Identification of target genes for adenohypophysis-prefer miR-7 and miR-375 in cattle.

In this study, expression levels of miRNAs (miRNAs), miR-375 and miR-7, were detected in different tissues of cattle to determine whether adenohypophysis-prefer or exclusively expressed miRNAs, and target genes could be predicted by TargetScan, RNA22, and other software. Target genes related to pituitary function or reproductive traits were identified using a dual-luciferase assay. miR-375 and miR-7 were expressed differently in various tissues. miR-375 and miR-7 showed higher expression in the adenohypophysis, and there was a significant difference compared with expression in other tissues (P < 0.01). The binding sites for miR-7 were the mRNAs of bone morphogenetic protein receptor type II (BMPR2), prostaglandin F2 receptor negative regulator, gonadotropin-releasing hormone receptor, follicle-stimulating hormoneß, somatostatin receptor 1, and interleukin-1ß by bioinformatic analysis; similarly, the mRNAs of BMPR2 and leptin contained binding sites for miR-375, suggesting that these genes are affected by miR-7 or miR-375. Dual-luciferase reporter assays showed that miR-7 regulated prostaglandin F2 receptor negative regulator expression, while miR-375 regulated BMPR2 expression. The mutated plasmid and miRNA mimics were used to co-transfect NIH3T3 cells; luciferase reporter assays showed that the inhibition of luciferase activity in the wild-type cells dramatically decreased from 75 to 26% with a 3-5-nucleotide mismatch mutation into the seed region of miR-7. miR-375 had nearly lost the ability to inhibit luciferase activity, suggesting that GTCTTCC is the site of interaction between miR-7 and the prostaglandin F2 receptor negative regulator sequence and that GAACAAA is the site of interaction between miR-375 and the BMPR2 sequence.

WY14643 combined with all-trans retinoic acid acts via p38 MAPK to induce "browning" of white adipocytes in mice.

The ability of mammals to resist body fat accumulation is linked to their ability to expand the number of "brown adipocytes" within white fat depots. All-trans retinoic acid (t-RA) and peroxi-some proliferator-activated receptor-α (PPARα) have been implicated in "browning-like" or "browning" programs, respectively. However, a PPARα-agonist (WY14643) failed to regulate the expression of the uncoupling protein 1(UCP1) gene unless combined with retinoic acid. This study investigated the effects of the PPARα-agonist WY14643 combined with t-RA, on the "browning" of white adipocytes in mice mediated by UCP1, and the molecular mechanisms involved in this process. We compared the effects of WY14643 alone and WY14643 combined with t-RA or the p38 MAPK-inhibitor, SB203580, on white adipocytes after 24 h using the expression of UCP1, detected with RT-PCR and western blot. We also determined the mechanism by which p38 MAPK and phospho-p38 MAPK influence the process of "brown-ing" using western blot. All concentrations of WY14643 failed to in-duce UCP1 mRNA expression, protein expression, or phosphorylation of p38 MAPK (P < 0.05). WY14643 combined with t-RA was observed to induce UCP1 mRNA expression, protein expression, and phosphory-lation of p38 MAPK (P < 0.05). SB203580 combined with WY14643 and t-RA suppressed UCP1 mRNA expression, protein expression, and p38 MAPK phosphorylation (P < 0.05). WY14643 combined with t-RA can induce the transformation of white adipocytes to brown adipocytes through activation of the p38 MAPK signaling pathway.

Detection of differentially expressed genes in the longissimus dorsi of Northeastern Indigenous and Large White pigs.

Recent attention in pig breeding programs has focused on the improvement of pork quality in response to increasing consumer demands. Compared to the fatty-type Northeastern Indigenous (Chinese) breed of pigs, the lean-type Large White has lower intramuscular fat and inferior eating quality from the perspective of the Chinese consumer. In order to investigate the molecular basis of differences in pork quality in Chinese indigenous and Western breeds, longissimus dorsi samples were collected from three adult Northeastern Indigenous and three adult Large White pigs. The RNAs were extracted and hybridized to the porcine Affymetrix GeneChip. Microarray analysis demonstrated differential expression of 1134 genes of which 401 have a known function. One hundred and thirty-six genes were up-regulated and 998 down-regulated in Northeastern Indigenous breed compared to Large White pigs. We screened 10 genes as candidate genes associated with pork quality. We investigated a single nucleotide polymorphism in the 5' regulatory region of the gene FABP4 in 65 Songliao black swine, using PCR-single-strand conformational polymorphism. We found this polymorphism to be highly significantly associated with marbling and intra-muscular fat content (P ≤ 0.01). Genotype BB had higher marbling than AB and AA, but there was no significant difference between AB and AA. Genotype BB and AB had higher intra-muscular fat content than AA, but there was no significant difference between BB and AB. These results help to elucidate the genetic mechanisms behind differences in pork quality and provide a theoretical basis for selection and genetic improvement of meat quality traits in pigs.