Search Results (83)

Neuroinflammation is the major contributor to the pathology of neonatal hypoxic–ischemic (HI) brain injury. Our previous studies have demonstrated that microRNA210 (miR210) inhibition with antisense locked nucleic acid (LNA) inhibitor mitigates neuroinflammation and provides neuroprotection after neonatal HI insult. However, the underlying mechanisms remain elusive. In the present study, using miR210 knockout (KO) mice and microglial cultures, we tested the hypothesis that miR210 promotes microglial activation and neuroinflammation through suppressing mitochondrial function in microglia after HI. Neonatal HI brain injury was conducted on postnatal day 9 (P9) wild-type (WT) and miR210 knockout (KO) mouse pups. We found that miR210 KO significantly reduced brain infarct size at 48 h and improved long-term locomotor functions assessed by an open field test three weeks after HI. Moreover, miR210 KO mice exhibited reduced IL1β levels, microglia activation and immune cell infiltration after HI. In addition, in vitro studies of microglia exposed to oxygen–glucose deprivation (OGD) revealed that miR210 inhibition with LNA reduced OGD-induced expression of Il1β and rescued OGD-mediated downregulation of mitochondrial iron–sulfur cluster assembly enzyme (ISCU) and mitochondrial oxidative phosphorylation activity. To validate the link between miR210 and microglia activation, isolated primary murine microglia were transfected with miR210 mimic or negative control. The results showed that miR210 mimic downregulated the expression of mitochondrial ISCU protein abundance and induced the expression of proinflammatory cytokines similar to the effect observed with ISCU silencing RNA. In summary, our results suggest that miR210 is a key regulator of microglial proinflammatory activation through reprogramming mitochondrial function in neonatal HI brain injury. Full article

Type 10 17β-hydroxysteroid dehydrogenase (17β-HSD10) is the HSD17B10 gene product. It plays an appreciable part in the carcinogenesis and pathogenesis of neurodegeneration, such as Alzheimer’s disease and infantile neurodegeneration. This mitochondrial, homo-tetrameric protein is a central hub in various metabolic pathways, e.g., branched-chain amino acid degradation and neurosteroid metabolism. It can bind to other proteins carrying out diverse physiological functions, e.g., tRNA maturation. It has also previously been proposed to be an Aβ-binding alcohol dehydrogenase (ABAD) or endoplasmic reticulum-associated Aβ-binding protein (ERAB), although those reports are controversial due to data analyses. For example, the reported k_m value of some substrate of ABAD/ERAB was five times higher than its natural solubility in the assay employed to measure k_m. Regarding any reported “one-site competitive inhibition” of ABAD/ERAB by Aβ, the k_i value estimations were likely impacted by non-physiological concentrations of 2-octanol at high concentrations of vehicle DMSO and, therefore, are likely artefactual. Certain data associated with ABAD/ERAB were found not reproducible, and multiple experimental approaches were undertaken under non-physiological conditions. In contrast, 17β-HSD10 studies prompted a conclusion that Aβ inhibited 17β-HSD10 activity, thus harming brain cells, replacing a prior supposition that “ABAD” mediates Aβ neurotoxicity. Furthermore, it is critical to find answers to the question as to why elevated levels of 17β-HSD10, in addition to Aβ and phosphorylated Tau, are present in the brains of AD patients and mouse AD models. Addressing this question will likely prompt better approaches to develop treatments for Alzheimer’s disease. Full article

Cocaine misuse induces microglial activation and neuroinflammation, contributing to neurodegeneration and behavioral impairments. Prior studies have shown that cocaine induces mitochondrial dysfunction, dysregulated mitophagy, and lysosomal impairment in microglia. Here, we investigated the therapeutic potential of N-acetylcysteine (NAC) in mitigating cocaine-induced microglial activation and neuroinflammation. Mouse primary microglial cells (MPMs) were pretreated with NAC (5 mM) for 1 h prior to cocaine exposure (10 µM, 24 h) and analyzed for markers of microglial activation, mitophagy, and lysosomal integrity using Western blot, Seahorse assays, lysosomal pH, and membrane potential measurements. In vivo, C57BL/6N mice received NAC (200 mg/kg, i.p.) 1 h before daily cocaine injections (20 mg/kg, i.p.) for 7 days. Behavioral assays (open field, novel object recognition) and brain biomarker analyses (frontal cortex, hippocampus) were performed. Cocaine exposure elevated CD11b, mitophagy markers (PINK1, PARK, and DLP1), and autophagy proteins (Beclin1, and p62), while impairing mitochondrial and lysosomal functions. NAC pretreatment restored mitochondrial and lysosomal function, reduced reactive oxygen species, and normalized protein expression. In vivo, NAC also alleviated cocaine-induced microglial activation and behavioral deficits. These findings highlight NAC as a promising therapeutic agent to counteract cocaine-mediated neuroinflammation and neurotoxicity. Full article

In this study, we assessed the ability of 2-Cl-MGV-1 (2-chlorophenyl quinazolin-4-yl, dimethyl carbamate), a ligand of the 18 kDa mitochondrial translocator protein (TSPO), to mitigate brain damage in a mouse model of traumatic brain injury (TBI). TSPO is important for arresting the death of neurons and glia and counteracting microglial activation, and it provides anti-inflammatory activity, promotes regeneration (including neurons), and contributes to angiogenesis. We assessed the minimal dose of the TSPO ligand 2-Cl-MGV-1 that attenuates the magnitude of brain damage as well as the time window following TBI in which the treatment is effective. We found that 7.5 mg/kg of 2-Cl-MGV-1 can reduce the impact of the TBI as assessed by magnetic resonance imaging (MRI). We also found that 2-Cl-MGV-1 improved motor performance as observed in a treadmill test (80.9% fewer shocks needed and 40.7% more distance covered, both p < 0.05), and reduced anatomical brain damage (by 86.5%, p < 0.05), cell death (by 75.0%, p < 0.001), and microglial inflammatory response (by 50.2%, p < 0.01). The treatment also increased expression of neuronal markers NeuN and β3-tubulin (30.0%, p < 0.01; 36.0%, p < 0.01, respectively). The time window in which we found the treatment to be effective was 3–11 h after TBI. Our study suggests that agents active at the TSPO can significantly attenuate the outcome of TBI, including in the structural, cellular, and neuro-behavioral dimensions. The mechanisms involved in the attenuation of brain damage following TBI may be related to a decrease in cell death and to anti-inflammatory activity. TSPO seems to be a novel target for the development of agents aimed at the suppression of neurodegenerative processes. Full article

We explored how the phosphorylation state of collapsin response mediator protein 2 (CRMP2) influences mitochondrial functions in cultured cortical neurons and cortical synaptic mitochondria isolated from APP-SAA KI mice, a knock-in APP mouse model of Alzheimer’s disease (AD). CRMP2 phosphorylation was increased at Thr 509/514 and Ser 522 in brain cortical lysates and cultured neurons from AD mice. The basal and maximal respiration of AD neurons were decreased. Mitochondria were hyperpolarized and superoxide anion production was increased in neurons from AD mice. In isolated synaptic AD mitochondria, ADP-stimulated and DNP-stimulated respiration were decreased, whereas ADP-induced mitochondrial depolarization was reduced and prolonged. We found that CRMP2 binds to the adenine nucleotide translocase (ANT) in a phosphorylation-dependent manner. The increased CRMP2 phosphorylation in AD mice correlated with CRMP2 dissociation from the ANT and decreased ANT activity in AD mitochondria. On the other hand, recombinant CRMP2 (rCRMP2), added to the ANT-reconstituted proteoliposomes, increased ANT activity. A small molecule (S)-lacosamide ((S)-LCM), which binds to CRMP2 and suppresses CRMP2 phosphorylation by Cdk5 and GSK-3β, prevented CRMP2 hyperphosphorylation, rescued CRMP2 binding to the ANT, improved ANT activity, and restored the mitochondrial membrane potential and respiratory responses to ADP and 2,4-dinitrophenol. Thus, our study highlights an important role for CRMP2 in regulating the mitochondrial oxidative metabolism in AD by modulating the ANT activity in a phosphorylation-dependent manner. Full article

Background/Objectives: Parkinson’s disease (PD) is a rapidly growing neurological disorder in the developed world, affecting millions over the age of 60. The decline in motor functions occurs due to a progressive loss of midbrain dopaminergic neurons, resulting in lowered dopamine levels and impaired muscle function. Studies show defective mitochondrial autophagy (or “mitophagy”) links to PD. Rho-associated coiled-coil containing protein kinases (ROCK) 1 and ROCK2 are serine/threonine kinases, and their inhibition can enhance neuroprotection in PD by promoting mitophagy. Methods: We examine the effects of ROCK inhibitor SR3677, delivered via macrophage-derived small extracellular vesicles (sEVs) to Parkin Q311X(A) PD mouse models. sEVs with SR3677, administered intranasally, increased mitophagy gene expression, reduced inflammatory factors, and elevated dopamine levels in brain tissues. Results: ROCK2 expression decreased, showing the drug’s inhibitory effect. sEV-SR3677 treatment was more effective than treatment with the drug alone, although sham EVs showed lower effects. This suggests that EV-SR3677 not only activates mitochondrial processes but also promotes the degradation of damaged mitochondria through autophagy. Mitochondrial functional assays and oxygen consumption in ex vivo glial cultures revealed that sEV-SR3677 significantly improved mitochondrial respiration compared to that in untreated or SR3677-only treated cells. Conclusion: We demonstrated the efficacy of ROCK2 inhibition on mitochondrial function via sEV-SR3677 in the PD mouse model, necessitating further studies to explore design challenges and mechanisms of sEV-SR3677 as mitochondria-targeted therapy for PD Full article

The tRNA epitranscriptome has been recognized as an important player in mRNA translation regulation. Our knowledge of the role of the tRNA epitranscriptome in fine-tuning translation via codon decoding at tissue or cell levels remains incomplete. We analyzed tRNA expression and modifications as well as codon optimality across seven mouse tissues. Our analysis revealed distinct enrichment patterns of tRNA modifications in different tissues. Queuosine (Q) tRNA modification was most enriched in the brain compared to other tissues, while mitochondrial tRNA modifications and tRNA expression were highest in the heart. Using this observation, we synthesized, and delivered in vivo, codon-mutated EGFP for Q-codons, where the C-ending Q-codons were replaced with U-ending codons. The protein levels of mutant EGFP were downregulated in liver, which is poor in Q, while in brain EGFP, levels did not change. These data show that understanding tRNA modification enrichments across tissues is not only essential for understanding codon decoding and bias but can also be utilized for optimizing gene and mRNA therapeutics to be more tissue-, cell-, or condition-specific. Full article

Emphasizing their evolutionarily conserved role in stress adaptation mechanisms, ribosomal protein genes (RPGs) are observed to be downregulated in various stressors and across phyla. However, this evolutionarily conserved stress response is not well explored in mouse models of neurobiological stress. This study investigates the dysregulation patterns of RPGs in various murine preclinical stress paradigms across different brain regions using available transcriptomic data and identifies the non-canonical ribosomal functions using synaptic gene-ontology terms. Without a discernible structure across different brain areas, we observed heterogeneous dysregulation, encompassing either up or downregulation in both cytoplasmic and mitochondrial RPGs. However, downregulation was more prominent than upregulation, and the overall dysregulation seems more prevalent in the chronic stress paradigm compared to stress paradigms involving acute and early-life stress. Enrichment analysis significantly associates dysregulated RPGs with post-synaptic gene ontology terms, emphasizing their involvement in synaptic modulation. Overall, the study demonstrates ribosomal dysregulation as an evolutionarily conserved stress response mechanism during different mouse stress paradigms. We discuss the possibility that the variability in the directionality of dysregulation may emerge as a potential marker of neuronal activity in response to diverse stress paradigms and the involvement of paradigm-specific RPG dysregulation either in the process of global downscaling of ribosome biogenesis or in the process of ribosomal heterogeneity, each leading to a different effect. Full article

This study aimed to explore the intricate relationship between mitochondrial dysfunction, infection, and neuroinflammation, focusing specifically on the impact of pathogenic epitopes of the Epstein–Barr Virus (EBV) nuclear antigen 1 (EBNA1) in a mouse model of mitochondrial dysfunctions. The investigation included female middle-aged PARK2^−/− and C57BL/6J wild-type mice immunized with EBNA1_386–405 or with active experimental autoimmune encephalomyelitis (EAE) induction by the myelin oligodendrocyte glycoprotein (MOG)_35–55 peptide. The PARK2^−/− mice developed more severe EAE than the wild-type mice. Following immunization with EBNA1_386–405, only PARK2^−/− exhibited symptoms resembling EAE. During the acute phase, PARK2^−/− mice immunized with either MOG_35–55 or EBNA1_386–405 exhibited a similar infiltration of the T cells and macrophages in the spinal cord and decreased glial fibrillary acidic protein (GFAP) expression in the brain. However, the EBNA1_386–405 -immunized PARK2^−/− mice showed significantly increased frequencies of CD8a⁺ T cells and CD11c⁺ B cells, and distinct cytokine profiles in the periphery compared to the wild-type controls. These findings highlight the role of EBV in exacerbating inflammation, particularly in the context of mitochondrial deficiencies. Full article

Background/Objectives: Aging has been extensively studied, with a growing interest in memory impairment by a neurobiological approach. Mitochondrial dysfunction is a hallmark of aging, contributing to the aging phenotype; therefore, mitochondrial interventions seem fundamental. The diet is a physiological approximation for modifying mitochondria, which could impact the age-related phenotype. Methods: We studied two diets with low-carbohydrate and high-fat compositions, differing in the amount of protein and the fat type disposable—the atherogenic diet Cocoa (high protein/high saturated fat/high cholesterol) and the South Beach diet (very high-protein/high-unsaturated fat)—on oxidative stress, mitochondrial state, and hippocampus-dependent memory in 3-month-old Senescence-Accelerated Mouse Model (SAMP8) seed over 3 months to determine their pro- or anti-aging effects. Results: Despite its bad reputation, the Cocoa diet reduces the reactive oxygen species (ROS) content without impacting the energy state and hippocampus-dependent spatial acuity. In contrast to the beneficial impact proposed for the South Beach diet, it induced a pro-aging phenotype, increasing oxidative damage and the levels of NR2B subunit of the NMDA, impairing energy and spatial acuity. Surprisingly, despite the negative changes observed with both diets, this led to subtle memory impairment, suggesting the activation of compensatory mechanisms preventing more severe cognitive decline. Conclusions: Our results demonstrated that diets usually considered good could be detrimental to the onset of aging. Also, probably due to the brain plasticity of non-aged animals, they compensate for the damage, preventing a more aggravated phenotype. Nevertheless, these silent changes could predispose or increase the risk of suffering pathologies at advanced age. Full article

Mitochondrial quality control is essential in mitochondrial function. To examine the importance of Parkin-dependent mechanisms in mitochondrial quality control, we assessed the impact of modulating Parkin on proteome flux and mitochondrial function in a context of reduced mtDNA fidelity. To accomplish this, we crossed either the Parkin knockout mouse or ParkinW402A knock-in mouse lines to the Polg mitochondrial mutator line to generate homozygous double mutants. In vivo longitudinal isotopic metabolic labeling was followed by isolation of liver mitochondria and synaptic terminals from the brain, which are rich in mitochondria. Mass spectrometry and bioenergetics analysis were assessed. We demonstrate that slower mitochondrial protein turnover is associated with loss of mtDNA fidelity in liver mitochondria but not synaptic terminals, and bioenergetic function in both tissues is impaired. Pathway analysis revealed loss of mtDNA fidelity is associated with disturbances of key metabolic pathways, consistent with its association with metabolic disorders and neurodegeneration. Furthermore, we find that loss of Parkin leads to exacerbation of Polg-driven proteomic consequences, though it may be bioenergetically protective in tissues exhibiting rapid mitochondrial turnover. Finally, we provide evidence that, surprisingly, dis-autoinhibition of Parkin (ParkinW402A) functionally resembles Parkin knockout and fails to rescue deleterious Polg-driven effects. Our study accomplishes three main outcomes: (1) it supports recent studies suggesting that Parkin dependence is low in response to an increased mtDNA mutational load, (2) it provides evidence of a potential protective role of Parkin insufficiency, and (3) it draws into question the therapeutic attractiveness of enhancing Parkin function. Full article

Mitochondrial aldehyde dehydrogenase-2 (ALDH2) metabolizes acetaldehyde to acetate. People with ALDH2 deficiency and Aldh2-knockout (KO) mice are more susceptible to alcohol-induced tissue damage. However, the underlying mechanisms behind ALDH2-related gut-associated brain damage remain unclear. Age-matched young female Aldh2-KO and C57BL/6J wild-type (WT) mice were gavaged with binge alcohol (4 g/kg/dose, three doses) or dextrose (control) at 12 h intervals. Tissues and sera were collected 1 h after the last ethanol dose and evaluated by histological and biochemical analyses of the gut and hippocampus and their extracts. For the mechanistic study, mouse neuroblast Neuro2A cells were exposed to ethanol with or without an Aldh2 inhibitor (Daidzin). Binge alcohol decreased intestinal tight/adherens junction proteins but increased oxidative stress-mediated post-translational modifications (PTMs) and enterocyte apoptosis, leading to elevated gut leakiness and endotoxemia in Aldh2-KO mice compared to corresponding WT mice. Alcohol-exposed Aldh2-KO mice also showed higher levels of hippocampal brain injury, oxidative stress-related PTMs, and neuronal apoptosis than the WT mice. Additionally, alcohol exposure reduced Neuro2A cell viability with elevated oxidative stress-related PTMs and apoptosis, all of which were exacerbated by Aldh2 inhibition. Our results show for the first time that ALDH2 plays a protective role in binge alcohol-induced brain injury partly through the gut–brain axis, suggesting that ALDH2 is a potential target for attenuating alcohol-induced tissue injury. Full article

Down syndrome (DS) is the most common form of inherited intellectual disability caused by trisomy of chromosome 21, presenting with intellectual impairment, craniofacial abnormalities, cardiac defects, and gastrointestinal disorders. The Ts65Dn mouse model replicates many abnormalities of DS. We hypothesized that investigation of the cerebral cortex of fluoxetine-treated trisomic mice may provide proteomic signatures that identify therapeutic targets for DS. Subcellular fractionation of synaptosomes from cerebral cortices of age- and brain-area-matched samples from fluoxetine-treated vs. water-treated trisomic and euploid male mice were subjected to HPLC-tandem mass spectrometry. Analysis of the data revealed enrichment of trisomic risk genes that participate in regulation of synaptic vesicular traffic, pre-synaptic and post-synaptic development, and mitochondrial energy pathways during early brain development. Proteomic analysis of trisomic synaptic fractions revealed significant downregulation of proteins involved in synaptic vesicular traffic, including vesicular endocytosis (CLTA, CLTB, CLTC), synaptic assembly and maturation (EXOC1, EXOC3, EXOC8), anterograde axonal transport (EXOC1), neurotransmitter transport to PSD (SACM1L), endosomal-lysosomal acidification (ROGDI, DMXL2), and synaptic signaling (NRXN1, HIP1, ITSN1, YWHAG). Additionally, trisomic proteomes revealed upregulation of several trafficking proteins, involved in vesicular exocytosis (Rab5B), synapse elimination (UBE3A), scission of endocytosis (DBN1), transport of ER in dendritic spines (MYO5A), presynaptic activity-dependent bulk endocytosis (FMR1), and NMDA receptor activity (GRIN2A). Chronic fluoxetine treatment of Ts65Dn mice rescued synaptic vesicular abnormalities and prevented abnormal proteomic changes in adult Ts65Dn mice, pointing to therapeutic targets for potential treatment of DS. Full article

Traumatic brain injury (TBI) can lead to post-traumatic epilepsy (PTE). Blast TBI (bTBI) found in Veterans presents with several complications, including cognitive and behavioral disturbances and PTE; however, the underlying mechanisms that drive the long-term sequelae are not well understood. Using an unbiased proteomics approach in a mouse model of repeated bTBI (rbTBI), this study addresses this gap in the knowledge. After rbTBI, mice were monitored using continuous, uninterrupted video-EEG for up to four months. Following this period, we collected cortex and hippocampus tissues from three groups of mice: those with post-traumatic epilepsy (PTE⁺), those without epilepsy (PTE⁻), and the control group (sham). Hundreds of differentially expressed proteins were identified in the cortex and hippocampus of PTE⁺ and PTE⁻ relative to sham. Focusing on protein pathways unique to PTE⁺, pathways related to mitochondrial function, post-translational modifications, and transport were disrupted. Computational metabolic modeling using dysregulated protein expression predicted mitochondrial proton pump dysregulation, suggesting electron transport chain dysregulation in the epileptic tissue relative to PTE⁻. Finally, data mining enabled the identification of several novel and previously validated TBI and epilepsy biomarkers in our data set, many of which were found to already be targeted by drugs in various phases of clinical testing. These findings highlight novel proteins and protein pathways that may drive the chronic PTE sequelae following rbTBI. Full article

Alzheimer’s disease (AD) is a representative cause of dementia and is caused by neuronal loss, leading to the accumulation of aberrant neuritic plaques and the formation of neurofibrillary tangles. Oxidative stress is involved in the impaired clearance of amyloid beta (Aβ), and Aβ-induced oxidative stress causes AD by inducing the formation of neurofibrillary tangles. Hwangryunhaedok-tang (HHT, Kracie K-09^®), a traditional herbal medicine prescription, has shown therapeutic effects on various diseases. However, the studies of HHT as a potential treatment for AD are insufficient. Therefore, our study identified the neurological effects and mechanisms of HHT and its key bioactive compounds against Alzheimer’s disease in vivo and in vitro. In a 5xFAD mouse model, our study confirmed that HHT attenuated cognitive impairments in the Morris water maze (MWM) test and passive avoidance (PA) test. In addition, the prevention of neuron impairment, reduction in the protein levels of Aβ, and inhibition of cell apoptosis were confirmed with brain tissue staining. In HT-22 cells, HHT attenuates tBHP-induced cytotoxicity, ROS generation, and mitochondrial dysfunction. It was verified that HHT exerts a neuroprotective effect by activating signaling pathways interacting with Nrf2, such as MAPK/ERK, PI3K/Akt, and LKB1/AMPK. Among the components, baicalein, a bioavailable compound of HHT, exhibited neuroprotective properties and activated the Akt, AMPK, and Nrf2/HO-1 pathways. Our findings indicate a mechanism for HHT and its major bioavailable compounds to treat and prevent AD and suggest its potential. Full article