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Detection of functional polymorphisms influencing the promoter activity of the SAA 2 gene and their association with milk production traits in Chinese Holstein cows
Author(s) -
Yang S.,
Li C.,
Xie Y.,
Cui X.,
Li X.,
Wei J.,
Zhang Y.,
Yu Y.,
Wang Y.,
Zhang S.,
Zhang Q.,
Sun D.
Publication year - 2015
Publication title -
animal genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 81
eISSN - 1365-2052
pISSN - 0268-9146
DOI - 10.1111/age.12332
Subject(s) - biology , milk production , gene , genetics , holstein cattle , association (psychology) , dairy cattle , genetic association , single nucleotide polymorphism , zoology , genotype , philosophy , epistemology
Summary Our previous RNA sequencing experiment showed that the serum amyloid A2 ( SAA 2 ) gene was one of the most promising candidates for milk protein and fat traits in dairy cattle. The SAA 2 gene encodes an apolipoprotein related to high‐density lipoproteins. To further validate its genetic effects, genotype–phenotype associations were performed in this study. Through resequencing of the entire coding region and the 5’‐regulatory region of the SAA 2 gene using pooled DNA of 12 unrelated sires, one novel 3‐bp insertion–deletion and five previously reported SNP s were detected. These identified SNP s were genotyped and tested for association with five milk production‐related traits in 717 Chinese Holstein cows. After Bonferroni correction for multiple t ‐tests, five of them were found to be statistically significant for milk yield, fat yield and protein yield ( P < 0.0001~0.0053). Haplotype‐based association analysis revealed a similar effect on fat yield and protein yield ( P = 0.0005, P = 0.0032 respectively). Then, using luciferase report assay, the regulatory effect of the three SNP s located in the promoter region (c.‐22G>A; c.17G>C; c.114G>A) was evaluated on transcriptional activity. In HEK ‐293 cell lines, we found that constructs GCG and AGG showed higher luciferase activity compared with GCA ( P < 0.01, P < 0.01 respectively). Meanwhile, the prediction of the putative differential transcription factor binding site revealed that c.17G>C and c.114G>A caused the alteration in the transcription factor. Overall, the findings presented here provide the first evidence for associations of the SAA 2 gene with milk fat and protein traits, which appears to be a key candidate for milk production traits in dairy cattle.