FNDC5 expression closely correlates with muscle fiber types in porcine longissimus dorsi muscle and regulates myosin heavy chains (MyHCs) mRNA expression in C2C12 cells.

BACKGROUND: Irisin (a glycosylated protein) is cleaved from fibronectin type III domain-containing protein 5 (FNDC5), which is expressed mainly in animal muscle tissues and has multiple metabolic regulatory activities. However, their roles in controlling myofiber types in skeletal muscle remain unclear. METHODOLOGY: Two different commercial hybridized pigs, LJH (a crossed pig containing Chinese native pig genotypes) and DLY (Duroc × Landrace × Yorkshire) were selected to analyze FNDC5 mRNA expression and the mRNA composition of four adult myosin heavy chain (MyHC) isoforms (IIIaIIxIIb) in the longissimus dorsi (LD) muscle. C2C12 myoblasts were cultured to investigate the effects of FNDC5 on the four MyHCs mRNA expressive levels, using small interfering RNA for depletion and a eukaryotic expression vector carrying FNDC5 for overexpression. ZLN005 (a small molecule activator of FNDC5's upstream control gene PGC1α) or recombinant human irisin protein were also used. RESULTS: In LD muscle, LJH pigs had the higher FNDC5 mRNA level, and MyHC I or IIa proportion than DLY pigs (P <  0.05). For C2C12 cells in vitro, small interfering RNA (si-592) silencing of FNDC5 expression markedly reduced MyHC IIa mRNA levels (P <  0.05), while FNDC5 overexpression significantly increased MyHC IIa mRNA levels (P <  0.05). Exogenous irisin increased the mRNA levels of PGC1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha), FNDC5, MyHCI, MyHCIIa, NRF1 (nuclear respiratory factor 1), VEGF (vascular endothelial growth factor), and TFAM (mitochondrial transcription factor A,) (P <  0.05), and the enzyme activities of SDH (succinate dehydrogenase), CK (creatine kinase), and MDH (malate dehydrogenase) in C2C12 myotubes (P <  0.05). These results showed that FNDC5 mRNA expression had a significant association with the characteristics of myofiber types in porcine muscle, and participated in regulating MyHCs mRNA expression of C2C12 myogenic differentiation cells in vitro. FNDC5 could be an important factor to control muscle fiber types, which provides a new direction to investigate pork quality via muscle fiber characteristics.

Catch-up growth in intrauterine growth-restricted piglets associated with the restore of pancreatic and intestinal functions via porcine glucagon-like peptide-2 microspheres.

Intrauterine growth restriction (IUGR) results in abnormal morphology and gastrointestinal function, such as reduced villi height and crypt depth, thinner mucosa and muscle layers, and reduced brush border enzyme activities, delayed gastric emptying, increased stress response. As a gastrointestinal growth factor, the manner by which the porcine glucagon-like peptide-2 (pGLP-2) microsphere administration restored the gastrointestinal function and growth performance of IUGR piglets was investigated. Fourteen newborn Duroc × (Yorkshire × Landrace) IUGR piglets (0.92 ± 0.113 kg) were assigned into the IUGR (negative control group) and pGLP-2 microsphere groups. The piglets in group pGLP-2 were intraperitoneally administered with 100 mg pGLP-2 microspheres on day 1 after birth. From days 15 to 26 of trial, the body weight of the pGLP-2 group was significantly higher than that of the control. IUGR piglets of group pGLP-2 showed a significantly increased pancreas weight, serum insulin content and activity of lipase and amylase. Injection of pGLP-2 microspheres restored the intestinal absorptive capacity by significantly increasing the mRNA expression of the sodium-glucose cotransporter 1 in the jejunum and the peptide transporter 1 in the jejunum. It also restored the redox balance by increasing the catalase mRNA expression and decreasing the heat shock protein 70 mRNA expression. In addition, this improvement was associated with the significant increase in gut diameter, length and weight. Therefore, it was concluded that the injection of pGLP-2 microspheres was a suitable therapeutic strategy for compensatory growth in low birth weight IUGR piglets.

A computational network analysis based on targets of antipsychotic agents.

Currently, numerous antipsychotic agents have been developed in the area of pharmacological treatment of schizophrenia. However, the molecular mechanism underlying multi targets of antipsychotics were yet to be explored. In this study we performed a computational network analysis based on targets of antipsychotic agents. We retrieved a total of 96 targets from 56 antipsychotic agents. By expression enrichment analysis, we identified that the expressions of antipsychotic target genes were significantly enriched in liver, brain, blood and corpus striatum. By protein-protein interaction (PPI) network analysis, a PPI network with 77 significantly interconnected target genes was generated. By historeceptomics analysis, significant brain region specific target-drug interactions were identified in targets of dopamine receptors (DRD1-Olanzapine in caudate nucleus and pons (P-value<0.005), DRD2-Bifeprunox in caudate nucleus and pituitary (P-value<0.0005), DRD4-Loxapine in Pineal (P-value<0.00001)) and 5-hydroxytryptamine receptor (HTR2A-Risperidone in occipital lobe, prefrontal cortex and subthalamic nucleus (P-value<0.0001)). By pathway grouped network analysis, 34 significant pathways were identified and significantly grouped into 6 sub networks related with drug metabolism, Calcium signaling, GABA receptors, dopamine receptors, Bile secretion and Gap junction. Our results may provide biological explanation for antipsychotic targets and insights for molecular mechanism of antipsychotic agents.

Therapeutic effects of different doses of polyethylene glycosylated porcine glucagon-like peptide-2 on ulcerative colitis in male rats.

BACKGROUND: Polyethylene glycosylated (PEGylated) porcine glucagon-like peptide-2 (pGLP-2) considerably increases half-life and stability compared with the native pGLP-2, but the effective dose for intestinal damage is still unclear. This study aims to evaluate the available dose of polyethylene glycosylated porcine glucagon-like peptide-2 (PEG-pGLP-2), a modified, long-acting form of pGLP-2 in an experimental rat model of ulcerative colitis. METHODS: Thirty-five male rats were randomly assigned into five groups: control, dextran sodium sulphate (DSS), DSS + PEG-pGLP-2(L), DSS + PEG-pGLP-2(M) and DSS + PEG-pGLP-2(H). Rats in control group received only water; other rats were fed with 5% (w/v) DSS and intraperitoneally administered with 12.5, 25 and 100 nmol/kg PEG-pGLP-2 daily for 6 days. RESULTS: Compared with the control treatment, DSS treatment significantly (p < 0.05) decreased body weight change, colonic length, duodenal villus height and expression of zonula occludens-1, whereas significantly (p < 0.05) increased colonic damage score and expression of claudin-1, interleukin (IL)-1, IL-7, IL-10, interferon-γ and tumour necrosis factor (TNF)-α in colon. However, the three doses of PEG-pGLP-2 all reduced these effects; these treatments significantly (p < 0.05) increased body weight change and duodenal villus height, whereas significantly (p < 0.05) decreased colonic damage score and expression of IL-1, IL-7 and TNF-α in colon. Specifically, low-dose (12.5 nmol/kg/d) PEG-pGLP-2 was effective. CONCLUSIONS: These results indicated that PEG-pGLP-2 is a novel and potentially effective therapy for intestinal healing in a relatively low dose.

Effects of PEGylated porcine glucagon-like peptide-2 therapy in weaning piglets challenged with lipopolysaccharide.

This study aims to evaluate the therapeutic effect of polyethylene glycosylated porcine glucagon-like peptide-2 (pGLP-2), a long-acting form of pGLP-2, in lipopolysaccharide (LPS)-challenged piglets. Eighteen 21-day-old weaning piglets were randomly assigned into three groups: control (saline solution), LPS (100 µg/kg LPS), and PEG-pGLP-2 (10 nmol/kg PEG-pGLP-2+100 µg/kg LPS). All treatments were administered intraperitoneally. Compared with the control treatment, LPS treatment significantly decreased (P<0.05) the villus heights of the duodenum and jejunum, as well as the villus height/crypt depth ratio of the jejunum. However, PEG-pGLP-2 therapy reduced these effects (P>0.05). Specifically, PEG-pGLP-2 infusion significantly increased the villus height/crypt depth ratio of the duodenum (P<0.05) compared with LPS treatment. Compared with the control treatment, LPS treatment significantly increased (P<0.05) the mRNA expression levels of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in the jejunum. However, PEG-pGLP-2 therapy reduced these effects (P<0.05). Specifically, PEG-pGLP-2 infusion significantly decreased (P<0.05) the mRNA expression levels of interleukin (IL)-8 and TNF-α in the duodenum and jejunum, IL-10 in the duodenum, and IFN-γ in the jejunum compared with the LPS treatment. LPS treatment increased the caspase-3 activity of the ileum mucosal (P<0.05), and this effect was significantly reduced by PEG-pGLP-2 treatment. These results indicate that PEG-pGLP-2 infusion alleviates the severity of intestinal injury in weaning piglets by reducing the secretion of inflammatory cytokines and the caspase-3 activity, and increasing the villus height/crypt depth ratio.

Purified PEGylated porcine glucagon-like peptide-2 reduces the severity of colonic injury in a murine model of experimental colitis.

The rapid degradation of porcine glucagon-like peptide-2 (pGLP-2) by the enzyme dipeptidyl peptidase-IV (DPP-IV) is the main impediment in the development of pGLP-2 as a potential therapeutic agent for intestinal dysfunction and damage. In this study, one mono-modified Lys(30)-polyethylene glycol (PEG)-pGLP-2 was prepared using mPEG-succinimidyl propionate. To determine the optimized condition for PEGylation, the reactions were monitored by RP-HPLC and MALDI-TOF-MS. Stability was tested in purified DPP-IV in vitro. In vivo, the protective effects for colonic injury were measured in dextran sulfate sodium (DSS)-induced colitis in mice. The monoPEGylated products reached the maximum yield at 4:1 ratio of mPEG5k-SPA to pGLP-2. An effective method of successfully separating PEGylated pGLP-2 from mPEG-SPA5kD using CM Sepharose Fast Flow resin was established. The half-life of Lys(30)-PEG-pGLP-2 was 16-fold longer than that of pGLP-2 in DPP-IV. The DSS mice exhibited marked weight loss), which was significantly reduced by Lys(30)-PEG-pGLP-2 therapy. DSS treatment significantly increased colonic damage score, which was significantly reduced by administration of Lys(30)-PEG-pGLP-2 in DSS-mice. DSS-induced colitis clearly induced Myeloperoxidase activity in the colon, which was significantly reduced by treatments with 3% DSS-pGLP-2 or 3% DSS-PEG-pGLP-2. These results showed that site-specific Lys(30)-PEG-GLP-2 was resistant to degradation and reduced the severity of colonic injury in murine colitis. The enhanced biological potency of this product highlighted its potential as a therapeutic agent for intestinal diseases.