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Reproductive Toxicology (Elmsford, N.Y.) Jun 2022Widespread use of phthalates as solvents and plasticizers leads to everyday human exposure. The mechanisms by which phthalate metabolites act as ovarian toxicants are...
Widespread use of phthalates as solvents and plasticizers leads to everyday human exposure. The mechanisms by which phthalate metabolites act as ovarian toxicants are not fully understood. Thus, this study tested the hypothesis that the phthalate metabolites monononyl phthalate (MNP), monoisononyl phthalate (MiNP), mono(2-ethylhexyl) phthalate (MEHP), monobenzyl phthalate (MBzP), monobutyl phthalate (MBP), monoisobutyl phthalate (MiBP), and monoethyl phthalate (MEP) act through peroxisome proliferator-activated receptors (PPARs) in mouse granulosa cells. Primary granulosa cells were isolated from CD-1 mice and cultured with vehicle control (dimethyl sulfoxide) or MNP, MiNP, MEHP, MBzP, MBP, MiBP, or MEP (0.4-400 μM) for 24 h. Following culture, qPCR was performed for known PPAR targets, Fabp4 and Cd36. Treatment with the phthalate metabolites led to significant changes in Fabp4 and Cd36 expression relative to control in dose-dependent or nonmonotonic fashion. Primary granulosa cell cultures were also transfected with a DNA plasmid containing luciferase expressed under the control of a consensus PPAR response element. MNP, MiNP, MEHP, and MBzP caused dose-dependent changes in expression of luciferase, indicating the presence of functional endogenous PPAR receptors in the granulosa cells that respond to phthalate metabolites. The effects of phthalate metabolites on PPAR target genes were inhibited in most of the cultures by co-treatment with the PPAR-γ inhibitor, T0070907, or with the PPAR-α inhibitor, GW6471. Collectively, these data suggest that some phthalate metabolites may act through endogenous PPAR nuclear receptors in the ovary and that the differing structures of the phthalates result in different levels of activity.
Topics: Animals; Environmental Exposure; Environmental Pollutants; Female; Mice; Ovary; PPAR alpha; PPAR gamma; Phthalic Acids; Plasticizers
PubMed: 35421560
DOI: 10.1016/j.reprotox.2022.04.002 -
Nature Communications Sep 2020Peripheral sensory neurons regenerate their axon after nerve injury to enable functional recovery. Intrinsic mechanisms operating in sensory neurons are known to...
Peripheral sensory neurons regenerate their axon after nerve injury to enable functional recovery. Intrinsic mechanisms operating in sensory neurons are known to regulate nerve repair, but whether satellite glial cells (SGC), which completely envelop the neuronal soma, contribute to nerve regeneration remains unexplored. Using a single cell RNAseq approach, we reveal that SGC are distinct from Schwann cells and share similarities with astrocytes. Nerve injury elicits changes in the expression of genes related to fatty acid synthesis and peroxisome proliferator-activated receptor (PPARα) signaling. Conditional deletion of fatty acid synthase (Fasn) in SGC impairs axon regeneration. The PPARα agonist fenofibrate rescues the impaired axon regeneration in mice lacking Fasn in SGC. These results indicate that PPARα activity downstream of FASN in SGC contributes to promote axon regeneration in adult peripheral nerves and highlight that the sensory neuron and its surrounding glial coat form a functional unit that orchestrates nerve repair.
Topics: Animals; Axons; Cell Proliferation; Fatty Acid Synthases; Female; Humans; Male; Mice; Mice, Inbred C57BL; Nerve Regeneration; Neuroglia; PPAR alpha; Peripheral Nerve Injuries; Peripheral Nerves; Sensory Receptor Cells; Signal Transduction
PubMed: 32994417
DOI: 10.1038/s41467-020-18642-y -
Molecular Cancer Apr 2024Sorafenib is a major nonsurgical option for patients with advanced hepatocellular carcinoma (HCC); however, its clinical efficacy is largely undermined by the...
BACKGROUND AND AIMS
Sorafenib is a major nonsurgical option for patients with advanced hepatocellular carcinoma (HCC); however, its clinical efficacy is largely undermined by the acquisition of resistance. The aim of this study was to identify the key lncRNA involved in the regulation of the sorafenib response in HCC.
MATERIALS AND METHODS
A clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) single-guide RNA (sgRNA) synergistic activation mediator (SAM)-pooled lncRNA library was applied to screen for the key lncRNA regulated by sorafenib treatment. The role of the identified lncRNA in mediating the sorafenib response in HCC was examined in vitro and in vivo. The underlying mechanism was delineated by proteomic analysis. The clinical significance of the expression of the identified lncRNA was evaluated by multiplex immunostaining on a human HCC microtissue array.
RESULTS
CRISPR/Cas9 lncRNA library screening revealed that Linc01056 was among the most downregulated lncRNAs in sorafenib-resistant HCC cells. Knockdown of Linc01056 reduced the sensitivity of HCC cells to sorafenib, suppressing apoptosis in vitro and promoting tumour growth in mice in vivo. Proteomic analysis revealed that Linc01056 knockdown in sorafenib-treated HCC cells induced genes related to fatty acid oxidation (FAO) while repressing glycolysis-associated genes, leading to a metabolic switch favouring higher intracellular energy production. FAO inhibition in HCC cells with Linc01056 knockdown significantly restored sensitivity to sorafenib. Mechanistically, we determined that PPARα is the critical molecule governing the metabolic switch upon Linc01056 knockdown in HCC cells and indeed, PPARα inhibition restored the sorafenib response in HCC cells in vitro and HCC tumours in vivo. Clinically, Linc01056 expression predicted optimal overall and progression-free survival outcomes in HCC patients and predicted a better sorafenib response. Linc01056 expression indicated a low FAO level in HCC.
CONCLUSION
Our study identified Linc01056 as a critical epigenetic regulator and potential therapeutic target in the regulation of the sorafenib response in HCC.
Topics: Humans; Mice; Animals; Sorafenib; Carcinoma, Hepatocellular; RNA, Long Noncoding; Liver Neoplasms; RNA, Guide, CRISPR-Cas Systems; PPAR alpha; Proteomics; Cell Line, Tumor; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic
PubMed: 38582885
DOI: 10.1186/s12943-024-01988-y -
Frontiers in Immunology 2023T-cell-mediated autoimmune type 1 diabetes (T1D) is characterized by the immune-mediated destruction of pancreatic beta cells (β-cells). The increasing prevalence of... (Review)
Review
T-cell-mediated autoimmune type 1 diabetes (T1D) is characterized by the immune-mediated destruction of pancreatic beta cells (β-cells). The increasing prevalence of T1D poses significant challenges to the healthcare system, particularly in countries with struggling economies. This review paper highlights the multifaceted roles of Peroxisome Proliferator-Activated Receptors (PPARs) in the context of T1D, shedding light on their potential as regulators of immune responses and β-cell biology. Recent research has elucidated the intricate interplay between CD4+ T cell subsets, such as Tregs and Th17, in developing autoimmune diseases like T1D. Th17 cells drive inflammation, while Tregs exert immunosuppressive functions, highlighting the delicate balance crucial for immune homeostasis. Immunotherapy has shown promise in reinstating self-tolerance and restricting the destruction of autoimmune responses, but further investigations are required to refine these therapeutic strategies. Intriguingly, PPARs, initially recognized for their role in lipid metabolism, have emerged as potent modulators of inflammation in autoimmune diseases, particularly in T1D. Although evidence suggests that PPARs affect the β-cell function, their influence on T-cell responses and their potential impact on T1D remains largely unexplored. It was noted that PPARα is involved in restricting the transcription of IL17A and enhancing the expression of Foxp3 by minimizing its proteasomal degradation. Thus, antagonizing PPARs may exert beneficial effects in regulating the differentiation of CD4+ T cells and preventing T1D. Therefore, this review advocates for comprehensive investigations to delineate the precise roles of PPARs in T1D pathogenesis, offering innovative therapeutic avenues that target both the immune system and pancreatic function. This review paper seeks to bridge the knowledge gap between PPARs, immune responses, and T1D, providing insights that may revolutionize the treatment landscape for this autoimmune disorder. Moreover, further studies involving PPAR agonists in non-obese diabetic (NOD) mice hold promise for developing novel T1D therapies.
Topics: Mice; Animals; Diabetes Mellitus, Type 1; Mice, Inbred NOD; Autoimmune Diseases; Cell Differentiation; Inflammation; PPAR alpha
PubMed: 37928539
DOI: 10.3389/fimmu.2023.1292238 -
International Journal of Molecular... Oct 2021Social behavioral changes, including social isolation or loneliness, increase the risk for stress-related disorders, such as major depressive disorder, posttraumatic...
Social behavioral changes, including social isolation or loneliness, increase the risk for stress-related disorders, such as major depressive disorder, posttraumatic stress disorder (PTSD), and suicide, which share a strong neuroinflammatory etiopathogenetic component. The peroxisome-proliferator activated receptor (PPAR)-α, a newly discovered target involved in emotional behavior regulation, is a ligand-activated nuclear receptor and a transcription factor that, following stimulation by endogenous or synthetic ligands, may induce neuroprotective effects by modulating neuroinflammation, and improve anxiety and depression-like behaviors by enhancing neurosteroid biosynthesis. How stress affects epigenetic mechanisms with downstream effects on inflammation and emotional behavior remains poorly understood. We studied the effects of 4-week social isolation, using a mouse model of PTSD/suicide-like behavior, on hippocampal PPAR-α epigenetic modification. Decreased PPAR-α expression in the hippocampus of socially isolated mice was associated with increased levels of methylated cytosines of PPAR-α gene CpG-rich fragments and deficient neurosteroid biosynthesis. This effect was associated with increased histone deacetylases (HDAC)1, methyl-cytosine binding protein (MeCP)2 and decreased ten-eleven translocator (TET)2 expression, which favor hypermethylation. These alterations were associated with increased TLR-4 and pro-inflammatory markers (e.g., TNF-α,), mediated by NF-κB signaling in the hippocampus of aggressive mice. This study contributes the first evidence of stress-induced brain PPAR-α epigenetic regulation. Social isolation stress may constitute a risk factor for inflammatory-based psychiatric disorders associated with neurosteroid deficits, and targeting epigenetic marks linked to PPAR-α downregulation may offer a valid therapeutic approach.
Topics: Aggression; Animals; Behavior, Animal; Chromatin Assembly and Disassembly; CpG Islands; Disease Models, Animal; Disease Susceptibility; Epigenesis, Genetic; Gene Expression; Hippocampus; Inflammation; Inflammation Mediators; Male; Methylation; Mice; PPAR alpha; Promoter Regions, Genetic; Signal Transduction; Social Isolation; Stress, Psychological
PubMed: 34639019
DOI: 10.3390/ijms221910678 -
Autophagy Dec 2021Hepatic macroautophagy/autophagy and fatty acid metabolism are transcriptionally regulated by nuclear receptors (NRs); however, it is not known whether their...
Hepatic macroautophagy/autophagy and fatty acid metabolism are transcriptionally regulated by nuclear receptors (NRs); however, it is not known whether their transcriptional co-activators are involved in autophagy. We thus examined MED1 (mediator complex subunit 1), a key component of the Mediator Complex that directly interacts with NRs, on these processes. We found that knockdown (KD) in cultured hepatic cells decreased autophagy and mitochondrial activity that was accompanied by decreased transcription of genes involved in these processes. Lipophagy and fatty acid β-oxidation also were impaired. These effects also occurred after thyroid hormone stimulation, nutrient-replete or -deplete conditions, and in liver-specific KD ( LKD) mice under fed and fasting conditions. Together, these findings showed that played a key role in hepatic autophagy, mitochondria function, and lipid metabolism under these conditions. Additionally, we identified downregulated hepatic genes in LKD mice, and subjected them to ChIP Enrichment Analysis. Our findings showed that the transcriptional activity of several NRs and transcription factors (TFs), including PPARA and FOXO1, likely were affected by LKD. Finally, expression and autophagy also were decreased in two mouse models of nonalcoholic fatty liver disease (NAFLD) suggesting that decreased may contribute to hepatosteatosis. In summary, plays an essential role in regulating hepatic autophagy and lipid oxidation during different hormonal and nutrient conditions. Thus, may serve as an integrator of multiple transcriptional pathways involved in these metabolic processes. BAF: bafilomycin A; db/db mice; mice; ECAR: extracellular acidification rate; KD: knockdown; MED1: mediator complex subunit 1; NAFLD: nonalcoholic fatty liver disease; OCR: oxygen consumption rate; PPARA/PPARα: peroxisomal proliferator activated receptor alpha; TF: transcription factor; TFEB: transcription factor EB; tf-LC3: tandem fluorescence RFP-GFP-LC3; TG: triglyceride; TH: Thyroid hormone; TR: thyroid hormone receptors; V-ATPase: vacuolar-type H-ATPase; WDF: Western diet with 15% fructose in drinking water.
Topics: Animals; Autophagy; Lipid Metabolism; Liver; Mediator Complex Subunit 1; Mice; Non-alcoholic Fatty Liver Disease; PPAR alpha
PubMed: 33734012
DOI: 10.1080/15548627.2021.1899691 -
Cell Communication and Signaling : CCS Jan 2023Phosphorus commonly reduces lipid deposition in the vertebrates. However, the underlying mechanisms involved in the process remain unclear.
BACKGROUND
Phosphorus commonly reduces lipid deposition in the vertebrates. However, the underlying mechanisms involved in the process remain unclear.
METHODS
Yellow catfish were given three experimental diets with dietary phosphate levels of 3.22, 6.47 and 7.99 g Pi kg, respectively, for 8 weeks. The contents of triglyceride, non-esterified free fatty acids, adenosine triphosphate, nicotinamide adenine dinucleotide, nicotinamide adenine dinucleotide, enzymatic activities, mRNA and protein expression were determined in the intestinal tissues. Hematoxylin and eosin, Oil Red O staining, and transmission electron microscope were performed for intestinal tissues. Primary intestinal epithelial cells were isolated from yellow catfish intestine. Western blot analysis, Immunoprecipitation assays, Immunofluorescence staining, and RNA extraction and quantitative real-time PCR were decided. Luciferase reporter assays and electrophoretic mobility shift assay were used to evaluate the function of Sirt3, PPARα and Lcad promoters.
RESULTS
High dietary phosphate intake activated intestinal phosphate absorption and excretion, and reduced lipid deposition through increasing lipolysis in the intestine. Moreover, phosphate incubation increased the mRNA and protein expression of krüppel like factor 4 (klf4), silent mating-type information regulation 2 homolog 3 (sirt3), peroxisome proliferator activated receptor alpha (pparα) and long chain acyl-CoA dehydrogenase (lcad) in the intestinal epithelial cells (IECs), and klf4 knockdown attenuated the phosphate-induced increase of protein levels of Sirt3, Pparα and Lcad. Further investigation found that Klf4 overexpression increased the activity of sirt3 and pparα promoters, which in turn reduced the acetylation and protein level of Lcad.
CONCLUSION
Dietary Pi excess induced lipid degradation by the activation of the Klf4-Sirt3/Pparα-Lcad pathway in the intestine and primary IECs. Video Abstract.
Topics: Animals; Lipids; Lipolysis; Oxidation-Reduction; PPAR alpha; RNA, Messenger; Sirtuin 3; Catfishes
PubMed: 36624473
DOI: 10.1186/s12964-022-01008-w -
Cells Dec 2022Microglial activation and subsequent pathological neuroinflammation contribute to diabetic retinopathy (DR). However, the underlying mechanisms of microgliosis, and...
Microglial activation and subsequent pathological neuroinflammation contribute to diabetic retinopathy (DR). However, the underlying mechanisms of microgliosis, and means to effectively suppress pathological microgliosis, remain incompletely understood. Peroxisome proliferator-activated receptor alpha (PPARα) is a transcription factor that regulates lipid metabolism. The present study aimed to determine if PPARα affects pathological microgliosis in DR. In global mice, retinal microglia exhibited decreased structural complexity and enlarged cell bodies, suggesting microglial activation. Microglia-specific conditional (PCKO) mice showed decreased retinal thickness as revealed by optical coherence tomography. Under streptozotocin (STZ)-induced diabetes, diabetic PCKO mice exhibited decreased electroretinography response, while diabetes-induced retinal dysfunction was alleviated in diabetic microglia-specific -transgenic (PCTG) mice. Additionally, diabetes-induced retinal pericyte loss was exacerbated in diabetic PCKO mice and alleviated in diabetic PCTG mice. In cultured microglial cells with the diabetic stressor 4-HNE, metabolic flux analysis demonstrated that ablation caused a metabolic shift from oxidative phosphorylation to glycolysis. deficiency also increased microglial STING and TNF-α expression. Taken together, these findings revealed a critical role for PPARα in pathological microgliosis, neurodegeneration, and vascular damage in DR, providing insight into the underlying molecular mechanisms of microgliosis in this context and suggesting microglial PPARα as a potential therapeutic target.
Topics: Animals; Mice; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Microglia; PPAR alpha; Retina
PubMed: 36497130
DOI: 10.3390/cells11233869 -
Journal of Applied Oral Science :... 2022Inflammation-related immune responses and bone metabolism lead to extensive tooth loss in periodontitis.. This study aims to investigate the effect of peroxisome...
OBJECTIVE
Inflammation-related immune responses and bone metabolism lead to extensive tooth loss in periodontitis.. This study aims to investigate the effect of peroxisome proliferator-activated receptor (PPAR) alpha agonist anti-inflammatory treatment in vitro and in ligature-induced experimental periodontitis in vivo .
METHODOLOGY
Splenocytes were isolated from C57BL/6J mice and cultured for 48 hours under the following conditions: control, P. gingivalis lipopolysaccharide (LPS) (1 µg/ml); experimental, LPS (1 µg/ml) + PPARα agonist (fenofibrate) at 1, 10, 50, 100 µM. MRNA and secreted protein levels of TNF-α expression were detected by RT-qPCR and ELISA, respectively. Silk ligatures (7-0) were tied around maxillary second molars of C57BL/6J mice for two weeks. Optimized doses of fenofibrate (50 µM) and vehicle control were injected into the contralateral side of the palatal gingiva on days three, six, and nine. At day 14, bone resorption, osteoclastogenesis, and gingival mRNA expression levels of TNF-α, IL-1β, IL-6, and RANKL/OPG were measured by micro-computed tomography, Tartrate-resistant acid phosphatase (TRAP) staining, and Real-time quantitative PCR, respectively.
RESULTS
TNF-α expression in cultured spleen cells were significantly increased in the presence of LPS, when compared with the control group, and significantly reduced by fenofibrate treatment in a dose-dependent manner from 1-100 µM (p<0.05). Gingival mRNA levels of TNF-α, IL-1β, IL-6, and the ratio of RANKL/OPG, were significantly decreased after injection of fenofibrate, when compared to the control side (p<0.05). Periodontal bone loss and TRAP positive cell formation were significantly decreased on the side with an injection of fenofibrate, as compared to the control side (p<0.05).
CONCLUSIONS
An anti-inflammatory treatment, PPARα agonist, inhibited inflammation and periodontal bone loss in ligature-induced experimental periodontitis.
Topics: Alveolar Bone Loss; Animals; Mice; Mice, Inbred C57BL; PPAR alpha; Periodontitis; X-Ray Microtomography
PubMed: 35293424
DOI: 10.1590/1678-7757-2021-0648 -
The Journal of Biological Chemistry Jul 2023Maintenance of metabolic homeostasis is secured by metabolite-sensing systems, which can be overwhelmed by constant macronutrient surplus in obesity. Not only the uptake...
Maintenance of metabolic homeostasis is secured by metabolite-sensing systems, which can be overwhelmed by constant macronutrient surplus in obesity. Not only the uptake processes but also the consumption of energy substrates determine the cellular metabolic burden. We herein describe a novel transcriptional system in this context comprised of peroxisome proliferator-activated receptor alpha (PPARα), a master regulator for fatty acid oxidation, and C-terminal binding protein 2 (CtBP2), a metabolite-sensing transcriptional corepressor. CtBP2 interacts with PPARα to repress its activity, and the interaction is enhanced upon binding to malonyl-CoA, a metabolic intermediate increased in tissues in obesity and reported to suppress fatty acid oxidation through inhibition of carnitine palmitoyltransferase 1. In line with our preceding observations that CtBP2 adopts a monomeric configuration upon binding to acyl-CoAs, we determined that mutations in CtBP2 that shift the conformational equilibrium toward monomers increase the interaction between CtBP2 and PPARα. In contrast, metabolic manipulations that reduce malonyl-CoA decreased the formation of the CtBP2-PPARα complex. Consistent with these in vitro findings, we found that the CtBP2-PPARα interaction is accelerated in obese livers while genetic deletion of CtBP2 in the liver causes derepression of PPARα target genes. These findings support our model where CtBP2 exists primarily as a monomer in the metabolic milieu of obesity to repress PPARα, representing a liability in metabolic diseases that can be exploited to develop therapeutic approaches.
Topics: Humans; Fatty Acids; Liver; Obesity; PPAR alpha; Alcohol Oxidoreductases; Co-Repressor Proteins; Allosteric Regulation
PubMed: 37286039
DOI: 10.1016/j.jbc.2023.104890