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A correction to the article "Sodium Phenylbutyrate Prolongs Survival and Regulates Expression of Anti-Apoptotic Genes in Transgenic Amyotrophic Lateral Sclerosis Mice" that was published in the previous issue is presented.

Presents a correction to the article "Increased Survival and Neuroprotective Effects of BN82451 in a Transgenic Mouse Model of Huntington's Disease," published in the 2003 issue of the "Journal of Neurochemistry," vol. 86.

Huntington's disease (HD) is an autosomal dominant inherited neurodegenerative disorder characterized by progressive motor dysfunction, emotional disturbances, dementia, and weight loss. It is caused by an expanded trinucleotide CAG repeat in the gene coding for the protein, huntingtin. Although no one specific interaction of mutant huntingtin has been suggested to be the pathologic trigger, a large body of evidence suggests that, in both the human condition and in HD mice, oxidative stress may play a role in the pathogenesis of HD. Increased levels of oxidative damage products, including protein nitration, lipid peroxidation, DNA oxidation, and exacerbated lipofuscin accumulation, occur in HD. Strong evidence exists for early oxidative stress in HD, coupled with mitochondrial dysfunction, each exacerbating the other and leading to an energy deficit. If oxidative damage plays a role in HD, then therapeutic strategies that reduce reactive oxygen species may ameliorate the neurodegenerative process. Two such strategies, using coenzyme Q10 and creatine, have been proposed. Although each agent has had limited efficacy in HD patients, the optimal therapeutic dose may have been underestimated. High-dose coenzyme Q10 and creatine are safe and tolerable in HD patients and are currently under investigation. In addition, there are parallels in reducing markers of oxidative stress in both HD mice and HD patients after treatment. It is likely that high-dose coenzyme Q10, creatine, or both agents, will represent a cornerstone defense in ameliorating the progression of HD. [ABSTRACT FROM AUTHOR]

Abstract: 3-Nitropropionic acid (3-NP), an irreversible inhibitor of succinate dehydrogenase, produces selective lesions in striatal neurons that resemble those observed in Huntington''s disease neuropathology. In this study, we evaluated the role of peripheral bone marrow-derived cells (BMDCs) in the 3-NP-induced striatal damage by transplanting bone marrow cells with human SOD1 G93A mutation (mSOD1G93A) which induces amyotrophic lateral sclerosis through an unknown gain of toxicity and mitochondrial dysfunction. We assessed striatal damage after 3-NP treatment in the recipient C57BL/6 wild-type (WT) mice that received bone marrow cells from WT or mSOD1G93A transgenic donor mice (WT→WT or mSODG93A →WT). After intraperitoneal injection of 3-NP, six of the eight mSOD1G93A →WT mice had bilateral striatal lesions while only one out of eight WT→WT mice had a striatal lesion. The lesion volume was significantly higher in the mSOD1G93A →WT mice than in the WT→WT mice. However, following an intrastriatal injection of 3-NP, there was no significant difference in the lesion volumes between the WT→WT mice and mSOD1G93A →WT mice. Thus, the exacerbation of 3-NP-induced striatal damage in mSODG93A →WT mice was only seen after systemic administration of 3-NP, but not after intrastriatal injection. These results demonstrate that altered SOD1 activity (mSODG93A) in BMDCs affects striatal damage probably through a mechanism involving a systemic factor. [Copyright &y& Elsevier]

Mitochondrial dysfunction is associated with neuronal loss in Huntington's disease (HD), a neurodegenerative disease caused by an abnormal polyglutamine expansion in huntingtin (Htt). However, the mechanisms linking mutant Htt and mitochondrial dysfunction in HD remain unknown. We identify an interaction between mutant Htt and the TIM23 mitochondrial protein import complex. Remarkably, recombinant mutant Htt directly inhibited mitochondrial protein import in vitro. Furthermore, mitochondria from brain synaptosomes of presymptomatic HD model mice and from mutant Htt-expressing primary neurons exhibited a protein import defect, suggesting that deficient protein import is an early event in HD. The mutant Htt-induced mitochondrial import defect and subsequent neuronal death were attenuated by overexpression of TIM23 complex subunits, demonstrating that deficient mitochondrial protein import causes mutant Htt-induced neuronal death. Collectively, these findings provide evidence for a direct link between mutant Htt, mitochondrial dysfunction and neuronal pathology, with implications for mitochondrial protein import-based therapies in HD. [ABSTRACT FROM AUTHOR]

Abstract: Caspase-mediated cell death contributes to the pathogenesis of motor neuron degeneration in the mutant SOD1G93A transgenic mouse model of amyotrophic lateral sclerosis (ALS), along with other factors such as inflammation and oxidative damage. By screening a drug library, we found that melatonin, a pineal hormone, inhibited cytochrome c release in purified mitochondria and prevented cell death in cultured neurons. In this study, we evaluated whether melatonin would slow disease progression in SOD1G93A mice. We demonstrate that melatonin significantly delayed disease onset, neurological deterioration and mortality in ALS mice. ALS-associated ventral horn atrophy and motor neuron death were also inhibited by melatonin treatment. Melatonin inhibited Rip2/caspase-1 pathway activation, blocked the release of mitochondrial cytochrome c, and reduced the overexpression and activation of caspase-3. Moreover, for the first time, we determined that disease progression was associated with the loss of both melatonin and the melatonin receptor 1A (MT1) in the spinal cord of ALS mice. These results demonstrate that melatonin is neuroprotective in transgenic ALS mice, and this protective effect is mediated through its effects on the caspase-mediated cell death pathway. Furthermore, our data suggest that melatonin and MT1 receptor loss may play a role in the pathological phenotype observed in ALS. The above observations indicate that melatonin and modulation of Rip2/caspase-1/cytochrome c or MT1 pathways may be promising therapeutic approaches for ALS. [Copyright &y& Elsevier]

The US National Institute of Neurological Disorders and Stroke convened major stakeholders in June 2012 to discuss how to improve the methodological reporting of animal studies in grant applications and publications. The main workshop recommendation is that at a minimum studies should report on sample-size estimation, whether and how animals were randomized, whether investigators were blind to the treatment, and the handling of data. We recognize that achieving a meaningful improvement in the quality of reporting will require a concerted effort by investigators, reviewers, funding agencies and journal editors. Requiring better reporting of animal studies will raise awareness of the importance of rigorous study design to accelerate scientific progress. [ABSTRACT FROM AUTHOR]

Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the progressive loss of motor neurons. Currently, there is only one FDA-approved treatment for ALS (riluzole), and that drug only extends life, on average, by 2–3months. Mutations in Cu/Zn superoxide dismutase (SOD1) are found in familial forms of the disease and have played an important role in the study of ALS pathophysiology. On the basis of their activity in a PC12-G93A-YFP high-throughput screening assay, several bioactive compounds have been identified and classified as cyclohexane-1,3-dione (CHD) derivatives. A concise and efficient synthetic route has been developed to provide diverse CHD analogs. The structural modification of the CHD scaffold led to the discovery of a more potent analog (26) with an EC50 of 700nM having good pharmacokinetic properties, such as high solubility, low human and mouse metabolic potential, and relatively good plasma stability. It was also found to efficiently penetrate the blood–brain barrier. However, compound 26 did not exhibit any significant life span extension in the ALS mouse model. It was found that, although 26 was active in PC12 cells, it had poor activity in other cell types, including primary cortical neurons, indicating that it can penetrate into the brain, but is not active in neuronal cells, potentially due to poor selective cell penetration. Further structural modification of the CHD scaffold was aimed at improving global cell activity as well as maintaining potency. Two new analogs (71 and 73) were synthesized, which had significantly enhanced cortical neuronal cell permeability, as well as similar potency to that of 26 in the PC12-G93A assay. These CHD analogs are being investigated further as novel therapeutic candidates for ALS. [Copyright &y& Elsevier]

Huntington disease (HD) is a devastating autosomal-dominant neurodegenerative disorder. It is caused by expansion of a CAG repeat in the first exon of the huntingtin (HTT) gene that encodes a mutant HTT protein with a polyglutamine (polyQ) expansion at the amino terminus. Here, we demonstrate that WT HTT regulates ciliogenesis by interacting through huntingtin-associated protein 1 (HAP1) with pericentriolar material 1 protein (PCM1). Loss of Htt in mouse cells impaired the retrograde trafficking of PCM1 and thereby reduced primary cilia formation. In mice, deletion of Htt in ependymal cells led to PCM1 mislocalization, alteration of the cilia layer, and hydrocephalus. Pathogenic polyQ expansion led to centrosomal accumulation of PCM1 and abnormally long primary cilia in mouse striatal cells. PCM1 accumulation in ependymal cells was associated with longer cilia and disorganized cilia layers in a mouse model of HD and in HD patients. Longer cilia resulted in alteration of the cerebrospinal fluid flow. Thus, our data indicate that WT HTT is essential for protein trafficking to the centrosome and normal ciliogenesis. In HD, hypermorphic ciliogenesis may affect signaling and neuroblast migration so as to dysregulate brain homeostasis and exacerbate disease progression. [ABSTRACT FROM AUTHOR]

Abstract: Amyotrophic lateral sclerosis (ALS) is an orphan neurodegenerative disease currently without a cure. Mutations in copper/zinc superoxide dismutase 1 (SOD1) have been implicated in the pathophysiology of this disease. Using a high-throughput screening assay expressing mutant G93A SOD1, two bioactive chemical hit compounds (1 and 2), identified as arylsulfanyl pyrazolones, were identified. The structural optimization of this scaffold led to the generation of a more potent analogue (19) with an EC50 of 170nM. To determine the suitability of this class of compounds for further optimization, 1 was subjected to a battery of pharmacokinetic assays; most of the properties of 1 were good for a screening hit, except it had a relatively rapid clearance and short microsomal half-life stability. Compound 2 was found to be blood–brain barrier penetrating with a brain/plasma ratio=0.19. The optimization of this class of compounds could produce novel therapeutic candidates for ALS patients. [ABSTRACT FROM AUTHOR]

Abstract: A major goal of current clinical research in Huntington''s disease (HD) has been to identify preclinical and manifest disease biomarkers, as these may improve both diagnosis and the power for therapeutic trials. Although the underlying biochemical alterations and the mechanisms of neuronal degeneration remain unknown, energy metabolism defects in HD have been chronicled for many years. We report that the brain isoenzyme of creatine kinase (CK-BB), an enzyme important in buffering energy stores, was significantly reduced in presymptomatic and manifest disease in brain and blood buffy coat specimens in HD mice and HD patients. Brain CK-BB levels were significantly reduced in R6/2 mice by ∼18% to ∼68% from 21 to 91days of age, while blood CK-BB levels were decreased by ∼14% to ∼44% during the same disease duration. Similar findings in CK-BB levels were observed in the 140 CAG mice from 4 to 12months of age, but not at the earliest time point, 2months of age. Consistent with the HD mice, there was a grade-dependent loss of brain CK-BB that worsened with disease severity in HD patients from ∼28% to ∼63%, as compared to non-diseased control patients. In addition, CK-BB blood buffy coat levels were significantly reduced in both premanifest and symptomatic HD patients by ∼23% and ∼39%, respectively. The correlation of CK-BB as a disease biomarker in both CNS and peripheral tissues from HD mice and HD patients may provide a powerful means to assess disease progression and to predict the potential magnitude of therapeutic benefit in this disorder. [Copyright &y& Elsevier]

Accumulation of expanded polyglutamine proteins is considered to be a major pathogenic biomarker of Huntington disease. We isolated SCAMP5 as a novel regulator of cellular accumulation of expanded polyglutamine track protein using cell-based aggregation assays. Ectopic expression of SCAMP5 augments the formation of ubiquitin-positive and detergent-resistant aggregates of mutant huntingtin (mtHTT). Expression of SCAMP5 is markedly increased in the striatum of Huntington disease patients and is induced in cultured striatal neurons by endoplasmic reticulum (ER) stress or by mtHTT. The increase of SCAMP5 impairs endocytosis, which in turn enhances mtHTT aggregation. On the contrary, down-regulation of SCAMP5 alleviates ER stress-induced mtHTT aggregation and endocytosis inhibition. Moreover, stereotactic injection into the striatum and intraperitoneal injection of tunicamycin significantly increase mtHTT aggregation in the striatum of R6/2 mice and in the cortex of N17182Q mice, respectively. Taken together, these results suggest that exposure to ER stress increases SCAMP5 in the striatum, which positively regulates mtHTT aggregation via the endocytosis pathway. [ABSTRACT FROM AUTHOR]

Abstract: Parkinson''s disease (PD) is a progressive neurodegenerative disorder for which there is no current therapy preventing cumulative neuronal loss. There is substantial evidence that mitochondrial dysfunction, oxidative stress, and associated caspase activity underlie the neurodegeneration observed. One potential drug therapy is the potent free radical scavenger and antioxidant cystamine, which has demonstrated significant clinical potential in models of neurodegenerative disorders and human neurological disease. This study examined the oral efficacy of cystamine in the MPTP and 6-hydroxydopamine neurotoxin models of PD. The neuroprotective effects of cystamine treatment significantly ameliorated nigral neuronal loss, preserved striatal dopaminergic projections, and improved striatal dopamine and metabolite levels, as compared to MPTP alone. Cystamine normalized striatal 8-hydroxy-2′-deoxyguanosine levels and ATP concentrations, consistent with reduced oxidative stress and improved mitochondrial function. Cystamine also protected against MPTP-induced mitochondrial loss, as identified by mitochondrial heat shock protein 70 and superoxide dismutase 2, with concomitant reductions in cytochrome c and caspase-3 activities. The neuroprotective value of cystamine was confirmed in the 6-hydroxydopamine model. Together these findings show cystamine''s therapeutic benefit to reduce neuronal loss through attenuation of oxidative stress and mitochondrial dysfunction, providing the rationale for human clinical trials in PD patients. [Copyright &y& Elsevier]

This study was to characterize the neuroprotective effects of nortriptyline, a tricyclic antidepressant, in mouse models of chronic neurodegeneration [amyotrophic lateral sclerosis (ALS) and Huntington's disease (HD)]. Nortriptyline was originally selected from a library screening of 1040 FDA-approved drugs by using isolated mitochondria. It emerged as a strong inhibitor of mitochondrial permeability transition (mPT). Our results showed that nortriptyline significantly delayed disease onset and extended the lifespan of ALS mice although its effect on mortality was less than that on onset. We also tested promethazine, another compound which emerged from the same screening, in ALS mice. Promethazine-treated ALS mice exhibited a significant delay in disease onset but not in mortality. Histochemistry analysis found that nortriptyline treatment indeed protected motor neurons from death and reduced ventral horn atrophy in ALS mice. Furthermore, release of cytochrome c and activation of caspase 3, two molecular phenomena associated with mitochondrial-pathway-mediated cell death, were inhibited by nortriptyline. We also demonstrated similar beneficial effects of nortriptyline in HD mice: it extended the presymptomatic portion of the disease but had no effect on mortality. In an established cellular model of HD, nortriptyline inhibited cell death and decreased loss of mitochondrial membrane potential. In summary, this study indicated the potential therapeutic usefulness of nortriptyline in ALS and HD. In addition, our data suggested a role for mPT in chronic neurodegeneration, particularly at the early rather than the advanced disease stages. [ABSTRACT FROM AUTHOR]

Immunotherapy against the amyloid-β (Aβ) peptide is a valuable potential treatment for Alzheimer disease (AD). An ideal antigen should be soluble and nontoxic, avoid the C-terminally located T-cell epitope of Aβ, and yet be capable of eliciting antibodies that recognize Aβ fibrils and neurotoxic Aβ oligomers but not the physiological monomeric species of Aβ. We have described here the construction and immunological characterization of a recombinant antigen with these features obtained by tandem multimerization of the immunodominant B-cell epitope peptide Aβ1-15 (Aβ15) within the active site loop of bacterial thioredoxin (Trx). Chimeric Trx(Aβ15)n polypeptides bearing one, four, or eight copies of Aβ15 were constructed and injected into mice in combination with alum, an adjuvant approved for human use. All three polypeptides were found to be immunogenic, yet eliciting antibodies with distinct recognition specificities. The anti-Trx(Aβ15)4 antibody, in particular, recognized Aβ42 fibrils and oligomers but not monomers and exhibited the same kind of conformational selectivity against transthyretin, an amyloidogenic protein unrelated in sequence to Aβ. We have also demonstrated that anti-Trx(Aβ15)4, which binds to human AD plaques, markedly reduces Aβ pathology in transgenic AD mice. The data indicate that a conformational epitope shared by oligomers and fibrils can be mimicked by a thioredoxin-constrained Aβ fragment repeat and identify Trx(Aβ15)4 as a promising new tool for AD immunotherapy. [ABSTRACT FROM AUTHOR]

Chromatin remodeling and transcription regulation are tightly controlled under physiological conditions. It has been suggested that altered chromatin modulation and transcription dysfunction may play a role in the pathogenesis of Huntington's disease (HD). Increased histone methylation, a well established mechanism of gene silencing, results in transcriptional repression. ERG-associated protein with SET domain (ESET). a histone H3 (K9) methyltransferase. mediates histone methylation. We show that ESET expression is markedly increased in HO patients and in transgenic R6/2 HD mice. Similarly, the protein level of trimethylated histone H3 (K9) was also elevated in HD patients and in R6/2 mice. We further demonstrate that both specificity protein 1 (Spi) and specificity protein 3 (Sp3) act as transcriptional activators of the ESET promoter in neurons and that mithramycin, a clinically approved guanosine-cytosine-rich DNA binding antitumor antibiotic, interferes with the DNA binding of these Sp family transcription factors, suppressing basal ESET promoter activity in a dose dependent manner. The combined pharmacological treatment with mithramycin and cystamine down-regulates ESET gene expression and reduces hypertrimethylation of histone H3 (Kg). This polytherapy significantly ameliorated the behavioral and neuropathological phenotype in the R6/2 mice and extended survival over 40%, well beyond any existing reported treatment in HD mice. Our data suggest that modulation of gene silencing mechanisms, through regulation of the ESET gene is important to neuronal survival and, as such, may be a promising treatment in HO patients. [ABSTRACT FROM AUTHOR]

Interactions between mutant huntingtin (Htt) and a variety of transcription factors including specificity proteins (Sp) have been suggested as a central mechanism in Huntington disease (HD). However, the transcriptional activity induced by Htt in neurons that triggers neuronal death has yet to be fully elucidated. In the current study, we characterized the relationship of Sp1 to Htt protein aggregation and neuronal cell death. We found increased levels of Sp1 in neuronal-like PC12 cells expressing mutant Htt, primary striatal neurons, and brain tissue of HD transgenic mice. Sp1 levels were also elevated when 3-nitropropionate (3-NP) was used to induce cell death in PC12 cells. To assess the effects of knocking down Sp1 in HD pathology, we used Sp1 siRNA, a heterozygous Sp1 knock-out mouse, and mithramycin A, a DNA-intercalating agent that inhibits Sp1 function. The three approaches consistently yielded reduced levels of Sp1 which ameliorated toxicity caused by either mutant Htt or 3-NP. In addition, when HD mice were crossed with Sp1 heterozygous knock-out mice, the resulting offspring did not experience the loss of dopamine D2 receptor mRNA characteristic of HD mice, and survived longer than their HD counterparts. Our data suggest that enhancement of transcription factor Sp1 contributes to the pathology of HD and demonstrates that its suppression is beneficial. [ABSTRACT FROM AUTHOR]

Abstract: There is substantial evidence that a bioenergetic defect may play a role in the pathogenesis of Huntington''s Disease (HD). A potential therapy for remediating defective energy metabolism is the mitochondrial cofactor, coenzyme Q10 (CoQ10). We have reported that CoQ10 is neuroprotective in the R6/2 transgenic mouse model of HD. Based upon the encouraging results of the CARE-HD trial and recent evidence that high-dose CoQ10 slows the progressive functional decline in Parkinson''s disease, we performed a dose ranging study administering high levels of CoQ10 from two commercial sources in R6/2 mice to determine enhanced efficacy. High dose CoQ10 significantly extended survival in R6/2 mice, the degree of which was dose- and source-dependent. CoQ10 resulted in a marked improvement in motor performance and grip strength, with a reduction in weight loss, brain atrophy, and huntingtin inclusions in treated R6/2 mice. Brain levels of CoQ10 and CoQ9 were significantly lower in R6/2 mice, in comparison to wild type littermate control mice. Oral administration of CoQ10 elevated CoQ10 plasma levels and significantly increased brain levels of CoQ9, CoQ10, and ATP in R6/2 mice, while reducing 8-hydroxy-2-deoxyguanosine concentrations, a marker of oxidative damage. We demonstrate that high-dose administration of CoQ10 exerts a greater therapeutic benefit in a dose dependent manner in R6/2 mice than previously reported and suggest that clinical trials using high dose CoQ10 in HD patients are warranted. [Copyright &y& Elsevier]

Abstract: Abnormalities in the function of α-synuclein are implicated in the pathogenesis of Parkinson''s disease (PD). We found that α-synuclein-deficient mice are resistant to MPTP-induced degeneration of dopaminergic neurons. There was dose-dependent protection against loss of both dopamine in the striatum and dopamine transporter (DAT) immunoreactive neurons in the substantia nigra. These effects were not due to alterations in MPTP processing. We found that α-synuclein-deficient mice are also resistant to both malonate and 3-nitropropionic acid (3-NP) neurotoxicity. There was reduced generation of reactive oxygen species in α-synuclein-deficient mice following administration of 3-NP. These findings implicate α-synuclein as a modulator of oxidative damage, which has been implicated in neuronal death produced by MPTP and other mitochondrial toxins. [Copyright &y& Elsevier]

Abstract: Huntington''s disease (HD) is a fatal neurodegenerative disorder of genetic origin with no known therapeutic intervention that can slow or halt disease progression. Transgenic murine models of HD have significantly improved the ability to assess potential therapeutic strategies. The R6/2 murine model of HD, which recapitulates many aspects of human HD, has been used extensively in pre-clinical HD therapeutic treatment trials. Of several potential therapeutic candidates, both minocycline and coenzyme Q10 (CoQ10) have been demonstrated to provide significant improvement in the R6/2 mouse. Given the specific cellular targets of each compound, and the broad array of abnormalities thought to underlie HD, we sought to assess the effects of combined minocycline and CoQ10 treatment in the R6/2 mouse. Combined minocycline and CoQ10 therapy provided an enhanced beneficial effect, ameliorating behavioral and neuropathological alterations in the R6/2 mouse. Minocycline and CoQ10 treatment significantly extended survival and improved rotarod performance to a greater degree than either minocycline or CoQ10 alone. In addition, combined minocycline and CoQ10 treatment attenuated gross brain atrophy, striatal neuron atrophy, and huntingtin aggregation in the R6/2 mice relative to individual treatment. These data suggest that combined minocycline and CoQ10 treatment may offer therapeutic benefit to patients suffering from HD. [Copyright &y& Elsevier]

Cyclic AMP response element-binding protein (CREB) is a widely expressed transcription factor whose role in neuronal protection is now well established. Here we report that CREB is present in the mitochondrial matrix of neurons and that it binds directly to cyclic AMP response elements (CREs) found within the mitochondrial genome. Disruption of CREB activity in the mitochondria decreases the expression of a subset of mitochondrial genes, including the ND5 subunit of complex I, down-regulates complex I-dependent mitochondrial respiration, and increases susceptibility to 3-nitropropionic acid, a mitochondrial toxin that induces a clinical and pathological phenotype similar to Huntington disease. These results demonstrate that regulation of mitochondrial gene expression by mitochondrial CREB, in part, underlies the protective effects of CREB and raise the possibility that decreased mitochondrial CREB activity contributes to the mitochondrial dysfunction and neuronal loss associated with neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

Abstract: Huntington''s disease (HD) is an autosomal dominant and fatal neurological disorder characterized by a clinical triad of progressive choreiform movements, psychiatric symptoms, and cognitive decline. HD is caused by an expanded trinucleotide CAG repeat in the gene coding for the protein huntingtin. No proven treatment to prevent the onset or to delay the progression of HD currently exists. While a direct causative pathway from the gene mutation to the selective neostriatal neurodegeneration remains unclear, it has been hypothesized that interactions of the mutant huntingtin protein or its fragments may result in a number of interrelated pathogenic mechanisms triggering a cascade of molecular events that lead to the untimely neuronal death observed in HD. One putative pathological mechanism reported to play a prominent role in the pathogenesis of HD is mitochondrial dysfunction and the subsequent reduction of cellular energy. Indeed, if mitochondrial impairment and reduced energy stores play roles in the neuronal loss in HD, then a therapeutic strategy that buffers intracellular energy levels may ameliorate the neurodegenerative process. Sustained ATP levels may have both direct and indirect importance in ameliorating the severity of many of the pathogenic mechanisms associated with HD. Creatine, a guanidino compound produced endogenously and acquired exogenously through diet, is a critical component in maintaining much needed cellular energy. As such, creatine is one of a number of ergogens that may provide a relatively safe and immediately available therapeutic strategy to HD patients that may be the cornerstone of a combined treatment necessary to delay the relentless progression of HD. [Copyright &y& Elsevier]

Huntington's disease is a neurodegenerative illness caused by expansion of CAG repeats at the N-terminal end of the protein huntingtin. We examined longitudinal changes in brain metabolite levels using in vivo magnetic resonance spectroscopy in five different mouse models. There was a large (>50%) exponential decrease in N-acetyl aspartate (NAA) with time in both striatum and cortex in mice with 150 CAG repeats (R6/2 strain). There was a linear decrease restricted to striatum in N171-82Q mice with 82 CAG repeats. Both the exponential and linear decreases of NAA were paralleled in time by decreases in neuronal area measured histologically. Yeast artificial chromosome transgenic mice with 72 CAG repeats, but low expression levels, had less striatal NAA loss than the N171–82Q mice (15% vs. 43%). We evaluated the effect of gene context in mice with an approximate 146 CAG repeat on the hypoxanthine phosphoribosyltransferase gene (HPRT). HPRT mice developed an obese phenotype in contrast to weight loss in the R6/2 and N171–82Q mice. These mice showed a small striatal NAA loss (21%), and a possible increase in brain lipids detectable by magnetic resonance (MR) spectroscopy and decreased brain water T1. Our results indicate profound metabolic defects that are strongly affected by CAG repeat length, as well as gene expression levels and protein context. [ABSTRACT FROM AUTHOR]

The protein kinase A (PKA) and the cAMP response element (CRE) binding protein (CREB) signaling pathways mediate plasticity and prosurvival responses in neurons through their ability to regulate gene expression. The PKA-CREB signaling mechanism has been well characterized in terms of nuclear gene expression. We show that the PKA catalytic and regulatory subunits and CREB are localized to the mitochondrial matrix of neurons. Mitochondrial CRE sites were identified by using both serial analyses of chromatin occupancy and chromatin immunoprecipitation. Deferoxamine (DFO), an antioxidant and iron chelator known to inhibit oxidative stress-induced death, activated mitochondrial PKA and increased mitochondrial CREB phosphorylation (Ser-133). DFO increased CREB binding to CRE in the mitochondrial D-loop DNA and D-loop CRE-driven luciferase activity. In contrast, KT5720, a specific inhibitor of PKA, reduced DFO-mediated neuronal survival against oxidative stress induced by glutathione depletion. Neuronal survival by DFO may be, in part, mediated by the mitochondrial PKA-dependent pathway. These results suggest that the regulation of mitochondrial function via the mitochondrial PKA and CREB pathways may underlie some of the salutary effects of DFO in neurons. [ABSTRACT FROM AUTHOR]

Abstract: We demonstrate that the histone deacetylase (HDAC) inhibitor drug trichostatin A (TSA) reduces spinal cord inflammation, demyelination, neuronal and axonal loss and ameliorates disability in the relapsing phase of experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis (MS). TSA up-regulates antioxidant, anti-excitotoxicity and pro-neuronal growth and differentiation mRNAs. TSA also inhibits caspase activation and down-regulates gene targets of the pro-apoptotic E2F transcription factor pathway. In splenocytes, TSA reduces chemotactic, pro-Th1 and pro-proliferative mRNAs. A transcriptional imbalance in MS may contribute to immune dysregulation and neurodegeneration, and we identify HDAC inhibition as a transcriptional intervention to ameliorate this imbalance. [Copyright &y& Elsevier]

Multiple molecular defects trigger cell death in amyotrophic lateral sclerosis (ALS). Among these, altered transcriptional activity may perturb many cellular functions, leading to a cascade of secondary pathological effects. We showed that pharmacological treatment, using the histone deacetylase inhibitor sodium phenylbutyrate, significantly extended survival and improved both the clinical and neuropathological phenotypes in G93A transgenic ALS mice. Phenylbutyrate administration ameliorated histone hypoacetylation observed in G93A mice and induced expression of nuclear factor-κB (NF-κB) p50, the phosphorylated inhibitory subunit of NF-κB (pIκB) and beta cell lymphoma 2 (bcl-2), but reduced cytochromecand caspase expression. Curcumin, an NF-κB inhibitor, and mutation of the NF-κB responsive element in the bcl-2 promoter, blocked butyrate-induced bcl-2 promoter activity.We provide evidence that the pharmacological induction of NF-κB-dependent transcription andbcl-2gene expression is neuroprotective in ALS mice by inhibiting programmed cell death. Phenylbutyrate acts to phosphorylate IκB, translocating NF-κB p50 to the nucleus, or to directly acetylate NF-κB p50. NF-κB p50 transactivatesbcl-2gene expression. Up-regulated bcl-2 blocks cytochromecrelease and subsequent caspase activation, slowing motor neuron death. These transcriptional and post-translational pathways ultimately promote motor neuron survival and ameliorate disease progression in ALS mice. Phenylbutyrate may therefore provide a novel therapeutic approach for the treatment of patients with ALS. [ABSTRACT FROM AUTHOR]

Huntington's disease (HD) is caused by an expansion of exonic CAG triplet repeats in the gene encoding the huntingtin protein (Htt), however, the means by which neurodegeneration occurs remains obscure. There is evidence that mutant Htt interacts with transcription factors leading to reduced histone acetylation. We report that administration of the histone deacetylase inhibitor phenylbutyrate after onset of symptoms in a transgenic mouse model of HD significantly extends survival and attenuates both gross brain and neuronal atrophy. Administration of phenylbutyrate increased brain histone acetylation and decreased histone methylation levels as assessed by both immunocytochemistry and Western blots. Phenylbutyrate increased mRNA for components of the ubiquitin-proteosomal pathway and down-regulated caspases implicated in apoptotic cell death, and active caspase 3 immunoreactivity in the striatum. These results show that administration of phenylbutyrate, at doses that are well tolerated in man, exerts significant neuroprotective effects in a transgenic mouse model of HD, and therefore represents a very promising therapeutic approach for HD. [ABSTRACT FROM AUTHOR]

Inflammatory mechanisms have been implicated in the pathogenesis of Huntington''s disease (HD). Possible benefits of anti-inflammatory treatments include improved folding of mutant huntingtin mediated through chaperones, reduction of destructive cellular and humoral inflammatory pathways, and reduction of proapoptotic signaling mediated by NF-κB or other transcription factors. This study was performed to investigate the therapeutic potential of anti-inflammatory drugs as treatments for Huntington''s disease by examining whether two compounds in widespread human use can ameliorate the phenotype of HD transgenic mouse models. We examined the effectiveness of acetylsalicylate and rofecoxib as treatments for the R6/2 and N171-82Q transgenic mouse models of Huntington''s disease. Both drugs were administered from weaning. To monitor the effectiveness of the treatment, we analyzed the mice for weight loss, behavioral changes, and gross cerebral and striatal atrophy. The studies showed that neither drug benefited the animals at doses comparable to those tolerated by humans. [Copyright &y& Elsevier]

Caspases play an important role in neurodegeneration in Huntington's disease (HD). Members of the Bcl-2 family are critical modulators of terminal cell death pathways. However, alterations of Bcl-2 family members and their functional role in an in vivo model of HD have not been documented. With the goal of gaining mechanistic insight, we used a transgenic mouse model of HD (R6/2) to investigate the chronology of caspase activation and functional alterations in members of the Bcl-2 family. In R6/2 mice caspase activation precedes proapoptotic changes in Bcl-2 family members. Of the caspases that we screened, caspase-1-like activation was the first to be detected in the disease process (7 weeks). Proapoptotic changes in members of the Bcl-2 family were first detected at 9 weeks. To demonstrate a potential functional/therapeutic role of Bcl-2 in HD, we crossed R6/2 mice with mice overexpressing Bcl-2 in neurons. Transgenic expression of Bcl-2 in R6/2 mice resulted in slight prolonged survival. Understanding the chronology of apoptotic events provides important information for appropriate therapeutic targeting in this devastating and untreatable disease. [ABSTRACT FROM AUTHOR]

Huntington's disease (HD) is a neurodegenerative disease caused by polyglutamine (polyQ) expansion in the protein huntingtin (htt). Pathogenesis in HD seems to involve the formation of neuronal intranuclear inclusions and the abnormal regulation of transcription and signal transduction. To identify previously uncharacterized htt-interacting proteins in a simple model system, we used a yeast two-hybrid screen with a Caenorhabditis elegans activation domain library. We found a predicted SH3 domain protein (K08E3.3b) that interacts with N-terminal htt in two-hybrid tests. A human homolog of K08E3.3b is the Cdc42-interacting protein 4 (CIP4), a protein involved in Cdc42 and Wiskott-Aldrich syndrome protein-dependent signal transduction. CIP4 interacted in vitro with full-length htt from lymphoblastoid cells. Neuronal CIP4 immunoreactivity increased with neuropathological severity in the neostriatum of HD patients and partially colocalized to ubiquitin-positive aggregates. Marked CIP4 overexpression also was observed in Western blot from human HD brain striatum. The overexpression of CIP4 induced the death of striatal neurons. Our data suggest that CIP4 accumulation and cellular toxicity may have a role in HD pathogenesis. [ABSTRACT FROM AUTHOR]

In a transgenic mouse model of the neurodegenerative disorder Huntington''s disease (HD), age-dependent neurologic defects are accompanied by progressive alterations in glucose tolerance that culminate in the development of diabetes mellitus and insulin deficiency. Pancreatic islets from HD transgenic mice express reduced levels of the pancreatic islet hormones insulin, somatostatin, and glucagon and exhibit intrinsic defects in insulin production. Intranuclear inclusions accumulate with aging in transgenic pancreatic islets, concomitant with the decline in glucose tolerance. HD transgenic mice develop an age-dependent reduction of insulin mRNA expression and diminished expression of key regulators of insulin gene transcription, including the pancreatic homeoprotein PDX-1, E2A proteins, and the coactivators CBP and p300. Disrupted expression of a subset of transcription factors in pancreatic β cells by a polyglutamine expansion tract in the huntingtin protein selectively impairs insulin gene expression to result in insulin deficiency and diabetes. Selective dysregulation of gene expression in triplet repeat disorders provides a mechanism for pleiotropic cellular dysfunction that restricts the toxicity of ubiquitously expressed proteins to highly specialized subpopulations of cells. [Copyright &y& Elsevier]

Presents the biochemical, neuropathologic and genetic evidence for a role of the Gln-Ala repeat transcriptional activator CA150 in Huntington's disease pathogenesis. Interaction of Caenorhabditis elegans ZK1127.9 with htt in two-hybrid tests; In vitro interaction of CA150 with full-length htt from lymphoblastoid cells.

Huntington disease is an autosomal dominant neurodegenerative disease with no effective treatment. Minocycline is a tetracycline derivative with proven safety. After ischemia, minocycline inhibits caspase-1 and inducible nitric oxide synthetase upregulation, and reduces infarction. As caspase-1 and nitric oxide seem to play a role in Huntington disease, we evaluated the therapeutic efficacy of minocycline in the R6/2 mouse model of Huntington disease. We report that minocycline delays disease progression, inhibits caspase-1 and caspase-3 mRNA upregulation, and decreases inducible nitric oxide synthetase activity. In addition, effective pharmacotherapy in R6/2 mice requires caspase-1 and caspase-3 inhibition. This is the first demonstration of caspase-1 and caspase-3 transcriptional regulation in a Huntington disease model. [ABSTRACT FROM AUTHOR]

Mice transgenic for exon I of mutant huntingtin, with 141 CAG repeats, exhibit a profound symptomatology characterized by weight loss, motor disorders, and early death. We performed longitudinal analysis of metabolite levels in these mice using NMR spectroscopy in vivo and in vitro. These mice exhibited a large (53percent), nonlinear drop in in vivo N-acetyl aspartate (NAA) levels over time, commencing at approximately6 weeks of age, coincident with onset of symptoms. These drops in NAA levels occurred in the absence of neuronal death as measured by postmortem Nissl staining and neuronal counting but in the presence of nuclear inclusion bodies. In addition to decreased NAA, these mice showed a large elevation of glucose in the brain (600percent) consistent with a diabetic profile and elevations in blood glucose levels both before and after glucose loading. In vitro NMR analysis revealed significant increases in glutamine (100percent), taurine (95percent) cholines (200percent), and scyllo-inositol (333percent) and decreases in glutamate (24percent) and succinate (47percent). These results lead to two conclusions. NAA is reflective of the health of neurons and thus is a noninvasive marker, with a temporal progression similar to nuclear inclusion bodies and symptoms, of neuronal dysfunction in transgenic mice. Second, the presence of elevated glutamine is evidence of a profound metabolic defect. We present arguments that the elevated glutamine results from a decrease in neuronal-glial glutamate-glutamine cycling and a decrease in glutaminase activity. [ABSTRACT FROM AUTHOR]

Abstract: The polyglutamine-expanded N-terminal region of mutant huntingtin causes neurodegeneration in Huntington's disease (HD). Neuronal intranuclear and cytosolic inclusions composed of mutant huntingtin are found in brains of HD patients. Because tissue transglutaminase cross-links proteins into filamentous aggregates and polypeptide-bound glutamines are primary determining factors for tissue transglutaminase-catalyzed reactions, it has been hypothesized that tissue transglutaminase may contribute to the formation of these aggregates. In this report immunohistochemical and biochemical methods were used to demonstrate that tissue transglutaminase expression and transglutaminase activity are elevated in HD brains in a grade-dependent manner. In the striatum, tissue transglutaminase activity was significantly increased in the grade 3 HD cases compared with controls. When normalized to the neuronal marker calbindin D28k, immunoblot analysis revealed that in the striatum the levels of tissue transglutaminase were significantly increased in all HD cases compared with controls. Immunohistochemical staining of the HD striatum revealed that tissue transglutaminase immunoreactivity was markedly increased in all grades as compared with controls. In the superior frontal cortex, tissue transglutaminase activity was significantly higher in all HD cases as compared with controls. Quantitative analysis of immunoblots demonstrated that tissue transglutaminase levels were elevated in HD grades 2 and 3 cases. Tissue transglutaminase immunoreactivity within the superior frontal neocortex was also greater in all the HD cases compared with controls. These data clearly indicate that tissue transglutaminase is elevated in HD brain and may play a role in the disease process. Key Words: Huntington's disease--Tissue transglutaminase... [ABSTRACT FROM AUTHOR]