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Conventionally, the size, shape, and biomechanics of cartilages are determined by their voluminous extracellular matrix. By contrast, we found that multiple murine cartilages consist of lipid-filled cells called lipochondrocytes. Despite resembling adipocytes, lipochondrocytes were molecularly distinct and produced lipids exclusively through de novo lipogenesis. Consequently, lipochondrocytes grew uniform lipid droplets that resisted systemic lipid surges and did not enlarge upon obesity. Lipochondrocytes also lacked lipid mobilization factors, which enabled exceptional vacuole stability and protected cartilage from shrinking upon starvation. Lipid droplets modulated lipocartilage biomechanics by decreasing the tissue's stiffness, strength, and resilience. Lipochondrocytes were found in multiple mammals, including humans, but not in nonmammalian tetrapods. Thus, analogous to bubble wrap, superstable lipid vacuoles confer skeletal tissue with cartilage-like properties without "packing foam-like" extracellular matrix.

Excessive fructose intake is a risk factor for the development of obesity and its complications. Targeting ketohexokinase (KHK), the first enzyme of fructose metabolism, has been investigated for the management of metabolic dysfunction-associated steatotic liver disease (MASLD). We compared the effects of systemic, small molecule inhibitor of KHK enzymatic activity with hepatocyte-specific, N-acetylgalactosamine siRNA-mediated knockdown of KHK in mice on an HFD. We measured KHK enzymatic activity, extensively quantified glycogen accumulation, performed RNA-Seq analysis, and enumerated hepatic metabolites using mass spectrometry. Both KHK siRNA and KHK inhibitor led to an improvement in liver steatosis; however, via substantially different mechanisms, KHK knockdown decreased the de novo lipogenesis pathway, whereas the inhibitor increased the fatty acid oxidation pathway. Moreover, KHK knockdown completely prevented hepatic fructolysis and improved glucose tolerance. Conversely, the KHK inhibitor only partially reduced fructolysis, but it also targeted triokinase, mediating the third step of fructolysis. This led to the accumulation of fructose-1 phosphate, resulting in glycogen accumulation, hepatomegaly, and impaired glucose tolerance. Overexpression of wild-type, but not kinase-dead, KHK in cultured hepatocytes increased hepatocyte injury and glycogen accumulation after treatment with fructose. The differences between KHK inhibition and knockdown are, in part, explained by the kinase-dependent and -independent effects of KHK on hepatic metabolism.

Liver X receptor-α (LXRα) regulates cellular cholesterol abundance and potently activates hepatic lipogenesis. Here we show that at least 1 in 450 people in the UK Biobank carry functionally impaired mutations in LXRα, which is associated with biochemical evidence of hepatic dysfunction. On a western diet, male and female mice homozygous for a dominant negative mutation in LXRα have elevated liver cholesterol, diffuse cholesterol crystal accumulation and develop severe hepatitis and fibrosis, despite reduced liver triglyceride and no steatosis. This phenotype does not occur on low-cholesterol diets and can be prevented by hepatocyte-specific overexpression of LXRα. LXRα knockout mice exhibit a milder phenotype with regional variation in cholesterol crystal deposition and inflammation inversely correlating with steatosis. In summary, LXRα is necessary for the maintenance of hepatocyte health, likely due to regulation of cellular cholesterol content. The inverse association between steatosis and both inflammation and cholesterol crystallization may represent a protective action of hepatic lipogenesis in the context of excess hepatic cholesterol.

Disordered eating behavior differs between the restricting subtype (AN-R) and the binging and purging subtype (AN-BP) of anorexia nervosa (AN). Yet, little is known about how these differences impact fatty acid (FA) dysregulation in AN. To address this question, we analyzed 26 FAs and 7 FA lipogenic enzymes (4 desaturases and 3 elongases) in 96 women: 25 AN-R, 25 AN-BP, and 46 healthy control women. Our goal was to assess subtype-specific patterns. Lauric acid was significantly higher in AN-BP than in AN-R at the fasting timepoint (p = 0.038) and displayed significantly different postprandial changes 2 h after eating. AN-R displayed significantly higher levels of n-3 alpha-linolenic acid, stearidonic acid, eicosapentaenoic acid (EPA), docosapentaenoic acid, and n-6 linoleic acid and gamma-linolenic acid compared to controls. AN-BP showed elevated EPA and saturated lauric acid compared to controls. Higher EPA was associated with elevated anxiety in AN-R (p = 0.035) but was linked to lower anxiety in AN-BP (p = 0.043). These findings suggest distinct disordered eating behaviors in AN subtypes contribute to lipid dysregulation and eating disorder comorbidities. A personalized dietary intervention may improve lipid dysregulation and enhance treatment effectiveness for AN.

The liver plays a central role in regulating lipid and glucose metabolism, particularly in transitioning between energy storage and provision in fed and fasting states. Loss of metabolic flexibility, characterized by the impaired capacity to shift between different energy substrates, sets the stage for accumulation of hepatic triglyceride as lipid droplets and further metabolic perturbations. Cross talk between the liver and other organs, including adipose tissue, pancreas, and muscle, is relevant in this transition. In addition to the metabolic consequences of steatosis, there are significant liver risks related to triggered inflammatory and fibrotic processes. Steatotic liver diseases affect an estimated one in three adults globally and contribute to substantial morbidity and mortality. This review focuses on the liver's role in lipid metabolism, defining metabolic health and unhealth, the pathogenic underpinnings that lead to steatohepatitis and hepatic fibrosis, and the clinical features and therapies for the most common forms of steatotic liver diseases. [ABSTRACT FROM AUTHOR]

Background and objectives: Statins are used for metabolic dysfunction‐associated steatotic liver disease (MASLD) (NAFLD) treatment, but their role in this context is unclear. Genetic variants of patatin‐like phospholipase domain containing 3 (PNPLA3) are associated with MASLD susceptibility and statin treatment efficacy. Access to liver biopsies before established MASLD is limited, and statins and PNPLA3 in early liver steatosis are thus difficult to study. Methods: Liver biopsies were collected from 261 patients without known liver disease at surgery and stratified based on statin use and criteria for the metabolic syndrome (MS). Genotypes and transcript levels were measured using Illumina and Affymetrix arrays, and metabolic and lipoprotein profiles by clinical assays. Statin effects on PNPLA3, de novo lipogenesis (DNL), and lipid accumulation were further studied in vitro. Results: The PNPLA3I148M genetic variant was associated with significantly lower hepatic levels of cholesterol synthesis‐associated transcripts. Patients with MS had significantly higher hepatic levels of MASLD and lipogenesis‐associated transcripts than non‐MS patients. Patients with MS on statin therapy had significantly higher hepatic levels of PNPLA3, acetyl‐CoA carboxylase alpha, and ATP citrate lyase, and statin use was associated with higher plasma fasting glucose, insulin, and HbA1c. Exposure of hepatocyte‐like HepG2 cells to atorvastatin promoted intracellular accumulation of triglycerides and lipogenesis‐associated transcripts. Atorvastatin‐exposure of HepG2, sterol O‐acyltransferase (SOAT) 2‐only‐HepG2, primary human hepatic stellate, and hepatic stellate cell‐like LX2 cells significantly increased levels of PNPLA3 and SREBF2‐target genes, whereas knockdown of SREBF2 attenuated this effect. Conclusions: Collectively, these observations suggest statin‐associated regulation of PNPLA3 and DNL in liver. The potential interaction between PNPLA3 genotype and metabolic status should be considered in future studies in the context of statin therapy for MASLD. [ABSTRACT FROM AUTHOR]

Malabar snapper (Lutjanus malabaricus) is an economically important marine fish throughout the Indo‐Pacific, with an emerging aquaculture industry. Although generic marine feeds are available for production, these are not optimised for this species. Understanding energy utilisation and balance can provide insight into suitable macronutrient profiles for new species to provide a baseline for future development. This study, therefore, evaluated the effect of dietary macronutrient composition (i.e., protein, fat, and carbohydrate) on the utilisation efficiencies of digestible energy (DE) in juvenile Malabar snapper using two isonitrogenous diets (high fat: HF and low fat: LF) with contrasting fat and carbohydrate content. Each diet was fed at four feeding levels (100%, 75%, 50%, and 25% apparent satiation) for 56 days, creating a 2 by 4 factorial design. The maintenance energy requirement of Malabar snapper was estimated to be 76.7 kJ kg−0.8 day−1, while the utilisation efficiencies of digestible protein (DP) and fat were 73.6% and 68.3%, respectively. Fish fed with LF, which has lower dietary fat and higher dietary carbohydrate levels, had significantly reduced energy utilisation efficiency for growth and significantly higher partial energy utilisation efficiency of digestible fat (DF) (p < 0.05). Since body moisture is usually proportional to body fat content in fish, this implies that the energy from carbohydrates preferentially enters lipogenesis rather than being available for somatic growth, and adiposity does not directly result in weight gain. Malabar snapper utilises DF in preference to protein for metabolism, demonstrating a protein‐sparing effect from lipids at DE intake levels below the maintenance requirement. Conversely, given the higher efficiency of fat retention than protein retention, protein is likely used before fat when energy intake is above maintenance. These findings suggest that Malabar snapper requires high levels of DP in its diet to support growth and that energy from dietary carbohydrates is diverted towards adiposity, consequently reducing growth. [ABSTRACT FROM AUTHOR]

Sucralose, a commonly nonnutritive sweetener used in daily products of habitual diet, is related to impairing the gut microbiome by disrupting inflammatory response, promoting weight gain by increasing adipose tissue and promoting chronic inflammatory processes. Considering the impact of sucralose in the development of metabolic diseases, in this work, we focused on the impact of sucralose on the adipocyte differentiation process to determine if sucralose can promote adipogenesis and increase adipose tissue depots in PCS 210 010 human preadipocytes cell line. Sucralose at 25 (S25) and 100 ng/µL (S100) concentrations were tested against control with no edulcorant (NS) during the adipocyte differentiation process at 48 h and 96 h. The genetic expression of adipogenesis markers such as CEBP-α, PPARγ, EBF-2, UCP-1, and lipogenesis regulator ACC was determined by qPCR. A panel of human cytokines related to inflammatory response was measured by a flow cytometer using the kit Legend Plex Human Cytokine panel of BIOLUMINEX. Our results indicate that sucralose increased the expression of white adipocyte differentiation marker CEBP-α and lipogenesis regulator ACC at 96 h before complete differentiation. Also, sucralose triggers an inflammatory response by synthesizing adiponectin, resistin, IL-6, IL-8, and Il-1B. To summarize, sucralose stimulates the expression of genes related to adipogenesis and negatively affects the secretion of inflammatory cytokines and adipokines during preadipocyte differentiation. [ABSTRACT FROM AUTHOR]

Background and Aim Methods Results Conclusion Krüppel‐like factors15 (KLF15) is a cancer suppressor in many cancers. However, its precise function in the development of hepatocellular carcinoma (HCC) remains unclear. Lipogenesis is necessary for the development of HCC. This research aims to investigate the role of KLF15 in the regulation of hepatic lipid production and HCC progression.The binding relationships among genes were confirmed by ChIP, dual luciferase assays, and Co‐IP. Lipogenesis was examined by oil red O staining. Triglyceride and cholesterol levels were measured through commercial kits. The effect of treatment on HCC cell viability, proliferation, migration, and invasion were assessed using CCK‐8, clone formation, or transwell assays. A subcutaneous tumorigenic model was utilized to explore the effects of PDLIM2 in HCC in vivo.KLF15 were downregulated in human HCC tissues. KLF15 overexpression reduced lipid droplet production, suppressed the expression of genes associated with lipogenesis, and promoted cell proliferation, migration, and invasion. KLF15 suppressed the NF‐κB pathway through transcriptional activation of PDLIM2. PDLIM2 knockdown attenuated the effect of KLF15 overexpression on HCC. WSB2 degraded KLF15 through ubiquitination to promote HCC lipogenesis and development.The ubiquitination degradation of KLF15 was mediated by WSB2, which led to transcriptional repression of PDLIM2 and further activation of the NF‐κB pathway, ultimately promoting HCC lipogenesis and development. [ABSTRACT FROM AUTHOR]

Background: Monotherapy to treat obesity‐associated liver insult is limited. Objectives: In diet‐induced obese mice showing metabolic dysfunction‐associated steatotic liver disease (MASLD), we aimed to compare the combinations of sodium‐glucose cotransporter‐2 inhibitor (SGLT2i, empagliflozin, E), dipeptidyl peptidase‐4 inhibitor (DPP4i, linagliptin, L), and glucagon‐like peptide type 1 receptor agonist (GLP1RA, dulaglutide, D). Methods: Male 3‐month‐old C57BL/6J mice were fed for 12 weeks in a control (C, n = 10) or high‐fat (HF, n = 30) diet. Then, mice were followed for three additional weeks: C, HF, HF E + L, and HF E + D (n = 10/group). Results: HF versus C showed higher hepatic triacylglycerol (TAG, +82%), steatosis (+850%), glucose intolerance (+71%), insulin (+98%), and insulin resistance (+68%). Compared to the HF group, HF E + L showed lower glucose intolerance (−60%), insulin (−61%), insulin resistance (−46%), TAG (−61%), and steatosis (−58%), and HF E + D showed lower glucose intolerance (−71%), insulin (−58%), insulin resistance (−62%), TAG (−61%), and steatosis (−82%). The principal component analysis (PCA) placed the HF group and the HF E + D group on opposite sides, while the HF E + L group was placed between C and HF E + D. Conclusion: PCA separated the groups considering the metabolism‐related genes (glucose and lipid), mitochondrial biogenesis, and steatosis. The two pharmacological combinations showed beneficial effects in treating obesity and MASLD. However, the combination of SGLT2i and GLP1RA showed more potent beneficial effects on MASLD than SGLT2i and DPP4i and, therefore, should be the recommended combination. [ABSTRACT FROM AUTHOR]

Reductive stress, characterized by rising level of NADH (nicotinamide adenine dinucleotide) for a status of NADH/NAD+ ratio elevation, has been reported in obesity and cancer. However, the mechanism and significance of reductive stress remain to be established in obesity. This perspective is prepared to address the issue with new insights published recently. NADH is used in production of NADPH, glutathione, ATP and heat in the classical biochemistry. In obesity, elevation of NADH/NAD+ ratio, likely from overproduction due to substrate overloading, has been found in the liver for insulin resistance and gluconeogenesis. New evidence demonstrates that the elevation may induce lipogenesis, purine biosynthesis and gluconeogenesis through activation of transcription factors of ChREBP and NRF2. In cancer cells, NADH/NAD+ elevation under the Warburg effect is primarily derived from decreased NADH consumption in the mitochondrial respiration. Alternatively, NRF2 overactivation from gene mutation represents another mechanism of NADH/NAD+ elevation from NADH production in the cancer cells. The elevation is required for quick proliferation of cancer cells through induction of biosynthesis of the essential molecules. It appears that the causes of reductive stress are different between obesity and cancer, while its impact in anabolism is similar in the two conditions. Reductive stress, driven by the elevated NADH/NAD+ ratio, promotes the biosynthesis of nucleotides, glucose, and fatty acids (Fig. 2), which is essential for the proliferation of cancer cells and stem cells by synthesis of building blocks in cell proliferation. [Display omitted] [ABSTRACT FROM AUTHOR]

Reductive stress, characterized by rising level of NADH (nicotinamide adenine dinucleotide) for a status of NADH/NAD+ ratio elevation, has been reported in obesity and cancer. However, the mechanism and significance of reductive stress remain to be established in obesity. This perspective is prepared to address the issue with new insights published recently. NADH is used in production of NADPH, glutathione, ATP and heat in the classical biochemistry. In obesity, elevation of NADH/NAD+ ratio, likely from overproduction due to substrate overloading, has been found in the liver for insulin resistance and gluconeogenesis. New evidence demonstrates that the elevation may induce lipogenesis, purine biosynthesis and gluconeogenesis through activation of transcription factors of ChREBP and NRF2. In cancer cells, NADH/NAD+ elevation under the Warburg effect is primarily derived from decreased NADH consumption in the mitochondrial respiration. Alternatively, NRF2 overactivation from gene mutation represents another mechanism of NADH/NAD+ elevation from NADH production in the cancer cells. The elevation is required for quick proliferation of cancer cells through induction of biosynthesis of the essential molecules. It appears that the causes of reductive stress are different between obesity and cancer, while its impact in anabolism is similar in the two conditions.

Abstract Background The relationship between hepatocellular carcinoma (HCC) metastasis and cancer metabolism reprogramming is becoming increasingly evident. Ubiquitin-specific protease 11 (USP11), a member of the deubiquitinating enzyme family, has been linked to various cancer-related processes. While USP11 is known to promote HCC metastasis and proliferation, the precise mechanisms, especially those related to cancer metabolism, remain unclear. Methods Through mass spectrometry, co-immunoprecipitation, immunofluorescence, and ubiquitination assays, we identified USP11 as the key deubiquitinase for SREBF1.Lipogenesis was evaluated using Oil Red O and Nile Red staining, along with the detection of triglycerides and cholesterol. To assess HCC cell proliferation, migration, and invasion in vitro, Transwell assays, EDU, colony formation, and CCK-8 were conducted. Xenograft models in nude mice were developed to verify the role of the USP11/SREBF1 axis in lipogenesis and tumor growth in vivo. Results USP11 directly interacts with SREBF1, and its silencing leads to the disruption of SREBF1 stabilization through K48-linked deubiquitination and degradation. Importantly, the truncated mutant USP11 (503–938 aa) interacts with the truncated mutant SREBF1 (569–1147aa), with K1151 playing a crucial role in this interaction. Higher levels of USP11 enhance lipogenesis, proliferation, and metastasis in HCC cells. Importantly, the knockdown of SREBF1 weakened the effects of USP11 in enhancing lipogenesis and tumorigenesis. Futhermore, the elevated expression of USP11 and SREBF1 in HCC tissue serves as an indicator of poor prognosis in HCC patients. Conclusions In summary, our study reveals that USP11 promotes HCC proliferation and metastasis through SREBF1-induced lipogenesis. These findings provide a foundation for novel therapies targeting lipid metabolism in HCC.

We investigated the effect of purified withanolides and extracts derived from Ashwagandha on steatosis, the abnormal accumulation of fat that can lead to non-alcoholic fatty liver disease (NAFLD). Collaborator of ARF (CARF, also known as CDKN2AIP, a protein that regulates hepatic lipid metabolism, fat buildup, and liver damage) was used as an indicator. Six withanolides (Withaferin A, Withanone, Withanolide B, Withanoside IV, Withanoside V, and Withanostraminolide-12 deoxy) reversed the decrease in CARF caused by exposure to free fatty acids (FFAs) in liver-derived cells (HepG2 hepatocytes). After analyzing the effects of these withanolides on CARF mRNA and protein levels, FFA accumulation, protein aggregation, and oxidative and DNA damage stresses, we selected Withaferin A and Withanone for molecular analyses. Using the palmitic-acid-induced fatty acid accumulation stress model in Huh7 cells, we found a significant reduction in the activity of the key regulators of lipogenesis pathways, including sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid synthase (FASN), and peroxisome proliferator-activated receptors (PPARγ and PPARα). This in vitro study suggests that low, non-toxic doses of Withaferin A, Withanone, or Ashwagandha extracts containing these withanolides possess anti-steatosis and antioxidative-stress properties. Further in vivo and clinical studies are required to investigate the therapeutic potential of these Ashwagandha-derived bioactive ingredients for NAFLD. [ABSTRACT FROM AUTHOR]

This study focused on evaluating the anti-obesity effects of an extract from Ampelopsis grossedentata (Hand.-Mazz.) W. T. Wang, also known as vine tea, in mature adipocytes and high-fat diet-induced obese mice. Vine tea extract (VTE) effectively decreased lipid accumulation in mature adipocytes without cytotoxicity, as confirmed by the regulation of several factors associated with adipogenesis, lipogenesis, or lipolysis. Subsequently, in a 12-week experiment with obese mice, oral VTE administration significantly reduced body weight gain induced with high-fat diet intake. Au-topsy findings showed reduced fat accumulation in various areas without liver damage. The VTE-administered group showed lower serum LDL levels, while increasing HDL, than the high-fat diet-administered group. Analysis of adipose tissue biomarkers indicated VTE's ability to inhibit adipogenesis and lipogenesis, promote lipolysis, and regulate energy metabolism, contributing to reduced adiposity induced by the consumption of a high-fat diet. [ABSTRACT FROM AUTHOR]

Background: The relationship between hepatocellular carcinoma (HCC) metastasis and cancer metabolism reprogramming is becoming increasingly evident. Ubiquitin-specific protease 11 (USP11), a member of the deubiquitinating enzyme family, has been linked to various cancer-related processes. While USP11 is known to promote HCC metastasis and proliferation, the precise mechanisms, especially those related to cancer metabolism, remain unclear. Methods: Through mass spectrometry, co-immunoprecipitation, immunofluorescence, and ubiquitination assays, we identified USP11 as the key deubiquitinase for SREBF1.Lipogenesis was evaluated using Oil Red O and Nile Red staining, along with the detection of triglycerides and cholesterol. To assess HCC cell proliferation, migration, and invasion in vitro, Transwell assays, EDU, colony formation, and CCK-8 were conducted. Xenograft models in nude mice were developed to verify the role of the USP11/SREBF1 axis in lipogenesis and tumor growth in vivo. Results: USP11 directly interacts with SREBF1, and its silencing leads to the disruption of SREBF1 stabilization through K48-linked deubiquitination and degradation. Importantly, the truncated mutant USP11 (503–938 aa) interacts with the truncated mutant SREBF1 (569–1147aa), with K1151 playing a crucial role in this interaction. Higher levels of USP11 enhance lipogenesis, proliferation, and metastasis in HCC cells. Importantly, the knockdown of SREBF1 weakened the effects of USP11 in enhancing lipogenesis and tumorigenesis. Futhermore, the elevated expression of USP11 and SREBF1 in HCC tissue serves as an indicator of poor prognosis in HCC patients. Conclusions: In summary, our study reveals that USP11 promotes HCC proliferation and metastasis through SREBF1-induced lipogenesis. These findings provide a foundation for novel therapies targeting lipid metabolism in HCC. [ABSTRACT FROM AUTHOR]

Obesity is a global health concern associated with severe diseases, including atherosclerosis, osteoarthritis, coronary artery disease, and cerebrovascular disorders. These conditions pose significant risks such as restricted blood flow, coronary heart disease, and mortality. Fatty acid synthase (FAS), a key enzyme in lipogenesis, plays a pivotal role in fat accumulation and is a primary target for therapeutic intervention. Orlistat, a widely used drug that targets and inhibits fatty acid synthase activity to treat obesity; however, prolonged use may result in unintended health issues. This study aimed to identify natural compounds from Diospyros ebenum (Ceylon ebony) and Oldenlandia umbellata (chay root) that inhibit fatty acid synthase. Through comprehensive in silico analyses, including ADMET studies, toxicity profiling, pharmacophore analysis, ligand-receptor interactions, and molecular simulations, we found phytochemicals from these plants to be non-toxic with favourable pharmacological properties. Molecular interaction studies demonstrated efficient binding to the fatty acid synthase site, suggesting potential for inhibiting enzyme activity and reducing fat accumulation. In conclusion, Oldenlandia umbellata exhibited greater efficacy compared to Diospyros ebenum, suggesting its ability as a promising source of anti-obesity agents. These findings offer valuable insights for further experimental investigation. [ABSTRACT FROM AUTHOR]

Omega fatty acids are important for human health. They are traditionally extracted from animals or plants but can be alternatively produced using oleaginous yeast. Current efforts are producing yeast strains with similar fatty acid distributions and powerful lipogenesis capacity. The next step is to further make the process more competitive. [ABSTRACT FROM AUTHOR]

Increased de novo lipogenesis is a hallmark of metabolic dysfunction-associated steatotic liver disease (MASLD) in obesity, but the macronutrient carbon source for over half of hepatic fatty acid synthesis remains undetermined. Here, we discover that dietary protein, rather than carbohydrates or fat, is the primary nutritional risk factor for MASLD in humans. Consistently, ex vivo tracing studies identify amino acids as a major carbon supplier for the tricarboxylic acid (TCA) cycle and lipogenesis in isolated mouse hepatocytes. In vivo , dietary amino acids are twice as efficient as glucose in fueling hepatic fatty acid synthesis. The onset of obesity further drives amino acids into fatty acid synthesis through reductive carboxylation, while genetic and chemical interventions that divert amino acid carbon away from lipogenesis alleviate hepatic steatosis. Finally, low-protein diets (LPDs) not only prevent body weight gain in obese mice but also reduce hepatic lipid accumulation and liver damage. Together, this study uncovers the significant role of amino acids in hepatic lipogenesis and suggests a previously unappreciated nutritional intervention target for MASLD. [Display omitted] • High dietary protein intake increases the risk of MASLD/MASH • Amino acid-derived carbons readily fuel the TCA cycle and fatty acid synthesis in liver • Reducing protein intake or rerouting amino acid catabolism improves hepatic steatosis The macronutrient driver of hepatic steatosis and metabolic dysfunction-associated steatotic liver disease (MASLD) has not been fully defined. Liao et al. identify high dietary protein consumption as a significant risk factor for MASLD/MASH in the NHANES study. The authors further establish amino acids as a prime substrate fueling hepatic lipogenesis, as demonstrated through isotope tracing and a series of chemical, genetic, and dietary intervention studies. [ABSTRACT FROM AUTHOR]

Triterpenoids have been identified as potential novel lipid‐lowering drugs for the treatment of hypertriglyceridemia. This study investigated the potential antilipogenic and/or antilipolytic effects of two triterpenoids (ARM‐2 and RA‐5) isolated from the stem bark of Protorhus longifolia (Benrh.) Engl. Employing a combination of in silico predictions and in vitro assays, the interactions between these triterpenoids and key proteins involved in lipogenesis and lipolysis were investigated. In silico molecular docking analysis predicted a favourable binding affinity of both triterpenoids to PPARγ, SREBP‐1, and AMPK, with lower binding affinity to C/EBPα, pancreatic lipase, and hormone‐sensitive lipase (HSL). Both triterpenoids exhibited in vitro inhibition of pancreatic lipase with Ki and IC50 values ranging from 28.7 to 52.9 μM and 27.6 to 35.8 μM, respectively. Total and neutral lipid accumulation in differentiated 3T3‐L1 adipocytes and the oleic acid–induced HepG2 cell model was inhibited, with ARM‐2 showing better inhibition than RA‐5. In the HepG2 model, the inhibitory activity of the two triterpenoids (at 25 and 100 μM) was comparable to 50 μM lovastatin, although the latter was cytotoxic, whereas both ARM‐2 and RA‐2 lacked cytotoxicity. Associated gene expression was similar to the effect of simvastatin where the expression of SREBP‐1, PPARγ, C/EBPα, and HSL was reduced and that of AMPK was unchanged. In vitro studies confirmed that ARM‐2 and RA‐5 also inhibited adipocyte lipolysis, where the reduction in glycerol release by 25 and 100 μM was similar to 50 μM lovastatin and simvastatin. This study identifies that the triterpenoids, ARM‐2 and RA‐5, have the potential to modulate lipogenesis and lipolysis. [ABSTRACT FROM AUTHOR]

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

In mammals, the maintenance of energy homeostasis relies on complex mechanisms requiring tight synchronization between peripheral organs and the brain. Thyroid hormones (THs), through their pleiotropic actions, play a central role in these regulations. Hypothyroidism, which is characterized by low circulating TH levels, slows down the metabolism, which leads to a reduction in energy expenditure as well as in lipid and glucose metabolism. The objective of this study was to evaluate whether the metabolic deregulations induced by hypothyroidism could be avoided through regulatory mechanisms involved in metabolic flexibility. To this end, the response to induced hypothyroidism was compared in males from two mouse strains, the wild-derived WSB/EiJ mouse strain characterized by a diet-induced obesity (DIO) resistance due to its high metabolic flexibility phenotype and C57BL/6J mice, which are prone to DIO. The results show that propylthiouracil (PTU)-induced hypothyroidism led to metabolic deregulations, particularly a reduction in hepatic lipid synthesis in both strains. Furthermore, in contrast to the C57BL/6J mice, the WSB/EiJ mice were resistant to the metabolic dysregulations induced by hypothyroidism, mainly through enhanced lipid metabolism in their adipose tissue. Indeed, WSB/EiJ mice compensated for the decrease in hepatic lipid synthesis by mobilizing lipid reserves from white adipose tissue. Gene expression analysis revealed that hypothyroidism stimulated the hypothalamic orexigenic circuit in both strains, but there was unchanged melanocortin 4 receptor (Mc4r) and leptin receptor (LepR) expression in the hypothyroid WSB/EiJ mice strain, which reflects their adaptability to maintain their body weight, in contrast to C57BL/6J mice. Thus, this study showed that WSB/EiJ male mice displayed a resistance to the metabolic dysregulations induced by hypothyroidism through compensatory mechanisms. This highlights the importance of metabolic flexibility in the ability to adapt to disturbed circulating TH levels. [ABSTRACT FROM AUTHOR]

This study investigated the antiobesity effects of black ginger extract (BGE) in high-fat diet (HFD)-induced obese mice. Mice were divided into six groups: normal diet control (NC, AIN-93G normal diet), 60% HFD control (HFD), HFD containing metformin at 250 mg/kg b.w. (Met, positive control), and HFD containing BGE at 5, 10, or 20 mg/kg b.w. for 15 weeks. BGE administration significantly prevented HFD-induced increases in weight gain, organ weight, and adipose tissue mass. Furthermore, it resulted in decreased adipogenesis and lipogenesis-related factors, including phosphorylated mitogen-activated protein kinase, peroxisome proliferator-activated receptor gamma, CCAAT/enhancer-binding proteins, sterol regulatory element-binding protein 1, phosphorylated cAMP response element-binding protein, glucose-6-phosphate dehydrogenase, fatty acid synthase, dephosphorylated ATP-citrate lyase, dephosphorylated acetyl-CoA carboxylase, and lipoprotein lipase, in white adipose tissues. Moreover, BGE administration enhanced lipolysis in white adipose tissue, as evidenced by elevated levels of adipose triglyceride lipase, phosphorylated hormone-sensitive lipase, and protein kinase A, along with reduced levels of perilipin and phosphodiesterase 3B. BGE induced thermogenesis in brown adipose tissues, as reflected by the increased expression of AMP-activated protein kinase, uncoupling protein 1, and carnitine palmitoyltransferase 1 and decreased levels of fatty acid-binding protein 4. In conclusion, this study provides comprehensive evidence supporting the antiobesity effects of BGE, elucidating the underlying molecular mechanisms involved in preventing weight gain, suppressing adipogenesis, promoting lipolysis, and stimulating thermogenesis. These findings suggest the potential therapeutic utility of BGE in combating obesity and associated metabolic disorders (KHGASP-2023-034). [ABSTRACT FROM AUTHOR]

Macadamia oil has high concentrations of oleic and palmitoleic fatty acids, which can increase tissue sensitivity to insulin, improving glucose absorption efficiency, and reducing lipogenesis through gene modulation. The objective of this study was to evaluate the effects of macadamia oil associated with vitamin E supplementation on performance, blood parameters, meat quality and sensory characteristics, meat fatty acid profile, and expression of genes associated with lipid metabolism in grazing lambs. The experimental treatments were control diet (Control), Control + 0.1% of body weight of macadamia oil (MO), MO + 745 IU of vitamin E/dry matter (MOVE). Macadamia oil improved feed efficiency, reflecting a lower dry matter intake, as the average daily weight gain did not differ from Control. Meat quality parameters were not affected by macadamia oil or vitamin E supplementation. Supplementation with macadamia oil improved meat appearance, flavor, and overall liking. Supplementation with macadamia oil provided a higher proportion of C18:3 n3 and a lower proportion of CLA. The expression of SREBP-1c, PPAR-α, SCD1, and ELOVL6 genes were not modified with the supplementation of macadamia oil and vitamin E. In conclusion, supplementation with macadamia oil improves feed efficiency and meat quality; and the inclusion of 745 IU of vitamin E/kg of dry matter for grazing lambs reduces 36% of lipid oxidation of the meat. [ABSTRACT FROM AUTHOR]

Fatty acid‐binding protein 1 (FABP1) plays an important role in regulating fatty acid metabolism in liver, which is a potential therapeutic target for diseases such as non‐alcoholic fatty liver disease (NAFLD). However, the underlying mechanisms are not well defined. Using complementary experimental models, we discovered FABP1 induction in hepatocytes as a primary mediator of lipogenesis when exposed to fatty acids, especially saturated fatty acids (SFAs). In the feeding trial, palm oil led to excess lipid accumulation in the liver of large yellow croaker (Larimichthys crocea), accompanied by significant induction of FABP1. In cultured cells, palmitic acid (PA), a kind of SFA, triggered the fabp1 expression and increased triglyceride (TG) contents. Knockdown of FABP1 dampened PA‐induced TG accumulation through mitigated lipogenesis. The overexpression of FABP1 showed the opposite result. Furthermore, the inactivation of FABP1 led to induction in insulin‐induced gene 1 (INSIG1) expression, which attenuated the processing of sterol regulatory element‐binding protein 1 (SREBP1) by down‐regulating the nuclear‐localized SREBP1. These results revealed a previously unrecognized function of FABP1 in response to PA, providing additional evidence for targeting FABP1 in the treatment of NAFLD caused by SFA. [ABSTRACT FROM AUTHOR]

Non-alcoholic fatty acid disease (NAFLD) is caused by a build-up of fat in the liver, inducing local inflammation and fibrosis. We evaluated the effects of probiotic lactic acid-generating bacteria (LAB) derived from a traditional fermented beverage in a mouse model of NAFLD. The LAB isolated from this traditional Korean beverage were screened using the human hepatic cell line HepG2, and Lactocaseibacillus paracasei HY7207 (HY7207), which was the most effective inhibitor of fat accumulation, was selected for further study. HY7207 showed stable productivity in industrial-scale culture. Whole-genome sequencing of HY7207 revealed that the genome was 2.88 Mbp long, with 46.43% GC contents and 2778 predicted protein-coding DNA sequences (CDSs). HY7207 reduced the expression of lipogenesis and hepatic apoptosis-related genes in HepG2 cells treated with palmitic acid. Furthermore, the administration of 109 CFU/kg/day of HY7207 for 8 weeks to mice fed an NAFLD-inducing diet improved their physiologic and serum biochemical parameters and ameliorated their hepatic steatosis. In addition, HY7207 reduced the hepatic expression of genes important for lipogenesis (Srebp1c, Fasn, C/ebpa, Pparg, and Acaca), inflammation (Tnf, Il1b, and Ccl2), and fibrosis (Col1a1, Tgfb1, and Timp1). Finally, HY7207 affected the expression of the apoptosis-related genes Bax (encoding Bcl2 associated X, an apoptosis regulator) and Bcl2 (encoding B-cell lymphoma protein 2) in the liver. These data suggest that HY7207 consumption ameliorates NAFLD in mice through effects on liver steatosis, inflammation, fibrosis, and hepatic apoptosis. Thus, L. paracasei HY7207 may be suitable for use as a functional food supplement for patients with NAFLD. [ABSTRACT FROM AUTHOR]

As a potential endocrine-disrupting chemical, bisphenol F (BPF) may cause nonalcoholic fatty liver disease (NAFLD)-like changes, but the mechanisms under its pathogenesis as well as the intervention strategies remain unclear. Using the electron microscopy technology, along with LipidTOX Deep Red neutral and Bodipy 493/503 staining assays, we observed that BPF treatment elicited a striking accumulation of lipid droplets in HepG2 cells, accompanied by an increased total level of triglycerides. At the molecular level, the lipogenesis-associated mRNAs and proteins, including acetyl-CoA carboxylase, fatty acid synthase, stearoyl-CoA desaturase-1, peroxisome proliferator-activated receptor gamma, and CCAAT-enhancer-binding proteins, increased significantly via the AMP-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) signaling regulation in both in vitro and in vivo studies. Furthermore, the immunofluorescence results also showed the robust lipogenesis induced by BPF, evident in its ability to promote the translocation of sterol regulatory elementbinding protein-1c from the cytoplasm to the nuclei. To investigate the intervention strategies for BPF-induced NAFLD-like changes, we demonstrated that bellidifolin, isolated and purified from Swertia chirayita, significantly attenuated BPF-induced lipid droplet deposition in HepG2 cells and NAFLD-like changes in mice by blocking the expression of lipogenesis-associated proteins. Therefore, the present study elucidates the mechanisms underlying the BPF-induced lipid accumulation in HepG2 cells, while also highlighting the potential of bellidifolin to mitigate BPF-induced NAFLD-like changes. [ABSTRACT FROM AUTHOR]

Simple Summary: Porcine reproductive and respiratory syndrome (PRRS) caused by PRRS virus (PRRSV) leads to considerable economic losses for the global pig industry. Investigating PRRSV–host interactions is important for understanding PRRSV pathogenesis and developing antiviral strategies. This study focuses on the post-transcriptional regulation of let-7f-5p in response to PPRSV infection. Lipids play a key role in the replication cycle of PRRSV. We found that let-7f-5p directly targets the master lipid metabolism regulator SREBP2 and influences the expression of lipogenesis genes, which provide a novel target for PRRSV antiviral therapy. Porcine reproductive and respiratory syndrome (PRRS) has caused substantial damage to the pig industry. MicroRNAs (miRNAs) were found to play crucial roles in modulating the pathogenesis of PRRS virus (PRRSV). In the present study, we revealed that PRRSV induced let-7f-5p to influence lipid metabolism to regulate PRRSV pathogenesis. A transcriptome analysis of PRRSV-infected PK15CD163 cells transfected with let-7f-5p mimics or negative control (NC) generated 1718 differentially expressed genes, which were primarily associated with lipid metabolism processes. Furthermore, the master regulator of lipogenesis SREBP2 was found to be directly targeted by let-7f-5p using a dual-luciferase reporter system and Western blotting. The findings demonstrate that let-7f-5p modulates lipogenesis by targeting SREBP2, providing novel insights into miRNA-mediated PRRSV pathogenesis and offering a potential antiviral therapeutic target. [ABSTRACT FROM AUTHOR]

Cancer is characterized by metabolic reprogramming in cancer cells, which is crucial for tumorigenesis. The highly deregulated chromatin remodeler MORC2 contributes to cell proliferation, invasion, migration, DNA repair, and chemoresistance. MORC2 also plays a key role in metabolic reprogramming, including lipogenesis, glucose, and glutamine metabolism. A recent study showed that MORC2-regulated glucose metabolism affects the expression of E-cadherin, a crucial protein in the epithelial-to-mesenchymal transition. This review discusses recent developments in MORC2 regulated cancer cell metabolism and its role in cancer progression. [ABSTRACT FROM AUTHOR]

Abstract Aberrant upregulation of hepatic lipogenesis induced by chronic and excessive alcohol consumption is a critical driver of the progression of alcohol‐associated liver disease (ALD), however, no effective approaches inhibiting lipogenesis are currently available for treating ALD patients. Moreover, little is known about whether and how nonethanol ingredients in alcoholic beverages regulate the pathogenesis of ALD. Here the discovery of a small molecule that activates the production and secretion of fibroblast growth factor 21 (FGF21) is reported. It is shown that the activator ethyl lactate, a nonethanol ingredient found in distilled liquors, ameliorates alcoholic hepatosteatosis, inflammation and acute‐on‐chronic liver injury by stimulating FGF21. In response to chronic‐plus‐binge ethanol feeding or fasting, ethyl lactate mimics lipogenesis lowering effects by stimulating FGF21 production through the NAD+‐dependent deacetylase sirtuin 1 (SIRT1) signaling pathway. These ethyl lactate‐mediated beneficial effects are abolished by inhibition of SIRT1 through injection of EX527. Importantly, FGF21 deficiency in hepatocytes blocks the downregulation of lipogenesis by ethyl lactate and exacerbates alcoholic steatosis, inflammation and liver injury. The regulatory mechanism is discussed during the pathophysiological conditions and suggests new lines of research into the therapeutic use of a foodborne small molecule ethyl lactate.