SREBPs in Lipid Metabolism, Insulin Signaling, and Beyond

Interactions of Fatty Acid and Cholesterol Metabolism with Cellular Stress Response Pathways in Cancer

Lipids have essential functions as structural components of cellular membranes, as efficient energy storage molecules, and as precursors of signaling mediators. While deregulated glucose and amino acid metabolism in cancer have received substantial attention, the roles of lipids in the metabolic reprogramming of cancer cells are less well understood. However, since the first description of de novo fatty acid biosynthesis in cancer tissues almost 70 years ago, numerous studies have investigated the complex functions of altered lipid metabolism in cancer. Here, we will summarize the mechanisms by which oncogenic signaling pathways regulate fatty acid and cholesterol metabolism to drive rapid proliferation and protect cancer cells from environmental stress. The review also discusses the role of fatty acid metabolism in metabolic plasticity required for the adaptation to changing microenvironments during cancer progression and the connections between fatty acid and cholesterol metabolism and ferroptosis.

A scoping review and hypothetical framework about the interplay between oxytocin and eating disorders

INTRODUCTION

Despite emerging evidence on oxytocin's role in eating disorders,there is a need for a comprehensive review to integrate findings across neurobiological, genetic, hormonal, and therapeutic dimensions. This scoping review synthesizes existing literature on OXT's role in EDs and proposes a new theoretical perspective based on diverse research findings.

METHODS

In accordance with PRISMA guidelines, we systematically synthesized all peer-reviewed articles indexed on PubMed which focused on both OXT and EDs as of December 2023 (k = 32 studies, n = 1942 participants). After summarizing this literature in tables, we completed the narrative synthesis with a discussion of mechanisms informed by an unstructured literature review.

RESULTS

The existing studies propose a connection between OXT receptor Oxtr polymorphisms and ED diagnoses, severity of symptoms, macronutrient preferences, reward function, and early life stress. In addition, OXT plasma levels normalized with ED symptom reduction. Although some OXT studies have failed to show therapeutic changes in food intake and weight, few have reported ameliorations in brain function, food-related attentional bias, cognition, and emotional regulation. Some data have also suggested a contributory role of the transforming growth factor β (TGFβ) and sterol regulatory element binding proteins (SREBPs) to the etiology of EDs through Oxtr expression.

CONCLUSION

Although the current evidence does not support OXT as a standalone cause of or treatment for EDs, OXT research holds promise as a way of identifying future therapies, and OXT itself may serve as a valuable adjunct.

Cholesterol metabolism in pancreatic cancer and associated therapeutic strategies

Pancreatic cancer remains one of the most lethal cancers due to late diagnosis and high chemoresistance. Despite recent progression in the development of chemotherapies, immunotherapies, and potential nanoparticles-based approaches, the success rate of therapeutic response is limited which is further compounded by cancer drug resistance. Understanding of emerging biological and molecular pathways causative of pancreatic cancer's aggressive and chemoresistance is vital to improve the effectiveness of existing therapeutics and to develop new therapies. One such under-investigated and relatively less explored area of research is documenting the effect that lipids, specifically cholesterol, and its metabolism, impose on pancreatic cancer. Dysregulated cholesterol metabolism has a profound role in supporting cellular proliferation, survival, and promoting chemoresistance and this has been well established in various other cancers. Thus, we aimed to provide an in-depth review focusing on the significance of cholesterol metabolism in pancreatic cancer and relevant genes at play, molecular processes contributing to cellular cholesterol homeostasis, and current research efforts to develop new cholesterol-targeting therapeutics. We highlight the caveats, weigh in different experimental therapeutic strategies, and provide possible suggestions for future research highlighting cholesterol's importance as a therapeutic target against pancreatic cancer resistance and cancer progression.

Attenuated growth factor signaling during cell death initiation sensitizes membranes towards peroxidation

Cell death programs such as apoptosis and ferroptosis are associated with aberrant redox homeostasis linked to lipid metabolism and membrane function. Evidence for cross-talk between these programs is emerging. Here, we show that cytotoxic stress channels polyunsaturated fatty acids via lysophospholipid acyltransferase 12 into phospholipids that become susceptible to peroxidation under additional redox stress. This reprogramming is associated with altered acyl-CoA synthetase isoenzyme expression and caused by a decrease in growth factor receptor tyrosine kinase (RTK)-phosphatidylinositol-3-kinase signaling, resulting in suppressed fatty acid biosynthesis, for specific stressors via impaired Akt-SREBP1 activation. The reduced availability of de novo synthesized fatty acids favors the channeling of polyunsaturated fatty acids into phospholipids. Growth factor withdrawal by serum starvation mimics this phenotype, whereas RTK ligands counteract it. We conclude that attenuated RTK signaling during cell death initiation increases cells' susceptibility to oxidative membrane damage at the interface of apoptosis and alternative cell death programs.

SREBF1-based metabolic reprogramming in prostate cancer promotes tumor ferroptosis resistance

Metabolic reprogramming in prostate cancer has been widely recognized as a promoter of tumor progression and treatment resistance. This study investigated its association with ferroptosis resistance in prostate cancer and explored its therapeutic potential. In this study, we identified differences in the epithelial characteristics between normal prostate tissue and tissues of various types of prostate cancer using single-cell sequencing. Through transcription factor regulatory network analysis, we focused on the candidate transcription factor, SREBF1. We identified the differences in SREBF1 transcriptional activity and its association with ferroptosis, and further verified this association using hdWGCNA. We constructed a risk score based on SREBF1 target genes associated with the biochemical recurrence of prostate cancer by combining bulk RNA analysis. Finally, we verified the effects of the SREBPs inhibitor Betulin on the treatment of prostate cancer and its chemosensitization effect. We observed characteristic differences in fatty acid and cholesterol metabolism between normal prostate tissue and prostate cancer tissue, identifying high transcriptional activity of SREBF1 in prostate cancer tissue. This indicates that SREBF1 is crucial for the metabolic reprogramming of prostate cancer, and that its mediated metabolic changes promoted ferroptosis resistance in prostate cancer in multiple ways. SREBF1 target genes are associated with biochemical recurrence of prostate cancer. Finally, our experiments verified that SREBF1 inhibitors can significantly promote an increase in ROS, the decrease in GSH, and the decrease in mitochondrial membrane potential in prostate cancer cells and confirmed their chemosensitization effect in vivo. Our findings highlighted a close association between SREBF1 and ferroptosis resistance in prostate cancer. SREBF1 significantly influences metabolic reprogramming in prostate cancer cells, leading to ferroptosis resistance. Importantly, our results demonstrated that SREBF1 inhibitors can significantly enhance the therapeutic effect and chemosensitization of prostate cancer, suggesting a promising therapeutic potential for the treatment of prostate cancer.

Metabolic Regulation by p53: Implications for Cancer Therapy

The tumor suppressor p53, long known for its roles in maintaining genomic integrity and suppressing tumorigenesis, has recently been recognized as a key regulator of cellular metabolism. Here, we review p53's emerging metabolic functions, highlighting its ability to orchestrate glucose, amino acid, and lipid metabolism. By promoting oxidative phosphorylation while inhibiting glycolysis and anabolic pathways, wild-type p53 counters metabolic reprogramming characteristic of cancer cells, such as the Warburg effect, and protects cells from mild cellular stresses. In contrast, mutant p53 disrupts these processes, fostering metabolic adaptations that support tumor progression. These findings pave the way for therapeutic approaches targeting p53-driven metabolic vulnerabilities in cancer.

Molecular Characteristics and Role of Buffalo SREBF2 in Triglyceride and Cholesterol Biosynthesis in Mammary Epithelial Cells

Background/Objectives: Sterol regulatory element-binding transcription factor 2 (SREBF2) is a key transcription factor involved in regulating cholesterol homeostasis. However, its role in buffalo mammary gland lipid metabolism remains unclear. Methods: To address this, we isolated and characterized the SREBF2 gene from buffalo mammary glands and performed an in-depth analysis of its molecular characteristics, tissue-specific expression, and functional roles in buffalo mammary epithelial cells (BuMECs). Additionally, we investigated the single nucleotide polymorphisms (SNPs) of SREBF2 in both river and swamp buffalo. Results: The coding sequence (CDS) of buffalo SREBF2 is 3327 bp long and encodes a protein of 1108 amino acid residues. Bioinformatics analysis revealed that the molecular characteristics of buffalo SREBF2 were highly similar across Bovidae species, with collinearity being observed among them. An expression profile analysis revealed that SREBF2 is expressed in all 11 tested tissues of buffalo, with its expression level in the mammary gland being higher during lactation than in the dry period. The knockdown of SREBF2 in BuMECs during lactation led to a significant reduction in the expression of genes involved in triglyceride (TAG) and cholesterol synthesis, including PI3K, AKT, mTOR, SREBF1, PPARG, INSIG1, ACACA, SCD, DGAT1, LPL, CD36, HMGCR, and SQLE. This knockdown led to a 23.53% and 94.56% reduction in TAG and cholesterol levels in BuMECs, respectively. In addition, a total of 22 SNPs were identified in both buffalo types, of which four non-synonymous substitutions (c.301G>C, c.304A>T, c.1240G>A, and c.2944G>A) were found exclusively in the SREBF2 CDS of swamp buffalo, and the assessment revealed that these substitutions had no impact on SREBF2 function. Conclusions: These findings emphasize the critical role of SREBF2 in regulating both triglyceride and cholesterol biosynthesis, providing valuable insights into its functions in buffalo mammary glands.

Energy metabolism in health and diseases

Energy metabolism is indispensable for sustaining physiological functions in living organisms and assumes a pivotal role across physiological and pathological conditions. This review provides an extensive overview of advancements in energy metabolism research, elucidating critical pathways such as glycolysis, oxidative phosphorylation, fatty acid metabolism, and amino acid metabolism, along with their intricate regulatory mechanisms. The homeostatic balance of these processes is crucial; however, in pathological states such as neurodegenerative diseases, autoimmune disorders, and cancer, extensive metabolic reprogramming occurs, resulting in impaired glucose metabolism and mitochondrial dysfunction, which accelerate disease progression. Recent investigations into key regulatory pathways, including mechanistic target of rapamycin, sirtuins, and adenosine monophosphate-activated protein kinase, have considerably deepened our understanding of metabolic dysregulation and opened new avenues for therapeutic innovation. Emerging technologies, such as fluorescent probes, nano-biomaterials, and metabolomic analyses, promise substantial improvements in diagnostic precision. This review critically examines recent advancements and ongoing challenges in metabolism research, emphasizing its potential for precision diagnostics and personalized therapeutic interventions. Future studies should prioritize unraveling the regulatory mechanisms of energy metabolism and the dynamics of intercellular energy interactions. Integrating cutting-edge gene-editing technologies and multi-omics approaches, the development of multi-target pharmaceuticals in synergy with existing therapies such as immunotherapy and dietary interventions could enhance therapeutic efficacy. Personalized metabolic analysis is indispensable for crafting tailored treatment protocols, ultimately providing more accurate medical solutions for patients. This review aims to deepen the understanding and improve the application of energy metabolism to drive innovative diagnostic and therapeutic strategies.

Elocalcitol, a fluorinated vitamin D derivative, prevents high-fat diet-induced obesity via SCAP downregulation and miR-146a-associated mechanisms

Background

Obesity is an emerging health problem worldwide as it is associated with increased risk of cardiovascular, metabolic, mental disorders, and cancer. Therapeutic weight management remains one of the options for the treatment of excess weight and associated comorbidities. In this study, the therapeutic potential of elocalcitol, a fluorinated derivative of vitamin D, was studied on the model of high-fat diet (HFD)-induced obesity in mice.

Results

It was demonstrated that co-administration of elocalcitol in the doses 15 ug/kg (i.p.) twice a week for 16 weeks prevented body weight gain by approximately 15%. The significant retardation in the body weight gain was observed already on the second week of elocalcitol treatment. Administration of elocalcitol also reduced visceral and epididymal fat accumulation by 55% and 35%, respectively, metabolic syndrome development, and lipid droplets accumulation in the liver of mice exposed to HFD. In contrast, the administration of cholecalciferol (vitamin D)-a precursor to calcitriol, the biologically active form of vitamin D, did not affect significantly the signs of obesity and metabolic syndrome, suggesting that the anti-obese effects of elocalcitol are not related to the canonical vitamin D receptor (VDR). Further studies have demonstrated that the preventive effect of elocalcitol is associated with the decreased levels of sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP) and upregulation insulin-inducing gene-1 (Insig1) mRNA expression suggesting that the anti-obese effect of elocalcitol is mediated via inhibition of SREBP-mediated lipogenesis. We also demonstrated that elocalcitol prevents an increase in the expression of proinflammatory cytokines such as interleukin-1 beta (Il1b), tumor necrosis factor-alpha (Tnf), and interleukin-18 (Il18), and this effect was associated with upregulation of microRNA-146a (miR-146a). Deletion of the miR-146a gene reduced the anti-obese effects of elocalcitol and prevented its actions on the SCAP levels. The data indicate that elocalcitol's reduction of SCAP is at least partly mediated by miR-146a modulation.

Conclusion

The study demonstrates that elocalcitol prevents HFD-induced obesity and metabolic syndrome in mice, likely by inhibiting SREBP-mediated lipogenesis and upregulating miR-146a. These findings provide valuable insights into the anti-obesity mechanisms of fluorinated D-vitamin analogs and suggest potential therapeutic strategies for obesity prevention.

Lipidomics-based natural products for chronic kidney disease treatment

Chronic kidney disease (CKD) is by far the most prevalent disease in the world and is now a major global public health problem because of the increase in diabetes, hypertension and obesity. Traditional biomarkers of kidney function lack sensitivity and specificity for early detection and monitoring of CKD progression, necessitating more sensitive biomarkers for early diagnostic intervention. Dyslipidemia is a hallmark of CKD. Advancements in mass spectrometry (MS)-based lipidomics platforms have facilitated comprehensive analysis of lipids in biological samples and have revealed changes in the lipidome that are associated with metabolic disorders, which can be used as new biomarkers for kidney diseases. It is also critical for the discovery of new therapeutic targets and drugs. In this article, we focus on lipids in CKD, lipidomics methodologies and their applications in CKD. Additionally, we introduce novel biomarkers identified through lipidomics approaches and natural products derived from lipidomics for the treatment of CKD. We believe that our study makes a significant contribution to literature by demonstrating that natural products can improve CKD from a lipidomic perspective.

Peripheral myelin: From development to maintenance

Peripheral myelin is synthesized by glial cells called Schwann cells (SCs). SC development and differentiation must be tightly regulated to avoid any pathological consequence affecting peripheral nerve function. Neuropathic symptoms can arise from developmental issues in SCs, as well as in adult life through processes affecting mature SCs. In this review we focus on SC differentiation from the immature towards the myelinating and non-myelinating SC stages, defining molecular mechanisms outlining radial sorting, a multi-stepped event essential for immature SC differentiation and myelination. We also describe mechanisms regulating myelin sheath maintenance and SC homeostasis during aging. Finally, we will conclude with some remaining questions in the field of SC biology.

From fat to fire: The lipid-inflammasome connection

Inflammasomes are multiprotein complexes that play a crucial role in regulating immune responses by governing the activation of Caspase-1, the secretion of pro-inflammatory cytokines, and the induction of inflammatory cell death, pyroptosis. The inflammasomes are pivotal in effective host defense against a range of pathogens. Yet, overt activation of inflammasome signaling can be detrimental. The most well-studied NLRP3 inflammasome has the ability to detect a variety of stimuli including pathogen-associated molecular patterns, environmental irritants, and endogenous stimuli released from dying cells. Additionally, NLRP3 acts as a key sensor of cellular homeostasis and can be activated by disturbances in diverse metabolic pathways. Consequently, NLRP3 is considered a key player linking metabolic dysregulation to numerous inflammatory disorders such as gout, diabetes, and atherosclerosis. Recently, compelling studies have highlighted a connection between lipids and the regulation of NLRP3 inflammasome. Lipids are integral to cellular processes that serve not only in maintaining the structural integrity and subcellular compartmentalization, but also in contributing to physiological equilibrium. Certain lipid species are known to define NLRP3 subcellular localization, therefore directly influencing the site of inflammasome assembly and activation. For instance, phosphatidylinositol 4-phosphate plays a crucial role in NLRP3 localization to the trans Golgi network. Moreover, new evidence has demonstrated the roles of lipid biosynthesis and trafficking in activation of the NLRP3 inflammasome. This review summarizes and discusses these emerging and varied roles of lipid metabolism in inflammasome activation. A deeper understanding of lipid-inflammasome interactions may open new avenues for therapeutic interventions to prevent or treat chronic inflammatory and autoimmune conditions.

Diacylglycerol Kinases and Its Role in Lipid Metabolism and Related Diseases

Lipids are essential components of eukaryotic membranes, playing crucial roles in membrane structure, energy storage, and signaling. They are predominantly synthesized in the endoplasmic reticulum (ER) and subsequently transported to other organelles. Diacylglycerol kinases (DGKs) are a conserved enzyme family that phosphorylate diacylglycerol (DAG) to produce phosphatidic acid (PA), both of which are key intermediates in lipid metabolism and second messengers involved in numerous cellular processes. Dysregulation of DGK activity is associated with several diseases, including cancer and metabolic disorders. In this review, we provide a comprehensive overview of DGK types, functions, cellular localization, and their potential as therapeutic targets. We also discuss DGKs' roles in lipid metabolism and their physiological functions and related diseases.

Expression and correlation analysis of silent information regulator 1 (SIRT1), sterol regulatory element-binding protein-1 (SREBP1), and pyroptosis factor in gestational diabetes mellitus

BACKGROUND AND AIM

Globally, the prevalence of gestational diabetes mellitus (GDM) is rising each year, yet its pathophysiology is still unclear. To shed new light on the pathogenesis of gestational diabetes mellitus and perhaps uncover new therapeutic targets, this study looked at the expression levels and correlations of SIRT1, SREBP1, and pyroptosis factors like NLRP3, Caspase-1, IL-1, and IL-18 in patients with GDM.

METHODS

This study involved a comparative analysis between two groups. The GDM group consisted of 50 GDM patients and the control group included 50 pregnant women with normal pregnancies. Detailed case data were collected for all participants. We utilized real-time quantitative PCR and Western Blot techniques to assess the expression levels of SIRT1 and SREBP1 in placental tissues from both groups. Additionally, we employed an enzyme-linked immunosorbent assay to measure the serum levels of SIRT1, SREBP1, and pyroptosis factors, namely NLRP3, Caspase-1, IL-1β, and IL-18, in the patients of both groups. Subsequently, we analyzed the correlations between these factors and clinical.

RESULTS

The results showed that there were significantly lower expression levels of SIRT1 in both GDM group placental tissue and serum compared to the control group (p < 0.01). In contrast, the expression of SREBP1 was significantly higher in the GDM group than in the control group (p < 0.05). Additionally, the serum levels of NLRP3, Caspase-1, IL-1β, and IL-18 were significantly elevated in the GDM group compared to the control group (p < 0.01). The expression of SIRT1 exhibited negative correlations with the expression of FPG, OGTT-1h, FINS, HOMA-IR, SREBP1, IL-1β, and IL-18. However, there was no significant correlation between SIRT1 expression and OGTT-2h, NLRP3, or Caspase-1. On the other hand, the expression of SREBP1 was positively correlated with the expression of IL-1β, Caspase-1, and IL-18, but has no apparent correlation with NLRP3.

CONCLUSIONS

Low SIRT1 levels and high SREBP1 levels in placental tissue and serum, coupled with elevated levels of pyroptosis factors NLRP3, Caspase-1, IL-1β, and IL-18 in serum, may be linked to the development of gestational diabetes mellitus. Furthermore, these three factors appear to correlate with each other in the pathogenesis of GDM, offering potential directions for future research and therapeutic strategies.

Identification of Candidate Genes for Sebum Deposition in Pekin Ducks Using Genome-Wide Association Studies

BACKGROUND

Sebum deposition is a vital trait influencing meat quality and production efficiency in Pekin ducks. Providing insights into the genetic basis of fat deposition could help improve breeding strategies aimed at producing high-quality meat ducks. This study aimed to identify the genetic mechanisms and lipid metabolism pathways regulating subcutaneous and intramuscular fat deposition in two Pekin duck strains: Nankou No. 1 and Jingdian.

METHODS

A total of 72 male ducks, Nankou No. 1 (n = 36) and Jingdian (n = 36), were raised under controlled conditions for 42 days. On days 28, 35, and 42, ducks from each group were selected and slaughtered, and their subcutaneous and liver tissues were collected to analyze lipid enzyme activities. On day 42, additional ducks from each strain were slaughtered and evaluated for carcass performance, as well as intramuscular and sebum yield. Genome-wide association analysis (GWAS) was conducted in the Nankou No. 1 strain.

CONCLUSION

Our results showed statistically significant differences in intramuscular and subcutaneous fat yield between the two strains, with Nankou No. 1 exhibiting a higher yield than Jingdian (p < 0.05). The GWAS results identified 96 significant single nucleotide polymorphisms (SNPs), associated with sebum deposition. Functional annotation identified ALDH7A1 as a key candidate gene involved in lipid metabolism and fat storage regulation in Pekin ducks, Nankou No. 1 strain. Enzyme activity assays in liver and subcutaneous tissues revealed breed-specific differences in lipid metabolism, aligning with genetic findings. The activities of the lipid enzymes changed over time, suggesting changes in the developmental stages. The results on fat yield and enzymatic activities further align with molecular findings from the GWAS, which identified variations in lipid metabolism pathways. These results highlight genetic markers and biochemical pathways related to fat deposition in Pekin ducks, offering new insights for selective breeding programs aimed at optimizing fat content in meat production. Further research is needed to clarify the specific role of ALDH7A1 in lipid metabolism and its potential to enhance fat deposition traits in poultry.

Unlocking secrets: lipid metabolism and lipid droplet crucial roles in SARS-CoV-2 infection and the immune response

Lipid droplets (LDs) are crucial for maintaining lipid and energy homeostasis within cells. LDs are highly dynamic organelles that present a phospholipid monolayer rich in neutral lipids. Additionally, LDs are associated with structural and nonstructural proteins, rapidly mobilizing lipids for various biological processes. Lipids play a pivotal role during viral infection, participating during viral membrane fusion, viral replication, and assembly, endocytosis, and exocytosis. SARS-CoV-2 infection often induces LD accumulation, which is used as a source of energy for the replicative process. These findings suggest that LDs are a hallmark of viral infection, including SARS-CoV-2 infection. Moreover, LDs participate in the inflammatory process and cell signaling, activating pathways related to innate immunity and cell death. Accumulating evidence demonstrates that LD induction by SARS-CoV-2 is a highly coordinated process, aiding replication and evading the immune system, and may contribute to the different cell death process observed in various studies. Nevertheless, recent research in the field of LDs suggests these organelles according to the pathogen and infection conditions may also play roles in immune and inflammatory responses, protecting the host against viral infection. Understanding how SARS-CoV-2 influences LD biogenesis is crucial for developing novel drugs or repurposing existing ones. By targeting host lipid metabolic pathways exploited by the virus, it is possible to impact viral replication and inflammatory responses. This review seeks to discuss and analyze the role of LDs during SARS-CoV-2 infection, specifically emphasizing their involvement in viral replication and the inflammatory response.

PCK1 as a target for cancer therapy: from metabolic reprogramming to immune microenvironment remodeling

Recently, changes in metabolites and metabolism-related enzymes related to tumor cell proliferation, metastasis, drug resistance, and immunosuppression have become a research hotspot, and researchers have attempted to determine the clinical correlation between specific molecular lesions and metabolic phenotypes. Convincing evidence shows that metabolic reprogramming is closely related to the proliferation, invasion, metastasis, and poor prognosis of malignant tumors. Therefore, targeting metabolic reprogramming is a new direction for cancer treatment. However, how molecular alterations in tumors contribute to metabolic diversity and unique targeting dependencies remains unclear. A full understanding of the underlying mechanisms of metabolic reprogramming in cancer may lead to better identification of therapeutic targets and the development of therapeutic strategies. Evidence for the importance of PCK1, a phosphoenolpyruvate carboxykinase 1, in tumorigenesis and development is accumulating. PCK1 can regulate cell proliferation and metastasis by remodeling cell metabolism. Additionally, PCK1 has "nonclassical" nonmetabolic functions, involving the regulation of gene expression, angiogenesis, epigenetic modification, and other processes, and has an impact on cell survival, apoptosis, and other biological activities, as well as the remodeling of the tumor immune microenvironment. Herein, we provide a comprehensive overview of the functions of PCK1 under physiological and pathological conditions and suggest that PCK1 is a potential target for cancer therapy. We also propose a future exploration direction for targeting PCK1 for cancer therapy from a clinical perspective. Finally, in view of the collective data, the results of our discussion suggest the potential clinical application of targeted PCK1 therapy in combination with chemotherapy and immunotherapy for cancer treatment.

Roles of posttranslational modifications in lipid metabolism and cancer progression

Lipid metabolism reprogramming has emerged as a hallmark of malignant tumors. Lipids represent a complex group of biomolecules that not only compose the essential components of biological membranes and act as an energy source, but also function as messengers to integrate various signaling pathways. In tumor cells, de novo lipogenesis plays a crucial role in acquiring lipids to meet the demands of rapid growth. Increasing evidence has suggested that dysregulated lipid metabolism serves as a driver of cancer progression. Posttranslational modifications (PTMs), which occurs in most eukaryotic proteins throughout their lifetimes, affect the activity, abundance, function, localization, and interactions of target proteins. PTMs of crucial molecules are potential intervention sites and are emerging as promising strategies for the cancer treatment. However, there is limited information available regarding the PTMs that occur in cancer lipid metabolism and the potential treatment strategies associated with these PTMs. Herein, we summarize current knowledge of the roles and regulatory mechanisms of PTMs in lipid metabolism. Understanding the roles of PTMs in lipid metabolism in cancer could provide valuable insights into tumorigenesis and progression. Moreover, targeting PTMs in cancer lipid metabolism might represent a promising novel therapeutic strategy.

The potential role of transcription factor sterol regulatory element binding proteins (SREBPs) in Alzheimer's disease

Sterol regulatory element binding proteins (SREBPs) are a series of cholesterol-related transcription factors. Their role in regulating brain cholesterol biosynthesis, amyloid accumulation, and tau tangles formation has been intensively studied in protein-protein interaction analysis based on genes in clinical databases. SREBPs play an important role in maintaining cholesterol homeostasis in the brain. There are three subtypes of SREBPs, SREBP-1a stimulates the expression of genes related to cholesterol and fatty acid synthesis, SREBP-1c stimulates adipogenesis, and SREBP-2 stimulates cholesterol synthase and LDL receptors. SREBP-2 is activated in response to cholesterol depletion and stimulates a compensatory upregulation of cholesterol uptake and synthesis. Previous studies have shown that inhibition of SREBP-2 reduces cholesterol and amyloid accumulation, and new research suggests that SREBPs play a multifaceted role in Alzheimer's disease. Here, we highlight the importance of SREBPs in AD, in terms of multiple pathways regulating cholesterol in the brain, and primarily demonstrate the potential of SREBP-2 inhibitors. There was a trend towards a significant increase in the expression levels of different SREBP isoforms in AD patients compared to healthy controls. Therefore, there is a close link between SREBPs and AD, and this review analyses the potential role of SREBPs in the treatment of AD. In addition, we systematically reviewed the research progress of SREBPs in AD, and this review will provide more innovative insights into the pathogenesis and treatment of AD and new strategies for drug development in AD.

Effect of Abelmoschus esculentus L. (Okra) on Dyslipidemia: Systematic Review and Meta-Analysis of Clinical Studies

The global prevalence of cardiovascular diseases (CVDs), including dyslipidemia and atherosclerosis, is rising. While pharmacological treatments for dyslipidemia and associated CVDs exist, not all individuals can afford them, and those who do often experience adverse side effects. Preclinical studies have indicated the potential benefits of Abelmoschus esculentus and its active phytochemicals in addressing dyslipidemia in rodent models of diabetes. However, there is limited clinical evidence on lipid parameters. Thus, this study aimed to assess the potential impact of Abelmoschus esculentus on dyslipidemia. A literature search was performed on PubMed, Scopus, and Cochrane Library for relevant trials published from inception until 11 August 2024. Data analysis was performed using Jamovi software version 2.4.8 and Review Manager (version 5.4), with effect estimates reported as standardized mean differences (SMDs) and 95% confidence intervals (CI). The evidence from eight studies with nine treatment arms showed that Abelmoschus esculentus reduces total cholesterol (TC), SMD = -0.53 (95% CI: -1.00 to -0.07), p = 0.025), compared to placebo. Additionally, triglyceride (TG) was reduced in Abelmoschus esculentus compared to placebo, SMD = -0.24 (95% CI: -0.46 to -0.02), p = 0.035. Furthermore, low-density lipoprotein (LDL) was also reduced, SMD = -0.35 (95% CI: -0.59 to -0.11), p = 0.004 in Abelmoschus esculentus versus placebo. This remedy substantially increased high-density lipoprotein (HDL), SMD = 0.34 (95% CI: 0.07 to 0.61), p = 0.014). Abelmoschus esculentus substantially improved lipid profile in prediabetes, T2D, obesity, and diabetic nephropathy. While the evidence confirms the potential benefits of Abelmoschus esculentus in reducing dyslipidemia, it is important for future clinical studies to standardize the effective dosage for more reliable results. Therefore, future trials should focus on these markers in well-designed trials with sufficient sample sizes. Furthermore, Abelmoschus esculentus can be supplemented to the diet of the relevant populations to alleviate dyslipidemia.

De novo lipid synthesis and polarized prenylation drive cell invasion through basement membrane

To breach the basement membrane, cells in development and cancer use large, transient, specialized lipid-rich membrane protrusions. Using live imaging, endogenous protein tagging, and cell-specific RNAi during Caenorhabditis elegans anchor cell (AC) invasion, we demonstrate that the lipogenic SREBP transcription factor SBP-1 drives the expression of the fatty acid synthesis enzymes POD-2 and FASN-1 prior to invasion. We show that phospholipid-producing LPIN-1 and sphingomyelin synthase SMS-1, which use fatty acids as substrates, produce lysosome stores that build the AC's invasive protrusion, and that SMS-1 also promotes protrusion localization of the lipid raft partitioning ZMP-1 matrix metalloproteinase. Finally, we discover that HMG-CoA reductase HMGR-1, which generates isoprenoids for prenylation, localizes to the ER and enriches in peroxisomes at the AC invasive front, and that the final transmembrane prenylation enzyme, ICMT-1, localizes to endoplasmic reticulum exit sites that dynamically polarize to deliver prenylated GTPases for protrusion formation. Together, these results reveal a collaboration between lipogenesis and a polarized lipid prenylation system that drives invasive protrusion formation.

β-sitosterol alleviates high fatty acid-induced lipid accumulation in calf hepatocytes by regulating cholesterol metabolism

A significant reduction in plasma concentration of cholesterol during early lactation is a common occurrence in high-yielding dairy cows. An insufficient synthesis of cholesterol in the liver has been linked to lipid accumulation caused by high concentrations of fatty acids during negative energy balance (NEB). As ruminant diets do not provide quantitative amounts of cholesterol for absorption, phytosterols such as β-sitosterol may serve to mitigate the shortfall in cholesterol within the liver during NEB. To gain mechanistic insights, primary hepatocytes were isolated from healthy female 1-day old calves for in vitro studies with or without 1.2 mM fatty acids (FA) to induce metabolic stress. Furthermore, hepatocytes were treated with 50 μM β-sitosterol with or without FA. Data were analyzed by one-way ANOVA with subsequent Bonferroni correction. Results revealed that calf hepatocytes treated with FA had greater content of non-esterified fatty acids (NEFA) and triacylglycerol (TAG), and greater mRNA and protein abundance of the lipid synthesis-related SREBF1 and FASN. In contrast, mRNA and protein of CPT1A (fatty acid oxidation) and the cholesterol metabolism-related targets SREBF2, HMGCR, ACAT2, APOA1, ABCA1 and ABCG5 was lower. Content of the antioxidant-related glutathione (GSH) and activities of superoxide dismutase (SOD) also was lower. Compared with FA challenge alone, 50 μM β-sitosterol led to greater mRNA and protein abundance of SREBF2, HMGCR, ACAT2 and ABCG5, and greater content of GSH and activity of SOD. In contrast, compared with the FA group, the mRNA and protein abundance of SREBF1 and ACC1 and the content of TAG and NEFA in the β-sitosterol + FA group were lower. Overall, β-sitosterol can promote cholesterol metabolism and reduce oxidative stress while reducing lipid accumulation in hepatocytes challenged with high concentrations of fatty acids.

Inhibition of PCSK9: A Promising Enhancer for Anti-PD-1/PD-L1 Immunotherapy

Immune checkpoint therapy, such as programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1) blockade, has achieved remarkable results in treating various tumors. However, most cancer patients show a low response rate to PD-1/PD-L1 blockade, especially those with microsatellite stable/mismatch repair-proficient colorectal cancer subtypes, which indicates an urgent need for new approaches to augment the efficacy of PD-1/PD-L1 blockade. Cholesterol metabolism, which involves generating multifunctional metabolites and essential membrane components, is also instrumental in tumor development. In recent years, inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9), a serine proteinase that regulates cholesterol metabolism, has been demonstrated to be a method enhancing the antitumor effect of PD-1/PD-L1 blockade to some extent. Mechanistically, PCSK9 inhibition can maintain the recycling of major histocompatibility protein class I, promote low-density lipoprotein receptor-mediated T-cell receptor recycling and signaling, and modulate the tumor microenvironment (TME) by affecting the infiltration and exclusion of immune cells. These mechanisms increase the quantity and enhance the antineoplastic effect of cytotoxic T lymphocyte, the main functional immune cells involved in anti-PD-1/PD-L1 immunotherapy, in the TME. Therefore, combining PCSK9 inhibition therapy with anti-PD-1/PD-L1 immunotherapy may provide a novel option for improving antitumor effects and may constitute a promising research direction. This review concentrates on the relationship between PCSK9 and cholesterol metabolism, systematically discusses how PCSK9 inhibition potentiates PD-1/PD-L1 blockade for cancer treatment, and highlights the research directions in this field.

Lipid metabolism reprogramming in endometrial cancer: biological functions and therapeutic implications

BACKGROUND

Endometrial cancer is one of the major gynecological cancers, with increasing incidence and mortality in the past decades. Emerging preclinical and clinical data have indicated its close association with obesity and dyslipidemia. Metabolism reprogramming has been considered as the hallmark of cancer, to satisfy the extensive need of nutrients and energy for survival and growth. Particularly, lipid metabolism reprogramming has aroused the researchers' interest in the field of cancer, including tumorigenesis, invasiveness, metastasis, therapeutic resistance and immunity modulation, etc. But the roles of lipid metabolism reprogramming in endometrial cancer have not been fully understood. This review has summarized how lipid metabolism reprogramming induces oncogenesis and progression of endometrial cancer, including the biological functions of aberrant lipid metabolism pathway and altered transcription regulation of lipid metabolism pathway. Besides, we proposed novel therapeutic strategies of targeting lipid metabolism pathway and concentrated on its potential of sensitizing immunotherapy and hormonal therapy, to further optimize the existing treatment modalities of patients with advanced/metastatic endometrial cancer. Moreover, we expect that targeting lipid metabolism plus hormone therapy may block the endometrial malignant transformation and enrich the preventative approaches of endometrial cancer.

CONCLUSION

Lipid metabolism reprogramming plays an important role in tumor initiation and cancer progression of endometrial cancer. Targeting the core enzymes and transcriptional factors of lipid metabolism pathway alone or in combination with immunotherapy/hormone treatment is expected to decrease the tumor burden and provide promising treatment opportunity for patients with advanced/metastatic endometrial cancer.

Ubiquitination and De-Ubiquitination in the Synthesis of Cow Milk Fat: Reality and Prospects

Ubiquitination modifications permit the degradation of labelled target proteins with the assistance of proteasomes and lysosomes, which is the main protein degradation pathway in eukaryotic cells. Polyubiquitination modifications of proteins can also affect their functions. De-ubiquitinating enzymes reverse the process of ubiquitination via cleavage of the ubiquitin molecule, which is known as a de-ubiquitination. It was demonstrated that ubiquitination and de-ubiquitination play key regulatory roles in fatty acid transport, de novo synthesis, and desaturation in dairy mammary epithelial cells. In addition, natural plant extracts, such as stigmasterol, promote milk fat synthesis in epithelial cells via the ubiquitination pathway. This paper reviews the current research on ubiquitination and de-ubiquitination in dairy milk fat production, with a view to providing a reference for subsequent research on milk fat and exploring new directions for the improvement of milk quality.

Regulation of cholesterol biosynthesis by CTCF and H3K27 methylation is critical for cell migration

CTCF is a key factor in three-dimensional chromatin folding and transcriptional control that was found to affect cancer cell migration by a mechanism that is still poorly understood. To identify this mechanism, we used mouse melanoma cells with a partial loss of function (pLoF) of CTCF. We found that CTCF pLoF inhibits cell migration rate while leading to an increase in the expression of multiple enzymes in the cholesterol biosynthesis pathway along with an elevation in the cellular cholesterol level. In agreement with the cholesterol change we detected altered membrane dynamics in CTCF pLoF cells as measured by reduced formation of migrasomes, extracellular vesicles formed at the rear side of migrating cells. Inhibition of cholesterol synthesis in CTCF pLoF cells restored the cellular migration rate and migrasome formation, suggesting that CTCF supports cell migration by suppressing cholesterol synthesis. Detailed analysis of the promoter of Hmgcs1, an early enzyme in the cholesterol synthesis pathway, revealed that CTCF prevents formation of a loop between that promoter and another promoter 200 kb away. CTCF also supports PRC2 recruitment to the promoter and deposition of H3K27me3. H3K27me3 at the promoter of Hmgcs1 prevents SREBP2 binding and activation of transcription. By this mechanism, CTCF fine-tunes cholesterol levels to support cell migration. Notably, genome wide association studies suggest a link between CTCF and cholesterol-associated diseases, thus CTCF emerges as a new regulator of cholesterol biosynthesis.

Cholesterol-ferroptosis nexus: Unveiling novel cancer therapeutic avenues

Ferroptosis, a novel form of regulated cell death characterized by iron-mediated lipid peroxidation, holds immense potential in cancer therapeutics due to its role in tumor progression and resistance. This review predominantly explores the intricate relationship between ferroptosis and cholesterol metabolism pathways, mainly focusing on the cholesterol biosynthesis pathway. This review highlights the therapeutic implications of targeting cholesterol metabolism pathways for cancer treatment by delving into the mechanisms underlying ferroptosis regulation. Strategies such as inhibiting HMG-CoA reductase and suppressing squalene synthesis offer promising avenues for inducing ferroptosis in cancer cells. Moreover, insights into targeting the 7-dehydrocholesterol pathway provide novel perspectives on modulating ferroptosis susceptibility and managing ferroptosis-associated diseases. Understanding the interplay between ferroptosis and cholesterol metabolism pathways underscores the potential of lipid metabolism modulation as an innovative therapeutic approach in cancer treatment.

Liver epigenomic signature associated with chronic oxidative stress in a mouse model of glutathione deficiency

Oxidative stress is intimately involved in the pathogenesis of fatty liver disease (FLD). A major factor contributing to oxidative stress is the depletion of the ubiquitous antioxidant glutathione (GSH). Unexpectedly, chronic GSH deficiency renders glutamate-cysteine ligase modifier subunit (Gclm)-null mice protected from fatty liver injuries. Epigenetic regulation serves as an important cellular mechanism in modulating gene expression and disease outcome in FLD, although it is not well understood how systemic redox imbalance modifies the liver epigenome. In the current study, utilizing the Gclm-null mouse model, we aimed to elucidate redox-associated epigenomic changes and their implications in liver stress response. We performed high-throughput array-based DNA methylation profiling (MeDIP array) in 22,327 gene promoter regions (from -1300 bp to +500 bp of the Transcription Start Sites) in the liver and peripheral blood cells. Results from the MeDIP array demonstrate that, although global methylation enrichment in gene promoters did not change, low GSH resulted in prevalent demethylation at the individual promoter level. Such an effect likely attributed to a declined availability of the methyl donor S-adenosyl methionine (SAM) in Gclm-null liver. Functional enrichment analysis of liver target genes is suggestive of a potential role of epigenetic mechanisms in promoting cellular survival and lipid homeostasis in Gclm-null liver. In comparison with the liver tissue, MeDIP array in peripheral blood cells revealed a panel of 19 gene promoters that are candidate circulating biomarkers for hepatic epigenomic changes associated with chronic GSH deficiency. Collectively, our results provided new insights into the in vivo interplay between liver redox state and DNA methylation status. The current study laid the groundwork for future epigenetic/epigenomic investigations in experimental settings or human populations under conditions of liver oxidative stress induced by environmental or dietary challenges.

The cellular and molecular targets of natural products against metabolic disorders: a translational approach to reach the bedside

Metabolic disorders, including obesity, dyslipidemia, diabetes, nonalcoholic fatty liver disease, and metabolic syndrome, are characterized by insulin resistance, abnormalities in circulating cholesterol and lipid profiles, and hypertension. The most common pathophysiologies of metabolic disorders are glucose/lipid metabolism dysregulation, insulin resistance, inflammatory response, and oxidative stress. Although several agents have been approved for the treatment of metabolic disorders, there is still a strong demand for more efficacious drugs with less side effects. Natural products have been critical sources of drug research and discovery for decades. However, the usefulness of bioactive natural products is often limited by incomplete understanding of their direct cellular targets. In this review, we highlight the current understanding of the established and emerging molecular mechanisms of metabolic disorders. We further summarize the therapeutic effects and underlying mechanisms of natural products on metabolic disorders, with highlights on their direct cellular targets, which are mainly implicated in the regulation of glucose/lipid metabolism, insulin resistance, metabolic inflammation, and oxidative stress. Finally, this review also covers the clinical studies of natural products in metabolic disorders. These progresses are expected to facilitate the application of these natural products and their derivatives in the development of novel drugs against metabolic disorders.

Cholesterol 25-Hydroxylase Protects Against Diabetic Kidney Disease by Regulating ADP Ribosylation Factor 4

Cholesterol 25-hydroxylase (CH25H), an enzyme involved in cholesterol metabolism, regulates inflammatory responses and lipid metabolism. However, its role in kidney disease is not known.  The author found that CH25H transcript is expressed mostly in glomerular and peritubular endothelial cells and that its expression increased in human and mouse diabetic kidneys.  Global deletion of Ch25h in Leprdb/db mice aggravated diabetic kidney disease (DKD), which is associated with increased endothelial cell apoptosis. Treatment of 25-hydroxycholesterol (25-HC), the product of CH25H, alleviated kidney injury in Leprdb/db mice. Mechanistically, 25-HC binds to GTP-binding protein ADP-ribosylation factor 4 (ARF4), an essential protein required for maintaining protein transport in the Golgi apparatus. Interestingly, ARF4's GTPase-activating protein ASAP1 is also predominantly expressed in endothelial cells and its expression increased in DKD. Suppression of ARF4 activity by deleting ARF4 or overexpressing ASAP1 results in endothelial cell death. These results indicate that 25-HC binds ARF4 to inhibit its interaction with ASAP1, and thereby resulting in enhanced ARF4 activity to confer renoprotection. Therefore, treatment of 25-HC improves kidney injury in DKD in part by restoring ARF4 activity to maintain endothelial cell survival. This study provides a novel mechanism and a potential new therapy for DKD.

Lysine methylation modifications in tumor immunomodulation and immunotherapy: regulatory mechanisms and perspectives

Lysine methylation is a crucial post-translational modification (PTM) that significantly impacts gene expression regulation. This modification not only influences cancer development directly but also has significant implications for the immune system. Lysine methylation modulates immune cell functions and shapes the anti-tumor immune response, highlighting its dual role in both tumor progression and immune regulation. In this review, we provide a comprehensive overview of the intrinsic role of lysine methylation in the activation and function of immune cells, detailing how these modifications affect cellular processes and signaling pathways. We delve into the mechanisms by which lysine methylation contributes to tumor immune evasion, allowing cancer cells to escape immune surveillance and thrive. Furthermore, we discuss the therapeutic potential of targeting lysine methylation in cancer immunotherapy. Emerging strategies, such as immune checkpoint inhibitors (ICIs) and chimeric antigen receptor T-cell (CAR-T) therapy, are being explored for their efficacy in modulating lysine methylation to enhance anti-tumor immune responses. By targeting these modifications, we can potentially improve the effectiveness of existing treatments and develop novel therapeutic approaches to combat cancer more effectively.

Exome-wide association analysis identifies novel risk loci for alcohol-associated hepatitis

BACKGROUND AND AIMS

Alcohol-associated hepatitis (AH) is a clinically severe, acute disease that afflicts only a fraction of patients with alcohol use disorder. Genomic studies of alcohol-associated cirrhosis (AC) have identified several genes of large effect, but the genetic and environmental factors that lead to AH and AC, and their degree of genetic overlap, remain largely unknown. This study aims to identify genes and genetic variations that contribute to the development of AH.

APPROACH AND RESULTS

Exome-sequencing of patients with AH (N=784) and heavy drinking controls (N=951) identified an exome-wide significant association for AH at patalin-like phospholipase domain containing 3, as previously observed for AC in genome-wide association study, although with a much lower effect size. Single nucleotide polymorphisms (SNPs) of large effect size at inducible T cell costimulatory ligand ( ICOSLG ) (Chr 21) and TOX4/RAB2B (Chr 14) were also exome-wide significant. ICOSLG encodes a co-stimulatory signal for T-cell proliferation and cytokine secretion and induces B-cell proliferation and differentiation. TOX high mobility group box family member 4 ( TOX4 ) was previously implicated in diabetes and immune system function. Other genes previously implicated in AC did not strongly contribute to AH, and the only prominently implicated (but not exome-wide significant) gene overlapping with alcohol use disorder was alcohol dehydrogenase 1B ( ADH1B ). Polygenic signals for AH were observed in both common and rare variant analysis and identified genes with roles associated with inflammation.

CONCLUSIONS

This study has identified 2 new genes of high effect size with a previously unknown contribution to alcohol-associated liver disease and highlights both the overlap in etiology between liver diseases and the unique origins of AH.

The lncRNA LINC01605 promotes the progression of pancreatic ductal adenocarcinoma by activating the mTOR signaling pathway

BACKGROUND

This study investigated the molecular mechanism of long intergenic non-protein coding RNA 1605 (LINC01605) in the process of tumor growth and liver metastasis of pancreatic ductal adenocarcinoma (PDAC).

METHODS

LINC01605 was filtered out with specificity through TCGA datasets (related to DFS) and our RNA-sequencing data of PDAC tissue samples from Renji Hospital. The expression level and clinical relevance of LINC01605 were then verified in clinical cohorts and samples by immunohistochemical staining assay and survival analysis. Loss- and gain-of-function experiments were performed to estimate the regulatory effects of LINC01605 in vitro. RNA-seq of LINC01605-knockdown PDAC cells and subsequent inhibitor-based cellular function, western blotting, immunofluorescence and rescue experiments were conducted to explore the mechanisms by which LINC01605 regulates the behaviors of PDAC tumor cells. Subcutaneous xenograft models and intrasplenic liver metastasis models were employed to study its role in PDAC tumor growth and liver metastasis in vivo.

RESULTS

LINC01605 expression is upregulated in both PDAC primary tumor and liver metastasis tissues and correlates with poor clinical prognosis. Loss and gain of function experiments in cells demonstrated that LINC01605 promotes the proliferation and migration of PDAC cells in vitro. In subsequent verification experiments, we found that LINC01605 contributes to PDAC progression through cholesterol metabolism regulation in a LIN28B-interacting manner by activating the mTOR signaling pathway. Furthermore, the animal models showed that LINC01605 facilitates the proliferation and metastatic invasion of PDAC cells in vivo.

CONCLUSIONS

Our results indicate that the upregulated lncRNA LINC01605 promotes PDAC tumor cell proliferation and migration by regulating cholesterol metabolism via activation of the mTOR signaling pathway in a LIN28B-interacting manner. These findings provide new insight into the role of LINC01605 in PDAC tumor growth and liver metastasis as well as its value for clinical approaches as a metabolic therapeutic target in PDAC.

Exposure to Gulf war illness-related chemicals exacerbates alcohol-induced liver damage in rodents

Gulf War Illness (GWI) describes a series of symptoms suffered by veterans of the Gulf war, consisting of cognitive, neurological and gastrointestinal dysfunctions. Two chemicals associated with GWI are the insecticide permethrin (PER) and the nerve gas prophylactic pyridostigmine-bromide (PB). In this study we assessed the effects of PER and PB exposure on the pathology and subsequent alcohol (EtOH)-induced liver injury, and the influence of a macrophage depletor, PLX3397, on EtOH-induced liver damage in PER/PB-treated mice. Male C57BL/6 mice were injected daily with vehicle or PER/PB for 10 days, followed by 4 months recovery, then treatment with PLX3397 and a chronic-plus-single-binge EtOH challenge for 10 days. PER/PB exposure resulted in the protracted increase in liver transaminases in the serum and induced chronic low-level microvesicular steatosis and inflammation in GWI vs Naïve mice up to 4 months after cessation of exposure. Furthermore, prior exposure to PER/PB also resulted in exacerbated response to EtOH-induced liver injury, with enhanced steatosis, ductular reaction and fibrosis. The enhanced EtOH-induced liver damage in GWI-mice was attenuated by strategies designed to deplete macrophages in the liver. Taken together, these data suggest that exposure to GWI-related chemicals may alter the liver's response to subsequent ethanol exposure.

Lipid metabolism dynamics in cancer stem cells: potential targets for cancers

Cancer stem cells (CSCs) represent a small subset of heterogeneous cells within tumors that possess the ability to self-renew and initiate tumorigenesis. They serve as potential drivers for tumor initiation, metastasis, recurrence, and drug resistance. Recent research has demonstrated that the stemness preservation of CSCs is heavily reliant on their unique lipid metabolism alterations, enabling them to maintain their own environmental homeostasis through various mechanisms. The primary objectives involve augmenting intracellular fatty acid (FA) content to bolster energy supply, promoting β-oxidation of FA to optimize energy utilization, and elevating the mevalonate (MVA) pathway for efficient cholesterol synthesis. Additionally, lipid droplets (LDs) can serve as alternative energy sources in the presence of glycolysis blockade in CSCs, thereby safeguarding FA from peroxidation. Furthermore, the interplay between autophagy and lipid metabolism facilitates rapid adaptation of CSCs to the harsh microenvironment induced by chemotherapy. In this review, we comprehensively review recent studies pertaining to lipid metabolism in CSCs and provide a concise overview of the indispensable role played by LDs, FA, cholesterol metabolism, and autophagy in maintaining the stemness of CSCs.

Exserolide J ameliorates lipid accumulation in vitro by regulating liver X receptor alpha and peroxisome proliferator-activated receptor alpha proteins

Exserolides are isocoumarin derivatives containing lactone moiety. Recently, some isocoumarins have been demonstrated to ameliorate hyperlipidemia, a major factor for inducing cardiovascular diseases. However, the effects and mechanisms of action of exserolides on hyperlipidemia are not known. The aim of this study is to investigate whether the marine fungus Setosphaeria sp.-derived exserolides (compounds I, J, E, and F) exert lipid-lowering effects via improving reverse cholesterol transport (RCT) in vitro. RAW264.7 macrophages and HepG2 cells were used to establish lipid-laden models, and the levels of intracellular lipids and RCT-related proteins were determined by assay kits and Western blotting, respectively. We observed that exserolides (at a 5 μM concentration) significantly decreased intracellular cholesterol and triglyceride levels in oxidized low-density lipoprotein-laden RAW264.7 cells and markedly improved [3H]-cholesterol efflux. Among the four tested compounds, exserolide J increased the protein levels of ATP-binding cassette transporter A1, peroxisome proliferator-activated receptor α (PPARα), and liver X receptor α (LXRα). Furthermore, treatment with exserolides significantly decreased oleic acid-laden lipid accumulation in HepG2 hepatocytes. Mechanistically, exserolides enhance PPARα protein levels; furthermore, compound J increases cholesterol 7 alpha-hydroxylase A1 and LXRα protein levels. Molecular docking revealed that exserolides, particularly compound J, can interact with PPARα and LXRα proteins. These data suggest that the terminal carboxyl group of compound J plays a key role in lowering lipid levels by stimulating LXRα and PPARα proteins. In conclusion, compound J exhibits powerful lipid-lowering effects in vitro. However, its hypolipidemic effects in vivo should be investigated in the future.

Whole-genome sequencing identifies variants in ANK1, LRRN1, HAS1, and other genes and regulatory regions for stroke in type 1 diabetes

Individuals with type 1 diabetes (T1D) carry a markedly increased risk of stroke, with distinct clinical and neuroimaging characteristics as compared to those without diabetes. Using whole-exome or whole-genome sequencing of 1,051 individuals with T1D, we aimed to find rare and low-frequency genomic variants associated with stroke in T1D. We analysed the genome comprehensively with single-variant analyses, gene aggregate analyses, and aggregate analyses on genomic windows, enhancers and promoters. In addition, we attempted replication in T1D using a genome-wide association study (N = 3,945) and direct genotyping (N = 3,263), and in the general population from the large-scale population-wide FinnGen project and UK Biobank summary statistics. We identified a rare missense variant on SREBF1 exome-wide significantly associated with stroke (rs114001633, p.Pro227Leu, p-value = 7.30 × 10-8), which replicated for hemorrhagic stroke in T1D. Using gene aggregate analysis, we identified exome-wide significant genes: ANK1 and LRRN1 displayed replication evidence in T1D, and LRRN1, HAS1 and UACA in the general population (UK Biobank). Furthermore, we performed sliding-window analyses and identified 14 genome-wide significant windows for stroke on 4q33-34.1, of which two replicated in T1D, and a suggestive genomic window on LINC01500, which replicated in T1D. Finally, we identified a suggestively stroke-associated TRPM2-AS promoter (p-value = 5.78 × 10-6) with borderline significant replication in T1D, which we validated with an in vitro cell-based assay. Due to the rarity of the identified genetic variants, future replication of the genomic regions represented here is required with sequencing of individuals with T1D. Nevertheless, we here report the first genome-wide analysis on stroke in individuals with diabetes.

ATP Citrate Lyase Supports Cardiac Function and NAD+/NADH Balance And Is Depressed in Human Heart Failure

BACKGROUND

ATP-citrate lyase (ACLY) converts citrate into acetyl-CoA and oxaloacetate in the cytosol. It plays a prominent role in lipogenesis and fat accumulation coupled to excess glucose, and its inhibition is approved for treating hyperlipidemia. In RNAseq analysis of human failing myocardium, we found ACLY gene expression is reduced; however the impact this might have on cardiac function and/or metabolism has not been previously studied. As new ACLY inhibitors are in development for cancer and other disorders, such understanding has added importance.

METHODS

Cardiomyocytes, ex-vivo beating hearts, and in vivo hearts with ACLY inhibited by selective pharmacologic (BMS303141, ACLYi) or genetic suppression, were studied. Regulation of ACLY gene/protein expression, and effects of ACLYi on function, cytotoxicity, tricarboxylic acid (TCA)-cycle metabolism, and redox and NAD+/NADH balance were assessed. Mice with cardiac ACLY knockdown induced by AAV9-acly-shRNA or cardiomyocyte tamoxifen-inducible Acly knockdown were studied.

RESULTS

Acly gene expression was reduced more in obese patients with heart failure and preserved EF (HFpEF) than HF with reduced EF. In vivo pressure-overload and in vitro hormonal stress increased ACLY protein expression, whereas it declined upon fatty-acid exposure. Acute ACLYi (1-hr) dose-dependently induced cytotoxicity in adult and neonatal cardiomyocytes, and caused substantial reduction of systolic and diastolic function in myocytes and ex-vivo beating hearts. In the latter, ATP/ADP ratio also fell and lactate increased. U13C-glucose tracing revealed an ACLYdependent TCA-bypass circuit in myocytes, where citrate generated in mitochondria is transported to the cytosol, metabolized by ACLY and then converted to malate to re-enter mitochondria,bypassing several NADH-generating steps. ACLYi lowered NAD+/NADH ratio and restoring this balance ameliorated cardiomyocyte toxicity. Oxidative stress was undetected with ACLYi. Adult hearts following 8-weeks of reduced cardiac and/or cardiomyocyte ACLY downregulation exhibited ventricular dilation and reduced function that was prevented by NAD augmentation. Cardiac dysfunction from ACLY knockdown was worse in hearts subjected to sustained pressureoverload, supporting a role in stress responses.

CONCLUSIONS

ACLY supports normal cardiac function through maintenance of the NAD+/NADH balance and is upregulated by hemodynamic and hormonal stress, but depressed by lipid excess. ACLY levels are most reduced in human HFpEF with obesity potentially worsening cardio-metabolic reserve.

The prognostic significance of insulin resistance in COVID-19: a review

Objectives

Emerging publications indicate that diabetes predisposes patients with COVID-19 to more severe complications, which is partly attributed to inflammatory condition. In the current review, we reviewed recent published literature to provide evidence on the role of insulin resistance (IR) in diabetes, the association between diabetes and COVID-19 severity and mortality, the impact of COVID-19 infection on incident new-onset diabetes, mechanisms responsible for IR in COVID-19 patients, and the predictive value of different surrogates of IR in COVID-19.

Method

The literature search performs to find out studies that have assessed the association between IR surrogates and morbidity and mortality in patients with COVID-19.

Results

We showed that there is a bulk of evidence in support of the fact that diabetes is a potent risk factor for enhanced morbidity and mortality in COVID-19 patients. COVID-19 patients with diabetes are more prone to remarkable dysglycemia compared to those without diabetes, which is associated with an unfavourable prognosis. Furthermore, SARS-COV2 can make patients predispose to IR and diabetes via activating ISR, affecting RAAS signaling pathway, provoking inflammation, and changing the expression of PPARɣ and SREBP-1. Additionally, higher IR is associated with increased morbidity and mortality in COVID-19 patients and different surrogates of IR can be utilized as a prognostic biomarker for COVID-19 patients.

Conclusion

Different surrogates of IR can be utilized as predictors of COVID-19 complications and death.

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.

A secondary mechanism of action for triazole antifungals in Aspergillus fumigatus mediated by hmg1

Triazole antifungals function as ergosterol biosynthesis inhibitors and are frontline therapy for invasive fungal infections, such as invasive aspergillosis. The primary mechanism of action of triazoles is through the specific inhibition of a cytochrome P450 14-α-sterol demethylase enzyme, Cyp51A/B, resulting in depletion of cellular ergosterol. Here, we uncover a clinically relevant secondary mechanism of action for triazoles within the ergosterol biosynthesis pathway. We provide evidence that triazole-mediated inhibition of Cyp51A/B activity generates sterol intermediate perturbations that are likely decoded by the sterol sensing functions of HMG-CoA reductase and Insulin-Induced Gene orthologs as increased pathway activity. This, in turn, results in negative feedback regulation of HMG-CoA reductase, the rate-limiting step of sterol biosynthesis. We also provide evidence that HMG-CoA reductase sterol sensing domain mutations previously identified as generating resistance in clinical isolates of Aspergillus fumigatus partially disrupt this triazole-induced feedback. Therefore, our data point to a secondary mechanism of action for the triazoles: induction of HMG-CoA reductase negative feedback for downregulation of ergosterol biosynthesis pathway activity. Abrogation of this feedback through acquired mutations in the HMG-CoA reductase sterol sensing domain diminishes triazole antifungal activity against fungal pathogens and underpins HMG-CoA reductase-mediated resistance.

Apigenin Suppresses MED28-Mediated Cell Growth in Human Liver Cancer Cells

Flavonoids exhibit health-promoting benefits against multiple chronic diseases, including cancer. Apigenin (4',5,7-trihydroxyflavone), one flavonoid present in fruits and vegetables, is potentially applicable to chemoprevention. Despite considerable progress in the therapeutic regimen of liver cancer, its prognosis remains poor. MED28, a Mediator subunit for transcriptional activation, is implicated in the development of several types of malignancy; however, its role in liver cancer is unknown at present. In liver cancer, the AKT/mammalian target of rapamycin (mTOR) is one major pathway involved in the oncogenic process. The aim of this study is to investigate the role of apigenin and MED28 in AKT/mTOR signaling in liver cancer. We first identified a connectivity score of 92.77 between apigenin treatment and MED28 knockdown in several cancer cell lines using CLUE, a cloud-based software platform to assess connectivity among compounds and genetic perturbagens. Higher expression of MED28 predicted a poorer survival prognosis; MED28 expression in liver cancer tissue was significantly higher than that of normal tissue, and it was positively correlated with tumor stage and grade in The Cancer Genome Atlas Liver Cancer (TCGA-LIHC) data set. Knockdown of MED28 induced cell cycle arrest and suppressed the AKT/mTOR signaling in two human liver cancer cell lines, HepG2 and Huh 7, accompanied by less lipid accumulation and lower expression and nuclear localization of sterol regulatory element binding protein 1 (SREBP1). Apigenin inhibited the expression of MED28, and the effect of apigenin mimicked that of the MED28 knockdown. On the other hand, the AKT/mTOR signaling was upregulated when MED28 was overexpressed. These data indicated that MED28 was associated with the survival prognosis and the progression of liver cancer by regulating AKT/mTOR signaling and apigenin appeared to inhibit cell growth through MED28-mediated mTOR signaling, which may be applicable as an adjuvant of chemotherapy or chemoprevention in liver cancer.

A gut-derived hormone regulates cholesterol metabolism

The reciprocal coordination between cholesterol absorption in the intestine and de novo cholesterol synthesis in the liver is essential for maintaining cholesterol homeostasis, yet the mechanisms governing the opposing regulation of these processes remain poorly understood. Here, we identify a hormone, Cholesin, which is capable of inhibiting cholesterol synthesis in the liver, leading to a reduction in circulating cholesterol levels. Cholesin is encoded by a gene with a previously unknown function (C7orf50 in humans; 3110082I17Rik in mice). It is secreted from the intestine in response to cholesterol absorption and binds to GPR146, an orphan G-protein-coupled receptor, exerting antagonistic downstream effects by inhibiting PKA signaling and thereby suppressing SREBP2-controlled cholesterol synthesis in the liver. Therefore, our results demonstrate that the Cholesin-GPR146 axis mediates the inhibitory effect of intestinal cholesterol absorption on hepatic cholesterol synthesis. This discovered hormone, Cholesin, holds promise as an effective agent in combating hypercholesterolemia and atherosclerosis.

Cholesterol metabolism in tumor microenvironment: cancer hallmarks and therapeutic opportunities

Cholesterol is crucial for cell survival and growth, and dysregulation of cholesterol homeostasis has been linked to the development of cancer. The tumor microenvironment (TME) facilitates tumor cell survival and growth, and crosstalk between cholesterol metabolism and the TME contributes to tumorigenesis and tumor progression. Targeting cholesterol metabolism has demonstrated significant antitumor effects in preclinical and clinical studies. In this review, we discuss the regulatory mechanisms of cholesterol homeostasis and the impact of its dysregulation on the hallmarks of cancer. We also describe how cholesterol metabolism reprograms the TME across seven specialized microenvironments. Furthermore, we discuss the potential of targeting cholesterol metabolism as a therapeutic strategy for tumors. This approach not only exerts antitumor effects in monotherapy and combination therapy but also mitigates the adverse effects associated with conventional tumor therapy. Finally, we outline the unresolved questions and suggest potential avenues for future investigations on cholesterol metabolism in relation to cancer.

Targeting ABCG1 and SREBP-2 mediated cholesterol homeostasis ameliorates Zika virus-induced ocular pathology

Zika virus (ZIKV) infection during pregnancy causes severe neurological and ocular abnormalities in infants, yet no vaccine or antivirals are available. Our transcriptomic analysis of ZIKV-infected retinal pigment epithelial (RPE) cells revealed alterations in the cholesterol pathway. Thus, we investigated the functional roles of ATP binding cassette transporter G1 (ABCG1) and sterol response element binding protein 2 (SREPB-2), two key players in cholesterol metabolism, during ocular ZIKV infection. Our in vitro data showed that increased ABCG1 activity via liver X receptors (LXRs), reduced ZIKV replication, while ABCG1 knockdown increased replication with elevated intracellular cholesterol. Conversely, inhibiting SREBP-2 or its knockdown reduced ZIKV replication by lowering cholesterol levels. In vivo, LXR agonist or SREBP-2 inhibitor treatment mitigated ZIKV-induced chorioretinal lesions in mice, concomitant with decreased expression of inflammatory mediators and increased activation of antiviral response genes. In summary, our study identifies ABCG1's antiviral role and SREBP-2's proviral effects in ocular ZIKV infection, offering cholesterol metabolism as a potential target to develop antiviral therapies.

Activation of the PERK-CHOP signaling pathway during endoplasmic reticulum stress contributes to olanzapine-induced dyslipidemia

Olanzapine (OLZ) is a widely prescribed antipsychotic drug with a relatively ideal effect in the treatment of schizophrenia (SCZ). However, its severe metabolic side effects often deteriorate clinical therapeutic compliance and mental rehabilitation. The peripheral mechanism of OLZ-induced metabolic disorders remains abstruse for its muti-target activities. Endoplasmic reticulum (ER) stress is implicated in cellular energy metabolism and the progression of psychiatric disorders. In this study, we investigated the role of ER stress in the development of OLZ-induced dyslipidemia. A cohort of 146 SCZ patients receiving OLZ monotherapy was recruited, and blood samples and clinical data were collected at baseline, and in the 4th week, 12th week, and 24th week of the treatment. This case-control study revealed that OLZ treatment significantly elevated serum levels of endoplasmic reticulum (ER) stress markers GRP78, ATF4, and CHOP in SCZ patients with dyslipidemia. In HepG2 cells, treatment with OLZ (25, 50 μM) dose-dependently enhanced hepatic de novo lipogenesis accompanied by SREBPs activation, and simultaneously triggered ER stress. Inhibition of ER stress by tauroursodeoxycholate (TUDCA) and 4-phenyl butyric acid (4-PBA) attenuated OLZ-induced lipid dysregulation in vitro and in vivo. Moreover, we demonstrated that activation of PERK-CHOP signaling during ER stress was a major contributor to OLZ-triggered abnormal lipid metabolism in the liver, suggesting that PERK could be a potential target for ameliorating the development of OLZ-mediated lipid dysfunction. Taken together, ER stress inhibitors could be a potentially effective intervention against OLZ-induced dyslipidemia in SCZ.

Sensing and regulation of long-chain polyunsaturated fatty acids pool in marine mollusks: Characterization of UBXD8 from the razor clam Sinonovacula constricta

The razor clam Sinonovacula constricta is known for its richness in long-chain polyunsaturated fatty acids (LC-PUFA, C ≥ 20). Previously, we demonstrated that it possesses a complete LC-PUFA biosynthetic pathway. However, the mechanisms by which it senses the LC-PUFA pool to regulate their biosynthesis remain unclear. Here, we presented the LC-PUFA sensor UBXD8 as a critical molecule in this intriguing process. The S. constricta UBXD8 (ScUBXD8) shared all characteristic features of its mammalian counterpart and exhibited high mRNA levels in digestive tissues, suggesting its functional role in this bivalve species. By purification of ScUBXD8 protein in vitro, we discovered its ability to sense unsaturated fatty acids (UFA, C ≥ 14) but not saturated ones, as evidenced by polymerization detection. Furthermore, the intensity of ScUBXD8 polymerization increased progressively with longer acyl chain lengths, greater unsaturation degrees, and higher UFA concentrations. Exceptionally, for those located at the same node in LC-PUFA biosynthetic pathway, ScUBXD8 displayed a stronger sensitivity to n-6 UFA compared to n-3 UFA. These results suggested a critical role for ScUBXD8 in balancing fatty acids composition and ratio of n-6/n-3 UFA in S. constricta. Moreover, the UAS domain was confirmed essential for ScUBXD8 polymerization. Through knockdown of ScUbxd8 gene in vivo, there were significant shifts in expression patterns of genes related to LC-PUFA biosynthesis, concurrently influencing fatty acids compositions. These results suggested that ScUBXD8 likely plays a regulatory role in LC-PUFA biosynthesis, possibly through the INSIG-SREBP pathway. Collectively, this study proposed that S. constricta might maintain LC-PUFA homeostasis through UBXD8 to regulate their biosynthesis.

KRAS mutation-selective requirement for ACSS2 in colorectal adenoma formation

Oncogenic KRAS mutations are prevalent in colorectal cancer (CRC) and are associated with poor prognosis and resistance to therapy. There is a substantial diversity of KRAS mutant alleles observed in CRC. Emerging clinical and experimental analysis of common KRAS mutations suggest that each mutation differently influences the clinical properties of a disease and response to therapy. Although there is some evidence to suggest biological differences between mutant KRAS alleles, these are yet to be fully elucidated. One approach to study allelic variation involves the use of isogenic cell lines that express different endogenous Kras mutants. Here, we generated Kras isogenic Apc-/- mouse colon epithelial cell lines using CRISPR-driven genome editing by altering the original G12D Kras allele to G12V, G12R, or G13D. We utilized these cell lines to perform transcriptomic and proteomic analysis to compare different signaling properties between these mutants. Both screens indicate significant differences in pathways relating to cholesterol and lipid regulation that we validated with targeted metabolomic measurements and isotope tracing. We found that these processes are upregulated in G12V lines through increased expression of nuclear SREBP1 and higher activation of mTORC1. G12V cells showed higher expression of ACSS2 and ACSS2 inhibition sensitized G12V cells to MEK inhibition. Finally, we found that ACSS2 plays a crucial role early in the development of G12V mutant tumors, in contrast to G12D mutant tumors. These observations highlight differences between KRAS mutant cell lines in their signaling properties. Further exploration of these pathways may prove to be valuable for understanding how specific KRAS mutants function, and identification of novel therapeutic opportunities in CRC.

PEDV inhibits HNRNPA3 expression by miR-218-5p to enhance cellular lipid accumulation and promote viral replication

Porcine epidemic diarrhea virus (PEDV) requires complete dependence on the metabolic system of the host cell to complete its life cycle. There is a strong link between efficient viral replication and cellular lipid synthesis. However, the mechanism by which PEDV interacts with host cells to hijack cellular lipid metabolism to promote its replication remains unclear. In this study, PEDV infection significantly enhanced the expression of lipid synthesis-related genes and increased cellular lipid accumulation. Furthermore, using liquid chromatography-tandem mass spectrometry, we identified heterogeneous nuclear ribonucleoprotein A3 (HNRNPA3) as the interacting molecule of PEDV NSP9. We demonstrated that the expression of HNRNPA3 was downregulated by PEDV-induced miR-218-5p through targeting its 3' untranslated region. Interestingly, knocking down HNRNPA3 facilitated the PEDV replication by promoting cellular lipid synthesis. We next found that the knockdown of HNRNPA3 potentiated the transcriptional activity of sterol regulatory element-binding transcription factor 1 (SREBF1) through zinc finger protein 135 (ZNF135) as well as PI3K/AKT and JNK signaling pathways. In summary, we propose a model in which PEDV downregulates HNRNPA3 expression to promote the expression and activation of SREBF1 and increase cellular lipid accumulation, providing a novel mechanism by which PEDV interacts with the host to utilize cellular lipid metabolism to promote its replication.IMPORTANCEAs the major components and structural basis of the viral replication complexes of positive-stranded RNA viruses, lipids play an essential role in viral replication. However, how PEDV manipulates host cell lipid metabolism to promote viral replication by interacting with cell proteins remains poorly understood. Here, we found that SREBF1 promotes cellular lipid synthesis, which is essential for PEDV replication. Moreover, HNRNPA3 negatively regulates SREBF1 activation and specifically reduces lipid accumulation, ultimately inhibiting PEDV dsRNA synthesis. Our study provides new insight into the mechanisms by which PEDV hijacks cell lipid metabolism to benefit viral replication, which can offer a potential target for therapeutics against PEDV infection.