Exploration of targets regulated by miR-125b in porcine adipocytes

MicroRNA (miRNA) has been proved to play a key role in lipid metabolism. In our previous study, miR-125b was validated to be differentially expressed in preadipocytes and adipocytes, which was also proved to involve in lipid metabolism. To explore the comprehensive targets of miR-125b in adipocytes, isobaric tag for relative and absolute quantitation (iTRAQ) analysis was performed to obtain differentially expressed proteins in adipocytes comparing negative control (NC) and miR-125b mimic, combining with digital gene expression (DGE) profiling of mRNA incorporated into RNA-induced silencing complex (RISC) pulled down by biotinylated miR-125b mimic and targets prediction of miR-125b by three algorithms, acyl-CoA dehydrogenase short chain (ACADS) and mitochondrial trans-2-enoyl-CoA reductase (MECR) were screened out as miR-125b direct targets. Luciferase reporter assay further validated that miR-125b mimic significantly inhibited the luciferase activity by targeting wild type (WT) 3'-UTR compared with NC. qPCR analysis of ACADS and MECR mRNA from adipose tissues of miR-125b knockout (KO) mice further confirmed the inhibition of miR-125b on ACADS and MECR expressions. Here we report miR-125b play a vital role in maintaining homeostasis of fatty acid metabolism by targeting key enzyme ACADS and MECR in the process of fatty acid elongation and degradation.

Proteomics analysis of preadipocytes between fat and lean broilers

1. Reducing excessive chicken body fat deposition is a main goal of the poultry industry. Preadipocytes are important in adipose tissue growth and development. 2. To discover proteins related to chicken fat deposition, two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) was used to identify differentially expressed proteins in preadipocytes derived from Northeast Agricultural University broiler lines divergently selected for abdominal fat content (NEAUHLF). 3. A total of 46 differentially expressed protein spots were found in the preadipocytes between fat and lean broilers. Matrix-assisted laser desorption-ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) analysis showed the protein spots corresponded to 33 different proteins. The proteins were mainly related to biological oxidation, cell proliferation, cytoskeleton, lipid metabolism, molecular chaperone, protein synthesis and signal transduction. 4. From the perspective of protein expression, these results lay a foundation for further study of the genetic mechanism of broiler adipose tissue growth and development.

Changes in adipose cells of Longissimus dorsi muscle in Iberian pigs raised under extensive conditions

Twenty-four Iberian castrated male pigs were used to characterize and evaluate the effect of the duration of "Montanera" in the adipocytes size and its relation with the backfat thickness and intramuscular fat. The animals were fed under extensive conditions during 30, 60 and 90 days in the "Dehesa" before slaughtered. Carcass weight, percentage of intramuscular fat, thickness of backfat and its three layers and adipocytes size of the intramuscular fat were obtained. The group which expended 90 days on fattening obtained the highest adipocytes, with an area higher by a 50% than those that only expended 30 days. The differences in diameter and perimeter adipocyte were not as marked as area. A significant positive correlation between the diameter, area and perimeter of adipocyte with the backfat thickness were found. The fat cells in Iberian pig hypertrophy during the "montanera stage", being this increase significant from month to month in this period of fattening. Also, this adipocyte increase is correlated with the animal weight. The correlation between adipocyte size and inner layer of backfat shows that the inner layer obtained in live pig by ultrasound techniques could be a good marker of fat infiltration in pigs fattening in "montanera" system.

Influence of Delipation on the Energy Metabolism in Pig Parthenogenetically Activated Embryos

This study was designed not only to measure the effect of delipation on the developmental viability of pig parthenogenetically activated (PA) embryos, but also to evaluate the changes of mitochondria DNA (mtDNA), reactive oxygen species (ROS) level, adenosine triphosphate (ATP) content and gene (Acsl3, Acadsb, Acaa2, Glut1) expression level at different stages after delipation. Results showed that no effect was observed on the cleavage ability, but significant lower blastocyst rate was obtained in delipated embryos. Copy number of mtDNA decreased gradually from MII to four-cell stages and subsequently kept consistent with blastocyst stage both in delipated and control embryos, but the copy number of mtDNA in delipated embryos was similar to that in the control groups no matter at which developmental stage was observed. Both in delipated and control embryos, ATP content progressive decreased from one-cell to blastocyst stages, while just at one-cell stage, a significant decrease of ATP level was observed in delipated embryos compared with that of control. The level of ROS increased obviously after delipation at cleavage stage, but no difference was seen at blastocyst stage. Finally, the expression level of genes related to fatty acids beta-oxidation (Acadsb and Acaa2) was decreased, while the expression level of genes related to glucose metabolism (Glut 1) was upregulated after delipation. In conclusion, the reduction of lipids in pig oocytes will affect the developmental competence of pig PA embryos by disturbed energy metabolism and ROS stress.

Gene Expression Patterns Associated with Peroxisome Proliferator-activated Receptor (PPAR) Signaling in the Longissimus dorsi of Hanwoo (Korean Cattle)

Adipose tissue deposited within muscle fibers, known as intramuscular fat (IMF or marbling), is a major determinant of meat quality and thereby affects its economic value. The biological mechanisms that determine IMF content are therefore of interest. In this study, 48 genes involved in the bovine peroxisome proliferator-activated receptor signaling pathway, which is involved in lipid metabolism, were investigated to identify candidate genes associated with IMF in the longissimus dorsi of Hanwoo (Korean cattle). Ten genes, retinoid X receptor alpha, peroxisome proliferator-activated receptor gamma (PPARG), phospholipid transfer protein, stearoyl-CoA desaturase, nuclear receptor subfamily 1 group H member 3, fatty acid binding protein 3 (FABP3), carnitine palmitoyltransferase II, acyl-Coenzyme A dehydrogenase long chain (ACADL), acyl-Coenzyme A oxidase 2 branched chain, and fatty acid binding protein 4, showed significant effects with regard to IMF and were differentially expressed between the low- and high-marbled groups (p<0.05). Analysis of the gene co-expression network based on Pearson’s correlation coefficients identified 10 up-regulated genes in the high-marbled group that formed a major cluster. Among these genes, the PPARG-FABP4 gene pair exhibited the strongest correlation in the network. Glycerol kinase was found to play a role in mediating activation of the differentially expressed genes. We categorized the 10 significantly differentially expressed genes into the corresponding downstream pathways and investigated the direct interactive relationships among these genes. We suggest that fatty acid oxidation is the major downstream pathway affecting IMF content. The PPARG/RXRA complex triggers activation of target genes involved in fatty acid oxidation resulting in increased triglyceride formation by ATP production. Our findings highlight candidate genes associated with the IMF content of the loin muscle of Korean cattle and provide insight into the biological mechanisms that determine adipose deposition within muscle.