Cattle and buffalo served as the first and second largest
dairy
animals, respectively, providing 96% milk products worldwide. Understanding
the mechanisms underlying milk synthesis is critical to develop the
technique to improve milk production. Thiolases, also known as acetyl-coenzyme
A acetyltransferases (ACAT), are an enzyme family that plays vital
roles in lipid metabolism, including ACAT1, ACAT2, ACAA1, ACAA2, and
HADHB. Our present study showed that these five members were orthologous
in six livestock species including buffalo and cattle. Transcriptomic
data analyses derived from different lactations stages showed that ACAA1 displayed different expression patterns between buffalo
and cattle. Immunohistochemistry staining revealed that ACAA1 were
dominantly located in the mammary epithelial cells of these two dairy
animals. Knockdown of ACAA1 inhibited mammary epithelial
cell proliferation and triglyceride and β-casein secretion by
regulating related gene expressions in cattle and buffalo. In contrast, ACAA1 overexpression promoted cell proliferation and triglyceride
secretion. Finally, three novel SNPs (g.-681A>T, g.-23117C>T,
and
g.-24348G>T) were detected and showed
significant association with milk production traits of Mediterranean
buffaloes. In addition, g.-681A>T mutation located in the promoter
region changed transcriptional activity significantly. Our findings
suggested that ACAA1 play a key role in regulating
buffalo and cattle milk synthesis and provided basic information to
further understand the dairy animal lactation physiology.