Defective mitochondrial protein import contributes to complex I-induced mitochondrial dysfunction and neurodegeneration in Parkinson’s disease

The Role and Mechanism of Ambra1-Mediated Mitophagy in TDCPP-Exposed Mouse Hippocampal Neurons

Tri(1,3-dichloro-2-propyl)phosphate (TDCPP) is one of the most widely used organophosphorus flame retardants in consumer products. TDCPP has been confirmed to be neurotoxic, but its mechanism has not been clarified and may be related to mitophagy. AMBRA1 can promote neurological autophagy, but whether AMBRA1 is involved in the mechanism of TDCPP-induced neurotoxicity has not been elucidated. In this study, the optimal neuronal damage model was established by exposing mice hippocampal neurons to TDCPP. Furthermore, on the basis of this model, siRNA was used to knock down AMBRA1. Combined with qRT-PCR and Western blot techniques, we identified AMBRA1-mediated mitophagy-induced neuronal damage in vitro mechanism. The experimental results indicated that TDCPP treatment for 24 h led to a decrease in the cell viability of mouse hippocampal neurons, causing neuronal damage. Meanwhile, TDCPP exposure increased autophagy marker proteins p62 and LC3B, and down-regulated mitochondrial DNA ND1 damage and TOMM20 protein, suggesting that TDCPP exposure promoted mitophagy. In addition, TDCPP exposure led to changes in the expression of AMBRA1 and the key factors of mitophagy, FUNDC1, PINK1, and PARKIN, whereas mitophagy was inhibited after knockdown of AMBRA1. The research results indicated that exposure to TDCPP induced neuronal damage and promoted mitophagy. The mechanism may be that AMBRA1 promoted mitophagy in neuronal cells through the PARKIN-dependent/non-dependent pathway. This study revealed the toxic effects of TDCPP on the nervous system and its potential molecular mechanisms, which provided important clues for further understanding the mechanism of action of AMBAR1-mediated mitophagy.

Targeting NKAα1 to treat Parkinson's disease through inhibition of mitophagy-dependent ferroptosis

Dysfunction of the Na+/K+-ATPase (NKA) has been documented in various neurodegenerative diseases, yet the specific role of NKAα1 in Parkinson's disease (PD) remains incompletely understood. In this investigation, we utilized NKAα1 haploinsufficiency (NKAα1+/-) mice to probe the influence of NKAα1 on dopaminergic (DA) neurodegeneration induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our findings reveal that NKAα1+/- mice displayed a heightened loss of DA neurons and more pronounced motor dysfunction compared to the control group when exposed to MPTP. Intriguingly, this phenomenon coincided with the activation of ferroptosis and impaired mitophagy both in vivo and in vitro. To scrutinize the role and underlying mechanism of NKAα1 in PD, we employed DR-Ab, an antibody targeting the DR-region of the NKA α subunit. Our study demonstrates that the administration of DR-Ab effectively reinstated the membrane abundance of NKAα1, thereby mitigating MPTP-induced DA neuron loss and subsequent improvement in behavioral deficit. Mechanistically, DR-Ab heightened the formation of the surface NKAα1/SLC7A11 complex, inhibiting SLC7A11-dependent ferroptosis. Moreover, DR-Ab disrupted the cytosolic interaction between NKAα1 and Parkin, facilitating the translocation of Parkin to mitochondria and enhancing the process of mitophagy. In conclusion, this study establishes NKAα1 as a key regulator of ferroptosis and mitophagy, identifying its DR-region as a promising therapeutic target for PD.

Skeletal muscle atrophy after sciatic nerve damage: Mechanistic insights

Sciatic nerve injury leads to molecular events that cause muscular dysfunction advancement in atrophic conditions. Nerve damage renders muscles permanently relaxed which elevates intracellular resting Ca2+ levels. Increased Ca2+ levels are associated with several cellular signaling pathways including AMPK, cGMP, PLC-β, CERB, and calcineurin. Also, multiple enzymes involved in the tricarboxylic acid cycle and oxidative phosphorylation are activated by Ca2+ influx into mitochondria during muscle contraction, to meet increased ATP demand. Nerve damage induces mitophagy and skeletal muscle atrophy through increased sensitivity to Ca2+-induced opening of the permeability transition pore (PTP) in mitochondria attributed to Ca2+, ROS, and AMPK overload in muscle. Activated AMPK interacts negatively with Akt/mTOR is a highly prevalent and well-described central pathway for anabolic processes. Over the decade several reports indicate abnormal behavior of signaling machinery involved in denervation-induced muscle loss but end up with some controversial outcomes. Therefore, understanding how the synthesis and inhibitory stimuli interact with cellular signaling to control muscle mass and morphology may lead to new pharmacological insights toward understanding the underlying mechanism of muscle loss after sciatic nerve damage. Hence, the present review summarizes the existing literature on denervation-induced muscle atrophy to evaluate the regulation and expression of differential regulators during sciatic damage.

Evaluation of Mitochondrial Phagy (Mitophagy) in Human Non-small Adenocarcinoma Tumor Cells

Non-small cell lung cancer (NSCLC) is a predominant form of lung cancer characterized by its aggressive nature and high mortality rate, primarily due to late-stage diagnosis and metastatic spread. Recent studies underscore the pivotal role of mitophagy, a selective form of autophagy targeting damaged or superfluous mitochondria, in cancer biology, including NSCLC. Mitophagy regulation may influence cancer cell survival, proliferation, and metastasis by modulating mitochondrial quality and cellular energy homeostasis. Herein, we present a comprehensive methodology developed in our laboratory for the evaluation of mitophagy in NSCLC tumor cells. Utilizing a combination of immunoblotting, immunocytochemistry, and fluorescent microscopy, we detail the steps to quantify early and late mitophagy markers and mitochondrial dynamics. Our findings highlight the potential of targeting mitophagy pathways as a novel therapeutic strategy in NSCLC, offering insights into the complex interplay between mitochondrial dysfunction and tumor progression. This study not only sheds light on the significance of mitophagy in NSCLC but also establishes a foundational approach for its investigation, paving way for future research in this critical area of cancer biology.

Mitochondrial quality control pathways sense mitochondrial protein import

Mitochondrial quality control (MQC) mechanisms are required to maintain a functional proteome, which enables mitochondria to perform a myriad of important cellular functions from oxidative phosphorylation to numerous other metabolic pathways. Mitochondrial protein homeostasis begins with the import of over 1000 nuclear-encoded mitochondrial proteins and the synthesis of 13 mitochondrial DNA-encoded proteins. A network of chaperones and proteases helps to fold new proteins and degrade unnecessary, damaged, or misfolded proteins, whereas more extensive damage can be removed by mitochondrial-derived vesicles (MDVs) or mitochondrial autophagy (mitophagy). Here, focusing on mechanisms in mammalian cells, we review the importance of mitochondrial protein import as a sentinel of mitochondrial function that activates multiple MQC mechanisms when impaired.

The E3 ligase HUWE1 increases the sensitivity of CRC to oxaliplatin through TOMM20 degradation

Continuous administration of oxaliplatin, the most widely used first-line chemotherapy drug for colorectal cancer (CRC), eventually leads to drug resistance. Increasing the sensitivity of CRC cells to oxaliplatin is a key strategy to overcome this issue. Impairment of mitochondrial function is a pivotal mechanism determining the sensitivity of CRC to oxaliplatin. We discovered an inverse correlation between Translocase of Outer Mitochondrial Membrane 20 (TOMM20) and oxaliplatin sensitivity as well as an inverse relationship between TOMM20 and HECT, UBA, and WWE domain containing E3 ligase 1 (HUWE1) expression in CRC. For the first time, we demonstrated that HUWE1 ubiquitinates TOMM20 directly and also regulates TOMM20 degradation via the PARKIN-mediated pathway. Furthermore, we showed that overexpression of HUWE1 in CRC cells has a negative effect on mitochondrial function, including the generation of ATP and maintenance of mitochondrial membrane potential, leading to increased production of ROS and apoptosis. This effect was amplified when cells were treated simultaneously with oxaliplatin. Our study conclusively shows that TOMM20 is a novel target of HUWE1. Our findings indicate that HUWE1 plays a critical role in regulating oxaliplatin sensitivity by degrading TOMM20 and inducing mitochondrial damage in CRC.

Loss of mitochondrial adaptation associates with deterioration of mitochondrial turnover and structure in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Obesity and type 2 diabetes frequently have metabolic dysfunction-associated steatotic liver disease (MASLD) including steatohepatitis (MASH). In obesity, the liver may adapt its oxidative capacity, but the role of mitochondrial turnover in MASLD remains uncertain.

METHODS

This cross-sectional study compared individuals with class III obesity (n = 8/group) without (control, OBE CON; NAFLD activity score: 0.4 ± 0.1) or with steatosis (OBE MASL, 2.3 ± 0.4), or MASH (OBE MASH, 5.3 ± 0.3, p < 0.05 vs. other groups). Hepatic mitochondrial ultrastructure was assessed by transmission electron microscopy, mitochondrial respiration by high-resolution respirometry, biomarkers of mitochondrial quality control and endoplasmic reticulum (ER) stress by Western Blot.

RESULTS

Mitochondrial oxidative capacity was 31 % higher in OBE MASL, but 25 % lower in OBE MASH (p < 0.05 vs. OBE CON). OBE MASH showed ~1.5fold lower mitochondrial number, but ~1.2-1.5fold higher diameter and area (p < 0.001 vs. other groups). Biomarkers of autophagy (p62), mitophagy (PINK1, PARKIN), fission (DRP-1, FIS1) and fusion (MFN1/2, OPA1) were reduced in OBE MASH (p < 0.05 vs. OBE CON). OBE MASL showed lower p62, p-PARKIN/PARKIN, and p-DRP-1 (p < 0.05 vs. OBE CON). OBE MASL and MASH showed higher ER stress markers (PERK, ATF4, p-eIF2α-S51/eIF2α; p < 0.05 vs. OBE CON). Mitochondrial diameter associated inversely with fusion/fission biomarkers and with oxidative capacity, but positively with H2O2.

CONCLUSION

Humans with hepatic steatosis already exhibit impaired mitochondrial turnover, despite upregulated oxidative capacity, and evidence for ER stress. In MASH, oxidative stress likely mediates progressive decline of mitochondrial turnover, ultrastructure and respiration indicating that mitochondrial quality control is key for energy metabolism and may have potential for targeting MASH. ClinGovTrial:NCT01477957.

Mitochondrial damage and impaired mitophagy contribute to disease progression in SCA6

Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disease that manifests in midlife and progressively worsens with age. SCA6 is rare, and many patients are not diagnosed until long after disease onset. Whether disease-causing cellular alterations differ at different disease stages is currently unknown, but it is important to answer this question in order to identify appropriate therapeutic targets across disease duration. We used transcriptomics to identify changes in gene expression at disease onset in a well-established mouse model of SCA6 that recapitulates key disease features. We observed both up- and down-regulated genes with the major down-regulated gene ontology terms suggesting mitochondrial dysfunction. We explored mitochondrial function and structure and observed that changes in mitochondrial structure preceded changes in function, and that mitochondrial function was not significantly altered at disease onset but was impaired later during disease progression. We also detected elevated oxidative stress in cells at the same disease stage. In addition, we observed impairment in mitophagy that exacerbates mitochondrial dysfunction at late disease stages. In post-mortem SCA6 patient cerebellar tissue, we observed metabolic changes that are consistent with mitochondrial impairments, supporting our results from animal models being translatable to human disease. Our study reveals that mitochondrial dysfunction and impaired mitochondrial degradation likely contribute to disease progression in SCA6 and suggests that these could be promising targets for therapeutic interventions in particular for patients diagnosed after disease onset.

Cell-free chromatin particles released from dying cells inflict mitochondrial damage and ROS production in living cells

Mitochondrial damage and the resultant oxidative stress are associated with neurodegenerative diseases, ageing, and cancer. However, the triggers of mitochondrial damage remain unclear. We previously reported that cell-free chromatin particles (cfChPs) released from the billions of cells that die in the body every day can readily enter healthy cells and damage their DNA. Here, we show that cfChPs isolated from the sera of healthy individuals, when applied to NIH3T3 mouse fibroblast cells, cause physical damage to mitochondrial DNA (mtDNA). cfChPs also induce ultrastructural changes, increase mitochondrial mass, alter mitochondrial shape, upregulate mitochondrial outer membrane protein translocase of the outer membrane 20, and change mitochondrial membrane potential. Furthermore, a marked increase was observed in mitochondrial superoxide (ROS) production, as detected by MitoSOX Red, and intracellular superoxide dismutase-1 activation. ROS production was also activated when a conditioned medium containing cfChPs released from hypoxia-induced dying NIH3T3 cells was applied to healthy NIH3T3 cells. ROS activation was significantly reduced when the conditioned medium was pre-treated with three different cfChP-deactivating agents: anti-histone antibody-complexed nanoparticles, DNase I, and the novel pro-oxidant combination of the nutraceuticals resveratrol and copper. Given that 1 × 109-1 × 1012 cells die in the body every day, we hypothesise that cfChPs from dying cells are the major physiological triggers for mtDNA damage and ROS production. Deactivation of cfChPs may provide a novel therapeutic approach to retard ageing and associated degenerative conditions linked to oxidative stress.

Ferroptosis of Microglia in Aging Human White Matter Injury

OBJECTIVE

Because the role of white matter (WM) degenerating microglia (DM) in remyelination failure is unclear, we sought to define the core features of this novel population of aging human microglia.

METHODS

We analyzed postmortem human brain tissue to define a population of DM in aging WM lesions. We used immunofluorescence staining and gene expression analysis to investigate molecular mechanisms related to the degeneration of DM.

RESULTS

We found that DM, which accumulated myelin debris were selectively enriched in the iron-binding protein light chain ferritin, and accumulated PLIN2-labeled lipid droplets. DM displayed lipid peroxidation injury and enhanced expression for TOM20, a mitochondrial translocase, and a sensor of oxidative stress. DM also displayed enhanced expression of the DNA fragmentation marker phospho-histone H2A.X. We identified a unique set of ferroptosis-related genes involving iron-mediated lipid dysmetabolism and oxidative stress that were preferentially expressed in WM injury relative to gray matter neurodegeneration.

INTERPRETATION

Ferroptosis appears to be a major mechanism of WM injury in Alzheimer's disease and vascular dementia. WM DM are a novel therapeutic target to potentially reduce the impact of WM injury and myelin loss on the progression of cognitive impairment. ANN NEUROL 2023;94:1048-1066.

The interaction between alpha-synuclein and mitochondrial dysfunction in Parkinson's disease

Parkinson's disease (PD) is an aging-associated neurodegenerative disorder with the hallmark of abnormal aggregates of alpha-synuclein (α-syn) in Lewy bodies (LBs) and Lewy neurites (LNs). Currently, pathogenic α-syn and mitochondrial dysfunction have been considered as prominent roles that give impetus to the PD onset. This review describes the α-syn pathology and mitochondrial alterations in PD, and focuses on how α-syn interacts with multiple aspects of mitochondrial homeostasis in the pathogenesis of PD.

WGX50 mitigates doxorubicin-induced cardiotoxicity through inhibition of mitochondrial ROS and ferroptosis

BACKGROUND

Doxorubicin (DOX)-induced cardiotoxicity (DIC) is a major impediment to its clinical application. It is indispensable to explore alternative treatment molecules or drugs for mitigating DIC. WGX50, an organic extract derived from Zanthoxylum bungeanum Maxim, has anti-inflammatory and antioxidant biological activity, however, its function and mechanism in DIC remain unclear.

METHODS

We established DOX-induced cardiotoxicity models both in vitro and in vivo. Echocardiography and histological analyses were used to determine the severity of cardiac injury in mice. The myocardial damage markers cTnT, CK-MB, ANP, BNP, and ferroptosis associated indicators Fe2+, MDA, and GPX4 were measured using ELISA, RT-qPCR, and western blot assays. The morphology of mitochondria was investigated with a transmission electron microscope. The levels of mitochondrial membrane potential, mitochondrial ROS, and lipid ROS were detected using JC-1, MitoSOX™, and C11-BODIPY 581/591 probes.

RESULTS

Our findings demonstrate that WGX50 protects DOX-induced cardiotoxicity via restraining mitochondrial ROS and ferroptosis. In vivo, WGX50 effectively relieves doxorubicin-induced cardiac dysfunction, cardiac injury, fibrosis, mitochondrial damage, and redox imbalance. In vitro, WGX50 preserves mitochondrial function by reducing the level of mitochondrial membrane potential and increasing mitochondrial ATP production. Furthermore, WGX50 reduces iron accumulation and mitochondrial ROS, increases GPX4 expression, and regulates lipid metabolism to inhibit DOX-induced ferroptosis.

CONCLUSION

Taken together, WGX50 protects DOX-induced cardiotoxicity via mitochondrial ROS and the ferroptosis pathway, which provides novel insights for WGX50 as a promising drug candidate for cardioprotection.

Construction of an Exudative Age-Related Macular Degeneration Diagnostic and Therapeutic Molecular Network Using Multi-Layer Network Analysis, a Fuzzy Logic Model, and Deep Learning Techniques: Are Retinal and Brain Neurodegenerative Disorders Related?

Neovascular age-related macular degeneration (nAMD) is a leading cause of irreversible visual impairment in the elderly. The current management of nAMD is limited and involves regular intravitreal administration of anti-vascular endothelial growth factor (anti-VEGF). However, the effectiveness of these treatments is limited by overlapping and compensatory pathways leading to unresponsiveness to anti-VEGF treatments in a significant portion of nAMD patients. Therefore, a system view of pathways involved in pathophysiology of nAMD will have significant clinical value. The aim of this study was to identify proteins, miRNAs, long non-coding RNAs (lncRNAs), various metabolites, and single-nucleotide polymorphisms (SNPs) with a significant role in the pathogenesis of nAMD. To accomplish this goal, we conducted a multi-layer network analysis, which identified 30 key genes, six miRNAs, and four lncRNAs. We also found three key metabolites that are common with AMD, Alzheimer's disease (AD) and schizophrenia. Moreover, we identified nine key SNPs and their related genes that are common among AMD, AD, schizophrenia, multiple sclerosis (MS), and Parkinson's disease (PD). Thus, our findings suggest that there exists a connection between nAMD and the aforementioned neurodegenerative disorders. In addition, our study also demonstrates the effectiveness of using artificial intelligence, specifically the LSTM network, a fuzzy logic model, and genetic algorithms, to identify important metabolites in complex metabolic pathways to open new avenues for the design and/or repurposing of drugs for nAMD treatment.

α-Synuclein oligomers and fibrils: partners in crime in synucleinopathies

The misfolding and aggregation of α-synuclein is the general hallmark of a group of devastating neurodegenerative pathologies referred to as synucleinopathies, such as Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. In such conditions, a range of different misfolded aggregates, including oligomers, protofibrils, and fibrils, are present both in neurons and glial cells. Growing experimental evidence supports the proposition that soluble oligomeric assemblies, formed during the early phases of the aggregation process, are the major culprits of neuronal toxicity; at the same time, fibrillar conformers appear to be the most efficient at propagating among interconnected neurons, thus contributing to the spreading of α-synuclein pathology. Moreover, α-synuclein fibrils have been recently reported to release soluble and highly toxic oligomeric species, responsible for an immediate dysfunction in the recipient neurons. In this review, we discuss the current knowledge about the plethora of mechanisms of cellular dysfunction caused by α-synuclein oligomers and fibrils, both contributing to neurodegeneration in synucleinopathies.

Research progress in the molecular mechanism of ferroptosis in Parkinson's disease and regulation by natural plant products

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder of the central nervous system after Alzheimer's disease. The current understanding of PD focuses mainly on the loss of dopamine neurons in the substantia nigra region of the midbrain, which is attributed to factors such as oxidative stress, alpha-synuclein aggregation, neuroinflammation, and mitochondrial dysfunction. These factors together contribute to the PD phenotype. Recent studies on PD pathology have introduced a new form of cell death known as ferroptosis. Pathological changes closely linked with ferroptosis have been seen in the brain tissues of PD patients, including alterations in iron metabolism, lipid peroxidation, and increased levels of reactive oxygen species. Preclinical research has demonstrated the neuroprotective qualities of certain iron chelators, antioxidants, Fer-1, and conditioners in Parkinson's disease. Natural plant products have shown significant potential in balancing ferroptosis-related factors and adjusting their expression levels. Therefore, it is vital to understand the mechanisms by which natural plant products inhibit ferroptosis and relieve PD symptoms. This review provides a comprehensive look at ferroptosis, its role in PD pathology, and the mechanisms underlying the therapeutic effects of natural plant products focused on ferroptosis. The insights from this review can serve as useful references for future research on novel ferroptosis inhibitors and lead compounds for PD treatment.

AR antagonists develop drug resistance through TOMM20 autophagic degradation-promoted transformation to neuroendocrine prostate cancer

BACKGROUND

Prostate cancer(PCa) is the most commonly occurring male cancer in the USA. Abiraterone or Enzalutamide have been approved for the treatment of metastatic castration-resistant prostate cancer (CRPC). However, the treatment-emergent neuroendocrine PCa (t-NEPC) may develop, resulting in drug resistance in about 10-17% CRPC patients. The detailed mechanisms remain unclear..

METHODS

The expression correlation of TOMM20 and AR in PCa was determined by analyzing publicly available datasets, or by IHC staining in tumor specimens. The protein interaction of TOMM20 and AR was validated by co-immunoprecipitation or GST pull-down assay. The impact of TOMM20 depletion on drug sensitivity were elucidated by assays of cell proliferation, invasion, sphere formation, xenograft growth and intravenous metastasis. The intracellular ROS level was measured by flow cytometry, and the NEPC transdifferentiation and characteristics of cancer stem-like cells were validated by RNA-seq, RT-PCR and western blotting.

RESULTS

The protein level of TOMM20 is positively correlated with AR in PCa cells and specimens. TOMM20 protein physically interacts with AR. AR antagonists induced the protein degradation of TOMM20 through autophagy-lysosomal pathway, thereby elevating the intracellular ROS level and activating PI3K/AKT signaling pathway. When TOMM20 was depleted, PCa cells underwent EMT, acquired the characteristics of cancer stem-like cells, and developed resistance to AR antagonists. The stable depletion of TOMM20 promoted the transdifferentiation of PCa adenocarcinoma into NEPC and metastasis. Conversely, the rescue of TOMM20 re-sensitized the resistant PCa cells to AR antagonists.

CONCLUSIONS

TOMM20 protein degradation induced by AR antagonists promoted the transdifferentiation of PCa to NEPC, thereby revealing a novel molecular mechanism by which AR antagonists develop drug resistance through mitochondrial outer membrane-mediated signaling pathway. These findings suggested that the decreasing or loss of TOMM20 expression in PCa tissues might become a useful predictor of PCa resistance to AR antagonists.

Immunoproteasome-specific subunit PSMB9 induction is required to regulate cellular proteostasis upon mitochondrial dysfunction

Perturbed cellular protein homeostasis (proteostasis) and mitochondrial dysfunction play an important role in neurodegenerative diseases, however, the interplay between these two phenomena remains unclear. Mitochondrial dysfunction leads to a delay in mitochondrial protein import, causing accumulation of non-imported mitochondrial proteins in the cytosol and challenging proteostasis. Cells respond by increasing proteasome activity and molecular chaperones in yeast and C. elegans. Here, we demonstrate that in human cells mitochondrial dysfunction leads to the upregulation of a chaperone HSPB1 and, interestingly, an immunoproteasome-specific subunit PSMB9. Moreover, PSMB9 expression is dependent on the translation elongation factor EEF1A2. These mechanisms constitute a defense response to preserve cellular proteostasis under mitochondrial stress. Our findings define a mode of proteasomal activation through the change in proteasome composition driven by EEF1A2 and its spatial regulation, and are useful to formulate therapies to prevent neurodegenerative diseases.

Maternal obesity alters the placental transcriptome in a fetal sex-dependent manner

Infants born to obese mothers have an increased risk of developing obesity and metabolic diseases in childhood and adulthood. Although the molecular mechanisms linking maternal obesity during pregnancy to the development of metabolic diseases in offspring are poorly understood, evidence suggests that changes in the placental function may play a role. Using a mouse model of diet-induced obesity with fetal overgrowth, we performed RNA-seq analysis at embryonic day 18.5 to identify genes differentially expressed in the placentas of obese and normal-weight dams (controls). In male placentas, 511 genes were upregulated and 791 genes were downregulated in response to maternal obesity. In female placentas, 722 genes were downregulated and 474 genes were upregulated in response to maternal obesity. The top canonical pathway downregulated in maternal obesity in male placentas was oxidative phosphorylation. In contrast, sirtuin signaling, NF-kB signaling, phosphatidylinositol, and fatty acid degradation were upregulated. In female placentas, the top canonical pathways downregulated in maternal obesity were triacylglycerol biosynthesis, glycerophospholipid metabolism, and endocytosis. In contrast, bone morphogenetic protein, TNF, and MAPK signaling were upregulated in the female placentas of the obese group. In agreement with RNA-seq data, the expression of proteins associated with oxidative phosphorylation was downregulated in male but not female placentas of obese mice. Similarly, sex-specific changes in the protein expression of mitochondrial complexes were found in placentas collected from obese women delivering large-for-gestational-age (LGA) babies. In conclusion, maternal obesity with fetal overgrowth differentially regulates the placental transcriptome in male and female placentas, including genes involved in oxidative phosphorylation.

Mitochondrial dysfunction rapidly modulates the abundance and thermal stability of cellular proteins

Cellular functionality relies on a well-balanced, but highly dynamic proteome. Dysfunction of mitochondrial protein import leads to the cytosolic accumulation of mitochondrial precursor proteins which compromise cellular proteostasis and trigger a mitoprotein-induced stress response. To dissect the effects of mitochondrial dysfunction on the cellular proteome as a whole, we developed pre-post thermal proteome profiling. This multiplexed time-resolved proteome-wide thermal stability profiling approach with isobaric peptide tags in combination with a pulsed SILAC labelling elucidated dynamic proteostasis changes in several dimensions: In addition to adaptations in protein abundance, we observed rapid modulations of the thermal stability of individual cellular proteins. Different functional groups of proteins showed characteristic response patterns and reacted with group-specific kinetics, allowing the identification of functional modules that are relevant for mitoprotein-induced stress. Thus, our new pre-post thermal proteome profiling approach uncovered a complex response network that orchestrates proteome homeostasis in eukaryotic cells by time-controlled adaptations of the abundance and the conformation of proteins.

CBL0137 activates ROS/BAX signaling to promote caspase-3/GSDME-dependent pyroptosis in ovarian cancer cells

Curaxin CBL0137 was designed to regulate p53 and nuclear factor-κB simultaneously and exhibits antitumor activity by inhibiting tumor cell proliferation and inducing apoptosis in multiple cancers. However, whether CBL0137 can induce pyroptosis has not yet been reported. This study demonstrated that CBL0137 induces caspase-3/gasdermin E (GSDME)-dependent pyroptosis via the reactive oxygen species (ROS)/BAX pathway. In ovarian cancer cells, CBL0137 inactivated the chromatin remodeling complex which could facilitate chromatin transcription, leading to the decreased transcription of antioxidant genes and oxidation and causing increased ROS levels. BAX was recruited on the mitochondrial membrane by mitochondrial ROS and induced the release of cytochrome c to cleave caspase-3. This led to the cleavage of the N-terminal of GSDME to form pores on the cell membrane and induced pyroptosis. Results of in vivo experiments revealed that CBL0137 also had anti-tumor effects on ovarian cancer cells in vivo. Our study outcomes reveal the mechanisms and targets of CBL0137 inducing pyroptosis in ovarian cancer cells and indicate that CBL0137 is a promising therapeutic agent for ovarian cancer.

The Role of Exercise in Maintaining Mitochondrial Proteostasis in Parkinson's Disease

Parkinson's disease (PD) is the second most common rapidly progressive neurodegenerative disease and has serious health and socio-economic consequences. Mitochondrial dysfunction is closely related to the onset and progression of PD, and the use of mitochondria as a target for PD therapy has been gaining traction in terms of both recognition and application. The disruption of mitochondrial proteostasis in the brain tissue of PD patients leads to mitochondrial dysfunction, which manifests as mitochondrial unfolded protein response, mitophagy, and mitochondrial oxidative phosphorylation. Physical exercise is important for the maintenance of human health, and has the great advantage of being a non-pharmacological therapy that is non-toxic, low-cost, and universally applicable. In this review, we investigate the relationships between exercise, mitochondrial proteostasis, and PD and explore the role and mechanisms of mitochondrial proteostasis in delaying PD through exercise.

Spike Protein Impairs Mitochondrial Function in Human Cardiomyocytes: Mechanisms Underlying Cardiac Injury in COVID-19

Background: COVID-19 has a major impact on cardiovascular diseases and may lead to myocarditis or cardiac failure. The clove-like spike (S) protein of SARS-CoV-2 facilitates its transmission and pathogenesis. Cardiac mitochondria produce energy for key heart functions. We hypothesized that S1 would directly impair the functions of cardiomyocyte mitochondria, thus causing cardiac dysfunction. Methods: Through the Seahorse Mito Stress Test and real-time ATP rate assays, we explored the mitochondrial bioenergetics in human cardiomyocytes (AC16). The cells were treated without (control) or with S1 (1 nM) for 24, 48, and 72 h and we observed the mitochondrial morphology using transmission electron microscopy and confocal fluorescence microscopy. Western blotting, XRhod-1, and MitoSOX Red staining were performed to evaluate the expression of proteins related to energetic metabolism and relevant signaling cascades, mitochondrial Ca2+ levels, and ROS production. Results: The 24 h S1 treatment increased ATP production and mitochondrial respiration by increasing the expression of fatty-acid-transporting regulators and inducing more negative mitochondrial membrane potential (Δψm). The 72 h S1 treatment decreased mitochondrial respiration rates and Δψm, but increased levels of reactive oxygen species (ROS), mCa2+, and intracellular Ca2+. Electron microscopy revealed increased mitochondrial fragmentation/fission in AC16 cells treated for 72 h. The effects of S1 on ATP production were completely blocked by neutralizing ACE2 but not CD147 antibodies, and were partly attenuated by Mitotempo (1 µM). Conclusion: S1 might impair mitochondrial function in human cardiomyocytes by altering Δψm, mCa2+ overload, ROS accumulation, and mitochondrial dynamics via ACE2.

Transferred mitochondria accumulate reactive oxygen species, promoting proliferation

Recent studies reveal that lateral mitochondrial transfer, the movement of mitochondria from one cell to another, can affect cellular and tissue homeostasis. Most of what we know about mitochondrial transfer stems from bulk cell studies and have led to the paradigm that functional transferred mitochondria restore bioenergetics and revitalize cellular functions to recipient cells with damaged or non-functional mitochondrial networks. However, we show that mitochondrial transfer also occurs between cells with functioning endogenous mitochondrial networks, but the mechanisms underlying how transferred mitochondria can promote such sustained behavioral reprogramming remain unclear. We report that unexpectedly, transferred macrophage mitochondria are dysfunctional and accumulate reactive oxygen species in recipient cancer cells. We further discovered that reactive oxygen species accumulation activates ERK signaling, promoting cancer cell proliferation. Pro-tumorigenic macrophages exhibit fragmented mitochondrial networks, leading to higher rates of mitochondrial transfer to cancer cells. Finally, we observe that macrophage mitochondrial transfer promotes tumor cell proliferation in vivo. Collectively these results indicate that transferred macrophage mitochondria activate downstream signaling pathways in a ROS-dependent manner in cancer cells, and provide a model of how sustained behavioral reprogramming can be mediated by a relatively small amount of transferred mitochondria in vitro and in vivo.

Impact of blood factors on endothelial cell metabolism and function in two diverse heart failure models

Role of blood-based factors in development and progression of heart failure (HF) is poorly characterized. Blood contains factors released during pathophysiological states that may impact cellular function and provide mechanistic insights to HF management. We tested effects of blood from two distinct HF models on cardiac metabolism and identified possible cellular targets of the effects. Blood plasma was obtained from daunorubicin- and myocardial infarction-induced HF rabbits (Dauno-HF and MI-HF) and their controls (Dauno-Control and MI-Control). Effects of plasma on bioenergetics of myocardial tissue from healthy mice and cellular cardiac components were assessed using high-resolution respirometry and Seahorse flux analyzer. Since endothelial cell respiration was profoundly affected by HF plasma, effects of plasma on endothelial cell barrier function and death were further evaluated. Western-blotting and electron microscopy were performed to evaluate mitochondrial proteins and morphology. Brief exposure to HF plasma decreased cardiac tissue respiration. Endothelial cell respiration was most impacted by exposure to HF plasma. Endothelial cell monolayer integrity was decreased by incubation with Dauno-HF plasma. Apoptosis and necrosis were increased in cells incubated with Dauno-HF plasma for 24 h. Down-regulation of voltage-dependent anion-selective channel (VDAC)-1, translocase of outer membrane 20 (Tom20), and mitochondrial fission factor (MFF) in cells exposed to Dauno-HF plasma and mitochondrial signal transducer and activator of transcription 3 (Stat3) and MFF in cells exposed to MI-HF plasma were observed. Mitochondrial structure was disrupted in cells exposed to HF plasma. These findings indicate that endothelial cells and mitochondrial structure and function may be primary target where HF pathology manifests and accelerates. High-throughput blood-based screening of HF may provide innovative ways to advance disease diagnosis and management.

8-paradol from ginger exacerbates PINK1/Parkin mediated mitophagy to induce apoptosis in human gastric adenocarcinoma

Gastric cancer (GC) occurs in the gastric mucosa, and its high morbidity and mortality make it an international health crisis. Therefore, novel drugs are needed for its treatment. The use of natural products and their components in cancer treatments has shown promise. Therefore, this study aimed to evaluate the effect of 8-paradol, a phenolic compound isolated from ginger (Zingiber officinale Roscoe), on GC and determine its underlying mechanisms of action. In this study, repeated column chromatography was conducted on ginger EtOH extract to isolate gingerol and its derivatives. The cytotoxicity of the eight ginger compounds underwent a (3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide) tetrazolium reduction (MTT) assay. 8-paradol showed the most potent cytotoxicity effect among the isolated ginger compounds. The underlying mechanism by which 8-paradol regulated specific proteins in AGS cells was evaluated by proteomic analysis. To validate the predicted mechanisms, AGS cells and thymus-deficient nude mice bearing AGS xenografts were used as in vitro and in vivo models of GC, respectively. The results showed that the 8-paradol promoted PINK1/Parkin-associated mitophagy, mediating cell apoptosis. Additionally, the inhibition of mitophagy by chloroquine (CQ) ameliorated 8-paradol-induced mitochondrial dysfunction and apoptosis, supporting a causative role for mitophagy in the 8-paradol-induced anticancer effect. Molecular docking results revealed the molecular interactions between 8-paradol and mitophagy-/ apoptosis-related proteins at the atomic level. Our study provides strong evidence that 8-paradol could act as a novel potential therapeutic agent to suppress the progression of GC by targeting mitophagy pathway.

An increase in mitochondrial TOM activates apoptosis to drive retinal neurodegeneration

Intronic polymorphic TOMM40 variants increasing TOMM40 mRNA expression are strongly correlated to late onset Alzheimer's Disease. The gene product, hTomm40, encoded in the APOE gene cluster, is a core component of TOM, the translocase that imports nascent proteins across the mitochondrial outer membrane. We used Drosophila melanogaster eyes as an in vivo model to investigate the relationship between elevated Tom40 (the Drosophila homologue of hTomm40) expression and neurodegeneration. Here we provide evidence that an overabundance of Tom40 in mitochondria invokes caspase-dependent cell death in a dose-dependent manner, leading to degeneration of the primarily neuronal eye tissue. Degeneration is contingent on the availability of co-assembling TOM components, indicating that an increase in assembled TOM is the factor that triggers apoptosis and degeneration in a neural setting. Eye death is not contingent on inner membrane translocase components, suggesting it is unlikely to be a direct consequence of impaired import. Another effect of heightened Tom40 expression is upregulation and co-association of a mitochondrial oxidative stress biomarker, DmHsp22, implicated in extension of lifespan, providing new insight into the balance between cell survival and death. Activation of regulated death pathways, culminating in eye degeneration, suggests a possible causal route from TOMM40 polymorphisms to neurodegenerative disease.

Mitochondrial Dysfunction: Pathophysiology and Mitochondria-Targeted Drug Delivery Approaches

Mitochondria are implicated in a wide range of functions apart from ATP generation, and, therefore, constitute one of the most important organelles of cell. Since healthy mitochondria are essential for proper cellular functioning and survival, mitochondrial dysfunction may lead to various pathologies. Mitochondria are considered a novel and promising therapeutic target for the diagnosis, treatment, and prevention of various human diseases including metabolic disorders, cancer, and neurodegenerative diseases. For mitochondria-targeted therapy, there is a need to develop an effective drug delivery approach, owing to the mitochondrial special bilayer structure through which therapeutic molecules undergo multiple difficulties in reaching the core. In recent years, various nanoformulations have been designed such as polymeric nanoparticles, liposomes, inorganic nanoparticles conjugate with mitochondriotropic moieties such as mitochondria-penetrating peptides (MPPs), triphenylphosphonium (TPP), dequalinium (DQA), and mitochondrial protein import machinery for overcoming barriers involved in targeting mitochondria. The current approaches used for mitochondria-targeted drug delivery have provided promising ways to overcome the challenges associated with targeted-drug delivery. Herein, we review the research from past years to the current scenario that has identified mitochondrial dysfunction as a major contributor to the pathophysiology of various diseases. Furthermore, we discuss the recent advancements in mitochondria-targeted drug delivery strategies for the pathologies associated with mitochondrial dysfunction.

Iron Brain Menace: The Involvement of Ferroptosis in Parkinson Disease

Parkinson disease (PD) is the second-most common neurodegenerative disease. The characteristic pathology of progressive dopaminergic neuronal loss in people with PD is associated with iron accumulation and is suggested to be driven in part by the novel cell death pathway, ferroptosis. A unique modality of cell death, ferroptosis is mediated by iron-dependent phospholipid peroxidation. The mechanisms of ferroptosis inhibitors enhance antioxidative capacity to counter the oxidative stress from lipid peroxidation, such as through the system x_c^-/glutathione (GSH)/glutathione peroxidase 4 (GPX4) axis and the coenzyme Q10 (CoQ10)/FSP1 pathway. Another means to reduce ferroptosis is with iron chelators. To date, there is no disease-modifying therapy to cure or slow PD progression, and a recent topic of research seeks to intervene with the development of PD via regulation of ferroptosis. In this review, we provide a discussion of different cell death pathways, the molecular mechanisms of ferroptosis, the role of ferroptosis in blood-brain barrier damage, updates on PD studies in ferroptosis, and the latest progress of pharmacological agents targeting ferroptosis for the intervention of PD in clinical trials.

Molecular and Cellular Interactions in Pathogenesis of Sporadic Parkinson Disease

An increasing number of the population all around the world suffer from age-associated neurodegenerative diseases including Parkinson’s disease (PD). This disorder presents different signs of genetic, epigenetic and environmental origin, and molecular, cellular and intracellular dysfunction. At the molecular level, α-synuclein (αSyn) was identified as the principal molecule constituting the Lewy bodies (LB). The gut microbiota participates in the pathogenesis of PD and may contribute to the loss of dopaminergic neurons through mitochondrial dysfunction. The most important pathogenetic link is an imbalance of Ca²⁺ ions, which is associated with redox imbalance in the cells and increased generation of reactive oxygen species (ROS). In this review, genetic, epigenetic and environmental factors that cause these disorders and their cause-and-effect relationships are considered. As a constituent of environmental factors, the example of organophosphates (OPs) is also reviewed. The role of endothelial damage in the pathogenesis of PD is discussed, and a ‘triple hit hypothesis’ is proposed as a modification of Braak’s dual hit one. In the absence of effective therapies for neurodegenerative diseases, more and more evidence is emerging about the positive impact of nutritional structure and healthy lifestyle on the state of blood vessels and the risk of developing these diseases.

Peripheral Auditory Nerve Impairment in a Mouse Model of Syndromic Autism

Dysfunction of the peripheral auditory nerve (AN) contributes to dynamic changes throughout the central auditory system, resulting in abnormal auditory processing, including hypersensitivity. Altered sound sensitivity is frequently observed in autism spectrum disorder (ASD), suggesting that AN deficits and changes in auditory information processing may contribute to ASD-associated symptoms, including social communication deficits and hyperacusis. The MEF2C transcription factor is associated with risk for several neurodevelopmental disorders, and mutations or deletions of MEF2C produce a haploinsufficiency syndrome characterized by ASD, language, and cognitive deficits. A mouse model of this syndromic ASD (Mef2c-Het) recapitulates many of the MEF2C haploinsufficiency syndrome-linked behaviors, including communication deficits. We show here that Mef2c-Het mice of both sexes exhibit functional impairment of the peripheral AN and a modest reduction in hearing sensitivity. We find that MEF2C is expressed during development in multiple AN and cochlear cell types; and in Mef2c-Het mice, we observe multiple cellular and molecular alterations associated with the AN, including abnormal myelination, neuronal degeneration, neuronal mitochondria dysfunction, and increased macrophage activation and cochlear inflammation. These results reveal the importance of MEF2C function in inner ear development and function and the engagement of immune cells and other non-neuronal cells, which suggests that microglia/macrophages and other non-neuronal cells might contribute, directly or indirectly, to AN dysfunction and ASD-related phenotypes. Finally, our study establishes a comprehensive approach for characterizing AN function at the physiological, cellular, and molecular levels in mice, which can be applied to animal models with a wide range of human auditory processing impairments.SIGNIFICANCE STATEMENT This is the first report of peripheral auditory nerve (AN) impairment in a mouse model of human MEF2C haploinsufficiency syndrome that has well-characterized ASD-related behaviors, including communication deficits, hyperactivity, repetitive behavior, and social deficits. We identify multiple underlying cellular, subcellular, and molecular abnormalities that may contribute to peripheral AN impairment. Our findings also highlight the important roles of immune cells (e.g., cochlear macrophages) and other non-neuronal elements (e.g., glial cells and cells in the stria vascularis) in auditory impairment in ASD. The methodological significance of the study is the establishment of a comprehensive approach for evaluating peripheral AN function and impact of peripheral AN deficits with minimal hearing loss.

Mitophagy and reactive oxygen species interplay in Parkinson's disease

Mitophagy impairment and oxidative stress are cardinal pathological hallmarks in Parkinson's disease (PD), a common age-related neurodegenerative condition. The specific interactions between mitophagy and reactive oxygen species (ROS) have attracted considerable attention even though their exact interplay in PD has not been fully elucidated. We highlight the interactions between ROS and mitophagy, with a focus on the signalling pathways downstream to ROS that triggers mitophagy and draw attention to potential therapeutic compounds that target these pathways in both experimental and clinical models. Identifying a combination of ROS inhibitors and mitophagy activators to provide a physiologic balance in this complex signalling pathways may lead to a more optimal outcome. Deciphering the exact temporal relationship between mitophagy and oxidative stress and their triggers early in the course of neurodegeneration can unravel mechanistic clues that potentially lead to the development of compounds for clinical drug trials focusing on prodromic PD or at-risk individuals.

Oxidative Stress and Mitochondrial Complex I Dysfunction Correlate with Neurodegeneration in an α-Synucleinopathy Animal Model

The α-synucleinopathies constitute a subset of neurodegenerative disorders, of which Parkinson’s disease (PD) is the most common worldwide, characterized by the accumulation of misfolded α-synuclein in the cytoplasm of neurons, which spreads in a prion-like manner to anatomically interconnected brain areas. However, it is not clear how α-synucleinopathy triggers neurodegeneration. We recently developed a rat model through a single intranigral administration of the neurotoxic β-sitosterol β-D-glucoside (BSSG), which produces α-synucleinopathy. In this model, we aimed to evaluate the temporal pattern of levels in oxidative and nitrosative stress and mitochondrial complex I (CI) dysfunction and how these biochemical parameters are associated with neurodegeneration in different brain areas with α-synucleinopathy (Substantia nigra pars compacta, the striatum, in the hippocampus and the olfactory bulb, where α-syn aggregation spreads). Interestingly, an increase in oxidative stress and mitochondrial CI dysfunction accompanied neurodegeneration in those brain regions. Furthermore, in silico analysis suggests a high-affinity binding site for BSSG with peroxisome proliferator-activated receptors (PPAR) alpha (PPAR-α) and gamma (PPAR-γ). These findings will contribute to elucidating the pathophysiological mechanisms associated with α-synucleinopathies and lead to the identification of new early biomarkers and therapeutic targets.

Mitochondrial protein synthesis and the bioenergetic cost of neurodevelopment

The human brain consumes five orders of magnitude more energy than the sun by unit of mass and time. This staggering bioenergetic cost serves mostly synaptic transmission and actin cytoskeleton dynamics. The peak of both brain bioenergetic demands and the age of onset for neurodevelopmental disorders is approximately 5 years of age. This correlation suggests that defects in the machinery that provides cellular energy would be causative and/or consequence of neurodevelopmental disorders. We explore this hypothesis from the perspective of the machinery required for the synthesis of the electron transport chain, an ATP-producing and NADH-consuming enzymatic cascade. The electron transport chain is constituted by nuclear- and mitochondrial-genome-encoded subunits. These subunits are synthesized by the 80S and the 55S ribosomes, which are segregated to the cytoplasm and the mitochondrial matrix, correspondingly. Mitochondrial protein synthesis by the 55S ribosome is the rate-limiting step in the synthesis of electron transport chain components, suggesting that mitochondrial protein synthesis is a bottleneck for tissues with high bionergetic demands. We discuss genetic defects in the human nuclear and mitochondrial genomes that affect these protein synthesis machineries and cause a phenotypic spectrum spanning autism spectrum disorders to neurodegeneration during neurodevelopment. We propose that dysregulated mitochondrial protein synthesis is a chief, yet understudied, causative mechanism of neurodevelopmental and behavioral disorders.

Failure of diet-induced transcriptional adaptations in alpha-synuclein transgenic mice

Nutritional influences have been discussed as potential modulators of Parkinson's disease (PD) pathology through various epidemiological and physiological studies. In animal models, a high-fat diet (HFD) with greater intake of lipid-derived calories leads to accelerated disease onset and progression. The underlying molecular mechanisms of HFD-induced aggravated pathology, however, remain largely unclear. In this study, we aimed to further illuminate the effects of a fat-enriched diet in PD by examining the brainstem and hippocampal transcriptome of alpha-synuclein transgenic mice exposed to a life-long HFD. Investigating individual transcript isoforms, differential gene expression and co-expression clusters, we observed that transcriptional differences between wild-type (WT) and transgenic animals intensified in both regions under HFD. Both brainstem and hippocampus displayed strikingly similar transcriptomic perturbation patterns. Interestingly, expression differences resulted mainly from responses in WT animals to HFD, while these genes remained largely unchanged or were even slightly oppositely regulated by diet in transgenic animals. Genes and co-expressed gene groups exhibiting this dysregulation were linked to metabolic and mitochondrial pathways. Our findings propose the failure of metabolic adaptions as the potential explanation for accelerated disease unfolding under exposure to HFD. From the identified clusters of co-expressed genes, several candidates lend themselves to further functional investigations.

Apolipoprotein A-I mimetic peptides (ApoAI MP) improve oxidative stress and inflammatory responses in Parkinson’s disease mice

Purpose: Parkinson’s disease (PD) is closely associated with oxidative stress and inflammatory situation. Apolipoprotein A-I mimetic peptides (ApoAI MP) have antioxidant and anti-inflammatory properties. We aimed to study the therapeutic effect of ApoAI MP on PD mice, and to explore the related mechanisms.

Methods: PD mice were induced by using 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP). The model mice were treated with different concentrations of ApoAI MP. The open-field behavioral test assesses the total distance moved, the rest time, and the number of crossings and Rota-rod was used to evaluate motor coordination. Oxidative stress was identified by measuring the levels of superoxide dismutase (SOD), catalase (CAT), glutathionperoxidase (GSH-Px), malondialdehyde, ROS and H2O2. Inflammatory situation was analyzed by measuring the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Meanwhile, the scavenging activities of ApoAI MP for ABTS, DPPH, hydroxyl radical and superoxide anion, and the effects of the peptide on neurotransmitters were evaluated.

Results: PD model establishment increased oxidative stress and inflammatory status by increasing the concentrations of ROS and H2O2 production, and the levels of TNF-α, IL-1β and IL-6 (p &lt; 0.05). ApoAI MP intervention improved PD symptoms by reducing the total moved distance and the number of passes (p &lt; 0.01), and the falling times from Rota-rod, and increasing rest time (p &lt; 0.05). ApoAI MP increased antioxidant properties by increasing the activities of SOD, CAT and GSH-Px, and reducing MDA concentration (p &lt; 0.05). ApoAI MP addition reduced oxidative stress by scavenging ABTS, DPPH, hydroxyl radicals and superoxide anion and reducing the concentrations of ROS and H2O2 production (p &lt; 0.05). ApoAI MP treatment increased anti-inflammatory capacities by reducing the concentrations of TNF-α, IL-1β and IL-6 (p &lt; 0.05). HPLC analysis showed that the peptide treatment improved neurotransmitters.

Conclusion: ApoAI MP can improve the behavioral performance of PD mice by improving antioxidant and anti-inflammatory capacities.

Stem cell therapy for central nervous system disorders: Metabolic interactions between transplanted cells and local microenvironments

Stem cell therapy is a promising and rapidly advancing treatment strategy for a multitude of neurologic disorders. Yet, while early phase clinical trials are being pursued in many disorders, the mechanism of action often remains unclear. One important potential mechanism by which stem cells provide neuroprotection is through metabolic signaling with diseased neurons, glia, and other cell types in the nervous system microenvironment. Early studies exploring such interactions report normalization of glucose metabolism, induction of protective mitochondrial genes, and even interactions with supportive neurovasculature. Local metabolic conditions also impact stem cell biology, which can have a large impact on transplant viability and efficacy. Epigenetic changes that occur in the donor prior to collection of stem cells, and even during in vitro culture conditions, may have effects on stem cell biology that are carried into the host upon stem cell transplantation. Transplanted stem cells also face potentially toxic metabolic microenvironments at the targeted transplant site. Novel approaches for metabolically "preconditioning" stem cells prior to transplant harness metabolic machinery to optimize stem cell survival upon transplant. Ultimately, an improved understanding of the metabolic cross-talk between implanted stem cells and the local nervous system environment, in both disease and injury states, will increase the likelihood of success in translating stem cell therapy to early trials in neurological disease.

Deregulation of ceRNA Networks in Frontal Cortex and Choroid Plexus of Brain during SARS-CoV-2 Infection Aggravates Neurological Manifestations: An Insight from Bulk and Single-Cell Transcriptomic Analyses

Although transcriptomic studies of SARS-CoV-2-infected brains have depicted variability in gene expression, the landscape of deregulated cell-specific regulatory circuits has not been elucidated yet. Hence, bulk and single-cell RNA-seq data are analyzed to gain detailed insights. Initially, two ceRNA networks with 19 and 3 differentially expressed (DE) hub lncRNAs are reconstructed in SARS-CoV-2 infected Frontal Cortex (FC) and Choroid Plexus (CP), respectively. Functional and pathway enrichment analyses of downstream mRNAs of deregulated ceRNA axes demonstrate impairment of neurological processes. Mapping of hub lncRNA-mRNA pairs from bulk RNA-seq with snRNA-seq data has indicated that NORAD, NEAT1, and STXBP5-AS1 are downregulated across 4, 4, and 2 FC cell types, respectively. At the same time, MIRLET7BHG and MALAT1 are upregulated in excitatory neurons of FC and neurons of CP, respectively. Here, it is hypothesized that downregulation of NORAD, NEAT1, and STXBP5-AS1, and upregulation of MIRLET7BHG and MALAT1 might deregulate respectively 51, 6, and 37, and 31 and 19 mRNAs in cell types of FC and CP. Afterward, 13 therapeutic miRNAs are traced that might safeguard against deregulated lncRNA-mRNA pairs of NORAD, NEAT1, and MIRLET7BHG in FC. This study helps to explain the plausible mechanism of post-COVID neurological manifestation and also to devise therapeutics against it.

Tramadol and Codeine Stacking/Boosting Dose Exposure Induced Neurotoxic Behaviors, Oxidative Stress, Mitochondrial Dysfunction, and Neurotoxic Genes in Adolescent Mice

In spite of the increasing epidemic of pharmaceutical opioids (codeine and tramadol) misuse and abuse among the adolescents, little is known about the neurotoxic consequences of the widespread practice of tramadol and codeine abuse involving increasing multiple doses across days, referred to as stacking and boosting. Hence, in this study, we replicated stacking and boosting doses of tramadol, codeine alone, or in combination on spontaneous motor activity and cognitive function in adolescent mice and adduced a plausible mechanism of possible neurotoxicity. Ninety-six adolescent mice were randomly distributed into 4 groups (n = 24 per group) and treated thrice daily for 9 days with vehicle, tramadol (20, 40, or 80 mg/kg), codeine (40, 80, or 160 mg/kg), or their combinations. Exposure of mice to tramadol induced hyperactivity and stereotypic behavior while codeine exposure caused hypoactivity and nootropic effect but tramadol-codeine cocktail led to marked reduction in spontaneous motor activity and cognitive function. In addition, tramadol, codeine, and their cocktail caused marked induction of nitroso-oxidative stress and inhibition of mitochondrial complex I activity in the prefrontal cortex (PFC) and midbrain (MB). Real-time PCR expression profiling of genes encoding neurotoxicity (RT) showed that tramadol exposure upregulate 57 and downregulate 16 neurotoxic genes, codeine upregulate 45 and downregulate 25 neurotoxic genes while tramadol-codeine cocktail upregulate 52 and downregulate 20 neurotoxic genes in the PFC. Findings from this study demonstrate that the exposure of adolescents mice to multiple and increasing doses of tramadol, codeine, or their cocktail lead to spontaneous motor coordination deficits indicative of neurotoxicity through induction of oxidative stress, inhibition of mitochondrial complex I activity and upregulation of neurotoxicity encoding genes in mice.

Cryptotanshinone ameliorates MPP+-induced oxidative stress and apoptosis of SH-SY5Y neuroblastoma cells: the role of STAT3 in Parkinson's disease

Cryptotanshinone (CTN) has shown its neuroprotective and anti-inflammatory qualities in non-genetic mouse model of Alzheimer's disease. According to bioinformatics analysis, CTN and Signal Transducer and Activator of Transcription 3 (STAT3) may interact to form a drug-target network. This study was conducted to identify the role of CTN-STAT3 interaction in Parkinson's disease (PD). PD model was established with MMP⁺-stimulated SH-SY5Y cells. After pre-treatment with CTN or co-treatment with CTN and STAT3 agonist, MTT assay was performed to observe cell viability; ELISA kit was used to measure the expression level of pro-inflammatory cytokines; DCFH-DA and corresponding assay kits were employed to determine the production of ROS, SOD, CAT and GSH-px; TUNEL assay and western blot were performed to detect cell apoptosis. STAT3 activity was also detected by western blot. Treatment with CTN alone had no impact on SH-SY5Y cell viability, but CTN pre-treatment effectively improved MPP⁺-induced loss of viability in SH-SY5Y cells. Moreover, pre-treatment with CTN inhibited MPP⁺-induced oxidative stress, apoptosis and STAT3 activity in SH-SY5Y cells, whereas this inhibitory effect was diminished after additional treatment with STAT3 agonist. CTN ameliorates MPP⁺-induced oxidative stress and apoptosis of SH-SY5Y neuroblastoma cells by inhibiting the expression of STAT3. Therefore, CTN could be a promising therapeutic agent, and STAT3 could be a potential target for PD treatment.

Increasing energy expenditure through exercise and low ambient temperature offers oxidative protection to the hypothalamus after high-fat feeding to mice

The effects of weight loss produced by increased energy expenditure on measures of oxidative stress and mitochondrial damage have not been investigated in the hypothalamus of diet-induced obese mice. The present study aimed to characterize the effects of either a low housing temperature of 17°C or daily exercise on a treadmill on high-fat diet (HFD)-induced abnormalities in the hypothalamic tissue of mice. Exercise and low ambient temperature protocols were designed to produce energy deficit through increased energy expenditure. Forty mice aged 8 weeks were assigned to one of four conditions: chow diet (n = 10), HFD (n = 10), HFD and 5 weeks of either exercise training (ET; n = 10) or an ambient temperature of 17°C (n = 10). Mice were killed at the age of 31 weeks. In comparison with HFD treatment alone, both interventions reduced body adiposity (14.6% and 27.6% reduction for the ET and 17°C groups, respectively). Moreover, exposing obese mice to ET and 17°C restored mitochondrial DNA content (41.3% and 32.6% increase for the ET and 17°C groups, respectively), decreased level of lipid peroxidation as assessed by the detection of 4-hydroxy-nonenal protein adducts (12.8% and 29.4% reduction for the ET and 17°C groups, respectively) and normalized the expression levels of proinflammatory cytokines (Tnfα: 73.9% and 62%; Il1β: 54.5% and 39.6%; Il6: 33.1% and 35.6% reduction for the ET and 17°C groups, respectively), as well as several proteins associated with mitochondrial respiratory chain (OxPhos Complex I: 75.7% and 53.9%; Complex III: 33% and 36%; Complex V: 42% and 36.9% reduction for the ET and 17°C groups, respectively) in hypothalamic cells. Negative energy balance induced through either lower ambient temperature or exercise resulted in substantial and similar improvements in markers of inflammation and mitochondrial damage in the hypothalamus of mice with diet-induced obesity, potentially by reducing oxidative stress.

Longitudinal intronic RNA-Seq analysis of Parkinson's disease patients reveals disease-specific nascent transcription

Transcriptomic studies usually focus on either gene or exon-based annotations, and only limited experiments have reported changes in reads mapping to introns. The analysis of intronic reads allows the detection of nascent transcription that is not influenced by steady-state RNA levels and provides information on actively transcribed genes. Here, we describe substantial intronic transcriptional changes in Parkinson's disease (PD) patients compared to healthy controls (CO) at two different timepoints; at the time of diagnosis (BL) and three years later (V08). We used blood RNA-Seq data from the Parkinson's Progression Markers Initiative (PPMI) cohort and identified significantly changed transcription of intronic reads only in PD patients during this follow-up period. In CO subjects, only nine transcripts demonstrated differentially expressed introns between visits. However, in PD patients, 4873 transcripts had differentially expressed introns at visit V08 compared to BL, many of them in genes previously associated with neurodegenerative diseases, such as LRRK2, C9orf72, LGALS3, KANSL1AS1, and ALS2. In addition, at the time of diagnosis (BL visit), we identified 836 transcripts (e.g. SNCA, DNAJC19, PRRG4) and at visit V08, 2184 transcripts (e.g. PINK1, GBA, ALS2, PLEKHM1) with differential intronic expression specific to PD patients. In contrast, reads mapping to exonic regions demonstrated little variation indicating highly specific changes only in intronic transcription. Our study demonstrated that PD is characterized by substantial changes in the nascent transcription, and description of these changes could help to understand the molecular pathology underpinning this disease.

Zonisamide Ameliorates Microglial Mitochondriopathy in Parkinson’s Disease Models

Mitochondrial dysfunction and exacerbated neuroinflammation are critical factors in the pathogenesis of both familial and non-familial forms of Parkinson’s disease (PD). This study aims to understand the possible ameliorative effects of zonisamide on microglial mitochondrial dysfunction in PD. We prepared 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and lipopolysaccharide (LPS) co-treated mouse models of PD to investigate the effects of zonisamide on mitochondrial reactive oxygen species generation in microglial cells. Consequently, we utilised a mouse BV2 cell line that is commonly used for microglial studies to determine whether zonisamide could ameliorate LPS-treated mitochondrial dysfunction in microglia. Flow cytometry assay indicated that zonisamide abolished microglial reactive oxygen species (ROS) generation in PD models. Extracellular flux assays showed that LPS exposure to BV2 cells at 1 μg/mL drastically reduced the mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Zonisamide overcame the inhibitory effects of LPS on mitochondrial OCR. Our present data provide novel evidence on the ameliorative effect of zonisamide against microglial mitochondrial dysfunction and support its clinical use as an antiparkinsonian drug.

Effect of Low-Dose Ionizing Radiation on the Expression of Mitochondria-Related Genes in Human Mesenchymal Stem Cells

The concept of hormesis describes a phenomenon of adaptive response to low-dose ionizing radiation (LDIR). Similarly, the concept of mitohormesis states that the adaptive program in mitochondria is activated in response to minor stress effects. The mechanisms of hormesis effects are not clear, but it is assumed that they can be mediated by reactive oxygen species. Here, we studied effects of LDIR on mitochondria in mesenchymal stem cells. We have found that X-ray radiation at a dose of 10 cGy as well as oxidized fragments of cell-free DNA (cfDNA) at a concentration of 50 ng/mL resulted in an increased expression of a large number of genes regulating the function of the mitochondrial respiratory chain complexes in human mesenchymal stem cells (MSC). Several genes remained upregulated within hours after the exposure. Both X-ray radiation and oxidized cfDNA resulted in upregulation of FIS1 and MFN1 genes, which regulated fusion and fission of mitochondria, within 3-24 h after the exposure. Three hours after the exposure, the number of copies of mitochondrial DNA in cells had increased. These findings support the hypothesis that assumes oxidized cell-free DNA as a mediator of MSC response to low doses of radiation.

Global mitochondrial protein import proteomics reveal distinct regulation by translation and translocation machinery

Most mitochondrial proteins are translated in the cytosol and imported into mitochondria. Mutations in the mitochondrial protein import machinery cause human pathologies. However, a lack of suitable tools to measure protein uptake across the mitochondrial proteome has prevented the identification of specific proteins affected by import perturbation. Here, we introduce mePROD^mt, a pulsed-SILAC based proteomics approach that includes a booster signal to increase the sensitivity for mitochondrial proteins selectively, enabling global dynamic analysis of endogenous mitochondrial protein uptake in cells. We applied mePROD^mt to determine protein uptake kinetics and examined how inhibitors of mitochondrial import machineries affect protein uptake. Monitoring changes in translation and uptake upon mitochondrial membrane depolarization revealed that protein uptake was extensively modulated by the import and translation machineries via activation of the integrated stress response. Strikingly, uptake changes were not uniform, with subsets of proteins being unaffected or decreased due to changes in translation or import capacity.

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Proteomics approach to quantify protein uptake into mitochondria

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Determination of protein uptake rates for >700 mitochondrial proteins

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Characterization of differential protein uptake changes during mitochondrial stress

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Protein translation and translocation integrate to change protein uptake

Autophagy, TERT, and mitochondrial dysfunction in hyperoxia

Ventilation with gases containing enhanced fractions of oxygen is the cornerstone of therapy for patients with hypoxia and acute respiratory distress syndrome. Yet, hyperoxia treatment increases free reactive oxygen species (ROS)-induced lung injury, which is reported to disrupt autophagy/mitophagy. Altered extranuclear activity of the catalytic subunit of telomerase, telomerase reverse transcriptase (TERT), plays a protective role in ROS injury and autophagy in the systemic and coronary endothelium. We investigated interactions between autophagy/mitophagy and TERT that contribute to mitochondrial dysfunction and pulmonary injury in cultured rat lung microvascular endothelial cells (RLMVECs) exposed in vitro, and rat lungs exposed in vivo to hyperoxia for 48 h. Hyperoxia-induced mitochondrial damage in rat lungs [TOMM20, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)], which was paralleled by increased markers of inflammation [myeloperoxidase (MPO), IL-1β, TLR9], impaired autophagy signaling (Beclin-1, LC3B-II/1, and p62), and decreased the expression of TERT. Mitochondrial-specific autophagy (mitophagy) was not altered, as hyperoxia increased expression of Pink1 but not Parkin. Hyperoxia-induced mitochondrial damage (TOMM20) was more pronounced in rats that lack the catalytic subunit of TERT and resulted in a reduction in cellular proliferation rather than cell death in RLMVECs. Activation of TERT or autophagy individually offset mitochondrial damage (MTT). Combined activation/inhibition failed to alleviate hyperoxic-induced mitochondrial damage in vitro, whereas activation of autophagy in vivo decreased mitochondrial damage (MTT) in both wild type (WT) and rats lacking TERT. Functionally, activation of either TERT or autophagy preserved transendothelial membrane resistance. Altogether, these observations show that activation of autophagy/mitophagy and/or TERT mitigate loss of mitochondrial function and barrier integrity in hyperoxia.NEW & NOTEWORTHY In cultured pulmonary artery endothelial cells and in lungs exposed in vivo to hyperoxia, autophagy is activated, but clearance of autophagosomes is impaired in a manner that suggests cross talk between TERT and autophagy. Stimulation of autophagy prevents hyperoxia-induced decreases in mitochondrial metabolism and sustains monolayer resistance. Hyperoxia increases mitochondrial outer membrane (TOMM20) protein, decreases mitochondrial function, and reduces cellular proliferation without increasing cell death.

Two hit mitochondrial-driven model of synapse loss in neurodegeneration

In healthy neurons, a mitochondrial membrane potential gradient exists whereby membrane potential is highest in the soma and decreases with distance from the nucleus. Correspondingly, distal mitochondria have more oxidative damage and slower protein import than somal mitochondria. Due to these differences, distal mitochondria have an intrinsic first stressor that somal mitochondria do not have, resulting in synaptic mitochondrial vulnerability. A second stressor may result from mutant protein expression, situational stress, or aging, exacerbating vulnerable mitochondria activating stress responses. Under these conditions, distal mitochondria release cytochrome c and mitochondrial DNA, leading to compartmentalized sub-lethal caspase-3 activation and cytokine production. In this two-hit mitochondrial-driven synaptic loss model, synapse vulnerability during neurodegeneration is explained as a superposition of pre-existing lower synaptic mitochondrial membrane potential (hit one) with additional mitochondrial stress (hit two). This two-hit mechanism occurs in synaptic mitochondria, activating signaling pathways leading to synaptic degeneration, as a potential preamble to neuronal death.

Korean red ginseng decreases 1-methyl-4-phenylpyridinium-induced mitophagy in SH-SY5Y cells

OBJECTIVE

Mitophagy is known to contribute towards progression of Parkinson's disease. Korean red ginseng (KRG) is a widely used medicinal herb in East Asia, and recent studies have reported that KRG prevents 1-methyl-4-phenylpyridinium ion (MPP⁺)-induced cell death. This study was undertaken to investigate whether KRG suppresses MPP⁺-induced apoptosis and mitophagy.

METHODS

SH-SY5Y cells were incubated with KRG for 24 h, and subsequently exposed to MPP⁺. The MPP⁺-induced cell death was confirmed with the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, and the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay. Changes in the structure and function of mitochondria were confirmed using mitotracker, MitoSOX red mitochondrial superoxide indicator, parkin, and phosphatase and tensin homolog deleted on chromosome ten-induced putative kinase 1 (PINK1) immunofluorescent staining. Western blotting was performed to evaluate the expression of apoptosis-related factors in whole cells, including Bax, Bcl-2 and cleaved caspase-3, and mitophagy-related factors in the mitochondrial fraction, including cytochrome c, parkin, PINK1, translocase of the outer membrane 20 (TOM20), p62 and Beclin 1.

RESULTS

MPP⁺ induced cell death by cytochrome c release and caspase-3 activation; however, this effect was suppressed by KRG's regulation of the expressions of Bcl-2 and Bax. Moreover, MPP⁺ exposure increased the mitochondrial expressions of parkin, PINK1, Beclin 1 and p62, and decreased TOM20, cytochrome c and Bcl-2 expressions. These MPP⁺-induced changes in the mitochondrial fraction were attenuated by treatment with KRG.

CONCLUSION

KRG effectively prevents MPP⁺-induced SH-SY5Y cell death by regulating cytochrome c release from mitochondria and PINK1/parkin-mediated mitophagy, through regulation of the Bcl-2 family.

Neuronal mitochondrial dysfunction in sporadic amyotrophic lateral sclerosis is developmentally regulated

Amyotrophic lateral sclerosis is an adult-onset neurodegenerative disorder characterized by loss of motor neurons. Mitochondria are essential for neuronal survival but the developmental timing and mechanistic importance of mitochondrial dysfunction in sporadic ALS (sALS) neurons is not fully understood. We used human induced pluripotent stem cells and generated a developmental timeline by differentiating sALS iPSCs to neural progenitors and to motor neurons and comparing mitochondrial parameters with familial ALS (fALS) and control cells at each developmental stage. We report that sALS and fALS motor neurons have elevated reactive oxygen species levels, depolarized mitochondria, impaired oxidative phosphorylation, ATP loss and defective mitochondrial protein import compared with control motor neurons. This phenotype develops with differentiation into motor neurons, the affected cell type in ALS, and does not occur in the parental undifferentiated sALS cells or sALS neural progenitors. Our work demonstrates a developmentally regulated unifying mitochondrial phenotype between patient derived sALS and fALS motor neurons. The occurrence of a unifying mitochondrial phenotype suggests that mitochondrial etiology known to SOD1-fALS may applicable to sALS. Furthermore, our findings suggest that disease-modifying treatments focused on rescue of mitochondrial function may benefit both sALS and fALS patients.