Genetic variations in the sheep SIRT7 gene and their correlation with body size traits

Abstract

As a nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylase and ADP ribosyl transferase, the silent information regulator 7 (Sirtuin 7, SIRT7) plays a crucial role in regulating the differentiation of adipocytes and myoblasts, lipid metabolism, glucose metabolism, and cellular growth in mammals. It has been hypothesized that SIRT7 affects growth traits in animals; therefore, in this study, the potential insertion/deletion (indel) of genetic variations within the ovine SIRT7 gene and their correlation with sheep growth traits were explored. A total of 709 individuals from five Chinese and Mongolian sheep breeds were analyzed. Two novel indel loci of the sheep SIRT7 gene were detected and were named 5 ${}^{\text{'}}$ promoter region-insertion-7 bp (5 ${}^{\text{'}}$ promoter region-7 bp) and 3 ${}^{\text{'}}$ UTR-insertion-17 bp (3 ${}^{\text{'}}$ UTR-17 bp), respectively. In all of the sheep breeds, frequencies of the 5 ${}^{\text{'}}$ promoter region-7 bp mutation were low, whereas mutations of 3 ${}^{\text{'}}$ UTR-17 bp were high in Tong sheep and Lanzhou fat-tail sheep (LFTS). Furthermore, both indel polymorphisms had significant associations with different growth characteristics ( $P<0.05$ ). Among these associations, the 3 ${}^{\text{'}}$ UTR-17 bp was highly correlated with rump width in small-tail Han sheep (STHS, rams; $P<0.01$ ), and individuals with the ID genotype had better chest depth values than those with the II genotype. In this paper, two novel indels within the sheep SIRT7 gene were identified, and genetic diversity and its effects on body size traits were explored. These findings will potentially provide useful DNA markers for the improvement of economic traits in sheep genetic breeding.

Figure 1

Electrophoresis diagram and sequence of 3${}^{\prime }$ UTR-insertion-17 bp loci and 5${}^{\prime }$ promoter region-insertion-7 bp within the ovine SIRT7 gene.

Figure 2

Linkage equilibrium test of two pairs of alleles within the ovine SIRT7 gene in different populations: (a) Lanzhou fat-tail sheep, (b) small-tail Han sheep, (c) Tong sheep, (d) Hu sheep, and (e) Sartuul sheep. Note: the 5${}^{\prime }$ promoter region-insertion-7 bp (loci1) and 3${}^{\prime }$ UTR-insertion-17 bp loci (loci2) were chosen for haplotype analysis.

Figure 3

Haplotype frequency of the 5${}^{\prime }$ promoter region-insertion-7 bp and 3${}^{\prime }$ UTR-insertion-17 bp loci of the ovine SIRT7 gene in different breeds. Note: LFTS – Lanzhou fat-tail sheep; STHS – small-tail Han sheep; TS – Tong sheep; HS – Hu sheep; and SS – Sartuul sheep.