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Analytical Chemistry Jun 2024Dual-organelle molecular localizers represent powerful new tools allowing the exploration of interorganelle physical contacts and subcellular chemical communication....
Dual-organelle molecular localizers represent powerful new tools allowing the exploration of interorganelle physical contacts and subcellular chemical communication. Here, we describe new dynamic molecular probes to localize mitochondria and lipid droplets taking advantage of the differential proton gradients present in these organelles as well as the activity of mitochondrial esterase. We unveil their potential utility when organelle retention mechanisms and proton gradients are synchronized, an insight that has not been documented previously. Our discoveries indicate that dual-organelle probes serve as a valuable multiplexing assay during starvation-induced autophagy. The pioneering molecular mechanism they employ opens doors to avoid using labile esters such as acetoxymethyl derivatives which are not optimal in imaging microscopy assays.
Topics: Lipid Droplets; Mitochondria; Fluorescent Dyes; Humans; Protons; HeLa Cells; Autophagy
PubMed: 38760019
DOI: 10.1021/acs.analchem.4c01703 -
Poultry Science Jul 2024Previously, we reported that glucagon-like peptide-1 (GLP-1) and its analog liraglutide could inhibit fat de novo synthesis in the liver and reduce abdominal fat...
Previously, we reported that glucagon-like peptide-1 (GLP-1) and its analog liraglutide could inhibit fat de novo synthesis in the liver and reduce abdominal fat accumulation in broiler chickens. Nevertheless, the impact of GLP-1 on adipocyte fat deposition remains enigmatic. This study aimed to investigate the effects of GLP-1, via its analog liraglutide, on chicken chicken adipocytes in vitro. Chemical assays, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot were employed to assess the proliferation, differentiation, and fat deposition of chicken adipocytes. Our findings indicated that liraglutide significantly suppressed cell proliferation and promoted preadipocyte differentiation in comparison to the control group. This was evidenced by elevated triglyceride (TG) content and upregulated mRNA expression of lipogenesis-related enzymes, such as acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), as well as regulators including peroxisome proliferator-activated receptor γ (PPARγ), sterol regulatory element binding protein-1 (SREBP1) and CCAAT/enhancer binding protein α (CEBPα). In mature adipocytes, liraglutide attenuated fat deposition by inhibiting fat de novo synthesis, evidenced by decreased mRNA expression of ACC, FAS, PPARγ, C/EBPα, and SREBP1, and concurrent upregulation of phosphorylated AMP-activated protein kinase (p-AMPK) and phosphorylated ACC (p-ACC). This resulted in reduced accumulation of lipid droplets and TG content in mature adipocytes. Collectively, our findings indicate that liraglutide suppresses the proliferation of preadipocytes, enhances their differentiation, and concurrently inhibits de novo lipogenesis in mature adipocytes. This observation offers profound insights into the mechanisms that underlie liraglutide's anti-adipogenic effects, which could have significant implications for the treatment of obesity in broiler chickens.
Topics: Animals; Liraglutide; Chickens; Adipocytes; Glucagon-Like Peptide 1; Lipogenesis; Adipogenesis; Cell Differentiation; Cell Proliferation; Adipose Tissue
PubMed: 38759567
DOI: 10.1016/j.psj.2024.103766 -
CNS Neuroscience & Therapeutics May 2024Sepsis-associated encephalopathy (SAE) is manifested as a spectrum of disturbed cerebral function ranging from mild delirium to coma. However, the pathogenesis of SAE...
AIMS
Sepsis-associated encephalopathy (SAE) is manifested as a spectrum of disturbed cerebral function ranging from mild delirium to coma. However, the pathogenesis of SAE has not been clearly elucidated. Astrocytes play important roles in maintaining the function and metabolism of the brain. Most recently, it has been demonstrated that disorders of lipid metabolism, especially lipid droplets (LDs) dyshomeostasis, are involved in a variety of neurodegenerative diseases. The aim of this study was to investigate whether LDs are involved in the underlying mechanism of SAE.
METHODS
The open field test, Y-maze test, and contextual fear conditioning test (CFCT) were used to test cognitive function in SAE mice. Lipidomics was utilized to investigate alterations in hippocampal lipid metabolism in SAE mice. Western blotting and immunofluorescence labeling were applied for the observation of related proteins.
RESULTS
In the current study, we found that SAE mice showed severe cognitive dysfunction, including spatial working and contextual memory. Meanwhile, we demonstrated that lipid metabolism was widely dysregulated in the hippocampus by using lipidomic analysis. Furthermore, western blotting and immunofluorescence confirmed that LDs accumulation in hippocampal astrocytes was involved in the pathological process of cognitive dysfunction in SAE mice. We verified that LDs can be inhibited by specifically suppress hypoxia-inducible lipid droplet-associated protein (HILPDA) in astrocytes. Meanwhile, cognitive dysfunction in SAE was ameliorated by reducing A1 astrocyte activation and inhibiting presynaptic membrane transmitter release.
CONCLUSION
The accumulation of astrocytic lipid droplets plays a crucial role in the pathological process of SAE. HILPDA is an attractive therapeutic target for lipid metabolism regulation and cognitive improvement in septic patients.
Topics: Animals; Lipid Droplets; Sepsis-Associated Encephalopathy; Astrocytes; Cognitive Dysfunction; Mice; Male; Mice, Inbred C57BL; Hippocampus; Lipid Metabolism; Maze Learning
PubMed: 38757390
DOI: 10.1111/cns.14758 -
Clinical Nutrition (Edinburgh, Scotland) Jun 2024Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disorder, characterized by the accumulation of excess fat in the liver, and is a driving factor for...
BACKGROUND & AIMS
Non-alcoholic fatty liver disease (NAFLD) is a common metabolic disorder, characterized by the accumulation of excess fat in the liver, and is a driving factor for various severe liver diseases. These multi-factorial and multi-timescale changes are observed in different clinical studies, but these studies have not been integrated into a unified framework. In this study, we aim to present such a unified framework in the form of a dynamic mathematical model.
METHODS
For model training and validation, we collected data for dietary or drug-induced interventions aimed at reducing or increasing liver fat. The model was formulated using ordinary differential equations (ODEs) and the mathematical analysis, model simulation, model formulation and the model parameter estimation were all performed in MATLAB.
RESULTS
Our mathematical model describes accumulation of fat in the liver and predicts changes in lipid fluxes induced by both dietary and drug interventions. The model is validated using data from a wide range of drug and dietary intervention studies and can predict both short-term (days) and long-term (weeks) changes in liver fat. Importantly, the model computes the contribution of each individual lipid flux to the total liver fat dynamics. Furthermore, the model can be combined with an established bodyweight model, to simulate even longer scenarios (years), also including the effects of insulin resistance and body weight. To help prepare for corresponding eHealth applications, we also present a way to visualize the simulated changes, using dynamically changing lipid droplets, seen in images of liver biopsies.
CONCLUSION
In conclusion, we believe that the minimal model presented herein might be a useful tool for future applications, and to further integrate and understand data regarding changes in dietary and drug induced changes in ectopic TAG in the liver. With further development and validation, the minimal model could be used as a disease progression model for steatosis.
Topics: Humans; Non-alcoholic Fatty Liver Disease; Liver; Models, Theoretical; Diet; Models, Biological; Lipid Metabolism
PubMed: 38754305
DOI: 10.1016/j.clnu.2024.05.017 -
Cell Reports Methods May 2024We present methods for making and testing the membrane biophysics of model lipid droplets (LDs). Methods are described for imaging LDs ranging in size from 0.1 to...
We present methods for making and testing the membrane biophysics of model lipid droplets (LDs). Methods are described for imaging LDs ranging in size from 0.1 to 40 μm in diameter with high-resolution microscopy and spectroscopy. With known LD compositions, membrane binding, sorting, diffusion, and tension were measured via fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), fluorescence lifetime imaging microscopy (FLIM), atomic force microscopy (AFM), and imaging flow cytometry. Additionally, a custom, small-volume pendant droplet tensiometer is described and used to measure the association of phospholipids to the LD surface. These complementary, cross-validating methods of measuring LD membrane behavior reveal the interplay of biophysical processes on lipid droplet monolayers.
Topics: Lipid Droplets; Microscopy, Atomic Force; Microscopy, Fluorescence; Fluorescence Recovery After Photobleaching; Humans; Flow Cytometry; Spectrometry, Fluorescence
PubMed: 38749444
DOI: 10.1016/j.crmeth.2024.100774 -
Biologics : Targets & Therapy 2024Gene expression, morphology, and electrophysiological combination are essential for assessing the dynamic development of human induced pluripotent stem cell-derived...
Gene Expression, Morphology, and Electrophysiology During the Dynamic Development of Human Induced Pluripotent Stem Cell-Derived Atrial- and Ventricular-Like Cardiomyocytes.
BACKGROUND AND OBJECTIVES
Gene expression, morphology, and electrophysiological combination are essential for assessing the dynamic development of human induced pluripotent stem cell-derived atrial- and ventricular-like cardiomyocytes (iPS-AM and iPS-VM, respectively).
METHODS
For iPS-AM/VM differentiation, we performed the small molecule-based temporal modulation of the retinoic acid and bone morphogenetic protein signaling pathways. We investigated the gene expression and morphology using immunofluorescence, quantitative real-time polymerase chain reaction, flow cytometry, and transmission electron microscopy as well as registered electrophysiological functions using a whole-cell patch clamp on days 20, 30, and 60 post-differentiations.
RESULTS
Pan-cardiomyocyte marker, including troponin T2 () and alpha-actinin-2 (), expressions increased both in iPS-AMs and iPS-VMs. Similarly, the mRNA expression of both iPS-AM-specific markers, ie, natriuretic peptide A (), myosin light chain 7 (), and K+ channel Kir3.4 (), and iPS-VM-specific markers, ie, gap junction α-1 (), myosin light chain 2 (), and alpha-1-subunit of a voltage-dependent L-type calcium channel (), increased from 0 to 20 days, and then decreased from 30 to 60 days. Concerning morphology, cardiac troponin-T (cTnT) arrangement was progressively organized and developed from a disorderly myofibrillar distribution to an organized sarcomere pattern both in iPS-AMs and iPS-VMs. Mitochondrial numbers gradually increased and those of lipid droplets decreased during dynamic development. Regarding physiological function, the resting and action potential amplitudes remained statistically indifferent in both cell types, and the action potential duration was prolonged during the development.
CONCLUSION
IPS-AMs/VMs displayed dynamic development concerning their gene expression, morphology, and electrophysiological function. The discoveries of this study could provide novel insights into heart development and encourage further research.
PubMed: 38746773
DOI: 10.2147/BTT.S448054 -
Frontiers in Endocrinology 2024Diabetic kidney disease (DKD), a significant complication associated with diabetes mellitus, presents limited treatment options. The progression of DKD is marked by... (Review)
Review
Diabetic kidney disease (DKD), a significant complication associated with diabetes mellitus, presents limited treatment options. The progression of DKD is marked by substantial lipid disturbances, including alterations in triglycerides, cholesterol, sphingolipids, phospholipids, lipid droplets, and bile acids (BAs). Altered lipid metabolism serves as a crucial pathogenic mechanism in DKD, potentially intertwined with cellular ferroptosis, lipophagy, lipid metabolism reprogramming, and immune modulation of gut microbiota (thus impacting the liver-kidney axis). The elucidation of these mechanisms opens new potential therapeutic pathways for DKD management. This research explores the link between lipid metabolism disruptions and DKD onset.
Topics: Humans; Diabetic Nephropathies; Lipid Metabolism; Animals; Lipid Metabolism Disorders; Gastrointestinal Microbiome
PubMed: 38742197
DOI: 10.3389/fendo.2024.1336402 -
Fly Dec 2024To identify genes required for brain growth, we took an RNAi knockdown reverse genetic approach in . One potential candidate isolated from this effort is the...
To identify genes required for brain growth, we took an RNAi knockdown reverse genetic approach in . One potential candidate isolated from this effort is the anti-lipogenic gene (). Adp has an established role in the negative regulation of lipogenesis in the fat body of the fly and adipose tissue in mammals. While fat is key to proper development in general, has not been investigated during brain development. Here, we found that RNAi knockdown of in neuronal stem cells and neurons results in reduced brain lobe volume and sought to replicate this with a mutant fly. We generated a novel mutant that acts as a loss-of-function mutant based on buoyancy assay results. We found that despite a change in fat content in the body overall and a decrease in the number of larger (>5 µm) brain lipid droplets, there was no change in the brain lobe volume of mutant larvae. Overall, our work describes a novel mutant that can functionally replace the long-standing mutant and shows that the gene has no obvious involvement in brain growth.
Topics: Animals; Drosophila Proteins; Brain; Drosophila melanogaster; Loss of Function Mutation; RNA Interference; Neurons; Larva; Neural Stem Cells; Drosophila; Adipose Tissue; Mutation
PubMed: 38741287
DOI: 10.1080/19336934.2024.2352938 -
Molecular Metabolism Jul 2024Sulfonylureas (SUs) are still among the mostly prescribed antidiabetic drugs with an established mode of action: release of insulin from pancreatic β-cells. In...
OBJECTIVE
Sulfonylureas (SUs) are still among the mostly prescribed antidiabetic drugs with an established mode of action: release of insulin from pancreatic β-cells. In addition, effects of SUs on adipocytes by activation of the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) have been described, which might explain their insulin-sensitizing potential observed in patients. However, there is a discrepancy between the impact of SUs on antidiabetic action and their rather moderate in vitro effect on PPARγ transcriptional activity. Recent studies have shown that some PPARγ ligands can improve insulin sensitivity by blocking PPARγ Ser-273 phosphorylation without having full agonist activity. It is unknown if SUs elicit their antidiabetic effects on adipocytes by inhibition of PPARγ phosphorylation. Here, we investigated if binding of SUs to PPARγ can interfere with PPARγ Ser-273 phosphorylation and determined their antidiabetic actions in vitro in primary human white adipocytes and in vivo in high-fat diet (HFD) obese mice.
METHODS
Primary human white preadipocytes were differentiated in the presence of glibenclamide, glimepiride and PPARγ ligands rosiglitazone and SR1664 to compare PPARγ Ser-273 phosphorylation, glucose uptake and adipokine expression. Transcriptional activity at PPARγ was determined by luciferase assays, quantification of PPARγ Ser-273 phosphorylation was determined by Western blotting and CDK5 kinase assays. In silico modelling was performed to gain insight into the binding characteristics of SUs to PPARγ. HFD mice were administered SUs and rosiglitazone for 6 days. PPARγ Ser-273 phosphorylation in white adipose tissue (WAT), body composition, glucose tolerance, adipocyte morphology and expression levels of genes involved in PPARγ activity in WAT and brown adipose tissue (BAT) were evaluated.
RESULTS
SUs inhibit phosphorylation of PPARγ at Ser-273 in primary human white adipocytes and exhibit a positive antidiabetic expression profile, which is characterized by up regulation of insulin-sensitizing and down regulation of insulin resistance-inducing adipokines. We demonstrate that SUs directly bind to PPARγ by in silico modelling and inhibit phosphorylation in kinase assays to a similar extend as rosiglitazone and SR1664. In HFD mice SUs reduce PPARγ phosphorylation in WAT and have comparable effects on gene expression to rosiglitazone. In BAT SUs increase UCP1 expression and reduce lipid droplets sizes.
CONCLUSIONS
Our findings indicate that a part of SUs extra-pancreatic effects on adipocytes in vitro and in vivo is probably mediated via their interference with PPARγ phosphorylation rather than via classical agonistic activity at clinical concentrations.
Topics: PPAR gamma; Animals; Phosphorylation; Hypoglycemic Agents; Mice; Sulfonylurea Compounds; Humans; Adipocytes; Male; Serine; Mice, Inbred C57BL; Diet, High-Fat; Cells, Cultured; Insulin Resistance
PubMed: 38735390
DOI: 10.1016/j.molmet.2024.101956 -
Ultrasonics Sonochemistry Jun 2024Partial coalescence is a key factor contributing to the instability of crystalline oil-in-water emulsions in products like dressings and sauces, reducing shelf life. The...
Ultrasound treatment of crystalline oil-in-water emulsions stabilized by sodium caseinate: Impact on emulsion stability through altered crystallization behavior in the oil globules.
Partial coalescence is a key factor contributing to the instability of crystalline oil-in-water emulsions in products like dressings and sauces, reducing shelf life. The intrinsic characteristics of semi-crystalline droplets, including solid fat content, fat crystal arrangement, and polymorphism, play a pivotal role in influencing partial coalescence, challenging prevention efforts even with emulsifiers like amphiphilic proteins. High-intensity ultrasound (HIU) has emerged as an efficient and cost-effective technology for manipulating bulk fat crystallization, thereby enhancing physical properties. This study specifically investigates the impact of HIU treatment on fat crystallization on protein-stabilized crystalline emulsions, utilizing palm olein stearin (POSt) as the lipid phase and sodium caseinate (NaCas) as the surfactant under various HIU powers (100, 150, 200, 300, and 400 W). Results show that increasing HIU power maintained the interfacial potential (-20 mV) provided by NaCas in the emulsions without significant differences. Higher HIU power induced the most stable polymorphic form (β) in the emulsions. Engagingly, the emulsions at 200 W exhibited better storage stability and slower partial coalescence kinetics. Semi-crystalline globules had more uniform and integral crystal clusters that were distributed tangentially near the droplet boundary, perhaps attributed to intermediate subcooling (40.4 °C) at 200 W. The acoustic energy of HIU significantly translates into thermal effects, influencing subcooling degrees as a dominant factor affecting crystallisation in the emulsions. This study establishes ultrasonic crystallization as a novel strategy for modifying the stability of emulsions containing fat crystals.
PubMed: 38735250
DOI: 10.1016/j.ultsonch.2024.106897