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1.
Neurologia (Engl Ed) ; 39(5): 408-416, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38830720

ABSTRACT

Ataxias are characterized by aberrant movement patterns closely related to cerebellar dysfunction. Purkinje cell axons are the sole outputs from the cerebellar cortex, and dysfunctional activity of Purkinje cells has been associated with ataxic movements. However, the synaptic characteristics of Purkinje cells in cases of ataxia are not yet well understood. The nicotinamide antagonist 3-acethylpyridine (3-AP) selectively destroys inferior olivary nucleus neurons so it is widely used to induce cerebellar ataxia. Five days after 3-AP treatment (65mg/kg) in adult male Sprague-Dawley rats, motor incoordination was revealed through BBB and Rotarod testing. In addition, in Purkinje cells from lobules V-VII of the cerebellar vermis studied by the Golgi method, the density of dendritic spines decreased, especially the thin and mushroom types. Western blot analysis showed a decrease in AMPA and PSD-95 content with an increase of the α-catenin protein, while GAD-67 and synaptophysin were unchanged. Findings suggest a limited capacity of Purkinje cells to acquire and consolidate afferent excitatory inputs and an aberrant, rigid profile in the movement-related output patterns of Purkinje neurons that likely contributes to the motor-related impairments characteristic of cerebellar ataxias.


Subject(s)
Cerebellum , Purkinje Cells , Rats, Sprague-Dawley , Animals , Purkinje Cells/drug effects , Purkinje Cells/pathology , Male , Rats , Cerebellum/drug effects , Cerebellar Ataxia/chemically induced , Pyridines/pharmacology , Neuronal Plasticity/drug effects
2.
Cereb Cortex ; 34(13): 94-103, 2024 May 02.
Article in English | MEDLINE | ID: mdl-38696597

ABSTRACT

Autism (or autism spectrum disorder) was initially defined as a psychiatric disorder, with the likely cause maternal behavior (the very destructive "refrigerator mother" theory). It took several decades for research into brain mechanisms to become established. Both neuropathological and imaging studies found differences in the cerebellum in autism spectrum disorder, the most widely documented being a decreased density of Purkinje cells in the cerebellar cortex. The popular interpretation of these results is that cerebellar neuropathology is a critical cause of autism spectrum disorder. We challenge that view by arguing that if fewer Purkinje cells are critical for autism spectrum disorder, then any condition that causes the loss of Purkinje cells should also cause autism spectrum disorder. We will review data on damage to the cerebellum from cerebellar lesions, tumors, and several syndromes (Joubert syndrome, Fragile X, and tuberous sclerosis). Collectively, these studies raise the question of whether the cerebellum really has a role in autism spectrum disorder. Autism spectrum disorder is now recognized as a genetically caused developmental disorder. A better understanding of the genes that underlie the differences in brain development that result in autism spectrum disorder is likely to show that these genes affect the development of the cerebellum in parallel with the development of the structures that do underlie autism spectrum disorder.


Subject(s)
Cerebellum , Humans , Cerebellum/pathology , Autism Spectrum Disorder/pathology , Autism Spectrum Disorder/genetics , Autism Spectrum Disorder/physiopathology , Autism Spectrum Disorder/diagnostic imaging , Animals , Autistic Disorder/pathology , Autistic Disorder/genetics , Autistic Disorder/physiopathology , Purkinje Cells/pathology
3.
Neurobiol Dis ; 197: 106530, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38750673

ABSTRACT

Heterogeneity is one of the key features of the healthy brain and selective vulnerability characterizes many, if not all, neurodegenerative diseases. While cerebellum contains majority of brain cells, neither its heterogeneity nor selective vulnerability in disease are well understood. Here we describe molecular, cellular and functional heterogeneity in the context of healthy cerebellum as well as in cerebellar disease Spinocerebellar Ataxia Type 1 (SCA1). We first compared disease pathology in cerebellar vermis and hemispheres across anterior to posterior axis in a knock-in SCA1 mouse model. Using immunohistochemistry, we demonstrated earlier and more severe pathology of PCs and glia in the posterior cerebellar vermis of SCA1 mice. We also demonstrate heterogeneity of Bergmann glia in the unaffected, wild-type mice. Then, using RNA sequencing, we found both shared, as well as, posterior cerebellum-specific molecular mechanisms of pathogenesis that include exacerbated gene dysregulation, increased number of altered signaling pathways, and decreased pathway activity scores in the posterior cerebellum of SCA1 mice. We demonstrated unexpectedly large differences in the gene expression between posterior and anterior cerebellar vermis of wild-type mice, indicative of robust intraregional heterogeneity of gene expression in the healthy cerebellum. Additionally, we found that SCA1 disease profoundly reduces intracerebellar heterogeneity of gene expression. Further, using fiber photometry, we found that population level PC calcium activity was altered in the posterior lobules in SCA1 mice during walking. We also identified regional differences in the population level activity of Purkinje cells (PCs) in unrestrained wild-type mice that were diminished in SCA1 mice.


Subject(s)
Cerebellum , Spinocerebellar Ataxias , Animals , Cerebellum/metabolism , Cerebellum/pathology , Spinocerebellar Ataxias/pathology , Spinocerebellar Ataxias/metabolism , Spinocerebellar Ataxias/genetics , Mice , Ataxin-1/metabolism , Ataxin-1/genetics , Purkinje Cells/pathology , Purkinje Cells/metabolism , Neuroglia/metabolism , Neuroglia/pathology , Disease Models, Animal , Mice, Transgenic , Mice, Inbred C57BL , Male
4.
Zhonghua Bing Li Xue Za Zhi ; 53(5): 452-457, 2024 May 08.
Article in Chinese | MEDLINE | ID: mdl-38678325

ABSTRACT

Objective: To investigate the role of RNA m6A methylation in mediating cerebellar dysplasia through analyzing the phenotypes of the mouse cerebella and the expression of several key m6A regulators upon hypobaric hypoxia treatment. Methods: Five-day old C57/BL6 mice were exposed to hypobaric hypoxia for 9 days. The status of mouse cerebellar development was analyzed by comparing the body weights, brain weights and histological features. Immunostaining of cell-type-specific markers was performed to analyze the cerebellar morphology. Real-time PCR, Western blot and immunohistochemical staining were performed to detect the expression of key m6A regulators in the mouse cerebella. Results: Compared with the control, the body weights, brain weights and cerebellar volumes of hypobaric hypoxic mice were significantly reduced (P<0.01). The expression of specific markers in different cells, including NeuN (mature neuron), Calbindin-D28K (Purkinje cell) and GFAP (astrocyte), was decreased in hypobaric hypoxic mouse cerebella (P<0.01), accompanied with disorganized cellular structure. The expression of methyltransferase METTL3 was significantly down-regulated in the cerebella of hypobaric hypoxic mice (P<0.05). Conclusions: Hypobaric hypoxia stimulation causes mouse cerebellar dysplasia, with structural abnormalities in mature granular neurons, Purkinje cells and astrocytes. Expression of METTL3 is decreased in hypobaric hypoxic mice cerebellum compared with that of normobaric normoxic mice, suggesting that its mediated RNA m6A methylation may play an important role in hypobaric hypoxia-induced mouse cerebellar dysplasia.


Subject(s)
Calbindins , Cerebellum , DNA-Binding Proteins , Hypoxia , Methyltransferases , Mice, Inbred C57BL , Nerve Tissue Proteins , Purkinje Cells , Animals , Mice , Cerebellum/metabolism , Hypoxia/metabolism , Nerve Tissue Proteins/metabolism , Nerve Tissue Proteins/genetics , Purkinje Cells/metabolism , Purkinje Cells/pathology , Calbindins/metabolism , Calbindins/genetics , Methyltransferases/metabolism , Methyltransferases/genetics , Glial Fibrillary Acidic Protein/metabolism , Glial Fibrillary Acidic Protein/genetics , Astrocytes/metabolism , Down-Regulation , Methylation , Adenosine/metabolism , Adenosine/analogs & derivatives , Nervous System Malformations/metabolism , Nervous System Malformations/genetics
5.
Biomed Pharmacother ; 174: 116526, 2024 May.
Article in English | MEDLINE | ID: mdl-38574621

ABSTRACT

Spinocerebellar ataxia type 1 (SCA1) is a debilitating neurodegenerative disorder of the cerebellum and brainstem. Memantine has been proposed as a potential treatment for SCA1. It blocks N-methyl-D-aspartate (NMDA) receptors on neurons, reduces excitotoxicity and decreases neurodegeneration in Alzheimer models. However, in cerebellar neurodegenerative diseases, the potential value of memantine is still unclear. We investigated the effects of memantine on motor performance and synaptic transmission in the cerebellum in a mouse model where mutant ataxin 1 is specifically targeted to glia. Lentiviral vectors (LVV) were used to express mutant ataxin 1 selectively in Bergmann glia (BG). In mice transduced with the mutant ataxin 1, chronic treatment with memantine improved motor activity during initial tests, presumably due to preserved BG and Purkinje cell (PC) morphology and numbers. However, mice were unable to improve their rota rod scores during next days of training. Memantine also compromised improvement in the rota rod scores in control mice upon repetitive training. These effects may be due to the effects of memantine on plasticity (LTD suppression) and NMDA receptor modulation. Some effects of chronically administered memantine persisted even after its wash-out from brain slices. Chronic memantine reduced morphological signs of neurodegeneration in the cerebellum of SCA1 model mice. This resulted in an apparent initial reduction of ataxic phenotype, but memantine also affected cerebellar plasticity and ultimately compromised motor learning. We speculate that that clinical application of memantine in SCA1 might be hampered by its ability to suppress NMDA-dependent plasticity in cerebellar cortex.


Subject(s)
Disease Models, Animal , Memantine , Phenotype , Spinocerebellar Ataxias , Animals , Memantine/pharmacology , Spinocerebellar Ataxias/drug therapy , Spinocerebellar Ataxias/pathology , Mice , Ataxin-1/metabolism , Ataxin-1/genetics , Motor Activity/drug effects , Cerebellum/drug effects , Cerebellum/pathology , Cerebellum/metabolism , Purkinje Cells/drug effects , Purkinje Cells/pathology , Purkinje Cells/metabolism , Receptors, N-Methyl-D-Aspartate/metabolism , Mice, Transgenic , Mice, Inbred C57BL , Neuroglia/drug effects , Neuroglia/pathology , Neuroglia/metabolism , Male , Neuronal Plasticity/drug effects
6.
Neurobiol Dis ; 195: 106492, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38575093

ABSTRACT

We performed a comprehensive study of the morphological, functional, and genetic features of moonwalker (MWK) mice, a mouse model of spinocerebellar ataxia caused by a gain of function of the TRPC3 channel. These mice show numerous behavioral symptoms including tremor, altered gait, circling behavior, impaired motor coordination, impaired motor learning and decreased limb strength. Cerebellar pathology is characterized by early and almost complete loss of unipolar brush cells as well as slowly progressive, moderate loss of Purkinje cell (PCs). Structural damage also includes loss of synaptic contacts from parallel fibers, swollen ER structures, and degenerating axons. Interestingly, no obvious correlation was observed between PC loss and severity of the symptoms, as the phenotype stabilizes around 2 months of age, while the cerebellar pathology is progressive. This is probably due to the fact that PC function is severely impaired much earlier than the appearance of PC loss. Indeed, PC firing is already impaired in 3 weeks old mice. An interesting feature of the MWK pathology that still remains to be explained consists in a strong lobule selectivity of the PC loss, which is puzzling considering that TRPC is expressed in every PC. Intriguingly, genetic analysis of MWK cerebella shows, among other alterations, changes in the expression of both apoptosis inducing and resistance factors possibly suggesting that damaged PCs initiate specific cellular pathways that protect them from overt cell loss.


Subject(s)
Disease Models, Animal , Phenotype , Animals , Mice , Cerebellum/pathology , Cerebellum/metabolism , Purkinje Cells/pathology , Purkinje Cells/metabolism , TRPC Cation Channels/genetics , TRPC Cation Channels/metabolism , Genotype , Spinocerebellar Ataxias/pathology , Spinocerebellar Ataxias/genetics , Spinocerebellar Ataxias/metabolism , Mice, Neurologic Mutants , Mice, Inbred C57BL , Mice, Transgenic
7.
JCI Insight ; 9(10)2024 Apr 16.
Article in English | MEDLINE | ID: mdl-38625743

ABSTRACT

Dysregulated lipid homeostasis is emerging as a potential cause of neurodegenerative disorders. However, evidence of errors in lipid homeostasis as a pathogenic mechanism of neurodegeneration remains limited. Here, we show that cerebellar neurodegeneration caused by Sorting Nexin 14 (SNX14) deficiency is associated with lipid homeostasis defects. Recent studies indicate that SNX14 is an interorganelle lipid transfer protein that regulates lipid transport, lipid droplet (LD) biogenesis, and fatty acid desaturation, suggesting that human SNX14 deficiency belongs to an expanding class of cerebellar neurodegenerative disorders caused by altered cellular lipid homeostasis. To test this hypothesis, we generated a mouse model that recapitulates human SNX14 deficiency at a genetic and phenotypic level. We demonstrate that cerebellar Purkinje cells (PCs) are selectively vulnerable to SNX14 deficiency while forebrain regions preserve their neuronal content. Ultrastructure and lipidomic studies reveal widespread lipid storage and metabolism defects in SNX14-deficient mice. However, predegenerating SNX14-deficient cerebella show a unique accumulation of acylcarnitines and depletion of triglycerides. Furthermore, defects in LD content and telolysosome enlargement in predegenerating PCs suggest lipotoxicity as a pathogenic mechanism of SNX14 deficiency. Our work shows a selective cerebellar vulnerability to altered lipid homeostasis and provides a mouse model for future therapeutic studies.


Subject(s)
Homeostasis , Lipid Metabolism , Purkinje Cells , Sorting Nexins , Sorting Nexins/metabolism , Sorting Nexins/genetics , Animals , Mice , Humans , Purkinje Cells/metabolism , Purkinje Cells/pathology , Disease Models, Animal , Neurodegenerative Diseases/metabolism , Neurodegenerative Diseases/pathology , Neurodegenerative Diseases/genetics , Mice, Knockout , Cerebellum/metabolism , Cerebellum/pathology , Male , Lipid Droplets/metabolism
8.
Int J Mol Sci ; 25(8)2024 Apr 15.
Article in English | MEDLINE | ID: mdl-38673939

ABSTRACT

Polyglutamine (polyQ)-encoding CAG repeat expansions represent a common disease-causing mutation responsible for several dominant spinocerebellar ataxias (SCAs). PolyQ-expanded SCA proteins are toxic for cerebellar neurons, with Purkinje cells (PCs) being the most vulnerable. RNA interference (RNAi) reagents targeting transcripts with expanded CAG reduce the level of various mutant SCA proteins in an allele-selective manner in vitro and represent promising universal tools for treating multiple CAG/polyQ SCAs. However, it remains unclear whether the therapeutic targeting of CAG expansion can be achieved in vivo and if it can ameliorate cerebellar functions. Here, using a mouse model of SCA7 expressing a mutant Atxn7 allele with 140 CAGs, we examined the efficacy of short hairpin RNAs (shRNAs) targeting CAG repeats expressed from PHP.eB adeno-associated virus vectors (AAVs), which were introduced into the brain via intravascular injection. We demonstrated that shRNAs carrying various mismatches with the CAG target sequence reduced the level of polyQ-expanded ATXN7 in the cerebellum, albeit with varying degrees of allele selectivity and safety profile. An shRNA named A4 potently reduced the level of polyQ-expanded ATXN7, with no effect on normal ATXN7 levels and no adverse side effects. Furthermore, A4 shRNA treatment improved a range of motor and behavioral parameters 23 weeks after AAV injection and attenuated the disease burden of PCs by preventing the downregulation of several PC-type-specific genes. Our results show the feasibility of the selective targeting of CAG expansion in the cerebellum using a blood-brain barrier-permeable vector to attenuate the disease phenotype in an SCA mouse model. Our study represents a significant advancement in developing CAG-targeting strategies as a potential therapy for SCA7 and possibly other CAG/polyQ SCAs.


Subject(s)
Ataxin-7 , Dependovirus , Disease Models, Animal , Peptides , Phenotype , RNA, Small Interfering , Spinocerebellar Ataxias , Trinucleotide Repeat Expansion , Animals , Spinocerebellar Ataxias/genetics , Spinocerebellar Ataxias/therapy , Spinocerebellar Ataxias/metabolism , Peptides/genetics , Dependovirus/genetics , Mice , Ataxin-7/genetics , Ataxin-7/metabolism , Trinucleotide Repeat Expansion/genetics , RNA, Small Interfering/genetics , Genetic Vectors/genetics , Genetic Vectors/administration & dosage , Purkinje Cells/metabolism , Purkinje Cells/pathology , Mice, Transgenic , Cerebellum/metabolism , Cerebellum/pathology , Humans , Genetic Therapy/methods , Alleles
9.
Handb Clin Neurol ; 200: 409-417, 2024.
Article in English | MEDLINE | ID: mdl-38494293

ABSTRACT

Gynecologic and breast malignancies are the cancers most commonly associated with paraneoplastic neurologic syndromes, of which the foremost is Yo [Purkinje cell antibody, type 1 (PCA-1)] paraneoplastic cerebellar degeneration. Yo syndrome affects women in the sixth decade and manifests as a subacute severe cerebellar ataxia. The association of the typical clinical picture with the detection of Yo antibodies in a patient's serum or CSF defines the diagnosis. Yo syndrome is always associated with a cancer, and the search for the underlying tumor should focus on ovarian and breast cancers and be repeated overtime if negative. The Yo autoantibodies are directed against the Yo antigens, aberrantly overexpressed by tumor cells with frequent somatic mutations and gene amplifications. The massive infiltration of these tumors by immune cells suggests that they are the site of the immune tolerance breakdown, leading to the destruction of Purkinje cells harboring the Yo antigens. Despite a growing understanding of the immunologic mechanisms, efficient therapeutic options are still lacking. Anti-Ri and antiamphiphysin syndromes are rarer and associated with breast cancers; a wide variety of other rare paraneoplastic neurologic syndromes have been described in association with gynecologic and breast malignancies that, though sharing some similarities, may have specific immune and genetics features leading to the immune tolerance breakdown.


Subject(s)
Breast Neoplasms , Paraneoplastic Cerebellar Degeneration , Female , Humans , Breast Neoplasms/complications , Paraneoplastic Cerebellar Degeneration/etiology , Paraneoplastic Cerebellar Degeneration/diagnosis , Autoantibodies , Purkinje Cells/pathology
10.
J Neuroinflammation ; 21(1): 49, 2024 Feb 14.
Article in English | MEDLINE | ID: mdl-38355633

ABSTRACT

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) constitute a recently discovered bone-marrow-derived cell type useful for dealing with neuroinflammatory disorders. However, these cells are only formed during inflammatory conditions from immature myeloid cells (IMCs) that acquire immunosuppressive activity, thus being commonly gathered from diseased animals. Then, to obtain a more clinically feasible source, we characterized IMCs directly derived from healthy bone marrow and proved their potential immunosuppressive activity under pathological conditions in vitro. We then explored their neuroprotective potential in a model of human cerebellar ataxia, the Purkinje Cell Degeneration (PCD) mouse, as it displays a well-defined neurodegenerative and neuroinflammatory process that can be also aggravated by invasive surgeries. METHODS: IMCs were obtained from healthy bone marrow and co-cultured with activated T cells. The proliferation and apoptotic rate of the later were analyzed with Tag-it Violet. For in vivo studies, IMCs were transplanted by stereotactic surgery into the cerebellum of PCD mice. We also used sham-operated animals as controls of the surgical effects, as well as their untreated counterparts. Motor behavior of mice was assessed by rotarod test. The Purkinje cell density was measured by immunohistochemistry and cell death assessed with the TUNEL technique. We also analyzed the microglial phenotype by immunofluorescence and the expression pattern of inflammation-related genes by qPCR. Parametric tests were applied depending on the specific experiment: one or two way ANOVA and Student's T test. RESULTS: IMCs were proven to effectively acquire immunosuppressive activity under pathological conditions in vitro, thus acting as MDSCs. Concerning in vivo studios, sham-operated PCD mice suffered detrimental effects in motor coordination, Purkinje cell survival and microglial activation. After intracranial administration of IMCs into the cerebellum of PCD mice, no special benefits were detected in the transplanted animals when compared to untreated mice. Nonetheless, this transplant almost completely prevented the impairments caused by the surgery in PCD mice, probably by the modulation of the inflammatory patterns. CONCLUSIONS: Our work comprise two main translational findings: (1) IMCs can be directly used as they behave as MDSCs under pathological conditions, thus avoiding their gathering from diseased subjects; (2) IMCs are promising adjuvants when performing neurosurgery.


Subject(s)
Cerebellum , Myeloid Cells , Mice , Humans , Animals , Myeloid Cells/metabolism , Purkinje Cells/pathology , Monocytes , Immunosuppressive Agents
11.
J Chem Neuroanat ; 137: 102399, 2024 04.
Article in English | MEDLINE | ID: mdl-38401660

ABSTRACT

Cerebellar ataxia (CA) is a condition in which cerebellar dysfunction results in movement disorders such as dysmetria, synergy and dysdiadochokinesia. This study investigates the therapeutic effects of elderberry (EB) diet on the 3-acetylpyridine-induced (3-AP) CA rat model. First, CA rat models were generated by 3-AP administration followed by elderberry diet treatment containing 2 % EB for 8 consecutive weeks. Motor performance, electromyographic activity and gene expression were then evaluated. The number of Purkinje neurons were evaluated by stereological methods. Immunohistochemistry for the microgliosis, astrogliosis and apoptosis marker caspase-3 was also performed. In addition, the morphology of microglia and astrocytes was assessed using the Sholl analysis method. The results showed that EB diet administration in a 3-AP ataxia model improved motor coordination, locomotor activity and neuro-muscular function, prevented Purkinje neurons degeneration, increased microglia and astrocyte complexity and reduced cell soma size. Moreover, EB diet administration decreased apoptosis in cerebellum of 3-AP ataxic model. In addition, elderberry diet treatment decreased the expression of inflammatory, apoptotic and necroptotic genes and increased the expression of antioxidant-related genes. The results suggest that the EB diet attenuates 3-AP-induced neuroinflammation leading to cell death and improves motor performance. Thus, the EB diet could be used as a therapeutic procedure for CA due to its neuroprotective effects.


Subject(s)
Cerebellar Ataxia , Disease Models, Animal , Pyridines , Animals , Rats , Cerebellar Ataxia/pathology , Cerebellar Ataxia/metabolism , Male , Cell Death , Neuroinflammatory Diseases/pathology , Neuroinflammatory Diseases/metabolism , Purkinje Cells/pathology , Purkinje Cells/metabolism , Motor Activity/physiology , Diet , Rats, Wistar , Microglia/metabolism , Microglia/pathology , Cerebellum/pathology , Cerebellum/metabolism
12.
PLoS One ; 18(11): e0294312, 2023.
Article in English | MEDLINE | ID: mdl-38033125

ABSTRACT

Lysosomes play important roles in catabolism, nutrient sensing, metabolic signaling, and homeostasis. NPC1 deficiency disrupts lysosomal function by inducing cholesterol accumulation that leads to early neurodegeneration in Niemann-Pick type C (NPC) disease. Mitochondria pathology and deficits in NPC1 deficient cells are associated with impaired lysosomal proteolysis and metabolic signaling. It is thought that activation of the transcription factor TFEB, an inducer of lysosome biogenesis, restores lysosomal-autophagy activity in lysosomal storage disorders. Here, we investigated the effect of trehalose, a TFEB activator, in the mitochondria pathology of NPC1 mutant fibroblasts in vitro and in mouse developmental Purkinje cells ex vivo. We found that in NPC1 mutant fibroblasts, serum starvation or/and trehalose treatment, both activators of TFEB, reversed mitochondria fragmentation to a more tubular mitochondrion. Trehalose treatment also decreased the accumulation of Filipin+ cholesterol in NPC1 mutant fibroblasts. However, trehalose treatment in cerebellar organotypic slices (COSCs) from wild-type and Npc1nmf164 mice caused mitochondria fragmentation and lack of dendritic growth and degeneration in developmental Purkinje cells. Our data suggest, that although trehalose successfully restores mitochondria length and decreases cholesterol accumulation in NPC1 mutant fibroblasts, in COSCs, Purkinje cells mitochondria and dendritic growth are negatively affected possibly through the overactivation of the TFEB-lysosomal-autophagy pathway.


Subject(s)
Mitochondria , Niemann-Pick Disease, Type C , Trehalose , Animals , Humans , Mice , Cholesterol/metabolism , Fibroblasts/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Lysosomes/metabolism , Mitochondria/metabolism , Niemann-Pick C1 Protein , Niemann-Pick Disease, Type C/drug therapy , Niemann-Pick Disease, Type C/genetics , Niemann-Pick Disease, Type C/metabolism , Purkinje Cells/pathology , Trehalose/pharmacology
13.
Neurobiol Dis ; 187: 106318, 2023 Oct 15.
Article in English | MEDLINE | ID: mdl-37802154

ABSTRACT

Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disease caused by an abnormal expansion of glutamine (Q) encoding CAG repeats in the ATAXIN1 (ATXN1) gene and characterized by progressive cerebellar ataxia, dysarthria, and eventual deterioration of bulbar functions. SCA1 shows severe degeneration of cerebellar Purkinje cells (PCs) and activation of Bergmann glia (BG), a type of cerebellar astroglia closely associated with PCs. Combining electrophysiological recordings, calcium imaging techniques, and chemogenetic approaches, we have investigated the electrical intrinsic and synaptic properties of PCs and the physiological properties of BG in SCA1 mouse model expressing mutant ATXN1 only in PCs. PCs of SCA1 mice displayed lower spontaneous firing rate and larger slow afterhyperpolarization currents (sIAHP) than wildtype mice, whereas the properties of the synaptic inputs were unaffected. BG of SCA1 mice showed higher calcium hyperactivity and gliotransmission, manifested by higher frequency of NMDAR-mediated slow inward currents (SICs) in PC. Preventing the BG calcium hyperexcitability of SCA1 mice by loading BG with the calcium chelator BAPTA restored sIAHP and spontaneous firing rate of PCs to similar levels of wildtype mice. Moreover, mimicking the BG hyperactivity by activating BG expressing Gq-DREADDs in wildtype mice reproduced the SCA1 pathological phenotype of PCs, i.e., enhancement of sIAHP and decrease of spontaneous firing rate. These results indicate that the intrinsic electrical properties of PCs, but not their synaptic properties, were altered in SCA1 mice and that these alterations were associated with the hyperexcitability of BG. Moreover, preventing BG hyperexcitability in SCA1 mice and promoting BG hyperexcitability in wildtype mice prevented and mimicked, respectively, the pathological electrophysiological phenotype of PCs. Therefore, BG plays a relevant role in the dysfunction of the electrical intrinsic properties of PCs in SCA1 mice, suggesting that they may serve as potential targets for therapeutic approaches to treat the spinocerebellar ataxia type 1.


Subject(s)
Calcium , Spinocerebellar Ataxias , Mice , Animals , Calcium/physiology , Calcium Signaling , Mice, Transgenic , Spinocerebellar Ataxias/genetics , Spinocerebellar Ataxias/pathology , Cerebellum/pathology , Purkinje Cells/pathology , Neuroglia/pathology , Ataxin-1/genetics
14.
Cells ; 12(10)2023 05 13.
Article in English | MEDLINE | ID: mdl-37408217

ABSTRACT

Dominantly inherited missense mutations of the KCNA1 gene, which encodes the KV1.1 potassium channel subunit, cause Episodic Ataxia type 1 (EA1). Although the cerebellar incoordination is thought to arise from abnormal Purkinje cell output, the underlying functional deficit remains unclear. Here we examine synaptic and non-synaptic inhibition of Purkinje cells by cerebellar basket cells in an adult mouse model of EA1. The synaptic function of basket cell terminals was unaffected, despite their intense enrichment for KV1.1-containing channels. In turn, the phase response curve quantifying the influence of basket cell input on Purkine cell output was maintained. However, ultra-fast non-synaptic ephaptic coupling, which occurs in the cerebellar 'pinceau' formation surrounding the axon initial segment of Purkinje cells, was profoundly reduced in EA1 mice in comparison with their wild type littermates. The altered temporal profile of basket cell inhibition of Purkinje cells underlines the importance of Kv1.1 channels for this form of signalling, and may contribute to the clinical phenotype of EA1.


Subject(s)
Ataxia , Kv1.1 Potassium Channel , Myokymia , Neural Inhibition , Purkinje Cells , Purkinje Cells/metabolism , Purkinje Cells/pathology , Animals , Mice , Disease Models, Animal , Kv1.1 Potassium Channel/genetics , Kv1.1 Potassium Channel/metabolism , Synapses/physiology , Cell Communication , Synaptic Transmission , Ataxia/genetics , Ataxia/pathology , Ataxia/physiopathology , Myokymia/genetics , Myokymia/pathology , Myokymia/physiopathology , Evoked Potentials , Mice, Inbred C57BL , Male , Female
15.
Int J Mol Sci ; 24(11)2023 Jun 02.
Article in English | MEDLINE | ID: mdl-37298649

ABSTRACT

Mitochondrial diseases represent the most common inherited neurometabolic disorders, for which no effective therapy currently exists for most patients. The unmet clinical need requires a more comprehensive understanding of the disease mechanisms and the development of reliable and robust in vivo models that accurately recapitulate human disease. This review aims to summarise and discuss various mouse models harbouring transgenic impairments in genes that regulate mitochondrial function, specifically their neurological phenotype and neuropathological features. Ataxia secondary to cerebellar impairment is one of the most prevalent neurological features of mouse models of mitochondrial dysfunction, consistent with the observation that progressive cerebellar ataxia is a common neurological manifestation in patients with mitochondrial disease. The loss of Purkinje neurons is a shared neuropathological finding in human post-mortem tissues and numerous mouse models. However, none of the existing mouse models recapitulate other devastating neurological phenotypes, such as refractory focal seizures and stroke-like episodes seen in patients. Additionally, we discuss the roles of reactive astrogliosis and microglial reactivity, which may be driving the neuropathology in some of the mouse models of mitochondrial dysfunction, as well as mechanisms through which cellular death may occur, beyond apoptosis, in neurons undergoing mitochondrial bioenergy crisis.


Subject(s)
Cerebellar Ataxia , Mitochondrial Diseases , Mice , Animals , Humans , Ataxia/genetics , Cerebellar Ataxia/pathology , Purkinje Cells/pathology , Mitochondrial Diseases/genetics , Mitochondrial Diseases/pathology , Seizures/pathology , Phenotype , Disease Models, Animal
16.
J Vet Intern Med ; 37(4): 1568-1579, 2023.
Article in English | MEDLINE | ID: mdl-37288990

ABSTRACT

BACKGROUND: Shivers in horses is characterized by abnormal hindlimb movement when walking backward and is proposed to be caused by a Purkinje cell (PC) axonopathy based on histopathology. OBJECTIVES: Define region-specific differences in gene expression within the lateral cerebellar hemisphere and compare cerebellar protein expression between Shivers horses and controls. ANIMALS: Case-control study of 5 Shivers and 4 control geldings ≥16.2 hands in height. METHODS: Using spatial transcriptomics, gene expression was compared between Shivers and control horses in PC soma and lateral cerebellar hemisphere white matter, consisting primarily of axons. Tandem-mass-tag (TMT-11) proteomic analysis was performed on lateral cerebellar hemisphere homogenates. RESULTS: Differences in gene expression between Shivers and control horses were evident in principal component analysis of axon-containing white matter but not PC soma. In white matter, there were 455/1846 differentially expressed genes (DEG; 350 ↓DEG, 105 ↑DEG) between Shivers and controls, with significant gene set enrichment of the Toll-Like Receptor 4 (TLR4) cascade, highlighting neuroinflammation. There were 50/936 differentially expressed proteins (DEP). The 27 ↓DEP highlighted loss of axonal proteins including intermediate filaments (5), myelin (3), cytoskeleton (2), neurite outgrowth (2), and Na/K ATPase (1). The 23 ↑DEP were involved in the extracellular matrix (7), cytoskeleton (7), redox balance (2), neurite outgrowth (1), signal transduction (1), and others. CONCLUSION AND CLINICAL IMPORTANCE: Our findings support axonal degeneration as a characteristic feature of Shivers. Combined with histopathology, these findings are consistent with the known distinctive response of PC to injury where axonal changes occur without a substantial impact on PC soma.


Subject(s)
Proteomics , Transcriptome , Male , Animals , Horses , Case-Control Studies , Purkinje Cells/pathology , Axons/pathology
17.
Mov Disord ; 38(8): 1428-1442, 2023 08.
Article in English | MEDLINE | ID: mdl-37278528

ABSTRACT

BACKGROUND: Spinocerebellar ataxia type 1 (SCA1) is a neurodegenerative disease caused by a polyglutamine expansion in the ataxin-1 protein resulting in neuropathology including mutant ataxin-1 protein aggregation, aberrant neurodevelopment, and mitochondrial dysfunction. OBJECTIVES: Identify SCA1-relevant phenotypes in patient-specific fibroblasts and SCA1 induced pluripotent stem cells (iPSCs) neuronal cultures. METHODS: SCA1 iPSCs were generated and differentiated into neuronal cultures. Protein aggregation and neuronal morphology were evaluated using fluorescent microscopy. Mitochondrial respiration was measured using the Seahorse Analyzer. The multi-electrode array (MEA) was used to identify network activity. Finally, gene expression changes were studied using RNA-seq to identify disease-specific mechanisms. RESULTS: Bioenergetics deficits in patient-derived fibroblasts and SCA1 neuronal cultures showed altered oxygen consumption rate, suggesting involvement of mitochondrial dysfunction in SCA1. In SCA1 hiPSC-derived neuronal cells, nuclear and cytoplasmic aggregates were identified similar in localization as aggregates in SCA1 postmortem brain tissue. SCA1 hiPSC-derived neuronal cells showed reduced dendrite length and number of branching points while MEA recordings identified delayed development in network activity in SCA1 hiPSC-derived neuronal cells. Transcriptome analysis identified 1050 differentially expressed genes in SCA1 hiPSC-derived neuronal cells associated with synapse organization and neuron projection guidance, where a subgroup of 151 genes was highly associated with SCA1 phenotypes and linked to SCA1 relevant signaling pathways. CONCLUSIONS: Patient-derived cells recapitulate key pathological features of SCA1 pathogenesis providing a valuable tool for the identification of novel disease-specific processes. This model can be used for high throughput screenings to identify compounds, which may prevent or rescue neurodegeneration in this devastating disease. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.


Subject(s)
Induced Pluripotent Stem Cells , Spinocerebellar Ataxias , Mice , Animals , Ataxins/metabolism , Protein Aggregates , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Nuclear Proteins/genetics , Mice, Transgenic , Purkinje Cells/metabolism , Purkinje Cells/pathology , Spinocerebellar Ataxias/metabolism , Fibroblasts/metabolism
18.
Life Sci Alliance ; 6(9)2023 09.
Article in English | MEDLINE | ID: mdl-37369603

ABSTRACT

Niemann-Pick disease type C1 (NPC1) is a fatal lysosomal storage disorder characterized by progressive neuronal degeneration. Its key pathogenic events remain largely unknown. We have, herein, found that neonatal BM-derived cell transplantation can ameliorate Purkinje cell degeneration in NPC1 mice. We subsequently addressed the impact of the peripheral immune system on the neuropathogenesis observed in NPC1 mice. The depletion of mature lymphocytes promoted NPC1 phenotypes, thereby suggesting a neuroprotective effect of lymphocytes. Moreover, the peripheral infusion of CD4-positive cells (specifically, of regulatory T cells) from normal healthy donor ameliorated the cerebellar ataxic phenotype and enhanced the survival of Purkinje cells. Conversely, the depletion of regulatory T cells enhanced the onset of the neurological phenotype. On the other hand, circulating inflammatory monocytes were found to be involved in the progression of Purkinje cell degeneration, whereas the depletion of resident microglia had little effect. Our findings reveal a novel role of the adaptive and the innate immune systems in NPC1 neuropathology.


Subject(s)
Niemann-Pick Disease, Type C , Purkinje Cells , Mice , Animals , Purkinje Cells/metabolism , Purkinje Cells/pathology , Niemann-Pick Disease, Type C/genetics , Cerebellum/metabolism , Immune System/metabolism , Microglia/metabolism
19.
Biomolecules ; 13(5)2023 05 02.
Article in English | MEDLINE | ID: mdl-37238658

ABSTRACT

Spinocerebellar ataxia type 1 (SCA1) is an autosomal dominant neurodegenerative disorder that affects one or two individuals per 100,000. The disease is caused by an extended CAG repeat in exon 8 of the ATXN1 gene and is characterized mostly by a profound loss of cerebellar Purkinje cells, leading to disturbances in coordination, balance, and gait. At present, no curative treatment is available for SCA1. However, increasing knowledge on the cellular and molecular mechanisms of SCA1 has led the way towards several therapeutic strategies that can potentially slow disease progression. SCA1 therapeutics can be classified as genetic, pharmacological, and cell replacement therapies. These different therapeutic strategies target either the (mutant) ATXN1 RNA or the ataxin-1 protein, pathways that play an important role in downstream SCA1 disease mechanisms or which help restore cells that are lost due to SCA1 pathology. In this review, we will provide a summary of the different therapeutic strategies that are currently being investigated for SCA1.


Subject(s)
Cerebellum , Spinocerebellar Ataxias , Humans , Cerebellum/metabolism , Spinocerebellar Ataxias/genetics , Spinocerebellar Ataxias/therapy , Ataxin-1/genetics , Ataxin-1/metabolism , Purkinje Cells/pathology
20.
Neuroimage ; 276: 120198, 2023 08 01.
Article in English | MEDLINE | ID: mdl-37245561

ABSTRACT

Magnetic Resonance Imaging (MRI) resolution continues to improve, making it important to understand the cellular basis for different MRI contrast mechanisms. Manganese-enhanced MRI (MEMRI) produces layer-specific contrast throughout the brain enabling in vivo visualization of cellular cytoarchitecture, particularly in the cerebellum. Due to the unique geometry of the cerebellum, especially near the midline, 2D MEMRI images can be acquired from a relatively thick slice by averaging through areas of uniform morphology and cytoarchitecture to produce very high-resolution visualization of sagittal planes. In such images, MEMRI hyperintensity is uniform in thickness throughout the anterior-posterior axis of sagittal sections and is centrally located in the cerebellar cortex. These signal features suggested that the Purkinje cell layer, which houses the cell bodies of the Purkinje cells and the Bergmann glia, is the source of hyperintensity. Despite this circumstantial evidence, the cellular source of MRI contrast has been difficult to define. In this study, we quantified the effects of selective ablation of Purkinje cells or Bergmann glia on cerebellar MEMRI signal to determine whether signal could be assigned to one cell type. We found that the Purkinje cells, not the Bergmann glia, are the primary of source of the enhancement in the Purkinje cell layer. This cell-ablation strategy should be useful for determining the cell specificity of other MRI contrast mechanisms.


Subject(s)
Cerebellum , Manganese , Humans , Manganese/metabolism , Cerebellum/pathology , Purkinje Cells/metabolism , Purkinje Cells/pathology , Neuroglia/metabolism , Magnetic Resonance Imaging/methods
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