Liver cancer is the fourth leading cause of cancer-related deaths with a steadily increasing rate worldwide, as a well-known hallmark of liver cancer, metabolic alterations are related to liposomal changes, a common characteristic of primary liver cancers based on recent lipidomics studies. Peroxisome proliferator-activated receptor α (PPARα) is a ligand-activated transcription factor with important lipid homeostasis function, therefore we aimed to understand the molecular mechanisms and pathways that activate PPARα after using PPAR-α agonist WY-14643 and identify candidate biomarkers related to PPARα activity and evaluate their effects in liver cancer. The data from differently expressed genes (DEGs) between liver cancer tissue from obese subjects alone and liver tissue after treatment were evaluated by DESeq2 and module genes were analyzed using weighted gene co-expression network analysis (WGCNA). Final candidate genes were identified by intersecting genes among highly ranked DEGs and the brown module, which demonstrated a significant negative correlation with drug treatments. We conducted a protein-protein interaction network, and KEGG enrichment analysis, and core hub genes (CD40, CXCL9, CXCL10, TNFSF14, GBP2, GBP3, APOL3, CLDN1) were identified using the cyto-hubba plugin, among them we focused on GBP2 that plays key roles in oncogenesis and evaluate its expressional with clinical outcomes. In conclusion, the WGCNA-based co-expression network identified GBP2 as one of the hub genes with a negative relation with PPARα agonist treatments. higher expression of GBP2 was closely associated with HCC progression. Therefore, GBP2 might be a potential candidate for the study of PPARα activity in HCC.

While fatty acid oxidation (FAO) in mitochondria is a primary energy source for quiescent lymphocytes, the impact of promoting FAO in activated lymphocytes undergoing metabolic reprogramming remains unclear. Here, we demonstrate that pemafibrate, a selective PPARα modulator used clinically for the treatment of hypertriglyceridemia, transforms metabolic system of T-cells and alleviates several autoimmune diseases. Pemafibrate suppresses Th17 cells but not Th1 cells, through the inhibition of glutaminolysis and glycolysis initiated by enhanced FAO. In contrast, a conventional PPARα agonist fenofibrate significantly inhibits cell growth by restraining overall metabolisms even at a dose insufficient to induce fatty acid oxidation. Clinically, patients receiving pemafibrate showed a significant decrease of Th17/Treg ratio in peripheral blood. Our results suggest that augmented FAO by pemafibrate-mediated selective activation of PPARα restrains metabolic programs of Th17 cells and could be a viable option for the treatment of autoimmune diseases.

Males are at higher risk for developing metabolic dysfunction-associated steatohepatitis (MASH) than females; however, mechanisms mediating sexual dimorphism in MASH development are not completely understood. Nutrition-based mouse models suggest that dysregulated fatty acid biosynthesis promotes MASH. Drugs recapitulate MASH without diet variabilities. This brief report investigates associations of sexual dimorphism with male susceptibility to MASH utilizing a drug-induced MASH model and focuses on very-long-chain fatty acid biosynthesis pathways. We assessed male and female mouse livers at 5 and 15 weeks following MASH induction by immunizations and age-matched un-immunized controls utilizing Western blot. Our results suggest that PPAR alpha and CYP4a12a protect females, while CYP4v2 does not protect males from MASH development. Our results have important implications for understanding sexual dimorphism in the pathogenesis of MASH.

BACKGROUND: Primary human hepatocytes (PHHs) are highly valuable for drug-metabolism evaluation, liver disease modeling and hepatocyte transplantation. However, their availability is significantly restricted due to limited donor sources, alongside their constrained proliferation capabilities and reduced functionality when cultured in vitro. To address this challenge, we aimed to develop a novel method to efficiently expand PHHs in vitro without a loss of function.
METHODS: By mimicking the in vivo liver regeneration route, we developed a two-step strategy involving the de-differentiation/expansion and subsequent maturation of PHHs to generate abundant functional hepatocytes in vitro. Initially, we applied SiPer, a prediction algorithm, to identify candidate small molecules capable of activating liver regenerative transcription factors, thereby formulating a novel hepatic expansion medium to de-differentiate PHHs into proliferative human hepatic progenitor-like cells (ProHPLCs). These ProHPLCs were then re-differentiated into functionally mature hepatocytes using a new hepatocyte maturation condition. Additionally, we investigated the underlying mechanism of PHHs expansion under our new conditions.
RESULTS: The novel hepatic expansion medium containing hydrocortisone facilitated the de-differentiation of PHHs into ProHPLCs, which exhibited key hepatic progenitor characteristics and demonstrated a marked increase in proliferation capacity compared to cells cultivated in previously established expansion conditions. Remarkably, these subsequent matured hepatocytes rivaled PHHs in terms of transcriptome profiles, drug metabolizing activities and in vivo engraftment capabilities. Importantly, our findings suggest that the enhanced expansion of PHHs by hydrocortisone may be mediated through the PPARα signaling pathway and regenerative transcription factors.
CONCLUSIONS: This study presents a two-step strategy that initially induces PHHs into a proliferative state (ProHPLCs) to ensure sufficient cell quantity, followed by the maturation of ProHPLCs into fully functional hepatocytes to guarantee optimal cell quality. This approach offers a promising means of producing large numbers of seeding cells for hepatocyte-based applications.

Atherosclerosis is the pathological cause of atherosclerotic cardiovascular disease (ASCVD), which rapidly progresses during the cellular senescence. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) reduce major cardiovascular events in patients with ASCVD and have potential antisenescence effects. Here, we investigate the effects of the SGLT2 inhibitor dapagliflozin on cellular senescence in atherosclerotic mice. Compared with ApoE-/- control mice treated with normal saline, those in the ApoE-/- dapagliflozin group, receiving intragastric dapagliflozin (0.1 mg kg-1 d-1) for 14 weeks, exhibited the reduction in the total aortic plaque area (48.8%±6.6% vs. 74.6%±8.0%, P<0.05), the decrease in the lipid core area ((0.019±0.0037) mm2vs. (0.032±0.0062) mm2, P<0.05) and in the percentage of senescent cells within the plaques (16.4%±3.7% vs. 30.7%±2.0%, P<0.01), while the increase in the thickness of the fibrous cap ((21.6±2.1) µm vs. (14.6±1.5) µm, P<0.01). Transcriptome sequencing of the aortic arch in the mice revealed the involvement of the PPARα and the fatty acid metabolic signaling pathways in dapagliflozin\'s mechanism of ameliorating cellular aging and plaque progression. In vitro, dapagliflozin inhibited the expression of PPARα and its downstream signal FABP4, by which the accumulation of senescent cells in human aortic smooth muscle cells (HASMCs) was reduced under high-fat conditions. This effect was accompanied by a reduction in the intracellular lipid content and alleviation of oxidative stress. However, these beneficial effects of dapagliflozin could be reversed by the PPARα overexpression. Bioinformatics analysis and molecular docking simulations revealed that dapagliflozin might exert its effects by directly interacting with the RXRA protein, thereby influencing the expression of the PPARα signaling pathway. In conclusion, the cellular senescence of aortic smooth muscle cells is potentially altered by dapagliflozin through the suppression of the RXRA-PPARα-FABP4 signaling pathway, resulting in a deceleration of atherosclerotic progression.

OBJECTIVE: Metabolic-associated fatty liver disease (MAFLD) represents one of the most prevalent chronic liver conditions worldwide, but its precise pathogenesis remains unclear. This research endeavors to elucidate the involvement and molecular mechanisms of polyribonucleotide nucleotidyltransferase 1 (PNPT1) in the progression of MAFLD.
METHODS: The study employed western blot and qRT-PCR to evaluate PNPT1 levels in liver specimens from individuals diagnosed with MAFLD and in mouse models subjected to a high-fat diet. Cellular studies investigated the effects of PNPT1 on lipid metabolism, apoptosis, and mitochondrial stability in hepatocytes. Immunofluorescence was utilized to track the subcellular movement of PNPT1 under high lipid conditions. RNA immunoprecipitation and functional assays were conducted to identify interactions between PNPT1 and Mcl-1 mRNA. The role of PPARα as an upstream transcriptional regulator of PNPT1 was investigated. Recombinant adenoviral vectors were utilized to modulate PNPT1 expression in vivo.
RESULTS: PNPT1 was found to be markedly reduced in liver tissues from MAFLD patients and HFD mice. In vitro, PNPT1 directly regulated hepatic lipid metabolism, apoptosis, and mitochondrial stability. Under conditions of elevated lipids, PNPT1 relocated from mitochondria to cytoplasm, modifying its physiological functions. RNA immunoprecipitation revealed that the KH and S1 domains of PNPT1 bind to and degrade Mcl-1 mRNA, which in turn affects mitochondrial permeability. The transcriptional regulator PPARα was identified as a significant influencer of PNPT1, impacting both its expression and subsequent cellular functions. Alterations in PNPT1 expression were directly correlated with the progression of MAFLD in mice.
CONCLUSIONS: The study confirms the pivotal function of PNPT1 in the development of MAFLD through its interactions with Mcl-1 and its regulatory effects on lipid metabolism and mitochondrial stability. These insights highlight the intricate association between PNPT1 and MAFLD, shedding light on its molecular pathways and presenting a potential new therapeutic avenue for MAFLD management.

Energy metabolism disorder, mainly exhibiting the inhibition of fatty acid degradation and lipid accumulation, is highly related with aging acceleration. However, the intervention measures are deficient. Here, we reported Omega-3 polyunsaturated fatty acids (Omega-3 PUFAs), especially EPA, exerted beneficial effects on maintaining energy metabolism and lipid homeostasis to slow organ aging. As the endogenous agonist of peroxisome proliferator-activated receptor α (PPARα), Omega-3 PUFAs significantly boosted fatty acid β-oxidation and ATP production in multiple aged organs. Consequently, Omega-3 PUFAs effectively inhibited age-related pathological changes, preserved organ function, and retarded aging process. The beneficial effects of Omega-3 PUFAs were also testified in mfat-1 transgenic mice, which spontaneously generate abundant endogenous Omega-3 PUFAs. In conclusion, our study innovatively demonstrated Omega-3 PUFAs administration in diet slow aging through promoting energy metabolism. The supplement of Omega-3 PUFAs or fat-1 transgene provides a promising therapeutic approach to promote healthy aging in the elderly.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the leading cause of liver-related morbidity and mortality, with hepatic steatosis being the hallmark symptom. Salvia miltiorrhiza Bunge (Smil, Dan-Shen) and Ligusticum striatum DC (Lstr, Chuan-Xiong) are commonly used to treat cardiovascular diseases and have the potential to regulate lipid metabolism. However, whether Smil/Lstr combo can be used to treat NAFLD and the mechanisms underlying its lipid-regulating properties remain unclear.
OBJECTIVE: To assess the feasibility and reliability of a short-term high-fat diet (HFD) induced zebrafish model for evaluating hepatic steatosis phenotype and to investigate the liver lipid-lowering effects of Smil/Lstr, as well as its active components.
METHODS: The phenotypic alterations of liver and multiple other organ systems were examined in the HFD zebrafish model using fluorescence imaging and histochemistry. The liver-specific lipid-lowering effects of Smil/Lstr combo were evaluated endogenously. The active molecules and functional mechanisms were further explored in zebrafish, human hepatocytes, and hamster models.
RESULTS: In 5-day HFD zebrafish, significant lipid accumulation was detected in the blood vessels and the liver, as evidenced by increased staining with Oil Red O and fluorescent lipid probes. Hepatic hypertrophy was observed in the model, along with macrovesicular steatosis. Smil/Lstr combo administration effectively restored the lipid profile and alleviated hepatic hypertrophy in the HFD zebrafish. In oleic-acid stimulated hepatocytes, Smil/Lstr combo markedly reduced lipid accumulation and cell damage. Subsequently, based on zebrafish phenotypic screening, the natural phthalide senkyunolide I (SEI) was identified as a major molecule mediating the lipid-lowering activities of Smil/Lstr combo in the liver. Moreover, SEI upregulated the expression of the lipid metabolism regulator PPARα and downregulated fatty acid translocase CD36, while a PPARα antagonist sufficiently blocked the regulatory effect of SEI on hepatic steatosis. Finally, the roles of SEI on hepatic lipid accumulation and PPARα signaling were further verified in the hamster model.
CONCLUSIONS: We proposed a zebrafish-based screening strategy for modulators of hepatic steatosis and discovered the regulatory roles of Smil/Lstr combo and its component SEI on liver lipid accumulation and PPARα signaling, suggesting their potential value as novel candidates for NAFLD treatment.

The Yak (Bos grunniens) is a special breed of livestock predominantly distributed in the Qinghai-Tibet Plateau of China. Intramuscular fat (IMF) content in beef cattle is a vital indicator of meat quality. In this study, RNA-Seq and Protein-Seq were respectively employed to sequence the transcriptome and proteome of the longissimus dorsi (LD) tissue from 4-year-old yaks with significant differences in IMF content under the same fattening conditions. Five overlapping genes (MYL3, ACADS, L2HGDH, IGFN1, and ENSBGRG00000000-926) were screened using combined analysis. Functional verification tests demonstrated that the key gene ACADS inhibited yak intramuscular preadipocyte (YIMA) differentiation and proliferation, promoted mitochondrial biogenesis gene expression, and increased the mitochondrial membrane potential (MMP). Furthermore, co-transfection experiments further demonstrated that interfering with ACADS reversed the effect of PPARα agonists in promoting lipid differentiation. In conclusion, ACADS potentially inhibits lipid deposition in YIAMs by regulating the PPARα signalling pathway. These findings offer insights into the molecular mechanisms underlying yak meat quality.

Endoplasmic reticulum (ER) stress is a major cause of hepatic steatosis through increasing de novo lipogenesis. Forkhead box O6 (FoxO6) is a transcription factor mediating insulin signaling to glucose and lipid metabolism. Therefore, dysregulated FoxO6 is involved in hepatic lipogenesis. This study elucidated the role of FoxO6 in ER stress-induced hepatic steatosis in vivo and in vitro. Hepatic ER stress responses and β-oxidation were monitored in mice overexpressed with constitutively active FoxO6 allele and FoxO6-null mice. For the in vitro study, liver cells overexpressing constitutively active FoxO6 and FoxO6-siRNA were treated with high glucose, and lipid metabolism alterations were measured. ER stress-induced FoxO6 activation suppressed hepatic β-oxidation in vivo. The expression and transcriptional activity of peroxisome proliferator-activated receptor α (PPARα) were significantly decreased in the constitutively active FoxO6 allele. Otherwise, inhibiting β-oxidation genes were reduced in the FoxO6-siRNA and FoxO6-KO mice. Our data showed that the FoxO6-induced hepatic lipid accumulation was negatively regulated by insulin signaling. High glucose treatment as a hyperglycemia condition caused the expression of ER stress-inducible genes, which was deteriorated by FoxO6 activation in liver cells. However, high glucose-mediated ER stress suppressed β-oxidation gene expression through interactions between PPARα and FoxO6 corresponding to findings in the in vivo study-lipid catabolism is also regulated by FoxO6. Furthermore, insulin resistance suppressed b-oxidation through the interaction between FoxO6 and PPARα promotes hepatic steatosis, which, due to hyperglycemia-induced ER stress, impairs insulin signaling. KEY MESSAGES: Our original aims were to delineate the interrelation between the regulation of PPARα and the transcription factor FoxO6 pathway in relation to lipid metabolism at molecular levels. Evidence on high glucose promoted FoxO6 activation induced lipid accumulation in liver cells. The effect of PPARα activation of the insulin signaling. FoxO6 plays a pivotal role in hepatic lipid accumulation through inactivation of PPARα in FoxO6-overexpression mice.