Genetic polymorphisms in bovine ferroportin are associated with beef iron content
Iron is an essential element for almost all living organisms. Tissue iron concentration shows natural variations among individuals, because of the influence of both environmental and genetic factors. Body iron, though essential, is also toxic in excess by generating reactive oxygen species. Iron homeostasis, thus, must be maintained systemically by the rate of iron absorption, iron utilization, iron storage and the rate of iron recycling. It is possible that mutations in any of the genes that encode proteins involved in maintaining iron homeostasis have the potential to alter iron load. The effect of single nucleotide polymorphisms (SNPs), a major genetic factor, on beef iron content were investigated in the current study.
The first objective of this study was to determine the variation of iron content in bovine longissimus dorsi (LD) muscle. The second objective was to identify single nucleotide polymorphisms (SNPs) in the exons and their flanking regions of the bovine ferroportin gene (Fpn) and to evaluate the association between the identified SNPs and bovine muscle iron content. LD muscle samples were collected from 1086 Angus cattle for iron quantification and genomic DNA extraction. Nine exons and their flanking regions of Fpn were amplified and sequenced with 6 selected DNA samples. Genotyping was carried out for 1086 cattle. Nine novel SNPs, NC007300: g.1780 A>G, g.1872 A>G, g.7169 C>T, g.7477 C>G, g.19208 C>T, g.19263 A>G, g.19427 A>G, g.19569 C>T and g.20480 C>T, were identified. Statistical analysis showed that three of the nine SNPs, g.19208 C>T, g.19263 A>G, and g.20480 C>T, were significantly (P < 0.007) associated with muscle iron content. High linkage disequilibrium was observed for SNP g.19208 C>T, g. 19263 A>G and g. 20480 C>T (R2 > 0.99), with which two haplotypes, TGC and CAT, were defined. Beef from individuals that were homozygous for the TGC haplotype had significantly (P < 0.001) higher iron contents than did beef from CAT homozygous or heterozygous individuals.
In conclusion, results of the current study indicated that SNPs, NC007300: g.19208 C>T, g.19263 A>G, and g.20480 C>T, in Fpn might be useful markers for the selection of Angus cattle that produce progeny with a more desirable iron composition and therefore improve the healthfulness of beef. Further studies are needed to verify the observed effect in other independent populations and elucidate the biological mechanisms of the SNP effects.