Overexpression of COX6B1 protects against I/R‑induced neuronal injury in rat hippocampal neurons

Transcriptomic analysis reveals mitochondrial pathways associated with distinct adolescent behavioral phenotypes and stress response

Adolescent individuals exhibit great variability in cortical dynamics and behavioral outcomes. The developing adolescent brain is highly sensitive to social experiences and environmental insults, influencing how personality traits emerge. A distinct pattern of mitochondrial gene expression in the prefrontal cortex (PFC) during adolescence underscores the essential role of mitochondria in brain maturation and the development of mental illnesses. Mitochondrial features in certain brain regions account for behavioral differences in adulthood. However, it remains unclear whether distinct adolescent behavioral phenotypes and the behavioral consequences of early adolescent stress exposure in rats are accompanied by changes in PFC mitochondria-related genes and mitochondria respiratory chain capacity. We performed a behavioral characterization during late adolescence (postnatal day, PND 47-50), including naïve animals and a group exposed to stress from PND 31-40 (10 days of footshock and 3 restraint sessions) by z-normalized data from three behavioral domains: anxiety (light-dark box tests), sociability (social interaction test) and cognition (novel-object recognition test). Employing principal component analysis, we identified three clusters: naïve with higher-behavioral z-score (HBZ), naïve with lower-behavioral z-score (LBZ), and stressed animals. Genome-wide transcriptional profiling unveiled differences in the expression of mitochondria-related genes in both naïve LBZ and stressed animals compared to naïve HBZ. Genes encoding subunits of oxidative phosphorylation complexes were significantly down-regulated in both naïve LBZ and stressed animals and positively correlated with behavioral z-score of phenotypes. Our network topology analysis of mitochondria-associated genes found Ndufa10 and Cox6a1 genes as central identifiers for naïve LBZ and stressed animals, respectively. Through high-resolution respirometry analysis, we found that both naïve LBZ and stressed animals exhibited a reduced prefrontal phosphorylation capacity and redox dysregulation. Our findings identify an association between mitochondrial features and distinct adolescent behavioral phenotypes while also underscoring the detrimental functional consequences of adolescent stress on the PFC.

Chinese herbal formula (GCNY)-medicated serum alleviates peroxidation induced by H2O2 in human microglial cells

Traditional Chinese herbal medicine aiming at nourishing yin formed a distinctive school of thought in history to achieve anti-aging and longevity. In the formula Gancao nourishing yin (GCNY) decoction, all of the ingredients show antioxidant properties. However, in real clinical practice, extractions of herbs are rarely applied alone but are prescribed as the integrated formula. To investigate whether GCNY possesses anti-oxidation potential, we applied GCNY to treat rats to acquire medicated serum, which was then added on H₂O₂ (200 μM)-modeled human microglial cell line HMC-3 in comparison with its control serum. The results revealed that GCNY-medicated serum decreased reactive oxygen species (ROS) levels. Inflammatory cytokines such as pNF-κB p65 (ser536) and IL-6 were also decreased. Nrf2 and its pathway-related molecules, such as HO1, ABCC2, GLCM, ME1, NQO1, and TKT, were activated by H₂O₂ modeling while declined by treating with GCNY-medicated serum, which indicated attenuated oxidative stress of GCNY. Furthermore, mRNA-seq analysis showed 58 differential expressed genes (DEGs), which were enriched in pathways including antigen processing and presentation, longevity regulation, oxidative phosphorylation, and Parkinson’s disease progression. DEGs that were downregulated by H₂O₂ modeling but upregulated by GCNY treatment include CENPF, MKI67, PRR11, and TOP2A. Those targets were reported to be associated with the cell cycle and cell proliferation and belong to the category of growth factor genes. In conclusion, this study verified anti-oxidation effects of GCNY and indicated its promising application for cognitive degeneration and aging-related disorders.

Mutations in the Yeast Cox12 Subunit Severely Compromise the Activity of the Mitochondrial Complex IV

Cytochrome c oxidase 6B1 (COX6B1) is one of the less characterized subunits of the mitochondrial electron transport chain complex IV (CIV). Here, we studied the pathobiochemical and respiratory functions of Cox12 (yeast ortholog of COX6B1) using Saccharomyces cerevisiae BY4741 (cox12Δ) cells deficient by the Cox12 protein. The cells exhibited severe growth deficiency in the respiratory glycerol-ethanol medium, which could be reverted by complementation with the yeast COX12 or human COX6B1 genes. Cox12 with arginine 17 residue substituted by histidine (R17H) or cysteine (R17C) (mutations analogous to those observed in human patients) failed to complement the loss of Cox12 function. When cox12Δ cells were grown in rich respiratory/fermentative galactose medium, no changes in the expression of individual respiratory chain subunits were observed. Blue native PAGE/Western blotting analysis using antibodies against Rip1 and Cox1, which are specific components of complexes III (CIII) and IV (CIV), respectively, revealed no noticeable decrease in the native CIII₂CIV₂ and CIII₂CIV₁ supercomplexes (SCs). However, the association of the respiratory SC factor 2 (Rcf2) and Cox2 subunit within the SCs of cox12Δ cells was reduced, while the specific activity of CIV was downregulated by 90%. Both basal respiration and succinate-ADP stimulated state 3 respiration, as well as the mitochondrial membrane potential, were decreased in cox12Δ cells. Furthermore, cox12Δ cells and cells synthesizing Cox12 mutants R17H and R17C showed higher sensitivity to the H2O2-induced oxidative stress compared to the wild-type (WT) cells. In silico structural modeling of the WT yeast SCs revealed that Cox12 forms a network of interactions with Rcf2 and Cox2. Together, our results establish that Cox12 is essential for the CIV activity.

Suppression of a core metabolic enzyme dihydrolipoamide dehydrogenase (dld) protects against amyloid beta toxicity in C. elegans model of Alzheimer's disease

A decrease in energy metabolism is associated with Alzheimer's disease (AD), but it is not known whether the observed decrease exacerbates or protects against the disease. The importance of energy metabolism in AD is reinforced by the observation that variants of dihydrolipoamide dehydrogenase (DLD), is genetically linked to late-onset AD. To determine whether DLD is a suitable therapeutic target, we suppressed the dld-1 gene in Caenorhabditis elegans that express human Aβ peptide in either muscles or neurons. Suppression of the dld-1 gene resulted in significant restoration of vitality and function that had been degraded by Aβ pathology. This included protection of neurons and muscles cells. The observed decrease in proteotoxicity was associated with a decrease in the formation of toxic oligomers rather than a decrease in the abundance of the Aβ peptide. The mitochondrial uncoupler, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), which like dld-1 gene expression inhibits ATP synthesis, had no significant effect on Aβ toxicity. Proteomics data analysis revealed that beneficial effects after dld-1 suppression could be due to change in energy metabolism and activation of the pathways associated with proteasomal degradation, improved cell signaling and longevity. Thus, some features unique to dld-1 gene suppression are responsible for the therapeutic benefit. By direct genetic intervention, we have shown that acute inhibition of dld-1 gene function may be therapeutically beneficial. This result supports the hypothesis that lowering energy metabolism protects against Aβ pathogenicity and that DLD warrants further investigation as a therapeutic target.

Gut microbial taxa elevated by dietary sugar disrupt memory function

Emerging evidence highlights a critical relationship between gut microbiota and neurocognitive development. Excessive consumption of sugar and other unhealthy dietary factors during early life developmental periods yields changes in the gut microbiome as well as neurocognitive impairments. However, it is unclear whether these two outcomes are functionally connected. Here we explore whether excessive early life consumption of added sugars negatively impacts memory function via the gut microbiome. Rats were given free access to a sugar-sweetened beverage (SSB) during the adolescent stage of development. Memory function and anxiety-like behavior were assessed during adulthood and gut bacterial and brain transcriptome analyses were conducted. Taxa-specific microbial enrichment experiments examined the functional relationship between sugar-induced microbiome changes and neurocognitive and brain transcriptome outcomes. Chronic early life sugar consumption impaired adult hippocampal-dependent memory function without affecting body weight or anxiety-like behavior. Adolescent SSB consumption during adolescence also altered the gut microbiome, including elevated abundance of two species in the genus Parabacteroides (P. distasonis and P. johnsonii) that were negatively correlated with hippocampal function. Transferred enrichment of these specific bacterial taxa in adolescent rats impaired hippocampal-dependent memory during adulthood. Hippocampus transcriptome analyses revealed that early life sugar consumption altered gene expression in intracellular kinase and synaptic neurotransmitter signaling pathways, whereas Parabacteroides microbial enrichment altered gene expression in pathways associated with metabolic function, neurodegenerative disease, and dopaminergic signaling. Collectively these results identify a role for microbiota "dysbiosis" in mediating the detrimental effects of early life unhealthy dietary factors on hippocampal-dependent memory function.

Multiple Mechanisms Regulate Eukaryotic Cytochrome C Oxidase

Cytochrome c oxidase (COX), the rate-limiting enzyme of mitochondrial respiration, is regulated by various mechanisms. Its regulation by ATP (adenosine triphosphate) appears of particular importance, since it evolved early during evolution and is still found in cyanobacteria, but not in other bacteria. Therefore the "allosteric ATP inhibition of COX" is described here in more detail. Most regulatory properties of COX are related to "supernumerary" subunits, which are largely absent in bacterial COX. The "allosteric ATP inhibition of COX" was also recently described in intact isolated rat heart mitochondria.

The protective effects of curcumin in cerebral ischemia and reperfusion injury through PKC-θ signaling

Ischemic stroke is a common cerebrovascular disease with the main cause considered to be cerebral ischemia and reperfusion (I/R), which exerts irreparable injury on nerve cells. Thus, the development of neuroprotective drugs is an urgent concern. Curcumin, a known antioxidant, has been found to have neuroprotective effects. To determine the protective mechanism of curcumin in ischemic stroke, oxygen and glucose deprivation/reoxygenation (OGD/R) was used to treat PC12 cells to mimic the cerebral I/R cell model. Curcumin (20 μM) was applied to OGD/R PC12 cells, followed by Ca²⁺ concentration, transepithelial electrical resistance (TEER), and cell permeability measurements. The results showed that OGD/R injury induced a decrease in TEER and increases in Ca²⁺ concentration and cell permeability. In contrast, curcumin alleviated these effects. The protein kinase C θ (PKC-θ) was associated with the protective function of curcumin in the OGD/R cell model. Moreover, the middle cerebral artery occlusion and reperfusion model (MCAO/R) was applied to simulate the I/R rat model. Our results demonstrated that curcumin could reverse the MCAO/R-induced increase in Ca²⁺ concentration and blood-brain barrier (BBB) disruption. Our study demonstrates the mechanisms by which curcumin exhibited a protective function against cerebral I/R through PKC-θ signaling by reducing BBB dysfunction.

Proteomic Characterization of Proliferation Inhibition of Well-Differentiated Laryngeal Squamous Cell Carcinoma Cells Under Below-Background Radiation in a Deep Underground Environment

Background: There has been a considerable concern about cancer induction in response to radiation exposure. However, only a limited number of studies have focused on the biological effects of below-background radiation (BBR) in deep underground environments. To improve our understanding of the effects of BBR on cancer, we studied its biological impact on well-differentiated laryngeal squamous cell carcinoma cells (FD-LSC-1) in a deep underground laboratory (DUGL). Methods: The growth curve, morphological, and quantitative proteomic experiments were performed on FD-LSC-1 cells cultured in the DUGL and above-ground laboratory (AGL). Results: The proliferation of FD-LSC-1 cells from the DUGL group was delayed compared to that of cells from the AGL group. Transmission electron microscopy scans of the cells from the DUGL group indicated the presence of hypertrophic endoplasmic reticulum (ER) and a higher number of ER. At a cutoff of absolute fold change ≥ 1.2 and p < 0.05, 807 differentially abundant proteins (DAPs; 536 upregulated proteins and 271 downregulated proteins in the cells cultured in the DUGL) were detected. KEGG pathway analysis of these DAPs revealed that seven pathways were enriched. These included ribosome (p < 0.0001), spliceosome (p = 0.0001), oxidative phosphorylation (p = 0.0001), protein export (p = 0.0001), thermogenesis (p = 0.0003), protein processing in the endoplasmic reticulum (p = 0.0108), and non-alcoholic fatty liver disease (p = 0.0421). Conclusion: The BBR environment inhibited the proliferation of FD-LSC-1 cells. Additionally, it induced changes in protein expression associated with the ribosome, gene spliceosome, RNA transport, and energy metabolism among others. The changes in protein expression might form the molecular basis for proliferation inhibition and enhanced survivability of cells adapting to BBR exposure in a deep underground environment. RPL26, RPS27, ZMAT2, PRPF40A, SNRPD2, SLU7, SRSF5, SRSF3, SNRPF, WFS1, STT3B, CANX, ERP29, HSPA5, COX6B1, UQCRH, and ATP6V1G1 were the core proteins associated with the BBR stress response in cells.