Mitochondria and degenerative disorders

Alzheimer's diseases in America, Europe, and Asian regions: a global genetic variation

Background

Alzheimer's disease (AD) is one of the multifaceted neurodegenerative diseases influenced by many genetic and epigenetic factors. Genetic factors are merely not responsible for developing AD in the whole population. The studies of genetic variants can provide significant insights into the molecular basis of Alzheimer's disease. Our research aimed to show how genetic variants interact with environmental influences in different parts of the world.

Methodology

We searched PubMed and Google Scholar for articles exploring the relationship between genetic variations and global regions such as America, Europe, and Asia. We aimed to identify common genetic variations susceptible to AD and have no significant heterogeneity. To achieve this, we analyzed 35 single-nucleotide polymorphisms (SNPs) from 17 genes (ABCA7, APOE, BIN1, CD2AP, CD33, CLU, CR1, EPHA1, TOMM40, MS4A6A, ARID5B, SORL1, APOC1, MTHFD1L, BDNF, TFAM, and PICALM) from different regions based on previous genomic studies of AD. It has been reported that rs3865444, CD33, is the most common polymorphism in the American and European populations. From TOMM40 and APOE rs2075650, rs429358, and rs6656401, CR1 is the common investigational polymorphism in the Asian population.

Conclusion

The results of all the research conducted on AD have consistently shown a correlation between genetic variations and the incidence of AD in the populations of each region. This review is expected to be of immense value in future genetic research and precision medicine on AD, as it provides a comprehensive understanding of the genetic factors contributing to the development of this debilitating disease.

L-Carnitine in the Treatment of Psychiatric and Neurological Manifestations: A Systematic Review

OBJECTIVE

L-carnitine (LC), a vital nutritional supplement, plays a crucial role in myocardial health and exhibits significant cardioprotective effects. LC, being the principal constituent of clinical-grade supplements, finds extensive application in the recovery and treatment of diverse cardiovascular and cerebrovascular disorders. However, controversies persist regarding the utilization of LC in nervous system diseases, with varying effects observed across numerous mental and neurological disorders. This article primarily aims to gather and analyze database information to comprehensively summarize the therapeutic potential of LC in patients suffering from nervous system diseases while providing valuable references for further research.

METHODS

A comprehensive search was conducted in PubMed, Web Of Science, Embase, Ovid Medline, Cochrane Library and Clinicaltrials.gov databases. The literature pertaining to the impact of LC supplementation on neurological or psychiatric disorders in patients was reviewed up until November 2023. No language or temporal restrictions were imposed on the search.

RESULTS

A total of 1479 articles were retrieved, and after the removal of duplicates through both automated and manual exclusion processes, 962 articles remained. Subsequently, a meticulous re-screening led to the identification of 60 relevant articles. Among these, there were 12 publications focusing on hepatic encephalopathy (HE), while neurodegenerative diseases (NDs) and peripheral nervous system diseases (PNSDs) were represented by 9 and 6 articles, respectively. Additionally, stroke was addressed in five publications, whereas Raynaud's syndrome (RS) and cognitive disorder (CD) each had three dedicated studies. Furthermore, migraine, depression, and amyotrophic lateral sclerosis (ALS) each accounted for two publications. Lastly, one article was found for other symptoms under investigation.

CONCLUSION

In summary, LC has demonstrated favorable therapeutic effects in the management of HE, Alzheimer's disease (AD), carpal tunnel syndrome (CTS), CD, migraine, neurofibromatosis (NF), PNSDs, RS, and stroke. However, its efficacy appears to be relatively limited in conditions such as ALS, ataxia, attention deficit hyperactivity disorder (ADHD), depression, chronic fatigue syndrome (CFS), Down syndrome (DS), and sciatica.

Transcriptomic meta-analysis reveals ERRα-mediated oxidative phosphorylation is downregulated in Fuchs' endothelial corneal dystrophy

BACKGROUND

Late-onset Fuchs' endothelial corneal dystrophy (FECD) is a degenerative disease of cornea and the leading indication for corneal transplantation. Genetically, FECD patients can be categorized as with (RE+) or without (RE-) the CTG trinucleotide repeat expansion in the transcription factor 4 gene. The molecular mechanisms underlying FECD remain unclear, though there are plausible pathogenic models proposed for RE+ FECD.

METHOD

In this study, we performed a meta-analysis on RNA sequencing datasets of FECD corneal endothelium including 3 RE+ datasets and 2 RE- datasets, aiming to compare the transcriptomic profiles of RE+ and RE- FECD. Gene differential expression analysis, co-expression networks analysis, and pathway analysis were conducted.

RESULTS

There was a striking similarity between RE+ and RE- transcriptomes. There were 1,184 genes significantly upregulated and 1,018 genes significantly downregulated in both RE+ and RE- cases. Pathway analysis identified multiple biological processes significantly enriched in both-mitochondrial functions, energy-related processes, ER-nucleus signaling pathway, demethylation, and RNA splicing were negatively enriched, whereas small GTPase mediated signaling, actin-filament processes, extracellular matrix organization, stem cell differentiation, and neutrophil mediated immunity were positively enriched. The translational initiation process was downregulated in the RE+ transcriptomes. Gene co-expression analysis identified modules with relatively distinct biological processes enriched including downregulation of mitochondrial respiratory chain complex assembly. The majority of oxidative phosphorylation (OXPHOS) subunit genes, as well as their upstream regulator gene estrogen-related receptor alpha (ESRRA), encoding ERRα, were downregulated in both RE+ and RE- cases, and the expression level of ESRRA was correlated with that of OXPHOS subunit genes.

CONCLUSION

Meta-analysis increased the power of detecting differentially expressed genes. Integrating differential expression analysis with co-expression analysis helped understand the underlying molecular mechanisms. FECD RE+ and RE- transcriptomic profiles are much alike with the hallmark of downregulation of genes in pathways related to ERRα-mediated OXPHOS.

Mitochondrial Bioenergy in Neurodegenerative Disease: Huntington and Parkinson

Strong evidence suggests a correlation between degeneration and mitochondrial deficiency. Typical cases of degeneration can be observed in physiological phenomena (i.e., ageing) as well as in neurological neurodegenerative diseases and cancer. All these pathologies have the dyshomeostasis of mitochondrial bioenergy as a common denominator. Neurodegenerative diseases show bioenergetic imbalances in their pathogenesis or progression. Huntington's chorea and Parkinson's disease are both neurodegenerative diseases, but while Huntington's disease is genetic and progressive with early manifestation and severe penetrance, Parkinson's disease is a pathology with multifactorial aspects. Indeed, there are different types of Parkinson/Parkinsonism. Many forms are early-onset diseases linked to gene mutations, while others could be idiopathic, appear in young adults, or be post-injury senescence conditions. Although Huntington's is defined as a hyperkinetic disorder, Parkinson's is a hypokinetic disorder. However, they both share a lot of similarities, such as neuronal excitability, the loss of striatal function, psychiatric comorbidity, etc. In this review, we will describe the start and development of both diseases in relation to mitochondrial dysfunction. These dysfunctions act on energy metabolism and reduce the vitality of neurons in many different brain areas.

Meta-analysis of brain samples of individuals with schizophrenia detects down-regulation of multiple ATP synthase encoding genes in both females and males

Schizophrenia is a chronic and debilitating mental disorder, with unknown pathophysiology. Converging lines of evidence suggest that mitochondrial functioning may be compromised in schizophrenia. Postmortem brain samples of individuals with schizophrenia showed dysregulated expression levels of genes encoding enzyme complexes comprising the mitochondrial electron transport chain (ETC), including ATP synthase, the fifth ETC complex. However, there are inconsistencies regarding the direction of change, i.e., up- or down-regulation, and differences between female and male patients were hardly examined. We have performed a systematic meta-analysis of the expression of 16 ATP synthase encoding genes in postmortem brain samples of individuals with schizophrenia vs. healthy controls of three regions: Brodmann Area 10 (BA10), BA22/Superior Temporal Gyrus (STG) and the cerebellum. Eight independent datasets were integrated (overall 294brain samples, 145 of individuals with schizophrenia and 149 controls). The meta-analysis was applied to all individuals with schizophrenia vs. the controls, and also to female and male patients vs. age-matched controls, separately. A significant down-regulation of two ATP synthase encoding genes was detected in schizophrenia, ATP5A1 and ATP5H, and a trend towards down-regulation of five further ATP synthase genes. The down-regulation tendency was shown for both females and males with schizophrenia. Our findings support the hypothesis that schizophrenia is associated with reduced ATP synthesis via the oxidative phosphorylation system, which is caused by reduced cellular demand of ATP. Abnormal cellular energy metabolism can lead to alterations in neural function and brain circuitry, and thereby to the cognitive and behavioral aberrations characteristic of schizophrenia.

Role of ketone bodies in diabetes-induced dementia: sirtuins, insulin resistance, synaptic plasticity, mitochondrial dysfunction, and neurotransmitter

Patients with type 2 diabetes can have several neuropathologies, such as memory deficits. Recent studies have focused on the association between metabolic imbalance and neuropathological problems, and the associated molecular pathology. Diabetes triggers neuroinflammation, impaired synaptic plasticity, mitochondrial dysfunction, and insulin resistance in the brain. Glucose is a main energy substrate for neurons, but under certain conditions, such as fasting and starvation, ketone bodies can be used as an energy fuel for these cells. Recent evidence has shed new light on the role of ketone bodies in regulating several anti-inflammation cellular pathways and improving glucose metabolism, insulin action, and synaptic plasticity, thereby being neuroprotective. However, very high amount of ketone bodies can be toxic for the brain, such as in ketoacidosis, a dangerous complication that may occur in type 1 diabetes mellitus or alcoholism. Recent findings regarding the relationship between ketone bodies and neuropathogenesis in dementia are reviewed in this article. They suggest that the adequately low amount of ketone bodies can be a potential energy source for the treatment of diabetes-induced dementia neuropathology, considering the multifaceted effects of the ketone bodies in the central nervous system. This review can provide useful information for establishing the therapeutic guidelines of a ketogenic diet for diabetes-induced dementia.

A first description of ataxia with vitamin E deficiency associated with MT-TG gene mutation

Ataxia with isolated vitamin E deficiency (AVED) is a rare autosomal recessive cerebellar ataxia disorder that is caused by a mutation in the alpha-tocopherol transfer protein gene TTPA, leading to a lower level of serum vitamin E. Although it is almost clinically similar to Friedreich's ataxia, its devastating neurological features can be prevented with appropriate treatment. In this study, we present a patient who was initially diagnosed with Friedreich's ataxia, but was later found to have AVED. Frataxin gene screening revealed the absence of GAA expansion in homozygous or heterozygous state. However, TTPAgene sequencing showed the presence of the c.744delA mutation, leading to a premature stop codon (p.E249fx). In addition, the result of mutational analysis of MT-DNA genes revealed the presence of several variants, including the m.10044A>G mutation in MT-TG gene. Here, we report for the first time the coexistence of both mitochondrial and nuclear genes mutations in AVED.

The interplay among oxidative stress, brain insulin resistance and AMPK dysfunction contribute to neurodegeneration in type 2 diabetes and Alzheimer disease

Alzheimer's disease (AD) is the most common form of dementia in the elderly followed by vascular dementia. In addition to clinically diagnosed dementia, cognitive dysfunction has been reported in diabetic patients. Recent studies are now beginning to recognize type 2 diabetes mellitus (T2DM), characterized by chronic hyperglycemia and insulin resistance, as a risk factor for AD and other cognitive disorders. While studies on insulin action have remained traditionally in the domain of peripheral tissues, the detrimental effects of insulin resistance in the central nervous system on cognitive dysfunction are increasingly being reported in recent clinical and preclinical studies. Brain functions require continuous supply of glucose and oxygen and a tight regulation of metabolic processes. Loss of this metabolic regulation has been proposed to be a contributor to memory dysfunction associated with neurodegeneration. Within the above scenario, this review will focus on the interplay among oxidative stress (OS), insulin resistance and AMPK dysfunctions in the brain by highlighting how these neurotoxic events contribute to neurodegeneration. We provide an overview on the detrimental effects of OS on proteins regulating insulin signaling and how these alterations impact cell metabolic dysfunctions through AMPK dysregulation. Such processes, we assert, are critically involved in the molecular pathways that underlie AD.

Diabetes and Alzheimer's Disease: Might Mitochondrial Dysfunction Help Deciphering the Common Path?

A growing number of clinical and epidemiological studies support the hypothesis of a tight correlation between type 2 diabetes mellitus (T2DM) and the development risk of Alzheimer's disease (AD). Indeed, the proposed definition of Alzheimer's disease as type 3 diabetes (T3D) underlines the key role played by deranged insulin signaling to accumulation of aggregated amyloid beta (Aβ) peptides in the senile plaques of the brain. Metabolic disturbances such as hyperglycemia, peripheral hyperinsulinemia, dysregulated lipid metabolism, and chronic inflammation associated with T2DM are responsible for an inefficient transport of insulin to the brain, producing a neuronal insulin resistance that triggers an enhanced production and deposition of Aβ and concomitantly contributes to impairment in the micro-tubule-associated protein Tau, leading to neural degeneration and cognitive decline. Furthermore, the reduced antioxidant capacity observed in T2DM patients, together with the impairment of cerebral glucose metabolism and the decreased performance of mitochondrial activity, suggests the existence of a relationship between oxidative damage, mitochondrial impairment, and cognitive dysfunction that could further reinforce the common pathophysiology of T2DM and AD. In this review, we discuss the molecular mechanisms by which insulin-signaling dysregulation in T2DM can contribute to the pathogenesis and progression of AD, deepening the analysis of complex mechanisms involved in reactive oxygen species (ROS) production under oxidative stress and their possible influence in AD and T2DM. In addition, the role of current therapies as tools for prevention or treatment of damage induced by oxidative stress in T2DM and AD will be debated.

Alzheimer’s disease and type 2 diabetes mellitus: Pathophysiologic and pharmacotherapeutics links

At present, Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2DM) are two highly prevalent disorders worldwide, especially among elderly individuals. T2DM appears to be associated with cognitive dysfunction, with a higher risk of developing neurocognitive disorders, including AD. These diseases have been observed to share various pathophysiological mechanisms, including alterations in insulin signaling, defects in glucose transporters (GLUTs), and mitochondrial dysfunctions in the brain. Therefore, the aim of this review is to summarize the current knowledge regarding the molecular mechanisms implicated in the association of these pathologies as well as recent therapeutic alternatives. In this context, the hyperphosphorylation of tau and the formation of neurofibrillary tangles have been associated with the dysfunction of the phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways in the nervous tissues as well as the decrease in the expression of GLUT-1 and GLUT-3 in the different areas of the brain, increase in reactive oxygen species, and production of mitochondrial alterations that occur in T2DM. These findings have contributed to the implementation of overlapping pharmacological interventions based on the use of insulin and antidiabetic drugs, or, more recently, azeliragon, amylin, among others, which have shown possible beneficial effects in diabetic patients diagnosed with AD.

THE SEARCH FOR NEUROPROTECTIVE COMPOUNDS AMONG NEW ETHYLTHIADIAZOLE DERIVATIVES

The aim of the study is to search compounds with neuroprotective properties among new ethylthiadiazole derivatives in simulated traumatic brain injury.

Materials and methods. The experiment was carried out on 78 white male rats 270±20 g line “Wistar” 5–6 months of age and 120 outbred sexually mature mice weighing 20±2 grams. The article describes the search for compounds with neuroprotective properties among new ethylthiadiazole derivatives under the codes LKHT 4–15, LKHT 10–18, LKHT 11–18, and LKHT 12–18 in experimental traumatic brain injury in rats. Acute toxicity of the compounds was studied. Pharmacological screening was performed using behavioral and neurological research methods. The McGraw stroke score scale modified by I.V. Gannushkina and the mNSS psychometric scale were used in the study. The open field and Rota-rod tests were used to assess the behavioral status of the animals.

Results. The compound-LKHT 12–18 at a dose of 50 mg/kg was detected as a leader. In pharmacological correction of pathology, this compound had the lowest percentage of fatality among the studied compounds (8%), the severity of neurological deficit was significantly reduced, the lowest scores and a higher level of motor activity of the limbs were registered. The number of rearing in the group of animals receiving the compound LKHT 12–18 at the dose of 50 mg/kg increased by 1.5 times, statistically significant (p<0.05) in comparison with the control group. Based on the results of the “Rota-rod” test, the total time of holding animals on the rod for 3 attempts was statistically significantly different in the groups administered with LKHT 12–18 derivatives (1.5 times longer) at the dose of 50 mg/kg compared with the control (p<0.05).

Conclusion. Based on the results obtained in this study, it is planned to study in more detail the compound LKHT 12–18 at the dose of 50 mg/kg.

Measurement of Mitochondrial Respiration in Platelets

Platelet mitochondria can be used in the study of mitochondrial dysfunction in various complex diseases and can help in finding biological markers for diagnosing the disease, monitoring its course and the effects of treatment. The aim of this chapter was to describe in detail the method of measuring mitochondrial respiration in platelets using high-resolution respirometry. The described method was successfully used for the study of mitochondrial dysfunction in neuropsychiatric diseases.

Effects of Novel Tacrine Derivatives on Mitochondrial Energy Metabolism and Monoamine Oxidase Activity-In Vitro Study

The trends of novel AD therapeutics are focused on multitarget-directed ligands (MTDLs), which combine cholinesterase inhibition with additional biological properties such as antioxidant properties to positively affect neuronal energy metabolism as well as mitochondrial function. We examined the in vitro effects of 10 novel MTDLs on the activities of mitochondrial enzymes (electron transport chain complexes and citrate synthase), mitochondrial respiration, and monoamine oxidase isoform (MAO-A and MAO-B) activity. The drug-induced effects of 7-MEOTA-adamantylamine heterodimers (K1011, K1013, K1018, K1020, and K1022) and tacrine/7-MEOTA/6-chlorotacrine-trolox heterodimers (K1046, K1053, K1056, K1060, and K1065) were measured in pig brain mitochondria. Most of the substances inhibited complex I- and complex II-linked respiration at high concentrations; K1046, K1053, K1056, and K1060 resulted in the least inhibition of mitochondrial respiration. Citrate synthase activity was not significantly inhibited by the tested substances; the least inhibition of complex I was observed for compounds K1060 and K1053, while both complex II/III and complex IV activity were markedly inhibited by K1011 and K1018. MAO-A was fully inhibited by K1018 and K1065, and MAO-B was fully inhibited by K1053 and K1065; the other tested drugs were partial inhibitors of both MAO-A and MAO-B. The tacrine/7-MEOTA/6-chlorotacrine-trolox heterodimers K1046, K1053, and K1060 seem to be the most suitable molecules for subsequent in vivo studies. These compounds had balanced inhibitory effects on mitochondrial respiration, with low complex I and complex II/III inhibition and full or partial inhibition of MAO-B activity.

Novel Neuroprotective Potential of Crocin in Neurodegenerative Disorders: An Illustrated Mechanistic Review

Neurodegenerative disorders are characterized by mitochondrial dysfunction and subsequently oxidative stress, inflammation, and apoptosis that contribute to neuronal cytotoxicity and degeneration. Recent studies reported that crocin, a carotenoid chemical compound common in crocus and gardenia flowers, has protective effects in neurodegenerative disorders due to its anti-oxidative, anti-inflammatory, and anti-apoptotic properties in the nervous system. This article reviews the new experimental, clinical, and pharmacological studies on the neuroprotective properties of crocin and its potential mechanisms to modulate metabolic oxidative stress and inflammation in neurodegenerative disorders.

Mitochondrial Complex I Is an Essential Player in LPS-Induced Preconditioning in Differentiated PC12 Cells

Preconditioning (PC) as a protective strategy against noxious insults can decline cell death and apoptosis. It has been approved that mitochondria play a key role in PC mechanism. The critical role of complex I (CI) in oxidative phosphorylation machinery and intracellular ROS production, particularly in the brain, accentuates its possible role in PC-induced neuroprotection. Here, differentiated PC12 cells were preconditioned with ultra-low dose LPS (ULD, 3 μg/mL) prior to exposure to high concentration of LPS (HD, 750 μg/mL). Our results showed that HD LPS treatment reduces cell viability and CI activity, and intensifies expression of cleaved caspase 3 compared to the control group. Intriguingly, PC induction resulted in enhancement of cell viability and CI activity and reduction of caspase3 cleavage compared to HD LPS group. In order to explore the role of CI in PC, we combined the ULD LPS with rotenone, a CI inhibitor. Following rotenone administration, cell viability significantly reduced while caspase3 cleavage increased compared to PC induction group. Taken together, cell survival and reduction of apoptosis followed by PC can be at least partially attributed to the preservation of mitochondrial CI function.

Caffeoylquinic Acids with Potential Biological Activity from Plant In vitro Cultures as Alternative Sources of Valuable Natural Products

BACKGROUND

For a long time, the researchers have been looking for new efficient methods to enhance production and obtain valuable plant secondary metabolites, which would contribute to the protection of the natural environment through the preservation of various plant species, often rare and endangered. These possibilities offer plant in vitro cultures which can be performed under strictly-controlled conditions, regardless of the season or climate and environmental factors. Biotechnological methods are promising strategies for obtaining the valuable plant secondary metabolites with various classes of chemical compounds including caffeoylquinic acids (CQAs) and their derivatives. CQAs have been found in many plant species which are components in the daily diet and exhibit a wide spectrum of biological activities, including antioxidant, immunomodulatory, antihypertensive, analgesic, anti-inflammatory, hepato- and neuroprotective, anti-hyperglycemic, anticancer, antiviral and antimicrobial activities. They have also been found to offer protection against Alzheimer's disease, and play a role in weight reduction and lipid metabolism control, as well as modulating the activity of glucose-6-phosphatase involved in glucose metabolism.

METHODS

This work presents the review of the recent advances in use in vitro cultures of various plant species for the alternative system to the production of CQAs and their derivatives. Production of the secondary metabolites in in vitro culture is usually performed with cell suspension or organ cultures, such as shoots and adventitious or transformed roots. To achieve high production of valuable secondary metabolites in in vitro cultures, the optimization of the culture condition is necessary with respect to both biomass accumulation and metabolite content. The optimization of the culture conditions can be achieved by choosing the type of medium, growth regulators or growth conditions, selection of high-productivity lines or culture period, supplementation of the culture medium with precursors or elicitor treatments. Cultivation for large-scale in bioreactors and genetic engineering: Agrobacterium rhizogenes transformation and expression improvement of transcriptional factor or genes involved in the secondary metabolite production pathway are also efficient strategies for enhancement of the valuable secondary metabolites.

RESULTS

Many studies have been reported to obtain highly productive plant in vitro cultures with respect to CQAs. Among these valuable secondary metabolites, the most abundant compound accumulated in in vitro cultures was 5-CQA (chlorogenic acid). Highly productive cultures with respect to this phenolic acid were Leonurus sibiricus AtPAP1 transgenic roots, Lonicera macranthoides and Eucomia ulmoides cell suspension cultures which accumulated above 20 mg g-1 DW 5-CQA. It is known that di- and triCQAs are less common in plants than monoCQAs, but it was also possible to obtain them by biotechnological methods.

CONCLUSION

The results indicate that the various in vitro cultures of different plant species can be a profitable approach for the production of CQAs. In particular, an efficient production of these valuable compounds is possible by Lonicera macranthoides and Eucomia ulmoides cell suspension cultures, Leonurus sibiricus transformed roots and AtPAP1 transgenic roots, Echinacea angustifolia adventitious shoots, Rhaponticum carthamoides transformed plants, Lavandula viridis shoots, Sausera involucrata cell suspension and Cichorium intybus transformed roots.

Developmental Trajectory of Height, Weight, and BMI in Children and Adolescents at Risk for Huntington's Disease: Effect of mHTT on Growth

BACKGROUND

The gene (Huntingtin or HTT) causing Huntington's disease (HD) is vital for development and is expressed throughout the brain and body lifelong. The mutant form (mHTT) may influence growth and development.

OBJECTIVE

To determine the impact of mHTT on human measures of growth, including height, weight, and body mass index (BMI), between child and adolescent carriers of mHTT and control peers.

METHODS

Children ages 6-18 years of age (n = 186) at risk for HD were enrolled in the KidsHD study. For research purposes only, genetic testing was performed to classify participants as Gene-Expanded (GE = 78) or as Gene Non-Expanded (GNE = 108). Outcome measures included height, weight, and body mass index (BMI). Mixed models were used to determine if non-linear age trends differed between groups for BMI, height, and weight.

RESULTS

Differences were seen in the trajectory of BMI in which the GE group reached a plateau in late adolescence with no further increase, compared with a nearly linear increase in the GNE group. There was a significant sex interaction pattern where GE males were taller than GNE males in adolescence, in the presence of similar weight. In contrast, GE females weighed significantly less than their GNE counterparts in adolescence, in the presence of similar height.

CONCLUSION

Measures of growth are abnormal in child and adolescent carriers of mHTT, decades before HD onset. Although further studies are needed for replication, the current findings suggest that developmental aberrations may be systemic and a vital part of disease pathology.

The bimodal mechanism of interaction between dopamine and mitochondria as reflected in Parkinson's disease and in schizophrenia

Parkinson's disease (PD) and schizophrenia (SZ) are two CNS disorders in which dysfunctions in the dopaminergic system and mitochondria are major pathologies. The symptomology of both, PD a neurodegenerative disorder and SZ a neurodevelopmental disorder, is completely different. However, the pharmacological treatment of each of the diseases can cause a shift of symptoms into those characteristic of the other disease. In this review, I describe a pathological interaction between dopamine and mitochondria in both disorders, which due to differences in the extent of oxidative stress leads either to cell death and tissue degeneration as in PD substantia nigra pars compacta or to distorted neuronal activity, imbalanced neuronal circuitry and abnormal behavior and cognition in SZ. This review is in the honor of Moussa Youdim who introduced me to the secrets of research work. His enthusiasm, curiosity and novelty-seeking inspired me throughout my career. Thank you Moussa.

The Protective Effects of Levetiracetam on a Human iPSCs-Derived Spinal Muscular Atrophy Model

Spinal muscular atrophy (SMA) is an inherited disease characterized by progressive motor neuron death and subsequent muscle weakness and is caused by deletion or mutation of survival motor neuron (SMN) 1 gene. Protecting spinal motor neuron is an effective clinical strategy for SMA. The purpose of this study was to investigate the potential effect of an anti-epileptic drug levetiracetam on SMA. In the present study, we used differentiated spinal motor neurons (MNs) from SMA patient-derived induced pluripotent stem cells (SMA-iPSCs) to investigate the effect of levetiracetam. Levetiracetam promoted neurite elongation in SMA-iPSCs-MNs. TUNEL-positive spinal motor neurons were significantly reduced by levetiracetam in SMA-iPSCs-MNs. In addition, the expression level of cleaved-caspase 3 was decreased by levetiracetam in SMA-iPSCs-MNs. Furthermore, levetiracetam improved impaired mitochondrial function in SMA-iPSCs-MNs. On the other hand, levetiracetam did not affect the expression level of SMN protein in SMA-iPSCs-MNs. These findings indicate that levetiracetam has a neuroprotective effect for SMA.

Unravelling protein aggregation as an ageing related process or a neuropathological response

Protein aggregation is normally associated with amyloidosis, namely motor neurone, Alzheimer's, Parkinson's or prion diseases. However, recent results have unveiled a concept of gradual increase of protein aggregation associated with the ageing process, apparently not necessarily associated with pathological conditions. Given that protein aggregation is sufficient to activate stress-response and inflammation, impairing protein synthesis and quality control mechanisms, the former is assumed to negatively affect cellular metabolism and behaviour. In this review the state of the art in protein aggregation research is discussed, namely the relationship between pathology and proteostasis. The role of pathology and ageing in overriding protein quality-control mechanisms, and consequently, the effect of these faulty cellular processes on pathological and healthy ageing, are also addressed.

Biomechanistic insights into the roles of oxidative stress in generating complex neurological disorders

Neurological diseases like Alzheimer's disease, epilepsy, parkinsonism, depression, Huntington's disease and amyotrophic lateral sclerosis prevailing globally are considered to be deeply influenced by oxidative stress-based changes in the biochemical settings of the organs. The excess oxygen concentration triggers the production of reactive oxygen species, and even the intrinsic antioxidant enzyme system, i.e. SOD, CAT and GSHPx, fails to manage their levels and keep them under desirable limits. This consequently leads to oxidation of protein, lipids and nucleic acids in the brain resulting in apoptosis, proteopathy, proteasomes and mitochondrion dysfunction, glial cell activation as well as neuroinflammation. The present exploration deals with the evidence-based mechanism of oxidative stress towards development of key neurological diseases along with the involved biomechanistics and biomaterials.

Mitochondrial DNA haplogroups and age at onset of Machado-Joseph disease/spinocerebellar ataxia type 3: a study in patients from multiple populations

BACKGROUND AND PURPOSE

Mitochondrial dysfunction has been implicated in the pathogenesis of several neurodegenerative disorders, including Machado-Joseph disease (MJD), an autosomal dominant late-onset polyglutamine ataxia that results from an unstable expansion of a CAG tract in the ATXN3 gene. The size of the CAG tract only partially explains age at onset (AO), highlighting the existence of disease modifiers. Mitochondrial DNA (mtDNA) haplogroups have been associated with clinical presentation in other polyglutamine disorders, constituting potential modifiers of MJD phenotype.

METHODS

A cross-sectional study, using 235 unrelated patients from Portugal, Brazil, India and Japan, was performed to investigate if mtDNA haplogroups contribute to AO of MJD. mtDNA haplogroups were obtained after sequencing the mtDNA hypervariable region I. Patients were classified in 15 phylogenetically related haplogroup clusters.

RESULTS

The AO was significantly different among populations, implying the existence of other non-CAG factors, which seem to be population specific. In the Portuguese population, patients classified as belonging to haplogroup JT presented the earliest onset (estimated onset 34.6 years of age). Haplogroups W and X seem to have a protective effect, causing a delay in onset (estimated onset 47 years of age). No significant association between haplogroup clusters and AO was detected in the other populations or when all patients were pooled. Although haplogroup JT has already been implicated in other neurodegenerative disorders, no previous reports of an association between haplogroups W and X and disease were found.

CONCLUSIONS

These findings suggest that haplogroups JT, W and X modify AO in MJD. Replication studies should be performed in European populations, where the frequency of the candidate modifiers is similar.

Mitochondrial dysfunction in the neuro-degenerative and cardio-degenerative disease, Friedreich's ataxia

Mitochondrial homeostasis is essential for maintaining healthy cellular function and survival. The detrimental involvement of mitochondrial dysfunction in neuro-degenerative diseases has recently been highlighted in human conditions, such as Parkinson's, Alzheimer's and Huntington's disease. Friedreich's ataxia (FA) is another neuro-degenerative, but also cardio-degenerative condition, where mitochondrial dysfunction plays a crucial role in disease progression. Deficient expression of the mitochondrial protein, frataxin, is the primary cause of FA, which leads to adverse alterations in whole cell and mitochondrial iron metabolism. Dys-regulation of iron metabolism in these compartments, results in the accumulation of inorganic iron deposits in the mitochondrial matrix that is thought to potentiate oxidative damage observed in FA. Therefore, the maintenance of mitochondrial homeostasis is crucial in the progression of neuro-degenerative conditions, particularly in FA. In this review, vital mitochondrial homeostatic processes and their roles in FA pathogenesis will be discussed. These include mitochondrial iron processing, mitochondrial dynamics (fusion and fission processes), mitophagy, mitochondrial biogenesis, mitochondrial energy production and calcium metabolism.

Mitochondrial Targeted Therapies: Where Do We Stand in Mental Disorders?

The neurobiology of psychiatric disorders is still unclear, although changes in multiple neuronal systems, specifically the dopaminergic, glutamatergic, and gamma-aminobutyric acidergic systems as well as abnormalities in synaptic plasticity and neural connectivity, are currently suggested to underlie their pathophysiology. A growing body of evidence suggests multifaceted mitochondrial dysfunction in mental disorders, which is in line with their role in neuronal activity, growth, development, and plasticity. In this review, we describe the main endeavors toward development of treatments that will enhance mitochondrial function and their transition into clinical use in congenital mitochondrial diseases and chronic disorders such as types 1 and 2 diabetes, cardiovascular disorders, and cancer. In addition, we discuss the relevance of mitochondrial targeted treatments to mental disorders and their potential to become a novel therapeutic strategy that will improve the efficiency of the current treatments.

Degradation of altered mitochondria by autophagy is impaired in Lafora disease

Lafora disease (LD) is a fatal neurodegenerative disorder caused mostly by mutations in either of two genes encoding laforin and malin. LD is characterized by accumulation of a poorly branched form of glycogen in the cytoplasm of neurons and other cells. We previously reported dysfunctional mitochondria in different LD models. Now, using mitochondrial uncouplers and respiratory chain inhibitors, we have investigated with human fibroblasts a possible alteration in the selective degradation of damaged mitochondria (mitophagy) in LD. By flow cytometry of MitoTracker-labelled cells and measuring the levels of various mitochondrial proteins by western blot, we found in LD fibroblasts a partial impairment in the increased mitochondrial degradation produced by these treatments. In addition, colocalization of mitochondrial and lysosomal markers decreased in LD fibroblasts. All these results are consistent with a partial impairment in the induced autophagic degradation of dysfunctional mitochondria in LD fibroblasts. However, canonical recruitment of Parkin to mitochondria under these conditions remained unaffected in LD fibroblasts, and also in SH-SY5Y cells after malin and laforin overexpression. Neither mitochondrial localization nor protein levels of Bcl-2-like protein 13, another component of the mitophagic machinery that operates under these conditions, were affected in LD fibroblasts. In contrast, although these treatments raised autophagy in both control and LD fibroblasts, this enhanced autophagy was clearly lower in the latter cells. Therefore, the autophagic degradation of altered mitochondria is impaired in LD, which is due to a partial defect in the autophagic response and not in the canonical mitophagy signalling pathways.

Monascuspigment rubropunctatin derivative FZU-H reduces Aβ(1-42)-induced neurotoxicity in Neuro-2A cells

Alzheimer's disease (AD) is an extremely complex disease, characterized by several pathological features including oxidative stress and amyloid-β (Aβ) aggregation. Blockage of Aβ-induced injury has emerged as a potential therapeutic approach for AD. Our previous efforts resulted in the discovery of Monascus pigment rubropunctatin derivative FZU-H with potential neuroprotective effects. This novel lead compound significantly diminishes toxicity induced by Aβ(1-42) in Neuro-2A cells. Our further mechanism investigation revealed that FZU-H inhibited Aβ(1-42)-induced caspase-3 protein activation and the loss of mitochondrial membrane potential. In addition, treatment of FZU-H was proven to attenuate Aβ(1-42)-induced cell redox imbalance and Tau hyperphosphorylation which caused by okadaic acid in Neuro-2A cells. These results indicated that FZU-H shows promising neuroprotective effects for AD.

Monascus pigment rubropunctatin derivative FZU-H shows promising neuroprotective effects for AD.

Postmortem studies on mitochondria in schizophrenia

The aim of this paper is to provide a brief review of mitochondrial structure as it relates to function and then present abnormalities in mitochondria in postmortem schizophrenia with a focus on ultrastructure. Function, morphology, fusion, fission, motility, ΔΨmem, ATP production, mitochondrial derived vesicles, and mitochondria-associated ER membranes will be briefly covered. Pathology in mitochondria has long been implicated in schizophrenia, as shown by genetic, proteomic, enzymatic and anatomical abnormalities. The cortex and basal ganglia will be reviewed. In the anterior cingulate cortex, the number of mitochondria per neuronal somata in layers 5/6 in schizophrenia is decreased by 43%. There are also fewer mitochondria in terminals forming axospinous synapses. In the caudate and putamen the number of mitochondria is abnormal in both glial cells and neurons in schizophrenia subjects, the extent of which depends on treatment, response and predominant lifetime symptoms. Treatment-responsive schizophrenia subjects had about a 40% decrease in the number of mitochondria per synapse in the caudate nucleus and putamen, while treatment resistant cases had normal values. A decrease in mitochondrial density in the neuropil distinguishes paranoid from undifferentiated schizophrenia. The appearance, size and density of mitochondria were normal in the nucleus accumbens. In the substantia nigra, COX subunits were affected in rostral regions. Mitochondrial hyperplasia occurs within axon terminals that synapse onto dopamine neurons, but mitochondria in dopamine neuronal somata are similar in size and number. In schizophrenia, mitochondria are differentially affected depending on the brain region, cell type, subcellular location, treatment status, treatment response and symptoms.

The unintended mitochondrial uncoupling effects of the FDA-approved anti-helminth drug nitazoxanide mitigates experimental parkinsonism in mice

Mitochondria play a primary role in the pathophysiology of Parkinson's disease (PD), and small molecules that counteract the initial stages of disease may offer therapeutic benefit. In this regard, we have examined whether the off-target effects of the Food and Drug Administration (FDA)-approved anti-helminth drug nitazoxanide (NTZ) on mitochondrial respiration could possess any therapeutic potential for PD. Results indicate that MPP⁺-induced loss in oxygen consumption rate (OCR) and ATP production by mitochondria were ameliorated by NTZ in real time by virtue of its mild uncoupling effect. Pretreatment of cells with NTZ mitigated MPP⁺-induced loss in mitochondrial OCR and reactive oxygen species (ROS). Similarly, addition of NTZ to cells pretreated with MPP⁺ could reverse block in mitochondrial OCR and reactive oxygen species induced by MPP⁺ in real time. The observed effects of NTZ were found to be transient and reversible as removal of NTZ from incubation medium restored the mitochondrial respiration to that of controls. Apoptosis induced by MPP⁺ was ameliorated by NTZ in a dose-dependent manner. In vivo results demonstrated that oral administration of NTZ (50 mg/kg) in an acute MPTP mouse model of PD conferred significant protection against the loss of tyrosine hydroxylase (TH)-positive neurons of substantia nigra. Based on the above observations we believe that repurposing of NTZ for PD may offer therapeutic benefit.

Friedreich's ataxia induced pluripotent stem cell-derived cardiomyocytes display electrophysiological abnormalities and calcium handling deficiency

We sought to identify the impacts of Friedreich's ataxia (FRDA) on cardiomyocytes. FRDA is an autosomal recessive degenerative condition with neuronal and non-neuronal manifestations, the latter including progressive cardiomyopathy of the left ventricle, the leading cause of death in FRDA. Little is known about the cellular pathogenesis of FRDA in cardiomyocytes. Induced pluripotent stem cells (iPSCs) were derived from three FRDA individuals with characterized GAA repeats. The cells were differentiated into cardiomyocytes to assess phenotypes. FRDA iPSC- cardiomyocytes retained low levels of FRATAXIN (FXN) mRNA and protein. Electrophysiology revealed an increased variation of FRDA- cardiomyocyte beating rates which was prevented by addition of nifedipine, suggestive of a calcium handling deficiency. Finally, calcium imaging was performed and we identified small amplitude, diastolic and systolic calcium transients confirming a deficiency in calcium handling. We defined a robust FRDA cardiac-specific electrophysiological profile in patient-derived iPSCs which could be used for high throughput compound screening. This cell-specific signature will contribute to the identification and screening of novel treatments for this life-threatening disease.

Genetic ablation of the p66Shc adaptor protein reverses cognitive deficits and improves mitochondrial function in an APP transgenic mouse model of Alzheimer's disease

The mammalian ShcA adaptor protein p66^Shc is a key regulator of mitochondrial reactive oxygen species (ROS) production and has previously been shown to mediate amyloid β (Aβ)-peptide-induced cytotoxicity in vitro. Moreover, p66^Shc is involved in mammalian longevity and lifespan determination as revealed in the p66^Shc knockout mice, which are characterized by a 30% prolonged lifespan, lower ROS levels and protection from age-related impairment of physical and cognitive performance. In this study, we hypothesized a role for p66^Shc in Aβ-induced toxicity in vivo and investigated the effects of genetic p66^Shc deletion in the PSAPP transgenic mice, an established Alzheimer's disease mouse model of β-amyloidosis. p66^Shc-ablated PSAPP mice were characterized by an improved survival and a complete rescue of Aβ-induced cognitive deficits at the age of 15 months. Importantly, these beneficial effects on survival and cognitive performance were independent of Aβ levels and amyloid plaque deposition, but were associated with improved brain mitochondrial respiration, a reversal of mitochondrial complex I dysfunction, restored adenosine triphosphate production and reduced ROS levels. The results of this study support a role for p66^Shc in Aβ-related mitochondrial dysfunction and oxidative damage in vivo, and suggest that p66^Shc ablation may be a promising novel therapeutic strategy against Aβ-induced toxicity and cognitive impairment.

Aβ42 oligomers modulate β-secretase through an XBP-1s-dependent pathway involving HRD1

The aspartyl protease β-site APP cleaving enzyme, BACE1, is the rate-limiting enzyme involved in the production of amyloid-β peptide, which accumulates in both sporadic and familial cases of Alzheimer’s disease and is at the center of gravity of the amyloid cascade hypothesis. In this context, unravelling the molecular mechanisms controlling BACE1 expression and activity in both physiological and pathological conditions remains of major importance. We previously demonstrated that Aβ controlled BACE1 transcription in an NFκB-dependent manner. Here, we delineate an additional cellular pathway by which natural and synthetic Aβ42 oligomers enhance active X-box binding protein XBP-1s. XBP-1s lowers BACE1 expression and activity indirectly, via the up-regulation of the ubiquitin-ligase HRD1 that acts as an endogenous down-regulator of BACE1. Thus, we delineate a novel pathway by which cells could compensate for Aβ42 oligomers production and thus, associated toxicity, by triggering a compensatory mechanism aimed at lowering BACE-1-mediated Aβ production by a molecular cascade involving XBP-1s and HRD1. It thus identifies HRD1 as a potential target for a novel Aβ-centered therapeutic strategy.

Insulin signalling in Alzheimer's disease and diabetes: from epidemiology to molecular links

As populations across the world both age and become more obese, the numbers of individuals with Alzheimer's disease and diabetes are increasing; posing enormous challenges for society and consequently becoming priorities for governments and global organizations. These issues, an ageing population at risk of neurodegenerative diseases such as Alzheimer's disease and an increasingly obese population at risk of metabolic alterations such as type 2 diabetes, are usually considered as independent conditions, but increasing evidence from both epidemiological and molecular studies link these disorders. The aim of this review was to highlight these multifactorial links. We will discuss the impact of direct links between insulin and IGF-1 signalling and the Alzheimer's disease-associated pathological events as well as the impact of other processes such as inflammation, oxidative stress and mitochondrial dysfunction either common to both conditions or perhaps responsible for a mechanistic link between metabolic and neurodegenerative disease. An understanding of such associations might be of importance not only in the understanding of disease mechanisms but also in the search for novel therapeutic options.

Low-Level Laser Irradiation Improves Depression-Like Behaviors in Mice

Major depressive disorder (MDD) is one of the leading forms of psychiatric disorders, characterized by aversion to mobility, neurotransmitter deficiency, and energy metabolic decline. Low-level laser therapy (LLLT) has been investigated in a variety of neurodegenerative disorders associated with mitochondrial dysfunction and functional impairments. The goal of this study was to examine the effect of LLLT on depression-like behaviors and to explore the potential mechanism by detecting mitochondrial function following LLLT. Depression models in space restriction mice and Abelson helper integration site-1 (Ahi1) knockout (KO) mice were employed in this work. Our results revealed that LLLT effectively improved depression-like behaviors, in the two depression mice models, by decreasing immobility duration in behavioral despair tests. In addition, ATP biosynthesis and the level of mitochondrial complex IV expression and activity were significantly elevated in prefrontal cortex (PFC) following LLLT. Intriguingly, LLLT has no effects on ATP content and mitochondrial complex I-IV levels in other tested brain regions, hippocampus and hypothalamus. As a whole, these findings shed light on a novel strategy of transcranial LLLT on depression improvement by ameliorating neurotransmitter abnormalities and promoting mitochondrial function in PFC. The present work provides concrete groundwork for further investigation of LLLT for depression treatment.

Characterization of mitochondrial function in cells with impaired cystic fibrosis transmembrane conductance regulator (CFTR) function

Evidence supporting the occurrence of oxidative stress in Cystic Fibrosis (CF) is well established and the literature suggests that oxidative stress is inseparably linked to mitochondrial dysfunction. Here, we have characterized mitochondrial function, in particular as it regards the steps of oxidative phosphorylation and ROS production, in airway cells either homozygous for the F508del-CFTR allele or stably expressing wt-CFTR. We find that oxygen consumption, ΔΨ generation, adenine nucleotide translocator-dependent ADP/ATP exchange and both mitochondrial Complex I and IV activities are impaired in CF cells, while both mitochondrial ROS production and membrane lipid peroxidation increase. Importantly, treatment of CF cells with the small molecules VX-809 and 4,6,4'-trimethylangelicin, which act as "correctors" for F508del CFTR by rescuing the F508del CFTR-dependent chloride secretion, while having no effect per sè on mitochondrial function in wt-CFTR cells, significantly improved all the above mitochondrial parameters towards values found in the airway cells expressing wt-CFTR. This novel study on mitochondrial bioenergetics provides a springboard for future research to further understand the molecular mechanisms responsible for the involvement of mitochondria in CF and identify the proteins primarily responsible for the F508del-CFTR-dependent mitochondrial impairment and thus reveal potential novel targets for CF therapy.

Dorsal Anterior Cingulate Lactate and Glutathione Levels in Euthymic Bipolar I Disorder: 1H-MRS Study

OBJECTIVE

Oxidative stress and mitochondrial dysfunction are 2 closely integrated processes implicated in the physiopathology of bipolar disorder. Advanced proton magnetic resonance spectroscopy techniques enable the measurement of levels of lactate, the main marker of mitochondrial dysfunction, and glutathione, the predominant brain antioxidant. The objective of this study was to measure brain lactate and glutathione levels in bipolar disorder and healthy controls.

METHODS

Eighty-eight individuals (50 bipolar disorder and 38 healthy controls) underwent 3T proton magnetic resonance spectroscopy in the dorsal anterior cingulate cortex (2x2x4.5cm(3)) using a 2-D JPRESS sequence. Lactate and glutathione were quantified using the ProFit software program.

RESULTS

Bipolar disorder patients had higher dorsal anterior cingulate cortex lactate levels compared with controls. Glutathione levels did not differ between euthymic bipolar disorder and controls. There was a positive correlation between lactate and glutathione levels specific to bipolar disorder. No influence of medications on metabolites was observed.

CONCLUSION

This is the most extensive magnetic resonance spectroscopy study of lactate and glutathione in bipolar disorder to date, and results indicated that euthymic bipolar disorder patients had higher levels of lactate, which might be an indication of altered mitochondrial function. Moreover, lactate levels correlated with glutathione levels, indicating a compensatory mechanism regardless of bipolar disorder diagnosis.

Old Things New View: Ascorbic Acid Protects the Brain in Neurodegenerative Disorders

Ascorbic acid is a key antioxidant of the Central Nervous System (CNS). Under brain activity, ascorbic acid is released from glial reservoirs to the synaptic cleft, where it is taken up by neurons. In neurons, ascorbic acid scavenges reactive oxygen species (ROS) generated during synaptic activity and neuronal metabolism where it is then oxidized to dehydroascorbic acid and released into the extracellular space, where it can be recycled by astrocytes. Other intrinsic properties of ascorbic acid, beyond acting as an antioxidant, are important in its role as a key molecule of the CNS. Ascorbic acid can switch neuronal metabolism from glucose consumption to uptake and use of lactate as a metabolic substrate to sustain synaptic activity. Multiple evidence links oxidative stress with neurodegeneration, positioning redox imbalance and ROS as a cause of neurodegeneration. In this review, we focus on ascorbic acid homeostasis, its functions, how it is used by neurons and recycled to ensure antioxidant supply during synaptic activity and how this antioxidant is dysregulated in neurodegenerative disorders.

Investigation of mitochondrial DNA variations among Indian Friedreich's ataxia (FRDA) patients

OBJECTIVE

The loss of function mutations (biallelic) in frataxin (FXN) has primarily been implicated in Friedreich's ataxia (FRDA), an autosomal recessive cerebellar ataxia. The protein product of FXN is a nuclear-encoded mitochondrial protein required for the biogenesis of iron- clusters (Fe-S). FRDA is characterized by neurological and non-neurological features which show variable expression in affected individuals. An inverse relationship has been demonstrated between GAA repeat size and age at onset and explains 50% variability of the age at onset. MtDNA variations and haplogroups could be one of the contributory factors to explain the remaining heterogeneity in FRDA, since mitochondrial oxidative stress is thought to be involved in the pathogenesis of FRDA.

METHODS

In our study, targeted resequencing of the D-loop and coding region of mitochondrial genes (ND1-6 and ATP) was conducted in 30 genetically confirmed FRDA patients and 62 ethnicity-matched unrelated healthy controls to identify the functionally important mtDNA variations and to trace the mitochondrial lineage of Indian FRDA patients. Cumulative mitochondrial SNP scores were computed for the identified variations in the functional region and haplogroups were determined by Haplogrep.

RESULTS

A significantly higher load of overall mitochondrial variations (with a trend toward the coding region) per individual was noted among FRDA cases rather than controls (p-value<0.03). A non-synonymous variation (p. L237M) in ND2 was over-represented among FRDA cases (p-value 0.04). This variation has a reported association with longevity and myocardial infarction. We also observed over-representation of H haplogroup (Caucasian mitochondrial haplogroup) among FRDA patients. We have not observed the influence of mitochondrial variations and haplogroup upon age at onset of FRDA.

CONCLUSIONS

Overall, our study identifies the functionally important variations and mitochondrial lineage of Indian FRDA cases and, that underscores the importance of studying the role of mitochondrial genome variations in FRDA.

Intracellular Dynamics of Synucleins: "Here, There and Everywhere"

Synucleins are small, soluble proteins expressed primarily in neural tissue and in certain tumors. The synuclein family consists of three members: α-, β-, and γ-synucleins present only in vertebrates. Members of the synuclein family have high sequence identity, especially in the N-terminal regions. The synuclein gene family came into the spotlight, when one of its members, α-synuclein, was found to be associated with Parkinson's disease and other neurodegenerative disorders, whereas γ-synuclein was linked to several forms of cancer. There are a lot of controversy and exciting debates concerning members of the synuclein family, including their normal functions, toxicity, role in pathology, transmission between cells and intracellular localization. Important findings which remain undisputable for many years are synuclein localization in synapses and their role in the regulation of synaptic vesicle trafficking, whereas their presence and function in mitochondria and nucleus is a debated topic. In this review, we present the data on the localization of synucleins in two intracellular organelles: the nucleus and mitochondria.

Mitochondria-focused gene expression profile reveals common pathways and CPT1B dysregulation in both rodent stress model and human subjects with PTSD

Posttraumatic stress disorder (PTSD), a trauma-related mental disorder, is associated with mitochondrial dysfunction in the brain. However, the biologic approach to identifying the mitochondria-focused genes underlying the pathogenesis of PTSD is still in its infancy. Previous research, using a human mitochondria-focused cDNA microarray (hMitChip3) found dysregulated mitochondria-focused genes present in postmortem brains of PTSD patients, indicating that those genes might be PTSD-related biomarkers. To further test this idea, this research examines profiles of mitochondria-focused gene expression in the stressed-rodent model (inescapable tail shock in rats), which shows characteristics of PTSD-like behaviors and also in the blood of subjects with PTSD. This study found that 34 mitochondria-focused genes being upregulated in stressed-rat amygdala. Ten common pathways, including fatty acid metabolism and peroxisome proliferator-activated receptors (PPAR) pathways were dysregulated in the amygdala of the stressed rats. Carnitine palmitoyltransferase 1B (CPT1B), an enzyme in the fatty acid metabolism and PPAR pathways, was significantly over-expressed in the amygdala (P < 0.007) and in the blood (P < 0.01) of stressed rats compared with non-stressed controls. In human subjects with (n = 28) or without PTSD (n = 31), significant over-expression of CPT1B in PTSD was also observed in the two common dysregulated pathways: fatty acid metabolism (P = 0.0027, false discovery rate (FDR) = 0.043) and PPAR (P = 0.006, FDR = 0.08). Quantitative real-time polymerase chain reaction validated the microarray findings and the CPT1B result. These findings indicate that blood can be used as a specimen in the search for PTSD biomarkers in fatty acid metabolism and PPAR pathways, and, in addition, that CPT1B may contribute to the pathology of PTSD.

Modulation of mitochondrial complex I activity averts cognitive decline in multiple animal models of familial Alzheimer's Disease

Development of therapeutic strategies to prevent Alzheimer's Disease (AD) is of great importance. We show that mild inhibition of mitochondrial complex I with small molecule CP2 reduces levels of amyloid beta and phospho-Tau and averts cognitive decline in three animal models of familial AD. Low-mass molecular dynamics simulations and biochemical studies confirmed that CP2 competes with flavin mononucleotide for binding to the redox center of complex I leading to elevated AMP/ATP ratio and activation of AMP-activated protein kinase in neurons and mouse brain without inducing oxidative damage or inflammation. Furthermore, modulation of complex I activity augmented mitochondrial bioenergetics increasing coupling efficiency of respiratory chain and neuronal resistance to stress. Concomitant reduction of glycogen synthase kinase 3β activity and restoration of axonal trafficking resulted in elevated levels of neurotrophic factors and synaptic proteins in adult AD mice. Our results suggest metabolic reprogramming induced by modulation of mitochondrial complex I activity represents promising therapeutic strategy for AD.

Assessment of cytochrome C oxidase dysfunction in the substantia nigra/ventral tegmental area in schizophrenia

Perturbations in metabolism are a well-documented but complex facet of schizophrenia pathology. Optimal cellular performance requires the proper functioning of the electron transport chain, which is constituted by four enzymes located within the inner membrane of mitochondria. These enzymes create a proton gradient that is used to power the enzyme ATP synthase, producing ATP, which is crucial for the maintenance of cellular functioning. Anomalies in a single enzyme of the electron transport chain are sufficient to cause disruption of cellular metabolism. The last of these complexes is the cytochrome c oxidase (COX) enzyme, which is composed of thirteen different subunits. COX is a major site for oxidative phosphorylation, and anomalies in this enzyme are one of the most frequent causes of mitochondrial pathology. The objective of the present report was to assess if metabolic anomalies linked to COX dysfunction may contribute to substantia nigra/ventral tegmental area (SN/VTA) pathology in schizophrenia. We tested COX activity in postmortem SN/VTA from schizophrenia and non-psychiatric controls. We also tested the protein expression of key subunits for the assembly and activity of the enzyme, and the effect of antipsychotic medication on subunit expression. COX activity was not significantly different between schizophrenia and non-psychiatric controls. However, we found significant decreases in the expression of subunits II and IV-I of COX in schizophrenia. Interestingly, these decreases were observed in samples containing the entire rostro-caudal extent of the SN/VTA, while no significant differences were observed for samples containing only mid-caudal regions of the SN/VTA. Finally, rats chronically treated with antipsychotic drugs did not show significant changes in COX subunit expression. These findings suggest that COX subunit expression may be compromised in specific sub-regions of the SN/VTA (i.e. rostral regions), which may lead to a faulty assembly of the enzyme and a greater vulnerability to metabolic insult.

Elevated risk of type 2 diabetes for development of Alzheimer disease: a key role for oxidative stress in brain

Alzheimer disease (AD) is the most common form of dementia among the elderly and is characterized by progressive loss of memory and cognition. Epidemiological data show that the incidence of AD increases with age and doubles every 5 years after 65 years of age. From a neuropathological point of view, amyloid-β-peptide (Aβ) leads to senile plaques, which, together with hyperphosphorylated tau-based neurofibrillary tangles and synapse loss, are the principal pathological hallmarks of AD. Aβ is associated with the formation of reactive oxygen (ROS) and nitrogen (RNS) species, and induces calcium-dependent excitotoxicity, impairment of cellular respiration, and alteration of synaptic functions associated with learning and memory. Oxidative stress was found to be associated with type 2 diabetes mellitus (T2DM), which (i) represents another prevalent disease associated with obesity and often aging, and (ii) is considered to be a risk factor for AD development. T2DM is characterized by high blood glucose levels resulting from increased hepatic glucose production, impaired insulin production and peripheral insulin resistance, which close resemble to the brain insulin resistance observed in AD patients. Furthermore, growing evidence suggests that oxidative stress plays a pivotal role in the development of insulin resistance and vice versa. This review article provides molecular aspects and the pharmacological approaches from both preclinical and clinical data interpreted from the point of view of oxidative stress with the aim of highlighting progresses in this field.

Delivering healthy mitochondria for the therapy of mitochondrial diseases and beyond

Mitochondrial transfer has been demonstrated to a play a physiological role in the rescuing of mitochondrial DNA deficient cells by co-culture with human mesenchymal stem cells. The successful replacement of mitochondria using microinjection into the embryo has been revealed to improve embryo maturation. Evidence of mitochondrial transfer has been shown to minimize injury of the ischemic-reperfusion rabbit heart model. In this mini review, the therapeutic strategies of mitochondrial diseases based on the concept of mitochondrial transfer are illustrated, as well as a novel approach to peptide-mediated mitochondrial delivery. The possible mechanism of peptide-mediated mitochondrial delivery in the treatment of the myoclonic epilepsy and ragged-red fiber disease is summarized. Understanding the feasibility of mitochondrial manipulation in cells facilitates novel therapeutic skills in the future clinical practice of mitochondrial disorder.

Mitochondrial dysfunctions in neurodegenerative diseases: relevance to Alzheimer's disease

Mitochondrial dysfunctions are supposed to be responsible for many neurodegenerative diseases dominating in Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). A growing body of evidence suggests that defects in mitochondrial metabolism and particularly of electron transport chain may play a role in pathogenesis of AD. Structurally and functionally damaged mitochondria do not produce sufficient ATP and are more prominent in producing proapoptotic factors and reactive oxygen species (ROS), and this can be an early stage of several mitochondrial disorders, including neurodegenerative diseases. Mitochondrial dysfunctions may be caused by both mutations in mitochondrial or nuclear DNA that code mitochondrial components and by environmental causes. In the following review, common aspects of mitochondrial impairment concerned about neurodegenerative diseases are summarized including ROS production, impaired mitochondrial dynamics, and apoptosis. Also, damaged function of electron transport chain complexes and interactions between pathological proteins and mitochondria are described for AD particularly and marginally for PD and HD.