Identification And Function Of MiRNA Related To Intramuscular Fat Deposition In Pectoral Of Gushi Chicken

MiRNA is known to be involved in the regulation of intramuscular fat deposition in chicken.Chicken is an important source of meat in our country,the miRNA expression profiles related to intramuscular fat deposition and the regulation of miRNA interplay are still scarce.Therefore,in order to fully understand the regulatory function of miRNA in the chicken muscle fat deposition process,this study analyzed the fat deposition rules of the pectoralis muscle in 6,14,22 and 30 weeks of Guoshi chicken from Chinese local varieties,constructed four development stages of pectoralis small RNA library.The expression profiles of miRNAs in four developmental stages were detected by Illumina Sequencing technique,The miRNAs related to intramuscular fat deposition was identified,The expression and potential function of these miRNA are analyzed and predicted in a comprehensive way,the functional validation of two key miRNA(miR-15 a,miR-124a-3p)was performed at the cell level.The results are as follows:1.The regularity of IMF deposition in the pectoral of Gushi chicken was negatively correlated with the growth of muscle fiber diameter,which characteristic is consistent with its growth characteristics.The synthesis of Intramuscular fat in the pectoralis was slower in the early stage of the development of chicken,while the later synthesis rate was faster,the high fat content in the early development of the pectoral mainly comes from the transport of fat in the yolk.2.A total of 388 known miRNAs and 31 new miRNAs were identified by miRNA sequencing data from the four developmental stages of the pectoral,including 92 different expressions miRNAs.There were 260 miRNAs belonging to 106 families,the remaining 176 miRNAs were not defined by the gene family,9 of these families exist only in chickens.The expression spectrum analysis ? differentially expressed miRNAs function enrichment analysis and miRNA-m RNA interwork network analysis indicated that the dynamic expression of miRNA was consistent with the law of intramuscular fat deposition.3.Overexpression of miR-15 a in chicken fibroblasts and the preadipocytes of Gushi chicken Pectoral can inhibit its predictive gene expression,Mi R-15 a has a direct targeting relationship with ACAA1,ACOX1 and SCP2,that can inhibit the expression of ACAA1 and ACOX1 from protein level.Overexpression of miR-15 a can promote the differentiation of preadipocytes and the formation of lipid droplets,which action may be partly accomplished through these predicted target genes.4.Chicken miR-124a-3p is a broad expression of miRNA,presents obvious tissue-specific and time-series expression,it is consistent with the functional prediction results of miR-124a-3p,this study suggests that miR-124a-3p may be involved in several biological processes in the body.Mi R-124a-3p can directly target the ACAA2 gene in the major lipid metabolism and fat deposition tissue,witch indicates that miR-124a-3p may be an important regulatory gene for fat deposition in the pectoral.