Brain Mitochondrial Protein Research Articles

Oral edaravone ameliorates behavioral deficits and pathologies in a valproic acid-induced rat model of autism spectrum disorder

Autism spectrum disorder (ASD) is neurodevelopmental disorder with a high incidence rate, characterized by social deficits and repetitive behaviors. There is currently no effective management available to treat the core symptoms of ASD; however, oxidative stress has been implicated in its pathogenesis. Edaravone (EDA), a free-radical scavenger, is used to treat amyotrophic lateral sclerosis (ALS) and acute ischemic stroke (AIS). Here, we hypothesized that an oral formula of EDA may have therapeutic efficacy in the treatment of core ASD symptoms. A rat model of autism was established by prenatal exposure to valproic acid (VPA), and the offsprings were orally treated with EDA at low (3 mg/kg), medium (10 mg/kg), and high (30 mg/kg) doses once daily for 28 days starting from postnatal day 25 (PND25). Oral EDA administration alleviated the core symptoms in VPA rats in a dose-dependent manner, including repetitive stereotypical behaviors and impaired social interaction. Furthermore, oral administration of EDA significantly reduced oxidative stress in a dose-dependent manner, as evidenced by a reduction in oxidative stress markers and an increase in antioxidants in the blood and brain. In addition, oral EDA significantly attenuated downstream pathologies, including synaptic and mitochondrial damage in the brain. Proteomic analysis further revealed that EDA corrected the imbalance in brain oxidative reduction and mitochondrial proteins induced by prenatal VPA administration. Overall, these findings demonstrate that oral EDA has therapeutic potential for ASD by targeting the oxidative stress pathway of disease pathogenesis and paves the way towards clinical studies.

The Relationship of Mitochondrial-derived Peptide (MOTS-c) and Brain Mitochondrial Carrier Protein 1 (BMCP1) Response in Sheep with Some Physiological Parameters

Background: Mitochondria are organelles called power plants of the cell, which are found in eukaryotic cells and are responsible for the production of energy needed by the cells through aerobic respiration. Mitochondrial dysfunction causes endocrinological, cardiovascular, metabolic and neurodegenerative diseases. The aim of this study was to examine the effects of body condition score (BCS), lactation, pregnancy, age and gender on Mitochondrial-Derived Peptide (MOTS-c) and Brain Mitochondrial Transporter Protein 1 (BMCP1) levels in Akkaraman sheep. Methods: Sheep are classified into 3 categories according to BCS (BCS less than 2, BCS=3-3.5, BCS≥4). In creating groups in terms of BCS, it was determined by the palpation method applied to the waist area. The sheep included in the study were divided into 4 groups: early lactation, early pregnancy, late pregnancy (dry period) and age (female and male sheep).1st group, ewes in the first period of pregnancy (on the 100th day of the first pregnancy) (n = 30), 2nd group, ewes in the early lactation period (n = 30), 3rd group, ewes in the dry period (the last two months of pregnancy) (n = 30) and in the 4th group, less than 2 (young) (n=30), 2-8 (adult) (n=30), 8 greater than (old) (n=30), male and female sheep (n=30) of different ages. =180) total of 270 animals. Blood samples were taken from the jugular vein of the sheep before the morning feeding. MOTSc and BMCP1 levels were determined in blood serum samples by ELISA method. Result: In the study, serum MOTS-c and BMCP1 levels in sheep during lactation and pregnancy were determined to be lowest in the VKS less than 2 group and highest in the VKS≥4 groups. Likewise, in age and gender groups, the highest level was detected in young lambs and yearlings in the VKS less than 2 group, while the highest level was detected in old sheep and rams in the VKS≥4 group. As a result, it was determined that different age, gender, pregnancy and lactation periods affected serum MOTS-c and BMCP1 levels depending on the change in BCS (P less than 0.05). It was concluded that MOTS-c and BMCP1 may be useful parameters in the evaluation of mitochondrial function, energy metabolism and metabolic profile.

Effect of Crocodile Oil (Crocodylus siamensis) on Brain Mitochondrial Protein Expression and Cognition in Male Rats

Crocodile oil (CO) is rich in polyunsaturated (PUFAs) fatty acids. Diets rich in PUFAs can maintain mitochondrial function, which is important in signal transduction and survival of neuronal cells. We investigated the effects of CO on brain mitochondrial protein expression and cognitive function in male rats. Twenty-one rats were randomly divided into three groups: (1) control, (2) treated with CO (3 mL/kg), and (3) treated with palm oil (PO; 3 mL/kg). Animals received oral gavage once-daily for seven weeks. The parameters that were measured were food intake, energy intake, body weight, serum lipid profiles, cognitive behavior, brain mitochondrial architecture, brain mitochondrial expression, and hippocampal structure. In CO and PO groups, food intake decreased significantly compared with that in the control group (p<0.05), but energy intake, body weight, and lipid profiles were not affected. Spatial learning in the PO group decreased significantly compared with that in control and CO groups (p<0.05). Crocodile oil significantly decreased the percentage of abnormal mitochondria (p<0.05) and the expression of apoptotic marker (p<0.05) compared with those in the PO treatment but also increased energy production marker (p<0.05) compared with those in the control and PO treatment. Moreover, percentage of intact hippocampal cells was not different between CO and control groups, but neuronal cells were lost in the PO group (p<0.05). This study suggest that CO could enhance the brain energy production and maintain cognitive function. CO can be an alternative dietary oil for treating brain energy disorder in the future.

Alpha pyrrolidinovalerophenone (α-PVP) administration impairs spatial learning and memory in rats through brain mitochondrial dysfunction

Novel psychoactive substances (NPS) consumption has increased in recent years, thus NPS-induced cognitive decline is a current source of concern. Alpha-pyrrolidinovalerophenone (α-PVP), as a member of NPS, is consumed throughout regions like Washington, D.C., Eastern Europe, and Central Asia. Mitochondrial dysfunction plays an essential role in NPS-induced cognitive impairment. Meanwhile, no investigations have been conducted regarding the α-PVP impact on spatial learning/memory and associated mechanisms. Consequently, our study investigated the α-PVP effect on spatial learning/memory and brain mitochondrial function. Wistar rats received different α-PVP doses (5, 10, and 20 mg/kg) intraperitoneally for 10 sequential days; 24 h after the last dose, spatial learning/memory was evaluated by the Morris Water Maze (MWM). Furthermore, brain mitochondrial protein yield and mitochondrial function variables (Mitochondrial swelling, succinate dehydrogenase (SDH) activity, lipid peroxidation, Mitochondrial Membrane Potential (MMP), Reactive oxygen species (ROS) level, brain ADP/ATP proportion, cytochrome c release, Mitochondrial Outer Membrane (MOM) damage) were examined. α-PVP higher dose (20 mg/kg) significantly impaired spatial learning/memory, mitochondrial protein yield, and brain mitochondrial function (caused reduced SDH activity, increased mitochondrial swelling, elevated ROS generation, increased lipid peroxidation, collapsed MMP, increased cytochrome c release, elevated brain ADP/ATP proportion, and MOM damage). Moreover, the lower dose of α-PVP (5 mg/kg) did not alter spatial learning/memory and brain mitochondrial function. These findings provide the first evidence regarding impaired spatial learning/memory following repeated administration of α-PVP and the possible role of brain mitochondrial dysfunction in these cognitive impairments.

Oxidative stress biomarkers and longitudinal changes in human brain imaging across the Alzheimer’s disease continuum

AbstractBackgroundOxidative stress is critical for Alzheimer’s disease (AD) pathophysiology. Brain mitochondrial function, proteins, and lipids are susceptible to oxidative damage caused by reactive oxygen species. In turn, this damage leads to key AD‐like changes in the brain, such as impaired glucose metabolism (i.e., lower fluorodeoxyglucose, or FDG‐PET) and gray matter volume atrophy in AD‐sensitive regions. It is unknown if oxidative stress biomarkers like superoxide dismutase (SOD) proteins track these changes using longitudinal brain imaging data, and what mechanisms may be at work (Figure 1).MethodUsing Alzheimer’s Disease Neuroimaging Initiative (ADNI) data, 192 aged adults (75 unimpaired, 48 MCI, 69 AD) had annual CSF and FDG data available for over 6 years. A two‐phase MRM targeted proteomics panel was used to gauge CSF SOD1 levels from serum. Standard assays in CSF determined Aβ, p‐tau‐181, and total tau. Brain glucose uptake was determined using FDG SUVR calibrated to the pons. Brain volume was examined longitudinally using FreeSurfer.ResultLongitudinally, among SOD1 quartiles (Figure 2), the lowest SOD1 group showed marked hypometabolism among older adults at baseline (R2=0.528, p<.001, “blue line”), but 6 years later instead predicted hypermetabolism (R2=0.389, p<.001). The highest SOD1 group showed no association at baseline but at 6 years later predicted hypometabolism among older adults (R2=0.151, p<.05, “dotted red line”). CSF Aβ and p‐tau‐181 fully mediated these effects (ps<.01), such that lower Aβ and higher p‐tau‐181 over time resulted in higher SOD1 predicting less glucose uptake. Similarly, higher SOD1 was not related to atrophy in AD‐sensitive regions like parahippocampus at baseline, but 5 years later was strongly related to more brain atrophy (R2=0.207,p<.001) (Figure 3), which was mediated by higher CSF total tau (p<.001).ConclusionLike previous reports, we found that SOD1 initially showed neutral or ameliorative patterns, reflecting its classical role in reducing oxidative stress. With increased Aβ or p‐tau‐181 deposition over time, however, SOD1 became a marker of the degree of oxidative damage that may have occurred in neural tissue due to Aβ or tau.

The Expression of the Low-Density Lipoprotein Receptor Modulates the Effects of Hypogonadism on Mitochondrial Activity in Different Brain Domains

Background: Testosterone deficiency (TD), brain mitochondrial uncoupling protein 2 (UCP2), and the low-density lipoprotein receptor (LDLR) are independently linked to the triggering of several behavioral disorders. Here, we investigated how TD impacts mitochondrial activity and apoptosis in different brain domains in the presence and absence of LDLR. Materials and Methods: Sham-operated or surgically castrated C57BL/6 or LDLR-deficient (Ldlr−/−) mice were fed a western-type diet for 12 weeks. Then, mitochondrial UCP2 and cytochrome c (Cytc) relative protein levels were measured as markers of uncoupling and oxidative phosphorylation, respectively, in tissue specimens from different brain domains. The ratio of the relative cytoplasmic Cytc levels over the relative mitochondrial Cytc levels (CM ratio) was used as a biochemical marker of Cytc-dependent apoptosis. Results: In cerebral hemispheres and the cerebellum area of both C57BL/6 and Ldlr−/− mice, castration resulted in increased UCP2, suggesting protection from hypogonadism-induced oxidative stress. In the broader midbrain, castration reduced UCP2 expression in C57BL/6 mice but not in Ldlr−/− mice, suggesting that LDLR deficiency protects from oxidative stress in this region. CM ratio was ≤1 after castration in these three brain domains, suggesting increased protection from Cytc-dependent apoptosis. In diencephalon, castration had no effect on UCP2 and CM ratio in C57BL/6 mice but led to increased UCP2 expression and increased CM ratio in Ldlr−/− mice, suggesting an increase in apoptosis in the diencephalon of castrated Ldlr−/− mice. Conclusions: TD in Ldlr−/− mice fed a western-type diet is associated with protection from oxidative stress but could contribute to the emergence of behavioral or systemic impairments linked to apoptosis in the diencephalon.

Differential Abundance of Brain Mitochondrial Proteins in Yak and Cattle: A Proteomics-Based Study.

The plateau adaptability and stress resistance of yaks are widely known based on their capacity to survive under severe habitat conditions. However, a few studies on brain mitochondria have characterized these adaptations at the protein level. We identified and quantified the brain mitochondrial proteins using isobaric tags for relative and absolute quantification (iTRAQ) and Proteomics. Western blotting was used to verify changes in the expression of target proteins. A total of 57 differentially abundant proteins (DAPs) were identified in the yak brain tissue. Gene Ontology (GO) analysis showed molecular functions of these DAPs including downregulated oxidoreductase activity but upregulated coenzyme binding. Significantly enriched biological processes were oxidation–reduction process (downregulated) and small molecule metabolic processes (upregulated). STRING protein interaction analysis indicated a complex interaction between dehydrogenase, transaminase, and ATP synthetase families. Reactome pathway analysis highlighted that the majority of DAPs participated in aerobic metabolic pathways such as metabolism, citric acid cycle, and respiratory electron transport. Immunoblotting confirmed that changes in FKBP4 and ATPAF2 expression were consistent with the results of mass spectrometry. We performed a high-throughput screening to identify DAPs in brain mitochondria between yak and cattle, which could explain the plateau adaptability of yaks.

N-Propargylglycine: a unique suicide inhibitor of proline dehydrogenase with anticancer activity and brain-enhancing mitohormesis properties

Proline dehydrogenase (PRODH) is a mitochondrial inner membrane flavoprotein critical for cancer cell survival under stress conditions and newly recognized as a potential target for cancer drug development. Reversible (competitive) and irreversible (suicide) inhibitors of PRODH have been shown in vivo to inhibit cancer cell growth with excellent host tolerance. Surprisingly, the PRODH suicide inhibitor N-propargylglycine (N-PPG) also induces rapid decay of PRODH with concordant upregulation of mitochondrial chaperones (HSP-60, GRP-75) and the inner membrane protease YME1L1, signifying activation of the mitochondrial unfolded protein response (UPRmt) independent of anticancer activity. The present study was undertaken to address two aims: (i) use PRODH overexpressing human cancer cells (ZR-75-1) to confirm the UPRmt inducing properties of N-PPG relative to another equipotent irreversible PRODH inhibitor, thiazolidine-2-carboxylate (T2C); and (ii) employ biochemical and transcriptomic approaches to determine if orally administered N-PPG can penetrate the blood–brain barrier, essential for its future use as a brain cancer therapeutic, and also potentially protect normal brain tissue by inducing mitohormesis. Oral daily treatments of N-PPG produced a dose-dependent decline in brain mitochondrial PRODH protein without detectable impairment in mouse health; furthermore, mice repeatedly dosed with 50 mg/kg N-PPG showed increased brain expression of the mitohormesis associated protease, YME1L1. Whole brain transcriptome (RNAseq) analyses of these mice revealed significant gene set enrichment in N-PPG stimulated neural processes (FDR p < 0.05). Given this in vivo evidence of brain bioavailability and neural mitohormesis induction, N-PPG appears to be unique among anticancer agents and should be evaluated for repurposing as a pharmaceutical capable of mitigating the proteotoxic mechanisms driving neurodegenerative disorders.

Changes in the mitochondrial subproteome of mouse brain Rpn13-binding proteins induced by the neurotoxin MPTP and the neuroprotector isatin

Mitochondrial dysfunction and ubiquitin-proteasome system (UPS) failure contribute significantly to the development of Parkinson's disease (PD). The proteasome subunit Rpn13 located on the regulatory (19S) subparticle play an important role in the delivery of proteins, subjected to degradation, to the proteolytic (20S) part of proteasome. We have previously found several brain mitochondrial proteins specifically bound to Rpn13 (Buneeva et al. (2020) Biochemistry (Moscow), Supplement Series B: Biomedical Chemistry, 14, 297-305). In this study we have investigated the effect of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and the neuroprotector isatin on the mitochondrial subproteome of Rpn13-binding proteins of the mouse brain. Administration of MPTP (30 mg/kg) to animals caused movement disorders typical of PD, while pretreatment with isatin (100 mg/kg, 30 min before MPTP) reduced their severity. At the same time, the injection of MPTP, isatin, or their combination (isatin + MPTP) had a significant impact on the total number and the composition of Rpn13-binding proteins. The injection of MPTP decreased the total number of Rpn13-binding proteins in comparison with control, and the injection of isatin prior to MPTP or without MPTP caused an essential increase in the number of Rpn13-binding proteins, mainly of the functional group of proteins participating in the protein metabolism regulation, gene expression, and differentiation. Selected biosensor validation confirmed the interaction of Rpn13 subunit of proteasome with some proteins (glyceraldehyde-3-phosphate dehydrogenase, pyruvate kinase, histones H2A and H2B) revealed while proteomic profiling. The results obtained testify that under the conditions of experimental MPTP-induced parkinsonism the neuroprotective effect of isatin may be aimed at the interaction of mitochondria with the components of UPS.

Ubiquitin Subproteome of Brain Mitochondria and Its Changes Induced by Experimental Parkinsonism and Action of Neuroprotectors.

The review summarizes the data of our research and published studies on the ubiquitination of brain mitochondrial proteins and its changes during the development of experimental parkinsonism and administration of the neuroprotector isatin (indole-2,3-dione) with special attention to the mitochondrial ubiquitin-conjugating system and location of ubiquitinated proteins in these organelles. Incubation of brain mitochondrial fraction with biotinylated ubiquitin in vitro resulted in the incorporation of biotinylated ubiquitin in both mitochondrial and mitochondria-associated proteins. According to the interactome analysis, the identified non-ubiquitinated proteins are able to form tight complexes with ubiquitinated proteins or their partners and components of mitochondrial membranes, in which interactions of ubiquitin chains with the ubiquitin-binding protein domains play an important role. The studies of endogenous ubiquitination in the total brain mitochondrial fraction of C57Bl mice performed in different laboratories have shown that mitochondrial proteins represent about 30% of all ubiquitinated proteins. However, comparison of brain subproteomes of mitochondrial ubiquitinated proteins reported in the literature revealed significant differences both in their composition and involvement of identified ubiquitinated proteins in biological processes listed in the Gene Ontology database. The development of experimental parkinsonism in C57Bl mice induced by a single-dose administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) resulted in a decrease in the total number of mitochondrial ubiquitinated proteins and increase in the number of oxidized mitochondrial proteins containing the ubiquitin signature (K-ε-GG). Comparison of ubiquitinated proteins associated with the mouse brain mitochondrial fraction and mouse brain mitochondrial proteins bound to the proteasome ubiquitin receptor (Rpn10 subunit) did not reveal any common proteins. This suggests that ubiquitination of brain mitochondrial proteins is not directly related to their degradation in the proteasomes. Proteomic profiling of brain isatin-binding proteins identified enzymes involved in the ubiquitin-conjugating system functioning. Mapping of the identified isatin-binding proteins to known metabolic pathways indicates their participation in the parkin (E3 ubiquitin ligase)-associated pathway (CH000000947). The functional links involving brain mitochondrial ubiquitinated proteins were found only in the group of animals with the MPTP-induced parkinsonism, but not in animals treated with MPTP/isatin or isatin only. This suggests that the neuroprotective effect of isatin may be associated with the impaired functional relationships of proteins targeted to subsequent degradation.

The human uncoupling proteins 5 and 6 (UCP5/SLC25A14 and UCP6/SLC25A30) transport sulfur oxyanions, phosphate and dicarboxylates

The human genome encodes 53 members of the solute carrier family 25 (SLC25), also called the mitochondrial carrier family. In this work, two members of this family, UCP5 (BMCP1, brain mitochondrial carrier protein 1 encoded by SLC25A14) and UCP6 (KMCP1, kidney mitochondrial carrier protein 1 encoded by SLC25A30) have been thoroughly characterized biochemically. They were overexpressed in bacteria, purified and reconstituted in phospholipid vesicles. Their transport properties and kinetic parameters demonstrate that UCP5 and UCP6 transport inorganic anions (sulfate, sulfite, thiosulfate and phosphate) and, to a lesser extent, a variety of dicarboxylates (e.g. malonate, malate and citramalate) and, even more so, aspartate and (only UCP5) glutamate and tricarboxylates. Both carriers catalyzed a fast counter-exchange transport and a very low uniport of substrates. Transport was saturable and inhibited by mercurials and other mitochondrial carrier inhibitors at various degrees. The transport affinities of UCP5 and UCP6 were higher for sulfate and thiosulfate than for any other substrate, whereas the specific activity of UCP5 was much higher than that of UCP6. It is proposed that a main physiological role of UCP5 and UCP6 is to catalyze the export of sulfite and thiosulfate (the H2S degradation products) from the mitochondria, thereby modulating the level of the important signal molecule H2S.

SIRT3 deficiency-induced mitochondrial dysfunction and inflammasome formation in the brain

SIRT3, the primary mitochondrial deacetylase, plays a significant role in enhancing the function of mitochondrial proteins. Downregulation of SIRT3 is a key component of metabolic syndrome, a precondition for obesity, diabetes and cardiovascular diseases. In this study, we examined the effects of brain mitochondrial protein hyperacetylation in western diet-fed Sirt3−/− mice, a model for metabolic syndrome. Brain mitochondrial proteins were hyperacetylated, following western diet feeding and Sirt3 deletion. To identity these hyperacetylated proteins, we performed a comprehensive acetylome analysis by label-free tandem mass spectrometry. Gene ontology pathway analysis revealed Sirt3 deletion-mediated downregulation of enzymes in several metabolic pathways, including fatty acid oxidation and tricarboxylic acid cycle. Mitochondrial respiration was impaired at multiple states, along with lower levels of mitochondrial fission proteins Mfn1 and Mfn2. Cleavage of procaspase-1 suggested inflammasome formation. Assembly of inflammasomes with caspase-1 and NLRP3 was detected as shown by proximity ligation assay. Markers of neuroinflammation including microgliosis and elevated brain IL-1β expression were also observed. Importantly, these findings were further exacerbated in Sirt3−/− mice when fed a calorie-rich western diet. The observations of this study suggest that SIRT3 deficiency-induced brain mitochondrial dysfunction and neuroinflammation in metabolic syndrome may play a role in late-life cognitive decline.

The Effect of Neurotoxin MPTP and Neuroprotector Isatin on the Profile of Ubiquitinated Brain Mitochondrial Proteins.

Mitochondria are a crucial target for the actions of neurotoxins, causing symptoms of Parkinson’s disease in various experimental animal models, and also neuroprotectors. There is evidence that mitochondrial dysfunction induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) influences functioning of the ubiquitin-proteasomal system (UPS) responsible for selective proteolytic degradation of proteins from various intracellular compartments (including mitochondria) and neuroprotective effects of certain anti-Parkisonian agents (monoamine oxidase inhibitors) may be associated with their effects on the UPS. In this study, we have investigated the effect of the neurotoxin MPTP and neuroprotector isatin, and their combination on the profile of ubiquitinated brain mitochondrial proteins. The development of movement disorders induced by MPTP administration caused dramatic changes in the profile of ubiquitinated proteins associated with mitochondria. Pretreatment with the neuroprotector isatin decreased manifestations of MPTP-induced Parkinsonism, and had a significant impact on the profile of ubiquitinated mitochondrial proteins (including oxidative modified proteins). Administration of isatin alone to intact mice also influenced the profile of ubiquitinated mitochondrial proteins, and increased the proportion of oxidized proteins carrying the ubiquitination signature. These alterations in the ubiquitination of mitochondrial proteins observed within 2 h after administration of MPTP and isatin obviously reflect immediate short-term biological responses to these treatments.

Evaluation of the effectiveness of chronic antidepressant drug treatments in the hippocampal mitochondria – A proteomic study in an animal model of depression

Several lines of evidence indicate that adverse experience in early life may be a triggering factor for disturbances in the brain mitochondrial proteins and lead to the development of depression in adulthood. On the other hand, little is known about the impact of chronic administration of various antidepressant drugs on the brain mitochondria, as a target for the pharmacotherapy of depression.The purpose of our study was to compare the impact of chronic treatment with two antidepressant drugs with different mechanisms of action, a tricyclic antidepressant (TCA), imipramine, and an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class, fluoxetine, on the mitochondria-enriched subproteome profile in the hippocampus of 3-month-old male rats following a prenatal stress procedure (an animal model of depression).We clearly confirmed that chronic imipramine and fluoxetine administration not only normalized depression-like disturbances evoked by the prenatal stress procedure but also modulated the mitochondria-enriched subproteome profile in the hippocampus of adult offspring rats. In line with this, two-dimensional electrophoresis coupled with mass spectrometry showed a statistically significant down-regulation of 14-3-3 and cytochrome bc1 proteins and an up-regulation of COP9 signalosome expression after chronic imipramine treatment in the hippocampus of prenatally stressed offspring. Fluoxetine administration strongly up-regulated the expression of cathepsin D, one of the key proteins involved in the prevention of the development of neurodegenerative processes. Furthermore, this antidepressant treatment enhanced expression of proteins engaged in the improvement of learning and memory processes (STMN1, Dnm-1) as well as in mitochondrial biogenesis and defense against oxidative stress (DJ-1).These findings provide new evidence that chronic administration of antidepressants exerts a varied impact on the mitochondria-enriched subproteome in the hippocampus of adult rats following a prenatal stress procedure. In particular, the effect of fluoxetine requires additional experiments to elucidate the possible beneficial biological consequences underlying the effects mediated by this antidepressant.

Brain Mitochondrial Subproteome of Rpn10-Binding Proteins and Its Changes Induced by the Neurotoxin MPTP and the Neuroprotector Isatin.

Mitochondria play an important role in molecular mechanisms of neuroplasticity, adaptive changes of the brain that occur in the structure and function of its cells in response to altered physiological conditions or development of pathological disorders. Mitochondria are a crucial target for actions of neurotoxins, causing symptoms of Parkinson's disease in various experimental animal models, and also neuroprotectors. Good evidence exists in the literature that mitochondrial dysfunction induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) influences functioning of the ubiquitin-proteasomal system (UPS) responsible for selective proteolytic degradation of proteins from various intracellular compartments (including mitochondria), and neuroprotective effects of certain antiparkinsonian agents (monoamine oxidase inhibitors) may be associated with their effects on UPS. The 19S proteasomal Rpn10 subunit is considered as a ubiquitin receptor responsible for delivery of ubiquitinated proteins to the proteasome proteolytic machinery. In this study, we investigated proteomic profiles of mouse brain mitochondrial Rpn10-binding proteins, brain monoamine oxidase B (MAO B) activity, and their changes induced by a single-dose administration of the neurotoxin MPTP and the neuroprotector isatin. Administration of isatin to mice prevented MPTP-induced inactivation of MAO B and influenced the profile of brain mitochondrial Rpn10-binding proteins, in which two pools of proteins were clearly recognized. The constitutive pool was insensitive to neurotoxic/neuroprotective treatments, while the variable pool was specifically influenced by MPTP and the neuroprotector isatin. Taking into consideration that the neuroprotective dose of isatin used in this study can result in brain isatin concentrations that are proapoptotic for cells in vitro, the altered repertoire of mitochondrial Rpn10-binding proteins may thus represent a part of a switch mechanism from targeted elimination of individual (damaged) proteins to more efficient ("global") elimination of damaged organelles and whole damaged cells.

The effect of chronic tianeptine administration on the brain mitochondria: direct links with an animal model of depression.

A growing body of evidence has focused on the impact of mitochondrial disturbances in the development of depression, but little data exist regarding the effects of chronic administration of antidepressant drugs on the brain’s mitochondrial protein profile. The aim of this study was to investigate the impact of chronic treatment with an atypical antidepressant drug—tianeptine—on the mitochondria-enriched subproteome profile in the hippocampus and the frontal cortex of 3-month-old male rats following a prenatal stress procedure. Rats that were exposed to a prenatal stress procedure displayed depressive- and anxiety-like disturbances based on the elevated plus-maze and Porsolt tests. Moreover, two-dimensional electrophoresis coupled with mass spectrometry showed structure-dependent mitoproteome changes in brains of prenatally stressed rats after chronic tianeptine administration. A component of 2-oxoglutarate and succinate flavoprotein subunit dehydrogenases, isocitrate subunit alpha, was upregulated in the hippocampus. In the frontal cortex, there was a striking increase in the expression of glutamate dehydrogenase and cytochrome bc1 complex subunit 2. These findings suggest that mitochondria are underappreciated targets for therapeutic interventions, and mitochondrial function may be crucial for the effective treatment of stress-related diseases.

Interaction of paroxetine with mitochondrial proteins mediates neuroprotection.

There are severe neurological complications that arise from HIV infection, ranging from peripheral sensory neuropathy to cognitive decline and dementia for which no specific treatments are available. The HIV proteins secreted from infected macrophages, gp120 and Tat, are neurotoxic. The goal of this study was to screen, identify and develop neuroprotective compounds relevant to HIV-associated neurocognitive disorders (HAND). We screened more than 2000 compounds that included FDA approved drugs for protective efficacy against oxidative stress-mediated neurodegeneration and identified selective serotonin reuptake inhibitors (SSRIs) as potential neuroprotectants. Numerous SSRIs were then extensively evaluated as protectants against neurotoxicity as measured by changes in neuronal cell death, mitochondrial potential, and axodendritic degeneration elicited by HIV Tat and gp120 and other mitochondrial toxins. While many SSRIs demonstrated neuroprotective actions, paroxetine was potently neuroprotective (100 nM potency) against these toxins in vitro and in vivo following systemic administration in a gp120 neurotoxicity model. Interestingly, the inhibition of serotonin reuptake by paroxetine was not required for neuroprotection, since depletion of the serotonin transporter had no effect on its neuroprotective properties. We determined that paroxetine interacts selectively and preferentially with brain mitochondrial proteins and blocks calcium-dependent swelling but had less effect on liver mitochondria. Additionally, paroxetine induced proliferation of neural progenitor cells in vitro and in vivo in gp120 transgenic animals. Therefore, SSRIs such as paroxetine may provide a novel adjunctive neuroprotective and neuroregenerative therapy to treat HIV-infected individuals.

Epsilon PKC Increases Brain Mitochondrial SIRT1 Protein Levels via Heat Shock Protein 90 following Ischemic Preconditioning in Rats

Ischemic preconditioning is a neuroprotective mechanism whereby a sublethal ischemic exposure is protective against a subsequent lethal ischemic attack. We previously demonstrated that SIRT1, a nuclear localized stress-activated deacetylase, is vital for ischemic preconditioning neuroprotection. However, a recent study demonstrated that SIRT1 can also localize to the mitochondria. Mitochondrial localized SIRT1 may allow for a direct protection of mitochondria following ischemic preconditioning. The objective of this study was to determine whether ischemic preconditioning increases brain mitochondrial SIRT1 protein levels and to determine the role of PKCɛ and HSP90 in targeting SIRT1 to the mitochondria. Here we report that preconditioning rats, with 2 min of global cerebral ischemia, induces a delayed increase in non-synaptic mitochondrial SIRT1 protein levels which was not observed in synaptic mitochondria. This increase in mitochondrial SIRT1 protein was found to occur only in neuronal cells and was mediated by PKCε activation. Inhibition of HSP90, a protein chaperone involved in mitochondrial protein import, prevented preconditioning induced increases in mitochondrial SIRT1 and PKCε protein. Our work provides new insights into a possible direct role of SIRT1 in modulating mitochondrial function under both normal and stress conditions, and to a possible role of mitochondrial SIRT1 in activating preconditioning induced ischemic tolerance.

Lack of p53 Affects the Expression of Several Brain Mitochondrial Proteins: Insights from Proteomics into Important Pathways Regulated by p53

The tumor suppressor protein p53 has been described “as the guardian of the genome” for its crucial role in regulating the transcription of numerous genes responsible for cells cycle arrest, senescence, or apoptosis in response to various stress signals. Although p53 promotes longevity by decreasing the risk of cancer through activation of apoptosis or cellular senescence, several findings suggest that an increase of its activity may have deleterious effects leading to selected aspects of the aging phenotype and neurodegenerative diseases. There is the link between p53 and oxidative stress, the latter a crucial factor that contributes to neurodegenerative processes like Alzheimer disease (AD). In the present study, using a proteomics approach, we analyzed the impact of lack of p53 on the expression of several brain mitochondrial proteins involved in different pathways, and how lack of p53 may present a target to restore neuronal impairments. Our investigation on isolated brain mitochondria from p53(−/−) mice also provides a better understanding of the p53-mitochondria relationship and its involvement in the development of many diseases.

Mitochondrial proteome analysis reveals depression of the Ndufs3 subunit and activity of complex I in diabetic rat brain

Type-1 diabetes resulting from defective insulin secretion and consequent hyperglycemia, is associated with "diabetic encephalopathy." This is characterized by brain neurophysiological and structural changes resulting in impairment of cognitive function. The present proteomic analysis of brain mitochondrial proteins from streptozotocin-induced type-1 diabetic rats, shows a large decrement of the Ndufs3 protein subunit of complex I, decreased level of the mRNA and impaired catalytic activity of the complex in the diabetic rats as compared to controls. The severe depression of the expression and enzymatic activity of complex I can represent a critical contributing factor to the onset of the diabetic encephalopathy in type-1 diabetes.