Polymorphisms Identification Of KLF7, KLF11 And KLF15 Genes And Their Associations With Cattle Growth Traits

Genes that regulate metabolism and energy partitioning have the potential to influence growth traits in farm animals, as do polymorphisms within these genes. KLFs (Kruppel-like factors) are highly conserved basic transcription element binding protein (BTEP). There are conserved zinc finger domains at their C-termini that can bind specifically to the GC-rich promoter sequences of target genes, thus activating or repressing their expression, and then regulate the proliferation and differentiation of kinds of cells as well as the development of tissues. This study was conducted to identify single nucleotide polymorphisms (SNPs) in genes encoding Kruppel-like factors family and assess the associations of polymorphisms identified with cattle growth traits. Genetic variations of energy homeostasis related genes (KLF4, KLF5, KLF7, KLF11 and KLF15) were detected by PCR-RFLP, PCR-SSCP and DNA sequencing techniques in 1045 individuals of four populations (Nanyang cattle, Qinchuan cattle, Jiaxian cattle and Chinese Holstein), and association analysis were carried out to evaluate the effects of genotypes of candidate genes on growth traits of four Chinese cattle populations. The objects were to discovery the hereditary characteristics and to explore molecular markers with significant effects on economic important traits for efficient selection and improvement of Chinese cattle, and to provide genetic information for foundation of molecular marker database, protection and usage of breed resource of Chinese cattle.In current study, 17 loci of five KLFs (KLF4, KLF5, KLF7, KLF11 and KLF15 genes) were scanned, but only 5 SNPs were found in three genes (KLF7, KLF11 and KLF15 genes), this were consisted with the highly conserved and essential functions of KLF transcriptional factors.1. Polymorphisms identification and associations of Kruppel-like factor KLF7 gene with cattle growth traitsIn the current study, three SNPs of exon 2 and its flanking region of KLF7 gene were revealed: NC₀07300:g.41401C>T (p.F54F), 42025T>C and 42075A>G. Interestingly, the three SNPs can be detected simultaneously after created restriction recognized sites. It was found all the breeds were in Hardy-Weinberg equilibrium except Chinese Holstein at C41401T locus (P > 0.05). The statistical results indicated there was a strong linkage not only between C41401T and T42025C in Jiaxian, but also between T42025C and A42075G in Qinchuan, Nanyang and Chinese Holstein respectively (r2 > 0.33). Significant statistical differences in genotypic frequencies at the three loci displayed that the polymorphisms were remarkably correlated with cattle breeds byχ2 test (P < 0.001). In addition, The cattle with genotype T2T2 (T42025C) had greater average daily gain (P = 0.009) and heart girth (P = 0.009) than those with genotype T2C2 at 6 months. The cattle with genotype C2C2 (T42025C) had greater body weight (P = 0.008), body length (P = 0.001), and heart girth (P = 0.003) than those with genotype T2C2 at 12 months. The cattle with genotype A3A3 (T42075C) had greater body length (P = 0.006) than those with genotype A3G3 at 12 months. the cattle with haplotype C1C1C2C2A3A3 (H1) had greater body length (P = 0.001) and heart girth (P = 0.004) than those with haplotype C1C1T2C2A3G3 (H2) at 12 months. The cattle with haplotype C1T1T2C2A3G3 (H5) had greater hucklebone width (P = 0.007) than those with haplotype C1C1T2C2A3G3 (H2) at 12 months.3 SNPs of KLF7 gene have no significant associations with the growth traits of Qinchuan and Jiaxian.2. Polymorphisms identification and associations of Kruppel-like factor KLF11 and KLF15 genes with cattle growth traitsIn the current study, twelve loci of KLF4, KLF5, KLF11 and KLF15 genes were scaned and two novel SNPs, NC₀07309:g.24769 C>T of bovine KLF11 gene and NC₀07301:g.1230 A>G of bovine KLF15 gene, were identified, in which a missense mutation was identified: p:I19V in KLF15 gene. The genetic diversities in analyzed populations were found not high. The distributions of genotypic frequencies of KLF11 and KLF15 loci were significantly associated with bovine breeds byχ2 test. Correlation analysis indicated that an C/T SNP located in 3'-UTR of the KLF11 gene had large effect on body weight (P = 0.002), average daily gain (P = 0.006), body length (P = 0.001) at 6 months and average daily gain (P = 0.005) at 12 months in Nanyang cattle. But the SNP in KLF15 gene did not showed associations at P < 0.05 with any examined traits. Although C/T in KLF11 do not cause amino acid changes, it could be linked to other yet to be detected causative mutations or nearby QTL.2 SNPs of KLF11 and KLF15 gene have no significant associations with the growth traits of Qinchuan and Jiaxian. 3. Expression profiles of KLF7 and KLF11 genes in 12 tissues of 18 months old Qinchuan cattle12 freezed tissues including fat in abdomen, hypophysis, small intestine, kidney, liver, muscle, heart, spleen, lung, lacteal gland, stomach, adipose layer of three Qinchuan cattle (18 months) were collected. SYBR Green I was used to detect the expression situation of KLF7 and KLF11 genes in these tissues, the results showed that the expressions of KLF7 and KLF11 were similarly abundant in stomach, adipose layer and fat in abdomen, which were major organs involving in energy metabolism. The results implied that KLF7 and KLF11 were functional important in energy metabolism.