MitoQ, a mitochondria-targeted antioxidant, delays disease progression and alleviates pathogenesis in an experimental autoimmune encephalomyelitis mouse model of multiple sclerosis.

Oxidative stress and mitochondrial dysfunction are involved in the progression and pathogenesis of multiple sclerosis (MS). MitoQ is a mitochondria-targeted antioxidant that has a neuroprotective role in several mitochondrial and neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Here we sought to determine the possible effects of a systematic administration of MitoQ as a therapy, using an experimental autoimmune encephalomyelitis (EAE) mouse model. We studied the beneficial effects of MitoQ in EAE mice that mimic MS like symptoms by treating EAE mice with MitoQ and pretreated C57BL6 mice with MitoQ plus EAE induction. We found that pretreatment and treatment of EAE mice with MitoQ reduced neurological disabilities associated with EAE. We also found that both pretreatment and treatment of the EAE mice with MitoQ significantly suppressed inflammatory markers of EAE, including the inhibition of inflammatory cytokines and chemokines. MitoQ treatments reduced neuronal cell loss in the spinal cord, a factor underlying motor disability in EAE mice. The neuroprotective role of MitoQ was confirmed by a neuron-glia co-culture system designed to mimic the mechanism of MS and EAE in vitro. We found that axonal inflammation and oxidative stress are associated with impaired behavioral functions in the EAE mouse model and that treatment with MitoQ can exert protective effects on neurons and reduce axonal inflammation and oxidative stress. These protective effects are likely via multiple mechanisms, including the attenuation of the robust immune response. These results suggest that MitoQ may be a new candidate for the treatment of MS.

Mutant huntingtin's interaction with mitochondrial protein Drp1 impairs mitochondrial biogenesis and causes defective axonal transport and synaptic degeneration in Huntington's disease.

The purpose of this study was to investigate the link between mutant huntingtin (Htt) and neuronal damage in relation to mitochondria in Huntington's disease (HD). In an earlier study, we determined the relationship between mutant Htt and mitochondrial dynamics/synaptic viability in HD patients. We found mitochondrial loss, abnormal mitochondrial dynamics and mutant Htt association with mitochondria in HD patients. In the current study, we sought to expand on our previous findings and further elucidate the relationship between mutant Htt and mitochondrial and synaptic deficiencies. We hypothesized that mutant Htt, in association with mitochondria, alters mitochondrial dynamics, leading to mitochondrial fragmentation and defective axonal transport of mitochondria in HD neurons. In this study, using postmortem HD brains and primary neurons from transgenic BACHD mice, we identified mutant Htt interaction with the mitochondrial protein Drp1 and factors that cause abnormal mitochondrial dynamics, including GTPase Drp1 enzymatic activity. Further, using primary neurons from BACHD mice, for the first time, we studied axonal transport of mitochondria and synaptic degeneration. We also investigated the effect of mutant Htt aggregates and oligomers in synaptic and mitochondrial deficiencies in postmortem HD brains and primary neurons from BACHD mice. We found that mutant Htt interacts with Drp1, elevates GTPase Drp1 enzymatic activity, increases abnormal mitochondrial dynamics and results in defective anterograde mitochondrial movement and synaptic deficiencies. These observations support our hypothesis and provide data that can be utilized to develop therapeutic targets that are capable of inhibiting mutant Htt interaction with Drp1, decreasing mitochondrial fragmentation, enhancing axonal transport of mitochondria and protecting synapses from toxic insults caused by mutant Htt.

Mitochondria-targeted catalase reduces abnormal APP processing, amyloid ß production and BACE1 in a mouse model of Alzheimer's disease: implications for neuroprotection and lifespan extension.

The purpose of this study was to investigate the protective effects of the mitochondria-targeted antioxidant catalase (MCAT) and lifespan extension in mice that express amyloid beta (Aß). Using immunoblotting and immunostaining analyses, we measured the production of full-length amyloid precursor protein (APP), soluble APPα, C-terminal fragments CTF99 and CTF83, monomeric and oligomeric Aß, Aß deposits and beta site amyloid precursor protein cleaving enzyme 1 (BACE1), in different stages of disease progression in MCAT/AßPP and AßPP mice. Using quantitative reverse transcriptase polymerase chain reaction and immunostaining analyses, we studied the expression of catalase, BACE1, the Alzheimer's disease (AD) markers, synaptophysin, APP, neprilysin, insulin-degrading enzyme and transthyretin in MCAT, AßPP, MCAT/AßPP and wild-type (WT) mice. Using the high pressure liquid chromatography analysis of 8-hydroxy-2-deoxyguanosine, we measured oxidative DNA damage in the cerebral cortical tissues from MCAT, AßPP, MCAT/AßPP and WT mice. We found that the AßPP transgenic mice that carried the human MCAT gene lived 5 months longer than did the AßPP mice. We also found that the overexpression of MCAT in the brain sections from the MCAT/AßPP transgenic mice significantly correlated with a reduction in the levels of full-length APP, CTF99, BACE1, Aß levels (40 and 42), Aß deposits and oxidative DNA damage relative to the brain sections from the AßPP mice. Interestingly, we found significantly increased levels of soluble APPα and CTF83 in the MCAT/AßPP mice, relative to the AßPP mice. These data provide direct evidence that oxidative stress plays a primary role in AD etiopathology and that in MCAT mice express Aß, MCAT prevents abnormal APP processing, reduces Aß levels and enhances Aß-degrading enzymes in mice at different ages, corresponding to different stages of disease progression. These findings indicate that mitochondria-targeted molecules may be an effective therapeutic approach to treat patients with AD.

Mutant huntingtin, abnormal mitochondrial dynamics, defective axonal transport of mitochondria, and selective synaptic degeneration in Huntington's disease.

Huntington's disease (HD) is a progressive, fatal neurodegenerative disease caused by expanded polyglutamine repeats in the HD gene. HD is characterized by chorea, seizures, involuntary movements, dystonia, cognitive decline, intellectual impairment and emotional disturbances. Research into mutant huntingtin (Htt) and mitochondria has found that mutant Htt interacts with the mitochondrial protein dynamin-related protein 1 (Drp1), enhances GTPase Drp1 enzymatic activity, and causes excessive mitochondrial fragmentation and abnormal distribution, leading to defective axonal transport of mitochondria and selective synaptic degeneration. This article summarizes latest developments in HD research and focuses on the role of abnormal mitochondrial dynamics and defective axonal transport in HD neurons. This article also discusses the therapeutic strategies that decrease mitochondrial fragmentation and neuronal damage in HD.

Mitochondrial DNA deletions and differential mitochondrial DNA content in Rhesus monkeys: implications for aging.

The purpose of this study was to determine the relationship between mitochondrial DNA (mtDNA) deletions, mtDNA content and aging in rhesus monkeys. Using 2 sets of specific primers, we amplified an 8 kb mtDNA fragment covering a common 5.7 kb deletion and the entire 16.5 kb mitochondrial genome in the brain and buffy-coats of young and aged monkeys. We studied a total of 66 DNA samples: 39 were prepared from a buffy-coat and 27 were prepared from occipital cortex tissues. The mtDNA data were assessed using a permutation test to identify differences in mtDNA, in the different monkey groups. Using real-time RT-PCR strategy, we also assessed both mtDNA and nuclear DNA levels for young, aged and male and female monkeys. We found a 5.7 kb mtDNA deletion in 81.8% (54 of 66) of the total tested samples. In the young group of buffy-coat DNA, we found 5.7 kb deletions in 7 of 17 (41%), and in the aged group, we found 5.7 kb deletions in 12 of 22 (54%), suggesting that the prevalence of mtDNA deletions is related to age. We found decreased mRNA levels of mtDNA in aged monkeys relative to young monkeys. The increases in mtDNA deletions and mtDNA levels in aged rhesus monkeys suggest that damaged DNA accumulates as rhesus monkeys age and these altered mtDNA changes may have physiological relevance to compensate decreased mitochondrial function.

Abnormal mitochondrial dynamics and synaptic degeneration as early events in Alzheimer's disease: implications to mitochondria-targeted antioxidant therapeutics.

Synaptic pathology and mitochondrial oxidative damage are early events in Alzheimer's disease (AD) progression. Loss of synapses and synaptic damage are the best correlates of cognitive deficits found in AD patients. Recent research on amyloid beta (Aß) and mitochondria in AD revealed that Aß accumulates in synapses and synaptic mitochondria, leading to abnormal mitochondrial dynamics and synaptic degeneration in AD neurons. Further, recent studies using live-cell imaging and primary neurons from amyloid beta precursor protein (AßPP) transgenic mice revealed reduced mitochondrial mass, defective axonal transport of mitochondria and synaptic degeneration, indicating that Aß is responsible for mitochondrial and synaptic deficiencies. Tremendous progress has been made in studying antioxidant approaches in mouse models of AD and clinical trials of AD patients. This article highlights the recent developments made in Aß-induced abnormal mitochondrial dynamics, defective mitochondrial biogenesis, impaired axonal transport and synaptic deficiencies in AD. This article also focuses on mitochondrial approaches in treating AD, and also discusses latest research on mitochondria-targeted antioxidants in AD. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Impaired mitochondrial biogenesis, defective axonal transport of mitochondria, abnormal mitochondrial dynamics and synaptic degeneration in a mouse model of Alzheimer's disease.

Increasing evidence suggests that the accumulation of amyloid beta (Aß) in synapses and synaptic mitochondria causes synaptic mitochondrial failure and synaptic degeneration in Alzheimer's disease (AD). The purpose of this study was to better understand the effects of Aß in mitochondrial activity and synaptic alterations in neurons from a mouse model of AD. Using primary neurons from a well-characterized Aß precursor protein transgenic (AßPP) mouse model (Tg2576 mouse line), for the first time, we studied mitochondrial activity, including axonal transport of mitochondria, mitochondrial dynamics, morphology and function. Further, we also studied the nature of Aß-induced synaptic alterations, and cell death in primary neurons from Tg2576 mice, and we sought to determine whether the mitochondria-targeted antioxidant SS31 could mitigate the effects of oligomeric Aß. We found significantly decreased anterograde mitochondrial movement, increased mitochondrial fission and decreased fusion, abnormal mitochondrial and synaptic proteins and defective mitochondrial function in primary neurons from AßPP mice compared with wild-type (WT) neurons. Transmission electron microscopy revealed a large number of small mitochondria and structurally damaged mitochondria, with broken cristae in AßPP primary neurons. We also found an increased accumulation of oligomeric Aß and increased apoptotic neuronal death in the primary neurons from the AßPP mice relative to the WT neurons. Our results revealed an accumulation of intraneuronal oligomeric Aß, leading to mitochondrial and synaptic deficiencies, and ultimately causing neurodegeneration in AßPP cultures. However, we found that the mitochondria-targeted antioxidant SS31 restored mitochondrial transport and synaptic viability, and decreased the percentage of defective mitochondria, indicating that SS31 protects mitochondria and synapses from Aß toxicity.

Abnormal mitochondrial dynamics, mitochondrial loss and mutant huntingtin oligomers in Huntington's disease: implications for selective neuronal damage.

The purpose of our study was to determine the relationship between mutant huntingtin (Htt) and mitochondrial dynamics in the progression of Huntington's disease (HD). We measured the mRNA levels of electron transport chain genes, and mitochondrial structural genes, Drp1 (dynamin-related protein 1), Fis1 (fission 1), Mfn1 (mitofusin 1), Mfn2 (mitofusin 2), Opa1 (optric atrophy 1), Tomm40 (translocase of outermembrane 40) and CypD (cyclophilin D) in grade III and grade IV HD patients and controls. The mutant Htt oligomers and the mitochondrial structural proteins were quantified in the striatum and frontal cortex of HD patients. Changes in expressions of the electron transport chain genes were found in HD patients and may represent a compensatory response to mitochondrial damage caused by mutant Htt. Increased expression of Drp1 and Fis1 and decreased expression of Mfn1, Mfn2, Opa1 and Tomm40 were found in HD patients relative to the controls. CypD was upregulated in HD patients, and this upregulation increased as HD progressed. Significantly increased immunoreactivity of 8-hydroxy-guanosine was found in the cortical specimens from stage III and IV HD patients relative to controls, suggesting increased oxidative DNA damage in HD patients. In contrast, significantly decreased immunoreactivities of cytochrome oxidase 1 and cytochrome b were found in HD patients relative to controls, indicating a loss of mitochondrial function in HD patients. Immunoblotting analysis revealed 15, 25 and 50 kDa mutant Htt oligomers in the brain specimens of HD patients. All oligomeric forms of mutant Htt were significantly increased in the cortical tissues of HD patients, and mutant Htt oligomers were found in the nucleus and in mitochondria. The increase in Drp1, Fis1 and CypD and the decrease in Mfn1 and Mfn2 may be responsible for abnormal mitochondrial dynamics that we found in the cortex of HD patients, and may contribute to neuronal damage in HD patients. The presence of mutant Htt oligomers in the nucleus of HD neurons and in mitochondria may disrupt neuronal functions. Based on these findings, we propose that mutant Htt in association with mitochondria imbalance and mitochondrial dynamics impairs axonal transport of mitochondria, decreases mitochondrial function and damages neurons in affected brain regions of HD patients.

Human papillomavirus infection and its possible correlation with p63 expression in cervical cancer in Japan, Mongolia, and Myanmar.

Although human papillomavirus (HPV) 16 is the cause of cervical cancer in most countries including Japan, the involvement of cervical cancer with HPV types in Mongolian and Myanmar populations is largely unknown. We examined the expression of HPV in formalin-fixed and paraffin-embedded cervical tissues from 40 Japanese, 32 Mongolian, and 30 Myanmar cervical cancer patients. We performed immunohistochemistry using anti-HPV16 and anti-HPV 1, 6, 11, 16, 18 and 31 cocktail and then correlated it with the expression of Ki-67 and p63. HPV 16 was detected in 72%, 65% and 50% of Japanese, Mongolian and Myanmar cervical cancer patients, respectively, whereas 5 (13%) of the 40 patients, 8 (25%) of the 32 patients and 7 (23%) of the 30 patients in HPV 16-negative cancers were positive for other HPV types included in the cocktail, respectively. Ki-67 labeling index (LI) as well as p63 LI was significantly higher in HPV 16-positive patients than in HPV 16-negative ones in the Japanese and Mongolian samples. p63 expression was significantly associated with stage III and IV in Japan and Mongolia. These findings suggest that HPV 16 may be associated with cell proliferative activity and tumor progression, possibly depending upon the expression of p63 in the cervical cancer. In addition, immunohistochemical detection for distinguishing the type of HPV may also be useful for cervical cancer in the clinical setting.

Toxicity of neurons treated with herbicides and neuroprotection by mitochondria-targeted antioxidant SS31.

The purpose of this study was to determine the neurotoxicity of two commonly used herbicides: picloram and triclopyr and the neuroprotective effects of the mitochondria-targeted antioxidant, SS31. Using mouse neuroblastoma (N2a) cells and primary neurons from C57BL/6 mice, we investigated the toxicity of these herbicides, and protective effects of SS1 peptide against picloram and triclopyr toxicity. We measured total RNA content, cell viability and mRNA expression of peroxiredoxins, neuroprotective genes, mitochondrial-encoded electron transport chain (ETC) genes in N2a cells treated with herbicides and SS31. Using primary neurons from C57BL/6 mice, neuronal survival was studied in neurons treated with herbicides, in neurons pretreated with SS31 plus treated with herbicides, neurons treated with SS31 alone, and untreated neurons. Significantly decreased total RNA content, and cell viability in N2a cells treated with picloram and triclopyr were found compared to untreated N2a cells. Decreased mRNA expression of neuroprotective genes, and ETC genes in cells treated with herbicides was found compared to untreated cells. Decreased mRNA expression of peroxiredoxins 1-6 in N2a cells treated with picloram was found, suggesting that picloram affects the antioxidant enzymes in N2a cells. Immunofluorescence analysis of primary neurons revealed that decreased neuronal branching and degenerating neurons in neurons treated with picloram and triclopyr. However, neurons pretreated with SS31 prevented degenerative process caused by herbicides. Based on these results, we propose that herbicides--picloram and triclopyr appear to damage neurons, and the SS31 peptide appears to protect neurons from herbicide toxicity.

Dynamin-related protein 1 and mitochondrial fragmentation in neurodegenerative diseases.

The purpose of this article is to review the recent developments of abnormal mitochondrial dynamics, mitochondrial fragmentation, and neuronal damage in neurodegenerative diseases, including Alzheimer's, Parkinson's, Huntington's, and amyotrophic lateral sclerosis. The GTPase family of proteins, including fission proteins, dynamin related protein 1 (Drp1), mitochondrial fission 1 (Fis1), and fusion proteins (Mfn1, Mfn2 and Opa1) are essential to maintain mitochondrial fission and fusion balance, and to provide necessary adenosine triphosphate to neurons. Among these, Drp1 is involved in several important aspects of mitochondria, including shape, size, distribution, remodeling, and maintenance of mitochondria in mammalian cells. In addition, recent advancements in molecular, cellular, electron microscopy, and confocal imaging studies revealed that Drp1 is associated with several cellular functions, including mitochondrial and peroxisomal fragmentation, phosphorylation, SUMOylation, ubiquitination, and cell death. In the last two decades, tremendous progress has been made in researching mitochondrial dynamics, in yeast, worms, and mammalian cells; and this research has provided evidence linking Drp1 to neurodegenerative diseases. Researchers in the neurodegenerative disease field are beginning to recognize the possible involvement of Drp1 in causing mitochondrial fragmentation and abnormal mitochondrial dynamics in neurodegenerative diseases. This article summarizes research findings relating Drp1 to mitochondrial fission and fusion, in yeast, worms, and mammals. Based on findings from the Reddy laboratory and others', we propose that mutant proteins of neurodegenerative diseases, including AD, PD, HD, and ALS, interact with Drp1, activate mitochondrial fission machinery, fragment mitochondria excessively, and impair mitochondrial transport and mitochondrial dynamics, ultimately causing mitochondrial dysfunction and neuronal damage.

Amyloid-beta and mitochondria in aging and Alzheimer's disease: implications for synaptic damage and cognitive decline.

This article reviews the role of amyloid-beta (Abeta) and mitochondria in synaptic damage and cognitive decline found in patients with Alzheimer's disease (AD). Recent molecular, cellular, animal model, and postmortem brain studies have revealed that Abeta and mitochondrial abnormalities are key factors that cause synaptic damage and cognitive decline in AD. Abeta is reported to accumulate in subcellular compartments and to impair the normal function of neurons in AD patients. Further, recent studies using biochemical methods and electron microscopy have revealed that the accumulation of Abeta at nerve terminals affect synaptic activities, including the release of neurotransmitters and synaptic vesicles. Recent studies of the relationship between mitochondria and Abeta in AD patients suggest that in mitochondria, structural changes caused by Abeta result in increased mitochondrial fragmentation, decreased mitochondrial fusion, mitochondrial dysfunction, and synaptic damage. This paper discusses the latest research on Abeta, mitochondria, age-dependent factors of AD in the brain, and synaptic damage in AD. This paper also briefly discusses potential mitochondrial therapeutics in the treatment of patients with AD.