Project description:Tail fat content affects meat quality and varies significantly among different breeds of sheep. Ghezel (fat-tailed) and Zel (thin-tailed) are two important Iranian local sheep breeds with different patterns of fat storage. The current study presents the transcriptome characterization of tail fat using RNA sequencing in order to get a better comprehension of the molecular mechanism of lipid storage in the two mentioned sheep breeds. Seven (Zel  =  4 and Ghezel  =  3) 7-month-old male lambs were used for this experiment. The results of sequencing were analyzed with bioinformatics methods, including differentially expressed genes (DEGs) identification, functional enrichment analysis, structural classification of proteins, protein-protein interaction (PPI) and network and module analyses. Some of the DEGs, such as LIPG, SAA1, SOCS3, HIF-1 α , and especially IL-6, had a close association with lipid metabolism. Furthermore, functional enrichment analysis revealed pathways associated with fat deposition, including "fatty acid metabolism", "fatty acid biosynthesis" and "HIF-1 signaling pathway". The structural classification of proteins showed that major down-regulated DEGs in the Zel (thin-tailed) breed were classified under transporter class and that most of them belonged to the solute carrier transporter (SLC) families. In addition, DEGs under the transcription factor class with an important role in lipolysis were up-regulated in the Zel (thin-tailed) breed. Also, network analysis revealed that IL-6 and JUNB were hub genes for up-regulated PPI networks, and HMGCS1, VPS35 and VPS26A were hub genes for down-regulated PPI networks. Among the up-regulated DEGs, the IL-6 gene seems to play an important role in lipolysis of tail fat in thin-tailed sheep breeds via various pathways such as tumor necrosis factor (TNF) signaling and mitogen-activated protein kinase (MAPK) signaling pathways. Due to the probable role of the IL-6 gene in fat lipolysis and also due to the strong interaction of IL-6 with the other up-regulated DEGs, it seems that IL-6 accelerates the degradation of lipids in tail fat cells.

Project description:BACKGROUND:The level of fat deposition in carcass is a crucial factor influencing meat quality. Guangling Large-Tailed (GLT) and Small-Tailed Han (STH) sheep are important local Chinese fat-tailed breeds that show distinct patterns of fat depots. To gain a better understanding of fat deposition, transcriptome profiles were determined by RNA-sequencing of perirenal, subcutaneous, and tail fat tissues from both the sheep breeds. The common highly expressed genes (co-genes) in all the six tissues, and the genes that were differentially expressed (DE genes) between these two breeds in the corresponding tissues were analyzed. RESULTS:Approximately 47 million clean reads were obtained for each sample, and a total of 17,267 genes were annotated. Of the 47 highly expressed co-genes, FABP4, ADIPOQ, FABP5, and CD36 were the four most highly transcribed genes among all the known genes related to adipose deposition. FHC, FHC-pseudogene, and ZC3H10 were also highly expressed genes and could, thus, have roles in fat deposition. A total of 2091, 4233, and 4131 DE genes were identified in the perirenal, subcutaneous, and tail fat tissues between the GLT and STH breeds, respectively. Gene Ontology (GO) analysis showed that some DE genes were associated with adipose metabolism. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that PPAR signaling pathway and ECM-receptor interaction were specifically enriched. Four genes, namely LOC101102230, PLTP, C1QTNF7, and OLR1 were up-regulated and two genes, SCD and UCP-1, were down-regulated in all the tested tissues of STH. Among the genes involved in ECM-receptor interaction, the genes encoding collagens, laminins, and integrins were quite different depending on the depots or the breeds. In STH, genes such as LAMB3, RELN, TNXB, and ITGA8, were identified to be up regulated and LAMB4 was observed to be down regulated. CONCLUSIONS:This study unravels the complex transcriptome profiles in sheep fat tissues, highlighting the candidate genes involved in fat deposition. Further studies are needed to investigate the roles of the candidate genes in fat deposition and in determining the meat quality of sheep.

Project description:An essential tissue involved in the development and regulation of lipid metabolism in animals is adipose tissue. The “fat-tail” can supply energy for sheep during migration and winter when a low amount of dry matter intake is available. Tail fat content affects meat quality and varies significantly among the different breeds of sheep. Ghezel (fat-tailed) and Zel (thin-tailed) are two important local Iranian sheep breeds that show different patterns of fat storage. The current study presents the transcriptome characterization of tail fat using RNA-sequencing in order to get a better comprehension of the molecular mechanism of lipid storage in the two sheep breeds. The results of sequencing were analyzed with bioinformatics methods, including differentially expressed genes (DEGs) identification, functional enrichment analysis, structural classification of proteins, protein–protein interaction (PPI), network analysis and module analysis. The results revealed a total of332 DEGs between the Zel and Ghezel breed, with78 up-regulated and 254 down-regulated DEGs in the Zel breed. Identification of differential genes showed that some DEGs, such as IL-6, LIPG, SAA1, SOCS3 and HIF-1α, with the largest fold change had close association with lipid deposition. Also, important lipid storage genes such as FASN and SCPEP1 had high levels of expression. Furthermore, functional enrichment analysis revealed some pathways associated with fat deposition, such as “Fatty acid metabolism”, “Fatty acid biosynthesis” and“HIF-1 signaling pathway”. In addition, structural classification of proteins showed major DEGs in transcription factor classes such as JUNB, NR4A3, FOSL1, MAFF, NR4A1, CREB3L1 and ATF3 were up-regulated in the Zel breed. IL-6, JUNB, and related DEGs were up-regulated in the PPI network.HMGCS1, SUCLA2 and STT3B and related DEGs were down-regulated in the PPI network and had high topology scores as hub genes. This implies the DEGs of these modules are important candidate genes for tail fat metabolism and, therefore, can be further studied.

Project description:Lipins play dual function in lipid metabolism by serving as phosphatidate phosphatase and transcriptional co-regulators of gene expression. Mammalian lipin proteins consist of lipin1, lipin2, and lipin3 and are encoded by their respective genes Lpin1, Lpin2, and Lpin3. To date, most studies are concerned with Lpin1, only a few have addressed Lpin2 and Lpin3. Ontogenetic expression of Lpin2 and Lpin3 and their associations with traits would help to explore their molecular and physiological functions in sheep. In this study, 48 animals with an equal number of males and females each for both breeds of fat-tailed sheep such as Guangling Large Tailed (GLT) and Small Tailed Han (STH) were chosen to evaluate the ontogenetic expression of Lpin2 and Lpin3 from eight different tissues and months of age by quantitative real-time polymerase chain reaction (PCR). Associations between gene expression and slaughter and tail traits were also analyzed. The results showed that Lpin2 mRNA was highly expressed in perirenal and tail fats, and was also substantially expressed in liver, kidney, reproductive organs (testis and ovary), with the lowest levels in small intestine and femoral biceps. Lpin3 mRNA was prominently expressed in liver and small intestine, and was also expressed at high levels in kidney, perirenal and tail fats as well as reproductive organs (testis and ovary), with the lowest level in femoral biceps. Global expression of Lpin2 and Lpin3 in GLT both were significantly higher than those in STH. Spatiotemporal expression showed that the highest levels of Lpin2 expression occurred at 10 months of age in two breeds of sheep, with the lowest expression at 2 months of age in STH and at 8 months of age in GLT. The greatest levels of Lpin3 expression occurred at 4 months of age in STH and at 10 months of age in GLT, with the lowest expression at 12 months of age in STH and at 8 months of age in GLT. Breed and age significantly influenced the tissue expression patterns of Lpin2 and Lpin3, respectively, and sex significantly influenced the spatiotemporal expression patterns of Lpin3. Meanwhile, Lpin2 and Lpin3 mRNA expression both showed significant correlations with slaughter and tail traits, and the associations appear to be related with the ontogenetic expression as well as the potential functions of lipin2 and lipin3 in sheep.

Project description:The fat tail is a phenotype that divides indigenous Iranian sheep genetic resources into two major groups. The objective of the present study is to refine the map location of candidate regions associated with fat deposition, obtained via two separate whole genome scans contrasting thin and fat tail breeds, and to determine the nature of the selection occurring in these regions using a hitchhiking approach. Zel (thin tail) and Lori-Bakhtiari (fat tail) breed samples that had previously been run on the Illumina Ovine 50 k BeadChip, were genotyped with a denser set of SNPs in the three candidate regions using a Sequenom Mass ARRAY platform. Statistical tests were then performed using different and complementary methods based on either site frequency (FST and Median homozygosity) or haplotype (iHS and XP-EHH). The results from candidate regions on chromosome 5 and X revealed clear evidence of selection with the derived haplotypes that was consistent with selection to near fixation for the haplotypes affecting fat tail size in the fat tail breed. An analysis of the candidate region on chromosome 7 indicated that selection differentiated the beneficial alleles between breeds and homozygosity has increased in the thin tail breed which also had the ancestral haplotype. These results enabled us to confirm the signature of selection in these regions and refine the critical intervals from 113 kb, 201 kb, and 2831 kb to 28 kb, 142 kb, and 1006 kb on chromosome 5, 7, and X respectively. These regions contain several genes associated with fat metabolism or developmental processes consisting of TCF7 and PPP2CA (OAR5), PTGDR and NID2 (OAR7), AR, EBP, CACNA1F, HSD17B10,SLC35A2, BMP15, WDR13, and RBM3 (OAR X), and each of which could potentially be the actual target of selection. The study of core haplotypes alleles in our regions of interest also supported the hypothesis that the first domesticated sheep were thin tailed, and that fat tail animals were developed later. Overall, our results provide a comprehensive assessment of how and where selection has affected the patterns of variation in candidate regions associated with fat deposition in thin and fat tail sheep breeds.

Project description:An essential tissue involved in the development and regulation of lipid metabolism in animals is adipose tissue. The “fat-tail” can supply energy for sheep during migration and winter when a low amount of dry matter intake is available. Tail fat content affects meat quality and varies significantly among the different breeds of sheep. Ghezel (fat-tailed) and Zel (thin-tailed) are two important local Iranian sheep breeds that show different patterns of fat storage. The current study presents the transcriptome characterization of tail fat using RNA-sequencing in order to get a better comprehension of the molecular mechanism of lipid storage in the two sheep breeds. The results of sequencing were analyzed with bioinformatics methods, including differentially expressed genes (DEGs) identification, functional enrichment analysis, structural classification of proteins, protein–protein interaction (PPI), network analysis and module analysis. The results revealed a total of332 DEGs between the Zel and Ghezel breed, with78 up-regulated and 254 down-regulated DEGs in the Zel breed. Identification of differential genes showed that some DEGs, such as IL-6, LIPG, SAA1, SOCS3 and HIF-1α, with the largest fold change had close association with lipid deposition. Also, important lipid storage genes such as FASN and SCPEP1 had high levels of expression. Furthermore, functional enrichment analysis revealed some pathways associated with fat deposition, such as “Fatty acid metabolism”, “Fatty acid biosynthesis” and“HIF-1 signaling pathway”. In addition, structural classification of proteins showed major DEGs in transcription factor classes such as JUNB, NR4A3, FOSL1, MAFF, NR4A1, CREB3L1 and ATF3 were up-regulated in the Zel breed. IL-6, JUNB, and related DEGs were up-regulated in the PPI network.HMGCS1, SUCLA2 and STT3B and related DEGs were down-regulated in the PPI network and had high topology scores as hub genes. This implies the DEGs of these modules are important candidate genes for tail fat metabolism and, therefore, can be further studied.

Dataset Information

Regulatory Roles of SREBF1 and SREBF2 in Lipid Metabolism and Deposition in Two Chinese Representative Fat-Tailed Sheep Breeds.

Publications

Regulatory Roles of <i>SREBF1</i> and <i>SREBF2</i> in Lipid Metabolism and Deposition in Two Chinese Representative Fat-Tailed Sheep Breeds.

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