Polymorphisms in the promoter of interleukin-12β2 and interleukin-23 receptor genes influence milk production traits in Chinese Holstein cows

• One new SNP(c.-246G>T) in the promoter of IL-12Rβ2 gene was identified.
• The potential TFBS were analyzed for the promoter of IL-12Rβ2 and IL-23R genes.
• The IL-23Rc.-856A>G and IL-23Rc.-207T>C showed close LD (r2=0.89).
• No association was found between 3 SNPs and SCS.

SummaryInterleukin-12 (IL-12) and interleukin-23 (IL-23) are proinflammatory cytokines produced by macrophages and dendritic cells in response to infection with intracellular pathogens. Given the importance of IL-12 and IL-23 for modulating inflammation and the host immune response, the IL-12 and IL-23 receptor genes may be suitable candidate genes for studying disease resistance in dairy cattle. Twenty Chinese Holstein cows were selected randomly for PCR amplification and sequencing, and used for SNP discovery in the bovine IL-12Rβ2 and IL-23R promoter region. One SNP(c.-246G>T) in IL-12Rβ2 gene and 2 SNPs(c.-856A>G and c.-207T>C) in IL-23R gene were identified. Chinese Holstein cows (n=866) were then genotyped using Sequenom MassARRAY (Sequenom Inc., San Diego, CA) based on the 3 identified SNPs, and the associations between SNPs or haplotype of the genes and milk production traits, SCS were analyzed by the least squares method in the GLM procedure of SAS. The IL-23Rc.-856A>G and IL-23Rc.-207T>C showed close linkage disequilibrium (r2=0.89). No association was found with SCS, but associations were found between 3 of these SNP with milk protein content and lactose content. The software MatInspector revealed that these SNPs were located within several potential transcription factor binding sites, and may alter gene expression, but further investigation will be required to elucidate the biological and practical relevance of these SNP.