Biology subjects

Cvetanovic, M.

Publications and source records attributed to Cvetanovic, M..

10 recordsLinked to original sources

bioRxiv2026

Mutant ATXN1 impacts human and mouse microglia and contributes to cognitive, mood, and motor deficits in SCA1 mice

Microglia, resident immune cells of the brain, are important players in neurodegeneration. While microglial activation is a hallmark of many neurodegenerative diseases, the specific role of microglia intrinsic factors in microglial activation and disease pathogenesis remains unknown. Spinocerebellar ataxia type-1 (SCA1) is an inherited autosomal dominant neurodegenerative disease characterized by severe neuronal loss and early microglial activation in the cerebellum. SCA1 is caused by CAG repeat expansion in the ubiquitously expressed ATAXIN1 (ATXN1) gene. Using human microglia differentiated from SCA1 patient derived iPSCs, we found that mutant ATXN1 is sufficient to alter morphology, gene and protein expression in human microglia in a cell-autonomous manner. Moreover, compared to controls, human SCA1 microglia exhibited increased phagocytosis and pro-inflammatory cytokine production, indicating an immune priming. To determine the extent to which mutant ATXN1 in microglia contributes to SCA1 pathogenesis and behavioral symptoms, we removed mutant ATXN1 from microglia and macrophages in a novel conditional SCA1 mouse model, f-ATXN1146Q/2Q mice. Microglial mutant ATXN1 reduction led to a marked correction in microglia phenotype, in particular in the transcriptomic signature of interferon type 1 mediated immune response, reduced microglial density and resulted in smaller microglia with reduced branching in the cerebellum. Pathology of Purkinje neurons and cerebellar astrogliosis were also ameliorated. Utilizing a battery of behavioral tests, we found that microglia and macrophage mutant ATXN1 reduction ameliorated cognitive, mood, and motor deficits in SCA1 mice. Together, these results indicate that mutant ATXN1 directly impacts microglial phenotype in SCA1, contributing to SCA1 pathology and behavioral deficits.

neuroscience↗

bioRxiv2024

A neural basis for mutant ATAXIN-1 induced respiratory dysfunction in mouse models of Spinocerebellar ataxia type 1

Spinocerebellar ataxia type 1 (SCA1), a dominantly inherited neurodegenerative disorder caused by an expanded trinucleotide repeat in the ATAXIN-1 (ATXN1) gene, is characterized by motor dysfunction, cognitive impairment, and death from compromised swallowing and respiration. To delineate specific cell types that contribute to respiratory dysfunction, we utilized the floxed conditional knock-in f-ATXN1146Q/2Q mouse. Whole body plethysmography during spontaneous respiration and respiratory challenge showed that f-ATXN1146Q/2Q mice exhibit a spontaneous respiratory phenotype characterized by elevated respiratory frequency, volumes, and respiratory output. Consequently, the ability of f-ATXN1146Q/2Q mice to increase ventilation during the challenge is impaired. To investigate the role of mutant ATXN1 expression in neural and skeletal muscle lineages, f-ATXN1146Q/2Q mice were bred to Nestin-Cre and Acta1-Cre mice respectively. These analyses revealed that the abnormal spontaneous respiration in f-ATXN1146Q/2Q mice involved two aspects: a behavioral phenotype in which SCA1 mice exhibit increased motor activity during respiratory testing and functional dysregulation of central respiratory control centers. Both aspects of spontaneous respiration were partially ameliorated by removing mutant ATXN1 from neural, but not skeletal muscle, cell lineages.

neuroscience↗

bioRxiv2024

Cerebellar contribution to cognitive deficits and prefrontal cortex dysfunction in Spinocerebellar Ataxia Type 1 (SCA1)

The cerebellums role in cognition and its functional bi-directional connectivity with prefrontal cortex (PFC) is now recognized. However, how chronic cerebellar dysfunction affects PFC function and cognition remains less understood. Spinocerebellar ataxia type 1 (SCA1), is an inherited, fatal neurodegenerative disease caused by an abnormal expansion of glutamine (Q) encoding CAG repeats in the gene Ataxin-1 (ATXN1) and characterized by severe loss of Purkinje cells (PCs) in the cerebellum. Patients with SCA1 suffer from movement and balance deficits, cognitive decline and premature lethality. Cognitive deficits significantly impact patients quality of life, yet how exactly cerebellar degeneration contributes to cognitive deficits and PFC dysfunction in SCA1 is unknown. We have previously demonstrated that expression of mutant ATXN1 only in cerebellar Purkinje cells (PCs) is sufficient to cause cognitive deficits in a transgenic ATXN1[82Q] mouse line. To understand how cerebellar dysfunction impacts the PFC, we examined neuronal activity, synaptic density, and gene expression changes in the PFC of ATXN1[82Q] mice. Remarkably, we found decreased neuronal activity, reduced synaptic density, and altered expression of immediate early genes and pathways involved in glucose metabolism, inflammation and amphetamine in the PFC of ATXN1[82Q] mice. Furthermore, we characterized cellular and molecular PFC dysfunction in a novel conditional knock-in SCA1 line, f-ATXN1146Q mice, expressing floxed human expanded ATXN1 throughout the brain. Intriguingly, we found an increased number of neurons, increased synaptic density and large gene expression alterations in the PFC of f-ATXN1146Q mice. Finally, to precisely determine the role of cerebellar dysfunction in cognitive deficits and PFC dysfunction in SCA1, we crossed f-ATXN1146Q mice with Pcp2-Cre mice expressing Cre recombinase in PCs to delete expanded ATXN1 only in PCs. Surprisingly, we have found that deleting expanded ATXN1 in PCs exacerbated cognitive deficits and PFC dysfunction in these mice. Our findings demonstrate that circumscribed cerebellar dysfunction is sufficient to impact PFC activity and synaptic connectivity impairing cognition. However, when multiple brain regions are impacted in disease, cerebellar dysfunction may ameliorate PFC pathology and cognitive performance.

neuroscience↗

bioRxiv2023

Altered calcium signaling in Bergmann glia contributes to Spinocerebellar ataxia type-1

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. Using electrophysiological recordings, confocal imaging 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 medium and slow afterhyperpolarization currents (mIAHP and sIAHP) than wildtype mice, whereas the properties of the synaptic inputs were unaffected. BG of SCA1 mice showed higher calcium hyperactivity and gliotransmission, manifested 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 mIAHP and 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 mIAHP and 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.

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bioRxiv2023

Regional vulnerability in a neurodegenerative disease: Delineating SCA1 CNS and muscle therapeutic targets using a conditional mutant ATXN1 mouse

Spinocerebellar ataxia type 1 (SCA1) is a fatal neurodegenerative disease caused by an expanded polyglutamine tract in the widely expressed ATXN1 protein. To elucidate anatomical regions and cell types that underlie mutant ATXN1-induced disease phenotypes, we developed a floxed conditional knockout mouse model (f-ATXN1146Q/2Q) having mouse Atxn1 coding exons replaced by human exons encoding 146 glutamines. F-ATXN1146Q/2Q mice manifest SCA1-like phenotypes including motor and cognitive deficits, wasting, and decreased survival. CNS contributions to disease were revealed using ATXN1146Q/2Q;Nestin-Cre mice, that showed improved rotarod, open field and Barnes maze performances. Striatal contributions to motor deficits were examined using f-ATXN1146Q/2Q;Rgs9-Cre mice. Mice lacking striatal ATXN1146Q/2Q had improved rotarod performance late in disease. Muscle contributions to disease were revealed in f-ATXN1146Q/2Q;ACTA1-Cre mice which lacked muscle pathology and kyphosis seen in f-ATXN1146Q/2Q mice. Kyphosis was not improved in f-ATXN1146Q/2Q;Nestin-Cre mice. Thus, optimal SCA1 therapeutics will require targeting mutant ATXN1 toxic actions in multiple brain regions and muscle.

neuroscience↗

bioRxiv2022

Increased vulnerability of Purkinje cells in the posterior cerebellum of SCA1 mice is associated with molecular and cellular alterations related to disease pathology

Regional heterogeneity of neurons and glia is a key feature of the brain, yet the effect of disease on heterogeneity and its relationship with selective neuronal vulnerability remains poorly understood. Using region-specific RNA sequencing, we identified a large number of differentially expressed genes (DEGs) across distinct regions of the cerebellar cortex, supporting the notable intrinsic regional transcriptional heterogeneity of the healthy cerebellum. Further, we used fiber photometry to identify regional physiological differences in the activity of Purkinje cells (PCs) during self-motivated, unrestrained walking and non-walking states. In the inherited cerebellar neurodegenerative disease Spinocerebellar ataxia type 1 (SCA1), patients exhibit preferential degeneration of the posterior cerebellum, suggesting regionally selective vulnerability. We demonstrated that in a mouse model of SCA1 the Purkinje cells and glia residing in the posterior vermis of cerebellum also undergo earlier and more severe pathology. Intriguingly, the intrinsic transcriptional heterogeneity of anterior and posterior cerebellum seen in healthy mice was diminished in SCA1 mice. This disruption was also demonstrated via fiber photometry, where we found notable impacts in PC activity in the posterior cerebellum as well as loss of regional differences in PC activity during self-motivated, unrestrained walking, and non-walking states in SCA1 mice. Our findings indicate regionally distinct mechanisms of pathogenesis across cerebellar regions that result in reduced intracerebellar heterogeneity.

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bioRxiv2021

Disrupting ATXN1 Nuclear Localization in a Knock-in SCA1 Mouse Model Improves a Spectrum of SCA1-Like Phenotypes and their Brain Region Associated Transcriptomic Profiles

Spinocerebellar ataxia type 1 (SCA1) is a dominant trinucleotide repeat neurodegenerative disease characterized by motor dysfunction, cognitive impairment, and premature death. Degeneration of cerebellar Purkinje cells is a frequent and prominent pathological feature of SCA1. We previously showed that transport of ATXN1 to Purkinje cell nuclei is required for pathology, where mutant ATXN1 alters transcription. To examine the role of ATXN1 nuclear localization broadly in SCA1-like disease pathogenesis, CRISPR-Cas9 was used to develop a mouse with the amino acid alteration (K772T) in the nuclear localization sequence of the expanded ATXN1 protein. Characterization of these mice indicates proper nuclear localization of mutant ATXN1 contributes to many disease-like phenotypes including motor dysfunction, cognitive deficits, and premature lethality. RNA sequencing analysis of genes whose expression was corrected to WT levels in Atxn1175QK772T/2Q mice indicates that transcriptomic aspects of SCA1 pathogenesis differ between the cerebellum, brainstem, cerebral cortex, hippocampus, and striatum.

neuroscience↗

bioRxiv2021

Single-nuclei RNA sequencing uncovers non-cell autonomous changes in cerebellar astrocytes and oligodendrocytes that may contribute to Spinocerebellar Ataxia Type 1 (SCA1) pathogenesis

Glial cells, including astrocytes and oligodendrocytes are important for normal brain function. In many neurodegenerative diseases glial cells undergo significant morphological, functional and gene expression changes termed reactive gliosis. The cause, identity and neuroprotective or neurotoxic nature of these changes remains incompletely understood. This knowledge in needed to develop a framework of how individual pathological changes in glial cells contribute to progressive dysfunction and selective neuronal vulnerability in neurodegenerative diseases. This is particularly relevant during the early disease stages that allow for the effective therapies and reversal or slowing of disease phenotypes. Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease caused by an abnormal expansion of CAG repeats in the gene Ataxin1 (ATXN1). While mutant ATXN1 is expressed broadly throughout the brain, SCA1 is characterized by severe degeneration of cerebellar Purkinje cells (PCs). Despite major advances in dissecting the effects of mutant ATXN1 on Purkinje cells, much less is understood how cerebellar astrocytes and oligodendrocytes respond to and contribute to Purkinje cell dysfunction in SCA1. To address this question we performed cerebellar single nuclei RNA sequencing (snRNA seq) of early disease stage Pcp2-ATXN1[82Q] mice, a transgenic SCA1 mouse model expressing mutant ATXN1 only in Purkinje cells. We found no changes in cell numbers in the SCA1 cerebellum. We validated previously indicated pathway and gene expression changes in the Purkinje cells, and identified novel DEG and pathways in Purkinje cells, including Ralyl that may provide compensatory roles and maintain PC function. Importantly we identified profound non-cell autonomous and potentially neuroprotective gene expression and pathway alterations in Bergman glia, velate astrocytes and oligodendrocytes that may contribute to disease pathogenesis.

neuroscience↗

bioRxiv2021

Early stage of Spinocerebellar Ataxia Type 1 (SCA1) progression exhibits region- and cell-specific pathology and is partially ameliorated by Brain Derived Neurotrophic Factor (BDNF)

While astrocyte heterogeneity is an important feature of the healthy brain, less is understood about spatiotemporal heterogeneity of astrocytes in brain disease. Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease caused by a CAG repeat expansion mutation in the gene Ataxin1 (ATXN1). We characterized astrocytes across disease progression in the four clinically relevant brain regions, cerebellum, brainstem, hippocampus, and motor cortex of Atxn1154Q/2Q mice, a knock-in mouse model of SCA1. We found brain region specific changes in astrocyte density, GFAP expression and area, early in disease and prior to neuronal loss. Expression of astrocytic core homeostatic genes was also altered in a brain-region specific manner and correlated with neuronal activity indicating that astrocytes may compensate or exacerbate neuronal dysfunction in a brain region specific manner. Late in disease, expression of astrocytic homeostatic genes was reduced in all four brain regions indicating loss of astrocyte functions. We observed spatiotemporal changes in microglia with no obvious correlation with spatiotemporal astrocyte alterations indicating a complex orchestration of glial phenotypes in disease. These results support spatiotemporal diversity of glial phenotypes as an important feature of the brain disease that may contribute to SCA1 pathogenesis in a brain-region and disease stage-specific manner.

neuroscience↗

bioRxiv2020

Protein kinase CK2 alpha prime and alpha-synuclein constitute a key regulatory pathway in Huntington's disease

BackgroundHuntingtons Disease (HD) is a neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the HTT gene for which no therapies are available. This mutation causes HTT protein misfolding and aggregation, preferentially affecting medium spiny neurons (MSNs) of the basal ganglia. Transcriptional perturbations in synaptic genes and neuroinflammation are key processes that precede MSN dysfunction and motor symptom onset. Understanding the interplay between these processes is crucial to develop effective therapeutic strategies to treat HD. We investigated whether protein kinase CK2, a kinase upregulated in MSNs in HD and previously associated with Parkinsons disease (PD), participates in the regulation of neuroinflammation and synaptic function during HD progression. MethodsWe used the heterozygous knock-in zQ175 HD mouse model and compared that to zQ175 mice lacking one allele of CK2. We performed neuropathological analyses using immunohistochemistry, cytokine proteome profiling, RNA-seq analyses in the striatum, electrophysiological recordings, and behavioral analyses. We also used the murine immortalized striatal cell lines STHdhQ7 and STHdhQ111 and studied the expression of various synaptic genes dysregulated by CK2. ResultsWe showed that CK2 haploinsufficiency in zQ175 mice ameliorated neuroinflammation, HTT aggregation, transcriptional alterations, excitatory synaptic transmission, and motor coordination deficits. RNA-seq analyses also revealed a connection between -syn, a protein associated with PD, and the transcriptional perturbations mediated by CK2 in HD. We also found increased -syn serine 129 phosphorylation (pS129--syn), a post-translational modification linked to -synucleinopathy, in the nuclei of MSNs in zQ175 mice and in patients with HD. Levels of pS129--syn were ameliorated in zQ175 lacking one allele of CK2. ConclusionsOur data demonstrated that CK2 contributes to transcriptional dysregulation of synaptic genes and neuroinflammation in zQ175 mice and its depletion improved several HD-like phenotypes in this mouse model. These effects were related to increased phosphorylation of S129--syn in the striatum of HD mice, suggesting that CK2 contributes to worsening HD by mediating synucleinopathy. Our study highlights a possible convergent mechanism of neurodegeneration between HD and PD and suggests targeting CK2 as a potential therapeutic strategy to ameliorate synaptic dysfunction in HD as well as other neurodegenerative diseases.

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