Search Results (257)

Alzheimer’s disease (AD) is increasingly recognized as a disorder involving profound mitochondrial dysfunction. Although photobiomodulation (PBM) has shown neuroprotective efficacy in experimental AD models, whether restoration of mitochondrial architecture is mechanistically required for these effects remains unknown. Here, we investigated the role of mitochondrial network remodeling in PBM-mediated neuroprotection in primary mouse hippocampal neurons exposed to amyloid-β (Aβ). Neurons were treated for 24 h with oligomeric Aβ_1–42 and irradiated with 808 nm PBM (100 mW/cm², 30 J/cm²). Mitochondrial morphology was quantified using three-dimensional confocal microscopy and computational network analysis. Aβ exposure induced severe mitochondrial fragmentation and swelling, reflected by increased mitochondrial count and sphericity together with reduced mitochondrial volume, surface area, branch length, and network connectivity. These structural alterations were accompanied by elevated reactive oxygen species production, adenosine triphosphate depletion, membrane depolarization, and reduced neuronal viability. PBM significantly reversed these abnormalities, restoring mitochondrial network integrity and partially normalizing cellular bioenergetics and redox homeostasis. To determine whether mitochondrial dynamics contributes to PBM-induced effects, neurons in another experiment were pre-treated with the dynamin-related protein-1 (DRP-1) mitochondrial division inhibitor-1 (Mdivi-1). The physiological and morphological profiles of the Aβ + PBM + Mdivi-1 and Aβ + Mdivi-1 groups were found to be largely indistinguishable in this case, revealing that PBM failed to restore mitochondrial connectivity, cellular bioenergetics, or viability of neurons in the partially blocked fission–fusion machinery. These findings demonstrate that mitochondrial dynamics is essential for PBM-mediated neuroprotection and identify restoration of mitochondrial network integrity as a crucial mechanism linking PBM to improved neuronal bioenergetics, redox balance, and survival in AD. Full article

High-fat diet (HFD)-induced skeletal muscle atrophy is characterized by impaired muscle mass and function, mitochondrial dysfunction, redox imbalance, and increased inflammation. Previous research has shown that aerobic exercise ameliorates HFD-induced skeletal muscle atrophy, but the underlying mechanisms remain unclear. Dynamin-related protein 1 (Drp1) is a key GTPase that mediates mitochondrial fission, maintains mitochondrial homeostasis, and regulates reactive oxygen species (ROS) production and inflammatory responses. This study investigated the potential involvement of Drp1-associated mitochondrial fission in the protective effects of aerobic exercise against HFD-induced skeletal muscle atrophy. HFD-fed mice underwent an 8-week aerobic exercise intervention, and Mdivi-1, a commonly used mitochondrial fission inhibitor, was administered intraperitoneally to further examine the involvement of mitochondrial fission. Assessments included grip strength, endurance testing, body composition, histology, transmission electron microscopy, immunofluorescence, DHE staining, antioxidant assays, Western blotting, and qPCR. Aerobic exercise reduced Drp1 phosphorylation, oxidative stress, and inflammatory responses in the skeletal muscle of HFD-fed mice and attenuated skeletal muscle atrophy. Mdivi-1 treatment produced similar protective effects, including attenuation of skeletal muscle atrophy, oxidative stress, and inflammatory responses. Together, these findings suggest that Drp1 phosphorylation and associated mitochondrial fission may contribute to the protective effects of aerobic exercise against HFD-induced skeletal muscle atrophy. Full article

Hepatitis B virus (HBV) exploits host proteins to reshape cellular physiology and metabolism, thereby supporting its replication. Transgelin (TAGLN), an actin-binding protein highly expressed in HBV-associated hepatocellular carcinoma, has a poorly defined role in HBV infection. HBV infection upregulated TAGLN expression both in vitro and in vivo. Silencing TAGLN suppressed HBV replication, increased mitochondrial fission, and elevated intracellular ATP levels. Mitochondrial proteomic analysis identified optic atrophy 1 (OPA1), a mitochondrial dynamin protein, as differentially expressed, with higher levels in HBV-positive HepG2.2.15 cells than in parental HepG2 cells. TAGLN deficiency was associated with reduced OPA1 expression. Similarly, modulation of OPA1 expression was associated with corresponding changes in TAGLN levels and HBV replication. Collectively, these findings indicate an association between TAGLN and OPA1 in the context of HBV replication. However, the precise regulatory hierarchy and molecular basis of this association remain to be determined. Full article

Amyotrophic lateral sclerosis (ALS) is a neuromuscular disease characterized by progressive motor neuron (MN) degeneration and severe skeletal muscle atrophy. Despite extensive research, the mechanisms driving disease onset and progression remain incompletely understood. While MN loss is a defining feature of ALS, increasing evidence indicates that mitochondrial dysfunction contributes to disease pathogenesis. Here, we investigated the hypothesis that Mdivi-1, a pharmacological inhibitor of mitochondrial fission protein Drp-1, may exert neuroprotective properties in the SOD1^G93A mouse model of ALS. Treatment was initiated prior to symptomatic onset to assess its potential disease-modifying effects. Mdivi-1 administration resulted in partial preservation of spinal MNs, however, this benefit did not translate into functional improvement. Moreover, treated animals exhibited exacerbated muscle atrophy, increased cytoplasmic localization of TDP-43 in MNs and compromised synaptic plasticity. Drp-1 expression was reduced in SOD1 mice and further decreased following Mdivi-1 treatment, suggesting that mitochondrial dynamics may already be compromised in this model. Overall, our results also highlight possible off-target effects of Mdivi-1 and point to a context-dependent role of mitochondrial dynamics in ALS. Full article

The liver ranks among the peripheral organs exhibiting the most robust circadian rhythmicity, with glucose homeostasis, lipid metabolism, and bile acid turnover governed by tightly phased diurnal oscillations. Mitochondria execute these programs, their output coordinated with the hepatocyte circadian state. The mitochondrial network undergoes dynamic remodeling across the 24 h cycle, encompassing oscillatory changes in bioenergetics, fusion–fission balance, and quality control. This interplay is bidirectional: core clock components drive rhythmic remodeling via cyclin-dependent kinase 1/mitogen-activated protein kinase (CDK1/MAPK)-dependent phosphorylation of dynamin-related protein 1 (DRP1) and the NAD⁺–SIRT1/SIRT3 axis, while retrograde signals modulate clock amplitude and entrainment. Circadian disruption is associated with mitochondrial dysfunction implicated in MASLD onset and progression to MASH and HCC, though this evidence remains largely correlative and derives predominantly from rodent models. This review integrates clock–mitochondria coupling with metabolic liver disease. Restoring this coupling has been proposed as a candidate chronotherapeutic strategy, supported by preliminary rhythmicity data in primary human hepatocytes and a hepatocellular carcinoma cell line, though causal validation in healthy human liver is lacking. Time-restricted feeding, NAD⁺ precursors, PPAR agonists, and ACC inhibitors converge on clock-regulated pathways and may benefit from circadian-informed timing, though this remains unverified. Full article

Global plastic production has led to widespread contamination by micro- and nanoplastics, with polystyrene nanoplastics (PSNPs) increasingly being detected in human biological samples, including blood and cardiac tissue. Given the critical role of mitochondria in cardiac energy metabolism, this study investigated whether 100 nm PSNPs interact with mitochondria and affect mitochondrial function in H9c2 cardiomyoblasts. Cellular uptake and intracellular distribution were examined, followed by an evaluation of mitochondrial ultrastructure, intracellular and mitochondrial reactive oxygen species (ROS) production, mitochondrial membrane potential, mitochondrial dynamics and mitophagy-related gene expression, mitochondrial DNA copy number, and metabolic function. PSNPs were internalized but did not directly localize to mitochondria within 24 h. No significant cytotoxicity, increase in intracellular or mitochondrial ROS production, or alteration in basal metabolic activity was observed. However, PSNP exposure resulted in intracellular accumulation, an altered mitochondrial ultrastructure characterized by crista loosening and vacuole-like structural changes. These changes were accompanied by reduced mitochondrial membrane potential; the upregulation of mitochondrial dynamics-related genes, including optic atrophy 1 (Opa1) and dynamin-related protein 1 (Drp1); the suppression of PTEN-induced kinase 1 (PINK1)/Parkin RBR E3 ubiquitin protein ligase (Parkin)-mediated mitophagy-related genes; and decreased maximal respiratory capacity. Lactate production and the extracellular acidification rate remained unchanged, suggesting that compensatory glycolysis was not activated. These findings indicate that PSNP exposure induces early mitochondrial structural and functional alterations without substantial cell damage, suggesting a potential reduction in cardiac adaptive capacity under PSNP-induced stress conditions. Full article

Reparative macrophage polarization and macrophage-derived reactive oxygen species (ROS) are required for ischemia-induced revascularization in peripheral artery disease (PAD). Our previous study showed that mitochondrial fission protein dynamin-related protein 1 (DRP1) promotes reparative polarization and metabolic reprogramming in macrophages and post-ischemic neovascularization. However, the redox-dependent mechanism governing DRP1 activation in this context remains elusive. Here, using a mouse hindlimb ischemia (HLI) model of PAD, we identify cysteine sulfenylation (CysOH) of DRP1 as a critical redox modification induced in ischemic bone marrow (BM)-derived cells. BM chimeric mice reconstituted with CRISPR/Cas9-generated “redox-dead” DRP1-C631A knock-in mutant (Drp1^C/A) BM exhibited markedly reduced limb perfusion recovery and CD31⁺ capillary density in ischemic muscles following HLI. These defects were associated with enhanced Ly6G⁺ neutrophil accumulation, pro-inflammatory F4/80⁺CD80⁺ M1-like macrophages and reduced anti-inflammatory F4/80⁺CD206⁺ M2-like macrophages in ischemic muscle. Mechanistically, using an in vitro PAD model, hypoxia serum starvation (HSS) rapidly induced NADPH oxidase 2-dependent cytosolic ROS production and DRP1-CysOH formation in wild-type macrophages. In contrast, Drp1^C/A macrophages failed to undergo DRP1-CysOH-dependent mitochondrial fission under HSS, resulting in aberrant metabolic reprogramming characterized by enhanced glycolysis and mitochondrial ROS, pro-inflammatory p-NF-κB and M1-genes, and suppressed anti-inflammatory p-AMPK, efferocytosis and M2-genes. Thus, our findings establish DRP1 sulfenylation as a previously unrecognized redox-sensing mechanism that links ischemia-induced ROS to reparative macrophage reprogramming and revascularization, identifying a novel therapeutic target for PAD. Full article

Dynamin-related protein 1 (Drp1) is essential for mitochondrial dynamics in skeletal muscle, particularly in regulating fission, mitophagy, and maintaining mitochondrial function. Exercise is crucial for sustaining muscle function, promoting mitochondrial adaptations that enhance energy metabolism and oxidative capacity in skeletal muscle. In this Review, we discuss the role of Drp1 in exercise-induced mitochondrial adaptations and its potential implications for skeletal muscle health. We first address the evidence that Drp1 activity must be maintained within a narrow physiological range. Both Drp1 deficiency and overabundance provoke muscle atrophy and dysfunction, establishing a Goldilocks principle for mitochondrial fission. We then examine the multi-layered post-translational modification code that governs Drp1 activity, including canonical phosphorylation, redox-sensing modifications, and the receptor selectivity model that may specify distinct fission programs. A three-stage model of exercise-induced mitochondrial adaptation is presented, describing how Drp1 activity is temporally orchestrated from acute fragmentation through short-term remodeling to long-term network optimization, and how these morphological transitions govern substrate metabolism and determine exercise performance. The pathological consequences of Drp1 dysregulation are examined in metabolic disease, where Drp1 is chronically hyperactivated, and in aging, where Drp1 activity is deficient. Finally, we analyze the ROS-Drp1 signaling axis as the mechanistic basis for the bidirectional regulation of Drp1 by exercise. Moderate exercise-induced ROS production activates Nrf2 and AMPK signaling, which suppress excessive fission in metabolic disease while restoring insufficient fission in aging, thereby moving Drp1 activity toward the physiological Goldilocks zone in both contexts. This context-dependent, bidirectional regulation distinguishes exercise from pharmacological inhibitors and identifies the ROS-Drp1 axis as a therapeutic target for conditions at opposite ends of the Drp1 activity continuum, such as sarcopenia and type 2 diabetes. Full article

Early-life nutrition is critical for the development and health of dairy calves, necessitating alternatives to in-feed antibiotics. This study investigated whether dietary glycerol monolaurate (GML) enhances growth performance, reduces diarrhea incidence, improves systemic antioxidant and immune status, and modulates hepatic immunometabolic function in calves. Twenty-four Holstein bull calves (7 ± 0.5 d of age) were randomly assigned by body weight and age to a control group or a GML-supplemented group, both fed milk replacer with starter feed provided throughout the 45-day trial. Calves in the GML group received GML at a dosage of 100 mg/kg of body weight, mixed into the milk replacer prior to feeding. Calves in the GML group had significantly greater final body weight, average daily gain, and starter intake during the latter period (d 23–45) compared with the control group. GML supplementation also significantly reduced the incidence of diarrhea and fever, alongside lower fecal scores and fewer antibiotic treatments. Plasma analysis revealed enhanced antioxidant capacity, as indicated by increased total antioxidant capacity and glutathione peroxidase, along with an improved immune profile characterized by elevated immunoglobulin G and reduced interleukin-2. Transcriptomic analysis of the liver showed that GML upregulated genes and pathways related to innate antiviral immunity, such as radical S-adenosyl methionine domain containing 2, interferon-stimulated gene 15, and MX dynamin like GTPase 1. Lipidomics further indicated that GML induced a targeted remodeling of hepatic lipids, including increased diacylglycerols and triacylglycerols and decreased specific phospholipids and sphingolipids, suggesting a metabolic shift supportive of immune activation and inflammatory control. In conclusion, dietary GML enhances growth and health in suckling calves, which is mediated through a coordinated immunometabolic reprogramming in the liver. GML represents a promising functional fat additive for sustainable calf rearing. Full article

Although evolutionarily distant, the bacteria Listeria monocytogenes, Shigella flexneri, and Burkholderia thailandensis each undergo a “cell-to-cell” spreading process that allows these pathogens to disseminate within human tissues. Spread initiates when bacteria polymerize actin filaments that propel them through the host cell cytosol. The pathogens then remodel the plasma membrane into protrusions that are internalized by adjacent cells and resolved into double membranous vacuoles (DMVs) which lyse to liberate bacteria. In this review, we discuss recent publications indicating that L. monocytogenes, S. flexneri, and B. thailandensis each enhance their spread by altering the subcellular localization of human Dynamin 2—a GTPase that regulates endocytosis and other trafficking pathways. Interestingly, Dynamin 2 controls distinct steps in spread of L. monocytogenes, S. flexneri, and B. thailandensis. In the case of L. monocytogenes, the GTPase has the potential to restrict protrusion formation by generating tension at tight junctions. However, L. monocytogenes secretes a protein that relieves this restriction of protrusions, allowing efficient spread. During dissemination of S. flexneri and B. thailandensis, Dynamin 2 is co-opted to resolve protrusions into DMVs. B. thailandensis also mobilizes Dynamin 2 to lyse DMVs. These findings highlight diverse ways in which bacteria control Dynamin 2 to augment spread. Full article

Centronuclear myopathy (CNM) is a genetically heterogenous congenital myopathy traditionally classified as a membrane remodeling disorder. Emerging evidence reveals that centronuclear myopathy mutations converge upon common cellular dysfunction extending beyond membrane trafficking. This review proposes a unified model positioning CNM as a disorder of impaired organelle communication and structural crosstalk. We focus on how mutations in Myotubularin1 (MTM1) and gain-of-function mutations in Dynamin 2 (DNM2) disrupt the triad architecture, leading to aberrant calcium handling, mitochondrial dysfunction, imbalanced reactive oxygen species (ROS) production, and defective autophagy. These dysfunctions are not isolated but form a pathological feedback loop that compromises muscle integrity and regeneration. By identifying shared mechanisms across CNM types, this review positions the disorder as the convergence of organelle stress and cytoskeletal network failure. This perspective reveals novel therapeutic strategies based on the principle that targeting a central pathological node may alleviate systemic dysfunction. However, given the complexity of the organelle feedback loop, a comprehensive, multi-target approach may ultimately be required to achieve full phenotypic rescue across all affected tissues. Full article

The differentiation of dental papilla cells (DPCs) into functional odontoblasts is critical for dentinogenesis, yet the role of mitochondrial dynamics remains unclear. Here, we investigated the functional role of mitochondrial fission and mitochondria-associated endoplasmic reticulum membranes (MAMs) in the odontogenic differentiation of DPCs. Using in vitro differentiation models combined with confocal microscopy, transmission electron microscopy, and gain- and loss-of-function approaches, we found that odontogenic induction triggered early mitochondrial fragmentation and increased MAM formation. Dynamin-related protein 1 (DRP1) mediated mitochondrial fission, which in turn regulated MAM architecture and promoted differentiation. Malic enzyme 2 (ME2) acted as an upstream regulator, facilitating DRP1 recruitment and organizing MAM integrity. Notably, disruption of the ME2-DRP1-MAM axis impaired dentin formation both in vitro and in vivo, either by ME2 knockdown or pharmacological inhibition of DRP1 (Mdivi-1). These findings establish the ME2-DRP1-MAM axis as a critical metabolic–organellar switch driving odontoblast differentiation, providing new mechanistic insights into dentinogenesis and identifying potential therapeutic targets for dentin–pulp complex regeneration. Full article

Myostatin is associated with inflammatory processes; however, its renal expression and impact on mitochondrial homeostasis during chronic kidney disease (CKD) remain poorly defined. This study investigated whether omega-3 fatty acids (FAs) modulate renal myostatin and mitochondrial integrity under uremic conditions using both in vivo and in vitro models. In rats with adenine-induced CKD, omega-3 FA supplementation attenuated the increase in renal myostatin expression. Uremia was associated with impaired mitochondrial homeostasis, evidenced by decreased peroxisome proliferator-activated receptor gamma coactivator-1 alpha levels and increased dynamin-related protein 1 levels, alongside the upregulation of mitophagy and inflammatory markers. Furthermore, mitochondrial structural damage and reduced mitochondrial DNA (mtDNA) content were observed in uremic kidneys. Omega-3 FA treatment partially reversed these alterations, restored mtDNA levels, and preserved mitochondrial cristae integrity. In vitro, HK-2 cells treated with indoxyl sulfate exhibited increases in myostatin expression and mitochondrial impairment, which were mitigated by eicosapentaenoic acid, docosahexaenoic acid, or their combination. These findings suggest that omega-3 FAs exert protective effects against uremia-induced renal injury by suppressing myostatin and preserving mitochondrial homeostasis, specifically by modulating biogenesis, dynamics, and structural integrity. Consequently, omega-3 FAs may serve as a potential therapeutic strategy with which to preserve mitochondrial homeostasis in patients with CKD. Full article

Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation, epithelial barrier disruption and immune dysfunction. Alleviating and curing these pathological manifestations is the goal of IBD treatment. Despite substantial advances in targeted immunotherapies and anti-inflammatory strategies, achieving sustained intestinal mucosal healing remains a major clinical challenge. Dynamin-related protein 1 (Drp1) is a GTPase that mediates mitochondrial fission and plays a crucial role in maintaining the dynamic balance of mitochondrial morphology and function. In IBD, Drp1 expression is frequently upregulated and continuously activated, resulting in excessive fission and fragmentation of mitochondria. This mitochondrial dysregulation contributes to ATP depletion and excessive reactive oxygen species (ROS) production, thereby exacerbating disease progression and amplifying inflammatory signaling. This review highlights the distinctive role of Drp1 as an integrative node in IBD. Specifically, we connect mitochondrial dynamics with epithelial barrier failure, immune dysregulation, inflammatory cell death, and intestinal microenvironment remodeling. We further emphasize the potential relevance of Drp1 for biomarker-based patient stratification and mechanism-informed therapeutic targeting, thereby distinguishing this review from more descriptive accounts of mitochondrial dysfunction in intestinal inflammation. Full article

Background/Objectives: Mitochondria are dynamic organelles that continuously undergo balanced cycles of fusion and division to maintain optimal function. Mitochondrial division is mediated by Dynamin-Related Protein 1 (DRP1), a cytosolic large GTPase whose phosphorylation at serine 616 (DRP1-S616Ⓟ) promotes its translocation to the outer mitochondrial membrane and organelle division. Dysregulated mitochondrial division disrupts cellular homeostasis and contributes to disease pathogenesis, including cancer. Our prior work demonstrated that the oncogene-induced mitogen-activated protein kinase (MAPK) pathway constitutively phosphorylates DRP1 at serine 616, which is essential to cellular transformation and correlates with oncogene status in patient tissues. Similarly, DRP1-S616Ⓟ is subject to pharmacologic control by targeted therapies against oncogenic MAPK signaling. Methods: Building upon this foundation, we developed and characterized a recombinant murine monoclonal antibody (referred to as 3G11) with high specificity for human DRP1-S616Ⓟ, raised against a peptide derived from the human DRP1 sequence. Results: Using diverse experimental platforms, we demonstrate the robust utility of 3G11 to detect DRP1-S616Ⓟ in melanoma cell extracts and isolated organelles. Immunofluorescence revealed that pharmacologic inhibition of oncogenic MAPK signaling reduces DRP1-S616Ⓟ levels, which correlates with mitochondrial hyperfusion, while immunohistochemistry showed that elevated DRP1-S616Ⓟ expression in human tissues correlates with BRAF^V600E disease. Conclusions: 3G11 is a new recombinant antibody for detecting DRP1-S616Ⓟ and supports studies of mitochondrial division in cancer. Together, these findings establish 3G11 as a specific, versatile, renewable, and cost-effective tool for studying mitochondrial division, with strong potential for clinical applications. Full article