Detection of Genomic Selection Signatures and Identification of Beneficial Mutations for Fat Deposition in Sheep with Different Tail Types

Chinese indigenous sheep can be classified into two types based on tail morphology: fat-tailed sheep and thin-tailed sheep, with Altay sheep and Tibetan sheep as their representative breeds. Detection of selection signatures can elucidate the molecular mechanism underlying the formation of distinct tail types driven by artificial selection. Based on the Illumina Ovine 600K SNP BeadChip, we identified 163 and 267 candidate selection regions in Altay sheep and Tibetan sheep, with average lengths of 26.61 Mb and 45.68 Mb, respectively. Subsequent bioinformatics analysis suggested that LPIN1 might be involved in fat deposition. Genotyping of the candidate gene LPIN1 in 546 sheep revealed three single nucleotide polymorphisms (SNPs). At the cellular level, the C236T mutation was found to promote the proliferation and differentiation of preadipocytes. Transcriptome analysis demonstrated differential expression of PGC-1α between the CC and TT genotypes of the LPIN1 gene. Secondary structure prediction via SOPMA software indicated that the C236T mutation could alter the number of Alpha helix (Hh) and Random coil (Cc) in the secondary structure of its encoded protein. Yeast two-hybrid assays indicated that this mutation may enhance the binding between LPIN1 and PGC-1α proteins. Quantitative real-time PCR analysis of genes associated with the PPAR signaling pathway revealed concurrent alterations in the expression of these genes. Collectively, these results suggest that the LPIN1 C236T mutation may participate in tail fat deposition in sheep, and thus it can be used as a molecular marker for selective breeding of thin-tailed sheep breeds.