Liver X receptors in lipid signalling and membrane homeostasis

IRX4204 Induces Senescence and Cell Death in HER2-positive Breast Cancer and Synergizes with Anti-HER2 Therapy

PURPOSE

Rexinoids, agonists of nuclear retinoid X receptor (RXR), have been used for the treatment of cancers and are well tolerated in both animals and humans. However, the usefulness of rexinoids in treatment of breast cancer remains unknown. This study examines the efficacy of IRX4204, a highly specific rexinoid, in breast cancer cell lines and preclinical models to identify a biomarker for response and potential mechanism of action.

EXPERIMENTAL DESIGN

IRX4204 effects on breast cancer cell growth and viability were determined using cell lines, syngeneic mouse models, and primary patient-derived xenograft (PDX) tumors. In vitro assays of cell cycle, apoptosis, senescence, and lipid metabolism were used to uncover a potential mechanism of action. Standard anti-HER2 therapies were screened in combination with IRX4204 on a panel of breast cancer cell lines to determine drug synergy.

RESULTS

IRX4204 significantly inhibits the growth of HER2-positive breast cancer cell lines, including trastuzumab and lapatinib-resistant JIMT-1 and HCC1954. Treatment with IRX4204 reduced tumor growth rate in the MMTV-ErbB2 mouse and HER2-positive PDX model by 49% and 44%, respectively. Mechanistic studies revealed IRX4204 modulates lipid metabolism and induces senescence of HER2-positive cells. In addition, IRX4204 demonstrates additivity and synergy with HER2-targeted mAbs, tyrosine kinase inhibitors, and antibody-drug conjugates.

CONCLUSIONS

These findings identify HER2 as a biomarker for IRX4204 treatment response and demonstrate a novel use of RXR agonists to synergize with current anti-HER2 therapies. Furthermore, our results suggest that RXR agonists can be useful for the treatment of anti-HER2 resistant and metastatic HER2-positive breast cancer.

Multi-layered effects of Panax notoginseng on immune system

Recent research has demonstrated the immunomodulatory potential of Panax notoginseng in the treatment of chronic inflammatory diseases and cerebral hemorrhage, suggesting its significance in clinical practice. Nevertheless, the complex immune activity of various components has hindered a comprehensive understanding of the immune-regulating properties of Panax notoginseng, impeding its broader utilization. This review evaluates the effect of Panax notoginseng to various types of white blood cells, elucidates the underlying mechanisms, and compares the immunomodulatory effects of different Panax notoginseng active fractions, aiming to provide the theory basis for future immunomodulatory investigation.

Discovery and Optimization of N-Arylated Tetracyclic Dicarboximides That Target Primary Glioma Stem-like Cells

We recently discovered a novel N-aryl tetracyclic dicarboximide MM0299 (1) with robust activity against glioma stem-like cells that potently and selectively inhibits lanosterol synthase leading to the accumulation of the toxic shunt metabolite 24(S),25-epoxycholesterol. Herein, we delineate a systematic and comprehensive SAR study that explores the structural space surrounding the N-aryl tetracyclic dicarboximide scaffold. A series of 100 analogs were synthesized and evaluated for activity against the murine glioma stem-like cell line Mut6 and for metabolic stability in mouse liver S9 fractions. This study led to several analogs with single-digit nanomolar activity in Mut6 glioblastoma cells that were metabolically stable in S9 fractions. In vivo pharmacokinetic analysis of selected analogs identified compound 52a (IC50 = 63 nM; S9 T1/2 > 240 min) which was orally available (39% plasma; 58% brain) and displayed excellent brain exposure. Chronic oral dosing of 52a during a 2-week tolerability study indicated no adverse effect on body weight nor signs of hematologic, liver, or kidney toxicity.

Therapeutic potential of oleic acid supplementation in myotonic dystrophy muscle cell models

BACKGROUND

We recently reported that upregulation of Musashi 2 (MSI2) protein in the rare neuromuscular disease myotonic dystrophy type 1 contributes to the hyperactivation of the muscle catabolic processes autophagy and UPS through a reduction in miR-7 levels. Because oleic acid (OA) is a known allosteric regulator of MSI2 activity in the biogenesis of miR-7, here we sought to evaluate endogenous levels of this fatty acid and its therapeutic potential in rescuing cell differentiation phenotypes in vitro. In this work, four muscle cell lines derived from DM1 patients were treated with OA for 24 h, and autophagy and muscle differentiation parameters were analyzed.

RESULTS

We demonstrate a reduction of OA levels in different cell models of the disease. OA supplementation rescued disease-related phenotypes such as fusion index, myotube diameter, and repressed autophagy. This involved inhibiting MSI2 regulation of direct molecular target miR-7 since OA isoschizomer, elaidic acid (EA) could not cause the same rescues. Reduction of OA levels seems to stem from impaired biogenesis since levels of the enzyme stearoyl-CoA desaturase 1 (SCD1), responsible for converting stearic acid to oleic acid, are decreased in DM1 and correlate with OA amounts.

CONCLUSIONS

For the first time in DM1, we describe a fatty acid metabolism impairment that originated, at least in part, from a decrease in SCD1. Because OA allosterically inhibits MSI2 binding to molecular targets, reduced OA levels synergize with the overexpression of MSI2 and contribute to the MSI2 > miR-7 > autophagy axis that we proposed to explain the muscle atrophy phenotype.

Association of Di(2-ethylhexyl) Terephthalate and Its Metabolites with Nonalcoholic Fatty Liver Disease: An Epidemiology and Toxicology Study

As an alternative plasticizer to conventional phthalates, di(2-ethylhexyl) terephthalate (DEHTP) has attracted considerable concerns, given its widespread detection in the environment and humans. However, the potential toxicity, especially liver toxicity, posed by DEHTP remains unclear. In this study, based on the 2017-2018 National Health and Nutrition Examination Survey, two metabolites of DEHTP, i.e., mono(2-ethyl-5-hydroxyhexyl) terephthalate (MEHHTP) and mono(2-ethyl-5-carboxypentyl) terephthalate (MECPTP), were found to be present in the urine samples of nearly all representative U.S. adults. Moreover, a positive linear correlation was observed between the concentrations of the two metabolites and the risk of nonalcoholic fatty liver disease (NAFLD) in the population. Results of weighted quantile sum and Bayesian kernel machine regression indicated that MEHHTP contributed a greater weight to the risk of NAFLD in comparison with 12 conventional phthalate metabolites. In vitro experiments with hepatocyte HepG2 revealed that MEHHTP exposure could increase lipogenic gene programs, thereby promoting a dose-dependent hepatic lipid accumulation. Activation of liver X receptor α may be an important regulator of MEHHTP-induced hepatic lipid disorders. These findings provide new insights into the liver lipid metabolism toxicity potential of DEHTP exposure in the population.

Investigation of Liver X Receptor Gene Variants and Oxysterol Dysregulation in Autism Spectrum Disorder

The NR1H2 gene produces the Liver X Receptor Beta (LXRB) protein, which is crucial for brain cholesterol metabolism and neuronal development. However, its involvement in autism spectrum disorder (ASD) remains largely unexplored, aside from animal studies. This study is the first to explore the potential link between autism and rs2695121/rs17373080 single nucleotide polymorphisms (SNPs) in the regulatory regions of NR1H2, known for their association with neuropsychiatric functions. Additionally, we assessed levels of oxysterols (24-Hydroxycholesterol, 25-Hydroxycholesterol, 27-Hydroxycholesterol), crucial ligands of LXR, and lipid profiles. Our cohort comprised 107 children with ASD and 103 healthy children aged 2-18 years. Clinical assessment tools included the Childhood Autism Rating Scale, Autistic Behavior Checklist, and Repetitive Behavior Scale-Revised. Genotyping for SNPs was conducted using PCR-RFLP. Lipid profiles were analyzed with Beckman Coulter kits, while oxysterol levels were determined through liquid chromatography-tandem mass spectrometry. Significantly higher total cholesterol (p = 0.003), LDL (p = 0.008), and triglyceride (p < 0.001) levels were observed in the ASD group. 27-Hydroxycholesterol levels were markedly lower in the ASD group (p ≤ 0.001). ROC analysis indicated the potential of 27-Hydroxycholesterol to discriminate ASD diagnosis. The SNP genotype and allele frequencies were similar in both groups (p > 0.05). Our findings suggest that disturbances in oxysterol metabolism, previously linked to neurodegeneration, may constitute a risk factor for ASD and contribute to its heterogeneous phenotype.

Xanthohumol, a prenylated chalcone, regulates lipid metabolism by modulating the LXRα/RXR-ANGPTL3-LPL axis in hepatic cell lines and high-fat diet-fed zebrafish models

Angiopoietin-like 3 (ANGPTL3) acts as an inhibitor of lipoprotein lipase (LPL), impeding the breakdown of triglyceride-rich lipoproteins (TGRLs) in circulation. Targeting ANGPTL3 is considered a novel strategy for improving dyslipidemia and atherosclerotic cardiovascular diseases (ASCVD). Hops (Humulus lupulus L.) contain several bioactive prenylflavonoids, including xanthohumol (Xan), isoxanthohumol (Isoxan), 6-prenylnaringenin (6-PN), and 8-prenylnaringenin (8-PN), with the potential to manage lipid metabolism. The aim of this study was to investigate the lipid-lowering effects of Xan, the effective prenylated chalcone in attenuating ANGPTL3 transcriptional activity, both in vitro using hepatic cells and in vivo using zebrafish models, along with exploring the underlying mechanisms. Xan (10 and 20 μM) significantly reduced ANGPTL3 mRNA and protein expression in HepG2 and Huh7 cells, leading to a marked decrease in secreted ANGPTL3 proteins via hepatic cells. In animal studies, orally administered Xan significantly alleviated plasma triglyceride (TG) and cholesterol levels in zebrafish fed a high-fat diet. Furthermore, it reduced hepatic ANGPTL3 protein levels and increased LPL activity in zebrafish models, indicating its potential to modulate lipid profiles in circulation. Furthermore, molecular docking results predicted that Xan exhibits a higher binding affinity to interact with liver X receptor α (LXRα) and retinoic acid X receptor (RXR) than their respective agonists, T0901317 and 9-Cis-retinoic acid (9-Cis-RA). We observed that Xan suppressed hepatic ANGPTL3 expression by antagonizing the LXRα/RXR-mediated transcription. These findings suggest that Xan ameliorates dyslipidemia by modulating the LXRα/RXR-ANGPTL3-LPL axis. Xan represents a novel potential inhibitor of ANGPTL3 for the prevention or treatment of ASCVD.

A review of the role of transcription factors in regulating adipogenesis and lipogenesis in beef cattle

In the past few decades, genomic selection and other refined strategies have been used to increase the growth rate and lean meat production of beef cattle. Nevertheless, the fast growth rates of cattle breeds are often accompanied by a reduction in intramuscular fat (IMF) deposition, impairing meat quality. Transcription factors play vital roles in regulating adipogenesis and lipogenesis in beef cattle. Meanwhile, understanding the role of transcription factors in regulating adipogenesis and lipogenesis in beef cattle has gained significant attention to increase IMF deposition and meat quality. Therefore, the aim of this paper was to provide a comprehensive summary and valuable insight into the complex role of transcription factors in adipogenesis and lipogenesis in beef cattle. This review summarizes the contemporary studies in transcription factors in adipogenesis and lipogenesis, genome-wide analysis of transcription factors, epigenetic regulation of transcription factors, nutritional regulation of transcription factors, metabolic signalling pathways, functional genomics methods, transcriptomic profiling of adipose tissues, transcription factors and meat quality and comparative genomics with other livestock species. In conclusion, transcription factors play a crucial role in promoting adipocyte development and fatty acid biosynthesis in beef cattle. They control adipose tissue formation and metabolism, thereby improving meat quality and maintaining metabolic balance. Understanding the processes by which these transcription factors regulate adipose tissue deposition and lipid metabolism will simplify the development of marbling or IMF composition in beef cattle.

Reprogramming of the LXRα Transcriptome Sustains Macrophage Secondary Inflammatory Responses

Macrophages regulate essential aspects of innate immunity against pathogens. In response to microbial components, macrophages activate primary and secondary inflammatory gene programs crucial for host defense. The liver X receptors (LXRα, LXRβ) are ligand-dependent nuclear receptors that direct gene expression important for cholesterol metabolism and inflammation, but little is known about the individual roles of LXRα and LXRβ in antimicrobial responses. Here, the results demonstrate that induction of LXRα transcription by prolonged exposure to lipopolysaccharide (LPS) supports inflammatory gene expression in macrophages. LXRα transcription is induced by NF-κB and type-I interferon downstream of TLR4 activation. Moreover, LPS triggers a reprogramming of the LXRα cistrome that promotes cytokine and chemokine gene expression through direct LXRα binding to DNA consensus sequences within cis-regulatory regions including enhancers. LXRα-deficient macrophages present fewer binding of p65 NF-κB and reduced histone H3K27 acetylation at enhancers of secondary inflammatory response genes. Mice lacking LXRα in the hematopoietic compartment show impaired responses to bacterial endotoxin in peritonitis models, exhibiting reduced neutrophil infiltration and decreased expansion and inflammatory activation of recruited F4/80lo-MHC-IIhi peritoneal macrophages. Together, these results uncover a previously unrecognized function for LXRα-dependent transcriptional cis-activation of secondary inflammatory gene expression in macrophages and the host response to microbial ligands.

Toosendanin induces hepatotoxicity via disrupting LXRα/Lipin1/SREBP1 mediated lipid metabolism

Toosendanin (TSN) is the main active compound derived from Melia toosendan Sieb et Zucc with various bioactivities. However, liver injury was observed in TSN limiting its clinical application. Lipid metabolism plays a crucial role in maintaining cellular homeostasis, and its disruption is also essential in TSN-induced hepatotoxicity. This study explored the hepatotoxicity caused by TSN in vitro and in vivo. The lipid droplets were significantly decreased, accompanied by a decrease in fatty acid transporter CD36 and crucial enzymes in the lipogenesis including ACC and FAS after the treatment of TSN. It was suggested that TSN caused lipid metabolism disorder in hepatocytes. TOFA, an allosteric inhibitor of ACC, could partially restore cell survival via blocking malonyl-CoA accumulation. Notably, TSN downregulated the LXRα/Lipin1/SREBP1 signaling pathway. LXRα activation improved cell survival and intracellular neutral lipid levels, while SREBP1 inhibition aggravated the cell damage and caused a further decline in lipid levels. Male Balb/c mice were treated with TSN (5, 10, 20 mg/kg/d) for 7 days. TSN exposure led to serum lipid levels aberrantly decreased. Moreover, the western blotting results showed that LXRα/Lipin1/SREBP1 inhibition contributed to TSN-induced liver injury. In conclusion, TSN caused lipid metabolism disorder in liver via inhibiting LXRα/Lipin1/SREBP1 signaling pathway.

Theabrownin from Qingzhuan tea prevents high-fat diet-induced MASLD via regulating intestinal microbiota

The aim of this study was to investigate whether the therapeutic effect of theabrownin extracted from Qingzhuan tea (QTB) on metabolic dysfunction-associated steatosis liver disease (MASLD) is related to the regulation of intestinal microbiota and its metabolite short-chain fatty acids (SCFAs). Mice were divided into four groups and received normal diet (ND), high-fat diet (HFD) and HFD+QTB (180, 360 mg/kg) for 8 weeks. The results showed that QTB significantly reduced the body weight of HFD mice, ameliorated liver lipid and dyslipidemia, and increased the level of intestinal SCFAs in HFD mice. The results of 16 S rRNA showed that the relative abundance of Bacteroides, Blautia and Lachnoclostridium and their main metabolites acetate and propionate were significantly increased after QTB intervention. The relative abundance of Colidextribacter, Faecalibaculum and Lactobacillus was significantly reduced. QTB can also significantly up-regulate the expression of ATGL, PPARα, FFAR2 and FFAR3, and inhibit the expression of LXRα, SREBP-1c, FAS and HMGCR genes. This makes it possible to act as a prebiotic to prevent MASLD.

Squalene-epoxidase-catalyzed 24(S),25-epoxycholesterol synthesis promotes trained-immunity-mediated antitumor activity

The importance of trained immunity in antitumor immunity has been increasingly recognized, but the underlying metabolic regulation mechanisms remain incompletely understood. In this study, we find that squalene epoxidase (SQLE), a key enzyme in cholesterol synthesis, is required for β-glucan-induced trained immunity in macrophages and ensuing antitumor activity. Unexpectedly, the shunt pathway, but not the classical cholesterol synthesis pathway, catalyzed by SQLE, is required for trained immunity induction. Specifically, 24(S),25-epoxycholesterol (24(S),25-EC), the shunt pathway metabolite, activates liver X receptor and increases chromatin accessibility to evoke innate immune memory. Meanwhile, SQLE-induced reactive oxygen species accumulation stabilizes hypoxia-inducible factor 1α protein for metabolic switching into glycolysis. Hence, our findings identify 24(S),25-EC as a key metabolite for trained immunity and provide important insights into how SQLE regulates trained-immunity-mediated antitumor activity.

Liver X receptor agonist upregulates LPCAT3 in human aortic endothelial cells

Objective

Endothelial cells (ECs) play an important role in tissue homeostasis. Recently, EC lipid metabolism has emerged as a regulator of EC function. The liver X receptors (LXRs) are involved in the transcriptional regulation of genes involved in lipid metabolism and have been identified as a potential target in cardiovascular disease. We aimed to decipher the role of LXRs in the regulation of lipid metabolism in human aortic endothelial cells.

Approach and Results

Lipid composition analysis of endothelial cells treated with the LXR agonist T0901317 revealed that LXR activation increased the proportion of polyunsaturated fatty acids (PUFAs) and decreased the proportion of saturated fatty acids. The LXR agonist decreased the uptake of fatty acids (FAs) by ECs. This effect was abolished by LXRα silencing. LXR activation increased the activity and the expression of lysophosphatidylcholine acyltransferase, LPCAT3, which is involved in the turnover of FAs at the sn-2 position of phospholipids. Transcriptomic analysis also revealed that LXRs increased the expression of key genes involved in the synthesis of PUFAs, including FA desaturase one and 2, FA elongase 5 and fatty acid synthase. Subsequently, the LXR agonist increased PUFA synthesis and enhanced arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid content in the EC phospholipids. Modification of the FA composition of ECs by LXRs led to a decrease of arachidonate and linoleate derived prostaglandins synthesis and release. No change on markers of inflammation induced by plasma from sickle cell patient were observed in presence of LXR agonist.

Conclusion

These results identify LXR as a key regulator of lipid metabolism in human aortic endothelial cells and a direct effect of LXR agonist on lysophosphatidylacyl transferase (LPCAT3).

LXR agonism for CNS diseases: promises and challenges

The unfavorable prognosis of many neurological conditions could be attributed to limited tissue regeneration in central nervous system (CNS) and overwhelming inflammation, while liver X receptor (LXR) may regulate both processes due to its pivotal role in cholesterol metabolism and inflammatory response, and thus receives increasing attentions from neuroscientists and clinicians. Here, we summarize the signal transduction of LXR pathway, discuss the therapeutic potentials of LXR agonists based on preclinical data using different disease models, and analyze the dilemma and possible resolutions for clinical translation to encourage further investigations of LXR related therapies in CNS disorders.

C1q/Tumor Necrosis Factor-Related Protein-9 Enhances Macrophage Cholesterol Efflux and Improves Reverse Cholesterol Transport via AMPK Activation

Cholesterol efflux from foam cells in atherosclerotic plaques is crucial for reverse cholesterol transport (RCT), an important antiatherogenic event. ATP-binding cassette (ABC) transporters, ABCA1 and ABCG1, are key receptors in the cholesterol efflux pathway. C1q/tumor necrosis factor-related protein-9 (CTRP9) is a newly discovered adipokine and exhibits an atheroprotective activity. However, the role of CTRP9 in RCT still remains unknown. In this work, we investigated the effect of subcutaneous administration of CTRP9 protein on RCT and atherosclerotic lesion formation in ApoE-/- mice fed with a high-fat diet. CTRP9-dependent regulation of cholesterol efflux and ABC transporters in RAW 264.7 foam cells was determined. Our results showed that CTRP9 protein decreased atherosclerotic lesions, increased cholesterol efflux, and upregulated liver ABCA1 and ABCG1 expression in ApoE-/- mice. CTRP9 treatment dose-dependently increased mRNA and protein expression of ABCA1, ABCG1, and LXR-α in RAW 264.7 foam cells. Moreover, the expression and phosphorylation of AMPK was potentiated upon CTRP9 treatment. Notably, CTRP9-induced cholesterol efflux and upregulation of ABCA, ABCG1, and LXR-α were impaired when AMPK was knocked down. AMPK depletion restored cholesterol accumulation in CTRP9-treated RAW 264.7 cells. Taken together, subcutaneous injection is an effective novel delivery route for CTRP9 protein, and exogenous CTRP9 can facilitate cholesterol efflux and promote RCT in an animal model of atherosclerosis. The atheroprotective activity of CTRP9 is mediated through the activation of AMPK signaling.

Future therapeutic perspectives in nonalcoholic fatty liver disease: a focus on nuclear receptors, a promising therapeutic target

Non-alcoholic fatty liver disease (NAFLD) is a major public health problem worldwide, with an increasing incidence, secondary to the increasing incidence of obesity and diabetes, from a very young age. It is associated with metabolic and cardiovascular disorders, as components of the metabolic syndrome (MS). NAFLD is the hepatic manifestation of MS. The pathogenesis of the disease is multifactorial and complex, involving genetic, metabolic, but also environmental factors. Currently, nuclear receptors (NRs) represent a promising therapeutic target in the treatment of non-alcoholic steatohepatitis (NASH). Of these, the most studied receptor was the liver X receptor (LXR), which would have great potential in the treatment of metabolic diseases, namely hypercholesterolemia, atherosclerosis, and NAFLD. However, the therapeutic use of NRs is restricted in medical practice for two reasons: limited knowledge of the structure of the receptor and its inability to modulate certain actions in the target organs and genes. One problem is the understanding of the function and structure of the N-terminal domain which has a major transcriptional activation function (AF1).

Research progress, challenges and perspectives of phospholipids metabolism in the LXR‑LPCAT3 signaling pathway and its relation to NAFLD (Review)

Phospholipids (PLs) are principle constituents of biofilms, with their fatty acyl chain composition significantly impacting the biophysical properties of membranes, thereby influencing biological processes. Recent studies have elucidated that fatty acyl chains, under the enzymatic action of lyso‑phosphatidyl‑choline acyltransferases (LPCATs), expedite incorporation into the sn‑2 site of phosphatidyl‑choline (PC), profoundly affecting pathophysiology. Accumulating evidence suggests that alterations in LPCAT activity are implicated in various diseases, including non‑alcoholic fatty liver disease (NAFLD), hepatitis C, atherosclerosis and cancer. Specifically, LPCAT3 is instrumental in maintaining systemic lipid homeostasis through its roles in hepatic lipogenesis, intestinal lipid absorption and lipoprotein secretion. The liver X receptor (LXR), pivotal in lipid homeostasis, modulates cholesterol, fatty acid (FA) and PL metabolism. LXR's capacity to modify PL composition in response to cellular sterol fluctuations is a vital mechanism for protecting biofilms against lipid stress. Concurrently, LXR activation enhances LPCAT3 expression on cell membranes and elevates polyunsaturated PL levels. This activation can ameliorate saturated free FA effects in vitro or endoplasmic reticulum stress in vivo due to lipid accumulation in hepatic cells. Pharmacological interventions targeting LXR, LPCAT and membrane PL components could offer novel therapeutic directions for NAFLD management. The present review primarily focused on recent advancements in understanding the LPCAT3 signaling pathway's role in lipid metabolism related to NAFLD, aiming to identify new treatment targets for the disease.

Adipose tissue peroxisomal lipid synthesis orchestrates obesity and insulin resistance through LXR-dependent lipogenesis

OBJECTIVE

Adipose tissue mass is maintained by a balance between lipolysis and lipid storage. The contribution of adipose tissue lipogenesis to fat mass, especially in the setting of high-fat feeding, is considered minor. Here we investigated the effect of adipose-specific inactivation of the peroxisomal lipid synthetic protein PexRAP on fatty acid synthase (FASN)-mediated lipogenesis and its impact on adiposity and metabolic homeostasis.

METHODS

To explore the role of PexRAP in adipose tissue, we metabolically phenotyped mice with adipose-specific knockout of PexRAP. Bulk RNA sequencing was used to determine transcriptomic responses to PexRAP deletion and 14C-malonyl CoA allowed us to measure de novo lipogenic activity in adipose tissue of these mice. In vitro cell culture models were used to elucidate the mechanism of cellular responses to PexRAP deletion.

RESULTS

Adipose-specific PexRAP deletion promoted diet-induced obesity and insulin resistance through activation of de novo lipogenesis. Mechanistically, PexRAP inactivation inhibited the flux of carbons to ethanolamine plasmalogens. This increased the nuclear PC/PE ratio and promoted cholesterol mislocalization, resulting in activation of liver X receptor (LXR), a nuclear receptor known to be activated by increased intracellular cholesterol. LXR activation led to increased expression of the phospholipid remodeling enzyme LPCAT3 and induced FASN-mediated lipogenesis, which promoted diet-induced obesity and insulin resistance.

CONCLUSIONS

These studies reveal an unexpected role for peroxisome-derived lipids in regulating LXR-dependent lipogenesis and suggest that activation of lipogenesis, combined with dietary lipid overload, exacerbates obesity and metabolic dysregulation.

Cav3.1 T-type calcium channel blocker NNC 55-0396 reduces atherosclerosis by increasing cholesterol efflux

Calcium channel blockers (CCBs) are commonly used as antihypertensive agents. While certain L-type CCBs exhibit antiatherogenic effects, the impact of Cav3.1 T-type CCBs on antiatherogenesis and lipid metabolism remains unexplored. NNC 55-0396 (NNC) is a highly selective blocker of T-type calcium channels (Cav3.1 channels). We investigated the effects of NNC on relevant molecules and molecular mechanisms in human THP-1 macrophages. Cholesterol efflux, an indicator of reverse cholesterol transport (RCT) efficiency, was assessed using [3H]-labeled cholesterol. In vivo, high cholesterol diet (HCD)-fed LDL receptor knockout (Ldlr-/-) mice, an atherosclerosis-prone model, underwent histochemical staining to analyze plaque burden. Treatment of THP-1 macrophages with NNC facilitated cholesterol efflux and reduced intracellular cholesterol accumulation. Pharmacological and genetic interventions demonstrated that NNC treatment or Cav3.1 knockdown significantly enhanced the protein expression of scavenger receptor B1 (SR-B1), ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), and liver X receptor alpha (LXRα) transcription factor. Mechanistic analysis revealed that NNC activates p38 and c-Jun N-terminal kinase (JNK) phosphorylation, leading to increased expression of ABCA1, ABCG1, and LXRα-without involving the microRNA pathway. LXRα isrequired for NNC-induced ABCA1 and ABCG1 expression. Administering NNC diminished atherosclerotic lesion area and lipid deposition in HCD-fed Ldlr-/- mice. NNC's anti-atherosclerotic effects, achieved through enhanced cholesterol efflux and inhibition of lipid accumulation, suggest a promising therapeutic approach for hypertensive patients with atherosclerosis. This research highlights the potential of Cav3.1 T-type CCBs in addressing cardiovascular complications associated with hypertension.

Transcriptomics analysis of the bovine endometrium during the perioestrus period

During the oestrous cycle, the bovine endometrium undergoes morphological and functional changes, which are regulated by alterations in the levels of oestrogen and progesterone and consequent changes in gene expression. To clarify these changes before and after oestrus, RNA-seq was used to profile the transcriptome of oestrus-synchronized beef heifers. Endometrial samples were collected from 29 animals, which were slaughtered in six groups beginning 12 h after the withdrawal of intravaginal progesterone releasing devices until seven days post-oestrus onset (luteal phase). The groups represented proestrus, early oestrus, metoestrus and early dioestrus (luteal phase). Changes in gene expression were estimated relative to gene expression at oestrus. Ingenuity Pathway Analysis (IPA) was used to identify canonical pathways and functional processes of biological importance. A total of 5,845 differentially expressed genes (DEGs) were identified. The lowest number of DEGs was observed at the 12 h post-oestrus time point, whereas the greatest number was observed at Day 7 post-oestrus onset (luteal phase). A total of 2,748 DEGs at this time point did not overlap with any other time points. Prior to oestrus, Neurological disease and Organismal injury and abnormalities appeared among the top IPA diseases and functions categories, with upregulation of genes involved in neurogenesis. Lipid metabolism was upregulated before oestrus and downregulated at 48h post-oestrus, at which point an upregulation of immune-related pathways was observed. In contrast, in the luteal phase the Lipid metabolism and Small molecule biochemistry pathways were upregulated.

Aerobic training with moderate or high doses of vitamin D improve liver enzymes, LXRα and PGC-1α levels in rats with T2DM

Dysregulation of key transcription factors involved in hepatic energy metabolism, such as peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) and liver X receptor alpha (LXRα), has been observed in T2DM. The present study aims to investigate the effects of aerobic training and vitamin D supplementation on liver enzyme levels and the levels of PGC-1α and LXRα proteins in hepatocytes, in a rat model of T2DM. The study involved 56 male Wistar rats, divided into two groups: one was non-diabetic and acted as a control group (n = 8), and the other had induced diabetes (n = 48). The diabetic rats were then split into six subgroups: two groups received high or moderate doses of vitamin D and aerobic training (D + AT + HD and D + AT + MD); two groups received high or moderate doses of vitamin D alone (D + HD and D + MD); one group underwent aerobic training with vehicle (sesame oil; D + AT + oil), and one group was a diabetic control receiving only sesame oil (oil-receiving). The D + AT + HD and D + HD groups received 10,000 IU of vitamin D, while the D + AT + MD and D + MD groups received 5000 IU of vitamin D once a week by injection. The D + AT + oil group and the sham group received sesame oil. After eight weeks of treatment, body weight, BMI, food intake, serum insulin, glucose, 25-hydroxyvitamin D, ALT, AST, and visceral fat were measured. The levels of PGC-1α and LXRα proteins in the liver was assessed by western blotting. Statistical analysis was performed using the paired t-test, one-way analysis of variance (ANOVA), and the Tukey post hoc test at a significance level of P < 0.05. Body weight, food intake, and BMI decreased significantly in the D + AT + HD, D + AT + MD, D + AT + oil, D + HD, and D + MD groups with the highest reduction being observed in body weight and BMI in the D + AT + HD group. The D + AT + HD group exhibited the lowest levels of insulin, glucose, and HOMA-IR while the D + C group exhibited the highest levels among the diabetic groups. The D + AT + HD and D + AT + MD groups had lower levels of ALT and AST enzymes compared to the other groups with no significant difference between D + AT + HD and D + AT + MD. D + AT + HD (p = 0.001), D + AT + MD (p = 0.001), D + HD (p = 0.023), D + MD (p = 0.029), and D + AT + oil (p = 0.011) upregulated LXRα compared to D + C. Among these groups, D + AT + HD exhibited a more profound upregulation of LXRα than D + AT + MD, D + AT + oil, D + HD, and D + MD (p = 0.005; p = 0.002, p = 0.001, and p = 0.001, respectively). Similarly, D + AT + HD showed a more notable upregulation of PGC-1α compared to D + AT + oil, D + HD, and D + MD (p = 0.002; p = 0.001, and p = 0.001, respectively). Pearson correlation tests showed significant and negative correlations between serum 25-hydroxyvitamin levels and both visceral fat (r = - 0.365; p = 0.005) and HOMA-IR (r = - 0.118; p = 0.009); while positive and significant correlations between the liver-to-bodyweight ratio with both ALT and AST enzymes and also between QUICKI levels with LXRα (r = 0.578; p = 0.001) and PGC-1α (r = 0.628; p = 0.001). Combined administration of aerobic training and vitamin D supplementation potentially improves liver enzymes in type-2 diabetic rats that were simultaneous with upregulating the levels of PGC-1α and LXRα proteins in hepatocytes. These improvements were more significant when combining exercise with high-dose vitamin D supplementation. This study highlights the potential of this combination therapy as a new diabetes treatment strategy.

Unveiling global research trends and hotspots on mitochondria in NAFLD from 2000 to 2023: A bibliometric analysis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has garnered significant attention in the past decade as a prevalent chronic liver condition. Despite a growing body of evidence implicating mitochondria in NAFLD development, comprehensive bibliometric analyses within this research domain are scarce. This study aims to provide a thorough overview of the knowledge framework and key research areas related to mitochondria in the context of NAFLD, utilizing bibliometric techniques.

METHODS

A comprehensive search of publications on mitochondria in NAFLD from 2000 to 2023 was conducted using the Web of Science Core Collection database. VOSviewers, CiteSpace, and the R package "bibliometrix" were employed for a precise assessment of the literature.

RESULTS

Examining 2530 articles from 77 countries, primarily led by the United States and China, revealed a consistent increase in publications on mitochondria's role in NAFLD. Leading research institutions include the University of Coimbra, the University of Missouri, the Chinese Academy of Sciences, Fudan University, and Shanghai Jiao Tong University. Notably, the International Journal of Molecular Sciences emerged as the most popular journal, and Hepatology was the most frequently cited. With contributions from 14,543 authors, Michael Roden published the highest number of papers, and A. J. Samyal was the most frequently cocited author. Key focus areas include investigating mitochondrial mechanisms impacting NAFLD and developing therapeutic strategies targeting mitochondria. Emerging research hotspots are associated with keywords such as "inflammation," "mitochondrial dysfunction," "autophagy," "obesity," and "insulin resistance."

CONCLUSION

This study, the first comprehensive bibliometric analysis, synthesizes research trends and advancements in the role of mitochondria in NAFLD. Insights derived from this analysis illuminate current frontiers and emerging areas of interest, providing a valuable reference for scholars dedicated to mitochondrial studies.

Delineating the role of nuclear receptors in colorectal cancer, a focused review

Colorectal cancer (CRC) stands as one of the most prevalent form of cancer globally, causing a significant number of deaths, surpassing 0.9 million in the year 2020. According to GLOBOCAN 2020, CRC ranks third in incidence and second in mortality in both males and females. Despite extensive studies over the years, there is still a need to establish novel therapeutic targets to enhance the patients' survival rate in CRC. Nuclear receptors (NRs) are ligand-activated transcription factors (TFs) that regulate numerous essential biological processes such as differentiation, development, physiology, reproduction, and cellular metabolism. Dysregulation and anomalous expression of different NRs has led to multiple alterations, such as impaired signaling cascades, mutations, and epigenetic changes, leading to various diseases, including cancer. It has been observed that differential expression of various NRs might lead to the initiation and progression of CRC, and are correlated with poor survival outcomes in CRC patients. Despite numerous studies on the mechanism and role of NRs in this cancer, it remains of significant scientific interest primarily due to the diverse functions that various NRs exhibit in regulating key hallmarks of this cancer. Thus, modulating the expression of NRs with their agonists and antagonists, based on their expression levels, holds an immense prospect in the diagnosis, prognosis, and therapeutical modalities of CRC. In this review, we primarily focus on the role and mechanism of NRs in the pathogenesis of CRC and emphasized the significance of targeting these NRs using a variety of agents, which may represent a novel and effective strategy for the prevention and treatment of this cancer.

Cell-type-specific cis-regulatory divergence in gene expression and chromatin accessibility revealed by human-chimpanzee hybrid cells

Although gene expression divergence has long been postulated to be the primary driver of human evolution, identifying the genes and genetic variants underlying uniquely human traits has proven to be quite challenging. Theory suggests that cell-type-specific cis-regulatory variants may fuel evolutionary adaptation due to the specificity of their effects. These variants can precisely tune the expression of a single gene in a single cell-type, avoiding the potentially deleterious consequences of trans-acting changes and non-cell type-specific changes that can impact many genes and cell types, respectively. It has recently become possible to quantify human-specific cis-acting regulatory divergence by measuring allele-specific expression in human-chimpanzee hybrid cells-the product of fusing induced pluripotent stem (iPS) cells of each species in vitro. However, these cis-regulatory changes have only been explored in a limited number of cell types. Here, we quantify human-chimpanzee cis-regulatory divergence in gene expression and chromatin accessibility across six cell types, enabling the identification of highly cell-type-specific cis-regulatory changes. We find that cell-type-specific genes and regulatory elements evolve faster than those shared across cell types, suggesting an important role for genes with cell-type-specific expression in human evolution. Furthermore, we identify several instances of lineage-specific natural selection that may have played key roles in specific cell types, such as coordinated changes in the cis-regulation of dozens of genes involved in neuronal firing in motor neurons. Finally, using novel metrics and a machine learning model, we identify genetic variants that likely alter chromatin accessibility and transcription factor binding, leading to neuron-specific changes in the expression of the neurodevelopmentally important genes FABP7 and GAD1. Overall, our results demonstrate that integrative analysis of cis-regulatory divergence in chromatin accessibility and gene expression across cell types is a promising approach to identify the specific genes and genetic variants that make us human.

Laminaria japonica Aresch-Derived Fucoidan Ameliorates Hyperlipidemia by Upregulating LXRs and Suppressing SREBPs

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide, and hyperlipidemia is one major inducing factor of CVD. It is worthy to note that fucoidans are reported to have hypolipidemic activity with species specificity; however, the underlying mechanisms of action are far from clarification. This study is aimed at investigating the plasma lipid-lowering mechanisms of the fucoidan from L. japonica Aresch by detecting the levels of hepatic genes that are involved in lipid metabolism. Our results demonstrated that the fucoidan F3 significantly lowered total cholesterol and triglyceride in C57BL/6J mice fed a high-fat diet. In the mouse liver, fucoidan F3 intervention significantly increased the gene expression of peroxisome proliferator-activated receptor (PPAR) α, liver X receptor (LXR) α and β, and ATP-binding cassette transporter (ABC) G1 and G8 and decreased the expression of proprotein convertase subtilisin/kexin type 9 (PCSK9), low-density lipoprotein receptor, cholesterol 7 alpha-hydroxylase A1, and sterol regulatory element-binding protein (SREBP) 1c and SREBP-2. These results demonstrated that the antihyperlipidemic effects of fucoidan F3 are related to its activation of PPARα and LXR/ABC signaling pathways and inactivation of SREBPs. In conclusion, fucoidan F3 may be explored as a potential compound for prevention or treatment of lipid disorders.

Sonic hedgehog-heat shock protein 90β axis promotes the development of nonalcoholic steatohepatitis in mice

Sonic hedgehog (SHH) and heat shock protein 90β (HSP90β) have been implicated in nonalcoholic steatohepatitis (NASH) but their molecular mechanisms of action remain elusive. We find that HSP90β is a key SHH downstream molecule for promoting NASH process. In hepatocytes, SHH reduces HSP90β ubiquitylation through deubiquitylase USP31, thus preventing HSP90β degradation and promoting hepatic lipid synthesis. HSP90β significantly increases in NASH mouse model, leading to secretion of exosomes enriched with miR-28-5p. miR-28-5p directly targetes and decreases Rap1b levels, which in turn promotes NF-κB transcriptional activity in macrophages and stimulates the expression of inflammatory factors. Genetic deletion, pharmacological inhibition of the SHH-HSP90β axis, or delivery of miR-28-5p to macrophages in the male mice liver, impairs NASH symptomatic development. Importantly, there is a markedly higher abundance of miR-28-5p in NASH patient sera. Taken together, the SHH-HSP90β-miR-28-5p axis offers promising therapeutic targets against NASH, and serum miR-28-5p may serve as a NASH diagnostic biomarker.

Prostate Cancer and the Mevalonate Pathway

Antineoplastic therapies for prostate cancer (PCa) have traditionally centered around the androgen receptor (AR) pathway, which has demonstrated a significant role in oncogenesis. Nevertheless, it is becoming progressively apparent that therapeutic strategies must diversify their focus due to the emergence of resistance mechanisms that the tumor employs when subjected to monomolecular treatments. This review illustrates how the dysregulation of the lipid metabolic pathway constitutes a survival strategy adopted by tumors to evade eradication efforts. Integrating this aspect into oncological management could prove valuable in combating PCa.

Effects of Clostridium tyrobutyricum on Lipid Metabolism, Intestinal Barrier Function, and Gut Microbiota in Obese Mice Induced by High-Fat Diet

Obesity and its complications constitute a main threat to global human health. The purpose of this investigation was to explore the influences of Clostridium tyrobutyricum (Ct) on lipid metabolism, intestinal barrier function, and intestinal microbiome in obese mice induced by a high-fat diet (HFD). After establishing the obesity model, 107 CFU/mL and 108 CFU/mL C. tyrobutyricum were used to intervene in HFD-fed mice by gavage for six weeks, and indexes related to obesity were measured. In the liver of HFD-fed mice, the results revealed that C. tyrobutyricum reduced liver weight and the levels of triglyceride (TG), total cholesterol (TC), and nonesterified fatty acid (NEFA), along with decreasing red lipid droplets and fat vacuoles. After C. tyrobutyricum intervention, the mRNA expression of peroxisome proliferator-activated receptor-γ (PPARγ) was downregulated, and AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor-α (PPARα), adipose triglyceride lipase (ATGL), and hormone-sensitive lipase (HSL) were upregulated in the liver. Additionally, C. tyrobutyricum alleviated intestinal morphology injury caused by HFD, decreased the expression of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and IL-1β in the colon, and upregulated tight junction protein expression. In addition, 16S rRNA sequencing revealed that C. tyrobutyricum increases the diversity of intestinal microbiota. Overall, C. tyrobutyricum improved HFD-induced lipid metabolism disorders, preserved the intestinal barrier's integrity, and modulated the structure of the intestinal microbiome. These findings provide a novel insight into the role of C. tyrobutyricum as a probiotic in regulating lipid metabolism.

Activation of LXRs alleviates neuropathic pain-induced cognitive dysfunction by modulation of microglia polarization and synaptic plasticity via PI3K/AKT pathway

OBJECTIVE

Cognitive dysfunction is a common comorbidity in patients with chronic pain. Activation of Liver X receptors (LXRs) plays a potential role in improving cognitive disorders in central nervous diseases. In this study, we investigated the role of LXRs in cognitive deficits induced by neuropathic pain.

METHODS

We established the spared nerve injury (SNI) model to investigate pain-induced memory dysfunction. Pharmacological activation of LXRs with T0901317 or inhibition with GSK2033 was applied. PI3K inhibitor LY294002 was administered to explore the underlying mechanism of LXRs. Changes in neuroinflammation, microglia polarization, and synaptic plasticity were assessed using biochemical technologies.

RESULTS

We found that SNI-induced cognitive impairment was associated with reduced LXRβ expression, increased M1-phenotype microglia, decreased synaptic proteins, and inhibition of PI3K/AKT signaling pathway in the hippocampus. Activation of LXRs using T0901317 effectively alleviated SNI-induced cognitive impairment. Additionally, T0901317 promoted the polarization of microglia from M1 to M2, reduced pro-inflammatory cytokines, and upregulated synaptic proteins in the hippocampus. However, administration of GSK2033 or LY294002 abolished these protective effects of T0901317 in SNI mice.

CONCLUSIONS

LXRs activation alleviates neuropathic pain-induced cognitive impairment by modulating microglia polarization, neuroinflammation, and synaptic plasticity, at least partly via activation of PI3K/AKT signaling in the hippocampus. LXRs may be promising targets for addressing pain-related cognitive deficits.

Transcriptional characterization of iPSC-derived microglia as a model for therapeutic development in neurodegeneration

Microglia are the resident immune cells in the brain that play a key role in driving neuroinflammation, a hallmark of neurodegenerative disorders. Inducible microglia-like cells have been developed as an in vitro platform for molecular and therapeutic hypothesis generation and testing. However, there has been no systematic assessment of similarity of these cells to primary human microglia along with their responsiveness to external cues expected of primary cells in the brain. In this study, we performed transcriptional characterization of commercially available human inducible pluripotent stem cell (iPSC)-derived microglia-like (iMGL) cells by bulk and single cell RNA sequencing to assess their similarity with primary human microglia. To evaluate their stimulation responsiveness, iMGL cells were treated with Liver X Receptor (LXR) pathway agonists and their transcriptional responses characterized by bulk and single cell RNA sequencing. Bulk transcriptome analyses demonstrate that iMGL cells have a similar overall expression profile to freshly isolated human primary microglia and express many key microglial transcription factors and functional and disease-associated genes. Notably, at the single-cell level, iMGL cells exhibit distinct transcriptional subpopulations, representing both homeostatic and activated states present in normal and diseased primary microglia. Treatment of iMGL cells with LXR pathway agonists induces robust transcriptional changes in lipid metabolism and cell cycle at the bulk level. At the single cell level, we observe heterogeneity in responses between cell subpopulations in homeostatic and activated states and deconvolute bulk expression changes into their corresponding single cell states. In summary, our results demonstrate that iMGL cells exhibit a complex transcriptional profile and responsiveness, reminiscent of in vivo microglia, and thus represent a promising model system for therapeutic development in neurodegeneration.

Cholesterol biosynthetic pathway induces cellular senescence through ERRα

Cellular senescence is a cell program induced by various stresses that leads to a stable proliferation arrest and to a senescence-associated secretory phenotype. Accumulation of senescent cells during age-related diseases participates in these pathologies and regulates healthy lifespan. Recent evidences point out a global dysregulated intracellular metabolism associated to senescence phenotype. Nonetheless, the functional contribution of metabolic homeostasis in regulating senescence is barely understood. In this work, we describe how the mevalonate pathway, an anabolic pathway leading to the endogenous biosynthesis of poly-isoprenoids, such as cholesterol, acts as a positive regulator of cellular senescence in normal human cells. Mechanistically, this mevalonate pathway-induced senescence is partly mediated by the downstream cholesterol biosynthetic pathway. This pathway promotes the transcriptional activity of ERRα that could lead to dysfunctional mitochondria, ROS production, DNA damage and a p53-dependent senescence. Supporting the relevance of these observations, increase of senescence in liver due to a high-fat diet regimen is abrogated in ERRα knockout mouse. Overall, this work unravels the role of cholesterol biosynthesis or level in the induction of an ERRα-dependent mitochondrial program leading to cellular senescence and related pathological alterations.

A new perspective on the current and future development potential of ABCG1

ABCG1 is an essential protein involved in the efflux of intracellular cholesterol to the extracellular space, thus playing a critical role in reducing cholesterol accumulation in neighboring tissues. Bibliometric analysis pertains to the interdisciplinary field of quantitative examination of diverse documents using mathematical and statistical techniques. It integrates the investigation of structural and temporal patterns in academic publications with an exploration of subject focus and forms of uncertainty. This research paper examines the historical evolution, current areas of interest, and future development trends of ABCG1 through bibliometric analysis. This study aims to offer readers insights into the research status and emerging trends of ABCG1, thereby assisting researchers in the exciting field to explore novel research avenues. Following rigorous selection, research on ABCG1 has remained highly active over the past two decades. ABCG1 has even started to emerge in previously unrelated fields, such as the field of cancer research. According to the analysis conducted by Citespace, a lot of keywords and influential citations were identified. ABCG1 has been found to establish a connection between cancer and cardiovascular disease, highlighting their interrelationship. This review aims to assist readers who have limited familiarity with ABCG1 research in gaining a rapid understanding of its developmental trajectory. Additionally, it aims to offer researchers potential areas of focus for future studies related to ABCG1.

The GR-KLF15 axis promotes suppression of hepatic lipogenesis during fasting

Fasting leads to many physiological changes in peripheral tissues, including the liver, where suppression of de novo lipogenesis through inhibition of sterol regulatory element-binding protein 1 (SREBP-1) expression and/or activity is a key adaptation to preserve glucose for maintenance of blood glucose levels. Yoshinori Takeuchi and colleagues provide novel mechanistic insights into the regulation of SREBP-1 expression during fasting and highlight the importance of the hypothalamic-pituitary-adrenal axis and, particularly, glucocorticoid-induced binding of the glucocorticoid receptor to enhancer regions of the KLF15 (Kruppel-like factor 15) gene as a novel mechanism underlying the suppression of SREBP-1 during fasting.

The Antiobesity Effects and Potential Mechanisms of Theaflavins

Theaflavins are the characteristic polyphenols in black tea which can be enzymatically synthesized. In this review, the effects and molecular mechanisms of theaflavins on obesity and its comorbidities, including dyslipidemia, insulin resistance, hepatic steatosis, and atherosclerosis, were summarized. Theaflavins ameliorate obesity potentially via reducing food intake, inhibiting pancreatic lipase to reduce lipid absorption, activating the adenosine monophosphate-activated protein kinase (AMPK), and regulating the gut microbiota. As to the comorbidities, theaflavins ameliorate hypercholesterolemia by inhibiting micelle formation to reduce cholesterol absorption. Theaflavins improve insulin sensitivity by increasing the signaling of protein kinase B, eliminating glucose toxicity, and inhibiting inflammation. Theaflavins ameliorate hepatic steatosis via activating AMPK. Theaflavins reduce atherosclerosis by upregulating nuclear factor erythropoietin-2-related factor 2 signaling and inhibiting plasminogen activator inhibitor 1. In randomized controlled trails, black tea extracts containing theaflavins reduced body weight in overweight people and improved glucose tolerance in healthy adults. The amelioration on the hyperlipidemia and the prevention of coronary artery disease by black tea extracts were supported by meta-analysis.

The roles of nuclear receptors in cholesterol metabolism and reverse cholesterol transport in nonalcoholic fatty liver disease

As the most prevalent chronic liver disease globally, NAFLD encompasses a pathological process that ranges from simple steatosis to NASH, fibrosis, cirrhosis, and HCC, closely associated with numerous extrahepatic diseases. While the initial etiology was believed to be hepatocyte injury caused by lipid toxicity from accumulated triglycerides, recent studies suggest that an imbalance of cholesterol homeostasis is of greater significance. The role of nuclear receptors in regulating liver cholesterol homeostasis has been demonstrated to be crucial. This review summarizes the roles and regulatory mechanisms of nuclear receptors in the 3 main aspects of cholesterol production, excretion, and storage in the liver, as well as their cross talk in reverse cholesterol transport. It is hoped that this review will offer new insights and theoretical foundations for the study of the pathogenesis and progression of NAFLD and provide new research directions for extrahepatic diseases associated with NAFLD.

Neutrophil-like pH-responsive pro-efferocytic nanoparticles improve neurological recovery by promoting erythrophagocytosis after intracerebral hemorrhage

Rationale: Intracerebral hemorrhage (ICH) is a devastating cerebrovascular disease resulting from blood extravasating into the brain parenchyma. Escalation of erythrophagocytosis (a form of efferocytosis), avoiding the consequent release of the detrimental erythrocyte lysates, may be a promising target of ICH management. The ADAM17 inhibitor and liver X receptor (LXR) agonist could promote efficient efferocytosis and injury repair. Nevertheless, the poor bioavailability and restriction of the blood-brain barrier (BBB) hinder their application. Therefore, it is needed that biocompatible and smart nanoplatforms were designed and synthesized to realize effective therapy targeting erythrophagocytosis. Methods: We first assessed the synergistic effect of therapeutic GW280264X (an ADAM17 inhibitor) and desmosterol (an LXR agonist) on erythrophagocytosis in vitro. Then a pH-responsive neutrophil membrane-based nanoplatform (NPEOz) served as a carrier to accurately deliver therapeutic GW280264X and desmosterol to the damaged brain was prepared via co-extrusion. Afterwards, their pH-responsive performance was valued in vitro and targeting ability was assessed through fluorescence image in vivo. Finally, the pro-erythrophagocytic and anti-neuroinflammatory ability of the nanomedicine and related mechanisms were investigated. Results: After the synergistical effect of the above two drugs on erythrophagocytosis was confirmed, we successfully developed neutrophil-disguised pH-responsive nanoparticles to efficiently co-deliver them. The nanoparticles could responsively release therapeutic agents under acidic environments, and elicit favorable biocompatibility and ability of targeting injury sites. D&G@NPEOz nanoparticles enhanced erythrophagocytosis through inhibiting shedding of the efferocytotic receptors MERTK/AXL mediated by ADAM17 and accelerating ABCA-1/ABCG-1-mediated cholesterol efflux regulated by LXR respectively. In addition, the nano-formulation was able to modulate the inflammatory microenvironment by transforming efferocytes towards a therapeutic phenotype with reducing the release of proinflammatory cytokines while increasing the secretion of anti-inflammatory factors, and improve neurological function. Conclusions: This biomimetic nanomedicine is envisaged to offer an encouraging strategy to effectively promote hematoma and inflammation resolution, consequently alleviate ICH progression.

The Role of Nuclear Receptors in the Pathogenesis and Treatment of Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a global health burden closely linked to insulin resistance, obesity, and type 2 diabetes. The complex pathophysiology of NAFLD involves multiple cellular pathways and molecular factors. Nuclear receptors (NRs) have emerged as crucial regulators of lipid metabolism and inflammation in NAFLD, offering potential therapeutic targets for NAFLD. Targeting PPARs and FXRs has shown promise in ameliorating NAFLD symptoms and halting disease progression. However, further investigation is needed to address side effects and personalize therapy approaches. This review summarizes the current understanding of the involvement of NRs in the pathogenesis of NAFLD and explores their therapeutic potential. We discuss the role of several NRs in modulating lipid homeostasis in the liver, including peroxisome proliferator-activated receptors (PPARs), liver X receptors (LXRs), farnesoid X receptors (FXRs), REV-ERB, hepatocyte nuclear factor 4α (HNF4α), constitutive androstane receptor (CAR) and pregnane X receptor (PXR).The expanding knowledge of NRs in NAFLD offers new avenues for targeted therapies, necessitating exploration of novel treatment strategies and optimization of existing approaches to combat this increasingly prevalent disease.

Essential oil from Fructus Alpinia zerumbet ameliorates atherosclerosis by activating PPARγ-LXRα-ABCA1/G1 signaling pathway

BACKGROUND

Atherosclerosis (AS) is a progressive chronic disease. Currently, cardiovascular diseases (CVDs) caused by AS is responsible for the global increased mortality. Yanshanjiang as miao herb in Guizhou of China is the dried and ripe fruit of Fructus Alpinia zerumbet. Accumulated evidences have confirmed that Yanshanjiang could ameliorate CVDs, including AS. Nevertheless, its effect and mechanism on AS are still largely unknown.

PURPOSE

To investigate the role of essential oil from Fructus Alpinia zerumbet (EOFAZ) on AS, and the potential mechanism.

METHODS

A high-fat diet (HFD) ApoE-/- mice model of AS and a oxLDL-induced model of macrophage-derived foam cells (MFCs) were reproduced to investigate the pharmacological properties of EOFAZ on AS in vivo and foam cell formation in vitro, respectively. The underlying mechanisms of EOFAZ were investigated using Network pharmacology and molecular docking. EOFAZ effect on PPARγ protein stability was measured using a cellular thermal shift assay (CETSA). Pharmacological agonists and inhibitors and gene interventions were employed for clarifying EOFAZ's potential mechanism.

RESULTS

EOFAZ attenuated AS progression in HFD ApoE-/- mice. This attenuation was manifested by the reduced aortic intima plaque development, increased collagen content in aortic plaques, notable improvement in lipid profiles, and decreased levels of inflammatory factors. Moreover, EOFAZ inhibited the formation of MFCs by enhancing cholesterol efflux through activiting the PPARγ-LXRα-ABCA1/G1 pathway. Interestingly, the pharmacological knockdown of PPARγ impaired the beneficial effects of EOFAZ on MFCs. Additionally, our results indicated that EOFAZ reduced the ubiquitination degradation of PPARγ, and the chemical composition of EOFAZ directly bound to the PPARγ protein, thereby increasing its stability. Finally, PPARγ knockdown mitigated the protective effects of EOFAZ on AS in HFD ApoE-/- mice.

CONCLUSION

These findings represent the first confirmation of EOFAZ's in vivo anti-atherosclerotic effects in ApoE-/- mice. Mechanistically, its chemical constituents can directly bind to PPARγ protein, enhancing its stability, while reducing PPARγ ubiquitination degradation, thereby inhibiting foam cell formation via activation of the PPARγ-LXRα-ABCA1/G1 pathway. Simultaneously, EOFAZ could ameliorates blood lipid metabolism and inflammatory microenvironment, thus synergistically exerting its anti-atherosclerotic effects.

Enzymatically Formed Oxysterols and Cell Death

The side-chain hydroxylation of cholesterol by specific enzymes produces 24(S)-hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol, and other products. These enzymatically formed side-chain oxysterols act as intermediates in the biosynthesis of bile acids and serve as signaling molecules that regulate cholesterol homeostasis. Besides these intracellular functions, an imbalance in oxysterol homeostasis is implicated in pathophysiology. Furthermore, growing evidence reveals that oxysterols affect cell proliferation and cause cell death. This chapter provides an overview of the pathophysiological role of side-chain oxysterols in developing human diseases. We also summarize our understanding of the molecular mechanisms underlying the induction of various forms of cell death by side-chain oxysterols.

Ginsenoside F2 Restrains Hepatic Steatosis and Inflammation by Altering the Binding Affinity of Liver X Receptor Coregulators

Background

Ginsenoside F2 (GF2), the protopanaxadiol-type constituent in Panax ginseng, has been reported to attenuate metabolic dysfunction-associated steatotic liver disease (MASLD). However, the mechanism of action is not fully understood. Here, this study investigates the molecular mechanism by which GF2 regulates MASLD progression through liver X receptor (LXR).

Methods

To demonstrate the effect of GF2 on LXR activity, computational modeling of protein-ligand binding, Time-resolved fluorescence resonance energy transfer (TR-FRET) assay for LXR cofactor recruitment, and luciferase reporter assay were performed. LXR agonist T0901317 was used for LXR activation in hepatocytes and macrophages. MASLD was induced by high-fat diet (HFD) feeding with or without GF2 administration in WT and LXRα-/- mice.

Results

Computational modeling showed that GF2 had a high affinity with LXRα. LXRE-luciferase reporter assay with amino acid substitution at the predicted ligand binding site revealed that the S264 residue of LXRα was the crucial interaction site of GF2. TR-FRET assay demonstrated that GF2 suppressed LXRα activity by favoring the binding of corepressors to LXRα while inhibiting the accessibility of coactivators. In vitro, GF2 treatments reduced T0901317-induced fat accumulation and pro-inflammatory cytokine expression in hepatocytes and macrophages, respectively. Consistently, GF2 administration ameliorated hepatic steatohepatitis and improved glucose or insulin tolerance in WT but not in LXRα-/- mice.

Conclusion

GF2 alters the binding affinities of LXRα coregulators, thereby interrupting hepatic steatosis and inflammation in macrophages. Therefore, we propose that GF2 might be a potential therapeutic agent for the intervention in patients with MASLD.

Enhanced liver X receptor signalling reduces brain injury and promotes tissue regeneration following experimental intracerebral haemorrhage: roles of microglia/macrophages

BACKGROUND

Inflammation-exacerbated secondary brain injury and limited tissue regeneration are barriers to favourable prognosis after intracerebral haemorrhage (ICH). As a regulator of inflammation and lipid metabolism, Liver X receptor (LXR) has the potential to alter microglia/macrophage (M/M) phenotype, and assist tissue repair by promoting cholesterol efflux and recycling from phagocytes. To support potential clinical translation, the benefits of enhanced LXR signalling are examined in experimental ICH.

METHODS

Collagenase-induced ICH mice were treated with the LXR agonist GW3965 or vehicle. Behavioural tests were conducted at multiple time points. Lesion and haematoma volume, and other brain parameters were assessed using multimodal MRI with T2-weighted, diffusion tensor imaging and dynamic contrast-enhanced MRI sequences. The fixed brain cryosections were stained and confocal microscopy was applied to detect LXR downstream genes, M/M phenotype, lipid/cholesterol-laden phagocytes, oligodendrocyte lineage cells and neural stem cells. Western blot and real-time qPCR were also used. CX3CR1CreER: Rosa26iDTR mice were employed for M/M-depletion experiments.

RESULTS

GW3965 treatment reduced lesion volume and white matter injury, and promoted haematoma clearance. Treated mice upregulated LXR downstream genes including ABCA1 and Apolipoprotein E, and had reduced density of M/M that apparently shifted from proinflammatory interleukin-1β+ to Arginase1+CD206+ regulatory phenotype. Fewer cholesterol crystal or myelin debris-laden phagocytes were observed in GW3965 mice. LXR activation increased the number of Olig2+PDGFRα+ precursors and Olig2+CC1+ mature oligodendrocytes in perihaematomal regions, and elevated SOX2+ or nestin+ neural stem cells in lesion and subventricular zone. MRI results supported better lesion recovery by GW3965, and this was corroborated by return to pre-ICH values of functional rotarod activity. The therapeutic effects of GW3965 were abrogated by M/M depletion in CX3CR1CreER: Rosa26iDTR mice.

CONCLUSIONS

LXR agonism using GW3965 reduced brain injury, promoted beneficial properties of M/M and facilitated tissue repair correspondent with enhanced cholesterol recycling.

Enhancing Immunotherapy in Ovarian Cancer: The Emerging Role of Metformin and Statins

Ovarian cancer metastization is accompanied by the development of malignant ascites, which are associated with poor prognosis. The acellular fraction of this ascitic fluid contains tumor-promoting soluble factors, bioactive lipids, cytokines, and extracellular vesicles, all of which communicate with the tumor cells within this peritoneal fluid. Metabolomic profiling of ovarian cancer ascites has revealed significant differences in the pathways of fatty acids, cholesterol, glucose, and insulin. The proteins involved in these pathways promote tumor growth, resistance to chemotherapy, and immune evasion. Unveiling the key role of this liquid tumor microenvironment is crucial for discovering more efficient treatment options. This review focuses on the cholesterol and insulin pathways in ovarian cancer, identifying statins and metformin as viable treatment options when combined with standard chemotherapy. These findings are supported by clinical trials showing improved overall survival with these combinations. Additionally, statins and metformin are associated with the reversal of T-cell exhaustion, positioning these drugs as potential combinatory strategies to improve immunotherapy outcomes in ovarian cancer patients.

TRIM21-mediated Sohlh2 ubiquitination suppresses M2 macrophage polarization and progression of triple-negative breast cancer

Lung metastasis is the major cause of death in patients with triple-negative breast cancer (TNBC). Tumor-associated macrophages (TAMs) represent the M2-like phenotype with potent immunosuppressive activity, and play a pro-tumor role in TNBC lung metastasis. Sohlh2 belongs to the basic helix-loop-helix transcription factor family. However, its role in macrophages polarization remains unknown, especially in TNBC progression. Here we demonstrated that Sohlh2 overexpression promoted M2 macrophage polarization. Moreover, high expression of Sohlh2 in M2-like macrophage enhanced TNBC cell growth, migration and lung metastasis in vivo and in vitro. Mechanistically, we revealed that Sohlh2 functioned through up-regulating LXRα, ABCA1, ABCG1 expression and disturbing the lipid homeostasis on the membrane of macrophages. Sohlh2 could directly bind to the promoter of LXRα and promote its transcription activity. E3 ubiquitin ligase TRIM21 promoted Sohlh2 ubiquitination and degradation, and suppressed M2 macrophage polarization and TNBC progression. Collectively, our findings suggested that Sohlh2 in macrophage could be a novel therapeutic target for TNBC metastatic treatment.

Hepatic Huwe1 loss protects mice from non-alcoholic fatty liver disease through lipid metabolic rewiring

Non-alcoholic fatty liver disease (NAFLD) is the most pervasive liver pathology worldwide. Here, we demonstrate that the ubiquitin E3 ligase Huwe1 is vital in NAFLD pathogenesis. Using mass spectrometry and RNA sequencing, we reveal that liver-specific deletion of Huwe1 (Huwe1LKO) in 1-year-old mice (approximately middle age in humans) elicits extensive lipid metabolic reprogramming that involves downregulation of de novo lipogenesis and fatty acid uptake, upregulation of fatty acid β-oxidation, and increased oxidative phosphorylation. ChEA transcription factor prediction analysis inferred these changes result from attenuated PPARɑ, LXR, and RXR activity in Huwe1LKO livers. Consequently, Huwe1LKO mice fed chow diet exhibited significantly reduced hepatic steatosis and superior glucose tolerance compared to wild-type mice. Huwe1LKO also conferred protection from high-fat diet-induced hepatic steatosis by 6-months of age, with increasingly robust differences observed as mice reached middle age. Together, we present evidence that Huwe1 plays a critical role in the development of age- and diet-induced NAFLD.

Atherosclerotic plaque development in mice is enhanced by myeloid ZEB1 downregulation

Accumulation of lipid-laden macrophages within the arterial neointima is a critical step in atherosclerotic plaque formation. Here, we show that reduced levels of the cellular plasticity factor ZEB1 in macrophages increase atherosclerotic plaque formation and the chance of cardiovascular events. Compared to control counterparts (Zeb1WT/ApoeKO), male mice with Zeb1 ablation in their myeloid cells (Zeb1∆M/ApoeKO) have larger atherosclerotic plaques and higher lipid accumulation in their macrophages due to delayed lipid traffic and deficient cholesterol efflux. Zeb1∆M/ApoeKO mice display more pronounced systemic metabolic alterations than Zeb1WT/ApoeKO mice, with higher serum levels of low-density lipoproteins and inflammatory cytokines and larger ectopic fat deposits. Higher lipid accumulation in Zeb1∆M macrophages is reverted by the exogenous expression of Zeb1 through macrophage-targeted nanoparticles. In vivo administration of these nanoparticles reduces atherosclerotic plaque formation in Zeb1∆M/ApoeKO mice. Finally, low ZEB1 expression in human endarterectomies is associated with plaque rupture and cardiovascular events. These results set ZEB1 in macrophages as a potential target in the treatment of atherosclerosis.

Danlou Recipe promotes cholesterol efflux in macrophages RAW264.7 and reverses cholesterol transport in mice with hyperlipidemia induced by P407

INTRODUCTION

Liver X Receptor (LXR) agonists could attenuate the development of atherosclerosis but bring excess lipid accumulation in the liver. Danlou Recipe was believed to be a benefit for improving the lipid profile. Thus, it is unclear whether Danlou Recipe could attenuate hyperlipidemia without excess lipid accumulated in the liver of mice. This study aimed to clarify if Danlou Recipe could alleviate the progression of hyperlipidemia in mice without extra lipids accumulated in the liver.

METHODS

Male murine macrophage RAW264.7 cells and murine peritoneal macrophages were used for the in vitro experiments. Cellular cholesterol efflux was determined using the fluorescent cholesterol labeling method. Those genes involved in lipid metabolism were evaluated by qRT-PCR and western blotting respectively. In vivo, a mouse model of hyperlipidemia induced by P407 was used to figure out the effect of Danlou Recipe on reverse cholesterol transport (RCT) and hyperlipidemia. Ethanol extract of Danlou tablet (EEDL) was prepared by extracting the whole powder of Danlou Prescription from ethanol, and the chemical composition was analyzed by ultra-performance liquid chromatography (UPLC).

RESULTS

EEDL inhibits the formation of RAW264.7 macrophage-derived foam cells, and promotes ABCA1/apoA1 conducted cholesterol efflux in RAW264.7 macrophages and mouse peritoneal macrophages. In the P407-induced hyperlipidemia mouse model, oral administration of EEDL can promote RCT in vivo and improve fatty liver induced by a high-fat diet. Consistent with the findings in vitro, EEDL promotes RCT by upregulating the LXR activities.

CONCLUSION

Our results demonstrate that EEDL has the potential for targeting RCT/LXR in the treatment of lipid metabolism disorders to be developed as a safe and effective therapy.

Ligand flexibility and binding pocket malleability cooperate to allow selective PXR activation by analogs of a promiscuous nuclear receptor ligand

The human nuclear receptor (NR) family of transcription factors contains 48 proteins that bind lipophilic molecules. Approved NR therapies have had immense success treating various diseases, but lack of selectivity has hindered efforts to therapeutically target the majority of NRs due to unpredictable off-target effects. The synthetic ligand T0901317 was originally discovered as a potent agonist of liver X receptors (LXRα/β) but subsequently found to target additional NRs, with activation of pregnane X receptor (PXR) being as potent as that of LXRs. We previously showed that directed rigidity reduces PXR binding by T0901317 derivatives through unfavorable protein remodeling. Here, we use a similar approach to achieve selectivity for PXR over other T0901317-targeted NRs. One molecule, SJPYT-318, accomplishes selectivity by favorably utilizing PXR's flexible binding pocket and surprisingly binding in a new mode distinct from the parental T0901317. Our work provides a structure-guided framework to achieve NR selectivity from promiscuous compounds.

The combined characteristics of cholesterol metabolism and the immune microenvironment may serve as valuable biomarkers for both the prognosis and treatment of hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) being a complex disease, commonly exhibits multifaceted presentations, rendering its treatment challenging and necessitating specific approaches. The tumor immune microenvironment is crucial in cancer treatment, and cholesterol metabolism is a key component that helps cells grow and produce vital metabolites. However, the reprogramming of cholesterol metabolism in the tumor microenvironment (TME) can promote HCC development, and cancer classifiers relating to cholesterol metabolism are currently limited. Despite significant progress, further research is needed to improve early detection, liver function, and treatment options to improve patient outcomes.

Methods

To evaluate the expression abundance of tumor immune microenvironment (TIME) and cholesterol metabolism in 8 types of liver cancer cells, we comprehensively evaluated the immune cell composition, extracellular matrix alterations, and activity of relevant signaling pathways in the TIME through nine liver cancer patients, stromal scoring, immune scoring, tumor purity scoring, immune infiltration analysis, and pathway enrichment. Subsequently, we utilized machine learning techniques to construct prognostic models for both cholesterol metabolism and the tumor immune microenvironment, further exploring the tumor mutation burden, immune infiltration levels, and drug sensitivity in different subtypes of HCC patients.

Results

Our study constructed three cancer screening models to identify HCC patients with high cholesterol metabolism and low TIME, who have a poorer prognosis. On the contrary, patients with low cholesterol metabolism and high TIME often have better prognosis. Furthermore, we identified chemical compounds, such as BPD-00008900, ML323, Doramapimod, and AZD2014, which display better chemotherapy results for high-risk patients in specific sub-groups.

Nrf1 is not a direct target gene of SREBP1, albeit both are integrated into the rapamycin-responsive regulatory network in human hepatoma cells

The essential role of protein degradation by ubiquitin-proteasome system is exerted primarily for maintaining cellular protein homeostasis. The transcriptional activation of proteasomal genes by mTORC1 signaling depends on Nrf1, but whether this process is directly via SREBP1 remains elusive. In this study, our experiment evidence revealed that Nrf1 is not a direct target of SREBP1, although both are involved in the rapamycin-responsive regulatory networks. Closely scrutinizing two distinct transcriptomic datasets unraveled no significant changes in transcriptional expression of Nrf1 and almost all proteasomal subunits in either siSREBP2-silencing cells or SREBP1-∕-MEFs, when compared to equivalent controls. However, distinct upstream signaling to Nrf1 dislocation by p97 and its processing by DDI1/2, along with downstream proteasomal expression, may be monitored by mTOR signaling, to various certain extents, depending on distinct experimental settings in different types of cells. Our further evidence has been obtained from DDI1-∕-(DDI2insC) cells, demonstrating that putative effects of mTOR on the rapamycin-responsive signaling to Nrf1 and proteasomes may also be executed partially through a DDI1/2-independent mechanism, albeit the detailed regulatory events remain to be determined.

Dietary Phenolic Compounds Exert Some of Their Health-Promoting Bioactivities by Targeting Liver X Receptor (LXR) and Retinoid X Receptor (RXR)

Consuming foods of vegetable origin has been shown to exert multiple health-related effects, many of them attributed to their phenolic compounds. These molecules are known for being bioactive across multiple cells and organs, with documented changes in gene expression being commonly reported. Nuclear receptors are signal transducers capable of regulating gene expression in response to endogenous and/or exogenous ligands. Liver X receptor (LXR) and retinoid X receptor (RXR) are two important nuclear receptors that can be acted on by phenolic compounds, thereby modifying gene expression and potentially exerting numerous subsequent bioactivities. The present work summarizes recent evidence of the effects of the phenolic compounds that are exerted by targeting LXR and/or RXR. The data show that, when LXR is being targeted, changes in lipid metabolism are commonly observed, due to its ability to regulate genes relevant to this process. The effects vary widely when RXR is the target since it is involved in processes like cell proliferation, vitamin D metabolism, and multiple others by forming heterodimers with other transcription factors that regulate said processes. The evidence therefore shows that phenolic compounds can exert multiple bioactivities, with a mechanism of action based, at least in part, on their ability to modulate the cell at the molecular level by acting on nuclear receptors. The data point to a promising and novel area of study that links diet and health, although various unknowns justify further experimentation to reveal the precise way in which a given phenolic can interact with a nuclear receptor.