SNPs, MRNA Expression And Methylation Of STAT3 And STAT5A Genes And Their Influences On Production Traits In Goats

Signal transduction and transcriptional activation protein 3(STAT3) and signal transduction and transcriptional activation protein 5A(STAT5A) are the members of STAT family, which are both multifunctional transcription factors regulated a variety of cytokines and growth hormone. Moreover, their expressions are directly or indirectly regulated by related hormone genes of Pituitary- the hypothalamus- adrenal axis(HPA), e.g. growth hormone(GH). Therefore, the genetic and epigenetic changes of STAT3 and STAT5 A genes would directly or indirectly impact the production traits of goat. This study was viewed from two aspects including molecular genetics and epigenetics, mainly studied genetic variations and DNA methylation modifications of STAT3 and STAT5 A genes and their effects on production traits of Xinong Saanen dairy goat and Hainan black goat, expected to find out the functional SNPs and DNA methylation loci which would have significant influences on production traits. At the same time, this study decoded the potential impact of SNPs and DNA methylation on mRNA expression, which would provide theoretical foundation for molecular breeding of goat. 1. Cloning of goat STAT3, STAT5 A genes whole CDS regions and the prediction for protein physical and chemical properties.This study successfully cloned the CDS regions of STAT3 and STAT5 A genes by RT-PCR, PCR and TA cloning. Phylogenetic tree was constructed, and the physical and chemical properties of proteins were analyzed. Protein secondary structure and epigenetics modification sites were predicted.2. SNPs of STAT3, STAT5 A genes and their influences on production traitsThis study found out the novel SNPs of STAT3, STAT5 A genes in 707 Xinong Saanen dairy goats and Hainan black goats by DNA pool sequencing, PCR-RFLP and aRCS PCR-RFLP. Three novel SNPs(45204 C>T; 62058 A>G; 62230 C>T) were detected in STAT3 gene intron 2, 10 and 11, respectively. And three new SNPs(Tyr90Tyr; IVS1 + 254 C>T, IVS3 + 303 T>C) were detected in STAT5 A gene as well as a known SNP(Pro268Pro) in exon 7. Association analysis showed that three SNPs of STAT3 gene were significantly associated with zoometric traits of Xinong Saanen dairy goats(P<0.05). The synonymous mutation Pro268 Pro in STAT5 A gene was significantly associated with zoometric traits of Hainan black goats. These findings suggested that these 4 SNPs could be considered as the DNA markers in improving production traits through marker-assisted selection(MAS) in goats. 3. Effects of SNPs within STAT3 and STAT5 A genes on mRNA expressionThis study analyzed the expression profiles of STAT3 and STAT5 A genes, which were identified the relationship between genotypes of SNPs and mRNA expression using DNA and 9 tissues cDNA samples of Xinong Saanen dairy goats. These results showed that the genotype CC of SNP(45204 C>T) locus significantly affected mRNA expression in liver and pancreatic tissues(P<0.05). In kidney, the genotype CC of SNP(STAT5A-XhoI) locus was significantly affected mRNA expression. All the data suggested that the SNPs of STAT3 and STAT5 A genes had significant influences on mRNA expression. 4. Impact of DNA methylation of STAT3 and STAT5 A genes on production traitsUsing bisulfite treatment directly sequencing, this study explored the CpG islands methylation modification of STAT3 and STAT5 A genes and their relationships between DNA methylation loci and the goat production traits. According to the DNA samples of Xinong Saanen dairy goats and Hainan black goats and detailed production data, this study demonstrated that the methylation level of STAT3 gene promoter had significant effects on body weight in HNBG. Besides, the methylation levels of CpG-3 and CpG-5 dinucleotide loci in STAT5 A gene intron 8 CpG island had significant influences on milk yield and milk density in XNSN, respectively. In details, the whole CpG island and CpG-3, 4, 5, 6, 9, 10, 11 and 12 CpG-dinucleotide loci of STAT5 A had significant effects on body weight in HNBG. In these two breeds, the low methylation rate of STAT3 and STAT5 A genes’ CpG islands were significant associated with high performance(P<0.05). These findings demonstrated that DNA methylation might have influences on body weight, milk yield and milk density of goats, suggesting that they may become epigenetic markers to improve production traits through epigenetic marker-assisted selection(eMAS) in goats.