Role of Peroxisome Proliferator-Activated Receptor (PPAR)δ in Embryonic Stem Cell Proliferation

Protein Dynamic Landscape of Pig Embryos during Peri-Implantation Development

Properly developed embryos are critical for successful embryo implantation. The dynamic landscape of proteins as executors of biological processes in pig peri-implantation embryos has not been reported so far. In this study, we collected pig embryos from days 9, 12, and 15 of pregnancy during the peri-implantation stage for a PASEF-based quantitative proteomic analysis. In total, approximately 8000 proteins were identified. These proteins were classified as stage-exclusive proteins and stage-specific proteins, respectively, based on their presence and dynamic abundance changes at each stage. Functional analysis showed that their roles are consistent with the physiological processes of corresponding stages, such as the biosynthesis of amino acids and peptides at P09, the regulation of actin cytoskeletal organization and complement activation at P12, and the vesicular transport at P15. Correlation analysis between mRNAs and proteins showed a general positive correlation between pig peri-implantation embryonic mRNAs and proteins. Cross-species comparisons with human early embryos identified some conserved proteins that may be important in regulating embryonic development, such as STAT3, AP2A1, and PFAS. Our study provides a comprehensive overview of the pig embryo proteome during implantation, fills gaps in relevant developmental studies, and identifies some important proteins that may serve as potential targets for future research.

Effect of Galactooligosaccharide on PPARs/PI3K/Akt Pathway and Gut Microbiota in High-Fat and High-Sugar Diet Combined with STZ-Induced GDM Rat Model

Gestational diabetes mellitus (GDM) is a metabolic disorder, characterized by underlying glucose intolerance, diabetes onset or first diagnosis during pregnancy. Galactooligosaccharide (GOS) is essential for consumer protection as food supplementation. However, there is limited understanding of the effects of GOS on GDM. We successfully established a GDM rat model to explore GOS whether participated in PPARs/PI3K/Akt pathway and gut microbiota metabolites to treat for GDM. In this study, compared with the GDM group, GOS administration lowered the levels of TG, LDL-C, and HDL-C in rat serum, as well as improved the pathological changes pancreatic, liver, and kidney tissues. Compared with the GDM group, the protein expressions of PPARα, PPARγ, and PPARβ/δ markedly enhanced in GOS-treated groups (P < 0.01). Moreover, GOS administration upregulated the protein expressions of PPARα, PPARβ, PPARγ, PI3K, Akt, GLUT4, Bax, and Bcl2. GOS administration altered gut microbiota metabolites, including both SCFAs and BAs. Correlation analysis revealed close relationships between gut microbiota and experimental indicators. This study indicated that GOS effectively improved GDM in rats through the modulation of PPARs/PI3K/Akt pathway and gut microbiota. Thus, the GOS could be recommended as a candidate for novel therapy of GDM.

Therapeutic Efficacies of Berberine against Neurological Disorders: An Update of Pharmacological Effects and Mechanisms

Neurological disorders are ranked as the leading cause of disability and the second leading cause of death worldwide, underscoring an urgent necessity to develop novel pharmacotherapies. Berberine (BBR) is a well-known phytochemical isolated from a number of medicinal herbs. BBR has attracted much interest for its broad range of pharmacological actions in treating and/or managing neurological disorders. The discoveries in basic and clinical studies of the effects of BBR on neurological disorders in the last decade have provided novel evidence to support the potential therapeutical efficacies of BBR in treating neurological diseases. In this review, we summarized the pharmacological properties and therapeutic applications of BBR against neurological disorders in the last decade. We also emphasized the major pathways modulated by BBR, which provides firm evidence for BBR as a promising drug candidate for neurological disorders.

Modulation of PPAR signaling disrupts pancreas development in the zebrafish, Danio rerio

Peroxisome Proliferator Activated Receptors (PPARs) are transcription factors that regulate processes such as lipid and glucose metabolism. Synthetic PPAR ligands, designed as therapeutics for metabolic disease, provide a tool to assess the relationship between PPAR activity and pancreas development in vivo, an area that remains poorly characterized. Here, we aim to assess the effects of PPAR agonists and antagonists on gene expression, embryonic morphology and pancreas development in transgenic zebrafish embryos. To evaluate developmental perturbations, we assessed gross body and pancreas morphology at 4 days post fertilization (dpf) in response to developmental exposures with PPARα, PPARγ, and PPARβ/δ agonists and antagonists at 0, 0.01, 0.1, 1, and 10 μM concentrations. All ligand exposures, with the exception of the PPARα agonist, resulted in significantly altered fish length and yolk sac area. PPARγ agonist and antagonist had higher incidence of darkened yolk sac and craniofacial deformities, whereas PPARα antagonist had higher incidence of pericardial edema and death. Significantly reduced endocrine pancreas area was observed in both PPARγ ligands and PPARα agonist exposed embryos, some of which also exhibited aberrant endocrine pancreas morphology. Both PPARβ/δ ligands caused reduced exocrine pancreas length and novel aberrant phenotype, and disrupted gene expression of pancreatic targets pdx1, gcga, and try. Lipid staining was performed at 8 dpf and revealed altered lipid accumulation consistent with isoform function. These data indicate chronic exposure to synthetic ligands may induce morphological and pancreatic defects in zebrafish embryos.

Peroxisome Proliferator-Activated Receptors (PPAR), fatty acids and microRNAs: Implications in women delivering low birth weight babies

Low birth weight (LBW) babies are associated with neonatal morbidity and mortality and are at increased risk for noncommunicable diseases (NCDs) in later life. However, the molecular determinants of LBW are not well understood. Placental insufficiency/dysfunction is the most frequent etiology for fetal growth restriction resulting in LBW and placental epigenetic processes are suggested to be important regulators of pregnancy outcome. Early life exposures like altered maternal nutrition may have long-lasting effects on the health of the offspring via epigenetic mechanisms like DNA methylation and microRNA (miRNA) regulation. miRNAs have been recognized as major regulators of gene expression and are known to play an important role in placental development. Angiogenesis in the placenta is known to be regulated by transcription factor peroxisome proliferator-activated receptor (PPAR) which is activated by ligands such as long-chain-polyunsaturated fatty acids (LCPUFA). In vitro studies in different cell types indicate that fatty acids can influence epigenetic mechanisms like miRNA regulation. We hypothesize that maternal fatty acid status may influence the miRNA regulation of PPAR genes in the placenta in women delivering LBW babies. This review provides an overview of miRNAs and their regulation of PPAR gene in the placenta of women delivering LBW babies.Abbreviations: AA - Arachidonic Acid; Ago2 - Argonaute2; ALA - Alpha-Linolenic Acid; ANGPTL4 - Angiopoietin-Like Protein 4; C14MC - Chromosome 14 miRNA Cluster; C19MC - Chromosome 19 miRNA Cluster; CLA - Conjugated Linoleic Acid; CSE - Cystathionine γ-Lyase; DHA - Docosahexaenoic Acid; EFA - Essential Fatty Acids; E2F3 - E2F transcription factor 3; EPA - Eicosapentaenoic Acid; FGFR1 - Fibroblast Growth Factor Receptor 1; GDM - Gestational Diabetes Mellitus; hADMSCs - Human Adipose Tissue-Derived Mesenchymal Stem Cells; hBMSCs - Human Bone Marrow Mesenchymal Stem Cells; HBV - Hepatitis B Virus; HCC - Hepatocellular Carcinoma; HCPT - Hydroxycamptothecin; HFD - High-Fat Diet; Hmads - Human Multipotent Adipose-Derived Stem; HSCS - Human Hepatic Stellate Cells; IUGR - Intrauterine Growth Restriction; LA - Linoleic Acid; LBW - Low Birth Weight; LCPUFA - Long-Chain Polyunsaturated Fatty Acids; MEK1 - Mitogen-Activated Protein Kinase 1; MiRNA - MicroRNA; mTOR - Mammalian Target of Rapamycin; NCDs - NonCommunicable Diseases; OA - Oleic Acid; PASMC - Pulmonary Artery Smooth Muscle Cell; PLAG1 - Pleiomorphic Adenoma Gene 1; PPAR - Peroxisome Proliferator-Activated Receptor; PPARα - PPAR alpha; PPARγ - PPAR gamma; PPARδ - PPAR delta; pre-miRNA - precursor miRNA; RISC - RNA-Induced Silencing Complex; ROS - Reactive Oxygen Species; SAT - Subcutaneous Adipose Tissue; WHO - World Health Organization.

Low-Concentration Essential Amino Acids in PZM-3 Improve the Developmental Competence of Porcine Embryos Produced by Handmade Cloning

Essential amino acids (EAA) of inappropriate concentration have been reported to compromise the development of embryo. This study aimed to investigate the effect of EAA on the developmental competence of porcine embryos produced by either handmade cloning (HMC) or parthenogenetic activation (PA). In experiment 1, we examined the in vitro developmental competence of PA embryos after culture in PZM-3 containing different concentrations (v/v) of EAA (0%, 1%, and 2%). The results indicated that reducing the concentration of EAA from 2% to 1% significantly improved the blastocyst formation (36% vs. 54%), while 0% would compromise the blastocyst formation rate (54% vs. 38%). In experiment 2, we further investigated the effect of EAA concentration (1% and 2%) on the in vitro developmental competence and gene expression of HMC embryos. Blastocyst rate significantly increased by reducing concentration of EAA (41% vs. 53%) and those genes upregulated were enriched in oxidative phosphorylation, PPAR signaling pathway, and metabolism-related pathways. In experiment 3, the in vivo developmental competence of HMC embryos cultured in the medium supplemented with 1% EAA was examined. Embryos derived from both non-gene-modified fetal fibroblasts (FFs) and gene-modified fetal fibroblasts (GMFFs) were transferred to recipients. The pregnancy rates were 83% and 78% separately. Out of the pregnancies, 5 (FFs) and 6 (GMFFs) were successfully developed to term. Our study indicates that supplementing EAA to embryo culture medium at a concentration of 1% can improve the in vitro developmental competence of porcine HMC embryos and the blastocyst obtained can successfully develop to term, which could be beneficial for the production of gene-modified piglets.

Long-chain polyunsaturated fatty acids regulation of PPARs, signaling: Relationship to tissue development and aging

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that function as ligand-dependent transcription factors that can be activated by different types of fatty acids (FAs). Three isoforms of PPARs have been identify, namely, PPARα, PPARβ/δ, and PPARγ, which are able to bind long-chain polyunsaturated FAs (LCPUFAs), n-3 LCPUFAs being bound with greater affinity to achieve activation. FA binding induces a conformational change of the nuclear receptors, triggering the transcription of specific genes including those encoding for various metabolic and cellular processes such as FA β-oxidation and adipogenesis, thus representing key mediators of lipid homeostasis. In addition, PPARs have important roles during placental, embryonal, and fetal development, and in the regulation of processes related to aging comprising oxidative stress, inflammation, and neuroprotection. The aim of this review was to assess the role of FAs as PPARs ligands, in terms of their main functions associated with FA metabolism and their relevance in the prevention and treatment of related pathologies during human life span.

Activation of PPARδ: from computer modelling to biological effects

PPARδ is a ligand-activated receptor that dimerizes with another nuclear receptor of the retinoic acid receptor family. The dimers interact with other co-activator proteins and form active complexes that bind to PPAR response elements and promote transcription of genes involved in lipid metabolism. It appears that various natural fatty acids and their metabolites serve as endogenous activators of PPARδ; however, there is no consensus in the literature on the nature of the prime activators of the receptor. In vitro and cell-based assays of PPARδ activation by fatty acids and their derivatives often produce conflicting results. The search for synthetic and selective PPARδ agonists, which may be pharmacologically useful, is intense. Current rational modelling used to obtain such compounds relies mostly on crystal structures of synthetic PPARδ ligands with the recombinant ligand binding domain (LBD) of the receptor. Here, we introduce an original computational prediction model for ligand binding to PPARδ LBD. The model was built based on EC50 data of 16 ligands with available crystal structures and validated by calculating binding probabilities of 82 different natural and synthetic compounds from the literature. These compounds were independently tested in cell-free and cell-based assays for their capacity to bind or activate PPARδ, leading to prediction accuracy of between 70% and 93% (depending on ligand type). This new computational tool could therefore be used in the search for natural and synthetic agonists of the receptor.