Itraconazole Confers Cytoprotection Against Neurodegenerative Disease-Associated Abnormal Protein Aggregation.

Cells perform regular maintenance to avoid the accumulation of misfolded proteins. Prolonged accumulation of these proteotoxic inclusions generates potential risk of ageing-related diseases such as neurodegenerative diseases. Therefore, removal of such abnormal aggregates can ensure the re-establishment of proteostasis. Ubiquitin proteasome system (UPS) actively participates in the selective removal of aberrantly folded clients with the help of complex proteasome machinery. However, specific induction of proteasome functions to remove abnormal proteins remains an open challenge. Here, we show that Itraconazole treatment induces proteasome activities and degrades the accumulation of bonafide-misfolded proteins, including heat-denatured luciferase. Exposure of Itraconazole elevates the degradation of neurodegenerative disease-associated proteins, e.g. expanded polyglutamine, mutant SOD1, and mutant α-synuclein. Our results suggest that Itraconazole treatment prevents the accumulation of neurodegenerative disease-linked misfolded proteins and generates cytoprotection. These findings reveal that Itraconazole removes abnormal proteins through sequential proteasomal activation and represents a potential protective therapeutic role against protein-misfolding neurodegenerative diseases.

Design and Development of Benzothiazole-Based Fluorescent Probes for Selective Detection of Aß Aggregates in Alzheimer's Disease.

The formation and accumulation of amyloid beta (Aß) peptide are considered the crucial events that are responsible for the progression of Alzheimer's disease (AD). Herein, we have designed and synthesized a series of fluorescent probes by using electron acceptor-donor end groups interacting with a π-conjugating system for the detection of Aß aggregates. The chemical structure of these probes denoted as RMs, having a conjugated π-system (C═C), showed a maximum emission in PBS (>600 nm), which is the best range for a fluorescent imaging probe. Among all these probes, RM-28 showed an excellent fluorescence property with an emission maximum of >598 nm upon binding to Aß aggregates. RM-28 also showed high sensitivity (7.5-fold) and high affinities toward Aß aggregates (Kd = 175.69 ± 4.8 nM; Ka = 0.5 × 107 M-1). It can cross the blood-brain barrier of mice efficiently. The affinity of RM-28 toward Aß aggregates was observed in 3xTg-AD brain sections of the hippocampus and cortex region using a fluorescent imaging technique, as well as an in vitro fluorescence-based binding assay with Aß aggregates. Moreover, RM-28 is highly specific to Aß aggregates and does not bind with intracellular proteins like bovine serum albumin (BSA) and α-synuclein (α-Syn) aggregates. The results indicate that the probe RM-28 emerges as an efficient and veritable highly specific fluorescent probe for the detection of Aß aggregates in both in vitro and in vivo model systems.

Long non-coding RNA MALAT1 protects against Aß1-42 induced toxicity by regulating the expression of receptor tyrosine kinase EPHA2 via quenching miR-200a/26a/26b in Alzheimer's disease.

Altered expressions of Receptor Tyrosine Kinases (RTK) and non-coding (nc) RNAs are known to regulate the pathophysiology of Alzheimer's disease (AD). However, specific understanding of the roles played, especially the mechanistic and functional roles, by long ncRNAs in AD is still elusive. Using mouse tissue qPCR assays we observe changes in the expression levels of 41 lncRNAs in AD mice of which only 7 genes happen to have both human orthologs and AD associations. Post validation of these 7 human lncRNA genes, MEG3 and MALAT1 shows consistent and significant decrease in AD cell, animal models and human AD brain tissues, but MALAT1 showed a more pronounced decrease. Using bioinformatics, qRT-PCR, RNA FISH and RIP techniques, we could establish MALAT1 as an interactor and regulator of miRs-200a, -26a and -26b, all of which are naturally elevated in AD. We could further show that these miRNAs target the RTK EPHA2 and several of its downstream effectors. Expectedly EPHA2 over expression protects against Aß1-42 induced cytotoxicity. Transiently knocking down MALAT1 validates these unique regulatory facets of AD at the miRNA and protein levels. Although the idea of sponging of miRNAs by lncRNAs in other pathologies is gradually gaining credibility, this novel MALAT1- miR-200a/26a/26b - EPHA2 regulation mechanism in the context of AD pathophysiology promises to become a significant strategy in controlling the disease.

Receptor tyrosine kinase ROR1 ameliorates Aß1-42 induced cytoskeletal instability and is regulated by the miR146a-NEAT1 nexus in Alzheimer's disease.

Alzheimer's disease (AD) involves severe cytoskeletal degradation and microtubule disruption. Here, we studied the altered dynamics of ROR1, a Receptor Tyrosine Kinase (RTK), and how it could counter these abnormalities. We found that in an Aß1-42 treated cell model of AD, ROR1 was significantly decreased. Over expressed ROR1 led to the abrogation of cytoskeletal protein degradation, even in the presence of Aß1-42, preserved the actin network, altered actin dynamics and promoted neuritogenesis. Bioinformatically predicted miRNAs hsa-miR-146a and 34a were strongly up regulated in the cell model and their over expression repressed ROR1. LncRNA NEAT1, an interactor of these miRNAs, was elevated in mice AD brain and cell model concordantly. RNA Immunoprecipitation confirmed a physical interaction between the miRNAs and NEAT1. Intuitively, a transient knock down of NEAT1 increased their levels. To our knowledge, this is the first instance which implicates ROR1 in AD and proposes its role in preserving the cytoskeleton. The signalling modalities are uniquely analyzed from the regulatory perspectives with miR-146a and miR-34a repressing ROR1 and in turn getting regulated by NEAT1.

A nexus of miR-1271, PAX4 and ALK/RYK influences the cytoskeletal architectures in Alzheimer's Disease and Type 2 Diabetes.

Alzheimer's Disease (AD) and Type 2 Diabetes (T2D) share a common hallmark of insulin resistance. Reportedly, two non-canonical Receptor Tyrosine Kinases (RTKs), ALK and RYK, both targets of the same micro RNA miR-1271, exhibit significant and consistent functional down-regulation in post-mortem AD and T2D tissues. Incidentally, both have Grb2 as a common downstream adapter and NOX4 as a common ROS producing factor. Here we show that Grb2 and NOX4 play critical roles in reducing the severity of both the diseases. The study demonstrates that the abundance of Grb2 in degenerative conditions, in conjunction with NOX4, reverse cytoskeletal degradation by counterbalancing the network of small GTPases. PAX4, a transcription factor for both Grb2 and NOX4, emerges as the key link between the common pathways of AD and T2D. Down-regulation of both ALK and RYK through miR-1271, elevates the PAX4 level by reducing its suppressor ARX via Wnt/ß-Catenin signaling. For the first time, this study brings together RTKs beyond Insulin Receptor (IR) family, transcription factor PAX4 and both AD and T2D pathologies on a common regulatory platform.

Withaferin A Induces Heat Shock Response and Ameliorates Disease Progression in a Mouse Model of Huntington's Disease.

Impairment of proteostasis network is one of the characteristic features of many age-related neurodegenerative disorders including autosomal dominantly inherited Huntington's disease (HD). In HD, N-terminal portion of mutant huntingtin protein containing expanded polyglutamine repeats accumulates as inclusion bodies and leads to progressive deterioration of various cellular functioning including proteostasis network. Here we report that Withaferin A (a small bioactive molecule derived from Indian medicinal plant, Withania somnifera) partially rescues defective proteostasis by activating heat shock response (HSR) and delays the disease progression in a HD mouse model. Exposure of Withaferin A activates HSF1 and induces the expression of HSP70 chaperones in an in vitro cell culture system and also suppresses mutant huntingtin aggregation in a cellular model of HD. Withaferin A treatment to HD mice considerably increased their lifespan as well as restored progressive motor behavioral deficits and declined body weight. Biochemical studies confirmed the activation of HSR and global decrease in mutant huntingtin aggregates load accompanied with improvement of striatal function in Withaferin A-treated HD mouse brain. Withaferin A-treated HD mice also exhibit significant decrease in inflammatory processes as evident from the decreased microglial activation. These results indicate immense potential of Withaferin A for the treatment of HD and related neurodegenerative disorders involving protein misfolding and aggregation.

LRSAM1 E3 ubiquitin ligase promotes proteasomal clearance of E6-AP protein.

Numerous proteins participate and actively contribute to the various cellular mechanisms, where several of them are crucial for regular metabolism, including survival. Thus, to maintain optimal cellular physiology, cells govern protein quality control functions with the assistance of comprehensive actions of molecular chaperones, the ubiquitin-proteasome system, and autophagy. In the ubiquitin-proteasome pathway, few quality control E3 ubiquitin ligases actively participate against misfolded protein aggregation generated via stress conditions. But how these quality control E3s active expression levels returned to basal levels when cells achieved re-establishment of proteostasis is still poorly understood. Our current study demonstrated that LRSAM1 E3 ubiquitin ligase promotes the proteasomal degradation of quality control E3 ubiquitin ligase E6-AP. We have observed the co-localization and recruitment of LRSAM1 with E6-AP protein and noticed that LRSAM1 induces the endogenous turnover of E6-AP. Partial depletion of LRSAM1 elevates the levels of E6-AP and affects overall cell cycle regulatory proteins (p53 and p27) expression, including the rate of cellular proliferation. The current finding also provides an excellent opportunity to better understand the basis of the E6-AP associated pathomechanism of Angelman Syndrome disorder. Additionally, this study touches upon the novel potential molecular strategy to regulate the levels of one quality control E3 ubiquitin ligase with another E3 ubiquitin ligase and restore proteostasis and provide a possible therapeutic approach against abnormal protein aggregation diseases.

Simvastatin Restores HDAC1/2 Activity and Improves Behavioral Deficits in Angelman Syndrome Model Mouse.

Angelman syndrome (AS) is a neurodevelopmental disorder categorized by severe disability in intellectual functions and affected by the loss of function of maternally inherited UBE3A gene. Mice deficient for the maternal Ube3a recapitulates many distinguishing behavioral features of the AS and is used as a typical model system to understand the disease pathogenic mechanism. Here, we first show a significant increase in HDAC1 and HDAC2 activities in AS mice brain from as early as embryonic day 16(E16). In depth study further reveals that the deficiency of Ube3a leads to transcriptional up-regulation of both HDAC1 and HDAC2. Restoration of HDAC1 and HDAC2 activities (as evident from the increased acetylation of histones H3 and H4) using simvastatin significantly improves the cognitive deficit and social interaction behavior in AS mice. Simvastatin treatment also restores the reduced level of BDNF in AS mice brain. Finally, we demonstrate that the treatment of simvastatin to primary cortical neuronal culture prepared from AS mice embryo also rescues altered acetylation of histones H3 and H4 and the level of BDNF. These results suggest that simvastatin could be a promising drug for the treatment of AS.

Dietary restriction improves proteostasis and increases life span through endoplasmic reticulum hormesis.

Unfolded protein response (UPR) of the endoplasmic reticulum (UPRER) helps maintain proteostasis in the cell. The ability to mount an effective UPRER to external stress (iUPRER) decreases with age and is linked to the pathophysiology of multiple age-related disorders. Here, we show that a transient pharmacological ER stress, imposed early in development on Caenorhabditis elegans, enhances proteostasis, prevents iUPRER decline with age, and increases adult life span. Importantly, dietary restriction (DR), that has a conserved positive effect on life span, employs this mechanism of ER hormesis for longevity assurance. We found that only the IRE-1-XBP-1 branch of UPRER is required for the longevity effects, resulting in increased ER-associated degradation (ERAD) gene expression and degradation of ER resident proteins during DR. Further, both ER hormesis and DR protect against polyglutamine aggregation in an IRE-1-dependent manner. We show that the DR-specific FOXA transcription factor PHA-4 transcriptionally regulates the genes required for ER homeostasis and is required for ER preconditioning-induced life span extension. Finally, we show that ER hormesis improves proteostasis and viability in a mammalian cellular model of neurodegenerative disease. Together, our study identifies a mechanism by which DR offers its benefits and opens the possibility of using ER-targeted pharmacological interventions to mimic the prolongevity effects of DR.

Down-Regulation of miRNA-708 Promotes Aberrant Calcium Signaling by Targeting Neuronatin in a Mouse Model of Angelman Syndrome.

The expression of ubiquitin ligase UBE3A is paternally imprinted in neurons and loss of function of maternally inherited UBE3A causes Angelman syndrome (AS), a neurodevelopmental disorder characterized by severe intellectual disability and motor disturbances. Over activation of UBE3A is also linked with autism. Mice deficient for maternal Ube3a (AS mice) exhibit various behavioral features of AS including cognitive and motor deficits although the underlying molecular mechanism is poorly understood. Here, we investigated possible involvement of miRNA in AS pathogenesis and identified miR-708 as one of the down-regulated miRNA in the brain of AS mice. This miR-708 targets endoplasmic reticulum resident protein neuronatin (a developmentally regulated protein in the brain) leading to decrease in intracellular Ca2+. Suppression of miR-708 or ectopic expression of neuronatin increased the level of intracellular Ca2+ and phosphorylation of CaMKIIα at Thr286. Neuronatin level was significantly increased in various brain regions of AS mice during embryonic and early postnatal days as well as in parvalbumin-positive GABAergic neurons during adulthood with respect to age-matched wild type controls. Differentiated cultured primary cortical neurons obtained from AS mice brain also exhibited higher expression of neuronatin, increased intracellular basal Ca2+ along with augmented phosphorylation of CaMKIIα at Thr286. These results indicate that miR-708/neuronatin mediated aberrant calcium signaling might be implicated in AS pathogenesis.

LRSAM1 E3 ubiquitin ligase: molecular neurobiological perspectives linked with brain diseases.

Cellular protein quality control (PQC) plays a significant role in the maintenance of cellular homeostasis. Failure of PQC mechanism may lead to various neurodegenerative diseases due to accumulation of aberrant proteins. To avoid such fatal neuronal conditions PQC employs autophagy and ubiquitin proteasome system (UPS) to degrade misfolded proteins. Few quality control (QC) E3 ubiquitin ligases interplay an important role to specifically recognize misfolded proteins for their intracellular degradation. Leucine-rich repeat and sterile alpha motif-containing 1 (LRSAM1) is a really interesting new gene (RING) class protein that possesses E3 ubiquitin ligase activity with promising applications in PQC. LRSAM1 is also known as RING finger leucine repeat rich (RIFLE) or TSG 101-associated ligase (TAL). LRSAM1 has various cellular functions as it modulates the protein aggregation, endosomal sorting machinery and virus egress from the cells. Thus, this makes LRSAM1 interesting to study not only in protein conformational disorders such as neurodegeneration but also in immunological and other cancerous disorders. Furthermore, LRSAM1 interacts with both cellular protein degradation machineries and hence it can participate in maintenance of overall cellular proteostasis. Still, more research work on the quality control molecular functions of LRSAM1 is needed to comprehend its roles in various protein aggregatory diseases. Earlier findings suggest that in a mouse model of Charcot-Marie-Tooth (CMT) disease, lack of LRSAM1 functions sensitizes peripheral axons to degeneration. It has been observed that in CMT the patients retain dominant and recessive mutations of LRSAM1 gene, which encodes most likely a defective protein. However, still the comprehensive molecular pathomechanism of LRSAM1 in neuronal functions and neurodegenerative diseases is not known. The current article systematically represents the molecular functions, nature and detailed characterization of LRSAM1 E3 ubiquitin ligase. Here, we review emerging molecular mechanisms of LRSAM1 linked with neurobiological functions, with a clear focus on the mechanism of neurodegeneration and also on other diseases. Better understanding of LRSAM1 neurobiological and intracellular functions may contribute to develop promising novel therapeutic approaches, which can also propose new lines of molecular beneficial targets for various neurodegenerative diseases.

UBE3A and Its Link With Autism.

UBE3A is a dual function protein consisting of ubiquitin ligase as well as transcriptional co-activator function. UBE3A gene is imprinted in the brain with preferential maternal-specific expression particularly in the neuron and loss of activity of the maternally inherited UBE3A causes Angelman syndrome (AS), characterized by severe mental retardation, lack of speech, seizures and autistic features. Interestingly, duplication, triplication, or gain-of-function mutations in the UBE3A gene are also linked with autism clinically distinguished by social impairments and stereotyped behaviors. These findings indicate that the expression and activity of UBE3A must be tightly regulated during brain development and UBE3A might be playing a crucial role in controlling synaptic function and plasticity through proteasome-mediated degradation as well as transcriptional regulation of its target proteins. In fact, several recent reports demonstrated the role of UBE3A in the modulation of synaptic function and plasticity. This review focuses on the critical role of UBE3A in regulating the synaptic function and how its altered activity is associated with autism.

Glycogen synthase protects neurons from cytotoxicity of mutant huntingtin by enhancing the autophagy flux.

Healthy neurons do not store glycogen while they do possess the machinery for the glycogen synthesis albeit at an inactive state. Neurons in the degenerating brain, however, are known to accumulate glycogen, although its significance was not well understood. Emerging reports present contrasting views on neuronal glycogen synthesis; a few reports demonstrate a neurotoxic effect of glycogen while a few others suggest glycogen to be neuroprotective. Thus, the specific role of glycogen and glycogen synthase in neuronal physiology is largely unexplored. Using cellular and animal models of Huntington's disease, we show here that the overexpression of cytotoxic mutant huntingtin protein induces glycogen synthesis in the neurons by activating glycogen synthase and the overexpressed glycogen synthase protected neurons from the cytotoxicity of the mutant huntingtin. Exposure of neuronal cells to proteasomal blockade and oxidative stress also activate glycogen synthase to induce glycogen synthesis and to protect against stress-induced neuronal death. We show that the glycogen synthase plays an essential and inductive role in the neuronal autophagic flux, and helps in clearing the cytotoxic huntingtin aggregate. We also show that the increased neuronal glycogen inhibits the aggregation of mutant huntingtin, and thus could directly contribute to its clearance. Finally, we demonstrate that excessive autophagy flux is the molecular basis of cell death caused by the activation of glycogen synthase in unstressed neurons. Taken together, our results thus provide a novel function for glycogen synthase in proteolytic processes and offer insight into the role of glycogen synthase and glycogen in both survival and death of the neurons.

Azadiradione Restores Protein Quality Control and Ameliorates the Disease Pathogenesis in a Mouse Model of Huntington's Disease.

Huntington's disease (HD) is an autosomal dominantly inherited neurodegenerative disorder caused by expansion of CAG repeats in the coding area of huntingtin gene. In the HD brain, mutant huntingtin protein goes through proteolysis, and its amino-terminal portion consisting of polyglutamine repeats accumulate as inclusions that result in progressive impairment of cellular protein quality control system. Here, we demonstrate that partial rescue of the defective protein quality control in HD model mouse by azadiradione (a bioactive limonoids found in the seed of Azadirachta indica) could potentially improve the disease pathology. Prolonged treatment of azadiradione to HD mice significantly improved the progressive deterioration in body weight, motor functioning along with extension of lifespan. Azadiradione-treated HD mice brain also exhibited considerable decrease in mutant huntingtin aggregates load and improvement of striatal pathology in comparison with age-matched saline-treated HD controls. Biochemical analysis further revealed upregulation and activation of not only HSF1 (master regulator of protein folding) but also Ube3a (an ubiquitin ligase involved in the clearance of mutant huntingtin) in azadiradione-treated mice. Our results indicate that azadiradione-mediated enhanced folding and clearance of mutant huntingtin might underlie improved disease pathology in HD mice and suggests that it could be a potential therapeutic molecule to delay the progression of HD.

Ube3a deficiency inhibits amyloid plaque formation in APPswe/PS1δE9 mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive decline in memory and cognitive function. Pathological hallmark of AD includes aberrant aggregation of amyloid beta (Aß) peptide, which is produced upon sequential cleavage of amyloid precursor protein (APP) by ß- and γ -secretases. On the contrary, α-secretase cleaves APP within the Aß sequence and thereby prevents Aß generation. Here, we investigated the role of ubiquitin ligase Ube3a (involved in synaptic function and plasticity) in the pathogenesis of AD using APPswe/PS1δE9 transgenic mouse model and first noticed that soluble pool of Ube3a was age-dependently decreased in AD mouse in comparison with wild type controls. To further explore the role of Ube3a in AD patho-mechanism, we generated brain Ube3a-deficient AD mice that exhibited accelerated cognitive and motor deficits compared with AD mice. Interestingly, these Ube3a-deficient AD mice were excessively obese from their age of 12 months and having shorter lifespan. Biochemical analysis revealed that the Ube3a-deficient AD mice had significantly reduced level of Aß generation and amyloid plaque formation in their brain compared with age-matched AD mice and this effect could be due to the increased activity of α-secretase, ADAM10 (a disintegrin and metalloproteinase-10) that shift the proteolysis of APP towards non-amyloidogenic pathway. These findings suggest that aberrant function of Ube3a could influence the progression of AD and restoring normal level of Ube3a might be beneficial for AD.

Progressing neurobiological strategies against proteostasis failure: Challenges in neurodegeneration.

Proteins are ordered useful cellular entities, required for normal health and organism's survival. The proteome is the absolute set of cellular expressed proteins, which regulates a wide range of physiological functions linked with all domains of life. In aging cells or under unfavorable cellular conditions, misfolding of proteins generates common pathological events linked with neurodegenerative diseases and aging. Current advances of proteome studies systematically generates some progress in our knowledge that how misfolding of proteins or their accumulation can contribute to the impairment or depletion of proteome functions. Still, the underlying causes of this unrecoverable loss are not clear that how such unsolved transitions give rise to multifactorial challengeable degenerative pathological conditions in neurodegeneration. In this review, we specifically focus and systematically summarize various molecular mechanisms of proteostasis maintenance, as well as discuss progressing neurobiological strategies, promising natural and pharmacological candidates, which can be useful to counteract the problem of proteopathies. Our article emphasizes an urgent need that now it is important for us to recognize the fundamentals of proteostasis to design a new molecular framework and fruitful strategies to uncover how the proteome defects are associated with aging and neurodegenerative diseases. A enhance understanding of progress link with proteome and neurobiological challenges may provide new basic concepts in the near future, based on pharmacological agents, linked with impaired proteostasis and neurodegenerative diseases.

Rescue of altered HDAC activity recovers behavioural abnormalities in a mouse model of Angelman syndrome.

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by severe intellectual and developmental disabilities. The disease is caused by the loss of function of maternally inherited UBE3A, a gene that exhibits paternal-specific imprinting in neuronal tissues. Ube3a-maternal deficient mice (AS mice) display many classical features of AS, although, the underlying mechanism of these behavioural deficits is poorly understood. Here we report that the absence of Ube3a in AS mice brain caused aberrant increase in HDAC1/2 along with decreased acetylation of histone H3/H4. Partial knockdown of Ube3a in cultured neuronal cells also lead to significant up-regulation of HDAC1/2 and consequent down-regulation of histones H3/H4 acetylation. Treatment of HDAC inhibitor, sodium valproate, to AS mice showed significant improvement in social, cognitive and motor impairment along with restoration of various proteins linked with synaptic function and plasticity. Interestingly, HDAC inhibitor also significantly increased the expression of Ube3a in cultured neuronal cells and in the brain of wild type mice but not in AS mice. These results indicate that anomalous HDAC1/2 activity might be linked with synaptic dysfunction and behavioural deficits in AS mice and suggests that HDAC inhibitors could be potential therapeutic molecule for the treatment of the disease.

Cellular levels of Grb2 and cytoskeleton stability are correlated in a neurodegenerative scenario.

Alzheimer's disease (AD) manifests as neuronal loss. On the premise of Grb2 overexpression in AD mouse brain and brain tissues of AD patients, our study primarily focuses on the stability of cytoskeletal proteins in the context of degenerative AD-like conditions. Two predominant molecular features of AD, extracellular accumulation of ß-amyloid oligomers and intracellular elevation of amyloid precursor protein intracellular domain levels, have been used to closely inspect the series of signalling events. In their presence, multiple signalling pathways involving ROCK and PAK1 proteins lead to disassembly of the cytoskeleton, and Grb2 partially counterbalances the cytoskeletal loss. Increased Grb2-NOX4 interactions play a preventive role against cytoskeletal disassembly, in turn blocking the activity of nitrogen oxides and decreasing the expression of slingshot homolog 1 (SSH-1) protein, a potent inducer of cytoskeleton disassembly. This study unravels a unique role of Grb2 in protecting the cytoskeletal architecture in AD-like conditions and presents a potential new strategy for controlling neurodegeneration.

Environmental Enrichment Improves Behavioral Abnormalities in a Mouse Model of Angelman Syndrome.

Angelman syndrome (AS) is a neurodevelopmental disorder largely caused by the loss of function of maternally inherited UBE3A. UBE3A-maternal deficient mice (AS mice) exhibit many typical features of AS including cognitive and motor deficits but the underlying mechanism of these behavioral abnormalities is poorly understood. Here, we demonstrate that rearing of AS mice in the enriched environment for prolonged period significantly improved their cognitive and motor dysfunction. Enriched environment also restored elevated serum corticosterone level and reduced anxiety-like behaviors in these mice. Biochemical analysis further revealed restoration of altered levels of brain-derived neurotrophic factor, glucocorticoid receptor, and phoshphorylated calcium/calmodulin-dependent protein kinase IIα in the hippocampus of AS mice maintained in the enriched environment. Enriched environment also significantly increased the number of parvalbumin-positive GABAergic interneuron in the hippocampus and basolateral amygdala of AS mice. These results indicate potential beneficial effect of enriched environment in the reversal of AS phenotype.

Topoisomerase 1 inhibitor topotecan delays the disease progression in a mouse model of Huntington's disease.

Huntington's disease (HD) is a dominantly inherited progressive neurodegenerative disorder caused by the accumulation of polyglutamine expanded mutant huntingtin as inclusion bodies primarily in the brain. After the discovery of the HD gene, considerable progress has been made in understanding the disease pathogenesis and multiple drug targets have been identified, even though currently there is no effective therapy. Here, we demonstrate that the treatment of topotecan, a brain-penetrating topoisomerase 1 inhibitor, to HD transgenic mouse considerably improved its motor behavioural abnormalities along with a significant extension of lifespan. Improvement of behavioural deficits are accompanied with the significant rescue of their progressively decreased body weight, brain weight and striatal volume. Interestingly, topotecan treatment also significantly reduced insoluble mutant huntingtin load in the HD mouse brain. Finally, we show that topotecan treatment to HD mouse not only inhibits the expression of transgenic mutant huntingtin, but also at the same time induces the expression of Ube3a, an ubiquitin ligase linked to the clearance of mutant huntingtin. These findings suggest that topotecan could be a potential therapeutic molecule to delay the progression of HD.