Hyperlipidemic effects of dietary saturated fats mediated through PGC-1beta coactivation of SREBP

Mechanisms of action of Fucus vesiculosus-derived fucoidan on improving dyslipidemia in New Zealand rabbits fed a high-fat diet

Dyslipidemia is a major contributor to various diseases, including atherosclerotic cardiovascular disease and obesity. Treatment strategies for dyslipidemia continue to evolve as our understanding of this metabolic disorder and potential therapeutic candidates advance. Notably, fucoidan demonstrates promising effects in ameliorating dyslipidemia in rodents, although their lipid metabolism differs significantly from humans. This study, investigates the lipid-regulatory effects of Fucus vesiculosus-derived fucoidan (FvF) and elucidates the underlying mechanisms of action using New Zealand rabbits fed a high-fat diet, whose lipid profiles closely resemble those of patients with dyslipidemia. The results demonstrate that FvF intervention ameliorates dyslipidemia and lipid deposition in a dose-dependent manner. Mechanistically, FvF intervention modulates the expression levels of multiple molecules involved in lipid transport, fatty acid synthesis and beta-oxidation, and redox balance, as revealed by quantitative reverse transcription polymerase chain reaction, western blotting, and proteomic analysis. This study is the first to report that FvF, consisting of alternating [→4)-α-L-Fucp(1 → 3)-α-L-Fucp(1→] glycosyls ameliorates dyslipidemia by directly modulating lipid metabolism and indirectly attenuating oxidative stress. These findings suggest that FvF holds significant potential as a candidate for the treatment of lipid disorder-related diseases.

Mitonuclear Communication in Stem Cell Function

Mitochondria perform multiple functions within the cell, including the production of ATP and a great deal of metabolic intermediates, while also contributing to the cellular stress response. The majority of mitochondrial proteins are encoded by nuclear genomes, highlighting the importance of mitonuclear communication for sustaining mitochondrial homeostasis and functional. As a crucial part of the intracellular signalling network, mitochondria can impact stem cell fate determinations. Considering the essential function of stem cells in tissue maintenance, regeneration and aging, it is important to understand how mitochondria influence stem cell fate. This review explores the significant roles of mitonuclear communication and mitochondrial proteostasis, highlighting their influence on stem cells. We also examine how mitonuclear interactions contribute to cellular homeostasis, stem cell therapies, and the potential for extending lifespan.

Protective effects and mechanisms of quercetin in animal models of hyperuricemia: A systematic review and meta-analysis

Quercetin, a prevalent natural flavonoid found in various medicinal plants, including Dendrobium officinale Kimura & Migo, has garnered attention for its potential health benefits. However, foundational animal studies investigating the effects of quercetin on lowering uric acid levels remain insufficiently established, and the number of related clinical studies is limited. This scarcity hinders the practical application of quercetin in managing hyperuricemia. We systematically searched for preclinical studies published by December 2024 in nine databases, such as PubMed, Web of Science, and Embase. The results of our meta-analysis showed that, compared with the model group, quercetin not only effectively alleviated the pathological injury of the kidney and liver and improved the renal function indexes in the animal model of hyperuricemia but also played a role in lowering uric acid by modulating multiple signaling pathways such as oxidative stress, lipid metabolism, and transporter proteins. Quercetin showed a more substantial effect in decreasing serum creatinine levels (SMD = -4.29, 95 % CI [-6.48, -2.10], P = 0.0001), blood urea nitrogen levels (SMD = -3.08, 95 % CI [-4.80, -1.35], P = 0.0005), and Up-regulate organic anion transporter 1 mRNA expression levels (SMD = 2.72, 95 %CI [0.45, 4.99], P = 0.02) compared to the positive control group. Sensitivity analyses confirmed the stability of the results, while the subgroup analysis indicates that the treatment course may be the main source of heterogeneity. The results of the Dose-efficacy analysis suggested that quercetin had a more substantial protective effect against hyperuricemia at a gavage dose of 100-200 mg/kg. However, to more accurately assess the effects of quercetin on hyperuricemia, it is essential to conduct additional high-quality, large-scale animal trials to validate our findings.

Role of PGC-1α in the proliferation and metastasis of malignant tumors

Malignant tumors are among the major diseases threatening human survival in the world, and advancements in medical technology have led to a steady increase in their detection rates worldwide. Despite unique clinical presentations across the spectrum of malignancies, treatment modalities generally adhere to common strategies, encompassing primarily surgical intervention, radiation therapy, chemotherapy, and targeted treatments. Uncovering the genetic elements contributing to cancer cell proliferation, metastasis, and drug resistance remains a pivotal pursuit in the development of novel targeted therapeutics. Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PPARGC1A/PGC-1α) is a transcriptional coactivator that influences most cellular metabolic pathways. Its aberrant expression is associated with numerous chronic diseases, including diabetes, heart failure, neurodegenerative disorders, and cancer development. This study primarily discusses the structure, physiological functions, regulatory mechanisms, and research advancement concerning the role of PGC-1α in the proliferation and metastasis of malignant tumors. Targeting PGC-1α and its related regulatory pathways for therapeutic interventions holds promise in facilitating precise and individualized oncological treatments. This approach is expected to counteract drug resistance in patients with cancer and offer a novel direction for the treatment of malignant tumors.

Myeloid PGC1β attenuates high-fat-diet induced inflammation via mitochondrial fission/mtDNA/Nlrp3 pathway

Peroxisome proliferator-activated receptor gamma coactivators 1β (PGC1β) is essential in mitochondrial oxidative phosphorylation and alternative macrophages activation. To determine the contribution of PGC1β in obesity induced inflammation, Ppargc1b (PGC1β coding gene) myeloid conditional knockout mice (cKO) were fed with high fat diet (HFD) to examine the following effects. We found that HFD-fed cKO mice gained more fat with increased serum triglyceride (TG), low density lipoprotein (LDL), adiponectin, and leptin. Adipogenesis was stimulated while lipolysis was retarded in HFD-fed cKO mice adipose. Gluconeogenesis, lipogenesis, and fatty acid uptake were provoked while lipolysis was inhibited in HFD-fed cKO liver. Serum alanine transaminase (ALT) level, indicating fatty liver, also increased. Inflammatory cytokine including tumor necrosis factor-α (TNF-α), IL-1β, and IL-6 was elevated in cKO mice, accompanied with glucose intolerant and insulin resistance. Energy expenditure was decreased in HFD-fed cKO mice. Further evidence showed that cKO macrophages were prone to repolarize into M1 inflammatory type in vitro. In addition to mitochondrial biogenesis and oxidative respiration, PGC1β also modulated mitochondrial fission and cytosolic mitochondrial DNA (mtDNA) release, contributing to NLR family pyrin domain containing 3 (Nlrp3) inflammasome priming and activation. Treatment of mitochondrial fission inhibitor abolished the increased mRNA levels of Nlrp3 and IL-1β induced by PGC1β depletion. Nlrp3 knockdown restored the induced IL-1β mRNA expression by PGC1β deficiency. Myeloid PGC1β regulated adipocyte adipogenesis and lipolysis. PGC1β loss-of-function and mtDNA abundance correlated with obesity and diabetes. These observations uncovered the protective role of PGC1β against obesity induced systemic inflammation. Enhancing myeloid PGC1β function may be a potential strategy for the intervention of obesity and related diseases.

Diet predisposes to pancreatic cancer through cellular nutrient sensing pathways

Pancreatic cancer is a lethal disease with limited effective treatments. A deeper understanding of its molecular mechanisms is crucial to reduce incidence and mortality. Epidemiological evidence suggests a link between diet and disease risk, though dietary recommendations for at-risk individuals remain debated. Here, we propose that cell-intrinsic nutrient sensing pathways respond to specific diet-derived cues to facilitate oncogenic transformation of pancreatic epithelial cells. This review explores how diet influences pancreatic cancer predisposition through nutrient sensing and downstream consequences for (pre-)cancer cell biology. We also examine experimental evidence connecting specific food intake to pancreatic cancer progression, highlighting nutrient sensing as a promising target for therapeutic development to mitigate disease risk.

Association between hypercholesterolemia and isolated and simultaneous consumption of ultra-processed foods in older adults

Background

Consumption of ultra-processed foods (UPFs) is a risk factor for several cardiovascular diseases and mortality, with potential physiological mechanisms including elevated serum cholesterol levels.

Objectives

To analyze the association between hypercholesterolemia and the isolated and simultaneous consumption of UPFs in older adults.

Methods

This is a cross-sectional epidemiological study conducted with 1322 Brazilian older adults (mean age of 70.4 years; 55.0% females) from the state of Roraima. The data was obtained from the Department of Epidemiological Surveillance of the State of Roraima. Hypercholesterolemia was diagnosed based on nosology criteria. Food consumption patterns were assessed using a nationally standardized instrument comprising four categories of UPFs. Binary logistic regression models were employed to explore potential associations.

Results

The prevalence of hypercholesterolemia was high (54.4%, 95% CI 51.7-56.6). While the simultaneous consumption of all UPFs types was lower (15.2%), over half of the older adults reported consuming at least one type of UPFs (71.8%). Isolated consumption of UPFs was associated with approximately twice the odds of hypercholesterolemia. Older adults who consumed two (OR 1.75, 95% CI 1.26-2.43), three (OR 2.28, 95% CI 1.58-3.29), or all four types of UPF (OR 6.65, 95% CI 4.35-9.44) had a higher likelihood of having hypercholesterolemia.

Conclusions

Isolated consumption of UPFs is a risk factor for hypercholesterolemia, which can increase up to sixfold when older adults consume multiple UPFs simultaneously. Prioritizing nutritional education and raising awareness regarding the reduction of UPFs consumption is crucial.

UCP2 and pancreatic cancer: conscious uncoupling for therapeutic effect

Pancreatic cancer has an exaggerated dependence on mitochondrial metabolism, but methods to specifically target the mitochondria without off target effects in normal tissues that rely on these organelles is a significant challenge. The mitochondrial uncoupling protein 2 (UCP2) has potential as a cancer-specific drug target, and thus, we will review the known biology of UCP2 and discuss its potential role in the pathobiology and future therapy of pancreatic cancer.

Regulation and targeting of SREBP-1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an increasing burden on global public health and is associated with enhanced lipogenesis, fatty acid uptake, and lipid metabolic reprogramming. De novo lipogenesis is under the control of the transcription factor sterol regulatory element-binding protein 1 (SREBP-1) and essentially contributes to HCC progression. Here, we summarize the current knowledge on the regulation of SREBP-1 isoforms in HCC based on cellular, animal, and clinical data. Specifically, we (i) address the overarching mechanisms for regulating SREBP-1 transcription, proteolytic processing, nuclear stability, and transactivation and (ii) critically discuss their impact on HCC, taking into account (iii) insights from pharmacological approaches. Emphasis is placed on cross-talk with the phosphatidylinositol-3-kinase (PI3K)-protein kinase B (Akt)-mechanistic target of rapamycin (mTOR) axis, AMP-activated protein kinase (AMPK), protein kinase A (PKA), and other kinases that directly phosphorylate SREBP-1; transcription factors, such as liver X receptor (LXR), peroxisome proliferator-activated receptors (PPARs), proliferator-activated receptor γ co-activator 1 (PGC-1), signal transducers and activators of transcription (STATs), and Myc; epigenetic mechanisms; post-translational modifications of SREBP-1; and SREBP-1-regulatory metabolites such as oxysterols and polyunsaturated fatty acids. By carefully scrutinizing the role of SREBP-1 in HCC development, progression, metastasis, and therapy resistance, we shed light on the potential of SREBP-1-targeting strategies in HCC prevention and treatment.

Antagonism of let-7c reduces atherosclerosis and macrophage lipid accumulation by promoting PGC-1α/LXRα/ABCA1/G1 pathway

Changes in circulating let-7c were significantly associated with the alter in lipid profile, but its role in intracellular lipid metabolism remains unknown. This work was conducted to explore the effects of let-7c on the lipid accumulation in macrophages and uncover the underlying mechanism. Our results showed that let-7c inhibition relieved atherosclerosis progression in apoE-/- mice. In ox-LDL-treatment macrophages, let-7c knockdown suppressed lipid accumulation but does no affect cholesterol intake. Consistent with this, overexpression of let-7c promoted lipid accumulation by reducing the expression of LXRα and ABCA1/G1. Mechanistically, let-7c targeted PGC-1α to repress the expression of LXRα and ABCA1/G1, thereby regulating cholesterol homeostasis in macrophages. Taken together, these findings suggest that antagonism of let-7c reduces atherosclerosis and macrophage lipid accumulation through the PGC-1α/LXRα/ABCA1/G1 axis.

Fatty Acids and Their Lipogenic Enzymes in Anorexia Nervosa Clinical Subtypes

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.

Functional overlap between the mammalian Sar1a and Sar1b paralogs in vivo

Proteins carrying a signal peptide and/or a transmembrane domain enter the intracellular secretory pathway at the endoplasmic reticulum (ER) and are transported to the Golgi apparatus via COPII vesicles or tubules. SAR1 initiates COPII coat assembly by recruiting other coat proteins to the ER membrane. Mammalian genomes encode two SAR1 paralogs, SAR1A and SAR1B. While these paralogs exhibit ~90% amino acid sequence identity, it is unknown whether they perform distinct or overlapping functions in vivo. We now report that genetic inactivation of Sar1a in mice results in lethality during midembryogenesis. We also confirm previous reports that complete deficiency of murine Sar1b results in perinatal lethality. In contrast, we demonstrate that deletion of Sar1b restricted to hepatocytes is compatible with survival, though resulting in hypocholesterolemia that can be rescued by adenovirus-mediated overexpression of either SAR1A or SAR1B. To further examine the in vivo function of these two paralogs, we genetically engineered mice with the Sar1a coding sequence replacing that of Sar1b at the endogenous Sar1b locus. Mice homozygous for this allele survive to adulthood and are phenotypically normal, demonstrating complete or near-complete overlap in function between the two SAR1 protein paralogs in mice. These data also suggest upregulation of SAR1A gene expression as a potential approach for the treatment of SAR1B deficiency (chylomicron retention disease) in humans.

Anthocyanins: Potential phytochemical candidates for the amelioration of non-alcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is described by too much hepatic fat deposition causing steatosis, which further develops into nonalcoholic steatohepatitis (NASH), defined by necroinflammation and fibrosis, progressing further to hepatic cirrhosis, hepatocellular carcinoma, and liver failure. NAFLD is linked to different aspects of the metabolic syndrome like obesity, insulin resistance, hypertension, and dyslipidemia, and its pathogenesis involves several elements including diet, obesity, disruption of lipid homeostasis, and a high buildup of triglycerides and other lipids in liver cells. It is therefore linked to an increase in the susceptibility to developing diabetes mellitus and cardiovascular diseases. Several interventions exist regarding its management, but the availability of natural sources through diet will be a benefit in dealing with the disorder due to the immensely growing dependence of the population worldwide on natural sources owing to their ability to treat the root cause of the disease. Anthocyanins (ACNs) are naturally occurring polyphenolic pigments that exist in the form of glycosides, which are the glucosides of anthocyanidins and are produced from flavonoids via the phenyl propanoid pathway. To understand their mode of action in NAFLD and their therapeutic potential, the literature on in vitro, in vivo, and clinical trials on naturally occurring ACN-rich sources was exhaustively reviewed. It was concluded that ACNs show their potential in the treatment of NAFLD through their antioxidant properties and their efficacy to control lipid metabolism, glucose homeostasis, transcription factors, and inflammation. This led to the conclusion that ACNs possess efficacy in the amelioration of NAFLD and the various features associated with it. However, additional clinical trials are required to justify the potential of ACNs in NAFLD.

Dietary nitrate intake and association with markers of cardiometabolic risk in Iranian female adolescents

Dietary nitrates are thought to confer several cardiometabolic health benefits, including improvements in blood pressure and the plasma lipid profile. However, existing data from Iran is conflicting and there is a dearth of literature focusing on non-adult populations. A total of 988 adolescent girls were recruited from schools in different areas of Mashhad and Sabzevar, Iran. Dietary nitrate intake was assessed using a food frequency questionnaire and participants were categorized into quartiles based on this. Differences in participant characteristics between quartiles were assessed using one-way ANOVA and associations between total nitrate intake, nitrate intake from vegetables and cardiometabolic risk markers (blood lipid profile, fasting blood glucose, systolic and diastolic blood pressure) were assessed using linear regression. Nitrate intake from vegetables was positively correlated with triglycerides, even after adjusting for several variables (β = 0.086, 95% CI = 0.002-0.097; P = 0.043). Total nitrate intake was also significantly positively associated with serum triglycerides (β = 0.097, 95% CI = 0.010-0.084; P = 0.012); however, this relationship disappeared after adjusting for several variables. Significant interaction effects were observed between total nitrate intake, nitrate intake from vegetables, and vitamin C upon triglycerides (P < 0.01). No significant relationships were found between total nitrate intake, nitrate intake from vegetables, and other cardiometabolic risk markers. Our findings suggest there may be neutral or possibly detrimental cardiovascular effects of dietary nitrate and/or vitamin C intake which are not in agreement with contemporary literature and warrant further investigation.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family in physiological and pathophysiological process and diseases

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family (PGC-1s), consisting of three members encompassing PGC-1α, PGC-1β, and PGC-1-related coactivator (PRC), was discovered more than a quarter-century ago. PGC-1s are essential coordinators of many vital cellular events, including mitochondrial functions, oxidative stress, endoplasmic reticulum homeostasis, and inflammation. Accumulating evidence has shown that PGC-1s are implicated in many diseases, such as cancers, cardiac diseases and cardiovascular diseases, neurological disorders, kidney diseases, motor system diseases, and metabolic disorders. Examining the upstream modulators and co-activated partners of PGC-1s and identifying critical biological events modulated by downstream effectors of PGC-1s contribute to the presentation of the elaborate network of PGC-1s. Furthermore, discussing the correlation between PGC-1s and diseases as well as summarizing the therapy targeting PGC-1s helps make individualized and precise intervention methods. In this review, we summarize basic knowledge regarding the PGC-1s family as well as the molecular regulatory network, discuss the physio-pathological roles of PGC-1s in human diseases, review the application of PGC-1s, including the diagnostic and prognostic value of PGC-1s and several therapies in pre-clinical studies, and suggest several directions for future investigations. This review presents the immense potential of targeting PGC-1s in the treatment of diseases and hopefully facilitates the promotion of PGC-1s as new therapeutic targets.

Functional overlap between the mammalian Sar1a and Sar1b paralogs in vivo

Proteins carrying a signal peptide and/or a transmembrane domain enter the intracellular secretory pathway at the endoplasmic reticulum (ER) and are transported to the Golgi apparatus via COPII vesicles or tubules. SAR1 initiates COPII coat assembly by recruiting other coat proteins to the ER membrane. Mammalian genomes encode two SAR1 paralogs, SAR1A and SAR1B. While these paralogs exhibit ~90% amino acid sequence identity, it is unknown whether they perform distinct or overlapping functions in vivo. We now report that genetic inactivation of Sar1a in mice results in lethality during mid-embryogenesis. We also confirm previous reports that complete deficiency of murine Sar1b results in perinatal lethality. In contrast, we demonstrate that deletion of Sar1b restricted to hepatocytes is compatible with survival, though resulting in hypocholesterolemia that can be rescued by adenovirus-mediated overexpression of either SAR1A or SAR1B. To further examine the in vivo function of these 2 paralogs, we genetically engineered mice with the Sar1a coding sequence replacing that of Sar1b at the endogenous Sar1b locus. Mice homozygous for this allele survive to adulthood and are phenotypically normal, demonstrating complete or near-complete overlap in function between the two SAR1 protein paralogs in mice. These data also suggest upregulation of SAR1A gene expression as a potential approach for the treatment of SAR1B deficiency (chylomicron retention disease) in humans.

The Effect and Mechanism of Oleanolic Acid in the Treatment of Metabolic Syndrome and Related Cardiovascular Diseases

Metabolic syndromes (MetS) and related cardiovascular diseases (CVDs) pose a serious threat to human health. MetS are metabolic disorders characterized by obesity, dyslipidemia, and hypertension, which increase the risk of CVDs' initiation and development. Although there are many availabile drugs for treating MetS and related CVDs, some side effects also occur. Considering the low-level side effects, many natural products have been tried to treat MetS and CVDs. A five-cyclic triterpenoid natural product, oleanolic acid (OA), has been reported to have many pharmacologic actions such as anti-hypertension, anti-hyperlipidemia, and liver protection. OA has specific advantages in the treatment of MetS and CVDs. OA achieves therapeutic effects through a variety of pathways, attracting great interest and playing a vital role in the treatment of MetS and CVDs. Consequently, in this article, we aim to review the pharmacological actions and potential mechanisms of OA in treating MetS and related CVDs.

The Intersection of Genetic Factors, Aberrant Nutrient Metabolism and Oxidative Stress in the Progression of Cardiometabolic Disease

Cardiometabolic disease (CMD), which encompasses metabolic-associated fatty liver disease (MAFLD), chronic kidney disease (CKD) and cardiovascular disease (CVD), has been increasing considerably in the past 50 years. CMD is a complex disease that can be influenced by genetics and environmental factors such as diet. With the increased reliance on processed foods containing saturated fats, fructose and cholesterol, a mechanistic understanding of how these molecules cause metabolic disease is required. A major pathway by which excessive nutrients contribute to CMD is through oxidative stress. In this review, we discuss how oxidative stress can drive CMD and the role of aberrant nutrient metabolism and genetic risk factors and how they potentially interact to promote progression of MAFLD, CVD and CKD. This review will focus on genetic mutations that are known to alter nutrient metabolism. We discuss the major genetic risk factors for MAFLD, which include Patatin-like phospholipase domain-containing protein 3 (PNPLA3), Membrane Bound O-Acyltransferase Domain Containing 7 (MBOAT7) and Transmembrane 6 Superfamily Member 2 (TM6SF2). In addition, mutations that prevent nutrient uptake cause hypercholesterolemia that contributes to CVD. We also discuss the mechanisms by which MAFLD, CKD and CVD are mutually associated with one another. In addition, some of the genetic risk factors which are associated with MAFLD and CVD are also associated with CKD, while some genetic risk factors seem to dissociate one disease from the other. Through a better understanding of the causative effect of genetic mutations in CMD and how aberrant nutrient metabolism intersects with our genetics, novel therapies and precision approaches can be developed for treating CMD.

Dietary oleic acid intake increases the proportion of type 1 and 2X muscle fibers in mice

Skeletal muscle is one of the largest metabolic tissues in mammals and is composed of four different types of muscle fibers (types 1, 2A, 2X, and 2B); however, type 2B is absent in humans. Given that slow-twitch fibers are superior to fast-twitch fibers in terms of oxidative metabolism and are rich in mitochondria, shift of muscle fiber types in direction towards slower fiber types improves metabolic disorders and endurance capacity. We previously had reported that oleic acid supplementation increases type 1 fiber formation in C2C12 myotubes; however, its function still remains unclear. This study aimed to determine the effect of oleic acid on the muscle fiber types and endurance capacity. An in vivo mouse model was used, and mice were fed a 10% oleic acid diet for 4 weeks. Two different skeletal muscles, slow soleus muscle with the predominance of slow-twitch fibers and fast extensor digitorum longus (EDL) muscle with the predominance of fast-twitch fibers, were used. We found that dietary oleic acid intake improved running endurance and altered fiber type composition of muscles, the proportion of type 1 and 2X fibers increased in the soleus muscle and type 2X increased in the EDL muscle. The fiber type shift in the EDL muscle was accompanied by an increased muscle TAG content. In addition, blood triacylglycerol (TAG) and non-esterified fatty acid levels decreased during exercise. These changes suggested that lipid utilization as an energy substrate was enhanced by oleic acid. Increased proliferator-activated receptor γ coactivator-1β protein levels were observed in the EDL muscle, which potentially enhanced the fiber type transitions towards type 2X and muscle TAG content. In conclusion, dietary oleic acid intake improved running endurance with the changes of muscle fiber type shares in mice. This study elucidated a novel functionality of oleic acid in skeletal muscle fiber types. Further studies are required to elucidate the underlying mechanisms. Our findings have the potential to contribute to the field of health and sports science through nutritional approaches, such as the development of supplements aimed at improving muscle function.

Polysaccharides from Brassica rapa root: Extraction, purification, structural features, and biological activities. A review

Brassica rapa (B. rapa) roots are attracting increased attention from nutritionists and health-conscious customers because of their remarkable performance in supplying necessary nutrients. Polysaccharides are major biologically active substances in B. rapa roots, which come in a variety of monosaccharides with different molar ratios and glycosidic bond types. Depending on the source, extraction, separation, and purification methods of B. rapa roots polysaccharides (BRP); different structural features, and pharmacological activities are elucidated. Polysaccharides from B. rapa roots possess a range of nutritional, biological, and health-enhancing characteristics, including anti-hypoxic, antifatigue, immunomodulatory, hypoglycemic, anti-tumor, and antioxidant activities. This paper reviewed extraction and purification methods, structural features, and biological activities as well as correlations between the structural and functional characteristics of polysaccharides from the B. rapa roots. Ultimately, this work will serve as useful reference for understanding the connections between polysaccharide structure and biological activity and developing novel BRP-based functional foods.

Circadian clock and lipid metabolism disorders: a potential therapeutic strategy for cancer

Recent research has emphasized the interaction between the circadian clock and lipid metabolism, particularly in relation to tumors. This review aims to explore how the circadian clock regulates lipid metabolism and its impact on carcinogenesis. Specifically, targeting key enzymes involved in fatty acid synthesis (SREBP, ACLY, ACC, FASN, and SCD) has been identified as a potential strategy for cancer therapy. By disrupting these enzymes, it may be possible to inhibit tumor growth by interfering with lipid metabolism. Transcription factors, like SREBP play a significant role in regulating fatty acid synthesis which is influenced by circadian clock genes such as BMAL1, REV-ERB and DEC. This suggests a strong connection between fatty acid synthesis and the circadian clock. Therefore, successful combination therapy should target fatty acid synthesis in addition to considering the timing and duration of drug use. Ultimately, personalized chronotherapy can enhance drug efficacy in cancer treatment and achieve treatment goals.

Associations between dietary intake and physical activity, as behavioral indicators, with body fat in adolescents from Mexico

Introduction

Introduction: the prevention of cardiometabolic diseases is currently a priority due to its relationship with COVID-19 complications. Unhealthy lifestyles, like inadequate diet and physical inactivity, are the cornerstone for obesity and cardiometabolic risk. Objective: to examine the association between diet and physical activity with body fat in Mexican adolescents. Methods: the study was cross-sectional. Data included socio-demographic variables, health history and smoking habit obtained through questionnaires; blood pressure and anthropometry measurements; food and nutrient intake through 24-hour recalls; and physical activities through the International Physical Activity Questionnaire (IPAQ). Univariate analyses were used and multiple models were built by stepwise forward selection (p ≤ 0.05 and biological plausibility). Results: participants were n = 230 students, 18.5 ± 0.4 years and 54.8 % men. Three models associated with body fat were obtained. In the first model, saturated fatty acids (β = 0.30, p = 0.028) were significant positive associated, while vigorous physical activity was significant negative associated as a protective factor (β = -0.007, p = 0.023). In the second model, total fat (β = 0.17, p = 0.005) was significant positive associated, and vigorous physical activity was significant negative associated (β = -0.007, p = 0.023). The third model included fruits and vegetables (β = -5.49, p = 0.092) and vigorous physical activity (β = -0.006, p = 0.058) as protective factors. Conclusions: dietary intake of total fat and saturated fatty acids, and vigorous physical activity, were significantly associated with body fat, while fruits and vegetables trended toward significance, in Mexican adolescents. Community-based programs that promote intake of protective foods and reduction of risky foods, and encourage vigorous physical activity, are needed in adolescents.

Effect of FTY720P on lipid accumulation in HEPG2 cells

Nonalcoholic fatty liver disease (NAFLD) is characterized by an increase in hepatic lipid accumulation due to impaired lipid metabolism. Although a correlation was found between NAFLD and sphingosine-1-phosphate (S1P), the role of the sphingolipid remains controversial. The aim of this study was to investigate any involvement of S1P in steatosis using its analog FTY720P and HepG2 cells. Lipid accumulation was induced by incubating the cells in a mixture of oleic and palmitic acid, and was quantified using Oil Red O. The involvement of signaling mediators was studied using pharmacological inhibitors and western blot analysis. FTY720P increased lipid accumulation, but this increase wasn't maintained in the presence of inhibitors of S1PR3, Gq, SREBP, mTOR, PI3K, and PPARγ indicating their involvement in the process. The results revealed that FTY720P binds to S1PR3 which activates sequentially Gq, PI3K, and mTOR leading to an increase in SREBP expression and PPARγ activation. It was concluded that in presence of a high level of fatty acids, lipid accumulation is increased in hepatocytes by the exogenously added FTY720P.

Effect of DHCR7 for the co-occurrence of hypercholesterolemia and vitamin D deficiency in type 2 diabetes: Perspective of health prevention

Type 2 diabetes mellitus (T2DM) is a complex disease caused by multiple factors, which are often accompanied by the disorder of glucose and lipid metabolism and the lack of vitamin D.Over the years, researchers have conducted numerous studies into the pathogenesis and prevention strategies of diabetes. In this study, diabetic SD rats were randomly divided into type 2 diabetes group, vitamin D intervention group, 7-dehydrocholesterole reductase (DHCR7) inhibitor intervention group, simvastatin intervention group, and naive control group. Before and 12 weeks after intervention, liver tissue was extracted to isolate hepatocytes. Compared with naive control group, in the type 2 diabetic group without interference, the expression of DHCR7 increased, the level of 25(OH)D3 decreased, the level of cholesterol increased. In the primary cultured naive and type 2 diabetic hepatocytes, the expression of genes related to lipid metabolism and vitamin D metabolism were differently regulated in each of the 5 treatment groups. Overall, DHCR7 is an indicator for type 2 diabetic glycolipid metabolism disorder and vitamin D deficiency. Targeting DHCR7 will help with T2DM therapy.The management model of comprehensive health intervention can timely discover the disease problems of diabetes patients and high-risk groups and reduce the incidence of diabetes.

Healthy regulation of Tibetan Brassica rapa L. polysaccharides on alleviating hyperlipidemia: A rodent study

Hyperlipidemia is a common metabolic disorder, which can lead to obesity, hypertension, diabetes, atherosclerosis and other diseases. Studies have shown that polysaccharides absorbed by the intestinal tract can regulate blood lipids and facilitate the growth of intestinal flora. This article aims to investigate whether Tibetan turnip polysaccharide (TTP) plays a protective role in blood lipid and intestinal health via hepatic and intestinal axes. Here we show that TTP helps to reduce the size of adipocytes and the accumulation of liver fat, playing a dose-dependent effect on ADPN levels, suggesting an effect on lipid metabolism regulation. Meantime, TTP intervention results in the downregulation of intercellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and serum inflammatory factors (interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α)), implying that TTP suppresses the progression of inflammation in the body. The expression of key enzymes associated with cholesterol and triglyceride synthesis, such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), cholesterol 7α-hydroxylase (CYP7A1), peroxisome proliferator-activated receptors γ (PPARγ), acetyl-CoA carboxylase (ACC), fatty acid synthetase (FAS) and sterol-regulatory element binding proteins-1c (SREBP-1c), can be modulated by TTP. Furthermore, TTP also alleviates the damage to intestinal tissues caused by high-fat diet, restores the integrity of the intestinal barrier, improves the composition and abundance of the intestinal flora and increases the levels of SCFAs. This study provides a theoretical basis for the regulation of body rhythm by functional foods and potential intervention in patients with hyperlipidemia.

How the Oviduct Lipidomic Profile Changes over Time after the Start of an Obesogenic Diet in an Outbred Mouse Model

We investigated whether a high-fat/high-sugar (HF/HS) diet alters the lipidomic profile of the oviductal epithelium (OE) and studied the patterns of these changes over time. Female outbred Swiss mice were fed either a control (10% fat) or HF/HS (60% fat, 20% fructose) diet. Mice (n = 3 per treatment per time point) were sacrificed and oviducts were collected at 3 days and 1, 4, 8, 12 and 16 weeks on the diet. Lipids in the OE were imaged using matrix-assisted laser desorption ionisation mass spectrometry imaging. Discriminative m/z values and differentially regulated lipids were determined in the HF/HS versus control OEs at each time point. Feeding the obesogenic diet resulted in acute changes in the lipid profile in the OE already after 3 days, and thus even before the development of an obese phenotype. The changes in the lipid profile of the OE progressively increased and became more persistent after long-term HF/HS diet feeding. Functional annotation revealed a differential abundance of phospholipids, sphingomyelins and lysophospholipids in particular. These alterations appear to be not only caused by the direct accumulation of the excess circulating dietary fat but also a reduction in the de novo synthesis of several lipid classes, due to oxidative stress and endoplasmic reticulum dysfunction. The described diet-induced lipidomic changes suggest alterations in the OE functions and the oviductal microenvironment which may impact crucial reproductive events that take place in the oviduct, such as fertilization and early embryo development.

Insulin Regulation of Hepatic Lipid Homeostasis

The incidence of obesity, insulin resistance, and type II diabetes (T2DM) continues to rise worldwide. The liver is a central insulin-responsive metabolic organ that governs whole-body metabolic homeostasis. Therefore, defining the mechanisms underlying insulin action in the liver is essential to our understanding of the pathogenesis of insulin resistance. During periods of fasting, the liver catabolizes fatty acids and stored glycogen to meet the metabolic demands of the body. In postprandial conditions, insulin signals to the liver to store excess nutrients into triglycerides, cholesterol, and glycogen. In insulin-resistant states, such as T2DM, hepatic insulin signaling continues to promote lipid synthesis but fails to suppress glucose production, leading to hypertriglyceridemia and hyperglycemia. Insulin resistance is associated with the development of metabolic disorders such as cardiovascular and kidney disease, atherosclerosis, stroke, and cancer. Of note, nonalcoholic fatty liver disease (NAFLD), a spectrum of diseases encompassing fatty liver, inflammation, fibrosis, and cirrhosis, is linked to abnormalities in insulin-mediated lipid metabolism. Therefore, understanding the role of insulin signaling under normal and pathologic states may provide insights into preventative and therapeutic opportunities for the treatment of metabolic diseases. Here, we provide a review of the field of hepatic insulin signaling and lipid regulation, including providing historical context, detailed molecular mechanisms, and address gaps in our understanding of hepatic lipid regulation and the derangements under insulin-resistant conditions. © 2023 American Physiological Society. Compr Physiol 13:4785-4809, 2023.

Myeloid-derived growth factor alleviates non-alcoholic fatty liver disease alleviates in a manner involving IKKβ/NF-κB signaling

Whether bone marrow modulates systemic metabolism remains unknown. Our recent study suggested that myeloid-derived growth factor (MYDGF) improves insulin resistance. Here, we found that myeloid cell-specific MYDGF deficiency aggravated hepatic inflammation, lipogenesis, and steatosis, and show that myeloid cell-derived MYDGF restoration alleviated hepatic inflammation, lipogenesis, and steatosis. Additionally, recombinant MYDGF attenuated inflammation, lipogenesis, and fat deposition in primary mouse hepatocytes (PMHs). Importantly, inhibitor kappa B kinase beta/nuclear factor-kappa B (IKKβ/NF-κB) signaling is involved in protection of MYDGF on non-alcoholic fatty liver disease (NAFLD). These data revealed that myeloid cell-derived MYDGF alleviates NAFLD and inflammation in a manner involving IKKβ/NF-κB signaling, and serves as a factor involved in the crosstalk between the liver and bone marrow that regulates liver fat metabolism. Bone marrow functions as an endocrine organ and serves as a potential therapeutic target for metabolic disorders.

α-Tocopherol-13'-Carboxychromanol Induces Cell Cycle Arrest and Cell Death by Inhibiting the SREBP1-SCD1 Axis and Causing Imbalance in Lipid Desaturation

α-Tocopherol-13'-carboxychromanol (α-T-13'-COOH) is an endogenously formed bioactive α-tocopherol metabolite that limits inflammation and has been proposed to exert lipid metabolism-regulatory, pro-apoptotic, and anti-tumoral properties at micromolar concentrations. The mechanisms underlying these cell stress-associated responses are, however, poorly understood. Here, we show that the induction of G₀/G₁ cell cycle arrest and apoptosis in macrophages triggered by α-T-13'-COOH is associated with the suppressed proteolytic activation of the lipid anabolic transcription factor sterol regulatory element-binding protein (SREBP)1 and with decreased cellular levels of stearoyl-CoA desaturase (SCD)1. In turn, the fatty acid composition of neutral lipids and phospholipids shifts from monounsaturated to saturated fatty acids, and the concentration of the stress-preventive, pro-survival lipokine 1,2-dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol) [PI(18:1/18:1)] decreases. The selective inhibition of SCD1 mimics the pro-apoptotic and anti-proliferative activity of α-T-13'-COOH, and the provision of the SCD1 product oleic acid (C18:1) prevents α-T-13'-COOH-induced apoptosis. We conclude that micromolar concentrations of α-T-13'-COOH trigger cell death and likely also cell cycle arrest by suppressing the SREBP1-SCD1 axis and depleting cells of monounsaturated fatty acids and PI(18:1/18:1).

Dietary tea seed saponin combined with aerobic exercise attenuated lipid metabolism and oxidative stress in mice fed a high-fat diet (HFD)

Tea seed saponins (TSS) are oleanolane-type pentacyclic triterpenoid saponin mixtures with various pharmacological effects. We aimed to explore the effects of a total of 4 weeks intragastric administration of TSS (140 mg/kg·day) combined with aerobic exercise (AE) on lipid metabolism and its associated oxidative stress in HFD-induced obese mice and to investigate the possible molecular mechanisms. TSS + AE intervention significantly reduced body weight and the adiposity index (including subcutaneous, epididymal, perirenal, and abdominal adipose) in obese mice; improved dyslipidemia by lowering serum TC, TG, and LDL-c levels; and increased HDL-c levels. TSS + AE intervention significantly improved hepatic steatosis by inhibiting lipogenetic Acc, Srebp1c, and Scd1 and upregulating lipolysis genes (Pgc1α, Pgc1β, Pparα, and Cpt1). TSS + AE intervention increased the hepatic protein expression of p-AMPK, SIRT1, and PGC-1α, as well as PPAR-γ and GLUT-4 in skeletal muscle compared with expression in the HFD group. In addition, TSS + AE also modulated oxidative stress in obese mice, which was indicated by the increased serum and liver levels of SOD, GSH, and T-AOC and decreased ROS and MDA levels. These results suggest that TSS + AE intervention can reduce fat accumulation and improve HFD-induced lipid metabolism disorders and oxidative stress. PRACTICAL APPLICATIONS: Obesity is a metabolic disease induced by excess nutritional intake and insufficient energy expenditure. Dietary modifications combined with aerobic exercise are currently an effective method for weight loss. Tea seed saponins (TSS) are a variety of biologically active oleanolane-type pentacyclic triterpenoid saponins that naturally exist in tea seeds. Few articles have focused on the effects and mechanisms of TSS combined with aerobic exercise (AE) in regulating lipid metabolism and improving oxidative damage in vivo. Using an HFD-induced obese mice model to explore the mechanism of TSS + AE in regulating lipid metabolism and its associated oxidative stress damage will help provide reliable data for the application of dietary nutrition combined with AE in anti-obesity.

Di-(2-ethylhexyl) phthalate increases plasma glucose and induces lipid metabolic disorders via FoxO1 in adult mice

Di-(2-ethylhexyl) phthalate (DEHP), an endocrine-disrupting chemical (EDC) commonly used as a plasticizer, is responsible for widespread environmental pollution. Epidemiological and experimental data implicate DEHP and its metabolite mono(2-ethylhexyl) phthalate (MEHP) in the occurrence and development of metabolic syndrome. However, the specific effects and potential mechanisms of action of DEHP on glucose and lipid metabolism in adults are currently unclear. In the current study, adult male mice were continuously exposed to DEHP (0, 5, and 25 mg/kg/day) via oral administration and changes in glucose and lipid metabolism explored. Notably, exposure to DEHP led to a significant increase in plasma glucose and hepatic lipid accumulation but had no effect on insulin secretion. Western blot and real-time quantitative PCR showed that DEHP induced insulin resistance and promoted gluconeogenesis and lipid accumulation via overexpression of forkhead box protein O1 (FoxO1), in keeping with hepatic RNA sequencing data. Variations in gut microbiota aggravated these effects while inhibition of FoxO1 reversed the adverse effects of DEHP. Our findings support a key role of FoxO1 in disorders of glucose and lipid metabolism caused by DEHP.

Effects of an obesogenic diet on the oviduct depend on the duration of feeding

Research question

How long does it take for an obesogenic (high-fat/high-sugar, HF/HS) diet to influence the oviductal microenvironment? What are the affected cellular pathways and are they dependent on the genetic background of the mouse model?

Design

Female Swiss (outbred) and C57BL/6N (B6, inbred) mice were fed either a control (10% fat) or HF/HS (60% fat, 20% fructose) diet. Body weight was measured weekly. Mice were sacrificed at 3 days (3d), 1 week (1w), 4w, 8w, 12w and 16w on the diet (n = 5 per treatment per time point). Total cholesterol concentrations and inflammatory cytokines were measured in serum. Oviductal epithelial cells (OECs) were used to study the expression of genes involved in (mitochondrial) oxidative stress (OS), endoplasmic reticulum (ER) stress and inflammation using qPCR.

Results

Body weight and blood cholesterol increased significantly in the HF/HS mice in both strains compared to controls. In Swiss mice, HF/HS diet acutely increased ER-stress and OS-related genes in the OECs already after 3d. Subsequently, mitochondrial and cytoplasmic antioxidants were upregulated and ER-stress was alleviated at 1w. After 4-8w (mid-phase), the expression of ER-stress and OS-related genes was increased again and persisted throughout the late-phase (12-16w). Serum inflammatory cytokines and inflammatory marker-gene expression in the OECs were increased only in the late-phase. Some of the OEC stress responses were stronger or earlier in the B6.

Conclusions

OECs are sensitive to an obesogenic diet and may exhibit acute stress responses already after a few days of feeding. This may impact the oviductal microenvironment and contribute to diet-induced subfertility.

PGC-1β maintains mitochondrial metabolism and restrains inflammatory gene expression

Metabolic programming of the innate immune cells known as dendritic cells (DCs) changes in response to different stimuli, influencing their function. While the mechanisms behind increased glycolytic metabolism in response to inflammatory stimuli are well-studied, less is known about the programming of mitochondrial metabolism in DCs. We used lipopolysaccharide (LPS) and interferon-β (IFN-β), which differentially stimulate the use of glycolysis and oxidative phosphorylation (OXPHOS), respectively, to identify factors important for mitochondrial metabolism. We found that the expression of peroxisome proliferator-activated receptor gamma co-activator 1β (PGC-1β), a transcriptional co-activator and known regulator of mitochondrial metabolism, decreases when DCs are activated with LPS, when OXPHOS is diminished, but not with IFN-β, when OXPHOS is maintained. We examined the role of PGC-1β in bioenergetic metabolism of DCs and found that PGC-1β deficiency indeed impairs their mitochondrial respiration. PGC-1β-deficient DCs are more glycolytic compared to controls, likely to compensate for reduced OXPHOS. PGC-1β deficiency also causes decreased capacity for ATP production at steady state and in response to IFN-β treatment. Loss of PGC-1β in DCs leads to increased expression of genes in inflammatory pathways, and reduced expression of genes encoding proteins important for mitochondrial metabolism and function. Collectively, these results demonstrate that PGC-1β is a key regulator of mitochondrial metabolism and negative regulator of inflammatory gene expression in DCs.

Nutrient-Mediated Perception and Signalling in Human Metabolism: A Perspective of Nutrigenomics

The interaction between selective nutrients and linked genes involving a specific organ reveals the genetic make-up of an individual in response to a particular nutrient. The interaction of genes with food opens opportunities for the addition of bioactive compounds for specific populations comprising identical genotypes. The slight difference in the genetic blueprints of humans is advantageous in determining the effect of nutrients and their metabolism in the body. The basic knowledge of emerging nutrigenomics and nutrigenetics can be applied to optimize health, prevention, and treatment of diseases. In addition, nutrient-mediated pathways detecting the cellular concentration of nutrients such as sugars, amino acids, lipids, and metabolites are integrated and coordinated at the organismal level via hormone signals. This review deals with the interaction of nutrients with various aspects of nutrigenetics and nutrigenomics along with pathways involved in nutrient sensing and regulation, which can provide a detailed understanding of this new leading edge in nutrition research and its potential application to dietetic practice.

Regulation of lipid droplet (LD) formation in hepatocytes via regulation of SREBP1c by non-coding RNAs

Introduction

Increased de novo lipogenesis (DNL) is one of the key factors contributing to fat accumulation and non-alcoholic fatty liver disease (NAFLD). Among the critical transcription factors (TFs) regulating DNL is mTOR and its downstream lipogenic TF, SREBP1c. In recent years, it has been established that non-coding RNAs (ncRNAs) play role in both biological processes and disease pathogenesis. Our group has previously characterized microRNAs that can target and regulate the expression of both mTOR and SREBP1c. Accordingly, this study aimed to broaden our understanding of the role of ncRNAs in regulating the mTOR/SREBP1c axis to elucidate the role of the non-coding transcriptome in DNL and lipid droplet (LD) formation. Hence, short ncRNA, miR-615-5p, and long non-coding RNA (lncRNA), H19, were chosen as they were previously proven to target mTOR by our group and in the published literature, respectively.

Methodology

Huh-7 cells were treated with 800 μM oleic acid (OA) to promote LD formation. Transfection of miR-615-5p mimics or H19 over-expression vectors was performed, followed by the measurement of their downstream targets, mTOR and SREBP, on the mRNA level by quantitative real-time PCR (qRT-PCR), and on the protein level by Western blot. To determine the functional impact of miR-615-5p and H19 on LD formation and triglyceride (TG) accumulation, post-transfection LDs were stained, imaged, and characterized, and TGs were extracted and quantified.

Results

miR-615-5p was able to reduce mTOR and SREBP1c significantly on both the mRNA and protein levels compared to control cells, while H19 caused a reduction of both targets on the protein level only. Both miR-615-5p and H19 were able to significantly reduce the LD count and total area, as well as TG levels compared to control cells.

Conclusion

To conclude, this study shows, for the first time, the impact of miR-615-5p and H19 on the mTOR/SREBP1c axis, and thus, their functional impact on LDs and TG accumulation. These findings might pave the way for using ncRNAs as potential therapeutic targets in the management of fatty liver.

Lipid metabolism and retinal diseases

PURPOSE

The retina has enormous lipids demands and must meet those needs. Retinal lipid homeostasis appears to be based on the symbiosis between neurons, Müller glial cells (MGC), and retinal pigment epithelium (RPE) cells, which can be impacted in several retinal diseases. The current research challenge is to better understand lipid-related mechanisms involved in retinal diseases, such as age-related macular degeneration (AMD) and glaucoma.

RESULTS

In a first axis, in vitro and focus on Müller glial cell, we aimed to characterize whether the 24S-hydroxycholesterol (24S-OHC), an overexpressed end-product of cholesterol elimination pathway in neural tissue and likely produced by suffering retinal ganglion cells in glaucoma, may modulate MGC membrane organization, such as lipid rafts, to trigger cellular signalling pathways related to retinal gliosis. We have found that lipid composition appears to be a key factor of membrane architecture, especially for lipid raft microdomain formation, in MGC. However, 24S-OHC did not appear to trigger retinal gliosis via the modulation of lipid or protein composition within lipid rafts microdomains. This study provided a better understanding of the complex mechanisms involved in the pathophysiology of glaucoma. On a second clinical ax, we focused on the lipid-related mechanisms involved in the dysfunction of aging RPE and the appearance of drusenoid deposits in AMD. Using the Montrachet population-based study, we intend to report the frequency of reticular pseudodrusen (RPD) and its ocular and systemic risk factors, particularly related to lipid metabolisms, such as plasma lipoprotein levels, carotenoids levels, and lipid-lowering drug intake. Our study showed that RPD was less common in subjects taking lipid-lowering drugs. Lipid-lowering drugs, such as statins, may reduce the risk of RPD through their effect on the production and function of lipoproteins. This observation highlights the potential role of retinal lipid trafficking via lipoproteins between photoreceptors and retinal pigment epithelium cells in RPD formation. Those findings have been complemented with preliminary results on the analysis of plasma fatty acid (FA) profile, a surrogate marker of short-term dietary lipid intake, according to the type of predominant drusenoid deposit, soft drusen or RPD, in age-related maculopathy.

CONCLUSION

Further research on lipid metabolism in retinal diseases is warranted to better understand the pathophysiology of retinal diseases and develop new promising diagnostic, prognostic, and therapeutic tools for our patients.

Molecular effects of the consumption of margarine and butter varying in trans fat composition: a parallel human intervention study

BACKGROUND

Whereas the dietary intake of industrial trans fatty acids (iTFA) has been specifically associated with inflammation, cardiovascular disease, and type 2 diabetes, understanding the impact of dietary fats on human health remains challenging owing to their complex composition and individual effects of their lipid components on metabolism. The aim of this study is to profile the composition of blood, measured by the fatty acid (FAs) profile and untargeted metabolome of serum and the transcriptome of blood cells, in order to identify molecular signatures that discriminate dietary fat intakes.

METHODS

In a parallel study, the molecular effects of consuming dairy fat containing ruminant TFA (rTFA) or margarine containing iTFA were investigated. Healthy volunteers (n = 42; 45-69 y) were randomly assigned to diets containing margarine without TFA as major source of fat (wTFA control group with 0.4 g TFA per 100 g margarine), margarine with iTFA (iTFA group with 4.1 g TFA per 100 g margarine), or butter with rTFA (rTFA group with 6.3 g TFA per 100 g butter) for 4 weeks. The amounts of test products were individually selected so that fat intake contributed to 30-33% of energy requirements and TFA in the rTFA and iTFA groups contributed to up to 2% of energy intake. Changes in fasting blood values of lipid profiles (GC with flame-ionization detection), metabolome profiles (LC-MS, GC-MS), and gene expression (microarray) were measured.

RESULTS

Eighteen FAs, as well as 242 additional features measured by LC-MS (185) and GC-MS (54) showed significantly different responses to the diets (PFDR-adjusted < 0.05), mainly distinguishing butter from the margarine diets while gene expression was not differentially affected. The most abundant TFA in the butter, i.e. TFA containing (E)-octadec-11-enoic acid (C18:1 t11; trans vaccenic acid), and margarines, i.e. TFA containing (E)-octadec-9-enoic acid (C18:1 t9; elaidic acid) were reflected in the significantly different serum levels of TFAs measured after the dietary interventions.

CONCLUSIONS

The untargeted serum metabolome differentiates margarine from butter intake although the identification of the discriminating features remains a bottleneck. The targeted serum FA profile provides detailed information on specific molecules differentiating not only butter from margarine intake but also diets with different content of iTFAs in margarine.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00933322.

Profound Elevation in LDL Cholesterol Level Following a Ketogenic Diet: A Case Series

The ketogenic diet (KD) is currently popular for the achievement of weight loss and improvement in glycemic variables. The diet allows consumption of foods high in fat and protein, with strict limitation of carbohydrates. We present a case series of substantial increases in total cholesterol and low-density lipoprotein cholesterol following the initiation of a KD, with improvements in cholesterol levels once the KD was stopped. Novel teaching points include the need for lipid monitoring in patients who choose to follow a KD and for raising awareness of the extreme lipid response that can occur in some patients, particularly lean individuals.

Gestational heat stress alters skeletal muscle gene expression profiles and vascularity in fetal pigs in a sexually dimorphic manner

BACKGROUND

There is evidence that sow heat stress (HS) during gestation affects fetal development with implications for impaired muscle growth. We have previously demonstrated that maternal HS during early to mid-gestation compromised muscle fibre hyperplasia in developing fetal pigs. Thus, we hypothesised these phenotypic changes are associated with a change in expression of genes regulating fetal skeletal muscle development and metabolism. To test this, at d 60 of gestation, RNA sequencing and immunohistochemistry were performed on fetal longissimus dorsi (LD) muscle biopsies collected from pregnant gilts that had experienced either thermoneutral control (CON, 20 °C, n = 7 gilts, 18 LD samples) or controlled HS (cyclic 28 to 33 °C, n = 8 gilts, 23 LD samples) conditions for 3 weeks.

RESULTS

A total of 282 genes were differentially expressed between the HS and CON groups in female LD muscles (false discovery rate (FDR) ≤ 0.05), whereas no differentially expressed genes were detected in male LD muscles between the two groups (FDR > 0.05). Gestational HS increased the expression of genes associated with transcription corepressor activity, adipogenesis cascades, negative regulation of angiogenesis and pro-inflammatory signalling in female LD muscles. Immunohistochemical analyses revealed a decreased muscle vascularity density in fetuses from HS group for both sexes compared to those from the CON group (P = 0.004).

CONCLUSIONS

These results reveal gilt HS during early to mid-gestation altered gene expression profiles in fetal LD muscles in a sexually dimorphic manner. The molecular responses, including transcription and angiogenesis repressions and enhanced adipogenesis cascades, were exclusively observed in females. However, the associated reductions in muscle vascularity were observed independently of sexes. Collectively this may indicate female fetal pigs are more adaptive to gestational HS in terms of gene expression changes, and/or there may be sexually dimorphic differences with respect to the timing of muscle molecular responses to gestational HS.

The Role of MicroRNAs in Hyperlipidemia: From Pathogenesis to Therapeutical Application

Hyperlipidemia is a common metabolic disorder with high morbidity and mortality, which brings heavy burden on social. Understanding its pathogenesis and finding its potential therapeutic targets are the focus of current research in this field. In recent years, an increasing number of studies have proved that miRNAs play vital roles in regulating lipid metabolism and were considered as promising therapeutic targets for hyperlipidemia and related diseases. It is demonstrated that miR-191, miR-222, miR-224, miR-27a, miR-378a-3p, miR-140-5p, miR-483, and miR-520d-5p were closely associated with the pathogenesis of hyperlipidemia. In this review, we provide brief overviews about advances in miRNAs in hyperlipidemia and its potential clinical application value.

Tissue-Specific Expression of Circ_015343 and Its Inhibitory Effect on Mammary Epithelial Cells in Sheep

Circular RNAs (circRNAs) are a kind of non-coding RNA that have an important molecular function in mammary gland development and lactation of mammals. In our previous study, circ_015343 was found to be highly expressed in the ovine mammary gland tissue at the peak-lactation period by using RNA sequencing (RNA-seq). In the present study, the authenticity of circ_015343 was confirmed by using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis and Sanger sequencing. The circ_015343 was derived from the complete 10 exons of aminoadipic semialdehyde synthase (AASS), ranging from exon 2 to exon 11 and mainly located in cytoplasm of ovine mammary epithelial cells. The circRNA was found to be expressed in eight ovine tissues, with the highest expression level in the mammary gland and the least expression in Longissimus dorsi muscle. The circ_015343 had a lower level of expression in a sheep breed with higher milk yield and milk fat content. The disturbed circ_015343 increased the viability and proliferation of the ovine mammary epithelial cells. The inhibition of circ_015343 also increased the expression levels of three milk fat synthesis marker genes: acetyl-coenzyme A carboxylase alpha (ACACA), fatty acid-binding protein 4 (FABP4), and sterol regulatory element-binding protein 1 (SREBP1), as well as three proliferation-related genes: cyclin dependent kinase 2 (CDK2), cyclin dependent kinase 4 (CDK4) and proliferating cell nuclear antigen (PCNA), but decreased the expression level of its parent gene AASS. A circRNA-miRNA-mRNA interaction network showed that circ_015343 would bind some microRNAs (miRNAs) to regulate the expression of functional genes related to the development of mammary gland and lactation. This study contributes to a better understanding of the roles of circ_015343 in the mammary gland of sheep.

Dyrk1b promotes hepatic lipogenesis by bypassing canonical insulin signaling and directly activating mTORC2 in mice

Mutations in Dyrk1b are associated with metabolic syndrome and nonalcoholic fatty liver disease in humans. Our investigations showed that DYRK1B levels are increased in the liver of patients with nonalcoholic steatohepatitis (NASH) and in mice fed with a high-fat, high-sucrose diet. Increasing Dyrk1b levels in the mouse liver enhanced de novo lipogenesis (DNL), fatty acid uptake, and triacylglycerol secretion and caused NASH and hyperlipidemia. Conversely, knockdown of Dyrk1b was protective against high-calorie-induced hepatic steatosis and fibrosis and hyperlipidemia. Mechanistically, Dyrk1b increased DNL by activating mTORC2 in a kinase-independent fashion. Accordingly, the Dyrk1b-induced NASH was fully rescued when mTORC2 was genetically disrupted. The elevated DNL was associated with increased plasma membrane sn-1,2-diacylglyerol levels and increased PKCε-mediated IRKT1150 phosphorylation, which resulted in impaired activation of hepatic insulin signaling and reduced hepatic glycogen storage. These findings provide insights into the mechanisms that underlie Dyrk1b-induced hepatic lipogenesis and hepatic insulin resistance and identify Dyrk1b as a therapeutic target for NASH and insulin resistance in the liver.

A propolis-derived small molecule ameliorates metabolic syndrome in obese mice by targeting the CREB/CRTC2 transcriptional complex

The molecular targets and mechanisms of propolis ameliorating metabolic syndrome are not fully understood. Here, we report that Brazilian green propolis reduces fasting blood glucose levels in obese mice by disrupting the formation of CREB/CRTC2 transcriptional complex, a key regulator of hepatic gluconeogenesis. Using a mammalian two-hybrid system based on CREB-CRTC2, we identify artepillin C (APC) from propolis as an inhibitor of CREB-CRTC2 interaction. Without apparent toxicity, APC protects mice from high fat diet-induced obesity, decreases fasting glucose levels, enhances insulin sensitivity and reduces lipid levels in the serum and liver by suppressing CREB/CRTC2-mediated both gluconeogenic and SREBP transcriptions. To develop more potential drugs from APC, we designed and found a novel compound, A57 that exhibits higher inhibitory activity on CREB-CRTC2 association and better capability of improving insulin sensitivity in obese animals, as compared with APC. In this work, our results indicate that CREB/CRTC2 is a suitable target for developing anti-metabolic syndrome drugs.

Recovery of Bacteroides thetaiotaomicron ameliorates hepatic steatosis in experimental alcohol-related liver disease

Alcohol-related liver disease (ALD) is a major cause of liver disease and represents a global burden, as treatment options are scarce. Whereas 90% of ethanol abusers develop alcoholic fatty liver disease (AFLD), only a minority evolves to steatohepatitis and cirrhosis. Alcohol increases lipogenesis and suppresses lipid-oxidation implying steatosis, although the key role of intestinal barrier integrity and microbiota in ALD has recently emerged. Bacteroides thetaiotaomicron (Bt) is a prominent member of human and murine intestinal microbiota, and plays important functions in metabolism, gut immunity, and mucosal barrier. We aimed to investigate the role of Bt in the genesis of ethanol-induced liver steatosis. Bt DNA was measured in feces of wild-type mice receiving a Lieber-DeCarli diet supplemented with an increase in alcohol concentration. In a second step, ethanol-fed mice were orally treated with living Bt, followed by analysis of intestinal homeostasis and histological and biochemical alterations in the liver. Alcohol feeding reduced Bt abundance, which was preserved by Bt oral supplementation. Bt-treated mice displayed lower hepatic steatosis and triglyceride content. Bt restored mucosal barrier and reduced LPS translocation by enhancing mucus thickness and production of Mucin2. Furthermore, Bt up-regulated Glucagon-like peptide-1 (GLP-1) expression and restored ethanol-induced Fibroblast growth factor 15 (FGF15) down-regulation. Lipid metabolism was consequently affected as Bt administration reduced fatty acid synthesis (FA) and improved FA oxidation and lipid exportation. Moreover, treatment with Bt preserved the mitochondrial fitness and redox state in alcohol-fed mice. In conclusion, recovery of ethanol-induced Bt depletion by oral supplementation was associated with restored intestinal homeostasis and ameliorated experimental ALD. Bt could serve as a novel probiotic to treat ALD in the future.

CD36 promotes de novo lipogenesis in hepatocytes through INSIG2-dependent SREBP1 processing

Objective

Enhanced de novo lipogenesis (DNL) in hepatocytes is a major contributor to nonalcoholic fatty liver disease (NAFLD). Fatty acid translocase (FAT/CD36) is involved in the pathogenesis of NAFLD through facilitating free fatty acids uptake. Here, we explored the effects of CD36 on DNL and elucidated the underlying mechanisms.

Methods

We generated hepatocyte-specific CD36 knockout (CD36LKO) mice to study in vivo effects of CD36 on DNL under high-fat diet (HFD). Lipid deposition and DNL were analyzed in primary hepatocytes isolated from CD36LKO mice or HepG2 cells with CD36 overexpression. RNA sequence, co-immunoprecipitation, and proximity ligation assay were carried out to determine its role in regulating DNL.

Results

Hepatic CD36 expression was upregulated in NAFLD mice and patients, and CD36LKO mice exhibited attenuated HFD-induced hepatic steatosis and insulin resistance. We identified hepatocyte CD36 as a key regulator for DNL in the liver. Sterol regulatory element-binding protein 1 (SREBP1) and its downstream lipogenic enzymes such as FASN, ACCα, and ACLY were significantly downregulated in the liver of HFD-fed CD36LKO mice, whereas overexpression CD36 stimulated insulin-mediated DNL and lipid droplet formation in vitro. Mechanistically, CD36 was activated by insulin and formed a complex with insulin-induced gene-2 (INSIG2) that disrupts the interaction between SREBP cleavage-activating protein (SCAP) and INSIG2, thereby leading to the translocation of SREBP1 from ER to Golgi for processing. Furthermore, treatment with 25-hydroxycholesterol or betulin molecules shown to enhance SCAP–INSIG interaction, reversed the effects of CD36 on SREBP1 cleavage.

Conclusions

Our findings identify a previously unsuspected role of CD36 in the regulation of hepatic lipogenic program through mediating SREBP1 processing by INSIG2, providing additional evidence for targeting CD36 in NAFLD.

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CD36 plays a novel role in DNL of hepatocytes beyond its known FFA transport function.

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CD36 regulates DNL via SREBP1 processing through interaction with INSIG2.

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Hepatocyte-specific intervention of CD36 is a hopeful therapeutic strategy for NAFLD.

Influence of Diet and Levels of Zonulin, Lipopolysaccharide and C-Reactive Protein on Cardiometabolic Risk Factors in Young Subjects

A western diet and increased intestinal permeability may contribute to systemic inflammation and the development of cardio-metabolic alterations. The aim of this study was to assess the relationship between diet, biomarkers of intestinal permeability, and chronic low-grade inflammation on the cardiometabolic profile. A cross-sectional study was carried out in 238 young subjects aged 18–29 years, divided into two groups: with <3 cardiometabolic risk factors (CRF) and ≥3 risk factors. Anthropometric parameters, biochemical profile, and serum levels of zonulin, lipopolysaccharide (LPS), and high-sensitivity C-reactive protein (hs-CRP) were measured, and the macronutrient intake was evaluated. Interaction models showed elevated glucose levels in the presence of high biomarker levels: zonulin ≥51.6 ng/mL plus LPS ≥ 1.35 EU/mL (β = 1.1, p = 0.006), and LPS ≥1.35 EU/mL plus hs-CRP ≥ 4.3 mg/L (β = 1.2, p = 0.007). In addition, triglyceride levels increased in the presence of LPS ≥ 1.35 EU/mL and hs-CRP ≥ 4.3 mg/L (β = 3.9, p = 0.01). Despite having increased biomarker levels, a higher consumption of water (≥2100 mL), polyunsaturated fatty acids (≥6.0 g), or fiber (≥30 g) decreased triglyceride (β = −9.6, p = 0.03), total cholesterol (β = −5.1, p = 0.01), and LDL-C levels (β = −7.7, p = 0.01). These findings suggest that the increased consumption of water, PUFA and fiber may improve lipid profile in subjects with intestinal permeability dysfunction or low-grade systemic inflammation.

Molecular aspects of fructose metabolism and metabolic disease

Excessive sugar consumption is increasingly considered as a contributor to the emerging epidemics of obesity and the associated cardiometabolic disease. Sugar is added to the diet in the form of sucrose or high-fructose corn syrup, both of which comprise nearly equal amounts of glucose and fructose. The unique aspects of fructose metabolism and properties of fructose-derived metabolites allow for fructose to serve as a physiological signal of normal dietary sugar consumption. However, when fructose is consumed in excess, these unique properties may contribute to the pathogenesis of cardiometabolic disease. Here, we review the biochemistry, genetics, and physiology of fructose metabolism and consider mechanisms by which excessive fructose consumption may contribute to metabolic disease. Lastly, we consider new therapeutic options for the treatment of metabolic disease based upon this knowledge.

Roles of IκB kinases and TANK-binding kinase 1 in hepatic lipid metabolism and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and is strongly associated with obesity-related ectopic fat accumulation in the liver. Hepatic lipid accumulation encompasses a histological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma. Given that dysregulated hepatic lipid metabolism may be an onset factor in NAFLD, understanding how hepatic lipid metabolism is modulated in healthy subjects and which steps are dysregulated in NAFLD subjects is crucial to identify effective therapeutic targets. Additionally, hepatic inflammation is involved in chronic hepatocyte damage during NAFLD progression. As a key immune signaling hub that mediates NF-κB activation, the IκB kinase (IKK) complex, including IKKα, IKKβ, and IKKγ (NEMO), has been studied as a crucial regulator of the hepatic inflammatory response and hepatocyte survival. Notably, TANK-binding kinase 1 (TBK1), an IKK-related kinase, has recently been revealed as a potential link between hepatic inflammation and energy metabolism. Here, we review (1) the biochemical steps of hepatic lipid metabolism; (2) dysregulated lipid metabolism in obesity and NAFLD; and (3) the roles of IKKs and TBK1 in obesity and NAFLD.