Molecular mechanisms regulating hormone-sensitive lipase and lipolysis

Function and therapeutic potential of Amuc_1100, an outer membrane protein of Akkermansia muciniphila: A review

The gut microbiota-derived protein Amuc_1100, a key outer membrane component of Akkermansia muciniphila, has emerged as a groundbreaking therapeutic agent with unique structural and functional properties. Amuc_1100 exerts multifaceted immune-metabolic effects through novel mechanisms, including modulation of TLR2/4 and JAK/STAT pathways. This review highlights its unique multi-component structure that enables synergistic biological activity, and its pharmacological properties, which underlies its ability to enhance intestinal barrier integrity, restore microbiota balance, and suppress systemic inflammation. Crucially, Amuc_1100 demonstrates unprecedented therapeutic versatility across both intestinal disorders (e.g., inflammatory bowel disease, antibiotic-associated diarrhea) and extraintestinal conditions-notably improving neuropsychiatric symptoms via gut-serotonin axis regulation, combating cancer through CD8+ T cell activation, and mitigating cardiotoxicity via gut-heart immune crosstalk. Emerging innovations in targeted delivery systems, including gut-retentive nano-formulations and engineered probiotic vectors, further amplify its clinical potential. We critically evaluate recent advances distinguishing Amuc_1100's mechanisms from live bacterial interventions. By synthesizing evidence from preclinical models, this work positions Amuc_1100 as a prototype for next-generation microbiome-derived therapeutics, bridging microbial ecology with precision medicine.

Effect of Cordyceps militaris extract containing cordycepin on the adipogenesis and lipolysis of adipocytes

Obesity, a global health concern, results from an energy imbalance leading to lipid accumulation. In the present study, Cordyceps militaris extract (CM) and its primary component, cordycepin, were investigated to characterize their potential effects on adipogenesis and lipolysis. Treatment with CM or cordycepin reduced lipid droplets and increased hormone-sensitive lipase activation in 3T3-L1 cells. In a diabetic obese mouse model, CM and cordycepin lowered serum low-density lipoprotein/very low-density lipoprotein levels and reduced oxidative stress and cell senescence markers. Thus, cordycepin inhibits preadipocyte differentiation and promotes lipolysis, which may serve as a novel obesity treatment. Further studies, including clinical trials, are required to validate the clinical potential of cordycepin.

Adipose Tissues Have Been Overlooked as Players in Prostate Cancer Progression

Obesity is a common risk factor in multiple tumor types, including prostate cancer. Obesity has been associated with driving metastasis, therapeutic resistance, and increased mortality. The effect of adipose tissue on the tumor microenvironment is still poorly understood. This review aims to highlight the work conducted in the field of obesity and prostate cancer and bring attention to areas where more research is needed. In this review, we have described key differences between healthy adipose tissues and obese adipose tissues, as they relate to the tumor microenvironment, focusing on mechanisms related to metabolic changes, abnormal adipokine secretion, altered immune cell presence, and heightened oxidative stress as drivers of prostate cancer formation and progression. Interestingly, common treatment options for prostate cancer ignore the adipose tissue located near the site of the tumor. Because of this, we have outlined how excess adipose tissue potentially affects therapeutics' efficacy, such as androgen deprivation, chemotherapy, and radiation treatment, and identified possible drug targets to increase prostate cancer responsiveness to clinical treatments. Understanding how obesity affects the tumor microenvironment will pave the way for understanding why some prostate cancers become metastatic or treatment-resistant, and why patients experience recurrence.

Deciphering adipose development: Function, differentiation and regulation

The overdevelopment of adipose tissues, accompanied by excess lipid accumulation and energy storage, leads to adipose deposition and obesity. With the increasing incidence of obesity in recent years, obesity is becoming a major risk factor for human health, causing various relevant diseases (including hypertension, diabetes, osteoarthritis and cancers). Therefore, it is of significance to antagonize obesity to reduce the risk of obesity-related diseases. Excess lipid accumulation in adipose tissues is mediated by adipocyte hypertrophy (expansion of pre-existing adipocytes) or hyperplasia (increase of newly-formed adipocytes). It is necessary to prevent excessive accumulation of adipose tissues by controlling adipose development. Adipogenesis is exquisitely regulated by many factors in vivo and in vitro, including hormones, cytokines, gender and dietary components. The present review has concluded a comprehensive understanding of adipose development including its origin, classification, distribution, function, differentiation and molecular mechanisms underlying adipogenesis, which may provide potential therapeutic strategies for harnessing obesity without impairing adipose tissue function.

Decoding the connection between lncRNA and obesity: Perspective from humans and Drosophila

Background

Obesity is a burgeoning global health problem with an escalating prevalence and severe implications for public health. New evidence indicates that long non-coding RNAs (lncRNAs) may play a pivotal role in regulating adipose tissue function and energy homeostasis across various species. However, the molecular mechanisms underlying obesity remain elusive.

Scope of review

This review discusses obesity and fat metabolism in general, highlighting the emerging importance of lncRNAs in modulating adipogenesis. It describes the regulatory networks, latest tools, techniques, and approaches to enhance our understanding of obesity and its lncRNA-mediated epigenetic regulation in humans and Drosophila.

Major conclusions

This review analyses large datasets of human and Drosophila lncRNAs from published databases and literature with experimental evidence supporting lncRNAs role in fat metabolism. It concludes that lncRNAs play a crucial role in obesity-related metabolism. Cross-species comparisons highlight the relevance of Drosophila findings to human obesity, emphasizing their potential role in adipose tissue biology. Furthermore, it discusses how recent technological advancements and multi-omics data integration enhance our capacity to characterize lncRNAs and their function. Additionally, this review briefly touches upon innovative methodologies like experimental evolution and advanced sequencing technologies for identifying novel genes and lncRNA regulators in Drosophila, which can potentially contribute to obesity research.

The Extract of Humulus japonicus Inhibits Lipogenesis and Promotes Lipolysis via PKA/p38 Signaling

INTRODUCTION

Previous research has shown that an aqueous extract of Humulus japonicus (EH) can ameliorate hypertension, nonalcoholic fatty liver disease, and oxidative stress in adipocytes by activating the thermogenic pathway. However, the effects of an ethanol (30%) extract of EH on obesity are unknown.

METHODS

Various protein expression levels in fully differentiated 3T3-L1 adipocytes were assessed by Western blotting. Lipid deposition in 3T3-L1 adipocytes was examined by oil red O staining. The MTT assay was used to evaluate adipocyte viability. Caspase 3 activity and glycerol release were determined using commercial assay kits.

RESULTS

In this study, we discovered that EH treatment inhibited lipogenesis and promoted lipolysis in both differentiated 3T3-L1 adipocytes and adipose tissue of mice fed a high-fat diet. EH treatment also increased phosphorylated protein kinase A (PKA) levels while reducing p38 phosphorylation. When H89, a PKA inhibitor, was used, the effects of EH on lipogenic lipid accumulation and lipolysis in 3T3-L1 adipocytes were eliminated. Treatment with luteolin 7-O-β-d-glucoside (LU), the major active compound in EH, also suppressed lipid deposition and p38 phosphorylation but enhanced lipolysis in 3T3-L1 adipocytes. These changes were abrogated by H89.

CONCLUSION

These findings indicate that EH containing LU reduces lipogenesis and stimulates lipolysis via the PKA/p38 signaling pathway, leading to an improvement in obesity in mice. Therefore, our study suggested that EH could be a promising therapeutic agent for treating obesity.

Protein-energy restriction-induced lipid metabolism disruption causes stable-to-progressive disease shift in Mycobacterium avium-infected female mice

BACKGROUND

Disease susceptibility and progression of Mycobacterium avium complex pulmonary disease (MAC-PD) is associated with multiple factors, including low body mass index (BMI). However, the specific impact of low BMI on MAC-PD progression remains poorly understood. This study aims to examine the progression of MAC-PD in the context of low BMI, utilising a disease-resistant mouse model.

METHODS

We employed a MAC infection-resistant female A/J mouse model to compare the progression of MAC-PD under two dietary conditions: one group was fed a standard protein diet, representing protein-energy unrestricted conditions, and the other was fed a low protein diet (LPD), representing protein-energy restriction.

FINDINGS

Our results reveal that protein-energy restriction significantly exacerbates MAC-PD progression by disrupting lipid metabolism. Mice fed an LPD showed elevated fatty acid levels and related gene expressions in lung tissues, similar to findings of increased fatty acids in the serum of patients who exhibited the MAC-PD progression. These mice also exhibited increased CD36 expression and lipid accumulation in macrophages upon MAC infection. In vitro experiments emphasised the crucial role of CD36-mediated palmitic acid uptake in bacterial proliferation. Importantly, in vivo studies demonstrated that administering anti-CD36 antibody to LPD-fed A/J mice reduced macrophage lipid accumulation and impeded bacterial growth, resulting in remarkable slowing disease progression.

INTERPRETATION

Our findings indicate that the metabolic status of host immune cells critically influences MAC-PD progression. This study highlights the potential of adequate nutrient intake in preventing MAC-PD progression, suggesting that targeting CD36-mediated pathways might be a host-directed therapeutic strategy to managing MAC infection.

FUNDING

This research was funded by the National Research Foundation of Korea, the Korea Research Institute of Bioscience and Biotechnology, and the Korea National Institute of Health.

Dietary Erucic Acid Induces Fat Accumulation, Hepatic Oxidative Damage, and Abnormal Lipid Metabolism in Nile Tilapia (Oreochromis niloticus)

Erucic acid (EA) in rapeseed oil has adverse effects on terrestrial animal and fish health. However, its antinutritional role in fish remains unclear due to the limited information on EA. Therefore, this study was conducted to assess the impact of EA on growth performance, antioxidative capacity, fatty acid profile, and lipid metabolism in tilapia. Six diets containing different amounts of EA (0, 3, 6, 12, 20, and 27 g/kg diet) were fed to tilapia (initial weight: 3.01 ± 0.01 g) for 8 weeks. The results exhibited that dietary EA did not affect growth performance but remarkedly increased the crude lipid contents (in the whole body, liver, and muscle). It also markedly increased the levels of low-density lipoprotein cholesterol, total cholesterol, nonesterified fatty acids, and triglyceride in the liver and serum in a dose-dependent manner. The EA groups had lower values of total superoxide dismutase, total antioxidant capacity, catalase, and higher activities of aspartate aminotransferase and alanine aminotransferase, as dietary EA levels increased. Feeding fish with diets containing EA (20 and 27 g/kg diet) significantly increased the malondialdehyde content. Moreover, dietary EA greatly altered the fatty acid profile in the liver and muscle. It especially elevated the percentages of C18 : 2n-6, C20 : 1n-9, and C22 : 1n-9 while decreasing the C18 : 0 and C16 : 0 levels. When the levels of EA in diets were 12, 20, and 27 g/kg, genes correlated with lipophagy, lipolysis, and β-oxidation were significantly reduced. Meanwhile, genes concerned in triglyceride synthesis were largely increased in the liver and muscle. In summary, high-dose EA (20 g/kg diet) in the diets significantly induced fat accumulation, hepatic oxidative damage, and abnormal lipid metabolism in tilapia. The current findings expand our understanding on the antinutritional role of EA in lipid homeostasis and fish health.

Positive Effects of Physical Activity on Insulin Signaling

Physical activity is integral to metabolic health, particularly in addressing insulin resistance and related disorders such as type 2 diabetes mellitus (T2DM). Studies consistently demonstrate a strong association between physical activity levels and insulin sensitivity. Regular exercise interventions were shown to significantly improve glycemic control, highlighting exercise as a recommended therapeutic strategy for reducing insulin resistance. Physical inactivity is closely linked to islet cell insufficiency, exacerbating insulin resistance through various pathways including ER stress, mitochondrial dysfunction, oxidative stress, and inflammation. Conversely, physical training and exercise preserve and restore islet function, enhancing peripheral insulin sensitivity. Exercise interventions stimulate β-cell proliferation through increased circulating levels of growth factors, further emphasizing its role in maintaining pancreatic health and glucose metabolism. Furthermore, sedentary lifestyles contribute to elevated oxidative stress levels and ceramide production, impairing insulin signaling and glucose metabolism. Regular exercise induces anti-inflammatory responses, enhances antioxidant defenses, and promotes mitochondrial function, thereby improving insulin sensitivity and metabolic efficiency. Encouraging individuals to adopt active lifestyles and engage in regular exercise is crucial for preventing and managing insulin resistance and related metabolic disorders, ultimately promoting overall health and well-being.

Genetic deletion of hormone-sensitive lipase in mice reduces cerebral blood flow but does not aggravate the impact of diet-induced obesity on memory

Hormone-sensitive lipase (HSL) is active throughout the brain and its genetic ablation impacts brain function. Its activity in the brain was proposed to regulate bioactive lipid availability, namely eicosanoids that are inflammatory mediators and regulate cerebral blood flow (CBF). We aimed at testing whether HSL deletion increases susceptibility to neuroinflammation and impaired brain perfusion upon diet-induced obesity. HSL-/-, HSL+/-, and HSL+/+ mice of either sex were fed high-fat diet (HFD) or control diet for 8 weeks, and then assessed in behavior tests (object recognition, open field, and elevated plus maze), metabolic tests (insulin and glucose tolerance tests and indirect calorimetry in metabolic cages), and CBF determination by arterial spin labeling (ASL) magnetic resonance imaging (MRI). Immunofluorescence microscopy was used to determine coverage of blood vessels, and morphology of astrocytes and microglia in brain slices. HSL deletion reduced CBF, most prominently in cortex and hippocampus, while HFD feeding only lowered CBF in the hippocampus of wild-type mice. CBF was positively correlated with lectin-stained vessel density. HSL deletion did not exacerbate HFD-induced microgliosis in the hippocampus and hypothalamus. HSL-/- mice showed preserved memory performance when compared to wild-type mice, and HSL deletion did not significantly aggravate HFD-induced memory impairment in object recognition tests. In contrast, HSL deletion conferred protection against HFD-induced obesity, glucose intolerance, and insulin resistance. Altogether, this study points to distinct roles of HSL in periphery and brain during diet-induced obesity. While HSL-/- mice were protected against metabolic syndrome development, HSL deletion reduced brain perfusion without leading to aggravated HFD-induced neuroinflammation and memory dysfunction.

Endotoxin-induced alterations of adipose tissue function: a pathway to bovine metabolic stress

During the periparturient period, dairy cows exhibit negative energy balance due to limited appetite and increased energy requirements for lactogenesis. The delicate equilibrium between energy availability and expenditure puts cows in a state of metabolic stress characterized by excessive lipolysis in white adipose tissues (AT), increased production of reactive oxygen species, and immune cell dysfunction. Metabolic stress, especially in AT, increases the risk for metabolic and inflammatory diseases. Around parturition, cows are also susceptible to endotoxemia. Bacterial-derived toxins cause endotoxemia by promoting inflammatory processes and immune cell infiltration in different organs and systems while impacting metabolic function by altering lipolysis, mitochondrial activity, and insulin sensitivity. In dairy cows, endotoxins enter the bloodstream after overcoming the defense mechanisms of the epithelial barriers, particularly during common periparturient conditions such as mastitis, metritis, and pneumonia, or after abrupt changes in the gut microbiome. In the bovine AT, endotoxins induce a pro-inflammatory response and stimulate lipolysis in AT, leading to the release of free fatty acids into the bloodstream. When excessive and protracted, endotoxin-induced lipolysis can impair adipocyte's insulin signaling pathways and lipid synthesis. Endotoxin exposure can also induce oxidative stress in AT through the production of reactive oxygen species by inflammatory cells and other cellular components. This review provides insights into endotoxins' impact on AT function, highlighting the gaps in our knowledge of the mechanisms underlying AT dysfunction, its connection with periparturient cows' disease risk, and the need to develop effective interventions to prevent and treat endotoxemia-related inflammatory conditions in dairy cattle.

Metformin improves obesity-related oligoasthenospermia via regulating the expression of HSL in testis in mice

Researches have proposed that obesity might contribute to development of oligoasthenospermia. This study was performed to confirm whether obesity contributes to oligoasthenospermia as well as the underlying mechanisms in mice fed with a high fat diet (HFD). Meanwhile, the actions of metformin, a drug of well-known weight-lowering effect, on sperm quality in obese mice were investigated. Our results showed that HFD feeding reduced sperm quality and steroid hormone levels in mice, associated with disruptions in testicular histomorphology and spermatogenesis. Moreover, obesity increased sperm apoptosis. These effects could be prevented by metformin treatment in HFD-fed mice. Mechanistically, an increasement in lipid contents associated with decreased hormone-sensitive lipase (HSL) protein expression in testes in HFD-fed mice was observed, which could be improved by metformin treatment. Then, the model of TM4 mouse Sertoli cells stimulated with palmitic acid (PA) was used to investigate the potential effect of lipid retention on testicular apoptosis and sperm quality reduction. In consistent, PA exposure elevated lipid contents as well as apoptosis in TM4 cells, which could also be improved by metformin treatment. Of note, the protein expression of HSL was reduced stimulated by PA in TM4 cells, also rescued by metformin. Then, anti-apoptosis effect of metformin would be lost with the deficiency of HSL. In summary, our study propose that obesity contributes to oligoasthenospermia by increasing sperm apoptosis induced by impaired lipid hydrolysis due to HSL down-regulation, which could be prevented with metformin treatment via regulating the expression of HSL in testis in mice.

Impact of Flaxseed Oil Supplementation on Tobacco Dependence, Craving, and Haematological Parameters in Tobacco-Dependent Subjects

Background Tobacco is prevalently used in smoking or smokeless forms and remains a major public health concern worldwide, with its adverse effects on overall health. Omega-3 fatty acid (FA) has shown its promising effects in various health conditions. Objective The purpose of this study was to evaluate the effect of flaxseed oil (omega-3 supplementation) on tobacco dependence, craving, withdrawal symptoms, and haematological parameters in tobacco users. Methods In this randomised, single-blind, placebo-controlled study, 104 tobacco users (54 in the omega-3 group and 50 in the placebo group) were supplemented with 10 ml of food-grade flaxseed oil and 10 ml of placebo for six months, respectively. Their demographics, frequency of daily tobacco use, tobacco dependence, tobacco craving, tobacco withdrawal symptoms, and complete blood count (CBC) were assessed at baseline (before intervention) and after a six-month intervention. Results The demographic characteristics of the two groups were similar except for gender at baseline. There were 50 males and four females in the omega-3 group, while there were 42 males and eight females in the placebo group. After a six-month flaxseed oil intervention, BMI values showed a significant reduction (p = 0.0081) in the omega-3 group when compared to baseline; however, CBC parameters did not show any significant changes when comparing baseline to follow-up values. On the contrary, haemoglobin and red blood cells (RBCs) showed significant changes when comparing the follow-ups of the omega-3 group with the placebo group, indicating p = 0.0016 and p = 0.0163, respectively. Also, omega-3 effectively decreased daily tobacco use frequency (p<0.0001), tobacco dependence (p<0.0001), and craving (p<0.0001). Conclusion Supplementation of 10 ml of flaxseed oil per day (omega-3 FA) for six months significantly reduced tobacco dependence and cravings. Additionally, the flaxseed oil supplementation effectively reduced the frequency of daily tobacco intake and modulated tobacco withdrawal symptoms. Thus, our results suggest that flaxseed oil supplementation is a useful adjunct for tobacco users who intend to quit tobacco use.

Functionally conserved PPARG exonic circRNAs enhance intramuscular fat deposition by regulating PPARG and HSL

Circular RNAs (circRNA) are a kind of endogenous biological macromolecules that play significant roles in many biological processes, including adipogenesis, a precisely orchestrated process that is mediated by a large number of factors. Among them, peroxisome proliferator-activated receptor gamma (PPARG), is undoubtedly the most important regulator of adipocyte development in all types of adipose tissue. The formation of intramuscular fat (IMF), is a key factor that influences the meat quality in livestock animals. PPARG has been demonstrated to show a positive correlation with IMF deposition although the regulatory mechanism involved is not known. This study demonstrates that PPARG mediates IMF deposition by producing multiple exonic circRNAs (circPPARGs). Three circPPARGs promote adipogenic differentiation and inhibit the proliferation of intramuscular preadipocytes and these effects are conserved across several species including buffaloes, cattle and mice. Notably, circPPARG1 interacts with PPARG protein to inhibit the transcription of hormone sensitive lipase (HSL) involved in lipolysis. In addition, the positive effects of circPPARG1 on IMF deposition were identified in mice in vivo. Thus, PPARG drives IMF deposition, not only through the common transcription factor pathway, but also by producing circRNAs. This study provides new insights into our understanding of the regulatory mechanisms of PPARG in IMF deposition.

The Checkpoints of Intestinal Fat Absorption in Obesity

In this chapter, intestinal lipid transport, which plays a central role in fat homeostasis and the development of obesity in addition to the mechanisms of fatty acids and monoacylglycerol absorption in the intestinal lumen and reassembly of these within the enterocyte was described. A part of the resynthesized triglycerides (triacylglycerols; TAG) is repackaged in the intestine to form the hydrophobic core of chylomicrons (CMs). These are delivered as metabolic fuels, essential fatty acids, and other lipid-soluble nutrients, from enterocytes to the peripheral tissues following detachment from the endoplasmic reticulum membrane. Moreover, the attitudes of multiple receptor functions in dietary lipid uptake, synthesis, and transport are highlighted. Additionally, intestinal fatty acid binding proteins (FABPs), which increase the cytosolic flux of fatty acids via intermembrane transfer in enterocytes, and the functions of checkpoints for receptor-mediated fatty acid signaling are debated. The importance of the balance between storage and secretion of dietary fat by enterocytes in determining the physiological fate of dietary fat, including regulation of blood lipid concentrations and energy balance, is mentioned. Consequently, promising checkpoints regarding how intestinal fat processing affects lipid homeostatic mechanisms and lipid stores in the body and the prevention of obesity-lipotoxicity due to excessive intestinal lipid absorption are evaluated. In this context, dietary TAG digestion, pharmacological inhibition of TAG hydrolysis, the regulation of long-chain fatty acid uptake traffic into adipocytes, intracellular TAG resynthesis, the enlargement of cytoplasmic lipid droplets in enterocytes and constitutional alteration of their proteome, CD36-mediated conversion of diet-derived fatty acid into cellular lipid messengers and their functions are discussed.

Moderate Effects of Hypoxic Training at Low and Supramaximal Intensities on Skeletal Muscle Metabolic Gene Expression in Mice

The muscle molecular adaptations to different exercise intensities in combination with hypoxia are not well understood. This study investigated the effect of low- and supramaximal-intensity hypoxic training on muscle metabolic gene expression in mice. C57BL/6 mice were divided into two groups: sedentary and training. Training consisted of 4 weeks at low or supramaximal intensity, either in normoxia or hypoxia (FiO2 = 0.13). The expression levels of genes involved in the hypoxia signaling pathway (Hif1a and Vegfa), the metabolism of glucose (Gys1, Glut4, Hk2, Pfk, and Pkm1), lactate (Ldha, Mct1, Mct4, Pdh, and Pdk4) and lipid (Cd36, Fabp3, Ucp2, Hsl, and Mcad), and mitochondrial energy metabolism and biogenesis (mtNd1, mtNd6, CytC, CytB, Pgc1a, Pgc1β, Nrf1, Tfam, and Cs) were determined in the gastrocnemius muscle. No physical performance improvement was observed between groups. In normoxia, supramaximal intensity training caused upregulation of major genes involved in the transport of glucose and lactate, fatty acid oxidation, and mitochondrial biogenesis, while low intensity training had a minor effect. The exposure to hypoxia changed the expression of some genes in the sedentary mice but had a moderate effect in trained mice compared to respective normoxic mice. In hypoxic groups, low-intensity training increased the mRNA levels of Mcad and Cs, while supramaximal intensity training decreased the mRNA levels of Mct1 and Mct4. The results indicate that hypoxic training, regardless of exercise intensity, has a moderate effect on muscle metabolic gene expression in healthy mice.

Catechin with Lactic Acid Bacteria Starters Enhances the Antiobesity Effect of Kimchi

The antiobesity effects of kimchi with catechin and lactic acid bacteria as starters were studied in C57BL/6 mice with high-fat diet (HFD)-induced obesity. We prepared four types of kimchi: commercial kimchi, standard kimchi, green tea functional kimchi, and catechin functional kimchi (CFK). Body weight and weight of adipose tissue were significantly lower in the kimchi-treated groups than in the HFD and Salt (HFD +1.5% NaCl) groups. In addition, in the CFK group, the serum levels of triglycerides, total cholesterol, and low-density lipoprotein cholesterol were significantly lower and those of high-density lipoprotein cholesterol were markedly higher than the corresponding levels in the HFD and Salt groups. Moreover, CFK reduced fat cells and crown-like structures in the liver and epididymal fat tissues. The protein expression of adipo/lipogenesis-related genes in the liver and epididymal fat tissues was significantly lower (1.90-7.48-fold) in the CFK group than in the HFD and Salt groups, concurrent with upregulation of lipolysis-related genes (1.71-3.38-fold) and downregulation of inflammation-related genes (3.17-5.06-fold) in epididymal fat tissues. In addition, CFK modulated the gut microbiomes of obese mice by increasing the abundance of Bacteroidetes (7.61%), while in contrast, Firmicutes (82.21%) decreased. In addition, the presence of the Erysipelotrichaceae (8.37%) family in the CFK group decreased, while the number of beneficial bacteria of the families, Akkermansiaceae (6.74%), Lachnospiraceae (14.95%), and Lactobacillaceae (38.41%), increased. Thus, CFK exhibited an antiobesity effect through its modulation of lipid metabolism and the microbiome.

TLR4 in POMC neurons regulates thermogenesis in a sex-dependent manner

The rising prevalence of obesity has become a worldwide health concern. Obesity usually occurs when there is an imbalance between energy intake and energy expenditure. However, energy expenditure consists of several components, including metabolism, physical activity, and thermogenesis. Toll-like receptor 4 (TLR4) is a transmembrane pattern recognition receptor, and it is abundantly expressed in the brain. Here, we showed that pro-opiomelanocortin (POMC)-specific deficiency of TLR4 directly modulates brown adipose tissue thermogenesis and lipid homeostasis in a sex-dependent manner. Deleting TLR4 in POMC neurons is sufficient to increase energy expenditure and thermogenesis resulting in reduced body weight in male mice. POMC neuron is a subpopulation of tyrosine hydroxylase neurons and projects into brown adipose tissue, which regulates the activity of sympathetic nervous system and contributes to thermogenesis in POMC-TLR4-KO male mice. By contrast, deleting TLR4 in POMC neurons decreases energy expenditure and increases body weight in female mice, which affects lipolysis of white adipose tissue (WAT). Mechanistically, TLR4 KO decreases the expression of the adipose triglyceride lipase and lipolytic enzyme hormone-sensitive lipase in WAT in female mice. Furthermore, the function of immune-related signaling pathway in WAT is inhibited because of obesity, which exacerbates the development of obesity reversely. Together, these results demonstrate that TLR4 in POMC neurons regulates thermogenesis and lipid balance in a sex-dependent manner.

Changes in Lipid Metabolism Enzymes in Rat Epididymal Fat after Chronic Central Leptin Infusion Are Related to Alterations in Inflammation and Insulin Signaling

Leptin inhibits food intake and reduces the size of body fat depots, changing adipocyte sensitivity to insulin to restrain lipid accrual. This adipokine may modulate the production of cytokines that could diminish insulin sensitivity, particularly in visceral adipose tissue. To explore this possibility, we examined the effects of chronic central administration of leptin on the expression of key markers of lipid metabolism and its possible relationship with changes in inflammatory- and insulin-signaling pathways in epididymal adipose tissue. Circulating non-esterified fatty acids and pro- and anti-inflammatory cytokines were also measured. Fifteen male rats were divided into control (C), leptin (L, icv, 12 μg/day for 14 days), and pair-fed (PF) groups. We found a decrease in the activity of glucose-6-phosphate dehydrogenase and malic enzyme in the L group, with no changes in the expression of lipogenic enzymes. A reduction in the expression of lipoprotein lipase and carnitine palmitoyl-transferase-1A, together with a decrease in the phosphorylation of insulin-signaling targets and a low-grade inflammatory pattern, were detected in the epididymal fat of L rats. In conclusion, the decrease in insulin sensitivity and increased pro-inflammatory environment could regulate lipid metabolism, reducing epididymal fat stores in response to central leptin infusion.

Effects of Starvation and Refeeding on Growth, Digestion, Nonspecific Immunity and Lipid-Metabolism-Related Genes in Onychostoma macrolepis

The present research was conducted to assess the influences of starvation and refeeding on growth, nonspecific immunity and lipid metabolic adaptation in Onychostoma macrolepis. To date, there have been no similar reports in O. macrolepis. The fish were randomly assigned into two groups: control group (continuous feeding for six weeks) and starved–refed group (starvation for three weeks and then refeeding for three weeks). After three weeks of starvation, the results showed that the body weight (BW, 1.44 g), condition factor (CF, 1.17%), visceral index (VSI, 3.96%), hepatopancreas index (HSI, 0.93%) and intraperitoneal fat index (IPFI, 0.70%) of fish were significantly lower compared to the control group (BW, 5.72 g; CF, 1.85%; VSI, 6.35%; HSI, 2.04%; IPFI, 1.92%) (p < 0.05). After starvation, the serum triglyceride (TG, 0.83 mmol/L), total cholesterol (T-GHOL, 1.15 mmol/L), high-density lipoprotein (HDL, 1.13 mmol/L) and low-density lipoprotein (LDL, 0.46 mmol/L) concentrations were significantly lower than those in the control group (TG, 1.69 mmol/L; T-GHOL, 1.86 mmol/L; HDL, 1.62 mmol/L; LDL, 0.63 mmol/L) (p < 0.05). The activities of intestinal digestive enzymes (amylase, lipase and protease) in the starved-refed group were significantly lower than those in the control group after three weeks of starvation (p < 0.05). The highest activities of immune enzymes such as lysozyme (LZM), acid phosphate (ACP), alkaline phosphate (ALP), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) in the hepatopancreas were presented in the starved–refed group at second week, and significantly higher than those in the control group (p < 0.05). Meanwhile, starvation significantly improved intestinal immune enzymes activities (p < 0.05). the lowest TG contents and the highest expression levels of lipolysis genes including hormone-sensitive lipase (HSL) and carnitine palmitoyl transferase 1 isoform A (CPT-1A) appeared in the hepatopancreas, muscle and intraperitoneal fat after starvation, indicating the mobilization of fat reserves in these tissues (p < 0.05). After refeeding, the recovery of TG content might be mediated by the upregulation of the expression levels of lipogenesis genes such as sterol regulatory element binding protein 1 (SREBP1) and fatty acid synthase (FAS). Understanding the duration of physiological and metabolic changes in O. macrolepis and their reversibility or irreversibility to supplementary feeding response could provide valuable reference for the adaptability of O. macrolepis in large-scale culturing, proliferation and release.

Hypertrophy and ER Stress Induced by Palmitate Are Counteracted by Mango Peel and Seed Extracts in 3T3-L1 Adipocytes

A diet rich in saturated fatty acids (FAs) has been correlated with metabolic dysfunction and ROS increase in the adipose tissue of obese subjects. Thus, reducing hypertrophy and oxidative stress in adipose tissue can represent a strategy to counteract obesity and obesity-related diseases. In this context, the present study showed how the peel and seed extracts of mango (Mangifera indica L.) reduced lipotoxicity induced by high doses of sodium palmitate (PA) in differentiated 3T3-L1 adipocytes. Mango peel (MPE) and mango seed (MSE) extracts significantly lowered PA-induced fat accumulation by reducing lipid droplet (LDs) and triacylglycerol (TAGs) content in adipocytes. We showed that MPE and MSE activated hormone-sensitive lipase, the key enzyme of TAG degradation. In addition, mango extracts down-regulated the adipogenic transcription factor PPARγ as well as activated AMPK with the consequent inhibition of acetyl-CoA-carboxylase (ACC). Notably, PA increased endoplasmic reticulum (ER) stress markers GRP78, PERK and CHOP, as well as enhanced the reactive oxygen species (ROS) content in adipocytes. These effects were accompanied by a reduction in cell viability and the induction of apoptosis. Interestingly, MPE and MSE counteracted PA-induced lipotoxicity by reducing ER stress markers and ROS production. In addition, MPE and MSE increased the level of the anti-oxidant transcription factor Nrf2 and its targets MnSOD and HO-1. Collectively, these results suggest that the intake of mango extract-enriched foods in association with a correct lifestyle could exert beneficial effects to counteract obesity.

Mitochondrial phosphatidylethanolamine modulates UCP1 to promote brown adipose thermogenesis

Thermogenesis by uncoupling protein 1 (UCP1) is one of the primary mechanisms by which brown adipose tissue (BAT) increases energy expenditure. UCP1 resides in the inner mitochondrial membrane (IMM), where it dissipates membrane potential independent of adenosine triphosphate (ATP) synthase. Here, we provide evidence that phosphatidylethanolamine (PE) modulates UCP1-dependent proton conductance across the IMM to modulate thermogenesis. Mitochondrial lipidomic analyses revealed PE as a signature molecule whose abundance bidirectionally responds to changes in thermogenic burden. Reduction in mitochondrial PE by deletion of phosphatidylserine decarboxylase (PSD) made mice cold intolerant and insensitive to β3 adrenergic receptor agonist-induced increase in whole-body oxygen consumption. High-resolution respirometry and fluorometry of BAT mitochondria showed that loss of mitochondrial PE specifically lowers UCP1-dependent respiration without compromising electron transfer efficiency or ATP synthesis. These findings were confirmed by a reduction in UCP1 proton current in PE-deficient mitoplasts. Thus, PE performs a previously unknown role as a temperature-responsive rheostat that regulates UCP1-dependent thermogenesis.

Thermoneutral housing shapes hepatic inflammation and damage in mouse models of non-alcoholic fatty liver disease

Introduction

Inflammation is a common unifying factor in experimental models of non-alcoholic fatty liver disease (NAFLD) progression. Recent evidence suggests that housing temperature-driven alterations in hepatic inflammation correlate with exacerbated hepatic steatosis, development of hepatic fibrosis, and hepatocellular damage in a model of high fat diet-driven NAFLD. However, the congruency of these findings across other, frequently employed, experimental mouse models of NAFLD has not been studied.

Methods

Here, we examine the impact of housing temperature on steatosis, hepatocellular damage, hepatic inflammation, and fibrosis in NASH diet, methionine and choline deficient diet, and western diet + carbon tetrachloride experimental models of NAFLD in C57BL/6 mice.

Results

We show that differences relevant to NAFLD pathology uncovered by thermoneutral housing include: (i) augmented NASH diet-driven hepatic immune cell accrual, exacerbated serum alanine transaminase levels and increased liver tissue damage as determined by NAFLD activity score; (ii) augmented methionine choline deficient diet-driven hepatic immune cell accrual and increased liver tissue damage as indicated by amplified hepatocellular ballooning, lobular inflammation, fibrosis and overall NAFLD activity score; and (iii) dampened western diet + carbon tetrachloride driven hepatic immune cell accrual and serum alanine aminotransferase levels but similar NAFLD activity score.

Discussion

Collectively, our findings demonstrate that thermoneutral housing has broad but divergent effects on hepatic immune cell inflammation and hepatocellular damage across existing experimental NAFLD models in mice. These insights may serve as a foundation for future mechanistic interrogations focused on immune cell function in shaping NAFLD progression.

Cardiac metabolism in HFpEF: from fuel to signalling

Heart failure (HF) is marked by distinctive changes in myocardial uptake and utilization of energy substrates. Among the different types of HF, HF with preserved ejection fraction (HFpEF) is a highly prevalent, complex, and heterogeneous condition for which metabolic derangements seem to dictate disease progression. Changes in intermediate metabolism in cardiometabolic HFpEF-among the most prevalent forms of HFpEF-have a large impact both on energy provision and on a number of signalling pathways in the heart. This dual, metabolic vs. signalling, role is played in particular by long-chain fatty acids (LCFAs) and short-chain carbon sources [namely, short-chain fatty acids (SCFAs) and ketone bodies (KBs)]. LCFAs are key fuels for the heart, but their excess can be harmful, as in the case of toxic accumulation of lipid by-products (i.e. lipotoxicity). SCFAs and KBs have been proposed as a potential major, alternative source of energy in HFpEF. At the same time, both LCFAs and short-chain carbon sources are substrate for protein post-translational modifications and other forms of direct and indirect signalling of pivotal importance in HFpEF pathogenesis. An in-depth molecular understanding of the biological functions of energy substrates and their signalling role will be instrumental in the development of novel therapeutic approaches to HFpEF. Here, we summarize the current evidence on changes in energy metabolism in HFpEF, discuss the signalling role of intermediate metabolites through, at least in part, their fate as substrates for post-translational modifications, and highlight clinical and translational challenges around metabolic therapy in HFpEF.

Astragalus polysaccharide prevents heart failure-induced cachexia by alleviating excessive adipose expenditure in white and brown adipose tissue

BACKGROUND

Astragalus polysaccharide (APS) is a key active ingredient isolated from Astragalus membranaceus that has been reported to be a potential treatment for obesity and diabetes by regulating lipid metabolism and adipogenesis, alleviating inflammation, and improving insulin resistance. However, whether APS regulates lipid metabolism in the context of cachexia remains unclear. Therefore, this study analysed the effects of APS on lipid metabolism and adipose expenditure in a heart failure (HF)-induced cardiac cachexia rat model.  METHODS: A salt-sensitive hypertension-induced cardiac cachexia rat model was used in the present study. Cardiac function was detected by echocardiography. The histological features and fat droplets in fat tissue and liver were observed by H&E staining and Oil O Red staining. Immunohistochemical staining, Western blotting and RT‒qPCR were used to detect markers of lipolysis and adipose browning in white adipose tissue (WAT) and thermogenesis in brown adipose tissue (BAT). Additionally, sympathetic nerve activity and inflammation in adipose tissue were detected.

RESULTS

Rats with HF exhibited decreased cardiac function and reduced adipose accumulation as well as adipocyte atrophy. In contrast, administration of APS not only improved cardiac function and increased adipose weight but also prevented adipose atrophy and FFA efflux in HF-induced cachexia. Moreover, APS inhibited HF-induced lipolysis and browning of white adipocytes since the expression levels of lipid droplet enzymes, including HSL and perilipin, and beige adipocyte markers, including UCP-1, Cd137 and Zic-1, were suppressed after administration of APS. In BAT, treatment with APS inhibited PKA-p38 MAPK signalling, and these effects were accompanied by decreased thermogenesis reflected by decreased expression of UCP-1, PPAR-γ and PGC-1α and reduced FFA β-oxidation in mitochondria reflected by decreased Cd36, Fatp-1 and Cpt1. Moreover, sympathetic nerve activity and interleukin-6 levels were abnormally elevated in HF rats, and astragalus polysaccharide could inhibit their activity.

CONCLUSION

APS prevented lipolysis and adipose browning in WAT and decreased BAT thermogenesis. These effects may be related to suppressed sympathetic activity and inflammation. This study provides a potential approach to treat HF-induced cardiac cachexia.

Growth hormone stimulates lipolysis in mice but not in adipose tissue or adipocyte culture

The inhibitory effect of growth hormone (GH) on adipose tissue growth and the stimulatory effect of GH on lipolysis are well known, but the mechanisms underlying these effects are not completely understood. In this study, we revisited the effects of GH on adipose tissue growth and lipolysis in the lit/lit mouse model. The lit/lit mice are GH deficient because of a mutation in the GH releasing hormone receptor gene. We found that the lit/lit mice had more subcutaneous fat and larger adipocytes than their heterozygous lit/+ littermates and that these differences were partially reversed by 4-week GH injection. We also found that GH injection to the lit/lit mice caused the mature adipose tissue and adipocytes to reduce in size. These results demonstrate that GH inhibits adipose tissue growth at least in part by stimulating lipolysis. To determine the mechanism by which GH stimulates lipolysis, we cultured adipose tissue explants and adipocytes derived from lit/lit mice with GH and/or isoproterenol, an agonist of the beta-adrenergic receptors. These experiments showed that whereas isoproterenol, expectedly, stimulated potent lipolysis, GH, surprisingly, had no effect on basal lipolysis or isoproterenol-induced lipolysis in adipose tissue explants or adipocytes. We also found that both isoproterenol-induced lipolysis and phosphorylation of hormone-sensitive lipase were not different between lit/lit and lit/+ mice. Taken together, these results support the conclusion that GH has lipolytic effect in mice but argue against the notion that GH stimulates lipolysis by directly acting on adipocytes or by enhancing β-adrenergic receptors-mediated lipolysis.

Effects of Fermented Citrus Peel on Ameliorating Obesity in Rats Fed with High-Fat Diet

Although citrus peel is a waste material, it contains a variety of bioactive components. As our preliminary findings showed that citrus peels fermented with Saccharomyces cerevisiae T1 contained increased levels of anti-obesity flavonoids, the objective of this study was to prepare fermented citrus peel and to investigate its effect on ameliorating obesity in Sprague Dawley (SD) rats fed with a high-fat diet (HFD). After fermentation, the amounts of limonene, nobiletin and 3-methoxynobiletin in citrus peel were markedly increased. SD rats were fed with an HFD for 10 weeks, followed by fermented citrus peel-containing HFD (0.3% or 0.9% w/w) for 6 weeks. Compared with those fed with an HFD alone, lower levels of body weight, visceral fat, body fat percentage, blood triglyceride, total cholesterol, low-density lipoprotein, malondialdehyde and hepatic adipose accumulation were observed in rats fed with fermented citrus peel. In parallel, hepatic levels of acetyl-CoA carboxylase and fatty acid synthase were diminished, and the level of hormone sensitivity lipase in visceral fat was elevated. These results reveal fermented citrus peel is a promising natural product with beneficial effects of alleviating HFD-induced obesity.

Obese outbred mice only partially benefit from diet normalization or calorie restriction as preconception care interventions to improve metabolic health and oocyte quality

STUDY QUESTION

Can diet normalization or a calorie-restricted diet for 2 or 4 weeks be used as a preconception care intervention (PCCI) in Western-type diet-induced obese Swiss mice to restore metabolic health and oocyte quality?

SUMMARY ANSWER

Metabolic health and oocyte developmental competence was already significantly improved in the calorie-restricted group after 2 weeks, while obese mice that underwent diet normalization showed improved metabolic health after 2 weeks and improved oocyte quality after 4 weeks.

WHAT IS KNOWN ALREADY

Maternal obesity is linked with reduced metabolic health and oocyte quality; therefore, infertile obese women are advised to lose weight before conception to increase pregnancy chances. However, as there are no univocal guidelines and the specific impact on oocyte quality is not known, strategically designed studies are needed to provide fundamental insights in the importance of the type and duration of the dietary weight loss strategy for preconception metabolic health and oocyte quality.

STUDY DESIGN, SIZE, DURATION

Outbred female Swiss mice were fed a control (CTRL) or high-fat/high-sugar (HF/HS) diet. After 7 weeks, some of the HF mice were put on two different PCCIs, resulting in four treatment groups: (i) only control diet for up to 11 weeks (CTRL_CTRL), (ii) only HF diet for up to 11 weeks (HF_HF), (iii) switch at 7 weeks from an HF to an ad libitum control diet (HF_CTRL) and (iv) switch at 7 weeks from an HF to a 30% calorie-restricted control diet (HF_CR) for 2 or 4 weeks. Metabolic health and oocyte quality were assessed at 2 and 4 weeks after the start of the intervention (n = 8 mice/treatment/time point).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Changes in body weight were recorded. To study the impact on metabolic health, serum insulin, glucose, triglycerides, total cholesterol and alanine aminotransferase concentrations were measured, and glucose tolerance and insulin sensitivity were analyzed at PCCI Weeks 2 and 4. The quality of in vivo matured oocytes was evaluated by assessing intracellular lipid droplet content, mitochondrial activity and localization of active mitochondria, mitochondrial ultrastructure, cumulus cell targeted gene expression and oocyte in vitro developmental competence.

MAIN RESULTS AND THE ROLE OF CHANCE

Significant negative effects of an HF/HS diet on metabolic health and oocyte quality were confirmed (P < 0.05). HF_CTRL mice already showed restored body weight, serum lipid profile and glucose tolerance, similar to the CTRL_CTRL group after only 2 weeks of PCCI (P < 0.05 compared with HF_HF) while insulin sensitivity was not improved. Oocyte lipid droplet volume was reduced at PCCI Week 2 (P < 0.05 compared with HF_HF), while mitochondrial localization and activity were still aberrant. At PCCI Week 4, oocytes from HF_CTRL mice displayed significantly fewer mitochondrial ultrastructural abnormalities and improved mitochondrial activity (P < 0.05), while lipid content was again elevated. The in vitro developmental capacity of the oocytes was improved but did not reach the levels of the CTRL_CTRL mice. HF_CR mice completely restored cholesterol concentrations and insulin sensitivity already after 2 weeks. Other metabolic health parameters were only restored after 4 weeks of intervention with clear signs of fasting hypoglycemia. Although all mitochondrial parameters in HF_CR oocytes stayed aberrant, oocyte developmental competence in vitro was completely restored already after 2 weeks of intervention.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

In this study, we applied a relevant HF/HS Western-type diet to induce obesity in an outbred mouse model. Nevertheless, physiological differences should be considered when translating these results to the human setting. However, the in-depth study and follow-up of the metabolic health changes together with the strategic implementation of specific PCCI intervals (2 and 4 weeks) related to the duration of the mouse folliculogenesis (3 weeks), should aid in the extrapolation of our findings to the human setting.

WIDER IMPLICATIONS OF THE FINDINGS

Our study results with a specific focus on oocyte quality provide important fundamental insights to be considered when developing preconception care guidelines for obese metabolically compromised women wishing to become pregnant.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Flemish Research Fund (FWO-SB grant 1S25020N and FWO project G038619N). The authors declare there are no conflicts of interest.

Long-term exposure to environmental levels of phenanthrene induces emaciation-thirst disease-like syndromes in female mice

Phenanthrene (Phe) is a polycyclic aromatic hydrocarbon widely present in foods and drinking water. To explore the detrimental effects of Phe on body metabolism, female Kunming mice were treated with Phe in drinking water at concentrations of 0.05, 0.5 and 5 ng/mL. After exposure for 270 d, the animals exhibited dose-dependent reduced body weight and increased water consumption. The dose-dependent accumulation of Phe in the brain decreased hypothalamic neuron numbers, upregulated hypothalamic expression of anaplastic lymphoma kinase, elevated norepinephrine levels in white adipose tissue (WAT) and further activated lipolysis in WAT, leading to a reduction in fat mass. Brown adipose tissue formation was reduced, accompanied by the inhibition of the bone morphogenetic protein signaling pathway. A simultaneous reduced serum levels of antidiuretic hormone (arginine vasopressin) might be one of the reasons for increased water consumption. The present results indicate an environmental etiology and prevention way for the development of emaciation-thirst disease.

Approaches to Measuring the Activity of Major Lipolytic and Lipogenic Enzymes In Vitro and Ex Vivo

Since the 1950s, one of the goals of adipose tissue research has been to determine lipolytic and lipogenic activity as the primary metabolic pathways affecting adipocyte health and size and thus representing potential therapeutic targets for the treatment of obesity and associated diseases. Nowadays, there is a relatively large number of methods to measure the activity of these pathways and involved enzymes, but their applicability to different biological samples is variable. Here, we review the characteristics of mean lipogenic and lipolytic enzymes, their inhibitors, and available methodologies for assessing their activity, and comment on the advantages and disadvantages of these methodologies and their applicability in vivo, ex vivo, and in vitro, i.e., in cells, organs and their respective extracts, with the emphasis on adipocytes and adipose tissue.

Genome of Laudakia sacra Provides New Insights into High-Altitude Adaptation of Ectotherms

Anan’s rock agama (Laudakia sacra) is a lizard species endemic to the harsh high-altitude environment of the Qinghai–Tibet Plateau, a region characterized by low oxygen tension and high ultraviolet (UV) radiation. To better understand the genetic mechanisms underlying highland adaptation of ectotherms, we assembled a 1.80-Gb L. sacra genome, which contained 284 contigs with an N50 of 20.19 Mb and a BUSCO score of 93.54%. Comparative genomic analysis indicated that mutations in certain genes, including HIF1A, TIE2, and NFAT family members and genes in the respiratory chain, may be common adaptations to hypoxia among high-altitude animals. Compared with lowland reptiles, MLIP showed a convergent mutation in L. sacra and the Tibetan hot-spring snake (Thermophis baileyi), which may affect their hypoxia adaptation. In L. sacra, several genes related to cardiovascular remodeling, erythropoiesis, oxidative phosphorylation, and DNA repair may also be tailored for adaptation to UV radiation and hypoxia. Of note, ERCC6 and MSH2, two genes associated with adaptation to UV radiation in T. baileyi, exhibited L. sacra-specific mutations that may affect peptide function. Thus, this study provides new insights into the potential mechanisms underpinning high-altitude adaptation in ectotherms and reveals certain genetic generalities for animals’ survival on the plateau.

Cloning and Molecular Characterization of HSL and Its Expression Pattern in HPG Axis and Testis during Different Stages in Bactrian Camel

Hormone-sensitive lipase (HSL) is a key enzyme in animal fat metabolism and is involved in the rate-limiting step of catalyzing the decomposition of fat and cholesterol. It also plays an important regulatory role in maintaining seminiferous epithelial structure, androgen synthesis and primordial germ cell differentiation. We previously reported that HSL is involved the synthesis of steroids in Bactrian camels, although it is unclear what role it plays in testicular development. The present study was conducted to characterize the biological function and expression pattern of the HSL gene in the hypothalamic pituitary gonadal (HPG) axis and the development of testis in Bactrian camels. We analyzed cloning of the cDNA sequence of the HSL gene of Bactrian camels by RT-PCR, as well as the structural features of HSL proteins, using bioinformatics software, such as ProtParam, TMHMM, Signal P 4.1, SOPMA and MEGA 7.0. We used qRT-PCR, Western blotting and immunofluorescence staining to clarify the expression pattern of HSL in the HPG axis and testis of two-week-old (2W), two-year-old (2Y), four-year-old (4Y) and six-year-old (6Y) Bactrian camels. According to sequence analysis, the coding sequence (CDS) region of the HSL gene is 648 bp in length and encodes 204 amino acids. According to bioinformatics analysis, the nucleotide and amino acid sequence of Bactrian camel HSL are most similar to those of Camelus pacos and Camelusdromedarius, with the lowest sequence similarity with Mus musculus. In adult Bactrian camel HPG axis tissues, both HSL mRNA and protein expression were significantly higher in the testis than in other tissues (hypothalamus, pituitary and pineal tissues) (p < 0.05). The expression of mRNA in the testis increased with age and was the highest in six-year-old testis (p < 0.01). The protein expression levels of HSL in 2Y and 6Y testis were clearly higher than in 2W and 4Y testis tissues (p < 0.01). Immunofluorescence results indicate that the HSL protein was mainly localized in the germ cells, Sertoli cells and Leydig cells from Bactrian camel testis, and strong positive signals were detected in epididymal epithelial cells, basal cells, spermatocytes and smooth muscle cells, with partially expression in hypothalamic glial cells, pituitary suspensory cells and pineal cells. According to the results of gene ontology (GO) analysis enrichment, HSL indirectly regulates the anabolism of steroid hormones through interactions with various targets. Therefore, we conclude that the HSL gene may be associated with the development and reproduction of Bactrian camels in different stages of maturity, and these results will contribute to further understanding of the regulatory mechanisms of HSL in Bactrian camel reproduction.

Association of irisin levels with cardiac magnetic resonance, inflammatory, and biochemical parameters in patients with chronic heart failure versus controls

BACKGROUND AND AIMS

Chronic heart failure (CHF) represents a significant cause of morbidity and mortality globally. Metabolic maladaptation has proven to be critical in the progression of this condition. Preclinical studies have shown that irisin, an adipomyokine involved in metabolic regulations, can induce positive cardioprotective effects by improving cardiac remodeling, cardiomyocyte viability, calcium delivery, and reducing inflammatory mediators. However, data on clinical studies identifying the associations between irisin levels and functional imaging parameters are scarce in CHF patients. The objective of this study was to determine the association of irisin levels with cardiac imaging measurements through cardiac magnetic resonance, inflammatory markers, and biochemical parameters in patients with CHF compared with control subjects.

METHODS AND RESULTS

Thirty-two subjects diagnosed with CHF and thirty-two healthy controls were evaluated in a cross-sectional study. Serum irisin levels were significantly lower in patients with CHF than in controls. This is the first study to report a significant positive correlation between irisin levels and cardiac magnetic resonance parameters such as left ventricular ejection fraction, fraction shortening, and global radial strain. A negative correlation was demonstrated between irisin levels and brain natriuretic peptide, insulin levels, and Homeostatic model assessment for insulin resistance index. We did not observe significant correlations between irisin levels and inflammatory cytokines.

CONCLUSIONS

Given the importance of fraction shortening and global radial strain as accurate markers of ventricular wall motion, these results support the hypothesis that irisin may play an essential role in maintaining an adequate myocardial wall architecture, deformation, and thickness.

Relationship between Plasma Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) Level and Proteome Profile of Cows

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a pleiotropic and multifunctional neuropeptide; it takes part in the regulation of various physiological processes, such as feeding, reproduction, catecholamine synthesis, thermoregulation, motor activity, brain development and neuronal survival. Since PACAP plays important regulatory roles, we hypothesized that the level of PACAP in blood is associated with expression of other proteins, which are involved in different metabolic pathways. The objective of the present study was to compare plasma protein profiles of cows with high and low plasma PACAP levels. Differential proteome analyses were performed by two-dimensional gel electrophoresis (2D-PAGE) followed by tryptic digestion and protein identification by liquid chromatography−mass spectrometry (LC-MS). A total of 210 protein spots were detected, and 16 protein spots showed statistically significant differences (p < 0.05) in the expression levels between groups. Ten spots showed a higher intensity in the high-PACAP-concentration group, while six spots were more abundant in the low-PACAP-concentration group. The functions of the differentially expressed proteins indicate that the PACAP level of plasma is related to the lipid metabolism and immune status of cattle.

PKA/ATGL signaling pathway is involved in ER stress-mediated lipolysis in adipocytes of grass carp (Ctenopharyngodon idella)

The relationship between endoplasmic reticulum stress (ER stress) and lipolysis in mammals has been widely studied, but it is relatively scarce in fish. The present study used grass carp Ctenopharyngodon idella as a model to investigate the effect of ER stress on lipolysis in adipocytes of fish. We found that ER stress evoked by tunicamycin (TM) treatment significantly induced lipolysis in adipocytes. Subsequently, in order to further investigate whether protein kinase A (PKA) is involved in ER stress-induced lipolysis, we treated adipocytes with PKA activator forskolin and inhibitor H89. The results showed that the mechanism was related to the activation of PKA, especially the catalytic subunit PRKACBa. Notably, we also found that PKA regulates lipolysis by targeting mRNA level and protein and enzyme activities of adipotriglyceride lipase (ATGL). Taken together, our findings suggest that PKA/ATGL signaling pathway is involved in ER stress-mediated lipolysis of grass carp adipocytes. It provides a theoretical basis for further study on the mechanism of lipolysis in fish and other vertebrates.

Adipocyte Phenotype Flexibility and Lipid Dysregulation

The prevalence of obesity and associated cardiometabolic diseases continues to rise, despite efforts to improve global health. The adipose tissue is now regarded as an endocrine organ since its multitude of secretions, lipids chief among them, regulate systemic functions. The loss of normal adipose tissue phenotypic flexibility, especially related to lipid homeostasis, appears to trigger cardiometabolic pathogenesis. The goal of this manuscript is to review lipid balance maintenance by the lean adipose tissue’s propensity for phenotype switching, obese adipose tissue’s narrower range of phenotype flexibility, and what initial factors account for the waning lipid regulatory capacity. Metabolic, hypoxic, and inflammatory factors contribute to the adipose tissue phenotype being made rigid. A better grasp of normal adipose tissue function provides the necessary context for recognizing the extent of obese adipose tissue dysfunction and gaining insight into how pathogenesis evolves.

DECR1 directly activates HSL to promote lipolysis in cervical cancer cells

Fatty acids have a high turnover rate in cancer cells to supply energy for tumor growth and proliferation. Lipolysis is particularly important for the regulation of fatty acid homeostasis and in the maintenance of cancer cells. In the current study, we explored how 2,4-Dienoyl-CoA reductase (DECR1), a short-chain dehydrogenase/reductase associated with mitochondrial and cytoplasmic compartments, promotes cancer cell growth. We report that DECR1 overexpression significantly reduced the triglyceride (TAG) content in HeLa cells; conversely, DECR1 silencing increased intracellular TAG content. Subsequently, our experiments demonstrate that DECR1 promotes lipolysis via effects on hormone sensitive lipase (HSL). The direct interaction of DECR1 with HSL increases HSL phosphorylation and activity, facilitating the translocation of HSL to lipid droplets. The ensuing enhancement of lipolysis thus increases the release of free fatty acids. Downstream effects include the promotion of cervical cancer cell migration and growth, associated with the enhanced levels of p62 protein. In summary, high levels of DECR1 serves to enhance lipolysis and the release of fatty acid energy stores to support cervical cancer cell growth.

The effect of adenosine monophosphate-activated protein kinase on lipolysis in adipose tissue: an historical and comprehensive review

CONTEXT

Lipolysis is one of the most important pathways for energy management, its control in the adipose tissue (AT) is a potential therapeutic target for metabolic diseases. Adenosine Mono Phosphate-activated Protein Kinase (AMPK) is a key regulatory enzyme in lipids metabolism and a potential target for diabetes and obesity treatment.

OBJECTIVE

The aim of this work is to analyse the existing information on the relationship of AMPK and lipolysis in the AT.

METHODS

A thorough search of bibliography was performed in the databases Scopus and Web of Knowledge using the terms lipolysis, adipose tissue, and AMPK, the unrelated publications were excluded, and the documents were analysed.

RESULTS

Sixty-three works were found and classified in 3 categories: inhibitory effects, stimulatory effect, and diverse relationships; remarkably, the newest researches support an upregulating relationship of AMPK over lipolysis.

CONCLUSION

The most probable reality is that the relationship AMPK-lipolysis depends on the experimental conditions.

MiR-218-5p Affects Subcutaneous Adipogenesis by Targeting ACSL1, A Novel Candidate for Pig Fat Deposition

As a centre enzyme in fatty acid activation, acyl-CoA synthetase long-chain family member 1 (ACSL1) plays an important role in body lipid homeostasis. However, the functions of ACSL1 in the subcutaneous adipogenesis of pigs are largely unknown. In the present study, we found that the expression of ACSL1 significantly increased during the process of porcine preadipocyte differentiation. Moreover, silencing of ACSL1 in preadipocytes decreased levels of triglyceride and adipogenic-related markers, including FABP4, APOE, and FASN (p < 0.01), and simultaneously increased levels of lipolytic-related markers, such as ATGL and HSL (p < 0.05). Conversely, overexpression of ACSL1 in preadipocytes increased levels of triglyceride and FABP4, APOE, and FASN (p < 0.01), and reduced levels of ATGL and HSL (p < 0.05). Luciferase reporter assays revealed that ACSL1 is a target of miR-218-5p, which can reduce the mRNA and protein levels of ACSL1 by directly binding the 3′ untranslated region of ACSL1. Furthermore, miR-218-5p has an inhibition role in porcine preadipocyte differentiation by suppressing ACSL1 expression. Taken together, these data provide insights into the mechanism of the miR-218-5p/ACSL1 axis in regulating subcutaneous fat deposition of pigs.

Role of Distinct Fat Depots in Metabolic Regulation and Pathological Implications

People suffering from obesity and associated metabolic disorders including diabetes are increasing exponentially around the world. Adipose tissue (AT) distribution and alteration in their biochemical properties play a major role in the pathogenesis of these diseases. Emerging evidence suggests that AT heterogeneity and depot-specific physiological changes are vital in the development of insulin resistance in peripheral tissues like muscle and liver. Classically, AT depots are classified into white adipose tissue (WAT) and brown adipose tissue (BAT); WAT is the site of fatty acid storage, while BAT is a dedicated organ of metabolic heat production. The discovery of beige adipocyte clusters in WAT depots indicates AT heterogeneity has a more central role than hither to ascribed. Therefore, we have discussed in detail the current state of understanding on cellular and molecular origin of different AT depots and their relevance toward physiological metabolic homeostasis. A major focus is to highlight the correlation between altered WAT distribution in the body and metabolic pathogenesis in animal models and humans. We have also underscored the disparity in the molecular (including signaling) changes in various WAT tissues during diabetic pathogenesis. Exercise-mediated beneficial alteration in WAT physiology/distribution that protects against metabolic disorders is evolving. Here we have discussed the depot-specific biochemical adjustments induced by different forms of exercise. A detailed understanding of the molecular details of inter-organ crosstalk via substrate utilization/storage and signaling through chemokines provide strategies to target selected WAT depots to pharmacologically mimic the benefits of exercise countering metabolic diseases including diabetes.

The ATF3 inducer protects against diet-induced obesity via suppressing adipocyte adipogenesis and promoting lipolysis and browning

In this study, we investigated whether the activating transcription factor 3 (ATF3) inducer ST32db, a synthetic compound with a chemical structure similar to that of native Danshen compounds, exerts an anti-obesity effect in 3T3-L1 white preadipocytes, D16 beige cells, and mice with obesity induced by a high-fat diet (HFD). The results showed that ST32db inhibited 3T3-L1 preadipocyte differentiation by inhibiting adipogenesis/lipogenesis-related gene (and protein levels) and enhancing lipolysis-related gene (and protein levels) via the activation of β3-adrenoceptor (β3-AR)/PKA/p38, AMPK, and ERK pathways. Furthermore, ST32db inhibited triacylglycerol accumulation in D16 adipocytes by suppressing adipogenesis/lipogenesis-related gene (and protein levels) and upregulating browning gene expression by suppressing the β3-AR/PKA/p38, and AMPK pathways. Intraperitoneally injected ST32db (1 mg kg-1 twice weekly) inhibited body weight gain and reduced the weight of inguinal white adipose tissue (iWAT), epididymal WAT (eWAT), and mesenteric WAT, with no effects on food intake by the obese mice. The adipocyte diameter and area of iWAT and eWAT were decreased in obese mice injected with ST32db compared with those administered only HFD. In addition, ST32db significantly suppressed adipogenesis and activated lipolysis, browning, mitochondrial oxidative phosphorylation, and β-oxidation-related pathways by suppressing the p38 pathway in the iWAT of the obese mice. These results indicated that the ATF3 inducer ST32db has therapeutic potential for reducing obesity.

MEK6 Overexpression Exacerbates Fat Accumulation and Inflammatory Cytokines in High-Fat Diet-Induced Obesity

Obesity is a state of abnormal fat accumulation caused by an energy imbalance potentially caused by changes in multiple factors. MEK6 engages in cell growth, such as inflammation and apoptosis, as one of the MAPK signaling pathways. The MEK6 gene was found to be related to RMR, a gene associated with obesity. Because only a few studies have investigated the correlation between MEK6 and obesity or the relevant mechanisms, we conducted an experiment using a TgMEK6 model with MEK6 overexpression with non-Tg and chow diet as the control to determine changes in lipid metabolism in plasma, liver, and adipose tissue after a 15-week high-fat diet (HFD). MEK6 overexpression in the TgMEK6 model significantly increased body weight and plasma triglyceride and total cholesterol levels. p38 activity declined in the liver and adipose tissues and lowered lipolysis, oxidation, and thermogenesis levels, contributing to decreased energy consumption. In the liver, lipid formation and accumulation increased, and in adipose, adipogenesis and hypertrophy increased. The adiponectin/leptin ratio significantly declined in plasma and adipose tissue of the TgMEK6 group following MEK6 expression and the HFD, indicating the role of MEK6 expression in adipokine regulation. Plasma and bone-marrow-derived macrophages (BMDM) of the TgMEK6 group increased MEK6 expression-dependent secretion of pro-inflammatory cytokines but decreased levels of anti-inflammatory cytokines, further exacerbating the results exhibited by the diet-induced obesity group. In conclusion, this study demonstrated the synergistic effect of MEK6 with HFD in fat accumulation by significantly inhibiting the mechanisms of lipolysis in the adipose and M2 associated cytokines secretion in the BMDM.

AMPK activation by SC4 inhibits noradrenaline-induced lipolysis and insulin-stimulated lipogenesis in white adipose tissue

The effects of small-molecule AMP-activated protein kinase (AMPK) activators in rat epididymal adipocytes were compared. SC4 was the most effective and submaximal doses of SC4 and 5-amino-4-imidazolecarboxamide (AICA) riboside were combined to study the effects of AMPK activation in white adipose tissue (WAT). Incubation of rat adipocytes with SC4 + AICA riboside inhibited noradrenaline-induced lipolysis and decreased hormone-sensitive lipase (HSL) Ser563 phosphorylation, without affecting HSL Ser565 phosphorylation. Preincubation of fat pads from wild-type (WT) mice with SC4 + AICA riboside inhibited insulin-stimulated lipogenesis from glucose or acetate and these effects were lost in AMPKα1 knockout (KO) mice, indicating AMPKα1 dependency. Moreover, in fat pads from acetyl-CoA carboxylase (ACC)1/2 S79A/S212A double knockin versus WT mice, the effect of SC4 + AICA riboside to inhibit insulin-stimulated lipogenesis from acetate was lost, pinpointing ACC as the main AMPK target. Treatment with SC4 + AICA riboside decreased insulin-stimulated glucose uptake, an effect that was still observed in fat pads from AMPKα1 KO versus WT mice, suggesting the effect was partly AMPKα1-independent. SC4 + AICA riboside treatment had no effect on the insulin-induced increase in palmitate esterification nor on sn-glycerol-3-phosphate-O-acyltransferase activity. Therefore in WAT, AMPK activation inhibits noradrenaline-induced lipolysis and suppresses insulin-stimulated lipogenesis primarily by inactivating ACC and by inhibiting glucose uptake.

p38γ and p38δ regulate postnatal cardiac metabolism through glycogen synthase 1

During the first weeks of postnatal heart development, cardiomyocytes undergo a major adaptive metabolic shift from glycolytic energy production to fatty acid oxidation. This metabolic change is contemporaneous to the up-regulation and activation of the p38γ and p38δ stress-activated protein kinases in the heart. We demonstrate that p38γ/δ contribute to the early postnatal cardiac metabolic switch through inhibitory phosphorylation of glycogen synthase 1 (GYS1) and glycogen metabolism inactivation. Premature induction of p38γ/δ activation in cardiomyocytes of newborn mice results in an early GYS1 phosphorylation and inhibition of cardiac glycogen production, triggering an early metabolic shift that induces a deficit in cardiomyocyte fuel supply, leading to whole-body metabolic deregulation and maladaptive cardiac pathogenesis. Notably, the adverse effects of forced premature cardiac p38γ/δ activation in neonate mice are prevented by maternal diet supplementation of fatty acids during pregnancy and lactation. These results suggest that diet interventions have a potential for treating human cardiac genetic diseases that affect heart metabolism.

The beta2 -adrenergic receptor - a re-emerging target to combat obesity and induce leanness?

Treatment of obesity with repurposed or novel drugs is an expanding research field. One approach is to target beta₂ -adrenergic receptors because they regulate the metabolism and phenotype of adipose and skeletal muscle tissue. Several observations support a role for the beta₂ -adrenergic receptor in obesity. Specific human beta₂ -adrenergic receptor polymorphisms are associated with body composition and obesity, for which the Gln27Glu polymorphism is associated with obesity, while the Arg16Gly polymorphism is associated with lean mass in men and the development of obesity in specific populations. Individuals with obesity also have lower abundance of beta₂ -adrenergic receptors in adipose tissue and are less sensitive to catecholamines. In addition, studies in livestock and rodents demonstrate that selective beta₂ -agonists induce a so-called 'repartitioning effect' characterized by muscle accretion and reduced fat deposition. In humans, beta₂ -agonists dose-dependently increase resting metabolic rate by 10-50%. And like that observed in other mammals, only a few weeks of treatment with beta₂ -agonists increases muscle mass and reduces fat mass in young healthy individuals. Beta₂ -agonists also exert beneficial effects on body composition when used concomitantly with training and act additively to increase muscle strength and mass during periods with resistance training. Thus, the beta₂ -adrenergic receptor seems like an attractive target in the development of anti-obesity drugs. However, future studies need to verify the long-term efficacy and safety of beta₂ -agonists in individuals with obesity, particularly in those with comorbidities.

Ketone bodies for the failing heart: fuels that can fix the engine?

Accumulating evidence suggests that the failing heart reverts energy metabolism toward increased utilization of ketone bodies. Despite many discrepancies in the literature, evidence from both bench and clinical research demonstrates beneficial effects of ketone bodies in heart failure. Ketone bodies are readily oxidized by cardiomyocytes and can provide ancillary fuel for the energy-starved failing heart. In addition, ketone bodies may help to restore cardiac function by mitigating inflammation, oxidative stress, and cardiac remodeling. In this review, we hypothesize that a therapeutic approach intended to restore cardiac metabolism through ketone bodies could both refuel and 'repair' the failing heart.

Selected metabolic, epigenetic, nitration and redox parameters in turkeys fed diets with different levels of arginine and methionine

The amino acid guidelines formulated by British United Turkeys postulate higher levels of lysine (Lys) in turkey diets than those recommended by the National Research Council. However, any modifications in the Lys content of turkey diets should be accompanied by changes in the inclusion rates of other amino acids, including methionine (Met) and arginine (Arg). The research hypothesis postulates that the appropriate inclusion levels and ratios of arginine and methionine in turkey diets with high lysine content can improve the antioxidant status of turkeys without compromising their metabolism. The aim of this study was to determine the influence of different Arg and Met ratios in Lys-rich diets on biochemical indicators, redox status and epigenetic changes in turkeys. The turkeys were assigned to six groups with eight replicates per group and 18 birds per replicate. Six feeding programs, with three dietary Arg levels (90%, 100% and 110%) and two dietary Met levels (30% and 45%) relative to dietary Lys content were compared. During each of the four feeding phases, birds were fed ad libitum isocaloric diets with high Lys content. Our results show, that in growing turkeys fed diets with high Lys content, the inclusion rate of Arg can be set at 90% of Lys content with no negative effects on their antioxidant status, metabolism or performance. Diets with high Arg content (110% Lys) are not recommended due to the risk of lipid and protein damage, and an undesirable increase in insulin and T4 levels. Regardless of dietary Arg levels, an increase in the Met inclusion rate from 30% to 45% of Lys content minimizes the oxidation of lipids, proteins and DNA, and increases the antioxidant defense potential of turkeys.

Methylglyoxal attenuates isoproterenol-induced increase in uncoupling protein 1 expression through activation of JNK signaling pathway in beige adipocytes

Methylglyoxal (MG) is a metabolite derived from glycolysis whose levels in the blood and tissues of patients with diabetes are higher than those of healthy individuals, suggesting that MG is associated with the development of diabetic complications. However, it remains unknown whether high levels of MG are a cause or consequence of diabetes. Here, we show that MG negatively affects the expression of uncoupling protein 1 (UCP1), which is involved in thermogenesis and the regulation of systemic metabolism. Decreased Ucp1 expression is associated with obesity and type 2 diabetes. We found that MG attenuated the increase in Ucp1 expression following treatment with isoproterenol in beige adipocytes. However, MG did not affect protein kinase A signaling, the core coordinator of isoproterenol-induced Ucp1 expression. Instead, MG activated c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases. We found that JNK inhibition, but not p38, recovered isoproterenol-stimulated Ucp1 expression under MG treatment. Altogether, these results suggest an inhibitory role of MG on the thermogenic function of beige adipocytes through the JNK signaling pathway.