Carnitine Palmitoyltransferase Research Articles

PPARα-mediated lipid metabolism reprogramming supports anti-EGFR therapy resistance in head and neck squamous cell carcinoma

Anti-epidermal growth factor receptor (EGFR) therapy (cetuximab) shows a limited clinical benefit for patients with locally advanced or recurrent/metastatic head and neck squamous cell carcinoma (HNSCC), due to the frequent occurrence of secondary resistance mechanisms. Here we report that cetuximab-resistant HNSCC cells display a peroxisome proliferator-activated receptor alpha (PPARα)-mediated lipid metabolism reprogramming, with increased fatty acid uptake and oxidation capacities, while glycolysis is not modified. This metabolic shift makes cetuximab-resistant HNSCC cells particularly sensitive to a pharmacological inhibition of either carnitine palmitoyltransferase 1A (CPT1A) or PPARα in 3D spheroids and tumor xenografts in mice. Importantly, the PPARα-related gene signature, in human clinical datasets, correlates with lower response to anti-EGFR therapy and poor survival in HNSCC patients, thereby validating its clinical relevance. This study points out lipid metabolism rewiring as a non-genetic resistance-causing mechanism in HNSCC that may be therapeutically targeted to overcome acquired resistance to anti-EGFR therapy.

ANGPTL3 overcomes sorafenib resistance via suppression of SNAI1 and CPT1A in liver cancer.

Liver cancer, encompassing hepatocellular carcinoma (HCC) and hepatoblastoma, the latter of which primarily occurs in early childhood, is the most common malignant tumor arising from liver and is responsible for a significant number of cancer-related deaths worldwide. Targeted drugs have been used for anti-liver cancer treatment in the advanced stage, while their efficacy is greatly compromised by development of drug resistance. Drug resistance is a complicated process regulated by intrinsic and extrinsic signals and has been associated with poorer prognosis in cancer patients. In the current study, online available dataset analysis uncovered that angiopoietin-like protein 3 (ANGPTL3) manifested lower expression in sorafenib-resistant liver cancer cell lines. Additionally, ANGPTL3 was downregulated in HCC tissues, with its expression positively correlated with good prognosis. Functionally, ectopic expression of ANGPTL3 re-sensitized sorafenib-resistant cells, enhancing the sorafenib-induced reduction in cell viability and migration by suppressing zinc finger protein SNAI1 (SNAI1) expression and the protein stability of carnitine O-palmitoyltransferase 1, liver isoform (CPT1A). Clinical correlation analysis revealed that ANGPTL3 was negatively associated with SNAI1 expression. In conclusion, we identify a novel association between ANGPTL3, SNAI1 and CPT1A on sorafenib therapeutic response. Targeting ANGPTL3/SNAI1/CPT1A axis may serve as a therapeutic approach to improve prognosis of liver cancer patients with sorafenib resistance.

Autophagic flux-lipid droplet biogenesis cascade sustains mitochondrial fitness in colorectal cancer cells adapted to acidosis

Cancer development is associated with adaptation to various stressful conditions, such as extracellular acidosis. The adverse tumor microenvironment also selects for increased malignancy. Mitochondria are integral in stress sensing to allow for tumor cells to adapt to stressful conditions. Here, we show that colorectal cancer cells adapted to acidic microenvironment (CRC-AA) are more reliant on oxidative phosphorylation than their parental cells, and the acetyl-CoA in CRC-AA cells are generated from fatty acids and glutamine, but not from glucose. Consistently, CRC-AA cells exhibit increased mitochondrial mass and fitness that depends on an upregulated autophagic flux-lipid droplet axis. Lipid droplets (LDs) function as a buffering system to store the fatty acids derived from autophagy and to protect mitochondria from lipotoxicity in CRC-AA cells. Blockade of LD biogenesis causes mitochondrial dysfunction that can be rescued by inhibiting carnitine palmitoyltransferase 1 α (CPT1α). High level of mitochondrial superoxide is essential for the AMPK activation, resistance to apoptosis, high autophagic flux and mitochondrial function in CRC-AA cells. Thus, our results demonstrate that the cascade of autophagic flux and LD formation plays an essential role in sustaining mitochondrial fitness to promote cancer cell survival under chronic acidosis. Our findings provide insight into the pro-survival metabolic plasticity in cancer cells under microenvironmental or therapeutic stress and imply that this pro-survival cascade may potentially be targeted in cancer therapy.

The Ethanol Extract of Sugemule-3 Decoction Treats Isoproterenol-induced Heart Failure in Rats via PPARγ/PGC-1 Pathway

Background The herbs Baidoukou (the fruit of Amomum compactum Sol. ex Maton), Baijusheng (the fruit of Lactuca sativa L.), and Biba ( Piper longum L.) make up the traditional Mongolian medicine known as Sugemule-3 decoction. Purpose: Heart failure (HF) is severely impacted; however, the pharmacological mechanism behind it is yet unclear. This investigation looked at the Sugemule-3 ethanol extract’s therapeutic mechanism for isoproterenol-induced HF in rats. Methods To create a HF model, isoproterenol was administered to Wistar rats. Following the model’s successful establishment, various medications were administered for 4 weeks. The electrical signals of cardiac fluctuations, cardiac morphology, and function were observed using electrocardiogram (ECG) and echocardiography. The rats were killed 4 weeks later, and the hearts were observed using an electron microscope and HE staining. Cardiomyocyte apoptosis was observed using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. The levels of markers in serum were determined using enzyme-linked immunosorbent assay (ELISA). Western blot and immunohistochemistry were used to detect the expression of proteins in rats. Results Our findings show that isoproterenol injection subcutaneously interfered with the structure and function of the left ventricle, particularly during systole. In the model group, the level of oxidative stress index malondialdehyde ( p < 0.01) increased with the decrease in anti-oxidant enzymes such as superoxide dismutase ( p < 0.01) and glutathione peroxidase ( p < 0.01). Sugemule-3 ethanol extract considerably reduced the harmful effects of isoproterenol on the rat myocardium. Additionally, isoproterenol increased the level of peroxisome proliferator-activated receptor (PPAR), carnitine palmitoyl transferase-1 (CPT-1), phosphoenolpyruvate carboxylase (PEPCK), stearyl CoA desaturase-1 (SCD-1), and ubiquitin-conjugating (UCB) expression while decreasing the level of peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1) expression, leading to cardiometabolic diseases. Sugemule-3 ethanol extract improved cardiac metabolism. Conclusion The findings demonstrate that Sugemule-3 ethanol extract may improve energy metabolism of cardiomyocytes and alleviate isoproterenol-induced HF through inhibiting the peroxisome proliferator-activated receptor gamma (PPARγ)/PGC-1 signaling pathway.

Longitudinal association between DNA methylation and type 2 diabetes: findings from the KORA F4/FF4 study

BackgroundType 2 diabetes (T2D) has been linked to changes in DNA methylation levels, which can, in turn, alter transcriptional activity. However, most studies for epigenome-wide associations between T2D and DNA methylation comes from cross-sectional design. Few large-scale investigations have explored these associations longitudinally over multiple time-points.MethodsIn this longitudinal study, we examined data from the Cooperative Health Research in the Region of Augsburg (KORA) F4 and FF4 studies, conducted approximately seven years apart. Leucocyte DNA methylation was assessed using the Illumina EPIC and 450K arrays. Linear mixed-effects models were employed to identify significant associations between methylation sites and diabetes status, as well as with fasting plasma glucose (FPG), hemoglobin A1c (HbA1c), homoeostasis model assessment of beta cell function (HOMA-B), and homoeostasis model assessment of insulin resistance (HOMA-IR). Interaction effects between diabetes status and follow-up time were also examined. Additionally, we explored CpG sites associated with persistent prediabetes or T2D, as well as the progression from normal glucose tolerance (NGT) to prediabetes or T2D. Finally, we assessed the associations between the identified CpG sites and their corresponding gene expression levels.ResultsA total of 3,501 observations from 2,556 participants, with methylation measured at least once across two visits, were included in the analyses. We identified 64 sites associated with T2D including 15 novel sites as well as known associations like those with the thioredoxin-interacting protein (TXNIP) and ATP-binding cassette sub-family G member 1 (ABCG1) genes. Of these, eight CpG sites exhibited different rates of annual methylation change between the NGT and T2D groups, and seven CpG sites were linked to the progression from NGT to prediabetes or T2D, including those annotated to mannosidase alpha class 2a member 2 (MAN2A2) and carnitine palmitoyl transferase 1 A (CPT1A). Longitudinal analysis revealed significant associations between methylation and FPG at 128 sites, HbA1c at 41 sites, and HOMA-IR at 57 sites. Additionally, we identified 104 CpG-transcript pairs in whole blood, comprising 40 unique CpG sites and 96 unique gene transcripts.ConclusionsOur study identified novel differentially methylated loci linked to T2D as well as to changes in diabetes status through a longitudinal approach. We report CpG sites with different rates of annual methylation change and demonstrate that DNA methylation associated with T2D is linked to following transcriptional differences. These findings provide new insights into the molecular mechanisms of diabetes development.Graphical abstract

Alcohol promotes CPT1A-induced lipid metabolism disorder to sentinel-regulate acute pancreatitis

Background and aimsPrevious studies have confirmed that alcohol can increase the sensitivity of the pancreas to stressors and exacerbate the severity of pancreatitis when excessive alcohol intake is combined with other causes. In the current work, this study attempted to explore how does alcohol regulate cerulein-induced acute pancreatitis, especially before inflammation occurs.MethodsProteomics was performed to analyze the differentially expressed proteins in pancreatic tissues from a rat model of pancreatitis. The metabolite levels in the pancreatic tissue, serum of rats and serum of persons with a history of alcohol consumption were detected by LC‒MS/MS. In the present study the impact of etomoxir (a carnitine palmitoyl-transferase 1A-specific inhibitor) treatment on AR42J cells treated with alcohol and the effect of etomoxir injection on the inflammatory response in an alcohol + cerulein-induced AAP rat model was evaluated.ResultsWhen treated with the same amount of cerulein, the rats that ingested alcohol presented with more severe pancreatitis. The proteomics results revealed that the fatty acid degradation pathway was closely related to the development of alcoholic acute pancreatitis, and CPT1A exhibited the greatest increase (approximately twofold increase). The products (acylcarnitines) of CPT1A were changed in the serum of persons with a history of alcohol consumption. Etomoxir treatment mitigates the influence of alcohol stimulation on the aberrant expression of proteins associated with oxidative stress, increased ROS production, mitochondrial ultrastructural alterations and mitochondrial dysfunction in AR42J cells. Etomoxir injection reduced the inflammatory response in the AAP rat model.ConclusionAlcohol upregulates CPT1A protein expression in pancreatic tissue, resulting in abnormal lipid metabolism. The products of lipid metabolism, ROS, contribute to mitochondrial ultrastructural alterations and mitochondrial dysfunction. These changes act as sentinel events that regulate acute pancreatitis.

GNA15 induces drug resistance in B cell acute lymphoblastic leukemia by promoting fatty acid oxidation via activation of the AMPK pathway.

The prognosis of B cell acute lymphoblastic leukemia (B-ALL) is poor, primarily due to drug resistance and relapse. Ga15, encoded by GNA15, belongs to the G protein family, with G protein-coupled receptors playing a crucial role in multiple biological process. GNA15 has been reported to be involved in various malignancies; however, its potential role in B-ALL remain unknown. In this study, high expression of GNA15 in B-ALL was observed in multiple databases. We further confirmed an increased transcriptional level of GNA15 in newly diagnosed B-ALL patients which was closely correlated with relapse. We showed that GNA15 promoted cell growth, inhibited apoptosis and enhanced drug resistance in leukemia cell lines. Metabolomics analysis revealed a significant enrichment of fatty acid oxidation (FAO) according to the GNA15 expression. We further confirmed that GNA15 could enhance FAO process as evidenced by the upregulation of key molecules involved in FAO including carnitine palmitoyl transferase1 (CPT1), CPT2 and CD36. And inhibition of FAO using etomoxir partially reversed the drug resistance caused by high expression of GNA15. Mechanism study showed that GNA15 promoted FAO by up-regulation of AMPK phosphorylation thus leading to survival advantage in leukemia cells. In conclusion, we observed elevated GNA15 transcript levels in B-ALL, which were associated with relapse. GNA15 could induce drug resistance though activation of the AMPK/FAO axis in leukemia cell lines. Targeting GNA15 and FAO may represent potential therapeutic strategy for improving the prognosis of B-ALL.

Endothelial Cpt1a Inhibits Neonatal Hyperoxia-Induced Pulmonary Vascular Remodeling by Repressing Endothelial-Mesenchymal Transition.

Pulmonary hypertension (PH) increases the mortality of preterm infants with bronchopulmonary dysplasia (BPD). There are no curative therapies for this disease. Lung endothelial carnitine palmitoyltransferase 1a (Cpt1a), the rate-limiting enzyme of the carnitine shuttle system, is reduced in a rodent model of BPD. It is unknown whether endothelial Cpt1a reduction causes pulmonary vascular (PV) remodeling. The latter can be the result of endothelial-mesenchymal transition (EndoMT). Here, endothelial cell (EC)-specific Cpt1a KO and WT mice (<12h old) are exposed to hyperoxia (70% O2) for 14 days and allow them to recover in normoxia until postnatal day 28. Hyperoxia causes PH, which is aggravated in EC-specific Cpt1a KO mice. Upregulating endothelial Cpt1a expression inhibits hyperoxia-induced PV remodeling. Hyperoxia causes lung EndoMT, detected by immunofluorescence, scRNA-sequencing, and EC lineage tracing, which is further increased in EC-specific Cpt1a KO mice. Blocking EndoMT inhibits hyperoxia-induced PV remodeling. Male mice under the same high oxygen conditions develop a higher degree of PH than females, which is associated with reduced endothelial Cpt1a expression. Conclusively, neonatal hyperoxia causes PH by decreasing endothelial Cpt1a expression and upregulating EndoMT. This provides a valuable strategy for developing targeted therapies by upregulating endothelial Cpt1a levels or inhibiting EndoMT to treat BPD-associated PH.

Loss of Cpt1a results in elevated glucose-fueled mitochondrial oxidative phosphorylation and defective hematopoietic stem cells.

Hematopoietic stem cells (HSCs) rely on self-renewal to sustain stem cell potential and undergo differentiation to generate mature blood cells. Mitochondrial fatty acid β-oxidation (FAO) is essential for HSC maintenance. However, the role of Carnitine palmitoyl transferase 1a (CPT1A), a key enzyme in FAO, remains unclear in HSCs. Using a Cpt1a hematopoietic specific conditional knock-out (Cpt1aΔ/Δ) mouse model, we found that loss of Cpt1a leads to HSC defects, including loss of HSC quiescence and self-renewal, and increased differentiation. Mechanistically, we find that loss of Cpt1a results in elevated levels of mitochondrial respiratory chain complex components and their activities, as well as increased ATP production, and accumulation of mitochondrial reactive oxygen species (mitoROS) in HSCs. Taken together, this suggests hyperactivation of mitochondria and metabolic rewiring via upregulated glucose-fueled oxidative phosphorylation (OXPHOS). In summary, our findings demonstrate a novel role for Cpt1a in HSC maintenance and provide insight into the regulation of mitochondrial metabolism via control of the balance between FAO and glucose-fueled OXPHOS.

Bisphenol S Induces Lipid Metabolism Disorders in HepG2 and SK-Hep-1 Cells via Oxidative Stress.

Bisphenol S (BPS) is a typical endocrine disruptor associated with obesity. To observe BPS effects on lipid metabolism in HepG2 and SK-Hep-1 human HCC cells, a CCK-8 assay was used to assess cell proliferation in response to BPS, and the optimal concentration of BPS was selected. Biochemical indices such as triglyceride (TG) and total cholesterol (T-CHO), and oxidative stress indices such as malondialdehyde (MDA) and catalase (CAT) were measured. ROS and MDA levels were significantly increased after BPS treatment for 24 h and 48 h (p < 0.05), indicating an oxidative stress response. Alanine aminotransferase (ALT), T-CHO, and low-density lipoprotein cholesterol (LDL-C) levels also increased significantly after 24 or 48 h BPS treatments (p < 0.05). RT-PCR and Western blot analyses detected mRNA or protein expression levels of peroxisome proliferator-activated receptor α (PPARα) and sterol regulatory element-binding protein 1c (SREBP1C). The results indicated that BPS could inhibit the mRNA expression of PPARα and carnitine palmitoyl transferase 1B (CPT1B), reduce lipid metabolism, promote mRNA or protein expression of SREBP1C and fatty acid synthase (FASN), and increase lipid synthesis. Increased lipid droplets were observed using morphological Oil Red O staining. Our study demonstrates that BPS may cause lipid accumulation by increasing oxidative stress and perturbing cellular lipid metabolism.

CPT1 deficiency blocks autophagic flux to promote lipid accumulation induced by co-exposure to polystyrene microplastic and cadmium.

Cadmium (Cd) and polystyrene microplastics (PS-MPs), two ubiquitous environmental contaminants, produce unique synergistic toxicity when co-existing. Key unanswered questions include specific effects on liver function and potential mechanisms. In this study, C57BL/6 mice and AML12 cells were used to establish in vivo and in vitro models to elucidate the effects of combined exposure to PS-MPs and Cd on the liver and their mechanisms. The results showed that the combined effects of PS-MPs and Cd caused significantly more liver damage than exposure alone. As observed by transmission electron microscopy (TEM), the number of autophagosomes was significantly increased in the PS-MPs and Cd co-treated group. In addition, autophagic flux was assayed by RFP-GFP-LC3, a reporter system expressing dual fluorescent proteins, which showed an overwhelming enhancement of autophagic flux damage by co-exposure to PS-MPs and Cd compared to exposure alone. To further investigate the involvement of carnitine palmitoyltransferase1(CPT1) in liver injury induced by co-exposure to Cd and PS-MPs, we co-exposed Baicalin, an activator of CPT1, with PS-MPs and Cd, and showed that activation of CPT1 alleviated the impairment of autophagic fluxes induced by co-exposure of Cd and PS-MPs and further alleviated the changes in lipid accumulation and associated protein levels. In conclusion, the concurrent exposure of PS-MPs and Cd resulted in the blockage of hepatic lipid accumulation and autophagic pathway and further aggravated the toxic damage to the liver. Activation of CPT1 could alleviate the PS-MPs and Cd-induced lipid accumulation and autophagy pathway blockage thus reducing liver injury.

Abnormalities in mitochondrial energy metabolism induced by cryopreservation negatively affect goat sperm motility.

The motility of sperm decreases following cryopreservation, which is closely associated with mitochondrial function. However, the alterations in mitochondrial metabolism after sperm freezing in goats remain unclear. This experiment aimed to investigate the impact of ultra-low temperature freezing on goat sperm's mitochondrial energy metabolism and its potential correlation with sperm motility. The results revealed that goat sperm exhibited mitochondrial vacuolization, reduced matrix density, and significantly decreased levels of high-membrane potential mitochondria and adenosine triphosphate content, accompanied by a substantial increase in reactive oxygen species levels, ultimately leading to a significant decline in sperm viability. Further investigations unveiled that energy-related differential metabolites (capric acid, creatine, and D-glucosamine-6-phosphate) and differential metabolites with antioxidant effects (saikosaponin A, probucol, and cholesterol sulfate) were significantly downregulated. In addition, the activity of key rate-limiting enzymes involved in very long-chain fatty acid biosynthesis and β-oxidation-specifically acetyl-CoA carboxylase, fatty acid synthase, and carnitine palmitoyltransferase I related to capric acid metabolism-was considerably reduced. Furthermore, supplementation of differential metabolite capric acid (500 μM) significantly enhanced the motility of frozen-thawed goat sperm. These findings indicated that the mitochondrial ultrastructure of goat sperm is damaged and energy metabolism becomes abnormal after cryopreservation, potentially affecting sperm viability. The addition of different metabolites such as capric acid to the freezing extender can alleviate the decrease in sperm motility induced by cryopreservation.

Mitochondrial SIRT2-mediated CPT2 deacetylation prevents diabetic cardiomyopathy by impeding cardiac fatty acid oxidation.

Dysregulated energy metabolism, particularly lipid metabolism disorders, has been identified as a key factor in the development of diabetic cardiomyopathy (DCM). Sirtuin 2 (SIRT2) is a deacetylase involved in the regulation of metabolism and cellular energy homeostasis, yet its role in the progression of DCM remains unclear. We observed significantly reduced SIRT2 expression in DCM model mice. Cardiac-specific overexpression of SIRT2 protected mice from streptozotocin/high-fat diet (STZ/HFD)-induced insulin resistance (IR), cell apoptosis, and cardiac dysfunction, whereas its downregulation exacerbated these conditions. Moreover, we found that SIRT2 regulated cardiac lipid accumulation and fatty acid oxidation (FAO), and identified its localization in cardiac mitochondria. Mechanistically, we determined carnitine palmitoyltransferase 2 (CPT2) as a critical substrate of SIRT2, which is implicated in DCM. SIRT2-mediated deacetylation at K239 enhanced CPT2 ubiquitination, resulting in decreased protein stability and subsequent inhibition of FAO and reactive oxygen species (ROS) production. Taken together, these findings suggest that the SIRT2/CPT2 signaling pathway plays a crucial role in DCM progression.

Pachymic acid promotes brown/beige adipocyte differentiation and lipid metabolism in preadipocytes 3T3-L1 MBX.

To investigate the effect of pachymic acid on brown/beige adipocyte differentiation and lipid metabolism in preadipocytes 3T3-L1 MBX. The brown cocktail method was employed to induce 3T3-L1 MBX cells to differentiate into beige adipocytes. The impact of pachymic acid on the viability of 3T3-L1 MBX preadipocytes was evaluated using the CCK-8 assay. The formation of lipid droplets following treatment with pachymic acid was observed through oil red O staining, and the content of lipids in differentiated cells was determined. The expression levels of key browning genes, including uncoupling protein (Ucp) 1, the peroxisome proliferation-activating receptor gamma coactivator (Pgc)-1α, and the transcription factor containing PR domain 16 (Prdm16) were detected by quantitative reverse transcription polymerase chain reaction. The expression of sterol regulatory element binding protein (Srebp) 1c, acetyl-CoA carboxylase (Acc), fatty acid synthetase (Fas), and steroid-sensitive lipase (Hsl), fatty triglyceride hydrolase (Atgl), and carnitine palmitoyl transferase (Cpt) 1 of lipolysis-related genes were also examined. The 3T3-L1 MBX was induced in vitro to form beige adipocytes with high expression of key browning genes, including Ucp1, Pgc-1α, Prdm16, and beige adipose-marker genes, including Cd137, Tbx1, and Tmem26. The concentration range of 0-80 μM pachymic acid was non-cytotoxic to 3T3-L1 MBX. Pachymic acid treatment significantly inhibited the differentiation of 3T3-L1 MBX, resulting in a notable decrease in lipid accumulation content (P<0.01). Additionally, there was a marked increase in the expression of key browning genes and their proteins, such as Ucp1, Pgc-1α, and Prdm16, while the expressions of fat synthesis-related genes Srebp1c, Acc and Fas were significantly decreased (all P<0.05). The expressions of lipolysis-related genes, including Hsl, Atgl, and Cpt1, were significantly increased (all P<0.05). Besides, treating with 20 μmol/L pachymic acid showed the most pronounced effect. Pachymic acid can inhibit fat synthesis and promote lipid decomposition by regulating the brown formation and lipid differentiation of 3T3-L1 MBX preadipocytes.

D-allulose enhances lipid oxidation in HepG2 cells via peroxisome proliferator-activated receptor α (PPARα).

Lipid accumulation in hepatocytes in non-alcoholic steatohepatitis (NASH) is attributed partly to loss of insulin-responsiveness and/or an increased pro-inflammatory state. Since the rare sugar D-allulose has insulin mimetic and anti-inflammatory properties, its effects on lipid accumulation in liver-derived cells was tested. In HepG2 cells exposed to 200 μM oleic acid for 72 h, D-allulose treatment decreased intracellular lipid accumulation with an IC50 = 0.45 ± 0.07 mM. A similar effect was observed in cells treated with 10 μM gemfibrozil. D-allulose and gemfibrozil treatment increased oleic acid β-oxidation. Both D-allulose and gemfibrozil increased peroxisome proliferator-activated receptor α (PPARα) expression (two-fold) relative to control cells, while retinoid X receptor was unchanged. D-allulose and gemfibrozil increased PPARα-dependent genes including those involved in fatty acid β-oxidation (acyl-coenzyme A oxidase 1, long-chain-fatty-acid-coenzyme A ligase 5, and carnitine palmitoyltransferase 1 A). D-allulose and gemfibrozil also increased PPARα reporter gene expression and phosphorylation (Serine 12) which were both inhibited by the mitogen-activated protein (MAP) kinase inhibitor PD098059. Other MAP kinase inhibitors, including SB203580, SP600125, and BIX10289 had no effect on reporter gene expression. Oleic acid treatment, but not D-allulose or gemfibrozil, decreased sterol response element binding protein 1 and sterol response element binding protein 2 expression relative to cells not exposed to oleic acid, while peroxisome proliferator-activated receptor γ expression did not change. These results indicate that D-alluose mimics gemfibrozil effects on lipid content in HepG2 cells by promoting fatty acid β-oxidation via PPARα .

Olanzapine exposure disordered lipid metabolism, gut microbiota and behavior in zebrafish (Danio rerio).

Olanzapine (OLZ) is widely used in the treatment of schizophrenia, and its metabolic side effects have garnered significant attention in recent years. Despite this, the specific side effects of OLZ and the underlying mechanisms remain inadequately understood. To address this gap, zebrafish (Danio rerio) were exposed to OLZ at concentrations of 35.5, 177.5, and 355.5μg/L. The results indicated that exposure to OLZ significantly increased body weight, total cholesterol (TC), low-density lipoprotein (LDL), and triglycerides (TG). Histological analysis revealed notable lipid accumulation in the liver. Furthermore, lipid synthesis genes, including sterol regulatory element binding protein (srebp), acetyl CoA carboxylase (acc), and fatty acid synthesis gene (fas), were up-regulated. In contrast, genes related to lipid decomposition, such as lipoprotein lipase (lpl), hormone-sensitive triglyceride lipase (hsl), and carnitine palmitoyltransferase 1b (cpt1b), were down-regulated. Subsequent analysis of zebrafish behavior showed reduced motor activity, sociability, and anxiety-like behavior in OLZ-exposed zebrafish, consistent with the results of neurotransmitter related gene expression. Following OLZ treatment, the expression of tryptophan hydroxylase (tph), tyrosine hydroxylase (th), dopamine transporter (dat), glutaminase (glsa), and glutamic acid decarboxylase 1b (gad1b) was upregulated. Additionally, the diversity of intestinal flora decreased after OLZ exposure, and the structure of the intestinal microbiota changed significantly compared to the control group. At the genus level, the abundance of Plesiomonas was upregulated, while the abundances of Bacillus and Cetobacterium were downregulated in the OLZ-exposed group. Furthermore, the results of the correlation analysis indicated that lipid metabolism and behavioral changes were closely associated with the microbiota. This study clarified the side effects of OLZ, and also provided a basis for the reasonable discharge concentration of OLZ in water and clinical drug use.

Pancreatic expression of CPT1A is essential for whole body glucose homeostasis by supporting glucose-stimulated insulin secretion.

Pancreatic islet β-cells express the Cpt1a gene, which encodes the enzyme carnitine palmitoyltransferase 1A (CPT1A), an enzyme that facilitates entry of long chain fatty acids into the mitochondria. Because fatty acids are required for glucose-stimulated insulin secretion, we tested the hypothesis that CPT1A is essential to support islet β-cell function and mass. In this study, we describe genetic deletion of Cpt1a in pancreatic tissue (Cpt1aPdx1-/-) using C57BL/6J mice. Islet morphology, β-cell transcription factor abundance, islet ATP levels, GLUT2 abundance, and expression of the de-differentiation marker ALDH1A3 were analyzed by immunofluorescent staining. Glucose and insulin tolerance were assessed to investigate the metabolic status of genetic reductions in Cpt1a. Glucose-stimulated insulin secretion was evaluated in vivo and in isolated islets ex vivo by perifusion. Pancreatic deletion of Cpt1a reduced glucose tolerance but did not alter insulin sensitivity. Glucose-stimulated insulin secretion was reduced both in vivo and in islets isolated from Cpt1aPdx1-/- mice relative to control islets. Pancreatic islets from Cpt1aPdx1-/- mice displayed elevations in ALDH1A3, a marker of de-differentiation, but no reduction in nuclear abundance of the β-cell transcription factors MafA and Nkx6.1 or the GLUT2 glucose transporter. However, intracellular ATP abundance was markedly decreased in islets isolated from Cpt1aPdx1-/- relative to littermate control mice. We conclude that there is an important physiological role for pancreatic CPT1A to maintain whole-body glucose homeostasis by supporting glucose-stimulated insulin secretion and maintaining intracellular ATP levels in male mice.

Exploring fatty acid metabolism in Alzheimer’s disease: the key role of CPT1A

Alzheimer’s disease (AD) is a severe neurodegenerative disease, and the most common type of dementia, with symptoms of progressive cognitive dysfunction and behavioral impairment. Studying the pathogenesis of AD and exploring new targets for the prevention and treatment of AD is a very worthwhile challenge. Accumulating evidence has highlighted the effects of fatty acid metabolism on AD. In this study, fatty acid metabolism was used as an entry point to understand the pathogenesis of AD and identify new targets. After identifying differentially expressed genes, multiple machine learning algorithms, carnitine palmitoyltransferase 1 A (CPT1A) was identified as the key gene for fatty acid metabolism in AD. Further single nucleus RNA sequencing analysis were performed, and the GSEA results showed that the fatty acid β-oxidation pathway was enriched only in astrocytes, and the fatty acid β-oxidation pathway was down-regulated in the AD astrocytes compared to the CN astrocytes, while CPT1A was specifically downregulated in astrocytes of AD, which was confirmed in vitro experiment subsequently, and decreased expression level of CPT1A would lead to abnormal lipid metabolism, which shapes astrocyte reactivity and injury, neuroinflammatory, and thus affects AD pathogenesis. Our findings report the involvement of CPT1A in AD. We confirm that the primary role of astrocytes for fatty acid β-oxidation, and CPT1A is localized in astrocytes. Downregulated CPT1A could be a novel potential target for the prevention and treatment of AD. Our study provides strong evidence for the involvement of fatty acid metabolism in the pathogenesis of AD.

Etomoxir suppresses the expression of PPARgamma2 and inhibits the thermogenic gene induction of brown adipocytes through pathways other than β-oxidation inhibition.

Brown adipocytes are characterized by a high abundance of mitochondria, allowing them to consume fatty acids for heat production. Increasing the number of brown adipocytes is considered a promising strategy for combating obesity. However, the molecular mechanisms underlying their differentiation remain poorly understood. In this study, we demonstrate that etomoxir, an inhibitor of Carnitine Palmitoyltransferase 1 (CPT1), inhibits their differentiation through mechanisms independent of β-oxidation inhibition. In the presence of etomoxir during brown adipocyte differentiation, reduced expression of the thermogenic gene UCP1 and decreased lipid droplets formation were observed. Furthermore, a transient reduction in the expression of PPARγ2, a critical factor in adipocyte differentiation, was also observed in the presence of etomoxir. These findings suggest the presence of a regulatory mechanism that specifically enhances PPARγ2 expression during brown adipocyte differentiation, thereby modulating thermogenic gene expression.

Impact of Soybean Bioactive Peptides on Growth, Lipid Metabolism, Antioxidant Ability, Molecular Responses, and Gut Microbiota of Oriental River Prawn (Macrobrachium nipponense) Fed with a Low-Fishmeal Diet.

The substitution of fishmeal with high-level soybean meal in the diet of crustaceans usually induces lipid accumulation and oxidative stress in the hepatopancreas. Therefore, it is essential to alleviate these adverse effects. In the present study, SBPs were used to alleviate the negative effects of a fishmeal decrease on the growth performance, lipid metabolism, antioxidant capacity, and gut microbiota of oriental river prawn (Macrobrachium nipponense) in an 8-week feeding trial. Three isonitrogenic and isolipidic diets were prepared as follows: R (reference diet with 32% fishmeal), CT (control diet with 22% fishmeal), and SBP (22% fishmeal with 1.25 g/kg soybean bioactive peptides). The prawns (initial biomass per tank 17 g) were randomly divided into three groups with four replicates. The results showed that the low-fishmeal diet induced the following: (1) the inhibition of growth performance and survival of prawns; (2) an increase in triglyceride content in the hepatopancreas and hemolymph and downregulation of carnitine palmitoyl transferase 1 (cpt1) gene expression; (3) a reduction in antioxidant enzymes' activities and their genes expression levels and an increase malondialdehyde (MDA) content; and (4) an increase in the abundance of the conditional pathogen Pseudomonas in the gut. SBPs supplementation in the CT diet effectively alleviated most of the above adverse effects. SBPs enhanced inducible nitric oxide synthase (iNOS) activity to synthesize nitric oxide (NO) by activating the imd-relish pathway. Most importantly, SBPs increased the potential probiotic Rikenellaceae_RC9_gut_group abundance and decreased the abundance of the conditional pathogen Pseudomonas in the gut. In conclusion, SBPs supplementation can improve low-fishmeal-diet-induced growth inhibition by regulating the gut microbiota composition to ameliorate lipid deposition and oxidative stress and strengthen immune status in oriental river prawn.