Preliminary Study On The Effect Of IFRD1 Gene On Body Fat Deposition In Pigs

There are many local livestock and poultry varieties with excellent traits distributing in China,and the offsprings obtained by crossing them with foreign breeds own the excellent parental traits which can satisfy people’s needs.Luchuan pig is a typical fatty pig while Duroc pig is an excellent lean type,meanwhile Dulu pig and Ludu pig which are reciprocal F1 generation of Luchuan pig and Duroc pig have inherited good meat quality,fast growth rate and reproductive performance,however there are still differences between Dulu pig and Ludu pig.In this research,the longissimus dominus of Dulu pig and Ludu pig was sequenced to analysis the growth and development difference on the transcriptional level,moerover the target gene IFRD1 was screened for expression profiling,cloning,bioinformatics analysis,and the correlation with fat deposition,furthermore in order to provide a theoretical basis to cultivate more excellent breeds.The main research results are as follows:1.The transcriptome found out 857 differential genes in the longissimus dorsi of two-month-old Dulu pig and Ludu pig.Further analysis results revealed those differential genes most enriched in two molecular functional ontology and four biological process ontology,which contained negative regulation of protein kinase activity.The differentially expressed genes were significantly enriched in 20 KEGG pathways which concluded PI3K-Akt signaling pathway,calcium signaling pathway,arachidonic acid metabolic signaling pathway and cytochrome P450 enzyme signaling pathway.At the same time,IGF2,ANKRD1,IFRD1,UCP3,PDK4 and WFIKKN2 were selected as important candidate genes that might be responsible for the growing and developmental differences between Dulu pig and Ludu pig.2.The spatiotemporal expression profile of porcine IFRD1 gene showed consistent expression profile in the tissues of 2-month-old and 8-month-old pigs.The target gene highly expressed in the lungs,higher in subcutaneous fat and a little in the longissimus dorsi.Compared with 8-month-old pigs,the expression of IFRD1 gene was significantly lower in the subcutaneous adipose tissue of 2-month-old pigs(P<0.05).Besides the expression of IFRD1 gene in the subcutaneous adipose tissue of Dulu pigs was significantly higher than that of Ludu pigs at different ages(P<0.05).In addition the KEGG results showed that IFRD1 gene was enriched in bile secretion signaling pathway and pancreatic secretory signaling pathway which were closely related to lipid metabolism.It was speculated that IFRD1 gene was associated with fat deposition of Dulu pig and Ludu pig.3.The IFRD1 gene coding region of pig was successfully cloned in this experiment.The CDS region was 1353 bp long and encoded 451 amino acids.And the IFRD1 protein was a type of unstable hydrophilic protein in the intramembrane,but no signal peptide existed.Meanwhile the secondary structure mainly contained ca-helix and random coil,there was no N glycosylation site,but two O glycosylation sites and multiple phosphorylation sites existed.Indeed,it located in two conserved domains and mainly distr:ibuted in nucleus.4.This experiment found that the expression levels of IFRD1 gene,SREBP-lc gene and ACC1 gene in subcutaneous fat of Dulu pig were significantly higher than those in Ludu pig(P<0.05).After overexpression of IFRD1 gene,the expression levels of SREBP-1c gene and ACC1 gene were significantly increased(P<0.05).The correlation analysis between IFRD1 gene expression and apparent slaughter data revealed that IFRD1 expression was significantly positively associated with carcass weight,the fat thickness of lumbar joint,6-7 thoracic vertebrae and slaughter rate(P<0.05).Moreover,IFRD1 gene was positively correlated with the indexes of porcine fat deposition,so it might influent the expression of SREBP-1c gene and ACC1 gene to play a regulator role,but the specific mechanism still needs further verification.Overall,IFRD1 gene discovered by transcriptome may positively regulate the mRNA expression of SREBP-1c and ACC1 gene,which were related to the process of pig fat deposition.Indeed,it significantly differently expressed in subcutaneous fat of Dulu pig and Ludu pig,which may be used as molecular marker to assist the breeding for better varieties.