Identification of Novel SNPs in Bovine Insulin-like Growth Factor Binding Protein-3 (IGFBP3) Gene

Comparative Genomic Characterization of Insulin-Like Growth Factor Binding Proteins in Cattle and Buffalo

The somatotropic axis consists of genes associated with economic traits like muscle growth and carcass traits in livestock. Insulin-like growth factor binding proteins (IGFBPs) are the major proteins that play a vital role in the somatotropic axis. The present study performed a genome-wide characterization of IGFBP genes in cattle. Genomic sequences of the IGFBP gene family for different mammals (cattle, buffalo, goat, and sheep) were recovered from the NCBI database. Sequence analyses were performed to investigate cattle's genomic variations in the IGFBP gene family. Phylogenetic analysis, gene structure, motif patterns, and conserved domain analysis (CDA) of the IGFBP family revealed the evolutionarily conserved nature of the IGFBP genes in cattle and other studied species. Physicochemical properties of IGFBP proteins in cattle revealed that most of these proteins are unstable, hydrophilic, thermostable, and acidic. Comparative amino acid analysis revealed variations in all protein sequences with single indels in IGFBP3 and IGFBP6. Mutation analysis revealed only one nonsynonymous mutation D212 > E in the IGFBP6 protein of cattle. A total of 245 nuclear hormone receptor (NHRs) sites were detected, including 139 direct repeats (DR), 65 everted repeats (ER), and 41 inverted repeats (IR). Out of 133 transcription factors (TFs), 10 TFs (AHR, AHRARNT, AP4, CMYB, E47, EGR2, GATA, SP1, and SRF) had differential distribution (P value < 0.05) of putative transcriptional binding sites (TFBS) in cattle compared to buffalo. Synteny analysis revealed the conserved nature of genes between cattle and buffalo. Two gene pairs (IGFBP1/IGFBP3 and IGFBP2/IGFBP5) showed tandem duplication events in cattle and buffalo. This study highlights the functional importance of genomic variation in IGFBP genes and necessitates further investigations better to understand the role and mechanisms of IGFBPs in bovines.

Polymorphisms of the insulin-like growth factor-binding protein 3 gene (IGFBP3) in gayal (Bos frontalis)

The gene coding for insulin-like growth factor-binding protein 3 (IGFBP3) is important for regulation of growth, development and metabolism in mammals. The present investigation was conducted to study nucleotide polymorphism of the IGFBP3 in gayal (Bos frontalis) and to compare the variations with those which occur in other ruminants. A fragment of 645 base pairs of the IGFBP3 covering a part of exon 2, the complete intron 2 and exon 3 and a part of intron 3 was amplified, sequenced (n=46) and digested (n=79) with HaeIII restriction enzyme from 125 collected gayal samples. Nine single nucleotide polymorphisms (SNPs) [C14T, A122C, C137T, G144C, C155T, G213A, C279A, G334A and G460A] were identified and located in intron 2, revealing high genetic variability. The alignment of nucleotide sequences was found to be very similar to those for other bovid species. Sequencing and HaeIII digestion showed that frequency of alleles C and A [consisting of fragments of sizes 56, 64, 228, 264, 282, 298 and 497 bp (CC genotype)] was 0.96 and 0.04 for the SNP C279A. Moreover, the genotype frequency of the SNP C279A in gayal was compared with that in other ruminants and it appears that this polymorphism may be associated with low fat content and rapid growth in this rare species.