5.1 µm Ion-Regulated Rigid Quasi-Solid Electrolyte Constructed by Bridging Fast Li-Ion Transfer Channels for Lithium Metal Batteries.

An ultra-thin quasi-solid electrolyte (QSE) with dendrite-inhibiting properties is a requirement for achieving high energy density quasi-solid lithium metal batteries (LMBs). Here, a 5.1 µm rigid QSE layer is directly designed on the cathode, in which Kevlar (poly(p-phenylene terephthalate)) nanofibers (KANFs) with negatively charged groups bridging metal-organic framework (MOF) particles are served as a rigid skeleton, and non-flammable deep eutectic solvent is selected to be encapsulated into the MOF channels, combined with in situ polymerization to complete safe electrolyte system with high rigidness and stability. The QSE with constructed topological network demonstrates high rigidity (5.4 GPa), high ionic conductivity (0.73 mS cm-1 at room temperature), good ion-regulated properties, and improved structural stability, contributing to homogenized Li-ion flux, excellent dendrite suppression, and prolonged cyclic performance for LMB. Additionally, ion regulation influences the Li deposition behavior, exhibiting a uniform morphology on the Li-metal surface after cycling. According to density-functional theory, KANFs bridging MOFs as hosts play a vital function in the free-state and fast diffusion dynamics of Li-ions. This work provides an effective strategy for constructing ultrathin robust electrolytes with a novel ionic conduction mode.

Association between the traditional Chinese medicine constitution and metabolic dysfunction-associated fatty liver disease in older people: A cross-sectional study.

Background: Few studies have focused on the relationship between the traditional Chinese medicine constitution (TCMC) and metabolic dysfunction-associated fatty liver disease (MAFLD) in older populations. We sought to investigate the distribution of MAFLD and the TCMC in older people, and provide a theoretical basis for TCMC-based management of MAFLD in this population. Methods: A cross-sectional study was conducted among older (≥65 years) individuals in Zhongshan, China. Information on common sociodemographic characteristics, medical history, anthropometric measurements, and the TCMC was collected. The chi-square test, multivariable logistic regression analysis, subgroup analysis, and inverse probability weighting of the propensity score were used to explore the relationship between MAFLD and the TCMC. Results: Of 7085 participants, 1408 (19.9 %) had MAFLD. The three most common TCMC types in MAFLD patients were "phlegm-dampness", "gentleness", and "yin-deficiency". After adjustment for gender, age, tobacco smoking, alcohol consumption, body mass index, abnormal waist-to-hip ratio, hypertension, diabetes mellitus, and dyslipidemia, MAFLD was positively associated with the phlegm-dampness constitution (PDC) (ORadjusted (95 % CI) = 1.776 (1.496-2.108), P < 0.001), and negatively correlated with the qi-depression constitution (0.643 (0.481-0.860), 0.003). A stronger correlation between the PDC and MAFLD was observed in men compared with women (ORadjusted = 2.04 (95%CI = 1.47-2.84) vs. 1.70 (95%CI = 1.39-2.08), Pinteraction = 0.003) as well as between people who smoked tobacco and non-tobacco-smoking individuals (2.11 (1.39-3.21) vs. 1.75 (1.45-2.12), 0.006). Conclusions: A positive relationship was observed between MAFLD and the PDC in older people living in Zhongshan. Early detection and treatment of the PDC (especially in men and smokers) could prevent the occurrence and development of MAFLD.

The effect of pulcherriminic acid produced by Metschnikowia citriensis in controlling postharvest diseases of citrus fruits.

The biocontrol effectiveness of Metschnikowia citriensis relies on its production of pulcherriminic acid (PA), which forms insoluble and stable pulcherrimin pigments by chelating iron ions, this inhibits pathogen growth by preventing their utilization of chelated Fe3+. In this study, ΔM. citriensis, which did not produce PA, was used as a control to examine changes in its biocontrol effectiveness by adding tryptophan to the medium. Tryptophan was shown to have no discernible impact on the growth and PA production of ΔM. citriensis; moreover, the PA synthesis-related genes PULs, Snf2, and leucyl-tRNA synthesis-related genes A3136 and A3022 were all down-regulated in ΔM. citriensis. The PA-free ΔM. citriensis eventually showed a much poorer inhibition zone against the pathogens in vitro, and a noticeably decreased control efficiency against postharvest diseases in citrus fruit. Tryptophan was added to the medium, which had no appreciable impact on inhibitory zone of ΔM. citriensis against pathogens in vitro, but enhanced its ability to control citrus postharvest diseases. Additionally, the control effects of culture broth of M. citriensis and ΔM. citriensis on postharvest diseases in citrus fruit were assessed. It was found that both culture broth of M. citriensis and ΔM. citriensis exhibited remarkable control effects against citrus postharvest diseases, with culture broth of M. citriensis which containing PA being more effective in controlling the disease. Last but not least, we extracted and dissolved pulcherrimin to obtain PA extracts, which were then injected to citrus fruits to assess the biocontrol effectiveness. The findings demonstrated that postharvest diseases of citrus fruit can be effectively controlled by PA extracts. This research suggested a new biological strategy for the management of citrus postharvest diseases.

The mediation and interaction of the obesity index between moderate-vigorous recreational physical activity and hypertension.

Previous studies showed that physical activity (PA) is concerned with hypertension (HTN). However, the mediation and interaction role of the obesity index: body mass index (BMI), waist-hip ratio (WHR), body fat rate (BFR) and visceral fat index (VFI) between PA and HTN has never been studied. Therefore, the purpose of this study was to assess the mediation and interaction of the obesity index between moderate-vigorous recreational physical activity (MVRPA) and HTN. We conducted a cross-sectional study of 4710 individuals aged 41 or older in Torch Development Zone, Zhongshan City. The mediation and interaction of the obesity index were evaluated by a four-way decomposition. 48.07% of participants had HTN among these groups. In the adjusted linear regression model, MVRPA was significantly correlated with WHR (ß±SE = -0.005±0.002; P<0.05). Compared to sufficient MVRPA (odds ratio (OR) = 1.35), 95% (confidence interval (CI) = 1.17-1.56), insufficient MVRPA increased the risk of developing HTN. Furthermore, there were associations between BMI, WHR, BFR, VFI and HTN where the adjusted ORs and 95% CIs were 1.11 (1.09-1.13), 6.23 (2.61-14.90), 1.04 (1.03-1.06), 1.07 (1.06-1.09), respectively. The mediation analyses suggested that the impact of MVRPA on HTN risk may partly be explained by changes in obesity index, with a pure indirect mediation of WHR between MVRPA and HTN (P<0.05). Therefore, weight control, especially reducing abdominal obesity and maintaining adequate MVRPA, may lead to more proper control of HTN.

Correlation analysis of anthropometric indices and type 2 diabetes mellitus in residents aged 60 years and older.

Background and purpose: In recent years, the incidence of obesity in people aged 60 and over has increased significantly, and abdominal obesity has been recognized as an independent risk factor for diabetes. Aging causes physiologic decline in multiple body systems, leading to changes in obesity indicators such as BMI. At present, the relationship between abdominal obesity markers and Diabetes mellitus (DM) in people aged 60 years and older remains unclear. Therefore, it is necessary to study the correlation between anthropometric indices and diabetes and explore potential predictors. Methods: The basic demographic information of participants aged 60 and above in Zhongshan City in 2020 was collected. Physical parameters, blood glucose and other biochemical indices were measured comprehensively. Binary logistic regression analysis was used to explore the relationship between abdominal obesity indicators [Waist circumference, Neck Circumference, Waist-to-hip ratio, Chinese Visceral Obesity Index (CVAI), and visceral obesity index] and diabetes mellitus. ROC characteristic curve was used to analyze the predictive ability of abdominal obesity indicators to DM, and the non-restrictive cubic spline graph was used to visualize the screened obesity indicators and diabetes risk. Results: Among 9,519 participants, the prevalence of diabetes was 15.5%. Compared with low CVAI, High CVAI level was significantly associated with increased prevalence of DM in males and females (all p < 0.05), in males (OR, 2.226; 95%CI: 1.128-4.395), females (OR, 1.645; 95%CI: 1.013-2.669). After adjusting for potential confounding factors, there were gender differences between neck circumference and the prevalence of DM, and above-normal neck circumference in males was significantly associated with increased prevalence of DM (OR, 1.381; 95% CI: 1.091-1.747) (p < 0.05). Conclusion: Among these anthropometric indices, CVAI is consistent with the features of fat distribution in older individuals and shows superior discriminative power as a potential predictor of DM, compared to traditional anthropometric parameters.

The multiple facets of acetyl-CoA metabolism: Energetics, biosynthesis, regulation, acylation and inborn errors.

Acetyl-coenzyme A (Ac-CoA) is a core metabolite with essential roles throughout cell physiology. These functions can be classified into energetics, biosynthesis, regulation and acetylation of large and small molecules. Ac-CoA is essential for oxidative metabolism of glucose, fatty acids, most amino acids, ethanol, and of free acetate generated by endogenous metabolism or by gut bacteria. Ac-CoA cannot cross lipid bilayers, but acetyl groups from Ac-CoA can shuttle across membranes as part of carrier molecules like citrate or acetylcarnitine, or as free acetate or ketone bodies. Ac-CoA is the basic unit of lipid biosynthesis, providing essentially all of the carbon for the synthesis of fatty acids and of isoprenoid-derived compounds including cholesterol, coenzyme Q and dolichols. High levels of Ac-CoA in hepatocytes stimulate lipid biosynthesis, ketone body production and the diversion of pyruvate metabolism towards gluconeogenesis and away from oxidation; low levels exert opposite effects. Acetylation changes the properties of molecules. Acetylation is necessary for the synthesis of acetylcholine, acetylglutamate, acetylaspartate and N-acetyl amino sugars, and to metabolize/eliminate some xenobiotics. Acetylation is a major post-translational modification of proteins. Different types of protein acetylation occur. The most-studied form occurs at the epsilon nitrogen of lysine residues. In histones, lysine acetylation can alter gene transcription. Acetylation of other proteins has diverse, often incompletely-documented effects. Inborn errors related to Ac-CoA feature a broad spectrum of metabolic, neurological and other features. To date, a small number of studies of animals with inborn errors of CoA thioesters has included direct measurement of acyl-CoAs. These studies have shown that low levels of tissue Ac-CoA correlate with the development of clinical signs, hinting that shortage of Ac-CoA may be a recurrent theme in these conditions. Low levels of Ac-CoA could potentially disrupt any of its roles.

Tryptophan enhances biocontrol efficacy of Metschnikowia citriensis FL01 against postharvest fungal diseases of citrus fruit by increasing pulcherriminic acid production.

The aim of this work was to study the capability and mechanism of enhancing the yield of pulcherriminic acid (PA) produced by Metschnikowia citriensis FL01 with the help of tryptophan for the control of postharvest diseases on citrus caused by Penicillium italicum, Geotrichum citri-aurantii and Penicillium digitatum. The adding of 10 mmol/L tryptophan to the growth medium resulted in the widest pulcherrimin pigment zone produced by M. citriensis FL01. The adding of tryptophan to the growth medium upregulated A3136 and A3022 gene expression (responsible for leucyl-tRNA biosynthesis from leucine), downregulated A1350 gene expression (responsible for the biosynthesis of leucine to branched-chain fatty acids), and decreased the content of intracellular leucine in M. citriensis FL01, speculating that the addition of tryptophan in the growth medium induced leucine conversion toward leucyl-tRNA in M. citriensis FL01. Moreover, the adding of tryptophan to the growth medium upregulated PULs (responsible PA biosynthesis) and Snf2 (transcriptional regulator) gene expression and promoted intracellular, extracellular or total PA production by M. citriensis FL01 in liquid medium. In addition, the addition of tryptophan in the growth medium showed no effect on the growth of M. citriensis FL01 itself in liquid medium, while the population dynamics in citrus fruit wounds of M. citriensis FL01 with the addition of tryptophan in the growth medium were increased compared with those of M. citriensis FL01. What's more, M. citriensis FL01 with the addition of tryptophan in the growth medium completely inhibited the growth of pathogens in vitro. The disease incidences and lesion diameters of blue mold, sour rot and green mold on citrus fruit were lower in group which treated with M. citriensis FL01 containing tryptophan in the growth medium than that treated with M. citriensis FL01 alone. Overall, the postharvest biocontrol of citrus with M. citriensis FL01 containing 10 mmol/L tryptophan in the growth medium is a promising approach to protect these fruits from blue mold, sour rot and green mold.

Iron Competition as an Important Mechanism of Pulcherrimin-Producing Metschnikowia sp. Strains for Controlling Postharvest Fungal Decays on Citrus Fruit.

This study identified and tested fruit-isolated Metschnikowia yeasts against three major postharvest citrus pathogens, namely, Penicillium digitatum, Penicillium italicum, and Geotrichum citri-aurantii, and further evaluated the impact of FeCl3 on the biocontrol efficiency of pulcherrimin-producing M. pulcherrima strains. Based on the characterization of the pigmented halo surrounding the colonies and the analysis of the D1/D2 domain of 26S rDNA, a total of 46 Metschnikowia sp. were screened and identified. All 46 Metschnikowia strains significantly inhibited the hyphal growth of Penicillium digitatum, Penicillium italicum, and Geotrichum citri-aurantii, and effectively controlled the development of green mold, blue mold and sour rot of citrus fruit. The introduction of exogenous FeCl3 at certain concentrations did not significantly impact the pulcherriminic acid (PA) production of pigmented M. pulcherrima strains, but notably diminished the size of pigmented zones and the biocontrol efficacy against the three pathogens. Iron deficiency sensitivity experiments revealed that P. digitatum and P. italicum exhibited higher sensitivity compared to G. citri-aurantii, indicating that iron dependence varied among the three pathogens. These results suggested that M. pulcherrima strains, capable of producing high yields of PA, possessed great potential for use as biocontrol agents against postharvest citrus diseases. The biocontrol efficacy of these yeasts is mainly attributed to their ability to competitively deplete iron ions in a shared environment, with the magnitude of their pigmented halo directly correlating to their antagonistic capability. It is worth noting that the level of sensitivity of pathogens to iron deficiency might also affect the biocontrol effect of pulcherrimin-producing M. pulcherrima.

Cardiac-specific deficiency of 3-hydroxy-3-methylglutaryl coenzyme A lyase in mice causes cardiomyopathy and a distinct pattern of acyl-coenzyme A-related biomarkers.

Deficiency of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) lyase (HL) is an autosomal recessive inborn error of acyl-CoA metabolism affecting the last step of leucine degradation. Patients with HL deficiency (HLD) can develop a potentially fatal cardiomyopathy. We created mice with cardiomyocyte-specific HLD (HLHKO mice), inducing Cre recombinase-mediated deletion of exon 2 at two months of age. HLHKO mice survive, but develop left ventricular hypertrophy by 9 months. Also, within minutes after intraperitoneal injection of the leucine metabolite 2-ketoisocaproate (KIC), they show transient left ventricular hypocontractility and dilation. Leucine-related acyl-CoAs were elevated in HLHKO heart (e.g., HMG-CoA, 34.0 ± 4.4 nmol/g versus 0.211 ± 0.041 in controls, p < 0.001; 3-methylcrotonyl-CoA, 5.84 ± 0.69 nmol/g versus 0.282 ± 0.043, p < 0.001; isovaleryl-CoA, 1.86 ± 0.30 nmol/g versus 0.024 ± 0.014, p < 0.01), a similar pattern to that in liver of mice with hepatic HL deficiency. After KIC loading, HMG-CoA levels in HLHKO heart were higher than under basal conditions, as were the ratios of HMG-CoA/acetyl-CoA and of HMG-CoA/succinyl-CoA. In contrast to the high levels of multiple leucine-related acyl-CoAs, biomarkers in urine and plasma of HLHKO mice show isolated hyper-3-methylglutaconic aciduria (700.8 ± 48.4 mmol/mol creatinine versus 37.6 ± 2.4 in controls, p < 0.001), and elevated C5-hydroxyacylcarnitine in plasma (0.248 ± 0.014 µmol/L versus 0.048 ± 0.005 in controls, p < 0.001). Mice with liver-specific HLD were compared, and showed normal echocardiographic findings and normal acyl-CoA profiles in heart. This study of nonhepatic tissue-specific HLD outside of liver reveals organ-specific origins of diagnostic biomarkers for HLD in blood and urine and shows that mouse cardiac HL is essential for myocardial function in a cell-autonomous, organ-autonomous fashion.

Influence of arginine on the biocontrol efficiency of Metschnikowia citriensis against Geotrichum citri-aurantii causing sour rot of postharvest citrus fruit.

This study investigated the effect of arginine (Arg) on the antagonistic activity of Metschnikowia citriensis against sour rot caused by Geotrichum citri-aurantii in postharvest citrus, and evaluated the possible mechanism therein. Arg treatment up-regulated the PUL genes expression, and significantly induced the pulcherriminic acid (PA) production of M. citriensis, which related to the capability of iron depletion of M. citriensis. By comparing the biocontrol effects of Arg-treated and untreated yeast cells, it was found that Arg treatment significantly enhanced the biocontrol efficacy of M. citriensis, and 5 mmol L-1 Arg exerted the best effect. Additionally, the biofilm formation ability of M. citriensis was greatly enhanced by Arg, and the higher population density of yeast cells in citrus wounds was also observed in Arg treatment groups stored both at 25 °C and 4 °C. Moreover, Arg was shown to function as a cell protectant to elevate antioxidant enzyme activity [including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX)] and intracellular trehalose content to resist oxidative stress damage, that directly helped to enhance colonization ability of yeasts in fruit wounds. These results suggest the application of Arg is a useful approach to improve the biocontrol performance of M. citriensis.

Propionic acidemia in mice: Liver acyl-CoA levels and clinical course.

Propionic acidemia (PA) is a severe autosomal recessive metabolic disease caused by deficiency of propionyl-CoA carboxylase (PCC). We studied PA transgenic (Pat) mice that lack endogenous PCC but express a hypoactive human PCCA cDNA, permitting their survival. Pat cohorts followed from 3 to 20 weeks of age showed growth failure and lethal crises of lethargy and hyperammonemia, commoner in males (27/50, 54%) than in females (11/52, 21%) and occurring mainly in Pat mice with the most severe growth deficiency. Groups of Pat mice were studied under basal conditions (P-Ba mice) and during acute crises (P-Ac). Plasma acylcarnitines in P-Ba mice, compared to controls, showed markedly elevated C3- and low C2-carnitine, with a further decrease in C2-carnitine in P-Ac mice. These clinical and biochemical findings resemble those of human PA patients. Liver acyl-CoA measurements showed that propionyl-CoA was a minor species in controls (propionyl-CoA/acetyl-CoA ratio, 0.09). In contrast, in P-Ba liver the ratio was 1.4 and in P-Ac liver, 13, with concurrent reductions of the levels of acetyl-CoA and other acyl-CoAs. Plasma ammonia levels in control, P-Ba and P-Ac mice were 109 ± 10, 311 ± 48 and 551 ± 61 µmol/L respectively. Four-week administration to Pat mice, of carglumate (N-carbamyl-L-glutamic acid), an analogue of N-carbamylglutamate, the product of the only acyl-CoA-requiring reaction directly related to the urea cycle, was associated with increased food consumption, improved growth and absence of fatal crises. Pat mice showed many similarities to human PA patients and provide a useful model for studying tissue pathophysiology and treatment outcomes.

Metschnikowia citriensis FL01 antagonize Geotrichum citri-aurantii in citrus fruit through key action of iron depletion.

Metschnikowia citriensis FL01 has great potential for biocontrol applications for its excellent biocontrol efficacy on postharvest diseases of citrus fruit, and the iron depletion by pulcherriminic acid (PA) and then formation of insoluble pigment pulcherrimin had been speculated as an important action mechanism. To identify the genes involved in pulcherrimin synthesis and reutilization in M. citriensis FL01, we de novo assembled the genome of M. citriensis FL01 based on long-read PacBio sequencing. The final assembled genome consisted of 12 contigs with a genome size of 25.74 Mb, G + C content of 49.16% and 9310 protein-coding genes. The genome-wide BLAST of the PUL genes of M. pulcherrima APC 1.2 showed that the four PUL genes were clustered and located on Contig 4 of M. citriensis FL01. In order to further clarify the role of pulcherrimin pigment on biocontrol of M. citriensis FL01, CRISPR/cas9 technology was used to knock out PUL2 gene that was responsible for PA synthesis and the pigmentless mutants with stable phenotype were obtained. The mutant strains of M. citriensis FL01 lost the ability to produce pulcherrimin pigment, and simultaneously lost the ability to inhibit the growth of Geotrichum citri-aurantii in vitro. Moreover, the biocontrol efficacy of pigmentless mutant strains against sour rot was about 80% lower than that of wild-type M. citriensis FL01. These results directly proved that the iron depletion was an important mechanism of M. citriensis FL01.

Biocontrol ability and action mechanism of Metschnikowia citriensis against Geotrichum citri-aurantii causing sour rot of postharvest citrus fruit.

This study investigated the biocontrol efficiency of Metschnikowia citriensis strain FL01 against Geotrichum citri-aurantii, and evaluated possible mechanisms. The results showed that M. citriensis could effectively control the development of sour rot, and significantly inhibit the mycelial growth and spore germination of G. citri-aurantii. The population dynamics results and Scanning electron microscopy (SEM) analysis indicated that M. citriensis could rapidly colonize wounds and tightly adhere to the surface of the wounds to compete with G. citri-aurantii for nutrition and space. M. citriensis also showed the biofilm formation action in vitro. The response of G. citri-aurantii to different components of M. citriensis culture showed that only the yeast cells but not the extracellular metabolites and the volatile organic compounds (VOCs) exhibited inhibitory effect on the growth of G. citri-aurantii. M. citriensis adhered to the hyphae of G. citri-aurantii loosely and sparsely, and the production of lytic enzymes ß-1, 3-glucanase (GLU) and Chitinase (CHI) could not be induced by G. citri-auranti. Iron affected the pulcherrimin pigment production and antagonism of M. citriensis indicating iron depletion as the most important antagonistic mechanism. Besides, M. citriensis also induced resistance of fruit against sour rot. These results suggested that M. citriensis could be used as the potential alternative of fungicides to control postharvest pathogens on citrus fruit.

PPARγ coactivator-1α (PGC-1α) protects neuroblastoma cells against amyloid-beta (Aß) induced cell death and neuroinflammation via NF-κB pathway.

BACKGROUND: Alzheimer's disease is characterized by the accumulation of amyloid beta (Aß) and the formation of neurofibrillary tangles. Aß is the main constituent of senile plaques and is largely involved in neuronal death and neuroinflammation. Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is one of the main transcriptional coactivator and has been related to many fields such as energy metabolism, cardiovascular disease, neurodegenerative disorders, and so on. RESULTS: Treatment with Aß1-42 reduced the expression of PGC-1α in both protein and RNA levels of neuroblastoma N2a cells. Aß1-42 induced a robust activation of cleaved caspase-3 while PGC-1α suppressed this activation and protected N2a cells from Aß-induced cell death. Overexpression of PGC-1α significantly reduced the level of main proinflammatory cytokines. In addition, PGC-1α inhibited the transportation of NF-κB p65 from cytoplasm to nucleus and IκBα degradation induced by Aß1-42. CONCLUSION: Our results have demonstrated that PGC-1α can protect neuroblastoma cells against Aß-induced neuronal death and neuroinflammation. Moreover, this neuroprotective effect of PGC-1α is regulated through NF-κB pathway. Taken together, our work provides evidence that PGC-1α could be beneficial in targeting Aß neurotoxicity.

A beta cell ATGL-lipolysis/adipose tissue axis controls energy homeostasis and body weight via insulin secretion in mice.

AIMS/HYPOTHESIS: To directly assess the role of beta cell lipolysis in insulin secretion and whole-body energy homeostasis, inducible beta cell-specific adipose triglyceride lipase (ATGL)-deficient (B-Atgl-KO) mice were studied under normal diet (ND) and high-fat diet (HFD) conditions. METHODS: Atgl flox/flox mice were cross-bred with Mip-Cre-ERT mice to generate Mip-Cre-ERT/+;Atgl flox/flox mice. At 8 weeks of age, these mice were injected with tamoxifen to induce deletion of beta cell-specific Atgl (also known as Pnpla2), and the mice were fed an ND or HFD. RESULTS: ND-fed male B-Atgl-KO mice showed decreased insulinaemia and glucose-induced insulin secretion (GSIS) in vivo. Changes in GSIS correlated with the islet content of long-chain saturated monoacylglycerol (MAG) species that have been proposed to be metabolic coupling factors for insulin secretion. Exogenous MAGs restored GSIS in B-Atgl-KO islets. B-Atgl-KO male mice fed an HFD showed reduced insulinaemia, glycaemia in the fasted and fed states and after glucose challenge, as well as enhanced insulin sensitivity. Moreover, decreased insulinaemia in B-Atgl-KO mice was associated with increased energy expenditure, and lipid metabolism in brown (BAT) and white (WAT) adipose tissues, leading to reduced fat mass and body weight. CONCLUSIONS/INTERPRETATION: ATGL in beta cells regulates insulin secretion via the production of signalling MAGs. Decreased insulinaemia due to lowered GSIS protects B-Atgl-KO mice from diet-induced obesity, improves insulin sensitivity, increases lipid mobilisation from WAT and causes BAT activation. The results support the concept that fuel excess can drive obesity and diabetes via hyperinsulinaemia, and that an islet beta cell ATGL-lipolysis/adipose tissue axis controls energy homeostasis and body weight via insulin secretion.

The stoichiometry of protein phosphorylation in adipocyte lipid droplets: analysis by N-terminal isotope tagging and enzymatic dephosphorylation.

Most phosphoproteomic studies to date have been limited to the identification of phosphoproteins and their phosphorylation sites, and have not assessed the stoichiometry of protein phosphorylation, a critical parameter reflecting the dynamic equilibrium between phosphorylated and non-phosphorylated pools of proteins. Here, we used a method for measuring phosphorylation stoichiometry through isotope tagging and enzymatic dephosphorylation of tryptic peptides. Using this method, protein digests are divided into two equal aliquots that are modified with either light or heavy isotope tags. One aliquot is dephosphorylated by alkaline phosphatase. Finally, the peptide mixtures are recombined and LC-MS/MS analysis is performed. With this method, we studied adipocytes of mice stimulated with CL316,243, a beta-3 adrenergic agonist known to induce lipolysis and marked phosphorylation changes in proteins of the lipid droplet surface. In lipid droplet preparations, CL316,243 administration increased phosphorylation of proteins related to regulation of signaling, metabolism and intracellular trafficking in white adipose tissue, including hormone-sensitive lipase which was 80% phosphorylated at the previously reported site, Ser-559, and the lipid surface protein perilipin, which was phosphorylated by approximately 60 and approximately 40% at previously unreported sites, Ser-410 and Ser-460.

Lipolysis and the integrated physiology of lipid energy metabolism.

Fat cell lipolysis, the cleavage of triglycerides and release of fatty acids and glycerol, evolved to enable survival during prolonged food deprivation but is paradoxically increased in obesity, in which a surfeit of all energy metabolites is found. Essential, previously-unsuspected components have been discovered in the lipolytic machinery, at the protective interface of the lipid droplet surface and in the signaling pathways that control lipolysis. At least two adipocyte lipases are important for controlling lipolysis, hormone-sensitive lipase (HSL) and adipocyte triglyceride lipase (ATGL). Perilipin (PLIN) and possibly other proteins of the lipid droplet surface are master regulators of lipolysis, protecting or exposing the triglyceride core of the droplet to lipases. The prototypes for hormonal lipolytic control are beta adrenergic stimulation and suppression by insulin, both of which affect cyclic AMP levels and hence the protein kinase A-mediated phosphorylation of HSL and PLIN. Newly-recognized mediators of lipolysis include atrial natriuretic peptide, cyclic GMP, the ketone body 3-hydroxybutyrate, AMP kinase and mitogen-activated kinases. Lipolysis must be interpreted in its physiological context since similar rates of basal or stimulated lipolysis occur under different conditions and by different mechanisms. Age, sex, anatomical site, genotype and species differences are each important variables. Manipulation of lipolysis has therapeutic potential in several inborn errors and in the metabolic syndrome that frequently complicates obesity.

Adipocyte death defines macrophage localization and function in adipose tissue of obese mice and humans.

Macrophage infiltration of white adipose tissue (WAT) is implicated in the metabolic complications of obesity. The precipitating event(s) and function(s) of macrophage infiltration into WAT are unknown. We demonstrate that >90% of all macrophages in WAT of obese mice and humans are localized to dead adipocytes, where they fuse to form syncytia that sequester and scavenge the residual "free" adipocyte lipid droplet and ultimately form multinucleate giant cells, a hallmark of chronic inflammation. Adipocyte death increases in obese (db/db) mice (30-fold) and humans and exhibits ultrastructural features of necrosis (but not apoptosis). These observations identify necrotic-like adipocyte death as a pathologic hallmark of obesity and suggest that scavenging of adipocyte debris is an important function of WAT macrophages in obese individuals. The frequency of adipocyte death is positively correlated with increased adipocyte size in obese mice and humans and in hormone-sensitive lipase-deficient (HSL-/-) mice, a model of adipocyte hypertrophy without increased adipose mass. WAT of HSL-/- mice exhibited a 15-fold increase in necrotic-like adipocyte death and formation of macrophage syncytia, coincident with increased tumor necrosis factor-alpha gene expression. These results provide a novel framework for understanding macrophage recruitment, function, and persistence in WAT of obese individuals.

Hormone-sensitive lipase knockout mice have increased hepatic insulin sensitivity and are protected from short-term diet-induced insulin resistance in skeletal muscle and heart.

Insulin resistance in skeletal muscle and heart plays a major role in the development of type 2 diabetes and diabetic heart failure and may be causally associated with altered lipid metabolism. Hormone-sensitive lipase (HSL) is a rate-determining enzyme in the hydrolysis of triglyceride in adipocytes, and HSL-deficient mice have reduced circulating fatty acids and are resistant to diet-induced obesity. To determine the metabolic role of HSL, we examined the changes in tissue-specific insulin action and glucose metabolism in vivo during hyperinsulinemic euglycemic clamps after 3 wk of high-fat or normal chow diet in awake, HSL-deficient (HSL-KO) mice. On normal diet, HSL-KO mice showed a twofold increase in hepatic insulin action but a 40% decrease in insulin-stimulated cardiac glucose uptake compared with wild-type littermates. High-fat feeding caused a similar increase in whole body fat mass in both groups of mice. Insulin-stimulated glucose uptake was reduced by 50-80% in skeletal muscle and heart of wild-type mice after high-fat feeding. In contrast, HSL-KO mice were protected from diet-induced insulin resistance in skeletal muscle and heart, and these effects were associated with reduced intramuscular triglyceride and fatty acyl-CoA levels in the fat-fed HSL-KO mice. Overall, these findings demonstrate the important role of HSL on skeletal muscle, heart, and liver glucose metabolism.