Ovarian aging is characterized by granulosa cell (GC) dysfunction and compromised oocyte maturation, yet effective mitochondria-targeted interventions remain limited. We investigated the association of the mitochondrial fusion promoter M1 with age-related transcriptional, mitochondrial, and metabolic phenotypes. Reanalysis of public single-cell transcriptomic data identified age-associated differences in a granulosa-enriched cluster across mitochondrial dynamics-related, glycolysis/lactate metabolic, bioenergetic/TCA-cycle, and granulosa-cell phenotype programs. RT-qPCR in early-passage, late-passage, and M1-treated late-passage HGL5 cells showed partial concordance with this transcriptomic framework. In late-passage HGL5 cells, M1 treatment induced a less fragmented, elongation-associated mitochondrial morphology accompanied by altered DRP1 phosphorylation, increased per-well respiratory readouts, and increased ATP fluorescence. In ex vivo aged oocytes, M1 increased polar body extrusion and was associated with reduced DCFDA fluorescence and increased CMXRos fluorescence. These findings indicate that M1 is associated with mitochondrial and metabolic remodeling in a late-passage HGL5 model displaying senescence-associated features and favorable maturation-associated readouts in aged oocytes. These data do not establish physiological granulosa-cell rejuvenation, improved developmental competence, or a DRP1-dependent mechanism. Further studies are required to establish the molecular target of M1 and its effects on fertilization, embryo development, and reproductive outcomes.
The role of mitofusin 2 (Mfn2) in mitochondrial metabolism and neurodegeneration is largely unknown. The current study probes the role of Mfn2 in mitochondrial biogenesis and metabolism in SH-SY5Y neuronal cells using multi-omics strategies. Mfn2 knockdown (KD) by siRNA treatment resulted into diverse proteomic and metabolomic changes. Furthermore, a battery of cellular and molecular analyses associated Mfn2-KD with increased oxidative stress, perturbed mitochondrial membrane potential and reduced mtDNA copy numbers in the neuronal cells. In addition, Mfn2-KD induced dramatic alterations in cell cycle profiles inclusive of proliferation and apoptosis. SWATH-MS-based analysis showed downregulation and upregulation of 11 and 22 differentially expressed proteins (DEPs), respectively, that serve in ribosomal biogenesis, translation, apoptosis, aging, TCA, and OXPHOS metabolic pathways. Among these proteins, TARBP emerged as a hub protein. 1H NMR-based metabolomic analysis showed alterations in 7 metabolites in the Mfn2-KD cells, which were associated with mitochondrial metabolism. Among these metabolites, taurine, a neuromodulator, was significantly downregulated after Mfn2-KD. Interestingly, supplementation of taurine restored the Mfn2-KD-induced deleterious alterations in mitochondrial physiology and cellular metabolomics in the neuronal cells. These results suggest the vital role of Mfn2 in mitochondrial functions in neuronal cells, and taurine emerges as a potential metabolite in Mfn2-linked mitochondrial dysfunction.
Despite therapeutic advances, melanoma remains a lethal malignancy characterised by profound therapeutic resistance. Emerging evidence positions the mitochondrion not as a subordinate organelle but as a central command centre orchestrating the key hallmarks of the disease. This review synthesises the profound dysregulation of the melanoma mitochondrial landscape, detailing the shift from a simple Warburg model to a nuanced understanding of metabolic plasticity, the critical role of organellar dynamics, and the dual function of reactive oxygen species (ROS) as both damaging agents and vital signalling molecules. We explore how this rewired state provides the bioenergetic and biosynthetic currency for proliferation and is essential for the arduous process of metastasis, a journey facilitated by novel mechanisms of intercellular mitochondrial transfer. Critically, the mitochondrion serves as the decisive battleground at the tumour-immune interface. While melanoma cells actively sabotage T-cell mitochondrial fitness to drive immune exhaustion, the metabolic state of the tumour's own mitochondria dictates its immunogenicity and susceptibility to immune attack. This deep mechanistic insight has unveiled a rich portfolio of therapeutic strategies, from direct bioenergetic inhibitors and mitochondria-targeted nanomedicines to innovative modalities such as photodynamic immunotherapy and mitochondrial transplantation, which offer powerful avenues to overcome therapy resistance. Finally, we discuss the burgeoning potential of mitochondrial features as prognostic and predictive biomarkers, arguing that a holistic, systems-level view is essential for paving the way towards a new era of personalised ‘mito-oncology’ to combat this devastating disease.
Growing fibroblasts in medium containing galactose instead of glucose makes cells more dependent on oxidative phosphorylation (OXPHOS) rather than glycolysis. Recently, it has been shown that treatment with nicotinamide adenine dinucleotide (NAD+) improves cell viability of human OXPHOS Complex I-deficient skin fibroblasts in this OXPHOS-reliant condition. To study the effects of NAD+ precursors in this model, we supplemented the cells with trigonelline (TG), nicotinamide (NAM), nicotinamide riboside (NR), nicotinamide mononucleotide (NMN) and found no improvement in cell viability, while supplementation with niacin (NA) did partially. Interestingly, cell viability was improved by addition of the NAD+ building block adenosine monophosphate (AMP). Metabolic profiling showed a decrease in inosine monophosphate (IMP), a purine intermediate, under OXPHOS-reliant condition. Treatment with AMP and adenosine under this condition increased the IMP levels. Among nucleosides, only adenosine and guanosine treatments in OXPHOS-reliant condition improved the patient cell viability. Therefore, we conclude that OXPHOS-reliant condition limited purine nucleotide biosynthesis and salvage pathways, which could be overcome by increasing IMP levels. Together, our results reveal a previously unrecognized role for purine metabolism under OXPHOS-reliant condition, highlighting it as a candidate for therapeutic intervention.
This mini-review and perspective article goes over a brief history of mitochondria and their role in calcium overload and oxidative stress. Altogether, oxidative stress, calcium overload, and mitochondrial dysfunction form a pathophysiological triad, and most of the explanatory power of this triad relies on invoking the mitochondrial permeability transition pore (mPTP) as driving the pathophysiology. As such, many studies claim that calcium overload triggers oxidative stress and acts as the upstream event in mitochondrial dysfunction to explain experimental results. However, recent findings shed new light on this triad and how it affects living tissue. While the mPTP hypothesis has dominated curated explanations, emerging functional and structural data supports a distinct stable overloaded state that better accounts for graded dysfunction in the presence of low intensity chronic oxidative stress. In this stable calcium overload state, mitochondrial dysfunction is evident from the reduced oxidative metabolism impairments accompanying suppressed free radical emission rates, distinct from the effects of opening the mPTP. This refined framework has direct implications for SR/ER–mitochondrial crosstalk in disease and tunes mechanistic models that better align with the available data. While mitochondria absolutely play an important role in various pathologies, they primarily respond to exogenous driving forces that move them into compromised functional states, which in turn amplify cellular disorder. Ideally, this perspective will help refine the intriguing and complex aspects of mitochondrial function in cell death and disease.
