skin (e.g., collagen-containing extracellular matrix) are significantly overrepresented in DEGs identified from meat versus dairy goats. Furthermore, 106 DEGs (e.g., COL1A1, COL1A2, and SPARC) showed specific expression patterns in HG and YDMG versus HNDG. Items about biophysical features of skin (e.g., extracellular matrix organization and ECM proteoglycans) are markedly enriched. Protein-protein interaction analysis suggested that two growth factors (IGF1 and PDGFD) are latent collagen and other ECM protein expression modulators.

Conclusion: Ultrastructural analysis of goat skin tissues suggested that collagen fibril diameter is not a major factor affecting goatskin quality. Transcriptomic profiles unveiled core genes and associated biological processes potentially involved in regulating goatskin quality. These discoveries shined new light on deeper understanding the mechanisms of hide-related traits in goat and other livestock.