Intermittent hypoxia exacerbates metabolic dysfunction-associated fatty liver disease by aggravating hepatic copper deficiency-induced ferroptosis.

Intermittent hypoxia (IH) is an independent risk factor for metabolic dysfunction-associated fatty liver disease (MAFLD). Copper deficiency can disrupt redox homeostasis, iron, and lipid metabolism. Here, we investigated whether hepatic copper deficiency plays a role in IH-associated MAFLD and explored the underlying mechanism(s). Male C57BL/6 mice were fed a western-type diet with adequate copper (CuA) or marginally deficient copper (CuD) and were exposed separately to room air (RA) or IH. Hepatic histology, plasma biomarkers, copper-iron status, and oxidative stress were assessed. An in vitro HepG2 cell lipotoxicity model and proteomic analysis were used to elucidate the specific targets involved. We observed that there were no differences in hepatic phenotypes between CuA-fed and CuD-fed mice under RA. However, in IH exposure, CuD-fed mice showed more pronounced hepatic steatosis, liver injury, and oxidative stress than CuA-fed mice. IH induced copper accumulation in the brain and heart and exacerbated hepatic copper deficiency and secondary iron deposition. In vitro, CuD-treated cells with IH exposure showed elevated levels of lipid accumulation, oxidative stress, and ferroptosis susceptibility. Proteomic analysis identified 360 upregulated and 359 downregulated differentially expressed proteins between CuA and CuD groups under IH; these proteins were mainly enriched in citrate cycle, oxidative phosphorylation, fatty acid metabolism, the peroxisome proliferator-activated receptor (PPAR)α pathway, and ferroptosis. In IH exposure, CuD significantly upregulated the ferroptosis-promoting factor arachidonyl-CoA synthetase long chain family member (ACSL)4. ACSL4 knockdown markedly eliminated CuD-induced ferroptosis and lipid accumulation in IH exposure. In conculsion, IH can lead to reduced hepatic copper reserves and secondary iron deposition, thereby inducing ferroptosis and subsequent MAFLD progression. Insufficient dietary copper may worsen IH-associated MAFLD.

Super-enhancer-driven LncRNA PPARα-seRNA exacerbates glucolipid metabolism and diabetic cardiomyopathy via recruiting KDM4B.

OBJECTIVE: Aberrant glucolipid metabolism in the heart is a characteristic factor in diabetic cardiomyopathy (DbCM). Super-enhancers-driven noncoding RNAs (seRNAs) are emerging as powerful regulators in the progression of cardiac diseases. However, the functions of seRNAs in DbCM have not been fully elucidated. METHODS: Super enhancers and their associated seRNAs were screened and identified by H3K27ac ChIP-seq data in the Encyclopedia of DNA Elements (ENCODE) dataset. A dual-luciferase reporter assay was performed to analyze the function of super-enhancers on the transcription of peroxisome proliferator-activated receptor α-related seRNA (PPARα-seRNA). A DbCM mouse model was established using db/db leptin receptor-deficient mice. Adeno-associated virus serotype 9-seRNA (AAV9-seRNA) was injected via the tail vein to evaluate the role of seRNA in DbCM. The underlying mechanism was explored through RNA pull-down, RNA and chromatin immunoprecipitation, and chromatin isolation by RNA purification. RESULTS: PPARα-seRNA was regulated by super-enhancers and its levels were increased in response to high glucose and palmitic acid stimulation in cardiomyocytes. Functionally, PPARα-seRNA overexpression aggravated lipid deposition, reduced glucose uptake, and repressed energy production. In contrast, PPARα-seRNA knockdown ameliorated metabolic disorder in vitro. In vivo, overexpression of PPARα-seRNA exacerbated cardiac metabolic disorder and deteriorated cardiac dysfunction, myocardial fibrosis, and hypertrophy in DbCM. Mechanistically, PPARα-seRNA bound to the histone demethylase KDM4B (Lysine-specific demethylase 4B) and decreased H3K9me3 levels in the promoter region of PPARα, ultimately enhancing its transcription. CONCLUSIONS: Our study revealed the pivotal function of a super-enhancer-driven long noncoding RNA (lncRNA), PPARα-seRNA, in the deterioration of cardiac function and the exacerbation of metabolic abnormalities in diabetic cardiomyopathy, which recruited KDM4B to the promoter region of PPARα and repression of its transcription. This suggests a promising therapeutic strategy for the treatment of DbCM.

(+)Alpha-Lipoic Acid Regulates Lipid Metabolism Gene Expression and Lipidic Profile in a Cellular Model of Fatty Acid Overload.

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is a prevalent condition characterized by hepatic fat accumulation, often progressing to severe liver injury, for which approved treatments are currently lacking. This study explores the potential therapeutic impact of alpha-lipoic acid (ALA), a natural compound crucial in lipid metabolism, on NAFLD using an in vitro model. METHODS: HepG2 cells were treated with a palmitic acid:oleic acid (PA:OA) mixture, representing a cellular model of steatosis. Subsequent treatment with ALA at concentrations of 1 µM and 5 µM aimed to evaluate its effects on lipid content and metabolism. Real-time polymerase chain reaction (PCR), BODIPY staining, cytofluorimetric analysis, and lipidomics were used to assess gene expression, lipid droplet accumulation, and fatty acid profiles. RESULTS: Our results showed that ALA significantly reduced lipid droplets in PA:OA-treated HepG2 cells, with a concentration-dependent effect. Analysis of fatty acid profiles demonstrated a decrease in palmitic acid levels with ALA treatment, while oleic acid reduction was observed only at the higher concentration. Moreover, ALA modulated the expression of genes involved in cholesterol biosynthesis and low-density lipoprotein (LDL) metabolism, indicating a potential role in lipid homeostasis. Further insights into molecular mechanisms revealed that ALA modulated peroxisome proliferator activated receptors (PPARs), specifically PPAR-alpha and PPAR-gamma, involved in fatty acid metabolism and insulin sensitivity. Finally, ALA counteracted the overexpression of thermogenic genes induced by exogenous fatty acids, suggesting a regulatory role in energy dissipation pathways. CONCLUSION: In conclusion, this study highlights ALA as a therapeutic agent in mitigating lipid accumulation and dysregulation in NAFLD.

PPARα phosphorylation regulates colorectal tumor immune escape.

A high level of PD-L1 in cancer cells promotes tumor immune escape and inhibits tumor immunotherapy. Although PD-L1 gene expression is upregulated by multiple pathways, its gene transcriptional repression is still unclear. Here we found that loss of PPARα, one of the peroxisome-proliferator-activated receptors (PPARs) family members, promoted colorectal tumor immune escape. Mechanistically, PPARα directly bound to the PD-L1 promoter resulting in its gene transcriptional repression, which in turn increased T cell activity, and PPARα agonist enhanced this event. However, ERK induced PPARα-S12 phosphorylation leading to blockade of PPARα-mediated PD-L1 transcriptional repression, and the combination of ERK inhibitor with PPARα agonist significantly inhibited tumor immune escape. These findings suggest that the ERK-PPARα pathway inhibited PD-L1 gene transcriptional repression and promoted colorectal tumor immune escape.

Endogenous activation of peroxisome proliferator-activated receptor-α in proximal tubule cells in counteracting phosphate toxicity.

Increased dietary phosphate consumption intensifies renal phosphate burden. Several mechanisms for phosphate-induced renal tubulointerstitial fibrosis have been reported. Considering the dual nature of phosphate as both a potential renal toxin and an essential nutrient for the body, kidneys may possess inherent protective mechanisms against phosphate overload, rather than succumbing solely to injury. However, there is limited understanding of such mechanisms. To identify these mechanisms, we conducted single-cell RNA sequencing (scRNA-seq) analysis of the kidneys of control and dietary phosphate-loaded (Phos) mice at a time point when the Phos group had not yet developed tubulointerstitial fibrosis. scRNA-seq analysis identified the highest number of differentially expressed genes in the clusters belonging to proximal tubular epithelial cells (PTECs). Based on these differentially expressed genes, in silico analyses suggested that the Phos group activated peroxisome proliferator-activated receptor-α (PPAR-α) and fatty acid ß-oxidation (FAO) in the PTECs. This activation was further substantiated through various experiments, including the use of an FAO activity visualization probe. Compared with wild-type mice, Ppara knockout mice exhibited exacerbated tubulointerstitial fibrosis in response to phosphate overload. Experiments conducted with cultured PTECs demonstrated that activation of the PPAR-α/FAO pathway leads to improved cellular viability under high-phosphate conditions. The Phos group mice showed a decreased serum concentration of free fatty acids, which are endogenous PPAR-α agonists. Instead, experiments using cultured PTECs revealed that phosphate directly activates the PPAR-α/FAO pathway. These findings indicate that noncanonical metabolic reprogramming via endogenous activation of the PPAR-α/FAO pathway in PTECs is essential to counteract phosphate toxicity.NEW & NOTEWORTHY This study revealed the activation of peroxisome proliferator-activated receptor-α and fatty acid ß-oxidation in proximal tubular epithelial cells as an endogenous mechanism to protect the kidney from phosphate toxicity. These findings highlight noncanonical metabolic reprogramming as a potential target for suppressing phosphate toxicity in the kidneys.

Counteracting TGM2 by a Fibroin peptide ameliorated Adriamycin-induced nephropathy via regulation of lipid metabolism through PANX1-PPAR α/PANK1 pathway.

Peptide drug discovery for the treatment of chronic kidney disease (CKD) has attracted much attention in recent years due to the urge to find novel drugs and mechanisms to delay the progression of the disease. In this study, we identified a novel short peptide (named YR-7, primary sequence 'YEVEDYR') from the natural Fibroin protein, and demonstrated that it significantly alleviated pathological renal changes in ADR-induced nephropathy. PANX1 was identified as the most notably upregulated component by RNA-sequencing. Further analysis showed that YR-7 alleviated the accumulation of lipid droplets via regulation of the lipid metabolism-related proteins PPAR α and PANK1. Using chemical proteomics, fluorescence polarization, microscale thermophoresis, surface plasmon resonance, and molecular docking, YR-7 was proven to directly bind to ß-barrel domains of TGM2 protein to inhibit lipid accumulation. TGM2 knockdown in vivo increased the protein levels of PPAR α and PANK1 while decreased the levels of fibrotic-related proteins to alleviate nephropathy. In vitro, overexpression TGM2 reversed the protective effects of YR-7. Co-immunoprecipitation indicated that TGM2 interacted with PANX1 to promote lipid deposition, and pharmacological inhibition or knockdown of PANX1 decreased the levels of PPAR α and PANK1 induced by ADR. Taken together, our findings revealed that TGM2-PANX1 interaction in promoting lipid deposition may be a new signaling in promoting ADR-induced nephropathy. And a novel natural peptide could ameliorate renal fibrosis through TGM2-PANX1-PPAR α/PANK1 pathway, which highlight the potential of it in the treatment of CKD.

Ketogenic diet time-dependently prevents NAFLD through upregulating the expression of antioxidant protein metallothionein-2.

BACKGROUND & AIMS: The past few decades have witnessed a rapid growth in the prevalence of nonalcoholic fatty liver disease (NAFLD). While the ketogenic diet (KD) is considered for managing NAFLD, the safety and efficacy of the KD on NAFLD has been a controversial topic. Here, we aimed to investigate the effect of KD of different durations on metabolic endpoints in mice with NAFLD and explore the underlying mechanisms. METHODS: NAFLD mice were fed with KD for 1, 2, 4 and 6 weeks, respectively. The blood biochemical indexes (blood lipids, AST, ALT and etc.) and liver fat were measured. The LC-MS/MS based proteomic analysis was performed on liver tissues. Metallothionein-2 (MT2) was knocked down with adeno-associated virus (AAV) or small interfering RNA (siRNA) in NAFLD mice and AML-12 cells, respectively. H&E, BODIPY and ROS staining were performed to examine lipid deposition and oxidative stress. Furthermore, MT2 protein levels, nucleus/cytoplasm distribution and DNA binding activity of peroxisome proliferators-activated receptors α (PPARα) were evaluated. RESULTS: KD feeding for 2 weeks showed the best improvement on NAFLD phenotype. Proteomic analysis revealed that MT2 was a key candidate for different metabolic endpoints of NAFLD affected by different durations of KD feeding. MT2 knockdown in NAFLD mice blocked the effects of 2 weeks of KD feeding on HFD-induced steatosis. In mouse primary hepatocytes and AML-12 cells, MT2 protein levels were induced by ß-hydroxybutyric acid (ß-OHB). MT2 Knockdown blunted the effects of ß-OHB on alleviating PA-induced lipid deposition. Mechanistically, 2 weeks of KD or ß-OHB treatment reduced oxidative stress and upregulated the protein levels of MT2 in nucleus, which subsequently increased its DNA binding activity and PPARα protein expression. CONCLUSIONS: Collectively, these findings indicated that KD feeding prevented NAFLD in a time dependent manner and MT2 is a potential target contributing to KD improvement on steatosis.

Triclosan administration to humanized UDP-glucuronosyltransferase 1 neonatal mice induces UGT1A1 through a dependence on PPARα and ATF4.

Triclosan (TCS) is an antimicrobial toxicant found in a myriad of consumer products and has been detected in human tissues, including breastmilk. We have evaluated the impact of lactational TCS on UDP-glucuronosyltransferase 1A1 (UGT1A1) expression and bilirubin metabolism in humanized UGT1 (hUGT1) neonatal mice. In hUGT1 mice, expression of the hepatic UGT1A1 gene is developmentally delayed resulting in elevated total serum bilirubin (TSB) levels. We found that newborn hUGT1 mice breastfed or orally treated with TCS presented lower TSB levels along with induction of hepatic UGT1A1. Lactational and oral treatment by gavage with TCS leads to the activation of hepatic nuclear receptors constitutive androstane receptor (CAR), peroxisome proliferator-activated receptor alpha (PPARα), and stress sensor, activating transcription factor 4 (ATF4). When CAR-deficient hUGT1 mice (hUGT1/Car-/-) were treated with TCS, TSB levels were reduced with a robust induction of hepatic UGT1A1, leaving us to conclude that CAR is not tied to UGT1A1 induction. Alternatively, when PPARα-deficient hUGT1 mice (hUGT1/Pparα-/-) were treated with TCS, hepatic UGT1A1 was not induced. Additionally, we had previously demonstrated that TCS is a potent inducer of ATF4, a transcriptional factor linked to the integrated stress response. When ATF4 was deleted in liver of hUGT1 mice (hUGT1/Atf4ΔHep) and these mice treated with TCS, we observed superinduction of hepatic UGT1A1. Oxidative stress genes in livers of hUGT1/Atf4ΔHep treated with TCS were increased, suggesting that ATF4 protects liver from excessive oxidative stress. The increase oxidative stress may be associated with superinduction of UGT1A1. The expression of ATF4 in neonatal hUGT1 hepatic tissue may play a role in the developmental repression of UGT1A1.

Oxidative stress in peroxisomes induced by androgen receptor inhibition through peroxisome proliferator-activated receptor promotes enzalutamide resistance in prostate cancer.

Androgen receptor (AR)-targeting therapy induces oxidative stress in prostate cancer. However, the mechanism of oxidative stress induction by AR-targeting therapy remains unclear. This study investigated the mechanism of oxidative stress induction by AR-targeting therapy, with the aim to develop novel therapeutics targeting oxidative stress induced by AR-targeting therapy. Intracellular reactive oxygen species (ROS) was examined by fluorescence microscopy and flow cytometry analysis. The effects of silencing gene expression and small molecule inhibitors on gene expression and cytotoxic effects were examined by quantitative real-time PCR and cell proliferation assay. ROS induced by androgen depletion co-localized with peroxisomes in prostate cancer cells. Among peroxisome-related genes, PPARA was commonly induced by AR inhibition and involved in ROS production via PKC signaling. Inhibition of PPARα by specific siRNA and a small molecule inhibitor suppressed cell proliferation and increased cellular sensitivity to the antiandrogen enzalutamide in prostate cancer cells. This study revealed a novel pathway by which AR inhibition induced intracellular ROS mainly in peroxisomes through PPARα activation in prostate cancer. This pathway is a promising target for the development of novel therapeutics for prostate cancer in combination with AR-targeting therapy such as antiandrogen enzalutamide.

CBFA2T3 Is PPARA Sensitive and Attenuates Fasting-Induced Lipid Accumulation in Mouse Liver.

Peroxisome proliferator-activated receptor alpha (PPARA) is a ligand-activated transcription factor that is a key mediator of lipid metabolism and metabolic stress in the liver. Accumulating evidence shows that PPARA regulates the expression of various protein coding and non-coding genes that modulate metabolic stress in the liver. CBFA2/RUNX1 partner transcriptional co-repressor 3 (CBFA2T3) is a DNA-binding transcription factor that belongs to the myeloid translocation gene family. Many studies have shown that CBFA2T3 is associated with acute myeloid leukemia. Especially, CBFA2T3-GLIS2 fusion is a chimeric oncogene associated with a poor survival rate in pediatric acute megakaryocytic leukemia. A previous study identified that PPARA activation promoted Cbfa2t3 induction in liver and that Cbfa2t3 may have a modulatory role in metabolic stress. However, the effect of CBFA2T3 gene expression on metabolic stress is not understood. In this study, the PPARA ligand WY14643 activated Cbfa2t3 expression in mouse liver. Glucose tolerance test and insulin tolerance test data showed that insulin resistance is increased in Cbfa2t3-/- mice compared to Cbfa2t3+/+ mice. Hepatic CBFA2T3 modulates heat shock protein family A member 1b and carbonic anhydrase 5a expression. Histology analysis revealed lipid droplet and lipid accumulation in the liver of fasting Cbfa2t3-/- mice but not Cbfa2t3+/+ mice. The expression of lipid accumulation-related genes, such as Cd36, Cidea, and Fabp1, was increased in the liver of fasting Cbfa2t3-/- mice. Especially, basal expression levels of Cidea mRNA were elevated in the liver of Cbfa2t3-/- mice compared to Cbfa2t3+/+ mice. Much higher induction of Cidea mRNA was seen in the liver of Cbfa2t3-/- mice after WY14643 administration. These results indicate that hepatic CBFA2T3 is a PPARA-sensitive gene that may modulate metabolic stress in mouse liver.

PPAR-α inhibits DHEA-induced ferroptosis in granulosa cells through upregulation of FADS2.

BACKGROUND: Polycystic ovary syndrome (PCOS), a prevalent endocrine disorder among women of reproductive age, is characterized by disturbances in hormone levels and ovarian dysfunction. Ferroptosis, a unique form of regulated cell death characterized by iron-dependent lipid peroxidation. Emerging evidence indicates that ferroptosis may have a significant role in the pathogenesis of PCOS, highlighting the importance of studying this mechanism to better understand the disorder and potentially develop novel therapeutic interventions. METHODS: To create an in vivo PCOS model, mice were injected with dehydroepiandrosterone (DHEA) and the success of the model was confirmed through further assessments. Ferroptosis levels were evaluated through detecting ferroptosis-related indicators. Ferroptosis-related genes were found through bioinformatic analysis and identified by experiments. An in vitro PCOS model was also established using DHEA treated KGN cells. The molecular binding relationship was confirmed using a chromatin immunoprecipitation (ChIP) assay. RESULTS: In PCOS model, various ferroptosis-related indicators such as MDA, Fe2+, and lipid ROS showed an increase, while GSH, GPX4, and TFR1 exhibited a decrease. These findings indicate an elevated level of ferroptosis in the PCOS model. The ferroptosis-related gene FADS2 was identified and validated. FADS2 and PPAR-α were shown to be highly expressed in ovarian tissue and primary granulosa cells (GCs) of PCOS mice. Furthermore, the overexpression of both FADS2 and PPAR-α in KGN cells effectively suppressed the DHEA-induced increase in ferroptosis-related indicators (MDA, Fe2+, and lipid ROS) and the decrease in GSH, GPX4, and TFR1 levels. The ferroptosis agonist erastin reversed the suppressive effect, suggesting the involvement of ferroptosis in this process. Additionally, the FADS2 inhibitor SC26196 was found to inhibit the effect of PPAR-α on ferroptosis. Moreover, the binding of PPAR-α to the FADS2 promoter region was predicted and confirmed. This indicates the regulatory relationship between PPAR-α and FADS2 in the context of ferroptosis. CONCLUSIONS: Our study indicates that PPAR-α may have an inhibitory effect on DHEA-induced ferroptosis in GCs by enhancing the expression of FADS2. This discovery provides valuable insights into the pathophysiology and potential therapeutic targets for PCOS.

MicroRNA-144-3p Inhibits Host Lipid Catabolism and Autophagy by Targeting PPARα and ABCA1 During Mycobacterium Tuberculosis Infection.

MicroRNA-mediated metabolic reprogramming recently has been identified as an important strategy for Mycobacterium tuberculosis (Mtb) to evade host immune responses. However, it is unknown what role microRNA-144-3p (miR-144-3p) plays in cellular metabolism during Mtb infection. Here, we report the meaning of miR-144-3p-mediated lipid accumulation for Mtb-macrophage interplay. Mtb infection was shown to upregulate the expression of miR-144-3p in macrophages. By targeting peroxisome proliferator-activated receptor α (PPARα) and ATP-binding cassette transporter A1 (ABCA1), miR-144-3p overexpression promoted lipid accumulation and bacterial survival in Mtb-infected macrophages, while miR-144-3p inhibition had the opposite effect. Furthermore, reprogramming of host lipid metabolism by miR-144-3p suppressed autophagy in response to Mtb infection. Our findings uncover that miR-144-3p regulates host metabolism and immune responses to Mtb by targeting PPARα and ABCA1, suggesting a potential host-directed tuberculosis therapy by targeting the interface of miRNA and lipid metabolism.

Crosstalk interactions between transcription factors ERRα and PPARα assist PPARα-mediated gene expression.

OBJECTIVE: The peroxisome proliferator-activated receptor α (PPARα) is a transcription factor driving target genes involved in fatty acid ß-oxidation. To what extent various PPARα interacting proteins may assist its function as a transcription factor is incompletely understood. An ORFeome-wide unbiased mammalian protein-protein interaction trap (MAPPIT) using PPARα as bait revealed a PPARα-ligand-dependent interaction with the orphan nuclear receptor estrogen-related receptor α (ERRα). The goal of this study was to characterize the nature of the interaction in depth and to explore whether it was of physiological relevance. METHODS: We used orthogonal protein-protein interaction assays and pharmacological inhibitors of ERRα in various systems to confirm a functional interaction and study the impact of crosstalk mechanisms. To characterize the interaction surfaces and contact points we applied a random mutagenesis screen and structural overlays. We pinpointed the extent of reciprocal ligand effects of both nuclear receptors via coregulator peptide recruitment assays. On PPARα targets revealed from a genome-wide transcriptome analysis, we performed an ERRα chromatin immunoprecipitation analysis on both fast and fed mouse livers. RESULTS: Random mutagenesis scanning of PPARα's ligand-binding domain and coregulator profiling experiments supported the involvement of (a) bridging coregulator(s), while recapitulation of the interaction in vitro indicated the possibility of a trimeric interaction with RXRα. The PPARα·ERRα interaction depends on 3 C-terminal residues within helix 12 of ERRα and is strengthened by both PGC1α and serum deprivation. Pharmacological inhibition of ERRα decreased the interaction of ERRα to ligand-activated PPARα and revealed a transcriptome in line with enhanced mRNA expression of prototypical PPARα target genes, suggesting a role for ERRα as a transcriptional repressor. Strikingly, on other PPARα targets, including the isolated PDK4 enhancer, ERRα behaved oppositely. Chromatin immunoprecipitation analyses demonstrate a PPARα ligand-dependent ERRα recruitment onto chromatin at PPARα-binding regions, which is lost following ERRα inhibition in fed mouse livers. CONCLUSIONS: Our data support the coexistence of multiple layers of transcriptional crosstalk mechanisms between PPARα and ERRα, which may serve to finetune the activity of PPARα as a nutrient-sensing transcription factor.

Molecular Mechanisms of Fucoxanthin in Alleviating Lipid Deposition in Metabolic Associated Fatty Liver Disease.

Metabolic-associated fatty liver disease (MAFLD) is witnessing a global surge; however, it still lacks effective pharmacological interventions. Fucoxanthin, a natural bioactive metabolite derived from marine brown algae, exhibits promising pharmacological functions, particularly in ameliorating metabolic disorders. However, the mechanisms underlying its therapeutic efficacy in addressing MAFLD remain elusive. Our present findings indicated that fucoxanthin significantly alleviated palmitic acid (PA)-induced hepatic lipid deposition in vitro and obesity-induced hepatic steatosis in ob/ob mice. Moreover, at both the protein and transcriptional levels, fucoxanthin effectively increased the expression of PPARα and CPT1 (involved in fatty acid oxidation) and suppressed FASN and SREBP1c (associated with lipogenesis) in both PA-induced HepG2 cells and hepatic tissues in ob/ob mice. This modulation was accompanied by the activation of AMPK. The capacity of fucoxanthin to improve hepatic lipid deposition was significantly attenuated when utilizing the AMPK inhibitor or siRNA-mediated AMPK silencing. Mechanistically, fucoxanthin activates AMPK, subsequently regulating the KEAP1/Nrf2/ARE signaling pathway to exert antioxidative effects and stimulating the PGC1α/NRF1 axis to enhance mitochondrial biogenesis. These collective actions contribute to fucoxanthin's amelioration of hepatic steatosis induced by metabolic perturbations. These findings offer valuable insights into the prospective utilization of fucoxanthin as a therapeutic strategy for managing MAFLD.

Hepatitis B virus X protein promotes tumor glycolysis by downregulating lncRNA OIP5-AS1/HKDC1 in HCC.

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality worldwide, with Hepatitis B virus (HBV) infection being the leading cause. This study aims to investigate the role of HBV in HCC pathogenesis involving glucose metabolism. Long non-coding RNA (lncRNA) OIP5-AS1 was significantly downregulated in HBV-positive HCC patients, and its low expression indicated a poor prognosis. This lncRNA was primarily localized in the cytoplasm, acting as a tumor suppressor. HBV protein X (HBx) repressed OIP5-AS1 expression by inhibiting a ligand-activated transcriptional factor peroxisome proliferator-activated receptor α (PPARα). Furthermore, mechanistic studies revealed that OIP5-AS1 inhibited tumor growth by suppressing Hexokinase domain component 1 (HKDC1)-mediated glycolysis. The expression of HKDC1 could be enhanced by transcriptional factor sterol regulatory element-binding protein 1 (SREBP1). OIP5-AS1 facilitated the ubiquitination and degradation of SREBP1 to suppress HKDC1 transcription, which inhibited glycolysis. The results suggest that lncRNA OIP5-AS1 plays an anti-oncogenic role in HBV-positive HCC via the HBx/OIP5-AS1/HKDC1 axis, providing a promising diagnostic marker and therapeutic target for HBV-positive HCC patients.

Loss of lncRNA LINC01056 leads to sorafenib resistance in HCC.

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.

[Gualou Xiebai Banxia Decoction treats type 2 diabetes mellitus combined with acute myocardial infarction via chemerin/ CMKLR1/PPARα signaling pathway].

This study aims to investigate the effects of Gualou Xiebai Banxia Decoction(GXBD) on type 2 diabetes mellitus(T2DM) combined with acute myocardial infarction(AMI) in rats via chemerin/chemokine-like receptor 1(CMKLR1)/peroxisome proliferator-activated receptor α(PPARα) signaling pathway, and to explore the mechanism of GXBD in alleviating glucose and lipid metabolism disorders. The SD rats were randomized into control, model, positive control, and low-and high-dose GXBD groups. The rat model of T2DM was established by administration with high-fat emulsion(HFE) by gavage and intraperitoneal injection with streptozotocin, and then coronary artery ligation was performed to induce AMI. The control and model groups were administrated with the equal volume of normal saline, and other groups were administrated with corresponding drugs by gavage. Changes in relevant metabolic indicators were assessed by ELISA and biochemical assays, and the protein levels of chemerin, CMKLR1, and PPARα in the liver, abdominal fat, and heart were determined by Western blot. The results showed that GXBD alleviated the myocardial damage and reduced the levels of blood lipids, myocardial enzymes, and inflammatory cytokines, while it did not lead to significant changes in blood glucose. Compared with the model group, GXBD down-regulated the expression of chemerin in peripheral blood and up-regulated the expression of cyclic adenosine monophosphate(cAMP) and protein kinase A(PKA) in the liver. After treatment with GXBD, the protein levels of chemerin and CMKLR1 in the liver, abdominal fat, and heart were down-regulated, while the protein levels of PPARα in the liver and abdominal fat were up-regulated. In conclusion, GXBD significantly ameliorated the disorders of glycolipid metabolism in the T2DM-AMI model by regulating the chemerin/CMKLR1/PPARα signaling pathway to exert a protective effect on the damaged myocardium. This study provides a theoretical basis for further clinical study of GXBD against T2DM-AMI and is a manifestation of TCM treatment of phlegm and turbidity causing obstruction at the protein level.

Screening of Platycodonis Radix Fractions for Antiobesity Activities and Elucidation of Its Molecular Mechanisms in High-Fat Diet-Fed C57BL/6 Mice.

Obesity is a threat to public health and effective new medications are required. Platycodonis Radix (PR) is a traditional medicinal/dietary plant with activities against obesity. Using mice given a diet rich in fat, the antiobesity components of PR were identified and their molecular mechanisms were clarified further in this investigation. Initially, the impacts of PR fractions on liver histology and biochemical markers were assessed. Subsequently, the degrees of lipogenic and lipolytic gene and protein expressions were determined. Oral administration of PR polysaccharides (PG) (0.80 g/kg body weight) improved liver function (alanine aminotransferase and aspartate aminotransferase) and its antioxidant activities (total superoxide dismutase, glutathione peroxidase, and malondialdehyde), as well as alleviated blood lipid (total cholesterol, total triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol) values, inflammatory systemic (TNF-α and IL-1ß), and histological abnormalities within the liver. Furthermore, PG administration downregulated the expression for lipogenic genes (ACC and FAS) and upregulated the expression for the lipolytic gene (PPARα, LPL, CPT1, and HSL). Importantly, PG raised AMPK phosphorylation and decreased SREBP-1c protein synthesis. Thus, it is possible that PG stimulates the AMPK-LPL/HSL path (lipolytic route) plus the AMPK-ACC/PPARα-CPT1 path (associated to ß-oxidation of fatty acids), while inhibiting the AMPK/(SREBP-1c)-ACC/FAS path (lipogenic route). In summary, PG has the ability to regulate lipid metabolism, and it may be useful to pharmacologically activate AMPK with PG to prevent and cure obesity.

Comprehensive analysis of peroxisome proliferator-activated receptors to predict the drug resistance, immune microenvironment, and prognosis in stomach adenocarcinomas.

Background: Peroxisome proliferator-activated receptors (PPARs) exert multiple functions in the initiation and progression of stomach adenocarcinomas (STAD). This study analyzed the relationship between PPARs and the immune status, molecular mutations, and drug therapy in STAD. Methods: The expression profiles of three PPAR genes (PPARA, PPARD and PPARG) were downloaded from The Cancer Genome Atlas (TCGA) dataset to analyze their expression patterns across pan-cancer. The associations between PPARs and clinicopathologic features, prognosis, tumor microenvironment, genome mutation and drug sensitivity were also explored. Co-expression between two PPAR genes was calculated using Pearson analysis. Regulatory pathways of PPARs were scored using gene set variation analysis (GSVA) package. Quantitative real-time polymerase chain reaction (qRT-PCR), Western blot, Cell Counting Kit-8 (CCK-8) assay and transwell assay were conducted to analyze the expression and function of the PPAR genes in STAD cell lines (AGS and SGC7901 cells). Results: PPARA, PPARD and PPARG were more abnormally expressed in STAD samples and cell lines when compared to most of 32 type cancers in TCGA. In STAD, the expression of PPARD was higher in Grade 3+4 and male patients, while that of PPARG was higher in patient with Grade 3+4 and age > 60. Patients in high-PPARA expression group tended to have longer survival time. Co-expression analysis revealed 6 genes significantly correlated with the three PPAR genes in STAD. Single-sample GSEA (ssGSEA) showed that the three PPAR genes were enriched in 23 pathways, including MITOTIC_SPINDLE, MYC_TARGETS_V1, E2F_TARGETS and were closely correlated with immune cells, including NK_cells_resting, T_cells_CD4_memory_resting, and macrophages_M0. Immune checkpoint genes (CD274, SIGLEC15) were abnormally expressed between high-PPAR expression and low-PPAR expression groups. TTN, MUC16, FAT2 and ANK3 genes had a high mutation frequency in both high-PPARA/PPARG and low-PPARA/PPARG expression group. Fourteen and two PPARA/PPARD drugs were identified to be able to effectively treat patients in high-PPARA/PPARG and low-PPARA/PPARG expression groups, respectively. We also found that the chemotherapy drug Vinorelbine was positively correlated with the three PPAR genes, showing the potential of Vinorelbine to serve as a treatment drug for STAD. Furthermore, cell experiments demonstrated that PPARG had higher expression in AGS and SGC7901 cells, and that inhibiting PPARG suppressed the viability, migration and invasion of AGS and SGC7901 cells. Conclusions: The current results confirmed that the three PPAR genes (PPARA, PPARD and PPARG) affected STAD development through mediating immune microenvironment and genome mutation.

Assessment of the mode of action of perchloroethylene-induced mouse liver tumors.

Perchloroethylene (PCE) is used as a solvent and chemical intermediate. Following chronic inhalation exposure, PCE selectively induced liver tumors in mice. Understanding the mode of action (MOA) for PCE carcinogenesis in mice is important in defining its possible human cancer risk. The proposed MOA is based on the extensive examination of the peer-reviewed studies that have assessed the mouse liver effects of PCE and its major oxidative metabolite trichloroacetic acid (TCA). Similar to PCE, TCA has also been demonstrated to liver tumors selectively in mice following chronic exposure. The Key Events (KE) of the proposed PCE MOA involve oxidative metabolism of PCE to TCA [KE 1]; activation of the peroxisome proliferator-activated receptor alpha (PPARα) [KE 2]; alteration in hepatic gene expression including cell growth pathways [KE 3]; increase in cell proliferation [KE 4]; selective clonal expansion of hepatic preneoplastic foci [KE 5]; and formation of hepatic neoplasms [KE 6]. The scientific evidence supporting the PPARα MOA for PCE is strong and satisfies the requirements for a MOA analysis. The PPARα liver tumor MOA in rodents has been demonstrated not to occur in humans; thus, human liver cancer risk to PCE is not likely.