Mitochondrial dynamics: overview of molecular mechanisms. Essays Biochem. 2018;62:341-360. [PMID: 30030364 PMCID: PMC6056715 DOI: 10.1042/ebc20170104]

Targeting OPA1 protein for therapeutic intervention in autosomal dominant optic atrophy: In silico drug discovery

Autosomal dominant hereditary optic atrophy (ADOA) is a prevalent hereditary condition characterized by the gradual and simultaneous deterioration of vision. Mutations in Optic atrophy 1 (OPA1) have been linked to ADOA, the prevailing form of inherited optic neuropathy. However, the current therapeutic options are limited. This study aimed to identify a drug-like molecule that can serve as an activator of the OPA1 GTPase domain, using in silico virtual screening and molecular dynamic simulation pipeline. A ligand-based pharmacophore model was generated to identify the important biological entities in natural compounds, followed by virtual screening pipeline. Total 55,96,00 drug-like compounds were screened and then subsequently proceed for molecular docking, molecular dynamics simulation (200ns), MM-PBSA analysis, and ADMET (Swiss ADME server) studies. Virtual screening revealed the top-ranked compound ZINC000009190697 (-8 kcal/mol). Furthermore, the stability of the top hit compound at the active site of OPA1 was demonstrated using molecular dynamics simulations and MM-PBSA calculations. ADMET analysis assisted in the identification of the top hit compound as possible activators of OPA1 with optimal drug-like properties. These results indicated that there is need of further experimental assessment of the top-hit compound ZINC000009190697 in wet lab to confirm its efficacy as a potential OPA1 activator in both in vitro and in vivo studies.

AMPK-YAP signaling pathway-mediated mitochondrial dynamics and mitophagy participate in the protective effect of silibinin on HaCaT cells under high glucose conditions

UVB irradiation and diabetes lead to skin injury. However, UVB irradiation has rarely been studied in the field of diabetes. Silibinin has a positive therapeutic effect on many diseases. Nevertheless, the inhibitory effects of silibinin on UVB-induced damage to epidermal cells under high glucose (HG) conditions have been infrequently investigated. Consequently, this study examined the protective efficacy and mechanisms of silibinin in mitigating UVB-induced apoptosis in epidermal cells cultured under HG conditions. The effects of combination of HG and UVB on mitochondrial apoptosis and pro-inflammatory factors production in human immortalized keratinocytes (HaCaT) were mitigated by silibinin. Meantime, silibinin reversed the UVB-induced imbalance of fission/fusion in HG-cultured HaCaT cells. Furthermore, UVB exposure increased ROS levels and reduced mitophagy in HaCaT cells under HG conditions; however, these effects were subsequently reversed by silibinin treatment. AMPK preserves energy balance by negatively regulating YAP. Silibinin increased the levels of p-AMPK and cytoplasmic YAP proteins in HaCaT cells subjected to HG and UVB treatment. Moreover, silibinin improved the dysfunction of mitochondrial dynamics, increased mitophagy levels, the viability and the expression of cytoplasmic YAP protein, and these effects were reversed via the application of an AMPK inhibitor (compound C). In summary, silibinin safeguarded epidermal cells from UVB-induced apoptosis under HG conditions by modulating mitochondrial dynamics and mitophagy through the AMPK-YAP signaling pathway.

miR142 silencing alleviates retinal inflammation by impairing mitochondrial function and reprogramming metabolism of CD4+ T cells via targeting MTFR1

BACKGROUND

Autoimmune uveitis is a sight-threatening inflammatory disease of the retina. MicroRNA-142 (miR-142) has been implicated in its pathogenesis. This study aimed to elucidate the role of miR-142 in uveitis and its underlying mechanisms.

METHODS

The expression of miR-142-3p was analyzed in peripheral blood mononuclear cells from uveitis patients and in experimental autoimmune uveitis (EAU) models. With EAU induction for 14 days, clinical and histopathological scores were graded to evaluate the retinal inflammation. To investigate the effects of miR-142 deficiency on uveitis development, the miR-142 knockout (miR-142-/-) mouse model was used. The miR-142-/- T cell phenotype and function were characterized using flow cytometry and single-cell sequencing for both in vivo and in vitro experiments. The Seahorse Analyzer, mitochondrial staining and electron microscope analysis were conducted to reveal the mitochondrial function and morphology. And then Luciferase Assays and Western-Blot analysis were used to explore the target of miR-142.

RESULTS

We found that miR-142-3p was significantly up-regulated in uveitis and that its deletion in mice prevented EAU development. The T cell isolated from miR-142-/- mice lose its uveitogenic nature. T cell lacking miR-142 exhibited reduced numbers and attenuated pathogenicity in uveitis, characterized by decreased proliferation, increased apoptosis, and abnormal differentiation. Single-cell sequencing, energy metabolism analysis and flow cytometry analysis unveiled metabolic reprogramming in miR-142-/- T cells, with a distinct shift toward glycolysis and restrained oxidative phosphorylation. Further investigation revealed mitochondrial fission regulator 1 (MTFR1) as a direct target of miR-142. The over-expressed protein of MTFR1 in CD4+ T cells was found in miR-142-/- mice.

CONCLUSIONS

Our findings highlight the indispensable role of miR-142 in maintaining T cell mitochondrial function. By modulating MTFR1, miR-142 orchestrates mitochondrial homeostasis, metabolic alterations, apoptosis susceptibility, and proliferation capacity in T cells, thereby influencing susceptibility to autoimmune uveitis.

A dynamin-like protein in Plasmodium falciparum plays an essential role in parasite growth, mitochondrial development and homeostasis during asexual blood stages

Malaria parasites harbour a single mitochondrion, and its proper segregation during parasite multiplication is crucial for the propagation of the parasite within the host. Mitochondrial division machinery consists of several proteins that associate with the mitochondrial membrane during segregation. Here, we have identified a dynamin-like protein in P. falciparum, PfDyn2, and deciphered its role in mitochondrial growth and homeostasis. A GFP targeting approach combined with high-resolution microscopy studies showed that the PfDyn2 associates with the mitochondrial membrane at specific sites during mitochondrial division. The C-terminal degradation tag mediated inducible knock-down (iKD) of PfDyn2 significantly inhibited parasite growth. PfDyn2-iKD hindered mitochondrial development and functioning, decreased mtDNA replication, and induced mitochondrial oxidative stress, ultimately causing parasite death. Regulated overexpression of a phosphorylation mutant of PfDyn2 (Ser-612-Ala) did not affect the recruitment of PfDyn2 on the mitochondria; normal mitochondrial division and parasite growth showed that phosphorylation/dephosphorylation of this conserved serine residue (Ser612) may not be responsible for regulating recruitment of PfDyn2 to the mitochondrion. Overall, we show the essential role of PfDyn2 in mitochondrial development and maintaining its homeostasis during the asexual cycle of the parasite.

Donafenib Induces Mitochondrial Dysfunction in Liver Cancer Cells via DRP1

Hepatocellular carcinoma (HCC) represents a significant global health challenge, characterized by a high incidence rate. Mitochondria have emerged as an important therapeutic target for HCC. Donafenib, a multi-receptor tyrosine kinase inhibitor, has been approved for the treatment of advanced HCC. However, the underlying mechanisms remain to be elucidated. In this study, we aim to investigate the effects of Donafenib on mitochondrial function in HCC cells. Firstly, we show that Donafenib induces mitochondrial oxidative stress in SNU-449 liver cancer cells by increasing mitochondrial ROS while reducing glutathione peroxidase (GPx) activity and the expression of Mn-SOD. We also demonstrate that Donafenib decreases mitochondrial membrane potential (MMP) and induces the opening of the mitochondrial permeability transition pore (mPTP). Furthermore, Donafenib reduces mitochondrial respiratory rate, COX IV activity, and ATP production. Notably, Donafenib induces mitochondrial fragmentation and reduces mitochondrial length by increasing the expression of DRP1, without affecting Mfn1 or Mfn2. Silencing of DRP1 protects against mitochondrial dysfunction induced by Donafenib, indicating that DRP1 plays a key role in mediating Donafenib's effects on mitochondrial function in HCC cells.

Disruption of Mitochondrial Quality Control in Inherited Metabolic Disorders

Inherited metabolic disorders (IMDs) are genetic disorders often characterized by the accumulation of toxic metabolites in patient tissues and bodily fluids. Although the pathophysiologic effect of these metabolites and their direct effect on cellular function is not yet established for many of these disorders, animal and cellular studies have shown that mitochondrial bioenergetic dysfunction with impairment of citric acid cycle activity and respiratory chain, along with secondary damage induced by oxidative stress are prominent in some. Mitochondrial quality control, requiring the coordination of multiple mechanisms such as mitochondrial biogenesis, dynamics, and mitophagy, is responsible for the correction of such defects. For inborn errors of enzymes located in the mitochondria, secondary abnormalities in quality control this organelle could play a role in their pathophysiology. This review summarizes preclinical data (animal models and patient-derived cells) on mitochondrial quality control disturbances in selected IMDs.

Role of Mitochondrial Dysfunctions in Neurodegenerative Disorders: Advances in Mitochondrial Biology

Mitochondria, essential organelles responsible for cellular energy production, emerge as a key factor in the pathogenesis of neurodegenerative disorders. This review explores advancements in mitochondrial biology studies that highlight the pivotal connection between mitochondrial dysfunctions and neurological conditions such as Alzheimer's, Parkinson's, Huntington's, ischemic stroke, and vascular dementia. Mitochondrial DNA mutations, impaired dynamics, and disruptions in the ETC contribute to compromised energy production and heightened oxidative stress. These factors, in turn, lead to neuronal damage and cell death. Recent research has unveiled potential therapeutic strategies targeting mitochondrial dysfunction, including mitochondria targeted therapies and antioxidants. Furthermore, the identification of reliable biomarkers for assessing mitochondrial dysfunction opens new avenues for early diagnosis and monitoring of disease progression. By delving into these advancements, this review underscores the significance of understanding mitochondrial biology in unraveling the mechanisms underlying neurodegenerative disorders. It lays the groundwork for developing targeted treatments to combat these devastating neurological conditions.

α‑ketoglutarate protects against septic cardiomyopathy by improving mitochondrial mitophagy and fission

Septic cardiomyopathy is a considerable complication in sepsis, which has high mortality rates and an incompletely understood pathophysiology, which hinders the development of effective treatments. α‑ketoglutarate (AKG), a component of the tricarboxylic acid cycle, serves a role in cellular metabolic regulation. The present study delved into the therapeutic potential and underlying mechanisms of AKG in ameliorating septic cardiomyopathy. A mouse model of sepsis was generated and treated with AKG via the drinking water. Cardiac function was assessed using echocardiography, while the mitochondrial ultrastructure was examined using transmission electron microscopy. Additionally, in vitro, rat neonatal ventricular myocytes were treated with lipopolysaccharide (LPS) as a model of sepsis and then treated with AKG. Mitochondrial function was evaluated via ATP production and Seahorse assays. Additionally, the levels of reactive oxygen species were determined using dihydroethidium and chloromethyl derivative CM‑H2DCFDA staining, apoptosis was assessed using a TUNEL assay, and the expression levels of mitochondria‑associated proteins were analyzed by western blotting. Mice subjected to LPS treatment exhibited compromised cardiac function, reflected by elevated levels of atrial natriuretic peptide, B‑type natriuretic peptide and β‑myosin heavy chain. These mice also exhibited pronounced mitochondrial morphological disruptions and dysfunction in myocardial tissues; treatment with AKG ameliorated these changes. AKG restored cardiac function, reduced mitochondrial damage and corrected mitochondrial dysfunction. This was achieved primarily through increasing mitophagy and mitochondrial fission. In vitro, AKG reversed LPS‑induced cardiomyocyte apoptosis and dysregulation of mitochondrial energy metabolism by increasing mitophagy and fission. These results revealed that AKG administration mitigated cardiac dysfunction in septic cardiomyopathy by promoting the clearance of damaged mitochondria by increasing mitophagy and fission, underscoring its therapeutic potential in this context.

Formin INF2 supplementation alleviates cytoskeleton-based mitochondria defects for oocyte quality under obesity

Obesity is one main cause of reproductive disorders in female, and oocytes show meiotic maturation defects under obesity, which leads to infertility. However, the molecular characterization for the obese oocytes remains largely unclear. Inverted-formin 2 (INF2) is a formin family member which is involved in actin-based multiple cellular events including vesicle transport and oxidative stress-induced apoptosis. In present study, we reported that INF2 deficiency linked with declined oocyte quality of obesity. Our results showed that INF2 expression decreased in the oocytes of obese mice. INF2 deficiency caused the failure of polar body extrusion and induced large polar bodies. We showed that INF2 depletion disturbed mitochondrial distribution and function, which might be due to the association with mitochondria fission factor DRP1. INF2 co-localized with cytoplasmic actin and its depletion reduced actin polymerization, which further caused the failure of spindle migration in both mouse and porcine oocytes. In addition, we also found that INF2 interacted with HDAC6 and further affected tubulin acetylation for microtubule stability, which disturbed mitochondrial transport. Exogenous INF2 mRNA supplement rescued the meiotic maturation defects of oocytes from obese mice. Thus, our study demonstrated that INF2 is responsible for both mouse and porcine oocyte maturation through its regulation on actin polymerization and tubulin acetylation for mitochondrial function, and its deficiency might be one cause for obesity-induced oocyte defects.

NSD1 mutation status determines metabolic inhibitor sensitivity in head and neck squamous cell carcinomas by regulating mitochondrial respiration

Head and neck squamous cell carcinomas (HNSCCs) are the most common malignant tumors in the head and neck region, characterized by a high recurrence rate and early metastasis. Despite advances in treatment, patient outcomes and prognosis remain poor, highlighting the urgent need for new therapeutic strategies. Recent research has increasingly focused on targeting glucose metabolism as a therapeutic strategy for cancer, revealing multiple promising targets and potential drugs. However, the metabolic heterogeneity among tumors leads to variable sensitivity to metabolic inhibitors in different patients, limiting their clinical utility. In this study, we employed bioinformatics analysis, cell experiments, animal models, and multi-omics approaches to reveal differences in glucose metabolism phenotypes among HNSCC patients and elucidated the underlying molecular mechanisms driving these differences. Our findings showed that NSD1 mutation status affects the glucose metabolism phenotype in HNSCC, with NSD1 wild-type HNSCC exhibiting higher mitochondrial respiration and NSD1 mutant HNSCC showing weaker mitochondrial respiration but enhanced glycolysis. We further demonstrated that NSD1 regulates mitochondrial respiration in HNSCC via epigenetic modulation of the TGFB2/PPARGC1A signaling axis. Additionally, we found that NSD1 wild-type HNSCC is more sensitive to mitochondrial respiration inhibitors, whereas NSD1 mutant HNSCC shows increased sensitivity to glycolysis inhibitors. In summary, we found that NSD1 can epigenetically regulate the TGFB2/PPARGC1A axis to modulate mitochondrial respiration and sensitivity to metabolic inhibitors in HNSCC. These findings suggest a novel strategy for selecting metabolic inhibitors for HNSCC based on the NSD1 gene status of patients. © 2025 The Pathological Society of Great Britain and Ireland.

Upregulations of SNAT2 and GLS-1 Are Key Osmoregulatory Responses of Human Corneal Epithelial Cells to Hyperosmotic Stress

Dry eye syndrome (DES) affects millions of people worldwide. However, as the cellular responses of the corneal epithelium under hyperosmotic stress remain unclear, this study investigated the proteomic changes between human corneal epithelial cells (HCECs) cultured with isosmotic and hyperosmotic media. Under hyperosmotic stress, HCECs increased expressions of sodium-coupled neutral amino acid transporter (SNAT2), glutaminase (GLS-1), and a few isoforms of heat shock protein and aldo-keto reductase family 1. The expressions of SNAT2 and GLS-1 were increased after 6 h of exposure to hyperosmotic stress but not by glutamine deprivation. The hyperosmotic stress increased intracellular levels of glutamine, mitochondrial superoxide, and mitochondrial membrane potential and induced mitochondrial fission in HCECs. Thus, the intracellular level of glutamine was elevated in the hyperosmotic stressed HCECs via the upregulation of SNAT2. Glutamine can act as an osmolyte to regulate the osmolarity of HCECs or be converted to glutamate by GLS-1 for the tricarboxylic acid cycle and oxidative phosphorylation to maintain ATP production under the hyperosmotic stress-induced mitochondrial fission. Thus, the increases in the expressions of SNAT2 and GLS-1 are key osmoregulations in HCECs upon the hyperosmotic stress and may act as corneal biomarkers for monitoring DES progression.

Parkin mediates the mitochondrial dysfunction through mRpL18

Loss of function of parkin leads to the mitochondrial dysfunction, which is closely related to Parkinson's disease. However, the in vivo mechanism is far from clear. One of the dogmas is that impaired Parkin causes dysfunction of mitophagy mediated by Pink1-Parkin axis. The other is that impaired Parkin causes Mfn accumulation which leads to mitochondrial dysfunction. Surprisingly, in Drosophila muscles, as reported, the first dogma is not applicable; for the second dogma, our study suggests that Parkin mediates the mitochondrial dysfunction through modulating mitochondrial morphology, which is determined by synergy of both Marf and mitochondrial protein mRpL18 got from our genome-wide screen, whose RNAi rescues parkin RNAi phenotype. Mechanistically, we found that impaired Parkin upregulated both the transcription and protein levels of mRpL18 dependent on its E3 ligase activity, causing the mRpL18 accumulation outside mitochondria. Consequently, cytosolic accumulated mRpL18 competitively bound Drp1, leading to the reduction of the binding of Drp1 to its receptor Fis1, which finally inhibited the mitochondrial fission and tipped the balance to mitochondrial hyperfusion, thereby affected the mitochondrial function. Taken together, our study suggests that impaired Parkin causes mitochondrial hyperfusion due to two reasons: (1) Parkin defect impairs Pink1-Parkin axis-mediated Marf degradation, which promotes mitochondrial fusion; (2) Parkin defect causes mRpL18 accumulation, which inhibits Drp1/Fis1-mediated mitochondrial fission. These two ways function together to drive Parkin-mediated mitochondrial hyperfusion. Therefore, knockdown of either marf or mRpL18 can prevent mitochondrial hyperfusion, leading to the rescue of Parkin defect-triggered fly wing phenotypes. Overall, our study unveils a new facet of how Parkin regulates mitochondrial morphology to affect mitochondrial function, which provides new insights for the understanding and treatment of Parkinson's disease.

What do You Need to Know after Diabetes and before Diabetic Retinopathy?

Diabetic retinopathy (DR) is a leading cause of vision impairment and blindness among individuals with diabetes mellitus. Current clinical diagnostic criteria mainly base on visible vascular structure changes, which are insufficient to identify diabetic patients without clinical DR (NDR) but with dysfunctional retinopathy. This review focuses on retinal endothelial cells (RECs), the first cells to sense and respond to elevated blood glucose. As blood glucose rises, RECs undergo compensatory and transitional phases, and the correspondingly altered molecules are likely to become biomarkers and targets for early prediction and treatment of NDR with dysfunctional retinopathy. This article elaborated the possible pathophysiological processes focusing on RECs and summarized recently published and reliable biomarkers for early screening and emerging intervention strategies for NDR patients with dysfunctional retinopathy. Additionally, references for clinical medication selection and lifestyle recommendations for this population are provided. This review aims to deepen the understanding of REC biology and NDR pathophysiology, emphasizes the importance of early detection and intervention, and points out future directions to improve the diagnosis and treatment of NDR with dysfunctional retinopathy and to reduce the occurrence of DR.

Sestrin2 is a central regulator of mitochondrial stress responses in disease and aging

Mitochondria supply most of the energy for cellular functions and coordinate numerous cellular pathways. Their dynamic nature allows them to adjust to stress and cellular metabolic demands, thus ensuring the preservation of cellular homeostasis. Loss of normal mitochondrial function compromises cell survival and has been implicated in the development of many diseases and in aging. Although exposure to continuous or severe stress has adverse effects on cells, mild mitochondrial stress enhances mitochondrial function and potentially extends health span through mitochondrial adaptive responses. Over the past few decades, sestrin2 (SESN2) has emerged as a pivotal regulator of stress responses. For instance, SESN2 responds to genotoxic, oxidative, and metabolic stress, promoting cellular defense against stress-associated damage. Here, we focus on recent findings that establish SESN2 as an orchestrator of mitochondrial stress adaptation, which is supported by its involvement in the integrated stress response, mitochondrial biogenesis, and mitophagy. Additionally, we discuss the integral role of SESN2 in mediating the health benefits of exercise as well as its impact on skeletal muscle, liver and heart injury, and aging.

Artemetin targets the ABCG2/RAB7A axis to inhibit mitochondrial dysfunction in asthma

BACKGROUND

Artemetin, a natural flavonoid, is well-known for its significant anti-inflammatory and antioxidant properties, but its mechanisms in asthma are still unclear.

PURPOSE

This study aims to explore the therapeutic potential of Artemetin in mitigating airway inflammation and mitochondrial dysfunction via ABCG2/RAB7A signaling pathway.

METHODS

An HDM-induced mouse asthma model and HDM-treated BEAS-2B cell model were established, methods utilized included bioinformatics, molecular docking, Drug Affinity Responsive Target Stability (DARTS), and Cellular Thermal Shift Assay (CETSA), flow cytometry, Western blot, co-immunoprecipitation (CO-IP), immunohistochemistry, and immunofluorescence staining.

RESULTS

Artemetin significantly alleviates the proportion of eosinophils and pro-inflammatory cytokines in BALF, IgE levels in serum, airway epithelial mucus secretion, inflammatory cell infiltration and collagen fiber deposition. ABCG2 was identified as a core binding target of Artemetin. When Artemetin was labeled with Biotin, further experiments confirmed its interaction and upregulation of ABCG2. Overexpression of ABCG2 (OV-ABCG2) enhances antioxidant capacity by upregulating Nrf2, HO-1, SOD and CAT, mitigating mitochondrial oxidative stress (mtROS), improving mitochondrial membrane potential (MMP), and reducing DRP1-mediated mitochondrial fission while enhancing MFN2-mediated fusion. Furthermore, ABCG2 was found to interact with and downregulate RAB7A. Both Artemetin and siRNA-RAB7A notably inhibit p-DRP1 and mitochondrial translocation of DRP1, thereby promoting mitochondrial fusion, reducing mtROS and increasing MMP. KEGG pathway enrichment revealed that ABCG2 is closely linked to apoptosis. Artemetin, OV-ABCG2, and RAB7A knockdown all alleviated HDM-induced PANoptosis by decreasing ZBP1, GSDMD, Caspase-8, FADD, BAX and RIPK1 while increasing anti-apoptotic protein Bcl-2.

CONCLUSION

Artemetin significantly improves airway inflammation, oxidative stress, and mitochondrial dysfunction in asthma by modulating the ABCG2/RAB7A axis and PANoptosis. Artemetin presents new possibilities for adjunctive therapy in the management of asthma.

Mitochondrial and peroxisomal fission in cortical neurogenesis

The human brain is unique in its cellular diversity, intricate cytoarchitecture, function, and complex metabolic and bioenergetic demands, for which mitochondria and peroxisomes are essential. Mitochondria are multifunctional organelles that coordinate various signaling pathways central to neurogenesis. The dynamic morphological changes of the mitochondrial network have been linked to the regulation of bioenergetic and metabolic states. Specific protein machinery is dedicated to mitochondrial fission and fusion, allowing organelle distribution during cell division, organelle repair, and adaptation to environmental stimuli (excellent reviews have been published on these topics [Kondadi and Reichert, 2024; Giacomello et al., 2020; Tilokani et al., 2018; Kraus et al., 2021; Navaratnarajah et al., 2021]). In parallel, peroxisomes contain over 50 different enzymes which regulate metabolic functions that are critical for neurogenesis (Berger et al., 2016; Hulshagen et al., 2008). Peroxisomes share many of the components of their fission machinery with the mitochondria and undergo fission to help meet metabolic demands in response to environmental stimuli (Schrader et al., 2016). This review focuses primarily on the machinery involved in mitochondrial and peroxisomal fission. Mitochondrial fission has been identified as a critical determinant of cell fate decisions (Iwata et al., 2023, 2020; Khacho et al., 2016; King et al., 2021; Prigione and Adjaye, 2010; Vantaggiato et al., 2019; Kraus et al., 2021). The connection between alterations in peroxisomal fission and metabolic changes associated with cellular differentiation remains less clear. Here, we provide an overview of the functional and regulatory aspects of the mitochondrial and peroxisomal fission machinery and provide insight into the current mechanistic understanding by which mitochondrial and peroxisomal fission influence neurogenesis.

SIRT3-Mediated Deacetylation of DRP1K711 Prevents Mitochondrial Dysfunction in Parkinson's Disease

Dysregulation of mitochondrial dynamics is a key contributor to the pathogenesis of Parkinson's disease (PD). Aberrant mitochondrial fission induced by dynamin-related protein 1 (DRP1) causes mitochondrial dysfunction in dopaminergic (DA) neurons. However, the mechanism of DRP1 activation and its role in PD progression remain unclear. In this study, Mass spectrometry analysis is performed and identified a significant increased DRP1 acetylation at lysine residue 711 (K711) in the mitochondria under oxidative stress. Enhanced DRP1K711 acetylation facilitated DRP1 oligomerization, thereby exacerbating mitochondrial fragmentation and compromising the mitochondrial function. DRP1K711 acetylation also affects mitochondrial DRP1 recruitment and fission independent of canonical S616 phosphorylation. Further analysis reveals the critical role of sirtuin (SIRT)-3 in deacetylating DRP1K711, thereby regulating mitochondrial dynamics and function. SIRT3 agonists significantly inhibit DRP1K711 acetylation, rescue DA neuronal loss, and improve motor function in a PD mouse model. Conversely, selective knockout of SIRT3 in DA neurons exacerbates DRP1K711 acetylation, leading to increased DA neuronal damage, neuronal death, and worsened motor dysfunction. Notably, this study identifies a novel mechanism involving aberrant SIRT3-mediated DRP1 acetylation at K711 as a key driver of mitochondrial dysfunction and DA neuronal death in PD, revealing a potential target for PD treatment.

Mitochondrial Quality Control in Ovarian Function: From Mechanisms to Therapeutic Strategies

Mitochondrial quality control plays a critical role in cytogenetic development by regulating various cell-death pathways and modulating the release of reactive oxygen species (ROS). Dysregulated mitochondrial quality control can lead to a broad spectrum of diseases, including reproductive disorders, particularly female infertility. Ovarian insufficiency is a significant contributor to female infertility, given its high prevalence, complex pathogenesis, and profound impact on women's health. Understanding the pathogenesis of ovarian insufficiency and devising treatment strategies based on this understanding are crucial. Oocytes and granulosa cells (GCs) are the primary ovarian cell types, with GCs regulated by oocytes, fulfilling their specific energy requirements prior to ovulation. Dysregulation of mitochondrial quality control through gene knockout or external stimuli can precipitate apoptosis, inflammatory responses, or ferroptosis in both oocytes and GCs, exacerbating ovarian insufficiency. This review aimed to delineate the regulatory mechanisms of mitochondrial quality control in GCs and oocytes during ovarian development. This study highlights the adverse consequences of dysregulated mitochondrial quality control on GCs and oocyte development and proposes therapeutic interventions for ovarian insufficiency based on mitochondrial quality control. These insights provide a foundation for future clinical approaches for treating ovarian insufficiency.

Naringin prevents the impairment of hepatic mitochondrial function in diabetic rats

We previously demonstrated that naringin (NAR) protects against liver damage in streptozotocin (STZ)-induced diabetes in rats. The aim of this study was to elucidate whether NAR is also able to protect the functioning, biogenesis and dynamics of the liver mitochondria in diabetic rats (DM). The activities of isocitrate dehydrogenase and malate dehydrogenase from the Krebs cycle, complex I-III from electron chain and adenosine triphosphate synthase were decreased in DM rats, effects that were blocked by NAR. The gene expression of mitofusin-2 and GTPase dynamin-related protein 1, markers of mitochondrial fusion and fission, were decreased in DM rats, which was prevented by NAR. Total glutathione was decreased and protein carbonyl contents as well as the activity of the antioxidant enzymes were increased in DM rats. All these changes were blocked by NAR. In conclusion, NAR protects the liver mitochondria from DM rats avoiding changes in the activity of Krebs cycle, the respiratory chain and the oxidative phosphorylation as well as preventing alterations in the fusion-fission processes. These effects are mediated, at least in part, by decreasing oxidative stress and anomalies in the enzymatic antioxidant system. Further studies are necessary to validate efficacy and safety of NAR for human use.

Quitting Your Day Job in Response to Stress: Cell Survival and Cell Death Require Secondary Cytoplasmic Roles of Cyclin C and Med13

Following unfavorable environmental cues, cells reprogram pathways that govern transcription, translation, and protein degradation systems. This reprogramming is essential to restore homeostasis or commit to cell death. This review focuses on the secondary roles of two nuclear transcriptional regulators, cyclin C and Med13, which play key roles in this decision process. Both proteins are members of the Mediator kinase module (MKM) of the Mediator complex, which, under normal physiological conditions, positively and negatively regulates a subset of stress response genes. However, cyclin C and Med13 translocate to the cytoplasm following cell death or cell survival cues, interacting with a host of cell death and cell survival proteins, respectively. In the cytoplasm, cyclin C is required for stress-induced mitochondrial hyperfission and promotes regulated cell death pathways. Cytoplasmic Med13 stimulates the stress-induced assembly of processing bodies (P-bodies) and is required for the autophagic degradation of a subset of P-body assembly factors by cargo hitchhiking autophagy. This review focuses on these secondary, a.k.a. "night jobs" of cyclin C and Med13, outlining the importance of these secondary functions in maintaining cellular homeostasis following stress.

GSNO induced mitochondrial Cx43 nitrosylation in cardiomyocyte differentiation from mouse ES cells in vitro

S-nitrosoglutathione (GSNO), considered vital to S-nitrosylation of proteins, has been found fundamentally important to the cardiomyocytes (CMs) maturation. Our previous studies demonstrated that GSNO treatment significantly enhanced the S-nitrosylation of 104 proteins during the differentiation of mouse embryonic stem cells (ESCs) into CMs. Mitochondrial Cx43 (mtCx43), a membrane protein implicated in the intercellular communication, also plays a pivotal role in CMs regeneration from stem cells. However, the involvement of mtCx43 S-nitrosylation in GSNO-induced myocardial differentiation has not been fully elucidated. In this study, we employed an ESCs-derived CMs differentiation model to elucidate the mechanisms underlying GSNO-induced cardiogenesis. Our findings revealed that GSNO treatment significantly up-regulated mitochondrial transmembrane potential, ATP production, reactive oxygen species (ROS) levels, respiratory chain complex Ι activity and mtCx43 hemichannel permeability in embryoid bodies (EBs). Furthermore, S-nitrosylation of mtCx43 was markedly enhanced in differentiating EBs after GSNO treatment. Overexpression of mtCx43 further amplified the pro-mitochondrial maturation effects of GSNO, whereas overexpression of a mutant form, mtCx43C271A attenuated this effect. To investigate the functional role of mtCx43 hemichannels, we pretreated EBs with Gap19, a specific mtCx43 hemichannel blocker, followed by GSNO administration. Gap19 significantly reduced in mitofusin 2 (Mfn2) expression, thereby impairing mitochondrial maturation and function. In addition, Gap19 treatment abrogated the pro-cardiogenic effects of mtCx43 S-nitrosylation. Furthermore, we demonstrated that mtCx43 S-nitrosylation-induced cardiac differentiation was dependent on mitochondrial Ca2+ uptake. In conclusion, GSNO-induced S-nitrosylation of mtCx43 enhances mitochondrial function in EBs by promoting the opening of mtCx43 hemichannels, thus facilitating the targeted differentiation of ESCs into CMs. These findings provide novel insights into the role of mtCx43 S-nitrosylation in mitochondrial regulation and cardiac lineage commitment.

Mitochondrial fission regulates midgut muscle assembly and tick feeding capacity

Ticks ingest over 100 times their body weight in blood. As the primary tissue for blood storage and digestion, the tick midgut's regulation in response to this substantial blood volume remains unclear. Here, we show that blood intake triggers stem cell proliferation and mitochondrial fission in the midgut of Haemaphysalis longicornis. While inhibiting stem cell proliferation does not impact feeding behavior, disruption of mitochondrial fission impairs tick feeding capacity. Mitochondrial fission mediated by dynamin 2 (DNM2) regulates ATP generation, which in turn influences the expression of the tropomyosin-anchoring subunit troponin T (TNT). Knockdown of TNT disrupts muscle fiber assembly, hindering midgut enlargement and contraction, thereby preventing blood ingestion. These findings underscore the indispensable role of musculature in facilitating midgut expansion during feeding in ticks.

Postmortem mitochondrial membrane potential dynamics as a temperature-independent biomarker for early postmortem interval estimation

BACKGROUND

Accurate determination of postmortem interval (PMI) and cause of death (COD) is a critical challenge in forensic pathology, with significant implications for criminal investigations. Traditional PMI estimation methods are based on macroscopic changes and are influenced by environmental factors and investigator subjectivity. Recent advances in molecular biology have shown that certain cellular structures, such as mitochondria, retain functionality after death, making them potential biomarkers for forensic assessment. As mitochondria play a central role in cellular metabolism and respond dynamically to post-mortem hypoxia, investigation of mitochondrial membrane potential (ΔΨm) may provide a quantifiable and objective method for estimating PMI.

RESULTS

We successfully isolated mitochondria from post-mortem tissues and cultured cells, confirming their purity and membrane integrity. Regression analysis showed a strong linear correlation between ΔΨm and PMI in brain, myocardium and skeletal muscle within the first 15-18 h postmortem, with skeletal muscle showing the highest correlation coefficient. ΔΨm values remained stable at different temperatures, suggesting that it is a robust biomarker for estimating PMI. In vitro experiments under hypoxic conditions revealed a transient increase in ΔΨm at 24 h, accompanied by ATP depletion, ROS accumulation and shifts in mitochondrial fission and fusion dynamics, indicating mitochondrial adaptation to oxygen deprivation.

CONCLUSIONS

These findings highlight ΔΨm as a promising temperature stable biomarker for early assessment of PMI. The observed mitochondrial adaptations suggest that ΔΨm-based models may improve forensic accuracy and provide insights into postmortem metabolic processes. Further validation with human postmortem samples is essential to refine these models and explore their applicability to COD determination.

Correlation of organelle interactions in the development of non-alcoholic fatty liver disease

Organelles, despite having distinct functions, interact with each other. Interactions between organelles typically occur at membrane contact sites (MCSs) to maintain cellular homeostasis, allowing the exchange of metabolites and other pieces of information required for normal cellular physiology. Imbalances in organelle interactions may lead to various pathological processes. Increasing evidence suggests that abnormalorganelle interactions contribute to the pathogenesis of non-alcoholic fatty liver disease (NAFLD). However, the key role of organelle interactions in NAFLD has not been fully evaluated and researched. In this review, we summarize the role of organelle interactions in NAFLD and emphasize their correlation with cellular calcium homeostasis, lipid transport, and mitochondrial dynamics.

Fibroblast growth factor 8 (FGF8) induces mitochondrial remodeling in chondrocytes via ERK/AMPK signaling pathway

Osteoarthritis (OA) is a disease characterized by articular cartilage degeneration, and its pathogenic mechanisms are associated with mitochondrial homeostasis disorders. Fibroblast growth factor 8 (FGF8) is a multipotent protein ligand which is upregulated in OA cartilage. However, the molecular mechanisms by which FGF8 regulates mitochondria in chondrocytes are not yet fully understood. Here, we treated chondrocytes with FGF8 and detected the effects of FGF8 on mitochondrial morphology in the cytoplasm using transmission electron and confocal laser scanning microscopy. ATP levels were measured to determine the cellular energy status. Western blotting and immunofluorescence staining experiments were employed to detect the fusion-fission proteins mitofusin 1 (MFN1), mitofusin 2 (MFN2), optic atrophy 1 (OPA1), dynamin-related protein 1 (DRP1), mitochondrial fission 1 protein (FIS1), and related signaling pathways. The FGF receptor (FGFR) inhibitor, AZD4547, and the ERK inhibitor, U0126, were used to verify the specific effects of the FGFR and ERK pathways. We found that FGF8 regulated mitochondrial morphology and dynamics in chondrocytes by inducing mitochondrial elongation. While it upregulated fusion proteins MFN1, MFN2, and OPA1, FGF8 downregulated fission proteins DRP1 and FIS1. ERK and AMPK pathways were activated in chondrocytes after FGF8 treatment. In contrast, both AZD4547 and U0126 inhibitors abolished mitochondrial elongation as well as the alteration of fusion-fission proteins induced by FGF8, and U0126 also inhibited the FGF8-triggered activation of AMPK. This study is the first to reveal that FGF8 remodels mitochondria through ERK/AMPK signaling in chondrocytes, offering novel insights into the potential role of FGF8 in OA.

Mitofusin-Mediated Mitochondrial Fusion Inhibits Pseudorabies Virus Infection in Porcine Cells

Background: Mitochondria are highly dynamic organelles that undergo fusion/fission dynamics, and emerging evidence has established that mitochondrial dynamics plays a crucial regulatory role in the process of viral infection. Nevertheless, the function of mitochondria dynamics during pseudorabies (PRV) infection remains uncertain. Methods: Our investigation commenced with examining PRV-induced alterations in mitochondrial dynamics, focusing on morphological changes and the expression levels of fusion/fission proteins. We then restored mitochondrial dynamics through Mfn1 (Mitofusin 1)/Mfn2 (Mitofusin 2) overexpression and mdivi-1 (mitochondrial division inhibitor-1) treatment to assess their impact on PRV replication and mitochondrial damage. Results: We found a downregulation of the mitochondrial fusion proteins Mfn1, Mfn2, and OPA1 (optic atrophy 1), along with the activation of the fission protein Drp-1 (dynamin-related protein 1) upon PRV infection. Restoring the function of mitochondrial fusion inhibited PRV infection. Furthermore, elevated mitochondrial membrane potential (MMP), decreased reactive oxygen species (ROS) levels, and an increased mitochondrial number were observed after overexpressing Mfns or treatment with mdivi-1. Conclusions: PRV infection impairs mitochondrial dynamics by altering mitochondrial fusion and fission proteins, and the promotion of Mfn-mediated mitochondrial fusion inhibits PRV replication.

Regulating Sirtuin 3-mediated mitochondrial dynamics through vanillic acid improves muscle atrophy in cancer-induced cachexia

Cancer cachexia is a cancer-associated disease characterized by gradual body weight loss due to pathologic muscle and fat loss, but effective treatments are still lacking. Here, we investigate the possible effect of vanillic acid (VA), known for its antioxidant, anti-inflammatory, and anti-obesity effects, on mitochondria-mediated improvement of cancer cachexia. We utilized cachexia-like models using CT26 colon cancer and dexamethasone. VA improved representative parameters of cancer cachexia including body weight loss and increased serum intereukin-6 levels. VA also attenuated muscle loss in the tibialis anterior and gastrocnemius muscles, inhibited proteolytic markers including muscle RING-finger protein-1 (MURF1) and muscle atrophy F-box (MAFbx) and improved mitochondrial function through alteration of sirtuins 3 (SIRT3) and mitofusin 1 (MFN1). Importantly, silencing the SIRT3 gene abolished the effect of VA, indicating that SIRT3 is important in the mechanism of action of VA. Overall, we suggest using VA as a novel therapeutic agent that can fundamentally treat and recover muscle atrophy in cancer cachexia patients.

Galectin-8 drives ERK-dependent mitochondrial fragmentation, perinuclear relocation and mitophagy, with metabolic adaptations for cell proliferation

Mitochondria adapt to the cell proliferative demands induced by growth factors through dynamic changes in morphology, distribution, and metabolic activity. Galectin-8 (Gal-8), a carbohydrate-binding protein that promotes cell proliferation by transactivating the EGFR-ERK signaling pathway, is overexpressed in several cancers. However, its impact on mitochondrial dynamics during cell proliferation remains unknown. Using MDCK and RPTEC kidney epithelial cells, we demonstrate that Gal-8 induces mitochondrial fragmentation and perinuclear redistribution. Additionally, mitochondria adopt donut-shaped morphologies, and live-cell imaging with two Keima-based reporters demonstrates Gal-8-induced mitophagy. ERK signaling inhibition abrogates all these Gal-8-induced mitochondrial changes and cell proliferation. Studies with established mutant versions of Gal-8 and CHO cells reveal that mitochondrial changes and proliferative response require interactions between the N-terminal carbohydrate recognition domain of Gal-8 and α-2,3-sialylated N-glycans at the cell surface. DRP1, a key regulator of mitochondrial fission, becomes phosphorylated in MDCK cells or overexpressed in RPTEC cells in an ERK-dependent manner, mediating mitochondrial fragmentation and perinuclear redistribution. Bafilomycin A abrogates Gal-8-induced cell proliferation, suggesting that mitophagy serves as an adaptation to cell proliferation demands. Functional analysis under Gal-8 stimulation shows that mitochondria maintain an active electron transport chain, partially uncoupled from ATP synthesis, and an increased membrane potential, indicative of healthy mitochondria. Meanwhile, the cells exhibit increased extracellular acidification rate and lactate production via aerobic glycolysis, a hallmark of an active proliferative state. Our findings integrate mitochondrial dynamics with metabolic adaptations during Gal-8-induced cell proliferation, with potential implications for physiology, disease, and therapeutic strategies.

Novel biomarkers of mitochondrial dysfunction in Long COVID patients

Coronavirus disease 2019 (COVID-19) can lead to severe acute respiratory syndrome, and while most individuals recover within weeks, approximately 30-40% experience persistent symptoms collectively known as Long COVID, post-COVID-19 syndrome, or post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (PASC). These enduring symptoms, including fatigue, respiratory difficulties, body pain, short-term memory loss, concentration issues, and sleep disturbances, can persist for months. According to recent studies, SARS-CoV-2 infection causes prolonged disruptions in mitochondrial function, significantly altering cellular energy metabolism. Our research employed transmission electron microscopy to reveal distinct mitochondrial structural abnormalities in Long COVID patients, notably including significant swelling, disrupted cristae, and an overall irregular morphology, which collectively indicates severe mitochondrial distress. We noted increased levels of superoxide dismutase 1 which signals oxidative stress and elevated autophagy-related 4B cysteine peptidase levels, indicating disruptions in mitophagy. Importantly, our analysis also identified reduced levels of circulating cell-free mitochondrial DNA (ccf-mtDNA) in these patients, serving as a novel biomarker for the condition. These findings underscore the crucial role of persistent mitochondrial dysfunction in the pathogenesis of Long COVID. Further exploration of the cellular and molecular mechanisms underlying post-viral mitochondrial dysfunction is critical, particularly to understand the roles of autoimmune reactions and the reactivation of latent viruses in perpetuating these conditions. This comprehensive understanding could pave the way for targeted therapeutic interventions designed to alleviate the chronic impacts of Long COVID. By utilizing circulating ccf-mtDNA and other novel mitochondrial biomarkers, we can enhance our diagnostic capabilities and improve the management of this complex syndrome.

HBimmCue: A Versatile Fluorescent Probe for Multi-Scale Imaging of Lipid Polarity and Membrane Order in Inner Mitochondrial Membrane

Mitochondrial membrane environmental dynamics are crucial for understanding function, yet high-resolution observation remains challenging. Here, HBimmCue is introduced as a fluorescent probe localized to inner mitochondrial membrane (IMM) that reports lipid polarity and membrane order changes, which correlate with cellular respiration levels. Using HBimmCue and fluorescence lifetime imaging microscopy (FLIM), IMM lipid heterogeneity is uncovered across scales, from nanoscale structures within individual mitochondria to mouse pre-implantation embryos. At the sub-organelle level, stimulated emission depletion (STED)-FLIM imaging highlights nanoscale polarity variations within the IMM. At the sub-cellular and cellular level, reduced IMM lipid polarity is observed in damaged mitochondria marked for lysosomal degradation and distinct IMM lipid distributions are identified in neurons and disease models. Additionally, metabolic dysfunction associated with oocytes aging and metabolic reprogramming from zygote to blastocyst is detected. Together, the work demonstrates the broad applicability of HBimmCue, offering a new paradigm for investigating lipid polarity and respiration level at multiple scales.

Pharmacological modulation of mitochondrial function as novel strategies for treating intestinal inflammatory diseases and colorectal cancer

Inflammatory bowel disease (IBD) is a chronic and recurrent intestinal disease, and has become a major global health issue. Individuals with IBD face an elevated risk of developing colorectal cancer (CRC), and recent studies have indicated that mitochondrial dysfunction plays a pivotal role in the pathogenesis of both IBD and CRC. This review covers the pathogenesis of IBD and CRC, focusing on mitochondrial dysfunction, and explores pharmacological targets and strategies for addressing both conditions by modulating mitochondrial function. Additionally, recent advancements in the pharmacological modulation of mitochondrial dysfunction for treating IBD and CRC, encompassing mitochondrial damage, release of mitochondrial DNA (mtDNA), and impairment of mitophagy, are thoroughly summarized. The review also provides a systematic overview of natural compounds (such as flavonoids, alkaloids, and diterpenoids), Chinese medicines, and intestinal microbiota, which can alleviate IBD and attenuate the progression of CRC by modulating mitochondrial function. In the future, it will be imperative to develop more practical methodologies for real-time monitoring and accurate detection of mitochondrial function, which will greatly aid scientists in identifying more effective agents for treating IBD and CRC through modulation of mitochondrial function.

Nellie: automated organelle segmentation, tracking and hierarchical feature extraction in 2D/3D live-cell microscopy

Cellular organelles undergo constant morphological changes and dynamic interactions that are fundamental to cell homeostasis, stress responses and disease progression. Despite their importance, quantifying organelle morphology and motility remains challenging due to their complex architectures, rapid movements and the technical limitations of existing analysis tools. Here we introduce Nellie, an automated and unbiased pipeline for segmentation, tracking and feature extraction of diverse intracellular structures. Nellie adapts to image metadata and employs hierarchical segmentation to resolve sub-organellar regions, while its radius-adaptive pattern matching enables precise motion tracking. Through a user-friendly Napari-based interface, Nellie enables comprehensive organelle analysis without coding expertise. We demonstrate Nellie's versatility by unmixing multiple organelles from single-channel data, quantifying mitochondrial responses to ionomycin via graph autoencoders and characterizing endoplasmic reticulum networks across cell types and time points. This tool addresses a critical need in cell biology by providing accessible, automated analysis of organelle dynamics.

Hydrogen sulfide sustains mitochondria functions via targeting mitochondria fission regulator 1 like protein to restore human cytotrophoblast invasion and migration

Hydrogen sulfide (H2S) is bioactive in mammals. Reduced H2S was observe in pregnancy complications, pre-eclampsia (PE). Our previous data demonstrated that low dose of H2S enhanced cytotrophoblast (CTB) invasion and migration via mitochondria dynamics without knowing the mechanisms. This study was designed to explore the functional regulation of CTB by mitochondrial fission regulator 1 like (MTFR1L) and the mechanisms. By studying human placenta samples and HTR-8/SVneo cell line, MTFR1L was found expressed in CTB. While MTFR1L expression was lower in PE placenta and CTB comparing with Normal pregnancy. Knockdown of MTFR1L decreased CTB invasion and migration, as well as the ATP production, while increased the mitochondria fragmentation, ROS production and mitochondria membrane potential indicating MTFR1L was key regulator of mitochondria. The posttranslational modulation analysis showed enhanced persulfidation of MTFR1L on cystine 222 and 230 by H2S. Mutations of MTFR1LC222/C230 suppressed ATP production, CTB invasion, migration, and increased mitochondria fragmentation, ROS production and mitochondria membrane potential. The present study showed the functional MTFR1L received endogenous CBS/H2S regulation. MTFR1LC222/230 persulfidation by H2S maintained mitochondria morphology and functions thus restored CTB invasion and migration. These findings established a new regulatory pathway for CTB invasion and migration, and provided new targets for PE treatment.

Mitochondrial fission surveillance is coupled to Caenorhabditis elegans DNA and chromosome segregation integrity

Mitochondrial fission and fusion are tightly regulated to specify mitochondrial abundance, localization, and arrangement during cell division as well as in the diverse differentiated cell types and physiological states. However, the regulatory pathways for such mitochondrial dynamics are less explored than the mitochondrial fission and fusion components. Here we report a large-scale screen for genes that regulate mitochondrial fission. Mitochondrial fission defects cause a characteristic uneven fluorescent pattern in embryos carrying mitochondrial stress reporter genes. Using this uneven activation, we performed RNAi screens that identified 3 kinase genes from a ~ 500-kinase library and another 11 genes from 3,300 random genes that function in mitochondrial fission. Many of these identified genes play roles in chromosome segregation. We found that chromosome missegregation and genome instability lead to dysregulation of mitochondrial fission, possibly independent of DRP-1. ATL-1, the C. elegans ATR orthologue, plays a potentially protective role in alleviating the mitochondrial fission defect caused by chromosome missegregation. This establishes a screening paradigm for identifying mitochondrial fission regulators, which reveals the potential role of ATR in surveilling mitochondrial fission to mitigate dysregulation caused by improper chromosome segregation.

Early Life Stress Induces Brain Mitochondrial Dynamics Changes and Sex-Specific Adverse Effects in Adulthood

Early life stress exposure exerts detrimental effects in adulthood and is a risk factor for psychiatric disorders. Studies addressing the molecular mechanisms of early life stress have primarily focused on hormones and stress circuits. However, little is known on how mitochondria and mitochondrial dynamics (i.e., the orchestration of mitochondrial fission, fusion, mitophagy, and biogenesis) modulate early life stress responses. Here, we used a maternal separation with early weaning (MSEW) paradigm to investigate the behavioral and molecular early life stress-elicited effects in male and female C57BL/6 mice in adulthood. We first applied a behavioral test battery to assess MSEW-driven, anxiety-related and stress-coping alterations. We then looked for MSEW-induced, mitochondria-centered changes in cingulate cortex, hippocampus and cerebellum, as well as in plasma by combining protein, mRNA, mitochondrial DNA copy number (mtDNAcn) and metabolomics analyses. We found that MSEW mice are more anxious, show decreased antioxidant capacity in the cingulate cortex and have higher mRNA levels of the fission regulator Fis1 and the mitophagy activator Pink1 in the hippocampus, indicating a shift towards mitochondrial degradation. Hippocampal mRNA level alterations of apoptotic markers further suggest an MSEW-driven activation of apoptosis accompanied by a dysregulation of purine catabolism in the cerebellum in MSEW mice. Sex-specific analysis revealed distinct MSEW-induced changes in male and female mice at the molecular level. Our work reveals a previously unexplored role of mitochondrial dynamics in regulating early life stress effects and highlights a mitochondria-centered dysregulation as a persistent outcome of early life stress in adulthood.

Molybdenum nanodots act as antioxidants for photothermal therapy osteoarthritis

Osteoarthritis (OA) manifests as the degradation of cartilage and remodeling of subchondral bone. Restoring homeostasis within the joint is imperative for alleviating OA symptoms. Current interventions primarily target singular aspects, such as anti-aging, inflammation inhibition, free radical scavenging, and regeneration of cartilage and subchondral bone. Herein, we developed molybdenum nanodots (MNDs) as bionic photothermal nanomaterials to mimic the antioxidant synthase to concurrently protected cartilage and facilitate subchondral bone regeneration. With near-infrared (NIR) irradiation, MNDs effectively eliminate reactive oxygen and nitrogen species (ROS/RNS) from OA chondrocytes, thereby reversed mitochondrial dysfunction, mitigating chondrocyte senescence, and simultaneously suppresses inflammation, hence preserving the inherent homeostasis between cartilage matrix synthesis and degradation while circumventing safety concerns. RNA sequencing of OA chondrocytes treated with MNDs-NIR revealed the reinstatement of chondrocyte functionality, activation of antioxidant enzymes, anti-aging properties, and regulation of inflammation. NIR irradiation induces thermogenesis and synergistically promotes subchondral bone regeneration via MNDs, as validated through histological assessments and microcomputed tomography (Micro-CT) scans. MNDs-NIR effectively attenuate cellular senescence and inhibit inflammation in vivo, while also remodeling mitochondrial dynamics by upregulating fusion proteins and inhibiting fission proteins, thereby regulating the oxidative stress microenvironment. Additionally, MNDs-NIR exhibited remarkable therapeutic effects in alleviating articular cartilage degeneration in an OA mouse model, evidenced by a 1.67-fold reduction in subchondral bone plate thickness, an 88.57 % decrease in OARSI score, a 5.52-fold reduction in MMP13 expression, and a 6.80-fold increase in Col II expression. This novel disease-modifying approach for OA utilizing MNDs-NIR offers insight and a paradigm for improving mitochondrial dysfunction by regulating the accumulation of mitochondrial ROS and ultimately alleviating cellular senescence. Moreover, the dual-pronged therapeutic approach of MNDs-NIR, which addresses both cartilage erosion and subchondral bone lesions in OA, represents a highly promising strategy for managing OA.

Dysfunctional Mitochondria Characterize Amyotrophic Lateral Sclerosis Patients' Cells Carrying the p.G376D TARDBP Pathogenetic Substitution

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease caused by the degeneration of upper and lower motor neurons in the brain, brainstem and spinal cord. About 10% of familial ALS cases are linked to pathogenetic substitution in TARDBP, the gene encoding the TDP-43 protein. A novel rare causative variant in TARDBP (p.G376D) was recently reported in ALS patients. It leads to TDP-43 cytoplasmic mislocalization, increased oxidative stress and reduced cell viability. However, functional studies on the effects of this molecular defect have not yet been carried out. Mitochondria are highly dynamic organelles, and their deregulation has emerged as a key factor in many diseases, among which is ALS. Therefore, this study aimed at determining the impact of this causative variant on mitochondria. In cellular models expressing TDP-43G376D and in fibroblasts derived from patients carrying this molecular defect, we observed alterations of mitochondrial functionality. We demonstrated increased localization of the mutated protein to mitochondria and a reduced abundance of subunits of complex I and complex II of the mitochondrial respiratory chain, associated with a decrease in mitochondrial membrane potential, in cellular respiration and in cytochrome C oxidase (COX) activity. Moreover, ALS cells showed increased mitochondrial fragmentation and reduced abundance of antioxidant enzymes causing increased oxidative stress. These results expand our knowledge about the molecular mechanisms underlying ALS pathogenesis associated with TDP-43 p.G376D and could help to identify new therapeutic strategies to counteract this disease.

Molecular pathways in cardiovascular disease under hypoxia: Mechanisms, biomarkers, and therapeutic targets

Chronic hypoxia is a key factor in the pathogenesis of cardiovascular diseases, including ischemia, heart failure, and hypertension. Under hypoxic conditions, oxygen deficiency disrupts oxidative phosphorylation in mitochondria, impairing ATP production and generating reactive oxygen species (ROS). These reactive species induce mitochondrial dysfunction, leading to oxidative stress, calcium imbalance, and activation of apoptosis pathways. Mitochondrial K-ATP (mitoK-ATP) and mitochondrial permeability transition pore (mPTP) channels are particularly affected, contributing to membrane potential loss, cytochrome C release, and cell death. This review explores the molecular mechanisms underlying hypoxia-induced cardiovascular diseases, with a focus on mitochondrial impairment, ion channel dysfunction, and ROS overproduction. Additionally, we examine hypoxia-inducible factor 1-alpha (HIF-1α) as a biomarker of cellular adaptation and discuss therapeutic strategies targeting mitochondrial function and oxidative stress. Antioxidants and compounds modulating key ion channels, such as K-ATP and mPTP, are highlighted as promising interventions for mitigating hypoxia-induced damage. Furthermore, we emphasize the potential of integrating in vitro, in vivo, and in silico studies to develop novel therapies aimed at preserving mitochondrial integrity and preventing cardiovascular diseases.

ZnT6-mediated Zn2+ redistribution: impact on mitochondrial fission and autophagy in H9c2 cells

Cytosolic free Zn2⁺ level ([Zn2⁺]Cyt) is tightly regulated by Zn2⁺ transporters, under both physiological and pathological conditions. At the cellular level, dysregulated free Zn2⁺ levels have been linked to metabolic and cardiovascular diseases, primarily through their association with various Zn2⁺ transporters. However, the role and localization of ZnT6 in cardiomyocytes remain unclear. Previous studies have shown a significant increase in ZnT6 expression in insulin-resistant cardiomyocytes, suggesting a potential link between ZnT6 dysregulation and cardiac cell dysfunction. Therefore, here, we investigated the impact of ZnT6 overexpression (ZnT6-OE) on cellular Zn2⁺ distribution, mitochondrial dynamics, and autophagy-induced apoptosis in H9c2 cardiomyocytes. Using confocal imaging, biochemical assays, and electron microscopy, we demonstrated the mitochondrial localization of ZnT6 and its role in H9c2 cells. Our findings showed that ZnT6 overexpression led to a significant increase in mitochondrial free Zn2⁺ level ([Zn2⁺]Mit) with a significant reduction in [Zn2⁺]Cyt, which seems to be associated with enhanced numbers of mitochondria and mitochondrial fission process. Specifically, the ZnT6-OE cells exhibited increased dynamin-related protein 1 (DRP1) translocation to mitochondria which is an indication of excessive fission activity. We also determined severe mitochondrial dysfunction in ZnT6-OE cells, such as depolarization in mitochondrial membrane potential, production of excessive reactive oxygen species (ROS), reduced ATP levels, and autophagosome accumulation. Furthermore, these impairments were accompanied by elevated apoptotic markers, indicating autophagy-induced apoptosis. Our findings highlight ZnT6 as a critical regulator of mitochondrial dynamics and function in cardiomyocytes, contributing to disruption Zn2⁺ homeostasis by its overexpression, triggering excessive DRP1-mediated mitochondrial fission and leading to mitochondrial dysfunction, oxidative stress, and apoptotic cell death, suggesting an important impact of ZnT6 dysregulation on cardiomyocyte pathophysiology in metabolic disorders.

Enhanced mitochondrial function and delivery from adipose-derived stem cell spheres via the EZH2-H3K27me3-PPARγ pathway for advanced therapy

BACKGROUND

Microenvironmental alterations induce significant genetic and epigenetic changes in stem cells. Mitochondria, essential for regenerative capabilities, provide the necessary energy for stem cell function. However, the specific roles of histone modifications and mitochondrial dynamics in human adipose-derived stem cells (ASCs) during morphological transformations remain poorly understood. In this study, we aim to elucidate the mechanisms by which ASC sphere formation enhances mitochondrial function, delivery, and rescue efficiency.

METHODS

ASCs were cultured on chitosan nano-deposited surfaces to form 3D spheres. Mitochondrial activity and ATP production were assessed using MitoTracker staining, Seahorse XF analysis, and ATP luminescence assays. Single-cell RNA sequencing, followed by Ingenuity Pathway Analysis (IPA), was conducted to uncover key regulatory pathways, which were validated through molecular techniques. Pathway involvement was confirmed using epigenetic inhibitors or PPARγ-modulating drugs. Mitochondrial structural integrity and delivery efficiency were evaluated after isolation.

RESULTS

Chitosan-induced ASC spheres exhibited unique compact mitochondrial morphology, characterized by condensed cristae, enhanced mitochondrial activity, and increased ATP production through oxidative phosphorylation. High expressions of mitochondrial complex I genes and elevated levels of mitochondrial complex proteins were observed without an increase in reactive oxygen species (ROS). Epigenetic modification of H3K27me3 and PPARγ involvement were discovered and confirmed by inhibiting H3K27me3 with the specific EZH2 inhibitor GSK126 and by adding the PPARγ agonist Rosiglitazone (RSG). Isolated mitochondria from ASC spheres showed improved structural stability and delivery efficiency, suppressed the of inflammatory cytokines in LPS- and TNFα-induced inflamed cells, and rescued cells from damage, thereby enhancing function and promoting recovery.

CONCLUSION

Enhancing mitochondrial ATP production via the EZH2-H3K27me3-PPARγ pathway offers an alternative strategy to conventional cell-based therapies. High-functional mitochondria and delivery efficiency show significant potential for regenerative medicine applications.

Forkhead box O-1 regulates the biological behavior of BMP-2-induced human bone mesenchymal stem cells through mitochondrial dynamics and autophagy

This study explored the mechanism by which forkhead box O-1 (FoxO1) modulates the biological behaviors of bone mesenchymal stem cell (BMSC). Human BMSCs were cultured for seven days in Dulbecco's modified Eagle medium (DMEM) containing bone morphogenetic protein-2 (BMP-2) and treated with a short hairpin-FoxO1 plasmid. The study assessed cell proliferation, migration, apoptosis, adenosine triphosphate (ATP) levels, mitochondrial DNA (mtDNA) levels, membrane potential (MMP), autophagy, and the levels of FoxO1, apoptosis-associated proteins, osteogenic differentiation-associated proteins, mitochondrial fusion and fission proteins, and mitochondrial autophagy-related proteins. The cells were also treated with the mitochondrial fusion activator MASM7 and the mitochondrial autophagy activator carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The study evaluated whether mitochondrial dynamics and autophagy activation could rescue the FoxO1 knockdown-induced changes in BMSC biological behaviors, mitochondrial dynamics, and mitochondrial autophagy. BMP-2-induced BMSCs exhibited upregulated FoxO1 expression, enhanced proliferation and migration, and induced osteogenic differentiation, while FoxO1 knockdown inhibited BMP-2-induced BMSC proliferation, migration and osteogenic differentiation, increased apoptosis, and affected mitochondrial dynamics and autophagy. Promoting mitochondrial fusion partially reversed the regulatory effects of FoxO1 downregulation on mitochondrial autophagy and the inhibitory effects of FoxO1 silencing on BMP-2-induced BMSC biological behaviors. Activated mitochondrial autophagy facilitated the homeostasis of mitochondrial dynamics and partially counteracted the inhibitory effects of FoxO1 knockdown on BMP-2-induced BMSC biological behaviors. In conclusion, FoxO1 regulates mitochondrial dynamics and autophagy to modulate the osteogenic differentiation of BMP-2-induced human BMSCs.

Magnoflorine ameliorates cartilage degradation in osteoarthritis through inhibition of mitochondrial reactive oxygen species-mediated activation of the NLRP3 inflammasome

This study investigated the role of magnoflorine (MAG) on cartilage protection in osteoarthritis. In vitro studies showed that MAG decreased the expression of inflammatory factors and inhibited extracellular matrix degradation in lipopolysaccharide- and ATP-stimulated C28/I2 cells. Importantly, MAG reduced the levels of pyroptosis-related proteins, including NLRP3, ASC, cleaved-caspase 1, GSDMD-N, IL-18, and IL-1β. Mechanistically, MAG reduced mtROS production and inhibited the activation of the NF-κB signaling pathway. In vivo study demonstrated that sodium iodoacetate-induced cartilage degradation and inflammatory factor release were reversed by MAG. Overall, MAG could inhibit mtROS-mediated NLRP3 inflammasome activation by suppressing mitochondrial dysfunction to ameliorate osteoarthritis.

Emerging insights into pulmonary hypertension: the potential role of mitochondrial dysfunction and redox homeostasis

Pulmonary hypertension (PH) is heterogeneous diseases that can lead to death due to progressive right heart failure. Emerging evidence suggests that, in addition to its role in ATP production, changes in mitochondrial play a central role in their pathogenesis, regulating integrated metabolic and signal transduction pathways. This review focuses on the basic principles of mitochondrial redox status in pulmonary vascular and right ventricular disorders, a series of dysfunctional processes including mitochondrial quality control (mitochondrial biogenesis, mitophagy, mitochondrial dynamics, mitochondrial unfolded protein response) and mitochondrial redox homeostasis. In addition, we will summarize how mitochondrial renewal and dynamic changes provide innovative insights for studying and evaluating PH. This will provide us with a clearer understanding of the initial signal transmission of mitochondria in PH, which would further improve our understanding of the pathogenesis of PH.

Mitochondria in cutaneous health, disease, ageing and rejuvenation-the 3PM-guided mitochondria-centric dermatology

Association of both intrinsic and extrinsic risk factors leading to accelerated skin ageing is reflected in excessive ROS production and ir/reversible mitochondrial injury and burnout, as abundantly demonstrated by accumulating research data. Due to the critical role of mitochondrial stress in the pathophysiology of skin ageing and disorders, maintained (primary care) and restored (secondary care) mitochondrial health, rejuvenation and homoeostasis are considered the most effective holistic approach to advance dermatological treatments based on systemic health-supportive and stimulating measures. Per evidence, an effective skin anti-ageing protection, wound healing and scarring quality - all strongly depend on the sustainable mitochondrial functionality and well-balanced homoeostasis. The latter can be objectively measured and, if necessary, restored in a systemic manner by pre- and rehabilitation algorithms tailored to individualised patient profiles. The entire spectrum of corresponding innovations in the area includes natural and systemic skin rejuvenation, aesthetic and reconstructive medicine, sustainable skin protection and targeted treatments of skin disorders. Contextually, mitochondria-centric dermatology is instrumental for advanced 3PM-guided approach which makes a good use of predictive multi-level diagnostics and targeted protection of skin against both - the health-to-disease transition and progression of relevant disorders. Cost-effective targeted protection and new treatment avenues focused on sustainable mitochondrial health and physiologic homoeostasis are proposed in the article including in-depth analysis of patient cases and exemplified 3PM-guided care with detailed mechanisms and corresponding expert recommendations presented.

Proteomic analysis reveals QiShenYiQi Pills ameliorates ischemia-induced heart failure through inhibition of mitochondrial fission

BACKGROUND

QiShenYiQi Pills (QSYQ) has widely used in clinical treatment of cardiovascular diseases; however, the exact mechanism behind its effectiveness still requires further investigation.

PURPOSE

The purpose of the study was to explore the potential mechanism of QSYQ in the treatment of ischemic heart failure from the perspective of proteomics.

METHODS

In vivo, to observe QSYQ actions on the progression of ischemia-induced heart failure, cardiac function and remodeling was analyzed. The heart tissues of mice were used for Tandem Mass Tag (TMT)-based proteomic analysis. Cardiomyocytes were prepared and subjected to oxygen-glucose deprivation injury. QSYQ effects on differential proteins expressions, mitochondrial fission and mitochondrial function were assayed.

RESULTS

QSYQ treatment preserved cardiac function, limited cardiac fibrosis and alleviated cardiomyocyte hypertrophy in post-myocardial ischemia mice. Proteomic analysis revealed that QSYQ-responsive proteins were mainly involved in mitochondrial fission, including mitochondrial calcium uniporter (MCU), membrane associated ring-CH-type finger 5 (MARCHF5), and mitochondrial fission process 1 (MTFP1). Protein-protein interaction analysis revealed that MCU, MARCHF5 and MTFP1 commonly interacted with dynamin-related protein 1 (DRP1). Knockdown of MCU, MARCHF5, or MTFP1 attenuated excessive mitochondrial fission in cardiomyocytes through regulating DRP1 phosphorylation and its mitochondrial translocation. QSYQ decreased the phosphorylation of DRP1 at Ser616 and enhanced its inhibitory phosphorylation at Ser637, as well as mitigating the mitochondrial recruitment and oligomerization of DRP1, through downregulation of these three differential proteins. As a result, QSYQ alleviated aberrant mitochondrial fission, ameliorated mitochondrial dysfunction, and protected cardiomyocytes from ischemic injury.

CONCLUSION

The novelty lies in the proteomics-based investigation of the mechanism of QSYQ, uncovering that QSYQ mitigated ischemia-induced heart failure by suppressing MCU/MARCHF5/MTFP1-DRP1-driven mitochondrial fission.

Labeling and isolating cell specific neuronal mitochondria and their functional analysis in mice post stroke

Dendritic and axonal plasticity, which mediates neurobiological recovery after a stroke, critically depends on the mitochondrial function of neurons. To investigate, in vivo, neuronal mitochondrial function at the stroke recovery stage, we employed Mito-tag mice combined with cerebral cortical infection of AAV9 produced from plasmids carrying Cre-recombinase controlled by two neuronal promoters, synapsin-I (SYN1) and calmodulin-kinase IIa to induce expression of a hemagglutinin (HA)-tagged enhanced green fluorescence protein (EGFP) that localizes to mitochondrial outer membranes of SYN1 positive (SYN+) and CaMKIIa positive (CaMKIIa+) neurons. These mice were then subjected to permanent middle cerebral artery occlusion (MCAO) and sacrificed 14 days post stroke. Neuronal mitochondria were then selectively isolated from the fresh brain tissues excised from the ischemic core (IC), ischemic boundary zone (IBZ), as well as from the homologous contralateral hemisphere (CON) by anti-HA magnetic beads for functional analyses. We found that the bead pulled neuronal specific mitochondria were co-precipitated with GFP and enriched with mitochondrial markers, e.g. voltage-dependent anion channel, cytochrome C, and COX IV, but lacked the Golgi protein RCAS1 as well as endoplasmic reticulum markers: Heme‑oxygenase 1 and Calnexin, indicating that specific neuronal mitochondria have been selectively isolated. Western-blot data showed that oxidative phosphorylation (OXPHOS) components in SYN+ and CAMKII+ neuronal mitochondria were significantly decreased in the IBZ and further decreased in the IC compared to the contralateral tissue, which was associated with the significant reductions of mitochondrial function indicated by oxygen consumption rate (OCR) (p < 0.05, respectively, for both neuron types). These data suggest dysfunction of neuronal mitochondria post stroke is present during the stroke recovery stage. Collectively, for the first time, we demonstrated that using a Mito-tag mouse line combined with AAV9 carrying Cre recombinase approach, neuronal specific mitochondria can be efficiently isolated from the mouse brain to investigate their functional changes post stroke.

OPA1 deficiency induces mitophagy through PINK1/Parkin pathway during bovine oocytes maturation

In vitro embryo production (IVP) technology has been increasingly applied to beef cattle breeding. In vitro maturation (IVM) technology is the basis of IVP. However, the quality of in vitro-generated mature oocytes is still poor. Mitochondria are the energy factories of oocytes, so they are crucial for oocyte quality. OPA1 is a protein located on the mitochondrial inner membrane, and its main function is to mediate mitochondrial inner membrane fusion. This work demonstrated that OPA1 is expressed at different stages of meiosis in bovine oocytes. The inhibition of OPA1 activity resulted in a reduced rate of first polar body excretion from bovine oocytes and disruption of the spindle structure. OPA1 deficiency impacted mitochondria by leading to mitochondrial dysfunction, promoting mitochondrial fission, and inducing mitophagy through the PINK1/Parkin pathway. Taken together, our findings suggest that OPA1 is essential for bovine oocyte maturation and that OPA1 deficiency leads to mitochondrial dysfunction and promotes mitochondrial fission as well as mitophagy.

Mitochondrial fission and fusion in neurodegenerative diseases:Ca2+ signalling

Neurodegenerative diseases (NDs) are a group of disorders characterized by the progressive loss of neuronal structure and function. The pathogenesis is intricate and involves a network of interactions among multiple causes and systems. Mitochondria and Ca2+ signaling have long been considered to play important roles in the development of various NDs. Mitochondrial fission and fusion dynamics are important processes of mitochondrial quality control, ensuring the stability of mitochondrial structure and function. Mitochondrial fission and fusion imbalance and Ca2+ signaling disorders can aggravate the disease progression of NDs. In this review, we explore the relationship between mitochondrial dynamics and Ca2+ signaling in AD, PD, ALS, and HD, focusing on the roles of key regulatory proteins (Drp1, Fis1, Mfn1/2, and Opa1) and the association structures between mitochondria and the endoplasmic reticulum (MERCs/MAMs). We provide a detailed analysis of their involvement in the pathogenesis of these four NDs. By integrating these mechanisms, we aim to clarify their contributions to disease progression and offer insights into the development of therapeutic strategies that target mitochondrial dynamics and Ca2+ signaling. We also examine the progress in drug research targeting these pathways, highlighting their potential as therapeutic targets in the treatment of NDs.

The unusual suspect: A novel role for intermediate filament proteins in mitochondrial morphology

Mitochondrial dynamics is crucial for cellular homeostasis. However, not all proteins involved are known. Using a protein-protein interaction (PPI) approach, we identified ITPRIPL2 for involvement in mitochondrial dynamics. ITPRIPL2 co-localizes with intermediate filament protein vimentin, supported by protein simulations. ITPRIPL2 knockdown reveals mitochondrial elongation, disrupts vimentin processing, intermediate filament formation, and alters vimentin-related pathways. Interestingly, vimentin knockdown also leads to mitochondrial elongation. These findings highlight ITPRIPL2 as vimentin-associated protein essential for intermediate filament structure and suggest a role for intermediate filaments in mitochondrial morphology. Our study demonstrates that PPI analysis is a powerful approach for identifying novel mitochondrial dynamics proteins.

Transmembrane Parkinson's disease mutation of PINK1 leads to altered mitochondrial anchoring

Parkinson's disease is a devastating neurodegenerative disease resulting from the death of dopaminergic neurons in the substantia nigra pars compacta of the midbrain. Familial and sporadic forms of the disease have been linked to mitochondrial dysfunction. Pathology has been identified with mutations in the PARK6 gene encoding PTEN-induced kinase 1 (PINK1), a quality control protein in the mitochondria. Disease-associated mutations at the transmembrane (TM) region of PINK1 protein were predicted to disrupt the cleavage of the TM region by the PARL (presenilin-associated rhomboid-like) protease at the inner mitochondrial membrane. Here, using microscopy, kinetic analysis, and molecular dynamics simulations, we analyzed three Parkinson's disease-associated TM mutations; PINK1-C92F, PINK1-R98W, and PINK1-I111S, and found that mitochondrial localization and cleavage by the PARL protease were not significantly impaired. However, clearance of hydrolyzed PINK1-R98W appears to be compromised because of altered positioning of the protein in the outer mitochondrial membrane, preventing association with translocase of the outer membrane complexes and slowing cleavage by PARL. This single amino acid change slows degradation of proteolyzed PINK1, increasing its accumulation at the outer mitochondrial membrane and resulting in increased mitophagy and decreased mitochondrial content among these cells.