New insights on neurodegeneration triggered by iron accumulation: Intersections with neutral lipid metabolism, ferroptosis, and motor impairment.

Brain iron accumulation constitutes a pathognomonic indicator in several neurodegenerative disorders. Metal accumulation associated with dopaminergic neuronal death has been documented in Parkinson's disease. Through the use of in vivo and in vitro models, we demonstrated that lipid dysregulation manifests as a neuronal and glial response during iron overload. In this study, we show that cholesterol content and triacylglycerol (TAG) hydrolysis were strongly elevated in mice midbrain. Lipid cacostasis was concomitant with the loss of dopaminergic neurons, astrogliosis and elevated expression of α-synuclein. Exacerbated lipid peroxidation and markers of ferroptosis were evident in the midbrain from mice challenged with iron overload. An imbalance in the activity of lipolytic and acylation enzymes was identified, favoring neutral lipid hydrolysis, and consequently reducing TAG and cholesteryl ester levels. Notably, these observed alterations were accompanied by motor impairment in iron-treated mice. In addition, neuronal and glial cultures along with their secretomes were used to gain further insight into the mechanism underlying TAG hydrolysis and cholesterol accumulation as cellular responses to iron accumulation. We demonstrated that TAG hydrolysis in neurons is triggered by astrocyte secretomes. Moreover, we found that the ferroptosis inhibitor, ferrostatin-1, effectively prevents cholesterol accumulation both in neurons and astrocytes. Taken together, these results indicate that lipid disturbances occur in iron-overloaded mice as a consequence of iron-induced oxidative stress and depend on neuron-glia crosstalk. Our findings suggest that developing therapies aimed at restoring lipid homeostasis may lead to specific treatment for neurodegeneration associated with ferroptosis and brain iron accumulation.

Vitamin E Analog Trolox Attenuates MPTP-Induced Parkinson's Disease in Mice, Mitigating Oxidative Stress, Neuroinflammation, and Motor Impairment.

Trolox is a potent antioxidant and a water-soluble analog of vitamin E. It has been used in scientific studies to examine oxidative stress and its impact on biological systems. Trolox has been shown to have a neuroprotective effect against ischemia and IL-1ß-mediated neurodegeneration. In this study, we investigated the potential protective mechanisms of Trolox against a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease mouse model. Western blotting, immunofluorescence staining, and ROS/LPO assays were performed to investigate the role of trolox against neuroinflammation, the oxidative stress mediated by MPTP in the Parkinson's disease (PD) mouse model (wild-type mice (C57BL/6N), eight weeks old, average body weight 25-30 g). Our study showed that MPTP increased the expression of α-synuclein, decreased tyrosine hydroxylase (TH) and dopamine transporter (DAT) levels in the striatum and substantia nigra pars compacta (SNpc), and impaired motor function. However, Trolox treatment significantly reversed these PD-like pathologies. Furthermore, Trolox treatment reduced oxidative stress by increasing the expression of nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Lastly, Trolox treatment inhibited the activated astrocytes (GFAP) and microglia (Iba-1), also reducing phosphorylated nuclear factor-κB, (p-NF-κB) and tumor necrosis factor-alpha (TNF-α) in the PD mouse brain. Overall, our study demonstrated that Trolox may exert neuroprotection on dopaminergic neurons against MPTP-induced oxidative stress, neuroinflammation, motor dysfunction, and neurodegeneration.

CSMD3 Deficiency Leads to Motor Impairments and Autism-Like Behaviors via Dysfunction of Cerebellar Purkinje Cells in Mice.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with highly heritable heterogeneity. Mutations of CUB and sushi multiple domains 3 (CSMD3) gene have been reported in individuals with ASD. However, the underlying mechanisms of CSMD3 for the onset of ASD remain unexplored. Here, using male CSMD3 knock-out (CSMD3 -/-) mice, we found that genetic deletion of CSMD3 produced core autistic-like symptoms (social interaction deficits, restricted interests, and repetitive and stereotyped behaviors) and motor dysfunction in mice, indicating that the CSMD3 gene can be considered as a candidate for ASD. Moreover, we discovered that the ablation of CSMD3 in mice led to abnormal cerebellar Purkinje cell (PC) morphology in Crus I/II lobules, including aberrant developmental dendritogenesis and spinogenesis of PCs. Furthermore, combining in vivo fiber photometry calcium imaging and ex vivo electrophysiological recordings, we showed that the CSMD3 -/- mice exhibited an increased neuronal activity (calcium fluorescence signals) in PCs of Crus I/II lobules in response to movement activity, as well as an enhanced intrinsic excitability of PCs and an increase of excitatory rather than inhibitory synaptic input to the PCs, and an impaired long-term depression at the parallel fiber-PC synapse. These results suggest that CSMD3 plays an important role in the development of cerebellar PCs. Loss of CSMD3 causes abnormal PC morphology and dysfunction in the cerebellum, which may underlie the pathogenesis of motor deficits and core autistic-like symptoms in CSMD3 -/- mice. Our findings provide novel insight into the pathophysiological mechanisms by which CSMD3 mutations cause impairments in cerebellar function that may contribute to ASD.SIGNIFICANCE STATEMENT Autism spectrum disorder (ASD) is a neurodevelopmental disorder with highly heritable heterogeneity. Advances in genomic analysis have contributed to numerous candidate genes for the risk of ASD. Recently, a novel giant gene CSMD3 encoding a protein with CUB and sushi multiple domains (CSMDs) has been identified as a candidate gene for ASD. However, the underlying mechanisms of CSMD3 for the onset of ASD remain largely unknown. Here, we unravel that loss of CSMD3 results in abnormal morphology, increased intrinsic excitabilities, and impaired synaptic plasticity in cerebellar PCs, subsequently leading to motor deficits and ASD-like behaviors in mice. These results provide novel insight into the pathophysiological mechanisms by which CSMD3 mutations cause impairments in cerebellar function that may contribute to ASD.

Constraint-induced movement therapy alleviates motor impairment by inhibiting the accumulation of neutrophil extracellular traps in ischemic cortex.

Stroke is a major cause of mortality and morbidity and most acute strokes are ischemic. Evidence-based medicine has demonstrated the effectiveness of constraint-induced movement therapy (CIMT) in the recovery of motor function in patients after ischemic stroke, but the specific treatment mechanism remains unclear. Herein, our integrated transcriptomics and multiple enrichment analysis studies, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) studies show that CIMT conduction broadly curtails immune response, neutrophil chemotaxis, and chemokine-mediated signaling pathway, CCR chemokine receptor binding. Those suggest the potential effect of CIMT on neutrophils in ischemic mice brain parenchyma. Recent studies have found that accumulating granulocytes release extracellular web-like structures composed of DNA and proteins called neutrophil extracellular traps (NETs), which destruct neurological function primarily by disrupting the blood-brain barrier and promoting thrombosis. However, the temporal and spatial distribution of neutrophils and their released NETs in parenchyma and their damaging effects on nerve cells remain unclear. Thus, utilizing immunofluorescence and flow cytometry, our analyses uncovered that NETs erode multiple regions such as primary motor cortex (M1), striatum (Str), nucleus of the vertical limb of the diagonal band (VDB), nucleus of the horizontal limb of the diagonal band (HDB) and medial septal nucleus (MS), and persist in the brain parenchyma for at least 14 days, while CIMT can reduce the content of NETs and chemokines CCL2 and CCL5 in M1. Intriguingly, CIMT failed to further reduce neurological deficits after inhibiting the NET formation by pharmacologic inhibition of peptidylarginine deiminase 4 (PAD4). Collectively, these results demonstrate that CIMT could alleviate cerebral ischemic injury induced locomotor deficits by modulating the activation of neutrophils. These data are expected to provide direct evidence for the expression of NETs in ischemic brain parenchyma and novel insights into the mechanisms of CIMT protecting against ischemic brain injury.

Microglial depletion exacerbates motor impairment and dopaminergic neuron loss in a 6-OHDA model of Parkinson's disease.

6-hydroxydopamine (6-OHDA) is a common neurotoxin used to induce Parkinson's disease (PD) in mice, exerting neurotoxic effects through the production of reactive oxygen species and microglial activation. However, the role of microglia in PD is still not clear, with contradictory reports showing neuroprotection or exacerbation of neuronal death. Microglial depletion aggravates motor coordination impairments and reduces tyrosine hydroxylase positive neurons in the substantia nigra pars compacta. Moreover, MeCP2 and Adora1 genes expression were downregulated, suggesting they may be involved in the neurodegenerative process. This study highlights that microglia plays a protective role in dopaminergic neuron survival during the initial phase of PD, and the investigation of the mechanisms of this effect in future studies will help elucidate the pathophysiology of PD.

Chronic acrylamide exposure resulted in dopaminergic neuron loss, neuroinflammation and motor impairment in rats.

Acrylamide (ACR) as a by-product of Maillard reaction is widely present in food. Although ACR is known to exhibit neurotoxicity, most studies about ACR neurotoxicity are currently short-term high-dose providing limited reference value for human exposure. The present study aims to determine the effects of chronic ACR exposure on dopaminergic neurons in rat nigra and the potential mechanism from the perspective of NLRP3 inflammasome-mediated neuroinflammation. The SD rats were maintained on treated drinking water providing dosages of 0, 0.5, or 5 mg/kg/day ACR for 12 months. ACR exposure caused motor dysfunction in rats, which was associated with dopaminergic neuron loss, α-Synuclein (α-Syn) accumulation and decreased brain-derived neurotrophic factor (BDNF) in nigra. ACR activated microglia by increasing Iba-1+, Iba-1+CD68+ positive cells and the percentage of ameboid-shaped ones in rat nigra. ACR markedly upregulated the protein levels of NLRP3 inflammasome constituents NLRP3 and caspase-1 and inflammatory cytokine IL-1ß. ACR chronic exposure increased the risk of Parkinson's disease (PD) like dopaminergic neuron depletion in nigra potentially through NLRP3 inflammasome-mediated neuroinflammtion.

4-Phenylbutyrate Mitigates the Motor Impairment and Dopaminergic Neuronal Death During Parkinson's Disease Pathology via Targeting VDAC1 Mediated Mitochondrial Function and Astrocytes Activation.

Parkinson's disease (PD) is a progressive motor neurodegenerative disorder significantly associated with protein aggregation related neurodegenerative mechanisms. In view of no disease modifying drugs, the present study was targeted to investigate the therapeutic effects of pharmacological agent 4-phenylbutyric acid (4PBA) in PD pathology. 4PBA is an FDA approved monocarboxylic acid with inhibitory activity towards histone deacetylase and clinically treats urea cycle disorder. First, we observed the significant protective effects of 4PBA on PD specific neuromuscular coordination, level of tyrosine hydroxylase, α-synuclein level and neurotransmitter dopamine in both substantia nigra and striatal regions of the experimental rat model of PD. Further results revealed that treatment with 4PBA drug exhibited significant protection against disease related oxidative stress and augmented nitrite levels. The disease pathology-related depletion in mitochondrial membrane potential and augmented level of calcium as well as mitochondrion membrane located VDAC1 protein level and cytochrome-c translocation were also significantly attenuated with 4PBA administration. Inhibited neuronal apoptosis and restored neuronal morphology were also observed with 4PBA treatment as measured by level of pro-apoptotic proteins t-Bid, Bax and cleaved caspase-3 along with cresyl violet staining in both substantia nigra and striatal regions. Lastly, PD-linked astrocyte activation was significantly inhibited with 4PBA treatment. Altogether, our findings suggest that 4PBA exerts broad-spectrum neuroprotective effects in PD animal model.

Single-nucleus RNA sequencing identified cells with ependymal cell-like features enriched in neonatal mice after spinal cord injury.

The adult mammalian central nervous system has limited regenerative ability, and spinal cord injury (SCI) often causes lifelong motor disability. While regeneration is limited in adults, injured spinal cord tissue can be regenerated and neural function can be almost completely restored in neonates. However, difference of cellular composition in lesion has not been well characterized. To gain insight into the age-dependent cellular reaction after SCI, we performed single-nucleus RNA sequencing, analyzing 4076 nuclei from sham and injured spinal cords from adult and neonatal mice. Clustering analysis identified 18 cell populations. We identified previously undescribed cells with ependymal cell-like gene expression profile, the number of which was increased in neonates after SCI. Histological analysis revealed that these cells line the central canal under physiological conditions in both adults and neonates. We confirmed that they were enriched in the lesion only in neonates. We further showed that these cells were positive for the cellular markers of ependymal cells, astrocytes and radial glial cells. This study provides a deeper understanding of neonate-specific cellular responses after SCI, which may determine regenerative capacity.

Mitochondrial dysfunction and oxidative stress contribute to cognitive and motor impairment in FOXP1 syndrome.

FOXP1 syndrome caused by haploinsufficiency of the forkhead box protein P1 (FOXP1) gene is a neurodevelopmental disorder that manifests motor dysfunction, intellectual disability, autism, and language impairment. In this study, we used a Foxp1+/- mouse model to address whether cognitive and motor deficits in FOXP1 syndrome are associated with mitochondrial dysfunction and oxidative stress. Here, we show that genes with a role in mitochondrial biogenesis and dynamics (e.g., Foxo1, Pgc-1α, Tfam, Opa1, and Drp1) were dysregulated in the striatum of Foxp1+/- mice at different postnatal stages. Furthermore, these animals exhibit a reduced mitochondrial membrane potential and complex I activity, as well as decreased expression of the antioxidants superoxide dismutase 2 (Sod2) and glutathione (GSH), resulting in increased oxidative stress and lipid peroxidation. These features can explain the reduced neurite branching, learning and memory, endurance, and motor coordination that we observed in these animals. Taken together, we provide strong evidence of mitochondrial dysfunction in Foxp1+/- mice, suggesting that insufficient energy supply and excessive oxidative stress underlie the cognitive and motor impairment in FOXP1 deficiency.

Creatinine-to-cystatin C ratio estimates muscle mass correlating the markers of the patients with severe motor and intellectual disabilities.

AIM: The creatinine-to-cystatin C ratio (CCR) has been acknowledged as a potential marker of muscle mass. The purpose of the present study was to evaluate the relationship between CCR and nutritional status in a bioelectrical impedance analysis (BIA) of patients with severe motor and intellectual disabilities (SMID). METHODS: This study included 39 patients with SMID (17 males, 22 females) over 16 years of age were included retrospectively. CCR was calculated as serum creatinine (mg/dL)/cystatin C (mg/L) × 10. The BIA parameters such as the phase angle (PhA), fat free mass (FFM), appendicular skeletal muscle mass (ASM) and appendicular skeletal muscle mass index (ASMI) values were measured using BIA. Correlation analyses between CCR and the BIA parameters were conducted. RESULTS: The mean CCR is 4.47 ±â€¯1.34. Significant positive relationships between CCR and FFM, PhA, ASM, ASMI were identified (r = 0.3373, p = 0.0357. r = 0.4273, p = 0.0093. r = 0.5008, p = 0.0012. r = 0.4706, p = 0.0025 and r = 0.4751, p = 0.0022, respectively). CONCLUSIONS: The study indicated that CCR in the patients with SMID is a useful parameter that allows for the muscle mass to be estimated easily and accurately. This means that evaluating CCR could be used as a simple and important screening tool for PhA, FFM and muscle mass.

Mice lacking 5-lipoxygenase display motor deficits associated with cortical and hippocampal synapse abnormalities.

Neural-immune interactions are related to the synapse plasticity and other dynamic processes in the nervous system. The absence or dysfunction of cellular/molecular elements from the immune system lead to impairments in the central and peripheral nervous system with behavior consequences such as cognitive, sensory, and locomotor deficits as well as social disabilities and anxiety disturbances. Cellular interactions between immune cells such as macrophages, microglia, and neutrophils with glial or neuronal cells have been of increasing interest over the last years. However, little is known about the role of immune-derived soluble factors in the context of homeostasis of the nervous system. Leukotrienes (LTs) are lipid mediators derived from the oxidation of arachidonic acid by 5-lipoxygenase (5-LO), and are classically involved in inflammation, allergies, and asthma. Here, we demonstrated that adult mice lacking 5-LO (5-LO-/-) showed motor deficits in rotarod test and increased repetitive behavior (marble burying test). These behavioral changes are accompanied by increased levels of synapse proteins (PSD95 and synaptophysin) at the motor cortex and hippocampus, but not with BDNF alterations. No changes in microglial cell density or morphology were seen in the brains of 5-LO-/- mice. Furthermore, expression of fractalkine receptor CX3CR1 was increased and of its ligand CX3CL1 was decreased in the cortex of 5-LO-/- mice. Here we provide evidence for the involvement of 5-LO products structuring synapses network with motor behavior consequences. We suggest that the absence of 5-LO products lead to modified microglial/neuron interaction, reducing microglial pruning.

Suppression of Kv3.3 channels by antisense oligonucleotides reverses biochemical effects and motor impairment in spinocerebellar ataxia type 13 mice.

Mutations in KCNC3, the gene that encodes the Kv3.3 voltage dependent potassium channel, cause Spinocerebellar Ataxia type 13 (SCA13), a disease associated with disrupted motor behaviors, progressive cerebellar degeneration, and abnormal auditory processing. The Kv3.3 channel directly binds Hax-1, a cell survival protein. A disease-causing mutation, Kv3.3-G592R, causes overstimulation of Tank Binding Kinase 1 (Tbk1) in the cerebellum, resulting in the degradation of Hax-1 by promoting its trafficking into multivesicular bodies and then to lysosomes. We have now tested the effects of antisense oligonucleotides (ASOs) directed against the Kv3.3 channel on both wild type mice and those bearing the Kv3.3-G592R-encoding mutation. Intracerebroventricular infusion of the Kcnc3-specific ASO suppressed both mRNA and protein levels of the Kv3.3 channel. In wild-type animals, this produced no change in levels of activated Tbk1, Hax-1 or Cd63, a tetraspanin marker for late endosomes/multivesicular bodies. In contrast, in mice homozygous for the Kv3.3-G592R-encoding mutation, the same ASO reduced Tbk1 activation and levels of Cd63, while restoring the expression of Hax-1 in the cerebellum. The motor behavior of the mice was tested using a rotarod assay. Surprisingly, the active ASO had no effects on the motor behavior of wild type mice but restored the behavior of the mutant mice to those of age-matched wild type animals. Our findings indicate that, in mature intact animals, suppression of Kv3.3 expression can reverse the deleterious effects of a SCA13 mutation while having little effect on wild type animals. Thus, targeting Kv3.3 expression may prove a viable therapeutic approach for SCA13.

Small molecule inhibitors of α-synuclein oligomers identified by targeting early dopamine-mediated motor impairment in C. elegans.

BACKGROUND: Parkinson's disease is a disabling neurodegenerative movement disorder characterized by dopaminergic neuron loss induced by α-synuclein oligomers. There is an urgent need for disease-modifying therapies for Parkinson's disease, but drug discovery is challenged by lack of in vivo models that recapitulate early stages of neurodegeneration. Invertebrate organisms, such as the nematode worm Caenorhabditis elegans, provide in vivo models of human disease processes that can be instrumental for initial pharmacological studies. METHODS: To identify early motor impairment of animals expressing α-synuclein in dopaminergic neurons, we first used a custom-built tracking microscope that captures locomotion of single C. elegans with high spatial and temporal resolution. Next, we devised a method for semi-automated and blinded quantification of motor impairment for a population of simultaneously recorded animals with multi-worm tracking and custom image processing. We then used genetic and pharmacological methods to define the features of early motor dysfunction of α-synuclein-expressing C. elegans. Finally, we applied the C. elegans model to a drug repurposing screen by combining it with an artificial intelligence platform and cell culture system to identify small molecules that inhibit α-synuclein oligomers. Screen hits were validated using in vitro and in vivo mammalian models. RESULTS: We found a previously undescribed motor phenotype in transgenic α-synuclein C. elegans that correlates with mutant or wild-type α-synuclein protein levels and results from dopaminergic neuron dysfunction, but precedes neuronal loss. Together with artificial intelligence-driven in silico and in vitro screening, this C. elegans model identified five compounds that reduced motor dysfunction induced by α-synuclein. Three of these compounds also decreased α-synuclein oligomers in mammalian neurons, including rifabutin which has not been previously investigated for Parkinson's disease. We found that treatment with rifabutin reduced nigrostriatal dopaminergic neurodegeneration due to α-synuclein in a rat model. CONCLUSIONS: We identified a C. elegans locomotor abnormality due to dopaminergic neuron dysfunction that models early α-synuclein-mediated neurodegeneration. Our innovative approach applying this in vivo model to a multi-step drug repurposing screen, with artificial intelligence-driven in silico and in vitro methods, resulted in the discovery of at least one drug that may be repurposed as a disease-modifying therapy for Parkinson's disease.

Antisense therapy in a rat model of Alexander disease reverses GFAP pathology, white matter deficits, and motor impairment.

Alexander disease (AxD) is a devastating leukodystrophy caused by gain-of-function mutations in GFAP, and the only available treatments are supportive. Recent advances in antisense oligonucleotide (ASO) therapy have demonstrated that transcript targeting can be a successful strategy for human neurodegenerative diseases amenable to this approach. We have previously used mouse models of AxD to show that Gfap-targeted ASO suppresses protein accumulation and reverses pathology; however, the mice have a mild phenotype with no apparent leukodystrophy or overt clinical features and are therefore limited for assessing functional outcomes. In this report, we introduce a rat model of AxD that exhibits hallmark pathology with GFAP aggregation in the form of Rosenthal fibers, widespread astrogliosis, and white matter deficits. These animals develop normally during the first postnatal weeks but fail to thrive after weaning and develop severe motor deficits as they mature, with about 14% dying of unknown cause between 6 and 12 weeks of age. In this model, a single treatment with Gfap-targeted ASO provides long-lasting suppression, reverses GFAP pathology, and, depending on age of treatment, prevents or mitigates white matter deficits and motor impairment. In this report, we characterize an improved animal model of AxD with myelin pathology and motor impairment, recapitulating prominent features of the human disease, and use this model to show that ASO therapy has the potential to not only prevent but also reverse many aspects of disease.

A Parkinson's disease patient displaying increased neuromelanin-sensitive areas in the substantia nigra after rehabilitation with tDCS: a case report.

Previous studies have reported that transcranial direct current stimulation (tDCS) of the frontal polar area (FPA) ameliorated motor disability in patients with Parkinson's disease (PD). Here we report changes in neuromelanin (NM) imaging of dopaminergic neurons before and after rehabilitation combined with anodal tDCS over the FPA for 2 weeks in a PD patient. After the intervention, the patient showed clinically meaningful improvements while the NM-sensitive area in the SN increased by 18.8%. This case study is the first report of NM imaging of the SN in a PD patient who received tDCS.Abbreviations FPA: front polar area; PD: Parkinson's disease; NM: neuromelanin; DCI: DOPA decarboxylase inhibitor; STEF: simple test for evaluating hand function; TUG: timed up and go test; TMT: trail-making test; SN: substantia nigra; NM-MRI: neuromelanin magnetic resonance imaging; MCID: the minimal clinically important difference; SNpc: substantia nigra pars compacta; VTA: ventral tegmental area; LC: locus coeruleus; PFC: prefrontal cortex; M1: primary motor cortex; MDS: Movement Disorder Society; MIBG: 123I-metaiodobenzylguanidine; SBR: specific binding ratio; SPECT: single-photon emission computed tomography; DAT: dopamine transporter; NIBS: noninvasive brain stimulation; tDCS: transcranial direct current stimulation; MAOB: monoamine oxidase B; DCI: decarboxylase inhibitor; repetitive transcranial magnetic stimulation: rTMS; diffusion tensor imaging: DTI; arterial spin labeling: ASL.

Intranasal delivery of exosomes from human adipose derived stem cells at forty-eight hours post injury reduces motor and cognitive impairments following traumatic brain injury.

The neuroprotective role of human adipose-derived stems cells (hASCs) has raised great interest in regenerative medicine due to their ability to modulate their surrounding environment. Our group has demonstrated that exosomes derived from hASC (hASCexo) are a cell-free regenerative approach to long term recovery following traumatic brain injury (TBI). Previously, we demonstrated the efficacy of exosome treatment with intravenous delivery at 3 h post TBI in rats. Here, we show efficacy of exosomes through intranasal delivery at 48 h post TBI in mice lengthening the therapeutic window of treatment and therefore increasing possible translation to clinical studies. Our findings demonstrate significant recovery of motor impairment assessed by an elevated body swing test in mice treated with exosomes containing MALAT1 compared to both TBI mice without exosomes and exosomes depleted of MALAT1. Significant cognitive improvement was seen in the reversal trial of 8 arm radial arm water maze in mice treated with exosomes containing MALAT1. Furthermore, cortical damage was significantly reduced in mice treated with exosomes containing MALAT1 as well as decreased MHCII+ staining of microglial cells. Mice without exosomes or treated with exosomes depleted of MALAT1 did not show similar recovery. Results demonstrate both inflammation related genes and NRTK3 (TrkC) are target genes modulated by hASC exosomes and further that MALAT1 in hASC exosomes regulates expression of full length TrkC thereby activating the MAPK pathway and promoting recovery. Exosomes are a promising therapeutic approach following TBI with a therapeutic window of at least 48 h and contain long noncoding RNA's, specifically MALAT1 that play a vital role in the mechanism of action.

Characterization of a Mouse Model of Alzheimer's Disease Expressing Aß4-42 and Human Mutant Tau.

The relationship between the two most prominent neuropathological hallmarks of Alzheimer's Disease (AD), extracellular amyloid-ß (Aß) deposits and intracellular accumulation of hyperphosphorylated tau in neurofibrillary tangles (NFT), remains at present not fully understood. A large body of evidence places Aß upstream in the cascade of pathological events, triggering NFTs formation and the subsequent neuron loss. Extracellular Aß deposits were indeed causative of an increased tau phosphorylation and accumulation in several transgenic models but the contribution of soluble Aß peptides is still controversial. Among the different Aß variants, the N-terminally truncated peptide Aß4-42 is among the most abundant. To understand whether soluble Aß4-42 peptides impact the onset or extent of tau pathology, we have crossed the homozygous Tg4-42 mouse model of AD, exclusively expressing Aß4-42 peptides, with the PS19 (P301S) tau transgenic model. Behavioral assessment showed that the resulting double-transgenic line presented a partial worsening of motor performance and spatial memory deficits in the aged group. While an increased loss of distal CA1 pyramidal neurons was detected in young mice, no significant alterations in hippocampal tau phosphorylation were observed in immunohistochemical analyses.

Tau mis-splicing correlates with motor impairments and striatal dysfunction in a model of tauopathy.

Tauopathies are neurodegenerative diseases caused by the abnormal metabolism of the microtubule associated protein tau (MAPT), which is highly expressed in neurons and critically involved in microtubule dynamics. In the adult human brain, the alternative splicing of exon 10 in MAPT pre-mRNA produces equal amounts of protein isoforms with either three (3R) or four (4R) microtubule binding domains. Imbalance in the 3R:4R tau ratio is associated with primary tauopathies that develop atypical parkinsonism, such as progressive supranuclear palsy and corticobasal degeneration. Yet, the development of effective therapies for those pathologies is an unmet goal. Here we report motor coordination impairments in the htau mouse model of tauopathy which harbour abnormal 3R:4R tau isoforms content, and in contrast to TauKO mice, are unresponsive to l-DOPA. Preclinical-PET imaging, array tomography and electrophysiological analyses indicated the dorsal striatum as the candidate structure mediating such phenotypes. Indeed, local modulation of tau isoforms by RNA trans-splicing in the striata of adult htau mice, prevented motor coordination deficits and restored basal neuronal firing. Together, these results suggest that abnormal striatal tau isoform content might lead to parkinsonian-like phenotypes and demonstrate a proof of concept that modulation of tau mis-splicing is a plausible disease-modifying therapy for some primary tauopathies.

Gain of toxic function by long-term AAV9-mediated SMN overexpression in the sensorimotor circuit.

The neurodegenerative disease spinal muscular atrophy (SMA) is caused by deficiency in the survival motor neuron (SMN) protein. Currently approved SMA treatments aim to restore SMN, but the potential for SMN expression beyond physiological levels is a unique feature of adeno-associated virus serotype 9 (AAV9)-SMN gene therapy. Here, we show that long-term AAV9-mediated SMN overexpression in mouse models induces dose-dependent, late-onset motor dysfunction associated with loss of proprioceptive synapses and neurodegeneration. Mechanistically, aggregation of overexpressed SMN in the cytoplasm of motor circuit neurons sequesters components of small nuclear ribonucleoproteins, leading to splicing dysregulation and widespread transcriptome abnormalities with prominent signatures of neuroinflammation and the innate immune response. Thus, long-term SMN overexpression interferes with RNA regulation and triggers SMA-like pathogenic events through toxic gain-of-function mechanisms. These unanticipated, SMN-dependent and neuron-specific liabilities warrant caution on the long-term safety of treating individuals with SMA with AAV9-SMN and the risks of uncontrolled protein expression by gene therapy.

Alteration of the cholinergic system and motor deficits in cholinergic neuron-specific Dyt1 knockout mice.

Dystonia is a neurological movement disorder characterized by sustained or intermittent muscle contractions, repetitive movement, and sometimes abnormal postures. DYT1 dystonia is one of the most common genetic dystonias, and most patients carry heterozygous DYT1 ∆GAG mutations causing a loss of a glutamic acid of the protein torsinA. Patients can be treated with anticholinergics, such as trihexyphenidyl, suggesting an abnormal cholinergic state. Early work on the cell-autonomous effects of Dyt1 deletion with ChI-specific Dyt1 conditional knockout mice (Dyt1 Ch1KO) revealed abnormal electrophysiological responses of striatal ChIs to muscarine and quinpirole, motor deficits, and no changes in the number or size of the ChIs. However, the Chat-cre line that was used to derive Dyt1 Ch1KO mice contained a neomycin cassette and was reported to have ectopic cre-mediated recombination. In this study, we generated a Dyt1 Ch2KO mouse line by removing the neomycin cassette in Dyt1 Ch1KO mice. The Dyt1 Ch2KO mice showed abnormal paw clenching behavior, motor coordination and balance deficits, impaired motor learning, reduced striatal choline acetyltransferase protein level, and a reduced number of striatal ChIs. Furthermore, the mutant striatal ChIs had a normal muscarinic inhibitory function, impaired quinpirole-mediated inhibition, and altered current density. Our findings demonstrate a cell-autonomous effect of Dyt1 deletion on the striatal ChIs and a critical role for the striatal ChIs and corticostriatal pathway in the pathogenesis of DYT1 dystonia.