Abstract

The insulin-like growth factor-1 (IGF-1), a key hormone in muscle development was investigated for single-nucleotide polymorphisms (SNPs) upstream of the IGF-1 gene and their effects upon its cognate mRNA and hormone levels in sheep. A 70 d feeding trial was conducted with 22 F1 (Dorper × Pelibuey) lambs, individually allocated and fed a diet with a forage-to-concentrate ratio of 36:64 and 17% crude protein. Sequence analyses of 265 bp upstream the IGF-1 gene revealed the variant NC_040254.1:g.[184028491G > C;184028493G > A]. These SNPs generate alleles A and B, with frequencies of 0.66 and 0.34 in F1 lambs and of 0.73 and 0.27 in 81 pure Dorper lambs, respectively. Females were grouped by genotype AA, AB and BB (n = 3). IGF-1 hormone concentrations at 14, 42 and 70 d were higher (p < 0.05) in AA lambs compared to AB + BB lambs. The IGF-1 mRNA level was 2.6-fold higher in AA animals (n = 5, p < 0.05) than in AB + BB lambs (n = 7). A DNA binding site for the Inhibitor of Growth family member 4 (ING4) was found in allele B but not in allele A, which could explain the lower mRNA and hormone expression levels for AB + BB animals. The variant reported here appears to function as an eQTL with a negative effect on the level of IGF-1.

摘要

研究了胰岛素样生长因子-1（IGF-1），它是肌肉发育中的关键激素，用于IGF-1基因上游的单核苷酸多态性（SNP）及其在绵羊中其同源mRNA和激素水平的影响。进行了70天的饲喂试验，对22只F1（Dorper×Pelibuey）羔羊进行了单独分配，并饲喂饲料中草料与精料的比例为36:64，粗蛋白为17％。IGF-1基因上游265 bp的序列分析揭示了变体NC_040254.1：g。[184028491G> C; 184028493G> A]。这些SNP产生等位基因A和B，在F1羔羊中的频率分别为0.66和0.34，在81只纯净的Dorper羔羊中的频率分别为0.73和0.27。女性按AA，AB和BB基因型分组（n = 3）。 与AB + BB羔羊相比，AA羔羊在14、42和70 d时IGF-1激素浓度更高（p <0.05）。与AA  + BB羔羊（n  = 7）相比，AA动物（n  = 5，p <0.05）中IGF-1 mRNA水平高2.6倍。在等位基因B中发现了生长抑制剂家族成员4（ING4）的DNA结合位点，而在等位基因A中未发现，这可以解释AB + BB动物较低的mRNA和激素表达水平。此处报道的变体似乎充当eQTL，对IGF-1的水平产生负面影响。