Ketone bodies promote epididymal white adipose expansion to alleviate liver steatosis in response to a ketogenic diet.

Liver can sense the nutrient status and send signals to other organs to regulate overall metabolic homoeostasis. Herein, we demonstrate that ketone bodies act as signals released from the liver that specifically determine the distribution of excess lipid in epididymal white adipose tissue (eWAT) when exposed to a ketogenic diet (KD). An acute KD can immediately result in excess lipid deposition in the liver. Subsequently, the liver sends the ketone body ß-hydroxybutyrate (BHB) to regulate white adipose expansion, including adipogenesis and lipogenesis, to alleviate hepatic lipid accumulation. When ketone bodies are depleted by deleting 3-hydroxy-3-methylglutaryl-CoA synthase 2 gene in the liver, the enhanced lipid deposition in eWAT but not in inguinal white adipose tissue is preferentially blocked, while lipid accumulation in liver is not alleviated. Mechanistically, ketone body BHB can significantly decrease lysine acetylation of peroxisome proliferator-activated receptor gamma in eWAT, causing enhanced activity of peroxisome proliferator-activated receptor gamma, the key adipogenic transcription factor. These observations suggest that the liver senses metabolic stress first and sends a corresponding signal, that is, ketone body BHB, to specifically promote eWAT expansion to adapt to metabolic challenges.

PGC-1α regulates the interplay between oxidative stress, senescence and autophagy in the ageing retina important in age-related macular degeneration.

We previously showed that mice with knockout in the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A) gene encoding the PGC-1α protein, and nuclear factor erythroid 2 like 2 (NFE2L2) gene, exhibited some features of the age-related macular degeneration (AMD) phenotype. To further explore the mechanism behind the involvement of PGC-1α in AMD pathogenesis we used young (3-month) and old (12-month) mice with knockout in the PPARGC1A gene and age-matched wild-type (WT) animals. An immunohistochemical analysis showed age-dependent different expression of markers of oxidative stress defence, senescence and autophagy in the retinal pigment epithelium of KO animals as compared with their WT counterparts. Multivariate inference testing showed that senescence and autophagy proteins had the greatest impact on the discrimination between KO and WT 3-month animals, but proteins of antioxidant defence also contributed to that discrimination. A bioinformatic analysis showed that PGC-1α might coordinate the interplay between genes encoding proteins involved in antioxidant defence, senescence and autophagy in the ageing retina. These data support importance of PGC-1α in AMD pathogenesis and confirm the utility of mice with PGC-1α knockout as an animal model to study AMD pathogenesis.

Metabolic characteristics of granulosa cell tumor: role of PPARγ signaling†.

Granulosa cell tumors are relatively rare, posing challenges for comprehension and therapeutic development due to limited cases and preclinical models. Metabolic reprogramming, a hallmark of cancer, manifests in granulosa cell tumors with notable lipid accumulation and increased expression of peroxisome proliferator-activated receptor gamma (PPARγ), a key lipid metabolism regulator. The roles of these features, however, remain unclear. In our previous work, we established a granulosa cell tumor model in mice by introducing a constitutively active Pik3ca mutant in oocytes, enabling the study of predictable tumor patterns from postnatal day 50. In this study, we characterized metabolic alterations during tumorigenesis (postnatal day 8 to day 50) and tumor growth (day 50 to day 65) in this model and explored the impact of PPARγ antagonism on human granulosa cell tumor proliferation. The tumor exhibited significant lipid accumulation, with PPARγ and the proliferation marker Ki67 co-localizing at postnatal day 65. Transcriptome analysis demonstrates that pathways for lipid metabolism and mitochondrial oxidation are promoted during tumorigenesis and tumor growth, respectively. Overlappingly upregulated genes during tumorigenesis and tumor growth are associated with lipid metabolism pathways. Correspondingly, mouse granulosa cell tumor shows overexpression of peroxisome proliferator-activated receptor gamma and DGAT2 proteins at postnatal day 65. Furthermore, GW9662 reduces the proliferation of KGN human granulosa cell tumor cells and decreases the phosphorylation of AKT and SMAD3. Our findings identify metabolic abnormalities in ooPIK3CA* granulosa cell tumor model and suggest peroxisome proliferator-activated receptor gamma as a potential driver for primary granulosa cell tumor growth.

VEGFR2 blockade inhibits glioblastoma cell proliferation by enhancing mitochondrial biogenesis.

BACKGROUND: Glioblastoma is an aggressive brain tumor linked to significant angiogenesis and poor prognosis. Anti-angiogenic therapies with vascular endothelial growth factor receptor 2 (VEGFR2) inhibition have been investigated as an alternative glioblastoma treatment. However, little is known about the effect of VEGFR2 blockade on glioblastoma cells per se. METHODS: VEGFR2 expression data in glioma patients were retrieved from the public database TCGA. VEGFR2 intervention was implemented by using its selective inhibitor Ki8751 or shRNA. Mitochondrial biogenesis of glioblastoma cells was assessed by immunofluorescence imaging, mass spectrometry, and western blot analysis. RESULTS: VEGFR2 expression was higher in glioma patients with higher malignancy (grade III and IV). VEGFR2 inhibition hampered glioblastoma cell proliferation and induced cell apoptosis. Mass spectrometry and immunofluorescence imaging showed that the anti-glioblastoma effects of VEGFR2 blockade involved mitochondrial biogenesis, as evidenced by the increases of mitochondrial protein expression, mitochondria mass, mitochondrial oxidative phosphorylation (OXPHOS), and reactive oxygen species (ROS) production, all of which play important roles in tumor cell apoptosis, growth inhibition, cell cycle arrest and cell senescence. Furthermore, VEGFR2 inhibition exaggerated mitochondrial biogenesis by decreased phosphorylation of AKT and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), which mobilized PGC1α into the nucleus, increased mitochondrial transcription factor A (TFAM) expression, and subsequently enhanced mitochondrial biogenesis. CONCLUSIONS: VEGFR2 blockade inhibits glioblastoma progression via AKT-PGC1α-TFAM-mitochondria biogenesis signaling cascade, suggesting that VEGFR2 intervention might bring additive therapeutic values to anti-glioblastoma therapy.

Therapeutic effects of genistein in experimentally induced ulcerative colitis in rats via affecting mitochondrial biogenesis.

Ulcerative colitis (UC) is an inflammatory bowel disease that affects the mucosa of the colon, resulting in severe inflammation and ulcers. Genistein is a polyphenolic isoflavone present in several vegetables, such as soybeans and fava beans. Therefore, we conducted the following study to determine the therapeutic effects of genistein on UC in rats by influencing antioxidant activity and mitochondrial biogenesis and the subsequent effects on the apoptotic pathway. UC was induced in rats by single intracolonic administration of 2 ml of 4% acetic acid. Then, UC rats were treated with 25-mg/kg genistein. Colon samples were obtained to assess the gene and protein expression of nuclear factor erythroid 2-related factor-2 (Nrf2), heme oxygenase-1 (HO-1), peroxisome proliferator-activated receptor-gamma coactivator (PGC-1), mitochondrial transcription factor A (TFAM), B-cell lymphoma 2 (BCL2), BCL2-associated X (BAX), caspase-3, caspase-8, and caspase-9. In addition, colon sections were stained with hematoxylin/eosin to investigate the cell structure. The microimages of UC rats revealed inflammatory cell infiltration, hemorrhage, and the destruction of intestinal glands, and these effects were improved by treatment with genistein. Finally, treatment with genistein significantly increased the expression of PGC-1, TFAM, Nrf2, HO-1, and BCL2 and reduced the expression of BAX, caspase-3, caspase-8, and caspase-9. In conclusion, genistein exerted therapeutic effects against UC in rats. This therapeutic activity involved enhancing antioxidant activity and increasing mitochondrial biogenesis, which reduced cell apoptosis.

Hepatic-specific Pgc-1α ablation drives fibrosis in a MASH model.

BACKGROUND & AIMS: Metabolic dysfunction-associated steatohepatitis (MASH) is a growing cause of chronic liver disease, characterized by fat accumulation, inflammation and fibrosis, which development depends on mitochondrial dysfunction and oxidative stress. Highly expressed in the liver during fasting, peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) regulates mitochondrial and oxidative metabolism. Given the relevant role of mitochondrial function in MASH, we investigated the relationship between PGC-1α and steatohepatitis. METHODS: We measured the hepatic expression of Pgc-1α in both MASH patients and wild-type mice fed a western diet (WD) inducing steatosis and fibrosis. We then generated a pure C57BL6/J strain loss of function mouse model in which Pgc-1α is selectively deleted in the liver and we fed these mice with a WD supplemented with sugar water that accurately mimics human MASH. RESULTS: We observed that the hepatic expression of Pgc-1α is strongly reduced in MASH, in both humans and mice. Moreover, the hepatic ablation of Pgc-1α promotes a considerable reduction of the hepatic mitochondrial respiratory capacity, setting up a bioenergetic harmful environment for liver diseases. Indeed, the lack of Pgc-1α decreases mitochondrial function and increases inflammation, fibrosis and oxidative stress in the scenario of MASH. Intriguingly, this profibrotic phenotype is not linked with obesity, insulin resistance and lipid disbalance. CONCLUSIONS: In a MASH model the hepatic ablation of Pgc-1α drives fibrosis independently from lipid and glucose metabolism. These results add a novel mechanistic piece to the puzzle of the specific and crucial role of mitochondrial function in MASH development.

Prenatal triphenyl phosphate exposure impairs placentation and induces preeclampsia-like symptoms in mice.

Triphenyl phosphate (TPhP) is an organophosphate flame retardant that is widely used in many commercial products. The United States Environmental Protection Agency has listed TPhP as a priority compound that requires health risk assessment. We previously found that TPhP could accumulate in the placentae of mice and impair birth outcomes by activating peroxisome proliferator-activated receptor gamma (PPARγ) in the placental trophoblast. However, the underlying mechanism remains unknown. In this study, we used a mouse intrauterine exposure model and found that TPhP induced preeclampsia (PE)-like symptoms, including new on-set gestational hypertension and proteinuria. Immunofluorescence analysis showed that during placentation, PPARγ was mainly expressed in the labyrinth layer and decidua of the placenta. TPhP significantly decreased placental implantation depth and impeded uterine spiral artery remodeling by activating PPARγ. The results of the in vitro experiments confirmed that TPhP inhibited extravillous trophoblast (EVT) cell migration and invasion by activating PPARγ and inhibiting the PI3K-AKT signaling pathway. Overall, our data demonstrated that TPhP could activate PPARγ in EVT cells, inhibit cell migration and invasion, impede placental implantation and uterine spiral artery remodeling, then induce PE-like symptom and impair birth outcomes. Although the exposure doses used in this study was several orders of magnitude higher than human daily intake, our study highlights the placenta as a potential target organ of TPhP worthy of further research.

Transcriptional coactivator PGC-1α contributes to decidualization by forming a histone-modifying complex with C/EBPß and p300.

We previously reported that CCAAT/enhancer-binding protein beta (C/EBPß) is the pioneer factor inducing transcription enhancer mark H3K27 acetylation (H3K27ac) in the promoter and enhancer regions of genes encoding insulin-like growth factor-binding protein-1 (IGFBP-1) and prolactin (PRL) and that this contributes to decidualization of human endometrial stromal cells (ESCs). Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α; PPARGC1A) is a transcriptional coactivator known to regulate H3K27ac. However, although PGC-1α is expressed in ESCs, the potential role of PGC-1α in mediating decidualization is unclear. Here, we investigated the involvement of PGC-1α in the regulation of decidualization. We incubated ESCs with cAMP to induce decidualization and knocked down PPARGC1A to inhibit cAMP-induced expression of IGFBP-1 and PRL. We found cAMP increased the recruitment of PGC-1α and p300 to C/EBPß-binding sites in the promoter and enhancer regions of IGFBP-1 and PRL, corresponding with increases in H3K27ac. Moreover, PGC-1α knockdown inhibited these increases, suggesting PGC-1α forms a histone-modifying complex with C/EBPß and p300 at these regions. To further investigate the regulation of PGC-1α, we focused on C/EBPß upstream of PGC-1α. We found cAMP increased C/EBPß recruitment to the novel enhancer regions of PPARGC1A. Deletion of these enhancers decreased PGC-1α expression, indicating that C/EBPß upregulates PGC-1α expression by binding to novel enhancer regions. In conclusion, PGC-1α is upregulated by C/EBPß recruitment to novel enhancers and contributes to decidualization by forming a histone-modifying complex with C/EBPß and p300, thereby inducing epigenomic changes in the promoters and enhancers of IGFBP-1 and PRL.

A high fat, high sugar diet induces hepatic Peroxisome proliferator-activated receptor gamma coactivator 1-alpha promoter hypermethylation in male Wistar rats.

Previously we reported that a high fat, high sugar (HFHS) diet induced adiposity, hyperinsulinaemia, hyperleptinaemia, hypertriglyceridaemia and increased liver mass in male Wistar rats. In the present study, the mechanisms underlying the increased liver mass were further elucidated by assessing hepatic lipid accumulation and the expression and methylation status of key metabolic genes using histology, quantitative real-time PCR and pyrosequencing, respectively. The HFHS diet induced hepatic steatosis, increased hepatic triglycerides (1.8-fold, p < 0.001), and increased the expression of sterol regulatory element-binding transcription factor 1 (Srebf1) (2.0-fold, p < 0.001) and peroxisome proliferator-activated receptor gamma (Pparg) (1.7-fold, p = 0.017) in the liver. The expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (Pgc1a) was decreased (2.6-fold, p < 0.010), which was accompanied by hypermethylation (p = 0.018) of a conserved CpG site in the promoter of Pgc1a in HFHS fed rats compared to controls. In silico analysis identified putative binding sites for CCAAT/enhancer-binding protein beta (C/EBPß) and hepatocyte nuclear factor 1 (HNF1) within proximity to the hypermethylated CpG. As Pgc1a is a co-activator of several transcription factors regulating multiple metabolic pathways, hypermethylation of this conserved CpG site in the promoter of Pgc1a may be one possible mechanism contributing to the development of hepatic steatosis in response to a HFHS diet. However, further work is required to confirm the role of Pgc1a in steatosis.

Genome-wide analysis of histone modifications that underlie the dynamic changes in gene expression during decidualization in human endometrial stromal cells.

Human endometrial stromal cells (hESCs) undergo a differentiation process with dramatic changes in cell functions during the menstrual cycle, which is called decidualization. This is an important event for implantation of the embryo and successful pregnancy. Defective decidualization can cause implantation failure, miscarriage, and unexplained infertility. A number of genes are upregulated or downregulated during decidualization. Recent studies have shown that epigenetic mechanisms are involved in the regulation of decidualization-related genes and that histone modifications occur throughout the genome during decidualization. The present review focuses on the involvement of genome-wide histone modifications in dramatic changes in gene expression during decidualization. The main histone modifications are the increases of H3K27ac and H3K4me3, which activate transcription. C/EBPß works as a pioneer factor throughout the genome by recruiting p300. This is the main cause of the genome-wide acetylation of H3K27 during decidualization. Histone modifications were observed in both the proximal promoter and distal enhancer regions. Genome editing experiments show that the distal regions have transcriptional activities, which suggests that decidualization induces the interactions between proximal promoter and distal enhancer regions. Taken together, these findings show that gene regulation during decidualization is closely associated with genome-wide changes of histone modifications. This review provides new insights regarding the cases of implantation failure in terms of decidualization insufficiency owing to epigenetic dysregulation, and may lead to novel treatment options for women with implantation failure.

Global and Regional DNA methylation silencing of PPARγ Associated with Glioblastoma Multiforme Pathogenesis.

BACKGROUND: The relationship between peroxisome proliferator-activated receptor gamma (PPARγ) expression level and epigenetic modifications occurring in glioblastoma multiforme (GBM) pathogenesis is largely unknown. Herein, we examine the association of PPARγ expression with its promoter and genomic global DNA methylation status, as well as DNA methyltransferases (DNMTs) gene expression in GBM patients. METHODS: We examined the patterns of promoter methylation and PPARγ expression in 26 GBM tissues and 13 adjacent non-tumor tissues by methylation-specific PCR (MSP), real-time PCR, and ELISA, respectively. Also, we examined the genomic global 5-methyl cytosine levels and DNMTs gene expression using ELISA and real-time PCR methods, respectively. RESULTS: We found that hypermethylation on a specific region of the PPARγ promoter is significantly associated with the downregulation of the PPARγ gene and protein level in GBM patients. Interestingly, the amount of 5-methyl cytosine level was significantly reduced in GBM patients and positively correlated with PPARγ protein expression. Furthermore, the expression level of DNMT1, DNMT3A, and 3B were upregulated in GBM patients and the average expression level of all three DNMTs was positively correlated with tumor area. Also, we found that tumors from cortical regions exhibited a higher global DNA hypomethylation and PPARγ hypermethylation was related to the increase in GBM risk. CONCLUSION: Our study demonstrated that global DNA methylation and PPARγ epigenetic silencing is associated with the GBM risk. Our data provide a novel molecular mechanistic insight into epigenetic silencing of PPARγ in GBM patients that may be relevant as a key tumor marker for GBM pathogenesis.

Protein kinase C beta relieves autism-like behavior in EN2 knockout mice via upregulation of the FTO/PGC-1α/UCP1 axis.

Increasing evidence suggests that disruption of neuron activity contributes to the autistic phenotype. Thus, we aimed in this study to explore the role of protein kinase C beta (PKCß) in the regulation of neuron activity in an autism model. The expression of PKCß in the microarray data of autism animal models was obtained from the Gene Expression Omnibus database. Then, mice with autism-like behavior were prepared in EN2 knockout (-/- ) mice. The interaction between PKCß on fat mass and obesity-associated protein (FTO) as well as between PGC-1α and uncoupling protein 1 (UCP1) were characterized. The effect of FTO on the N6 -methyladenosine (m6A) modification level of proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) was assayed. Following transfection of overexpressed PKCß and/or silenced UCP1, effects of PKCß and UCP1 in autism-like behaviors in EN2-/- mice were analyzed. Results showed that PKCß was downregulated in EN2-/- mouse brain tissues or neurons. PKCß promoted the expression and stability of FTO, which downregulated the m6A modification level of PGC-1α to promote its expression. Moreover, PGC-1α positively targeted the expression of UCP1. PKCß knockdown enhanced sociability and spatial exploration ability, and reduced neuron apoptosis in EN2-/- mouse models of autism, which was reversed by UCP1 overexpression. Collectively, PKCß overexpression leads to activation of the FTO/m6A/PGC-1α/UCP1 axis, thus inhibiting neuron apoptosis and providing neuroprotection in mice with autism-like behavior.

Prenatal airborne polycyclic aromatic hydrocarbon exposure, altered regulation of peroxisome proliferator-activated receptor gamma (Ppar)γ, and links with mammary cancer.

Environmental exposure to polycyclic aromatic hydrocarbons (PAH) has been shown to be associated with chronic disease outcomes through multiple mechanisms including altered regulation of the transcription factor peroxisome proliferator-activated receptor gamma (Ppar) γ. Because PAH exposure and Pparγ each have been associated with mammary cancer, we asked whether PAH would induce altered regulation of Pparγ in mammary tissue, and whether this association may underlie the association between PAH and mammary cancer. Pregnant mice were exposed to aerosolized PAH at proportions that mimic equivalent human exposures in New York City air. We hypothesized that prenatal PAH exposure would alter Pparγ DNA methylation and gene expression and induce the epithelial to mesenchymal transition (EMT) in mammary tissue of offspring (F1) and grandoffspring (F2) mice. We also hypothesized that altered regulation of Pparγ in mammary tissue would associate with biomarkers of EMT, and examined associations with whole body weight. We found that prenatal PAH exposure lowered Pparγ mammary tissue methylation among grandoffspring mice at postnatal day (PND) 28. However, PAH exposure did not associate with altered Pparγ gene expression or consistently with biomarkers of EMT. Finally, lower Pparγ methylation, but not gene expression, was associated with higher body weight among offspring and grandoffspring mice at PND28 and PND60. Findings suggest additional evidence of multi-generational adverse epigenetic effects of prenatal PAH exposure among grandoffspring mice.

Activation of PGC-1α-dependent mitochondrial biogenesis supports therapeutic effects of silibinin against type I diabetic periodontitis.

AIM: To investigate whether silibinin impacts diabetic periodontitis (DP) via mitochondrial regulation. MATERIALS AND METHODS: In vivo, rats were divided into control, diabetes, DP and DP combined with silibinin groups. Diabetes and periodontitis were induced by streptozocin and silk ligation, respectively. Bone turnover was evaluated by microcomputed tomography, histology and immunohistochemistry. In vitro, human periodontal ligament cells (hPDLCs) were exposed to hydrogen peroxide (H2 O2 ) with or without silibinin. Osteogenic function was analysed by Alizarin Red and alkaline phosphatase staining. Mitochondrial function and biogenesis were investigated by mitochondrial imaging assays and quantitative polymerase chain reaction. Activator and lentivirus-mediated knockdown of peroxisome proliferator-activated receptor gamma-coactivator 1-alpha (PGC-1α), a critical regulator of mitochondria biogenesis, was used to explore the mitochondrial mechanisms. RESULTS: Silibinin attenuated periodontal destruction and mitochondrial dysfunction and enhanced mitochondrial biogenesis and PGC-1α expression in rats with DP. Meanwhile, silibinin promoted cell proliferation, osteogenesis and mitochondrial biogenesis and increased the PGC-1α level in hPDLCs exposed to H2 O2 . Silibinin also protected PGC-1α from proteolysis in hPDLCs. Furthermore, both silibinin and activator of PGC-1α ameliorated cellular injury and mitochondrial abnormalities in hPDLCs, while knockdown of PGC-1α abolished the beneficial effect of silibinin. CONCLUSIONS: Silibinin attenuated DP through the promotion of PGC-1α-dependent mitochondrial biogenesis.

PGC 1α-Mediates Mitochondrial Damage in the Liver by Inhibiting the Mitochondrial Respiratory Chain as a Non-cholinergic Mechanism of Repeated Low-Level Soman Exposure.

This work aimed to assess whether mitochondrial damage in the liver induced by subacute soman exposure is caused by peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) and whether PGC-1α regulates mitochondrial respiratory chain damage. Toxicity mechanism research may provide theoretical support for developing anti-toxic drugs in the future. First, a soman animal model was established in male Sprague-Dawley (SD) rats by subcutaneous soman injection. Then, liver damage was biochemically evaluated, and acetylcholinesterase (AChE) activity was also determined. Transmission electron microscopy (TEM) was performed to examine liver mitochondrial damage, and high-resolution respirometry was carried out for assessing mitochondrial respiration function. In addition, complex I-IV levels were quantitatively evaluated in isolated liver mitochondria by enzyme-linked immunosorbent assay (ELISA). PGC-1α levels were detected with a Jess capillary-based immunoassay device. Finally, oxidative stress was analyzed by quantifying superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG), and reactive oxygen species (ROS) levels. Repeated low-level soman exposure did not alter AChE activity, while increasing morphological damage of liver mitochondria and liver enzyme levels in rat homogenates. Complex I, II and I + II activities were 2.33, 4.95, and 5.22 times lower after treatment compared with the control group, respectively. Among complexes I-IV, I-III decreased significantly (p < 0.05), and PGC-1α levels were 1.82 times lower after soman exposure than in the control group. Subacute soman exposure significantly increased mitochondrial ROS production, which may cause oxidate stress. These findings indicated dysregulated mitochondrial energy metabolism involves PGC-1α protein expression imbalance, revealing non-cholinergic mechanisms for soman toxicity.

Increasing brain glucose uptake by Gypenoside LXXV ameliorates cognitive deficits in a mouse model of diabetic Alzheimer's disease.

We have previously reported that Gypenoside LXXV (GP-75), a novel natural PPARγ agonist isolated from Gynostemma pentaphyllum, ameliorated cognitive deficits in db/db mice. In this study, we further investigated the beneficial effects on cognitive impairment in APP/PS1 mice and a mouse model of diabetic AD (APP/PS1xdb/db mice). Interestingly, intragastric administration of GP-75 (40 mg/kg/day) for 3 months significantly attenuated cognitive deficits in APP/PS1 and APP/PS1xdb/db mice. GP-75 treatment markedly reduced the levels of glucose, HbA1c and insulin in serum and improved glucose tolerance and insulin sensitivity in APP/PS1xdb/db mice. Notably, GP-75 treatment decreased the ß-amyloid (Aß) burden, as measured by 11 C-PIB PET imaging. Importantly, GP-75 treatment increased brain glucose uptake as measured by 18 F-FDG PET imaging. Moreover, GP-75 treatment upregulated PPARγ and increased phosphorylation of Akt (Ser473) and GLUT4 expression levels but decreased phosphorylation of IRS-1 (Ser616) in the hippocampi of both APP/PS1 and APP/PS1xdb/db mice. Furthermore, GP-75-induced increases in GLUT4 membrane translocation in primary hippocampal neurons from APP/PS1xdb/db mice was abolished by cotreatment with the selective PPARγ antagonist GW9662 or the PI3K inhibitor LY294002. In summary, GP-75 ameliorated cognitive deficits in APP/PS1 and APP/PS1xdb/db mice by enhancing glucose uptake via activation of the PPARγ/Akt/GLUT4 signaling pathways.

Structural Biology Inspired Development of a Series of Human Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) Ligands: From Agonist to Antagonist.

Recent progress in the structural and molecular pharmacological understanding of the nuclear receptor, peroxisome proliferator-activated receptor gamma (hPPARγ)-a transcription factor with pleiotropic effects on biological responses-has enabled the investigation of various graded hPPARγ ligands (full agonist, partial agonist, and antagonist). Such ligands are useful tools to investigate the functions of hPPARγ in detail and are also candidate drugs for the treatment of hPPARγ-mediated diseases, such as metabolic syndrome and cancer. This review summarizes our medicinal chemistry research on the design, synthesis, and pharmacological evaluation of a covalent-binding and non-covalent-binding hPPARγ antagonist, both of which have been created based on our working hypothesis of the helix 12 (H12) holding induction/inhibition concept. X-ray crystallographic analyses of our representative antagonists complexed with an hPPARγ ligand binding domain (LBD) indicated the unique binding modes of hPPARγ LBD, which are quite different from the binding modes observed for hPPARγ agonists and partial agonists.

Pre-Diabetes-Linked miRNA miR-193b-3p Targets PPARGC1A, Disrupts Metabolic Gene Expression Profile and Increases Lipid Accumulation in Hepatocytes: Relevance for MAFLD.

Distinct plasma microRNA profiles associate with different disease features and could be used to personalize diagnostics. Elevated plasma microRNA hsa-miR-193b-3p has been reported in patients with pre-diabetes where early asymptomatic liver dysmetabolism plays a crucial role. In this study, we propose the hypothesis that elevated plasma hsa-miR-193b-3p conditions hepatocyte metabolic functions contributing to fatty liver disease. We show that hsa-miR-193b-3p specifically targets the mRNA of its predicted target PPARGC1A/PGC1α and consistently reduces its expression in both normal and hyperglycemic conditions. PPARGC1A/PGC1α is a central co-activator of transcriptional cascades that regulate several interconnected pathways, including mitochondrial function together with glucose and lipid metabolism. Profiling gene expression of a metabolic panel in response to overexpression of microRNA hsa-miR-193b-3p revealed significant changes in the cellular metabolic gene expression profile, including lower expression of MTTP, MLXIPL/ChREBP, CD36, YWHAZ and GPT, and higher expression of LDLR, ACOX1, TRIB1 and PC. Overexpression of hsa-miR-193b-3p under hyperglycemia also resulted in excess accumulation of intracellular lipid droplets in HepG2 cells. This study supports further research into potential use of microRNA hsa-miR-193b-3p as a possible clinically relevant plasma biomarker for metabolic-associated fatty liver disease (MAFLD) in dysglycemic context.

Expression of Cannabinoid Receptors in the Trigeminal Ganglion of the Horse.

Cannabinoid receptors are expressed in human and animal trigeminal sensory neurons; however, the expression in the equine trigeminal ganglion is unknown. Ten trigeminal ganglia from five horses were collected post-mortem from an abattoir. The expression of cannabinoid receptors type 1 (CB1R) and type 2 (CB2R), and the cannabinoid-related receptors like transient receptor potential vanilloid type 1 (TRPV1), peroxisome proliferator-activated receptor gamma (PPARÉ£), and G protein-related receptor 55 (GPR55) in the trigeminal ganglia (TG) of the horse were studied, using immunofluorescence on cryosections and formalin-fixed paraffin-embedded (FFPE) sections. Neurons and glial cells were identified using fluorescent Nissl staining NeuroTrace® and an antibody directed against the glial marker glial fibrillary acidic protein (GFAP), respectively. Macrophages were identified by means of an antibody directed against the macrophages/microglia marker ionized calcium-binding adapter molecule 1 (IBA1). The protein expression of CB1R, CB2R, TRPV1, and PPARÉ£ was found in the majority of TG neurons in both cryosections and FFPE sections. The expression of GPR55 immunoreactivity was mainly detectable in FFPE sections, with expression in the majority of sensory neurons. Some receptors were also observed in glial cells (CB2R, TRPV1, PPARγ, and GPR55) and inflammatory cells (PPARγ and GPR55). These results support further investigation of such receptors in disorders of equine trigeminal neuronal excitability.

Verbascoside Elicits Its Beneficial Effects by Enhancing Mitochondrial Spare Respiratory Capacity and the Nrf2/HO-1 Mediated Antioxidant System in a Murine Skeletal Muscle Cell Line.

Muscle weakness and muscle loss characterize many physio-pathological conditions, including sarcopenia and many forms of muscular dystrophy, which are often also associated with mitochondrial dysfunction. Verbascoside, a phenylethanoid glycoside of plant origin, also named acteoside, has shown strong antioxidant and anti-fatigue activity in different animal models, but the molecular mechanisms underlying these effects are not completely understood. This study aimed to investigate the influence of verbascoside on mitochondrial function and its protective role against H2O2-induced oxidative damage in murine C2C12 myoblasts and myotubes pre-treated with verbascoside for 24 h and exposed to H2O2. We examined the effects of verbascoside on cell viability, intracellular reactive oxygen species (ROS) production and mitochondrial function through high-resolution respirometry. Moreover, we verified whether verbascoside was able to stimulate nuclear factor erythroid 2-related factor (Nrf2) activity through Western blotting and confocal fluorescence microscopy, and to modulate the transcription of its target genes, such as heme oxygenase-1 (HO-1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), by Real Time PCR. We found that verbascoside (1) improved mitochondrial function by increasing mitochondrial spare respiratory capacity; (2) mitigated the decrease in cell viability induced by H2O2 and reduced ROS levels; (3) promoted the phosphorylation of Nrf2 and its nuclear translocation; (4) increased the transcription levels of HO-1 and, in myoblasts but not in myotubes, those of PGC-1α. These findings contribute to explaining verbascoside's ability to relieve muscular fatigue and could have positive repercussions for the development of therapies aimed at counteracting muscle weakness and mitochondrial dysfunction.