Search Results (17)

Non-alcoholic steatohepatitis (NASH), a progressive liver disease characterized by lipid accumulation and chronic inflammation, lacks effective therapies targeting its multifactorial pathogenesis. This study investigates marine-derived chondroitin sulfate (CS) as a multi-organelle modulator capable of regulating lipid metabolism, oxidative stress, and inflammation in NASH. By employing subcellular imaging and organelle-specific labeling techniques, we demonstrate that CS restores lysosomal acidification in a NASH model, enabling the reduction of lipid droplets via lysosomal–lipid droplet fusion. Concurrently, CS upregulates dynamin-related protein 1 (DRP1), driving mitochondrial terminal fission to spatially isolate reactive oxygen species (ROS) segments for mitophagy, thereby reducing ROS levels. Notably, pharmacological inhibition of lysosomal activity using chloroquine or bafilomycin A1 abolished the therapeutic effects of CS, confirming lysosomal acidification as an essential prerequisite. Collectively, these findings reveal the potential of CS as a therapeutic agent for NASH and provide critical insights into the subcellular mechanisms underlying its protective effects, thus offering a foundation for future research and therapeutic development. Full article

Dynamin-related protein 1 (Drp1) is a crucial player in mitochondrial fission and liver function. The interactions between mitochondria, endoplasmic reticulum (ER), and lipid droplets (LDs) are fundamental for lipid metabolism. This study utilized liver-specific Drp1 knockout (Drp1LiKO) mice to investigate the effects of Drp1 deficiency on organelle interactions, metabolism, and inflammation. Our analysis revealed disrupted interactions between mitochondria and LDs, as well as altered interactions among ER, mitochondria, and LDs in Drp1LiKO mice. Through mass spectrometry and microarray analysis, we identified changes in lipid profiles and perturbed expression of lipid metabolism genes in the livers of Drp1LiKO mice. Further in vitro experiments using primary hepatocytes from Drp1LiKO mice confirmed disturbances in lipid metabolism and increased inflammation. These findings highlight the critical involvement of Drp1 in regulating organelle interactions for efficient lipid metabolism and overall liver health. Targeting Drp1-mediated organelle interactions may offer potential for developing therapies for liver diseases associated with disrupted lipid metabolism. Full article

We investigated whether the elimination of two major enzymes responsible for triacylglycerol synthesis altered the structure and physical state of organelle membranes under mild heat shock conditions in the fission yeast, Schizosaccharomyces pombe. Our study revealed that key intracellular membrane structures, lipid droplets, vacuoles, the mitochondrial network, and the cortical endoplasmic reticulum were all affected in mutant fission yeast cells under mild heat shock but not under normal growth conditions. We also obtained direct evidence that triacylglycerol-deficient cells were less capable than wild-type cells of adjusting their membrane physical properties during thermal stress. The production of thermoprotective molecules, such as HSP16 and trehalose, was reduced in the mutant strain. These findings suggest that an intact system of triacylglycerol metabolism significantly contributes to membrane protection during heat stress. Full article

Lipid droplet (LD) accumulation in hepatocytes is one of the major symptoms associated with fatty liver disease. Mitochondria play a key role in catabolizing fatty acids for energy production through β-oxidation. The interplay between mitochondria and LD assumes a crucial role in lipid metabolism, while it is obscure how mitochondrial morphology affects systemic lipid metabolism in the liver. We previously reported that cilnidipine, an already existing anti-hypertensive drug, can prevent pathological mitochondrial fission by inhibiting protein–protein interaction between dynamin-related protein 1 (Drp1) and filamin, an actin-binding protein. Here, we found that cilnidipine and its new dihydropyridine (DHP) derivative, 1,4-DHP, which lacks Ca²⁺ channel-blocking action of cilnidipine, prevent the palmitic acid-induced Drp1–filamin interaction, LD accumulation and cytotoxicity of human hepatic HepG2 cells. Cilnidipine and 1,4-DHP also suppressed the LD accumulation accompanied by reducing mitochondrial contact with LD in obese model and high-fat diet-fed mouse livers. These results propose that targeting the Drp1–filamin interaction become a new strategy for the prevention or treatment of fatty liver disease. Full article

Distal sensory polyneuropathy (DSP) and distal neuropathic pain (DNP) remain significant challenges for older people with HIV (PWH), necessitating enhanced clinical attention. HIV and certain antiretroviral therapies (ARTs) can compromise mitochondrial function and impact mitochondrial DNA (mtDNA) replication, which is linked to DSP in ART-treated PWH. This study investigated mtDNA, mitochondrial fission and fusion proteins, and mitochondrial electron transport chain protein changes in the dorsal root ganglions (DRGs) and sural nerves (SuNs) of 11 autopsied PWH. In antemortem standardized assessments, six had no or one sign of DSP, while five exhibited two or more DSP signs. Digital droplet polymerase chain reaction was used to measure mtDNA quantity and the common deletions in isolated DNA. We found lower mtDNA copy numbers in DSP+ donors. SuNs exhibited a higher proportion of mtDNA common deletion than DRGs in both groups. Mitochondrial electron transport chain (ETC) proteins were altered in the DRGs of DSP+ compared to DSP− donors, particularly Complex I. These findings suggest that reduced mtDNA quantity and increased common deletion abundance may contribute to DSP in PWH, indicating diminished mitochondrial activity in the sensory neurons. Accumulated ETC proteins in the DRG imply impaired mitochondrial transport to the sensory neuron’s distal portion. Identifying molecules to safeguard mitochondrial integrity could aid in treating or preventing HIV-associated peripheral neuropathy. Full article

Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of lipids within hepatocytes, which compromises liver functionality following mitochondrial dysfunction and increased production of reactive oxygen species (ROS). Lipoic acid is one of the prosthetic groups of the pyruvate dehydrogenase complex also known for its ability to confer protection from oxidative damage because of its antioxidant properties. In this study, we aimed to investigate the effects of lipoic acid on lipotoxicity and mitochondrial dynamics in an in vitro model of liver steatosis. HepG2 cells were treated with palmitic acid and oleic acid (1:2) to induce steatosis, without and with 1 and 5 µM lipoic acid. Following treatments, cell proliferation and lipid droplets accumulation were evaluated. Mitochondrial functions were assessed through the evaluation of membrane potential, MitoTracker Red staining, expression of genes of the mitochondrial quality control, and analysis of energy metabolism by HPLC and Seahorse. We showed that lipoic acid treatment restored membrane potential to values comparable to control cells, as well as protected cells from mitochondrial fragmentation following PA:OA treatment. Furthermore, our data showed that lipoic acid was able to determine an increase in the expression of mitochondrial fusion genes and a decrease in mitochondrial fission genes, as well as to restore the bioenergetics of cells after treatment with palmitic acid and oleic acid. In conclusion, our data suggest that lipoic acid reduces lipotoxicity and improves mitochondrial functions in an in vitro model of steatosis, thus providing a potentially valuable pharmacological tool for NAFLD treatment. Full article

Oocyte vitrification is crucial for livestock reproduction, germplasm conservation, and human-assisted reproduction, but the overabundance of lipids is highly detrimental to oocyte development. It is necessary to reduce the lipid droplet content of oocytes before cryopreservation. This study analyzed the impact of β-nicotinamide mononucleotide (NMN), berberine (BER), or cordycepin (COR) on various aspects of bovine oocytes, including lipid droplet content and the expression levels of genes related to lipid synthesis in bovine oocytes, development ability, reactive oxygen species (ROS), apoptosis, and the expression levels of genes associated with endoplasmic reticulum (ER) stress, and mitochondrial function in vitrified bovine oocytes. The results of our study indicated that 1 μM NMN, 2.5 μM BER, and 1 μM COR were effective in reducing the lipid droplet content and suppressing the expression levels of genes involved in lipid synthesis in bovine oocytes. Our findings showed that the vitrified bovine oocytes treated with 1 μM of NMN had a significantly higher survival rate and better development ability compared to the other vitrified groups. Additionally, 1 μM NMN, 2.5 μM BER, and 1 μM COR decreased the levels of ROS and apoptosis, decreased the mRNA expression levels of genes involved in ER stress and mitochondrial fission but increased the mRNA expression levels of genes associated with mitochondrial fusion in the vitrified bovine oocytes. Our study results suggested that 1 μM NMN, 2.5 μM BER, and 1 μM COR effectively decreased the lipid droplet content and enhanced the development ability of vitrified bovine oocytes by lowering ROS levels, reducing ER stress, regulating mitochondrial function, and inhibiting apoptosis. Furthermore, the results showed that 1 μM NMN was more effective than 2.5 μM BER and 1 μM COR. Full article

Strontium, the main component of radioactive nuclear wastewater, is characterized by a high fission yield and an extended half-life. It is easily absorbed by the human body, thus greatly threatening the environment and the human body. In this study, a mesoporous composite phase sodium superionic conductor (NVP@NMP) was synthesized by the droplet template method, and the rapid capture of Sr²⁺ from wastewater was achieved by constructing a nano-heterogeneous interface to increase the ion diffusion rate. NVP@NMP showed efficient and rapid removal of strontium ions in adsorption kinetics, isothermal adsorption, solution pH, and interfering ions concentration tests, especially using the equilibrium time of 2 min for strontium absorption by NVP@NMP and a maximum theoretical adsorption capacity of 361.36 mg/g. The adsorption process was spontaneous, endothermic, and feasible. At higher concentrations of other competing ions (Na, K, Ca, Mg, and Cs), the adsorbent exhibited higher selectivity towards Sr²⁺.TEM, XPS, and XRD analyses revealed that ion exchange was the main mechanism for the NVP@NMP ultrafast adsorption of Sr²⁺. In this research, we investigated the feasibility of ultrafast strontium capture by sodium superionic conductor structured phosphates and explained the ultrafast strontium adsorption mechanism of NASICON materials through XPS. Full article

Transmembrane proteins (TMEMs) are integral proteins that span biological membranes. TMEMs function as cellular membrane gates by modifying their conformation to control the influx and efflux of signals and molecules. TMEMs also reside in and interact with the membranes of various intracellular organelles. Despite much knowledge about the biological importance of TMEMs, their role in metabolic regulation is poorly understood. This review highlights the role of a single TMEM, transmembrane protein 135 (TMEM135). TMEM135 is thought to regulate the balance between mitochondrial fusion and fission and plays a role in regulating lipid droplet formation/tethering, fatty acid metabolism, and peroxisomal function. This review highlights our current understanding of the various roles of TMEM135 in cellular processes, organelle function, calcium dynamics, and metabolism. Full article

In the presence of high abundance of exogenous fatty acids, cells either store fatty acids in lipid droplets or oxidize them in mitochondria. In this study, we aimed to explore a novel and direct role of mitochondrial fission in lipid homeostasis in HeLa cells. We observed the association between mitochondrial morphology and lipid droplet accumulation in response to high exogenous fatty acids. We inhibited mitochondrial fission by silencing dynamin-related protein 1(DRP1) and observed the shift in fatty acid storage-usage balance. Inhibition of mitochondrial fission resulted in an increase in fatty acid content of lipid droplets and a decrease in mitochondrial fatty acid oxidation. Next, we overexpressed carnitine palmitoyltransferase-1 (CPT1), a key mitochondrial protein in fatty acid oxidation, to further examine the relationship between mitochondrial fatty acid usage and mitochondrial morphology. Mitochondrial fission plays a role in distributing exogenous fatty acids. CPT1A controlled the respiratory rate of mitochondrial fatty acid oxidation but did not cause a shift in the distribution of fatty acids between mitochondria and lipid droplets. Our data reveals a novel function for mitochondrial fission in balancing exogenous fatty acids between usage and storage, assigning a role for mitochondrial dynamics in control of intracellular fuel utilization and partitioning. Full article

Biomolecular condensates, which assemble via the process of liquid–liquid phase separation (LLPS), are multicomponent compartments found ubiquitously inside cells. Experiments and simulations have shown that biomolecular condensates with many components can exhibit multilayered organizations. Using a minimal coarse-grained model for interacting multivalent proteins, we investigate the thermodynamic parameters governing the formation of multilayered condensates through changes in protein valency and binding affinity. We focus on multicomponent condensates formed by scaffold proteins (high-valency proteins that can phase separate on their own via homotypic interactions) and clients (proteins recruited to condensates via heterotypic scaffold–client interactions). We demonstrate that higher valency species are sequestered to the center of the multicomponent condensates, while lower valency proteins cluster towards the condensate interface. Such multilayered condensate architecture maximizes the density of LLPS-stabilizing molecular interactions, while simultaneously reducing the surface tension of the condensates. In addition, multilayered condensates exhibit rapid exchanges of low valency proteins in and out, while keeping higher valency proteins—the key biomolecules involved in condensate nucleation—mostly within. We also demonstrate how modulating the binding affinities among the different proteins in a multicomponent condensate can significantly transform its multilayered structure, and even trigger fission of a condensate into multiple droplets with different compositions. Full article

Obesity is an alarming yet increasing phenomenon worldwide, and more effective obesity management strategies have become essential. In addition to the numerous anti-adipogenic treatments promising a restauration of a healthy white adipose tissue (WAT) function, numerous studies reported on the critical role of nutritional parameters in obesity development. In a metabolic disorder context, a better control of nutrient intake is a key step in slowing down adipogenesis and therefore obesity. Of interest, the effect on WAT remodeling deserves deeper investigations. Among the different actors of WAT plasticity, the mitochondrial network plays a central role due to its dynamics and essential cellular functions. Hence, the present in vitro study, conducted on the 3T3-L1 cell line, aimed at evaluating the incidence of modulating the carbohydrates intake on adipogenesis through an integrated assessment of mitochondrial structure, dynamics, and functions-correlated changes. For this purpose, our experimental strategy was to compare the occurrence of adipogenesis in 3T3-L1 cells cultured either in a high-glucose (HG) medium (25 mM) or in a low-glucose (LG) medium (5 mM) supplemented with equivalent galactose (GAL) levels (20 mM). The present LG-GAL condition was associated, in differentiating adipocytes, to a reduced lipid droplet network, lower expressions of early and late adipogenic genes and proteins, an increased mitochondrial network with higher biogenesis marker expression, an equilibrium in the mitochondrial fusion/fission pattern, and a decreased expression of mitochondrial metabolic overload protein markers. Therefore, those main findings show a clear effect of modulating glucose accessibility on 3T3-L1 adipogenesis through a combined effect of adipogenesis modulation and overall improvement of the mitochondrial health status. This nutritional approach offers promising opportunities in the control and prevention of obesity. Full article

Droplet fission has gained notable interest in drug delivery applications due to its ability to perform parallel operations in single device. Hitherto, droplet flow behavior in a 3D constriction was scarcely investigated. This study aims to investigate droplets fission inside a 3D bi-planar multifurcated microfluidic device. The flow behavior and droplet size distribution were studied in trifurcated microchannels using distilled water as dispersed phase (1 mPa·s) and olive oil (68 mPa·s) as continuous phase. Various sizes of subordinate daughter droplets were manipulated passively through the modulation of flowrate ratio (Q) (0.15 < Q < 3.33). Overall, we found droplet size coefficient of variations (CV%) ranging from 0.72% to 69%. Highly monodispersed droplets were formed at the upstream T-junction (CV% < 2%) while the droplet fission process was unstable at higher flowrate ratio (Q > 0.4) as they travel downstream (1.5% < CV% < 69%) to splitting junctions. Complex responses to the non-monotonic behavior of mean droplet size was found at the downstream boundaries, which arose from the deformations under nonuniform flow condition. CFD was used as a tool to study the preliminary maximum velocity (U_max) profile for the symmetrical (0.01334 m/s < U_max < 0.0153 m/s) and asymmetrical branched channels (0.0223 m/s< U_max < 0.00438 m/s), thus complementing the experimental model studies. Full article

Breakup of droplets at bi-layer bifurcating junction in polydimethylsiloxane (PDMS) microchannel has been investigated by experiments and numerical simulation. The pressure drop in bi-layer bifurcating channel was investigated and compared with single-layer bifurcating channel. Daughter droplet size variation generated in bi-layer bifurcating microchannel was analyzed. The correlation was proposed to predict the transition between breakup and non-breakup conditions of droplets in bi-layer bifurcating channel using a phase diagram. In the non-breakup regime, droplets exiting port can be switched via tuning flow resistance by controlling radius of curvature, and or channel height ratio. Compared with single-layer bifurcating junction, 3-D cutting in diagonal direction from bi-layer bifurcating junction induces asymmetric fission to form daughter droplets with distinct sizes while each size has good monodispersity. Lower pressure drop is required in the new microsystem. The understanding of the droplet fission in the novel microstructure will enable more versatile control over the emulsion formation, fission and sorting. The model system can be developed to investigate the encapsulation and release kinetics of emulsion templated particles such as drug encapsulated microcapsules as they flow through complex porous media structures, such as blood capillaries or the porous tissue structures, which feature with bifurcating junctions. Full article

This paper demonstrates a low cost fabrication approach for microscale droplet fission and encapsulation. Using a modified xurography method, rapid yet reliable microfluidic devices with flexible designs (single layer and double layer) are developed to enable spatial control of droplet manipulation. In this paper, two different designs are demonstrated, i.e., droplet fission (single layer) and droplet encapsulation (double layer). In addition, the current fabrication approach reduces the overall production interval with the introduction of a custom-made polydimethylsiloxane (PDMS) aligner. Apart from that, the fabricated device is able to generate daughter droplets with the coefficient of variance (CV) below 5% and double emulsions with CV maintained within 10% without involvement of complex surface wettability modification. Full article