title: Two Mutations in the Caprine MTHFR 3'UTR Regulated by MicroRNAs Are Associated with Milk Production Traits.
abstract: BACKGROUND
  5,10-Methylenetetrahydrofolate reductase (MTHFR) plays a central role in folate metabolism by irreversibly converting 5,10-methylenetetrahydrofolate to 5-methylenetetrahydrofolate, a predominant circulating form of folate. Folate is reportedly important for milk protein synthesis, and MTHFR may be a key regulatory point of folate metabolism for milk protein synthesis in mammary epithelial cells. Prior to this study, polymorphisms of the MTHFR gene were not associated with milk production traits from a breeding perspective. Single nucleotide polymorphisms (SNPs) at microRNA (miRNA) binding sites (miR-SNPs) can affect gene expression. This study aimed to identify the effects of miR-SNPs (g.2244A>G and g.2264A>G) in the caprine MTHFR 3' UTR on the milk production traits of dairy goats.
  
  
  RESULTS
  Guanzhong dairy (GD, n = 325) goats were used to detect SNPs in the caprine MTHFR 3' UTR by DNA sequencing. Two novel SNPs (g.2244A>G and g.2264A>G) were identified in the said region. The homozygous haplotype A-G of the SNPs g.2244A>G and g.2264A>G was significantly associated with milk yield and milk protein levels in GD goats (P < 0.05). Functional assays indicated that the MTHFR 2244 A → G substitution could increase the binding activity of hsa-miR-1266 with the MTHFR 3' UTR. The MTHFR 2264 A → G substitution could decrease the binding activity of hsa-miR-616 with the MTHFR 3' UTR. In addition, we observed a significant increase in the MTHFR mRNA levels of homozygous haplotype A-G carriers relative to those of homozygous haplotype G-A carriers. These results indicated that both SNPs altered the MTHFR mRNA levels. These altered levels of MTHFR mRNA may account for the association of SNPs with milk production traits.
  
  
  CONCLUSIONS
  This study is the first to report that the g.2244A>G and g.2264A>G polymorphisms were associated with milk production traits in GD goats. Further investigations should explore the underlying miRNA-mediated mechanisms that are modified by the g.2244A>G and g.2264A>G SNPs. The current study evaluated these SNPs as potential genetic markers in goats, with potential applications in breeding programs.
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
authors.forename: Jinxing
authors.initials: J
authors.lastname: Hou
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: An
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
authors.forename: Yuxuan
authors.initials: Y
authors.lastname: Song
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
authors.forename: Teyang
authors.initials: T
authors.lastname: Gao
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
authors.forename: Yingnan
authors.initials: Y
authors.lastname: Lei
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, P.R. China.
authors.forename: Binyun
authors.initials: B
authors.lastname: Cao
mesh_terms: D020413:3' Untranslated Regions; D000483:Alleles; D000818:Animals; D004252:DNA Mutational Analysis; D056726:Genetic Association Studies; D005838:Genotype; D006041:Goats; D006239:Haplotypes; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D035683:MicroRNAs / Q000235:genetics*; D008892:Milk; D009154:Mutation; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D019655:Quantitative Trait, Heritable; D034622:RNA Interference
chemical_list: D020413:3' Untranslated Regions; D035683:MicroRNAs; D042965:Methylenetetrahydrofolate Reductase (NADPH2)