Relationship Of IGFBPs And LOC106047490 With Productive Performance In The Geese With Fatty Liver

Goose fatty liver is not only an important waterfowl product,but also a unique model for study of non-alcoholic fatty liver.Identifying key candidate genes and uncovering their roles in the development of goose fatty liver may help address the underlying mechanism and promote a marker-assisted selection for fatty liver-producing geese.If the expression or nucleic acid polymorphism(such as SNP)of a gene is associated with productive performance in the geese with fatty liver,the gene could be used as a marker in goose selection,thus improving selection efficiency and overcoming the current problem in the breeding of liver-specific goose.In this study,the expression of the IGFBP family genes and a long noncoding RNA gene(LOC106047490)was determined,and the association of SNP loci in the genes with the productive performance in the geese with fatty liver was also analyzed.The details of the methods and results are as follows:1.RT-qPCR was used to determine the expression of IGFBP family genes in the livers from geese that were overfed for 19 days or normally fed.The data showed that the expression of IGFBP1,IGFBP2 and IGFBP5 was significantly inhibited in fatty liver compared to normal liver,suggesting that these genes were closely related to the development of goose fatty liver,and their expression may be used to predict productive performance in the geese with fatty liver.2.The primers specific for IGFBP1,IGFBP2 and IGFBP5 genes and their upstream DNA region(2 kb)were designed and used in SNP identification,and the SNPs identified were then used to evaluate the association of the genes with the weights of liver,abdominal fat and carcass.The results showed that,for IGFBP1,7 SNPs were identified in Yangzhou geese,no SNPs in Landes geese,and 12 SNPs between the breeds;for IGFBP2,13 SNPsi were identified in Yangzhou geese,1 SNP in Landes geese,and 49 SNPs between the breeds.Statistical analysis indicated that the only SNP of Landes breed was significantly associated with abdominal fat weight of the overfed geese(p<0.01).For IGFBP5,10 SNPs were identified in Yangzhou geese,3 SNPs in Landes geese,and 19 SNPs between the breeds.Statistical analysis showed that two SNPs of Landes breed were significantly associated with liver weight of the overfed geese(p<0.01).These findings verified the implication of these genes in the breeding of liver-specific goose as selection markers from the point of association analysis.3.By PCR with gene-specific primers,this study determined the sequence at the site of 1602 bp upstream of goose IGFBP2 gene,which is unknown in the NCBI database.The sequence is 367 bp long.4.The expression of a long noncoding RNA(lncRNA)gene(LOC106047490)in the liver,abdominal fat and breast muscle was determined by.RT-qPCR in the geese overfed for 7,14 and 19 days or the geese that normally fed.The results showed that overfeeding led to a decrease in the expression of the lncRNA gene in all the tissues,and the decrease of the expression in the liver and muscle was more dramatic along with extension of overfeeding time.The findings suggest that the expression of this lncRNA gene may be used to predict the amount of fat deposited in the tissues of geese with fatty liver.5.To understand the relationship between the lncRNA and the development of goose fatty liver,goose primary hepatocytes were treated with fatty liver-related factors(high level of glucose,insulin,palmitic acid,oleic acid and linoleic acid),followed by RT-qPCR analysis.The results showed that,except for the palmitate,the factors could induce the expression of the gene,and the induction was varied with the dosages of the factors.This induction is inconsistent with the suppression of expression in goose liver,suggesting that other factors play more important role in regulating the expression of the gene.6.To learn about the tissue-specificity in the expression of the IncRNA gene,RT-qPCR was used to determine the expression of the gene in a variety of tissues of 23-day-old goose embryos and 89-day-old geese.The results showed that the expressions of the gene was low in the liver and thigh muscle while high in heart,breat muscle,intestine and gizzard in the embryos.In 89-day-old geese,the expression of the gene was the highest in abdominal fat.In addition,it was found that the expression pattern of the gene was changed with the time of growth by comparing the expression of the gene in same tissues over different time.These results provide scientific information for use of the gene in marker-assisted selection of goose.7.SNP analysis was carried out with the exonic sequence of the IncRNA gene.The data showed that no SNP was identificed in Landes geese,while 12 SNPs were identified in Yangzhou geese.In summary,we found that the IGFBP family genes and long noncoding RNA gene(LOC106047490)are closely related to the development of goose fatty liver,and they are important candidate genes for marker assisted selection in the geese with fatty liver.Further exploitation of these genes will be helpful to solve the existing problems in goose breeding.