Lipolysis: cellular mechanisms for lipid mobilization from fat stores

A lipid droplet-targeted probe for imaging of lipid metabolism disorders during mitochondrial myopathy

Lipid metabolism is closely related to various biological processes in cells. The accumulation of Lipid droplets (LDs) is a typical manifestation of certain metabolic diseases, such as mitochondrial myopathy, which shows a significant increase in LDs. The accumulation of LDs can exacerbate the progression of disease, and lysosomes selectively degrade LDs to cope with this phenomenon. Visualizing lipid metabolism disorders and the interaction between LDs and other organelles is of great significance for the diagnosis and understanding of various physiological processes within cells in diseases. In this work, we synthesized two novel LD fluorescent probes and screened the best PDM, which exhibited stable fluorescence performance and strong photobleaching resistance in complex environments. The dynamics of intracellular LDs were tracked using PDM, and abnormal lipid metabolism within mitochondrial myopathy cells was visualized. This provides new tools and perspectives for studying LD dynamics and diagnosing mitochondrial myopathy.

Integrative metabolomics and microbiomics analysis reveals distinctive microbiota-metabolites interactions in gastric carcinogenesis

Gastric microbiota and metabolites may interact and play collaborative roles in the carcinogenesis process. This study aims to investigate differential metabolites and microbes, as well as the possible roles of microbe-metabolite interactions in gastric cancer (GC) development. Targeted metabolomics assays and 16S rRNA sequencing were performed to compare metabolic and microbial profiles in gastric tissues from subjects with superficial gastritis/chronic atrophic gastritis (SG/CAG), intestinal metaplasia/low-grade intraepithelial neoplasia (IM/LGIN) and GC. Significant differences were found in metabolic and microbial profiles between the GC and SG/CAG or IM/LGIN groups, respectively (all p < .05). By comparing GC with the other lesions, 69 differential metabolites mainly comprised triglycerides and phosphatidylcholines, and 21 differential microbes included Peptostreptococcus, Lactobacillus, Dialister, Helicobacter pylori, and Streptococcus anginosus (all p < .05). The altered metabolites and microbes in GC were both significantly enriched in the glycerophospholipid metabolism pathway, in which the predicted down-regulation of phospholipase C (plc) and up-regulation of 1-acyl-sn-glycerol-3-phosphate acyltransferase (plsC) by microbiota may affect phosphatidylcholine hydrolysis and triglyceride biosynthesis modules. More and stronger microbe-metabolite correlations in GC compared to the other lesion group further supported the potential microbial regulations to the important metabolites in gastric carcinogenesis, such as Lactobacillus and phosphatidylcholines (.32 ≤ r ≤ .57, all p < .05), Peptostreptococcus (.36 ≤ r ≤ .60, all p < .05) or Dialister (.36 ≤ r ≤ .62, all p < .05) and triglycerides. We simultaneously identified differential metabolites and microbes and their altered correlations between GC and gastric lesions. The main GC-associated phosphatidylcholines and triglycerides may be affected by gastric microbes, which provides new perspectives on the microbiota-metabolite interactions during the development of GC.

Genome-wide analysis reveals the evolutionary history of TAG intracellular lipases and their roles in different molting stages of Decapods

Intracellular lipases can be broadly divided into two categories: neutral lipases and acid lipases. Adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and monoacylglycerol lipase (MAGL) are three key neutral lipases responsible for the hydrolysis of triacylglycerol (TAG) in lipid droplets (LDs). Although these three TAG intracellular lipase genes have been identified and characterized in multiple model species, their evolutionary history remains largely unknown. For the TAG intracellular lipase genes in Decapoda, there is also a large knowledge gap. Thus, in this study, we performed a genome-wide identification and investigation of TAG intracellular lipase genes in Decapoda and outgroups, analyzing their phylogenetics, structural features, conserved motifs, and expression patterns. In total, 22 ATGL genes, 23 HSL genes and 21 MAGL genes were identified in 17 selected species. HSL is the oldest and most conserved gene to exist in any species. Furthermore, RNA-seq analysis was conducted on two representative Decapod species, Chinese mitten crab (Eriocheir sinensis) and swimming crab (Portunus trituberculatus), which represent freshwater and marine environments, respectively. The analysis revealed a positive correlation between the expression levels of TAG intracellular lipase genes and the energy demand during different molting stages. Overall, the results of this study provide valuable insights into the evolutionary history of TAG intracellular lipase genes, which could enhance our understanding for the role of these genes during key physiological processes of Decapods.

Features, functions, and associated diseases of visceral and ectopic fat: a comprehensive review

Obesity is a complex, chronic, and recurrent disease marked by abnormal or excessive fat accumulation that poses significant health risks. The distribution of body fat, especially ectopic fat deposition, plays a crucial role in the development of chronic metabolic diseases. Under normal conditions, fatty acids are primarily stored in subcutaneous adipose tissue; however, excessive intake can lead to fat accumulation in visceral adipose tissue and ectopic sites, including the pancreas, heart, and muscle. This redistribution is associated with disruptions in energy metabolism, inflammation, and insulin resistance, impairing organ function and raising the risk of cardiovascular disease, diabetes, and fatty liver. This review explores the roles of visceral and ectopic fat in the development of insulin resistance and related diseases such as type 2 diabetes and metabolic dysfunction-associated steatotic liver disease. Specifically, we examine the structure and characteristics of different fat types, their associations with disease, and the underlying pathogenic mechanisms. Future strategies for managing obesity-related diseases may include lifestyle modifications, surgical interventions, and emerging medications that target lipid metabolism and energy regulation, aiming to improve patient outcomes.

PNPLA3 gene variation modulates diet-induced improvement in liver lipid content in type 2 diabetes

BACKGROUND&AIMS

Lifestyle-induced weight reduction remains crucial for managing type 2 diabetes and steatotic liver disease, but its effectiveness varies. We postulated that the G allele in the rs738409 single nucleotide polymorphism within patatin-like phospholipase domain-containing protein 3 (PNPLA3), which associates with metabolic dysfunction-associated steatotic liver disease, also modulates diet-related metabolic effects.

METHODS

Participants with type 2 diabetes were randomized to 8-week hypocaloric diets (energy intake: -1,256 kJ/d of, <30 kcal% fat): high in cereal fiber and coffee excluding red meat (HF-RM + C; n = 16), or low in cereal fiber, devoid of coffee, but high in red meat (LF + RM-C; n = 15). Whole-body insulin sensitivity (M value) was assessed using [2H]glucose and hyperinsulinemic-normoglycemic clamps, hepatic lipid content (HCL) and body fat volumes by magnetic resonance spectroscopy/imaging before and after intervention.

RESULTS

Despite comparable weight loss, HCL decreased more in non-carriers (-65 %) than in G-allele carriers (-36 %) upon HF-RM + C diet (both p < 0.05 vs baseline and between groups), but only among non-carriers (-46 %, p < 0.05 vs baseline) upon LF + RM-C. Upon HF-RM + C diet, increase in insulin sensitivity was not different between carriers (+27 % p = 0.051 from baseline) and non-carriers (+21 %, p = 0.032 from baseline), p > 0.05 for between-group comparison. Upon LF + RM-C diet, both groups equally improved their whole-body insulin sensitivity (+42 % for non-carriers and +37 % for carriers, p < 0.05 vs baseline). Upon HF-RM + C diet, non-carriers decreased circulating interleukin-18 from baseline by -31 %, whereas, upon LF + RM-C diet, non-carriers decreased circulating anti-inflammatory interleukin-1 receptor antagonist levels by 14 % (both p < 0.05 vs baseline).

CONCLUSIONS

Humans with the PNPLA3 G-allele show modified dietary-induced effects on steatotic liver disease in type 2 diabetes despite body weight reduction. Registration at Clinicaltrials.gov, Identifier number: NCT01409330.

Developing a polarity-specialized TICT fluorescent probe for wash-free and long-term monitoring lipid droplets dynamics

Lipid droplets (LDs) are dynamic and multifunctional organelles that play a crucial role in energy storage, metabolism and lipid signaling. Monitoring the dynamics of LDs is essential for understanding their functions. Twisted intramolecular charge transfer (TICT)-based fluorescent molecules have been widely utilized for LD imaging. However, conventional TICT dyes exhibit sensitivity to both polarity and viscosity, which results in unclear sensing mechanisms for LDs. Additionally, current LD imaging techniques face challenges such as complex washing procedures and limited long-term imaging capabilities. This study presented a far-red coumarin framework designed to modulate the TICT-ICT equilibrium, resulting in the development of two fluorophores that exhibit specialized sensitivity to either polarity or viscosity. The findings suggested that sensitivity to polarity is a crucial factor for LD imaging, as high signal-to-noise ratios (SNR) enable wash-free imaging, while suitable lipophilicity supports long-term imaging. This polarity-specialized TICT probe had the potential to revolutionize LD imaging, facilitating wash-free and extended studies of LD dynamic behaviors and functions during lipolysis.

Dietary protein deficiency exacerbates perfluorohexane sulfonate (PFHxS)-induced reproductive abnormalities and metabolic disruptions in female rats

Perfluorohexane sulfonate (PFHxS) is a persistent environmental contaminant linked with several health implications. Humans are exposed to PFHxS mainly through ingestion. Studies reported that a diet deficient in essential nutrients may have confounding effect on toxicity outcome of chemicals. We evaluated the potential impact of PFHxS exposure on reproductive damage in animals maintained on the diet deficient in protein. Female Wistar rats (n=6) were divided as controls and treatment groups (5 ppm and 25 ppm PFHxS, protein deficient, protein deficient +5 ppm PFHxS and protein deficient +25 ppm PFHxS). Chronic PFHxS exposure disrupted the estrous cycle with an increased duration of the diestrus stage at 25 ppm and protein deficient +25 ppm PFHxS showing 55.56% and 78.77% disorder, respectively. There was a significant elevation (P<0.01) in LH/FSH ratio and reduction in testosterone (P<0.01), estradiol (P<0.01), and progesterone (P<0.001) in protein deficient +25 ppm PFHxS group. A high order of increase in lipid profile parameters was found in protein deficient +25 ppm PFHxS group. However, high-density lipoprotein decreased in this group. Protein deficient +25 ppm PFHxS group animals also revealed high level of oxidative stress. Histopathological findings revealed the presence of cystic follicles and theca cell degeneration in ovaries in protein deficient +25 ppm PFHxS group with a significant decreased (P<0.01) in the myometrium and endometrial area of uterus. The combined effect of protein deficiency and PFHxS exposure caused a greater reprotoxicity compared to either factor alone implying an increased vulnerability of reproductive function in malnourished populations to environmental contaminants.

Targeting B7-H3 inhibition-induced activation of fatty acid synthesis boosts anti-B7-H3 immunotherapy in triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is the most malignant breast cancer, highlighting the need for effective immunotherapeutic targets. The immune checkpoint molecule B7-H3 has recently gained attention as a promising therapeutic target due to its pivotal role in promoting tumorigenesis and cancer progression. However, the therapeutic impact of B7-H3 inhibitors (B7-H3i) remains unclear.

METHODS

Transcriptomic and metabolomic analyses were conducted to explore the underlying mechanisms of B7-H3 inhibition in TNBC. The therapeutic efficacy of the combined treatment strategy was substantiated through comprehensive phenotypic assays conducted in vitro and validated in vivo using animal models.

RESULTS

B7-H3 blockade induces a "primed for death" stress state in cancer cells, leading to distinct alterations in metabolic pathways. Specifically, B7-H3 knockdown activated the AKT signaling pathway and upregulated sterol regulatory element-binding protein 1 (SREBP1), which in turn elevated FASN expression. The simultaneous inhibition of both B7-H3 and FASN more effectively attenuated the malignant progression of TNBC.

CONCLUSIONS

Our findings propose an "immune attack-metabolic compensation" dynamic model and suggest the feasibility of a dual-targeting strategy that concurrently inhibits both B7-H3 and FASN to enhance therapeutic efficacy in TNBC patients.

Integration of Conjugated Linoleic Acid-Producing Probiotic Strains Having Anti-adipogenic Properties with Honey and Oyster Mushrooms for the Formulation of Non-dairy Probiotic Beverage

Conjugated linoleic acid (CLA) has been linked to various health benefits, including anti-cancer, anti-diabetic, and anti-obesity effects. Obesity, marked by abnormal fat deposition, increases the risk of metabolic disorders such as cardiovascular diseases and type-2 diabetes. Natural anti-adipogenic modulators with insulin sensitivity are one of the approaches to address the issue. In the present study, four distinct CLA-producing probiotic strains (Lacticaseibacillus paracasei LUL:01, Latilactobacillus curvatus LGM:16, Lactiplantibacillus paraplantarum LRJ1:09, and Enterococcus faecalis LJM:05) were assessed in vitro for their potential anti-adipogenic properties using 3T3-L1 preadipocytes. Out of four strains, LGM:16 inhibited lipid accumulation (100.27%), reduced intracellular triglyceride content (168.42, 168.16, and 153.66 mg/dL in a dose-dependent manner), and enhanced insulin sensitivity (32.23%) by increasing glucose uptake. Quantitative reverse-transcription polymerase chain reaction revealed the expression genes (PPARγ, C/EBPα, and GLUT-4) in LGM:16 strain. Consequently, LGM: 16 was used to develop a non-dairy probiotic formulation incorporating honey and Pleurotus ostreatus mushroom, ensuring a probiotic count above the minimum recommended level of 6 Log10 CFU/mL. Further, response surface methodology optimized probiotic beverage formulation to achieve favorable nutritional, good sensory profile, antioxidant, and anti-obesity activity, making it a promising candidate for health benefits.

Tumor-derived arachidonic acid reprograms neutrophils to promote immune suppression and therapy resistance in triple-negative breast cancer

The combination of immune checkpoint blockade and chemotherapies is the standard of care for triple-negative breast cancer (TNBC). However, initially, responsive tumors can still develop recurrences, suggesting acquired resistance mechanisms that remain poorly understood. Herein, we discover that TNBC cells surviving anti-programmed cell death protein-1 (anti-PD-1) and chemotherapy treatment accumulate neutral lipids. Disrupting lipid droplet formation in cancer cells reverses resistance and mitigates the immunosuppressive microenvironment. Single-cell RNA sequencing reveals a subset of neutrophils exhibiting a lipid-laden phenotype similar to adjacent tumor cells. Mechanistically, tumor-derived extracellular vesicles carrying lipids, including arachidonic acid (AA), mediate neutrophil reprogramming. Blocking dietary intake of omega-6 fatty acids or inhibiting fatty acid elongation for AA synthesis restores anti-tumor immunity and re-sensitizes the resistant tumors to anti-PD-1 and chemotherapy treatment. In human patients, AA metabolism-related pathways correlates with neutrophil enrichment. Overall, we demonstrate how lipid accumulation in TNBC cells leads to immune suppression and therapy resistance.

Releasing stored lipids to fuel migration and reproduction in the eel, Anguilla australis-a role for 11-ketotestosterone?

Migrating freshwater eels depend on the mobilisation of stored lipids to successfully arrive at their distant spawning locations. As 11-ketotestosterone (11KT) can increase the lipid-transporting capability and enhance gonadal lipid uptake in eel, we hypothesized that this androgen would also regulate lipid mobilisation from its stores. To address this hypothesis, we first sampled residential (yellow) and migrating (silver) short-finned eels from the wild and evaluated the expression of 24 genes encoding lipolytic or lipogenic enzymes, as well as those encoding both nuclear androgen receptors, by NanoString analysis. Plasma 11KT levels in silver eels were dramatically increased, and mRNA levels of more than half of all target genes were higher in silver eel muscle; none of the target genes was significantly downregulated. Gene expression profiles in white muscle from wild-caught eels were subsequently compared with those from yellow and silver eels subjected to implantation with sustained-release implants containing 11KT. Several weeks of exposure resulted in plasma levels of 11KT that resembled those of wild-caught eels and resulted in a dose-dependent increase in gonadosomatic and hepatosomatic index; however, target gene expression profiles in muscle were barely affected. We conclude that lipid physiology in white muscle of silver eels is notably different from that in yellow eels, and that 11KT is not responsible for the differentially expressed gene profile between yellow and silver short-finned eels.

Cytoskeleton regulates lipid droplet fusion and lipid storage by controlling lipid droplet movement

Lipid droplets (LDs) are highly dynamic organelles that maintain cellular lipid homeostasis through size and number control. In adipose tissue, CIDEC plays a crucial role in LD fusion and lipid homeostasis. However, the regulatory factors and mechanisms of LD fusion remain largely unknown. Here, we established a high-throughput LD phenotypic screen on a compound library consisting of 2010 small molecules, and identified 11 cytoskeleton inhibitors that negatively regulate LD size. Using specific inhibitors against each of the three types of cytoskeleton, our data showed that the disruption of microtubules and microfilaments but not intermediate filaments limits CIDEC-mediated LD fusion and growth by reducing LD movement and LD-LD contact. The collective effect of microtubule inhibitors results in a small LD phenotype which favors lipolysis upon activation of cAMP-PKA pathway in adipocytes. Our findings demonstrate that cytoskeleton is involved in the process of LD fusion and growth, indicating their role in lipid storage metabolism. One-Sentence Summary: Cytoskeleton regulates lipid droplet fusion and lipid storage.

Association of the non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) with COPD prevalence and all-cause mortality: a population-based study based on NHANES 2007-2016

Background

The non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) plays a potential role in metabolic and cardiovascular diseases. However, its association with chronic obstructive pulmonary disease (COPD) is not well-defined. Here, we aim to investigate the potential association of NHHR with both the prevalence of COPD and all-cause mortality among individuals with COPD.

Methods

This population-based NHANES (2007-2016) study utilized weighted statistical analyses. Multivariable logistic regression assessed the NHHR-COPD prevalence association, with restricted cubic spline (RCS) testing for non-linearity. The association between NHHR and all-cause mortality in COPD was evaluated using Cox proportional hazards models and Kaplan-Meier, with RCS testing for non-linearity. Subgroup and sensitivity analyses confirmed the findings' reliability.

Results

This study included 6349 participants, of whom 1271 were diagnosed with COPD. Participants in the highest NHHR tertile demonstrated 62% higher odds of COPD prevalence compared to those in the lowest tertile (OR = 1.62, 95% CI:1.11-2.39, P = 0.017). Results from RCS analysis indicated a nonlinear relationship between NHHR and the prevalence of COPD (P for nonlinear = 0.007), with the curve demonstrating an inverted L-shape. Over an average follow-up period of 93 months, 320 participants with COPD died. In the weighted Kaplan-Meier survival analysis, participants with COPD in the lower NHHR tertile demonstrated greater cumulative probability of all-cause mortality compared to higher tertiles (P < 0.001). Weighted multivariable Cox regression models revealed an inverse association between NHHR levels and COPD all-cause mortality, with the highest NHHR tertile showing 11% lower likelihood of COPD all-cause mortality relative to the lowest tertile (HR = 0.89, 95% CI:0.80-0.99, P = 0.027). In addition, RCS analysis demonstrated a significant negative linear association between NHHR levels and all-cause mortality in COPD patients (P for nonlinear = 0.081). Subgroup and sensitivity analyses further confirmed the associations of NHHR on both morbidity and all-cause mortality.

Conclusion

Higher NHHR levels were associated with increased COPD prevalence yet inversely correlated with all-cause mortality in COPD patients. These paradoxical associations underscore the need for COPD-specific lipid management strategies that balance disease progression and mortality risks.

TRIM56 Promotes White Adipose Tissue Browning to Attenuate Obesity by Degrading TLE3

In mammals, the activation of thermogenic adipocytes, such as beige and brown adipocytes, can significantly increase overall energy expenditure, offering a promising strategy to combat metabolic diseases. Despite its considerable potential, the regulatory mechanisms governing this activation remain largely elusive. This study bridges this gap by elucidating that tripartite motif 56 (TRIM56), an E3 ubiquitin ligase, is upregulated in response to cold stimuli, thereby promoting the recruitment of beige adipocytes. Notably, the overexpression of TRIM56 in adipocytes is shown to help mice maintain a core temperature under cold conditions, as well as confer protection against diet-induced obesity. Mechanistically, TRIM56 facilitates the degradation of the transducin-like enhancer protein 3 (TLE3) protein by promoting its K48-linked ubiquitination, which subsequently triggers the activation of thermogenic genes in subcutaneousl white adipose tissue and improved the metabolic profiles. These findings unveil a novel function for TRIM56 in adipocyte browning, suggesting its potential as a therapeutic target for the treatment of metabolic disorders.

Knockdown of the Clock gene in the liver aggravates MASLD in mice via inhibiting lipophagy

The increased global prevalence of metabolic dysfunction-associated steatohepatitis (MASLD) has been closely associated with chronic disorders of the circadian clock. Herein, we investigate the role of Clock, a core circadian gene, in the pathogenesis of MASLD. Wild-type (WT) and liver-specific Clock knockdown (Clock-KD) mice were fed a Western diet for 20 weeks to induce MASLD. A cellular MASLD model was established by treating AML12 cells with free fatty acids and the effects of Clock knockdown were examined following transfection with Clock siRNA. Increased lipid deposition and more severe steatohepatitis and fibrosis were observed in the livers of Western diet-fed but not normal chow diet-fed Clock-KD mice after 20 weeks compared to WT mice. Moreover, the Clock gene was found to be significantly downregulated in WT MASLD mice. The Clock gene was shown to regulate the expression of lipophagy-related proteins (LC3B, P62, RAB7, and PLIN2) in vivo and in vitro. Knockdown of Clock was found to inhibit lipophagy resulting in increased accumulation of lipid droplets in the mouse liver and AML12 cells. Interestingly, the CLOCK protein was shown to interact with P62. However, knockdown of the Clock gene did not promote transcription of the P62 gene but suppressed degradation of the P62 protein during lipophagy in AML12 cells. The hepatic Clock gene regulates lipophagy and affects lipid droplet deposition in liver cells, and thus plays a critical role in the development of MASLD induced by a Western diet.

Exercise-induced anti-obesity effects in male mice generated by a FOXO1-KLF10 reinforcing loop promoting adipose lipolysis

Exercise combats obesity and metabolic disorders, but the underlying mechanism is incompletely understood. KLF10, a transcription factor involved in various biological processes, has an undefined role in adipose tissue and obesity. Here, we show that exercise facilitates adipocyte-derived KLF10 expression via SIRT1/FOXO1 pathway. Adipocyte-specific knockout of KLF10 blunts exercise-promoted white adipose browning, energy expenditure, fat loss, glucose tolerance in diet-induced obese male mice. Conversely, adipocyte-specific transgenic expression of KLF10 in male mice enhanced the above metabolic profits induced by exercise. Mechanistically, KLF10 interacts with FOXO1 and facilitates the recruitment of KDM4A to form a ternary complex on the promoter regions of Pnpla2 and Lipe genes to promote these key lipolytic genes expression by demethylating H3K9me3 on their promoters, which facilitates lipolysis to defend against obesity in male mice. As a downstream effector responding to exercise, adipose KLF10 could act as a potential target in the fight against obesity.

Physiological Fatty Acid-Stimulated Insulin Secretion and Redox Signaling Versus Lipotoxicity

Significance: Type 2 diabetes as a world-wide epidemic is characterized by the insulin resistance concomitant to a gradual impairment of β-cell mass and function (prominently declining insulin secretion) with dysregulated fatty acids (FAs) and lipids, all involved in multiple pathological development. Recent Advances: Recently, redox signaling was recognized to be essential for insulin secretion stimulated with glucose (GSIS), branched-chain keto-acids, and FAs. FA-stimulated insulin secretion (FASIS) is a normal physiological event upon postprandial incoming chylomicrons. This contrasts with the frequent lipotoxicity observed in rodents. Critical Issues: Overfeeding causes FASIS to overlap with GSIS providing repeating hyperinsulinemia, initiates prediabetic states by lipotoxic effects and low-grade inflammation. In contrast the protective effects of lipid droplets in human β-cells counteract excessive lipids. Insulin by FASIS allows FATP1 recruitment into adipocyte plasma membranes when postprandial chylomicrons come late at already low glycemia. Future Directions: Impaired states of pancreatic β-cells and peripheral organs at prediabetes and type 2 diabetes should be revealed, including the inter-organ crosstalk by extracellular vesicles. Details of FA/lipid molecular physiology are yet to be uncovered, such as complex phenomena of FA uptake into cells, postabsorptive inactivity of G-protein-coupled receptor 40, carnitine carrier substrate specificity, the role of carnitine-O-acetyltransferase in β-cells, and lipid droplet interactions with mitochondria. Antioxid. Redox Signal. 42, 566-622.

Inhibition of ATGL alleviates MASH via impaired PPARα signalling that favours hydrophilic bile acid composition in mice

BACKGROUND & AIMS

Adipose triglyceride lipase (ATGL) is an attractive therapeutic target in insulin resistance and metabolic dysfunction-associated steatotic liver disease (MASLD). This study investigated the effects of pharmacological ATGL inhibition on the development of metabolic dysfunction-associated steatohepatitis (MASH) and fibrosis in mice.

METHODS

Streptozotocin-injected male mice were fed a high-fat diet to induce MASH. Mice receiving the ATGL inhibitor atglistatin (ATGLi) were compared to controls using liver histology, lipidomics, metabolomics, 16s rRNA, and RNA sequencing. Human ileal organoids, HepG2 cells, and Caco2 cells treated with the human ATGL inhibitor NG-497, HepG2 ATGL knockdown cells, gel-shift, and luciferase assays were analysed for mechanistic insights. We validated the benefits of ATGLi on steatohepatitis and fibrosis in a low-methionine choline-deficient mouse model.

RESULTS

ATGLi improved serum liver enzymes, hepatic lipid content, and histological liver injury. Mechanistically, ATGLi attenuated PPARα signalling, favouring hydrophilic bile acid (BA) synthesis with increased Cyp7a1, Cyp27a1, Cyp2c70, and reduced Cyp8b1 expression. Additionally, reduced intestinal Cd36 and Abca1, along with increased Abcg5 expression, were consistent with reduced levels of hepatic triacylglycerol species containing polyunsaturated fatty acids, like linoleic acid, as well as reduced cholesterol levels in the liver and plasma. Similar changes in gene expression associated with PPARα signalling and intestinal lipid transport were observed in ileal organoids treated with NG-497. Furthermore, HepG2 ATGL knockdown cells revealed reduced expression of PPARα target genes and upregulation of genes involved in hydrophilic BA synthesis, consistent with reduced PPARα binding and luciferase activity in the presence of the ATGL inhibitors.

CONCLUSIONS

Inhibition of ATGL attenuates PPARα signalling, translating into hydrophilic BA composition, interfering with dietary lipid absorption, and improving metabolic disturbances. Validation with NG-497 opens a new therapeutic perspective for MASLD.

IMPACT AND IMPLICATIONS

Despite the recent approval of drugs novel mechanistic insights and pathophysiology-oriented therapeutic options for MASLD (metabolic dysfunction-associated steatotic liver disease) are still urgently needed. Herein, we show that pharmacological inhibition of ATGL, the key enzyme in lipid hydrolysis, using atglistatin (ATGLi), improves MASH (metabolic dysfunction-associated steatohepatitis), fibrosis, and key features of metabolic dysfunction in mouse models of MASH and liver fibrosis. Mechanistically, we demonstrated that attenuation of PPARα signalling in the liver and gut favours hydrophilic bile acid composition, ultimately interfering with dietary lipid absorption. One of the drawbacks of ATGLi is its lack of efficacy against human ATGL, thus limiting its clinical applicability. Against this backdrop, we could show that ATGL inhibition using the human inhibitor NG-497 in human primary ileum-derived organoids, Caco2 cells, and HepG2 cells translated into therapeutic mechanisms similar to ATGLi. Collectively, these findings reveal a possible new avenue for MASLD treatment.

FGF1 alleviates polystyrene nanoplastics-induced neuroinflammation through the suppression of lipophagy

Global contamination with nanoplastics (NPs) has raised public concern regarding their adverse effects on human health. However, little is known about the toxic effects of NPs on the nervous system. This study explored the neurotoxicity of polystyrene nanoplastics (PS-NPs) under the exposure model in vitro and in vivo. The results showed that environmentally relevant PS-NPs exposure activated lipophagy-related lipolysis. This activation promoted the production of lipid inflammatory mediators 2-arachidonoylglycerol (2-AG) and prostaglandin E2 (PGE2), thereby driving neuroinflammation in vitro. RNA sequencing revealed that fibroblast growth factor (FGF1) was negatively associated with the activation of lipophagy. Exogenous treatment with FGF1 inhibited PS-NPs-induced neuroinflammation and lipid accumulation in vitro and in vivo via the suppression of lipophagy. In addition, exogenous treatment with FGF1 alleviated PS-NPs-induced learning and memory deficits and neuropathological injury in mice. Our results provided new insights into the neurotoxicity effects and mechanisms of PS-NPs. Meanwhile, we found that FGF1 is a potential neuroprotective factor against PS-NPs-induced neurological injury by remodeling lipid metabolism in the central nervous system.

Adipocyte-derived shed Syndecan-4 suppresses lipolysis contributing to impaired adipose tissue browning and adaptive thermogenesis

Lipolysis in white adipose tissue (WAT) provides fatty acids as energy substrates for thermogenesis to increase energy expenditure. Syndecan-4 (Sdc4) is a transmembrane proteoglycan bearing heparan sulfate chains. Although single nucleotide polymorphisms (SNPs) of the Sdc4 gene have been identified linking to metabolic syndromes, its specific function in adipose tissue remains obscure. Here, we show that Sdc4 serves as a regulator of lipid metabolism and adaptive thermogenesis. Sdc4 expression and shedding are elevated in the white adipose tissue (WAT) of diet-induced obese mice. Adipocyte-specific deletion of Sdc4 promotes lipolysis and WAT browning, thereby raising whole-body energy expenditure to protect against diet-induced obesity. Mechanistically, fibroblast growth factor 2 (FGF2) is a paracrine factor that maintains energy homeostasis. Elevated shed Sdc4 concentrates and delivers FGF2 to fibroblast growth factor receptor 1 (FGFR1) on adipocytes, which in turn suppresses lipolysis by reducing hormone-sensitive lipase (HSL) activity, thus exaggerating adipose tissue dysfunction upon high-fat diet induction. Sdc4-deficient adipocytes show higher lipolytic and thermogenic capacity by enhancing HSL phosphorylation and UCP1 expression. Overall, our study reveals that adipocyte-derived shed Sdc4 is a novel suppressor of lipolysis, contributing to decreased energy expenditure, thus exaggerating obesity. Targeting shed Sdc4 is a potential therapeutic strategy for obesity.

ABHD5 regulates midgut-specific lipid homeostasis in Bombyx mori

Lipids are an important energy source and are utilized as substrates for various physiological processes in insects. Comparative gene identification 58 (CGI-58), also known as α/β hydrolase domain-containing 5 (ABHD5), is a highly conserved and multifunctional gene involved in regulating lipid metabolism and cellular energy balance in many organisms. However, the biological functions of ABHD5 in insects are poorly understood. In the current study, we describe the identification and characterization of the ABHD5 gene in the lepidopteran model insect, Bombyx mori. The tissue expression profile investigated using quantitative reverse transcription polymerase chain reaction (RT-qPCR) reveals that BmABHD5 is widely expressed in all tissues, with particularly high levels found in the midgut and testis. A binary transgenic CRISPR/Cas9 system was employed to conduct a functional analysis of BmABHD5, with the mutation of BmABHD5 leading to the dysregulation of lipid metabolism and excessive lipid accumulation in the larval midgut. Histological and physiological analysis further reveals a significant accumulation of lipid droplets in the midgut of mutant larvae. RNA-seq and RT-qPCR analysis showed that genes related to metabolic pathways were significantly affected by the absence of BmABHD5. Altogether, our data prove that BmABHD5 plays an important role in regulating tissue-specific lipid metabolism in the silkworm midgut.

Transforming Growth Factor β1 Protects Against Ischemic Demyelination via Regulating Microglial Lipid Metabolism Pathway

BACKGROUND

Chronic cerebral hypoperfusion-induced white matter lesions are an important cause of vascular cognitive impairment in aging life. TGF-β1 (transforming growth factor β1) is widely recognized as a multifunctional cytokine participating in numerous pathophysiological processes in the central nervous system. In this study, we aimed to evaluate the neuroprotective potentials of TGF-β1 in ischemic white matter lesions.

METHODS

A mouse model of bilateral common carotid artery stenosis was established to imitate the ischemic white matter lesions. The agonist of the TGF-β1 pathway was continuously applied via intraperitoneal injection. The Morris water maze test and gait analysis system were used to assess the cognitive and gait disorders in modeling mice. The Luxol fast blue staining, immunofluorescence, and electron microscopy were conducted to determine the severity of demyelinating lesions, microglial activation, and dysfunction of the autophagy-lysosomal pathway in microglia. Furthermore, primary cultured microglia were exposed to extracted myelin debris and TGF-β1 in vitro to explore the underlying mechanisms.

RESULTS

As evaluated by behavioral tests, TGF-β1 significantly alleviated the cognitive dysfunction and gait disorder in bilateral common carotid artery stenosis-modeling mice. The demyelinating lesion and remyelination process were also found to be highly improved by activation of the TGF-β1 pathway. The results of immunostaining and electron microscopy showed that TGF-β1 could ameliorate microglial activation and the dysfunction of lipid metabolism in myelin-engulfed microglia. Mechanistically, in primary cultured microglia exposed to myelin debris, administration of TGF-β1 notably mitigated the inflammatory response and accumulation of intracellular lipid droplets via promoting the lipid droplets degradation in the autophagy-lysosomal pathway, as quantified by flow cytometry, immunostaining, Western blot, etc. Yet, the application of autophagy inhibitor (3-methyladenine) significantly reversed the above anti-inflammatory effects of TGF-β1.

CONCLUSIONS

TGF-β1 relieved cognitive deficit, demyelinating lesions, and microglia-mediated neuroinflammation in bilateral common carotid artery stenosis modeling by reducing abnormal lipid droplet accumulation and dysfunction of the autophagy-lysosomal pathway in microglia. Clinically, staged activation of the TGF-β1 pathway may become a potential target and promising treatment for ischemic white matter lesions and vascular cognitive impairment.

Transcriptome analysis provides new insights into the resistance of pepper to Phytophthora capsici infection

BACKGROUND

Phytophthora blight is a highly destructive soil-borne disease caused by Phytophthora capsici Leonian, which threatens pepper production. The molecular mechanism of pepper resistance to phytophthora blight is unclear, and the excavation and functional analysis of resistant genes are the bases and prerequisites for phytophthora blight-resistant breeding. We aimed to analyze the expression patterns of key genes in the plant-pathogen interaction metabolic pathway and propose a working model of the pepper defense signal network against Phytophthora capsici infection.

RESULTS

The 'ZCM334' pepper material used in this study is a high-generation inbred line that is immune to Phytophthora capsici and shows no signs of infection after inoculation. Comparative transcriptome analysis of the roots of 'ZCM334' and the susceptible material 'Early Calwonder' revealed significant differences in their gene expression profiles at different stages after inoculation. Most differentially expressed genes were significantly enriched in the biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, plant-pathogen interaction, and fatty acid degradation metabolic pathways. Some defense genes and transcription factors significant in pepper resistance to phytophthora blight were identified, including PR1, RPP13, FLS2, CDPK, CML, MAPK, RLP, RLK, WRYK, ERF, MYB, and bHLH, most of which were regulated after inoculation. A working model was constructed for the defense signal network of pepper against Phytophthora capsici.

CONCLUSIONS

These data provide a valuable source of information for improving our understanding of the potential molecular mechanisms by which pepper plants resist infection by Phytophthora capsici. The identification of key genes and metabolic pathways provides avenues for further exploring the immune mechanism of 'ZCM334' resistance to phytophthora blight.

CD4+ T-cell metabolism in the pathogenesis of Sjogren's syndrome

The abnormal effector function of CD4+ T cells plays a key role in the pathogenesis of Sjogren's syndrome (SS) and its associated systematic autoimmune response. Cellular metabolism, including glucose metabolism, lipid metabolism and amino acid metabolism, supports proliferation, migration, survival and differentiation into distinct CD4+ T-cell subsets. Different subtypes of T cells have significantly different demands for related metabolic processes, which enables us to finely regulate CD4+ T cells through different metabolic processes in autoimmune diseases such as SS. In this review, we summarize the effects of disturbances in distinct metabolic processes, such as glycolysis, fatty acid metabolism, glutamine decomposition, mitochondrial dynamics, and ferroptosis, on how to support the effector functions of CD4+ T cells in the SS. We also discuss potential drugs with high value in the treatment of SS through metabolic normalization in CD4+ T cells. Finally, we propose possible directions for future targeted therapy for immunometabolism in SS.

Highly Specific Miniaturized Fluorescent Monoacylglycerol Lipase Probes Enable Translational Research

Monoacylglycerol lipase (MAGL) is the pivotal catabolic enzyme responsible for signal termination in the endocannabinoid system. Inhibition of MAGL offers unique advantages over the direct activation of cannabinoid receptors in treating cancer, metabolic disorders, and inflammatory diseases. Although specific fluorescent molecular imaging probes are commonly used for the real-time analysis of the localization and distribution of drug targets in cells, they are almost invariably composed of a linker connecting the pharmacophore with a large fluorophore. In this study, we have developed miniaturized fluorescent probes targeting MAGL by incorporating a highly fluorescent boron-dipyrromethene (BODIPY) moiety into the inhibitor structure that interacts with the MAGL active site. These miniaturized fluorescent probes exhibit favorable drug-like properties such as high solubility and permeability, picomolar potency for MAGL across various species, and high cell selectivity and specificity. A range of translational investigations were conducted, including cell-free fluorescence polarization assays, fluorescence-activated cell sorting analysis, and confocal fluorescence microscopy of live cancer cells, live primary neurons, and human-induced pluripotent stem cell-derived brain organoids. Furthermore, the application of red-shifted analogs or 18F positron emission labeling illustrated the significant versatility and adaptability of the fluorescent ligands in various experimental contexts.

Global Levels and Variations of Cholesterol and Polar Lipids of Human Milk: A Systematic Review and Meta-analysis

Polar lipids and cholesterol are vital structural components of the milk fat globule membrane, playing a crucial role in infant growth and development; however, systematic global reports on their content in human milk are currently lacking. This study conducted a systematic literature search in Chinese and English databases, including 69,392 human milk samples from 96 studies. A random-effects model based on global data was used to assess the content of total lipids, cholesterol, gangliosides, and phospholipids in human milk and their variations with the lactation stage, geographical region, and sample year. The mean contents of total lipids, cholesterol, and total phospholipids were 2774.15 mg/100 g (95% CI: 2614.88, 2933.42 mg/100 g), 21.15 mg/100 g (18.35, 23.95 mg/100 g), and 70.72 mg/100 g (68.84, 72.60 mg/100 g), respectively, with gangliosides GM3 and GD3 at 0.63 mg/100 g (0.54, 0.72 mg/100 g) and 0.34 mg/100 g (0.32, 0.36 mg/100 g). The major phospholipids SM, PC, PE, PS, and PI averaged 24.19 mg/100 g (23.17 and 25.21 mg/100 g), 21.27 mg/100 g (19.92 and 22.62 mg/100 g), 18.28 mg/100 g (17.46 and 19.10 mg/100 g), 2.86 mg/100 g (2.32 and 3.40 mg/100 g), and 2.12 mg/100 g (1.75 and 2.49 mg/100 g). With the progression of lactation, total lipids, gangliosides, and most phospholipids (SM, PC, PS, PI) increased, while cholesterol and PE decreased. Over the years, total lipids, gangliosides, and PE showed an upward trend, whereas cholesterol and most phospholipids declined. Human milk from Europe had lower total lipid and cholesterol levels compared with other regions. While the total phospholipid content did not show significant regional differences (P > 0.05), variations in phospholipid composition were observed. These findings emphasize the importance of understanding spatiotemporal changes in human milk lipids to develop personalized nutrition strategies that support optimal infant growth and development.

Supplementation of mixed Lactobacillus alleviates metabolic impairment, inflammation, and dysbiosis of the gut microbiota in an obese mouse model

Introduction

Obesity is a complex metabolic disease, which is often accompanied with impaired glucose and lipid metabolism and chronic inflammation. Probiotics have been considered as a strategy for treating obesity, while the genus of Lactobacillus is the most commonly tested and approved probiotics. Some multi-strain probiotics were proven to produce synergistic effects on treating obesity as compared to mono-strain ones.

Methods

The purpose of this study was to investigate the anti-obesity effect of a new probiotic formation contained Lactobacillus plantarum L14, Lactobacillus paracasei L9, Lactobacillus rhamnosus GG, and Lactobacillus sakei X-MRS-2, designated as L-PPRS. Multi-strain probiotics L-PPRS was shown to have a better antiadipogenic effect than mono-strain probiotics in 3T3-L1 cell. Subsequently, L-PPRS was orally supplemented to a high-fat diet (HFD) induced obese mouse model for two kinds of treatment course, a short-term (8 weeks) one and a long-term (12 weeks) one.

Results

We found that intervention of L-PPRS not only significantly inhibited weight gain in HFD-fed mice, but also improved glucose tolerance, insulin sensitivity and reduced serum lipid levels. Furthermore, L-PPRS intervention reduced fat accumulation in the adipose tissue and the liver, and ameliorated the antioxidant capacity of liver in HFD-fed mice. L-PPRS intervention modulated the expression of lipid-metabolic genes, and exhibited excellent anti-inflammatory effect. In addition, L-PPRS intervention restored the dysbiosis of gut microbiota via reducing the Firmicutes/ Bacteroidetes ratio, and increasing the abundance of beneficial intestinal bacteria. In conclusion, this study proved that L-PPRS could effectively prevent the development of obesity and its associated abnormalities, and the long-term supplementation of L-PPRS provided a more profound benefit than the short-term.

Discussion

This study highlights the potential of L-PPRS as an effective anti-obesity strategy.

Drying methods affect nutritional value, amino acids, bioactive compounds, and in vitro function of extract in mulberry leaves

Mulberry leaves (ML) are nutrient-rich and beneficial for food and feed. Our study evaluated five drying methods-sun drying (SD), air drying (AD), oven drying (OD), freeze drying (FD), and vacuum-microwave drying (MD) for preserving nutrients and bioactivity. In vitro models tested the bioactivities of ML extracts. Results showed that machine-based methods (OD, FD, and MD) were superior to natural processes (SD, AD) retaining nutrients and bioactivity. OD preserved amino acids effectively, FD and MD retained crude protein and fibers, and MD excelled in maintaining the total polyphenols, vitamin E, minerals, and bioactive compounds, enhancing the antioxidant capacity and beneficial effects on lipid metabolism, ROS scavenging, and anti-apoptotic in lipid-laden HepG2 cells. Overall, FD and MD are ideal for high-value products like food and pharmaceuticals, while OD is cost-effective for animal feed. SD and AD lead to significant nutrient loss and are not recommended unless cost is a major concern.

Critical Review on Anti-Obesity Effects of Anthocyanins Through PI3K/Akt Signaling Pathways

Obesity is a global health crisis and is one of the major reasons for the rising prevalence of metabolic disorders such as type 2 diabetes, cardiovascular diseases, and certain cancers. There has been growing interest in the search for natural molecules with potential anti-obesity effects; among the phytochemicals of interest are anthocyanins, which are flavonoid pigments present in many fruits and vegetables. Anthocyanins influence obesity via several signaling pathways. The PI3K/Akt signaling pathway plays a major role with a focus on downstream targets such as GLUT4, FOXO, GSK3β, and mTOR, which play a central role in the regulation of glucose metabolism, lipid storage, and adipogenesis. The influence of critical factors such as oxidative stress and inflammation also affect the pathophysiology of obesity. However, the studies reviewed have certain limitations, including variations in experimental models, bioavailability challenges, and a lack of extensive clinical validation. While anthocyanin shows tremendous potential, challenges such as poor bioavailability, stability, and regulatory matters must be overcome for successful functional food inclusion of anthocyanins. The future of anthocyanin-derived functional foods lies in their ability to overcome hurdles. Therefore, this review highlights the molecular mechanisms of obesity through the PI3K/Akt signaling pathways and explores how anthocyanins can modulate these signaling pathways to address obesity and related metabolic disorders. It also addresses some ways to solve the challenges, like bioavailability and stability, while emphasizing future possibilities for anthocyanin-based functional foods in obesity management.

Bacterial membrane vesicles restore gut anaerobiosis

Inflammation damages the epithelial cell barrier, allowing oxygen to leak into the lumen of the gut. Respiring E. coli and other Enterobacteriaceae produce proinflammatory lipopolysaccharide, exacerbating inflammatory bowel disease. Here we show that respiring membrane vesicles (MV) from E. coli ameliorate symptoms in a mouse model of gut inflammation. Membrane vesicle treatment diminished weight loss and limited shortening of the colon. Notably, oxygenation of the colonic epithelium was significantly decreased in animals receiving wild type MVs, but not MVs from an E. coli mutant lacking cytochromes. Metatranscriptomic analysis of the microbiome shows an increase in anaerobic Lactobacillaceae and a decrease in Enterobacteriaceae, as well as a general shift towards fermentation in MV-treated mice. This is accompanied by a decrease in proinflammatory TNF-α. We report that MVs may lead to the development of a novel type of a therapeutic for dysbiosis, and for treating IBD.

Tools to Dissect Lipid Droplet Regulation, Players, and Mechanisms

Spurred by the authors' own recent discovery of reactive metabolite-regulated nexuses involving lipid droplets (LDs), this perspective discusses the latest knowledge and multifaceted approaches toward deconstructing the function of these dynamic organelles, LD-associated localized signaling networks, and protein players. Despite accumulating knowledge surrounding protein families and pathways of conserved importance for LD homeostasis surveillance and maintenance across taxa, much remains to be understood at the molecular level. In particular, metabolic stress-triggered contextual changes in LD-proteins' localized functions, crosstalk with other organelles, and feedback signaling loops and how these are specifically rewired in disease states remain to be illuminated with spatiotemporal precision. We hope this perspective promotes an increased interest in these essential organelles and innovations of new tools and strategies to better understand context-specific LD regulation critical for organismal health.

Lipid availability influences ferroptosis sensitivity in cancer cells by regulating polyunsaturated fatty acid trafficking

Ferroptosis is a form of cell death caused by lipid peroxidation that is emerging as a target for cancer therapy, highlighting the need to identify factors that govern ferroptosis susceptibility. Lipid peroxidation occurs primarily on phospholipids containing polyunsaturated fatty acids (PUFAs). Here, we show that even though extracellular lipid limitation reduces cellular PUFA levels, lipid-starved cancer cells are paradoxically more sensitive to ferroptosis. Using mass spectrometry-based lipidomics with stable isotope fatty acid labeling, we show that lipid limitation induces a fatty acid trafficking pathway in which PUFAs are liberated from triglycerides to synthesize highly unsaturated PUFAs such as arachidonic and adrenic acid. These PUFAs then accumulate in phospholipids, including ether phospholipids, to promote ferroptosis sensitivity. Therefore, PUFA levels within cancer cells do not necessarily correlate with ferroptosis susceptibility. Rather, how cancer cells respond to extracellular lipid levels by trafficking PUFAs into proper phospholipid pools contributes to their sensitivity to ferroptosis.

Perturbation of de novo lipogenesis hinders MERS-CoV assembly and release, but not the biogenesis of viral replication organelles

Coronaviruses hijack host cell metabolic pathways and resources to support their replication. They induce extensive host endomembrane remodeling to generate viral replication organelles and exploit host membranes for assembly and budding of their enveloped progeny virions. Because of the overall significance of host membranes, we sought to gain insight into the role of host factors involved in lipid metabolism in cells infected with Middle East respiratory syndrome coronavirus (MERS-CoV). We employed a single-cycle infection approach in combination with pharmacological inhibitors, biochemical assays, lipidomics, and light and electron microscopy. Pharmacological inhibition of acetyl-CoA carboxylase (ACC) and fatty acid synthase (FASN), key host factors in de novo fatty acid biosynthesis, led to pronounced inhibition of MERS-CoV particle release. Inhibition of ACC led to a profound metabolic switch in Huh7 cells, altering their lipidomic profile and inducing lipolysis. However, despite the extensive changes induced by the ACC inhibitor, the biogenesis of viral replication organelles remained unaffected. Instead, ACC inhibition appeared to affect the trafficking and post-translational modifications of the MERS-CoV envelope proteins. Electron microscopy revealed an accumulation of nucleocapsids in early budding stages, indicating that MERS-CoV assembly is adversely impacted by ACC inhibition. Notably, inhibition of palmitoylation resulted in similar effects, while supplementation of exogenous palmitic acid reversed the compound's inhibitory effects, possibly reflecting a crucial need for palmitoylation of the MERS-CoV spike and envelope proteins for their role in virus particle assembly.IMPORTANCEMiddle East respiratory syndrome coronavirus (MERS-CoV) is the etiological agent of a zoonotic respiratory disease of limited transmissibility between humans. However, MERS-CoV is still considered a high-priority pathogen and is closely monitored by WHO due to its high lethality rate of around 35% of laboratory-confirmed infections. Like other positive-strand RNA viruses, MERS-CoV relies on the host cell's endomembranes to support various stages of its replication cycle. However, in spite of this general reliance of MERS-CoV replication on host cell lipid metabolism, mechanistic insights are still very limited. In our study, we show that pharmacological inhibition of acetyl-CoA carboxylase (ACC), a key enzyme in the host cell's fatty acid biosynthesis pathway, significantly disrupts MERS-CoV particle assembly without exerting a negative effect on the biogenesis of viral replication organelles. Furthermore, our study highlights the potential of ACC as a target for the development of host-directed antiviral therapeutics against coronaviruses.

Identification of lysosomal lipolysis as an essential noncanonical mediator of adipocyte fasting and cold-induced lipolysis

Adipose tissue lipolysis is the process by which triglycerides in lipid stores are hydrolyzed into free fatty acids (FFAs), serving as fuel during fasting or cold-induced thermogenesis. Although cytosolic lipases are considered the predominant mechanism of liberating FFAs, lipolysis also occurs in lysosomes via lysosomal acid lipase (LIPA), albeit with unclear roles in lipid storage and whole-body metabolism. We found that adipocyte LIPA expression increased in adipose tissue of mice when lipolysis was stimulated during fasting, cold exposure, or β-adrenergic agonism. This was functionally important, as inhibition of LIPA genetically or pharmacologically resulted in lower plasma FFAs under lipolytic conditions. Furthermore, adipocyte LIPA deficiency impaired thermogenesis and oxygen consumption and rendered mice susceptible to diet-induced obesity. Importantly, lysosomal lipolysis was independent of adipose triglyceride lipase, the rate-limiting enzyme of cytosolic lipolysis. Our data suggest a significant role for LIPA and lysosomal lipolysis in adipocyte lipid metabolism beyond classical cytosolic lipolysis.

Macrophage foam cell-derived mediator promotes spontaneous fat lipolysis in atherosclerosis models

Ectopic lipid accumulation in macrophages is responsible for the formation of macrophage foam cells (MFCs) which are involved in the crosstalk with the perivascular adipose tissue (PVAT) of the vascular wall that plays a pivotal role in the progression of atherosclerosis. However, the interrelationship between MFCs and PVAT implementing adipocyte dysfunction during atherosclerosis has not yet been established. We hypothesized that MFC-secreted mediator(s) is causally linked with PVAT dysfunction and the succession of atherosclerosis. To test this hypothesis, MFCs were cocultured with adipocytes, or the conditional media of MFCs (MFC-CM) were exposed to adipocytes and found a significant induction of fat lipolysis in adipocytes. The molecular filtration followed by the high-performance liquid chromatography (HPLC) fractionation and liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis of MFC-CM revealed a novel mediator fetuin-A (FetA) that significantly augments toll-like receptor 4 (TLR4)-dependent fat lipolysis in adipocytes. Mechanistically, MFC-derived FetA markedly increased TLR4-dependent c-Jun N-terminal kinases (JNK)/extracellular signal-regulated kinases (ERK) activation that causes spontaneous fat lipolysis implementing adipocyte dysfunction. Thus, the present study provides the first evidence of MFC-derived FetA that induces adipocyte dysfunction by the stimulation of spontaneous fat lipolysis. Therefore, targeting the crosstalk between MFCs and adipocytes could be a newer approach to counter the progression of atherosclerosis.

How pathogens drive adipose tissue loss in the host

Weight loss is a hallmark of many infections, including those caused by bacteria, fungi and parasites. This loss is often attributed to infection-induced anorexia and the need to mobilise energy from internal sources to cope with the pathogens. Weight loss during infection results from a significant reduction of muscle and fat mass, two organs that together account for approximately 60% of body mass in the healthy state. While muscle wasting is a well-documented aspect of infection-related weight loss, adipose tissue loss via lipolysis also plays a critical role and can determine disease outcomes. This review explores the regulators of adipose tissue depletion via excessive lipolysis during infection, the probable mechanisms, and the potential consequences for host survival and pathogen fitness.

Reprogramming of Thyroid Cancer Metabolism: from Mechanism to Therapeutic Strategy

Thyroid cancer as one of the most prevalent malignancies of endocrine system, has raised public concern and more research on its mechanism and treatment. And metabolism-based therapies have advanced rapidly, for the exclusive metabolic profiling of thyroid cancer. In thyroid cancer cells, plenty of metabolic pathways are reprogrammed to accommodate tumor microenvironment. In this review, we initiatively summarize recent progress in the full-scale thyroid cancer metabolic rewiring and the interconnection of various metabolites. We also discuss the efficacy and prospect of metabolic targeted detection as well as therapy. Comprehending metabolic mechanism and characteristics of thyroid cancer roundly will be highly beneficial to managing individual patients.

The circular RNA circbabo(5,6,7,8S) regulates lipid metabolism and neuronal integrity via TGF-β/ROS/JNK/SREBP signaling axis in Drosophila

BACKGROUND

Lipid droplets (LDs) are dynamic cytoplasmic lipid-storing organelles that play a pivotal role in maintaining cellular energy balance, lipid homeostasis, and metabolic signaling. Dysregulation of lipid metabolism, particularly excessive lipogenesis, contributes to the abnormal accumulation of LDs in the nervous system, which is associated with several neurodegenerative diseases. Circular RNAs (circRNAs) are a new class of non-coding and regulatory RNAs that are widely expressed in eukaryotes. However, only a subset has been functionally characterized. Here, we identified and functionally characterized a new circular RNA circbabo(5,6,7,8S) that regulates lipogenesis and neuronal integrity in Drosophila melanogaster.

RESULTS

circbabo(5,6,7,8S) is derived from the babo locus which encodes the type I receptor for transforming growth factor β (TGF-β). Depletion of circbabo(5,6,7,8S) in flies causes elevated lipid droplet accumulation, progressive photoreceptor cell loss and shortened lifespan, phenotypes that are rescued by restoring circbabo(5,6,7,8S) expression. In addition, RNA-seq and epistasis analyses reveal that these abnormalities are caused by aberrant activation of the SREBP signaling pathway. Furthermore, circbabo(5,6,7,8S)-depleted tissues display enhanced activation of the TGF-β signaling pathway and compromised mitochondrial function, resulting in upregulation of reactive oxygen species (ROS). Moreover, we provide evidence that circbabo(5,6,7,8S) encodes the protein circbabo(5,6,7,8S)-p, which inhibits TGF-β signaling by interfering with the assembly of babo/put receptor heterodimer complex. Lastly, we show that dysregulation of the ROS/JNK/SREBP signaling cascade is responsible for the LD accumulation, neurodegeneration, and shortened lifespan phenotypes elicited by circbabo(5,6,7,8S) depletion.

CONCLUSIONS

Our study demonstrates the physiological role of the protein-coding circRNA circbabo(5,6,7,8S) in regulating lipid metabolism and neuronal integrity.

The Power of Exercise: Unlocking the Biological Mysteries of Peripheral-Central Crosstalk in Parkinson's Disease

BACKGROUND

Exercise is a widely recognized non-pharmacological treatment for Parkinson's Disease (PD). The bidirectional regulation between the brain and peripheral organs has emerged as a promising area of research, with the mechanisms by which exercise impacts PD closely linked to the interplay between peripheral signals and the central nervous system.

AIM OF REVIEW

This review aims to summarize the mechanisms by which exercise influences peripheral-central crosstalk to improve PD, discuss the molecular processes mediating these interactions, elucidate the pathways through which exercise may modulate PD pathophysiology, and identify directions for future research.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This review examines how exercise-induced cytokine release promotes neuroprotection in PD. It discusses how exercise can stimulate cytokine secretion through various pathways, including the gut-brain, muscle-brain, liver-brain, adipose-brain, and bone-brain axes, thereby alleviating PD symptoms. Additionally, the potential contributions of the heart-brain, lung-brain, and spleen-brain axes, as well as multi-axis crosstalk-such as the brain-gut-muscle and brain-gut-bone axes-are explored in the context of exercise therapy. The study highlights the need for further research into peripheral-central crosstalk and outlines future directions to address challenges in clinical PD therapy.

A Highly Selective and Versatile Probe Platform for Visualization of Monoacylglycerol Lipase

Monoacylglycerol lipase (MAGL) is a key enzyme for signal termination in the endocannabinoid system (ECS). MAGL inhibition results in indirect activation of the cannabinoid receptors, which offers unique advantages for the treatment of, e.g., multiple sclerosis, epilepsy, and other neurological disorders. Molecular imaging techniques are valuable tools to overcome the current poor understanding of MAGL's distribution and role in patho- and physiological processes within ECS signaling. Herein, we report the design, synthesis, and validation of highly selective versatile fluorescent and click-chemistry probes for MAGL. Structure-based design combined with a reverse-design approach allowed the development of a structural unit that selectively and effectively recognizes MAGL while offering a versatile platform to attach different fluorophores and further reporter units. In this way, labeled probes with sub-nanomolar potency carrying diverse fluorescent dyes were obtained. Probe affinity and selectivity remained invariant to changes in the fluorophore subunit, showing the remarkable robustness of this platform in delivering tailor-made probes. Highly consistent inhibition across species supports pharmacological model translatability. Extensive profiling and validation in various cellular systems shows the ability of these highly potent and selective probes to elucidate the complex role of MAGL in ECS cellular signaling, inflammatory processes, and disease progression.

Silencing FAF2 mitigates alcohol-induced hepatic steatosis by modulating lipolysis and PCSK9 pathway

BACKGROUND

Chronic alcohol consumption leads to lipid accumulation, oxidative stress, cellular damage, and inflammation in the liver, collectively referred to as alcohol-associated liver disease (ALD). FAF2/UBXD8/ETEA (Fas-associated factor 2) is a ubiquitin ligase adaptor protein that plays a crucial role in the ubiquitin-mediated degradation of misfolded proteins in the endoplasmic reticulum. A recent genome-wide association study indicated an association between FAF2 and ALD; however, the exact contribution of FAF2 to ALD pathogenesis remains unclear.

METHODS

FAF2 was knocked down using AAV-delivered shRNA in C57/BL6 mice. Mice were subjected to a chronic-plus-single binge ethanol feeding (NIAAA) model. Nine hours after gavage, liver, blood, and other organs of interest were collected for gene expression and biochemical analyses.

RESULTS

We first observed a significant elevation in hepatic FAF2 protein expression in individuals with ALD and in mice subjected to an ethanol-binge model. Interestingly, knocking down FAF2 in the liver using adeno-associated virus serotype 8-delivered short hairpin RNA conferred a protective effect against alcohol-induced liver steatosis in ethanol-binged mice. Transcriptomic analysis revealed that differentially expressed genes were enriched in multiple lipid metabolism regulation pathways. Further analysis of transcription factors regulating these differentially expressed genes suggested potential regulation by SREBP1. Several SREBP1 target genes, including Fasn, Scd1, Lpin1, and Pcsk9 (proprotein convertase subtilisin/kexin type 9), were dysregulated in the livers of ethanol-fed FAF2 knockdown mice. Additionally, Pcsk9 could be regulated through the FOXO3-SIRT6 pathway in the livers of ethanol-fed FAF2 knockdown mice, leading to increased liver low-density lipoprotein receptor expression and reduced plasma LDL cholesterol levels. Furthermore, FAF2 knockdown in mouse liver enhanced adipose triglyceride lipase lipolytic activity by upregulating the adipose triglyceride lipase activator, comparative gene identification-58, and downregulating the adipose triglyceridelipase transport inhibitor, Elmod2, contributing to the alleviation of liver steatosis.

CONCLUSIONS

Our study uncovers a novel mechanism involving FAF2 in the pathogenesis of ALD.

mTORC1 and 2 Adrenergic Regulation and Function in Brown Adipose Tissue

Brown adipose tissue (BAT) thermogenesis results from the uncoupling of mitochondrial inner membrane proton gradient mediated by uncoupling protein 1 (UCP-1), which is activated by lipolysis-derived fatty acids. Norepinephrine (NE) secreted by sympathetic innervation not only activates BAT lipolysis and UCP-1 but, uniquely in brown adipocytes, promotes "futile" metabolic cycles and enhances BAT thermogenic capacity by increasing UCP-1 content, mitochondrial biogenesis, and brown adipocyte hyperplasia. NE exerts these actions by triggering signaling in the canonical G protein-coupled β-adrenergic receptors, cAMP, and protein kinase A (PKA) pathway, which in brown adipocytes is under a complex and intricate cross talk with important growth-promoting signaling pathways such as those of mechanistic target of rapamycin (mTOR) complexes 1 (mTORC1) and 2 (mTORC2). This article reviews evidence suggesting that mTOR complexes are modulated by and participate in the thermogenic, metabolic, and growth-promoting effects elicited by NE in BAT and discusses current gaps and future directions in this field of research.

Impaired mitochondrial integrity and compromised energy production underscore the mechanism underlying CoASY protein-associated neurodegeneration

Coenzyme A (CoA) is a crucial metabolite involved in various biological processes, encompassing lipid metabolism, regulation of mitochondrial function, and membrane modeling. CoA deficiency is associated with severe human diseases, such as Pantothenate Kinase-Associated Neurodegeneration (PKAN) and CoASY protein-associated neurodegeneration (CoPAN), which are linked to genetic mutations in Pantothenate Kinase 2 (PANK2) and CoA Synthase (CoASY). Although the association between CoA deficiency and mitochondrial dysfunction has been established, the underlying molecular alterations and mechanisms remain largely elusive. In this study, we investigated the detailed changes resulting from the functional decline of CoASY using the Drosophila model. Our findings revealed that a reduction of CoASY in muscle and brain led to degenerative phenotypes and apoptosis, accompanied by impaired mitochondrial integrity. The release of mitochondrial DNA was notably augmented, while the assembly and activity of mitochondrial electron transport chain (ETC) complexes, particularly complex I and III, were diminished. Consequently, this resulted in decreased ATP generation, rendering the fly more susceptible to energy insufficiency. Our findings suggest that compromised mitochondrial integrity and energy supply play a crucial role in the pathogenesis associated with CoA deficiency, thereby implying that enhancing mitochondrial integrity can be considered a potential therapeutic strategy in future interventions.

Deciphering the anti-obesity mechanisms of pharmabiotic probiotics through advanced multiomics analysis

Probiotics with "pharmabiotic" properties are increasingly recognized as effective tools for combating obesity by altering gut microbiota and reducing body fat. However, the molecular mechanisms underlying their anti-obesity effects remain largely unexplored due to the absence of a universal methodology. Herein, we developed a multiomics-based strategy to elucidate how probiotics reduce lipid production in adipocytes. Our initial investigation assessed the impact of probiotics at defined adipocyte differentiation stages. Leveraging these insights, we performed comprehensive multiomics analyses at key intervals to identify the suppression mechanisms of lipid formation. Lactobacillus reuteri, specifically, targets early differentiation stages, inhibits branched-chain amino acid catabolism, and reduces lipid accumulation in adipocytes by suppressing Krüppel-like factor 5. Concurrently, enhanced hypoxia-inducible factor 1 expression impedes adipogenesis by downregulating lipin-1 expression. This study not only demonstrates the effectiveness of our approach in revealing complex host-microbe interactions but also significantly advances probiotic therapeutic development, offering promising avenues for obesity management.

Molecular Mechanisms Underlying Heart Failure and Their Therapeutic Potential

Heart failure (HF) is a prominent fatal cardiovascular disorder afflicting 3.4% of the adult population despite the advancement of treatment options. Therefore, a better understanding of the pathogenesis of HF is essential for exploring novel therapeutic strategies. Hypertrophy and fibrosis are significant characteristics of pathological cardiac remodeling, contributing to HF. The mechanisms involved in the development of cardiac remodeling and consequent HF are multifactorial, and in this review, the key underlying mechanisms are discussed. These have been divided into the following categories thusly: (i) mitochondrial dysfunction, including defective dynamics, energy production, and oxidative stress; (ii) cardiac lipotoxicity; (iii) maladaptive endoplasmic reticulum (ER) stress; (iv) impaired autophagy; (v) cardiac inflammatory responses; (vi) programmed cell death, including apoptosis, pyroptosis, and ferroptosis; (vii) endothelial dysfunction; and (viii) defective cardiac contractility. Preclinical data suggest that there is merit in targeting the identified pathways; however, their clinical implications and outcomes regarding treating HF need further investigation in the future. Herein, we introduce the molecular mechanisms pivotal in the onset and progression of HF, as well as compounds targeting the related mechanisms and their therapeutic potential in preventing or rescuing HF. This, therefore, offers an avenue for the design and discovery of novel therapies for the treatment of HF.

Analysis and Comparison of Lipids in Monascus-Fermented Cheese from Different Ripening Periods Based on UHPLC-QTRAP MS Quantitative Lipidomics

Monascus-fermented cheese (MC) is a new cheese product that undergoes a multistrain fermentation process, which results in unique flavor qualities. Lipid metabolism plays an important role in the flavor formation of MC. To clarify the lipid composition of MC and the changes in lipid composition at four ripening periods, this study resolved the lipid profiles of MC by using UHPLC-QTRAP MS. The results identified 21 lipid classes and 748 lipid species, 72 of which were significantly different (VIP > 1, p < 0.01, |log 2FC| > 1). Additionally, 83 relevant metabolic pathways were enriched. Based on the enriched metabolic pathways and lipid changes, the pathways of differential lipid formation in MC were mapped. The results of this study comprehensively characterize the changes in lipids during the ripening process of MC, which can be used in the future to deeply analyze the mechanism of flavor formation in MC.

Histopathological and Proteomics Analysis of Shrimp Litopenaeus vannamei Infected with Ecytonucleospora hepatopenaei

Ecytonucleospora hepatopenaei (EHP) is a microsporidian pathogen that primarily infects the hepatopancreas of Litopenaeus vannamei. Previous studies on EHP detection primarily focused on histology, in situ hybridization (ISH), and PCR, mainly concentrating on hepatopancreatic infections, with limited research on extra-hepatopancreatic tissues. This study investigates the pathogenic mechanisms of EHP infection in L. vannamei through molecular quantification, histopathology, and proteomics analysis. RT-qPCR was employed to examine the infection differences across various tissues at the molecular level, revealing that the hepatopancreas, stomach, midgut, muscle, gills, and antennal glands are susceptible tissues. Pathological analysis, combining H&E staining, Masson's trichrome staining, and immunohistochemistry, identified the EHP-targeted sites at the tissue level. Masson's staining effectively highlighted fibrosis, unveiling the histopathological characteristics of chronic EHP infection, while immunohistochemistry enhanced the specificity of EHP localization. The pathological features of EHP infection were primarily characterized by inflammation, cell degeneration and necrosis, and the accumulation of microsporidia in the cytoplasm. Proteomics analysis was used to interpret the histopathological findings, revealing significant enrichment of pathways related to inflammation, immune regulation, metabolism, and apoptosis regulation. These findings provide new insights into the infection mechanisms and tissue tropism of EHP.

Near-Native Imaging of Metal Ion-Initiated Cell State Transition

Metal ions are indispensable to life, as they can serve as essential enzyme cofactors to drive fundamental biochemical reactions, yet paradoxically, excess is highly toxic. Higher-order cells have evolved functionally distinct organelles that separate and coordinate sophisticated biochemical processes to maintain cellular homeostasis upon metal ion stimuli. Here, we uncover the remodeling of subcellular architecture and organellar interactome in yeast initiated by several metal ion stimulations, relying on near-native three-dimensional imaging, cryo-soft X-ray tomography. The three-dimensional architecture of intact yeast directly shows that iron or manganese triggers a hormesis-like effect that promotes cell proliferation. This process leads to the reorganization of organelles in the preparation for division, characterized by the polar distribution of mitochondria, an increased number of lipid droplets (LDs), volume shrinkage, and the formation of a hollow structure. Additionally, vesicle-like structures that detach from the vacuole are observed. Oppositely, cadmium or mercury causes stress-associated phenotypes, including mitochondrial fragmentation, LD swelling, and autophagosome formation. Notably, the organellar interactome, encompassing the interactions between mitochondria and LDs and those between the nuclear envelope and LDs, is quantified and exhibits alteration with multifaceted features in response to different metal ions. More importantly, the dynamics of organellar architecture render them more sensitive biomarkers than traditional approaches for assessing the cell state. Strikingly, yeast has a powerful depuration capacity to isolate and transform the overaccumulated cadmium in the vacuole, mitochondria, and cytoplasm as a high-value product, quantum dots. This work presents the possibility of discovering fundamental links between organellar morphological characteristics and the cell state.

Oxidative Stress and Reprogramming of Lipid Metabolism in Cancers

Oxidative stress is a common event involved in cancer pathophysiology, frequently accompanied by unique lipid metabolic reprogramming phenomena. Oxidative stress is caused mainly by an imbalance between the production of reactive oxygen species (ROS) and the antioxidant system in cancer cells. Emerging evidence has reported that oxidative stress regulates the expression and activity of lipid metabolism-related enzymes, leading to the alteration of cellular lipid metabolism; this involves a significant increase in fatty acid synthesis and a shift in the way in which lipids are taken up and utilized. The dysregulation of lipid metabolism provides abundant intermediates to synthesize biological macromolecules for the rapid proliferation of cancer cells; moreover, it contributes to the maintenance of intracellular redox homeostasis by producing a variety of reducing agents. Moreover, lipid derivatives and metabolites play critical roles in signal transduction within cancer cells and in the tumor microenvironment that evades immune destruction and facilitates tumor invasion and metastasis. These findings suggest a close relationship between oxidative stress and lipid metabolism during the malignant progression of cancers. This review focuses on the crosstalk between the redox system and lipid metabolic reprogramming, which provides an in-depth insight into the modulation of ROS on lipid metabolic reprogramming in cancers and discusses potential strategies for targeting lipid metabolism for cancer therapy.