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Cell Reports Dec 2023Cerebellar dysfunction has been linked to autism spectrum disorders (ASDs). Although cerebellar pathology has been observed in individuals with fragile X syndrome (FXS)...
Cerebellar dysfunction has been linked to autism spectrum disorders (ASDs). Although cerebellar pathology has been observed in individuals with fragile X syndrome (FXS) and in mouse models of the disorder, a cerebellar functional contribution to ASD-relevant behaviors in FXS has yet to be fully characterized. In this study, we demonstrate a critical cerebellar role for Fmr1 (fragile X messenger ribonucleoprotein 1) in ASD-relevant behaviors. First, we identify reduced social behaviors, sensory hypersensitivity, and cerebellar dysfunction, with loss of cerebellar Fmr1. We then demonstrate that cerebellar-specific expression of Fmr1 is sufficient to impact social, sensory, cerebellar dysfunction, and cerebro-cortical hyperexcitability phenotypes observed in global Fmr1 mutants. Moreover, we demonstrate that targeting the ASD-implicated cerebellar region Crus1 ameliorates behaviors in both cerebellar-specific and global Fmr1 mutants. Together, these results demonstrate a critical role for the cerebellar contribution to FXS-related behaviors, with implications for future therapeutic strategies.
Topics: Animals; Mice; Fragile X Syndrome; Autistic Disorder; Fragile X Mental Retardation Protein; Autism Spectrum Disorder; Disease Models, Animal; Cerebellar Diseases; Mice, Knockout
PubMed: 38048226
DOI: 10.1016/j.celrep.2023.113533 -
Nature Communications Feb 2024In the central nervous system, astrocytes enable appropriate synapse function through glutamate clearance from the synaptic cleft; however, it remains unclear how...
In the central nervous system, astrocytes enable appropriate synapse function through glutamate clearance from the synaptic cleft; however, it remains unclear how astrocytic glutamate transporters function at peri-synaptic contact. Here, we report that Down syndrome cell adhesion molecule (DSCAM) in Purkinje cells controls synapse formation and function in the developing cerebellum. Dscam-mutant mice show defects in CF synapse translocation as is observed in loss of function mutations in the astrocytic glutamate transporter GLAST expressed in Bergmann glia. These mice show impaired glutamate clearance and the delocalization of GLAST away from the cleft of parallel fibre (PF) synapse. GLAST complexes with the extracellular domain of DSCAM. Riluzole, as an activator of GLAST-mediated uptake, rescues the proximal impairment in CF synapse formation in Purkinje cell-selective Dscam-deficient mice. DSCAM is required for motor learning, but not gross motor coordination. In conclusion, the intercellular association of synaptic and astrocyte proteins is important for synapse formation and function in neural transmission.
Topics: Animals; Mice; Amino Acid Transport System X-AG; Cerebellum; Glutamic Acid; Neuroglia; Neurons; Purkinje Cells; Synapses
PubMed: 38302444
DOI: 10.1038/s41467-023-44579-z -
Cureus Aug 2023Lhermitte-Duclos disease (LDD), or dysplastic cerebellar gangliocytoma, is a rare benign tumor characterized by unilateral hemispheric cerebellar expansion. It is linked...
Lhermitte-Duclos disease (LDD), or dysplastic cerebellar gangliocytoma, is a rare benign tumor characterized by unilateral hemispheric cerebellar expansion. It is linked to mutations in the phosphatase and tensin homolog (PTEN) gene, which inhibit the phosphatidylinositol-3'-kinase pathway, leading to increased cell division and defective neuronal migration. This study aims to compare the clinical, radiological, histopathological, surgical resolution, and follow-up characteristics of reported cases of this rare condition. An in-depth search of LDD patients' clinical records at our institute between 2003 and 2023 was conducted, in addition to a systematic literature review on PubMed. Three patients with a diagnosis of LDD were found. Cerebellar abnormalities, varying headaches, and visual impairment were all present clinically. On T2 in the posterior fossa, all three MRI scans displayed the typical hyperintense parallel streak appearance. The histopathological report showed that large ganglion cells had replaced the granular layer, Purkinje cells had degenerated, the molecular layer had become hyper-myelinated, and synaptophysin and chromogranin were positive. Partial tumor resection and avoiding intracranial hypertension were the main goals of treatment. Genetic follow-up was conducted for all three patients. Neurosurgeons must be aware of LDD to provide close genetic monitoring despite the benign nature of the tumor because of its link to Cowden syndrome and elevated risk of cancer in other organs.
PubMed: 37779805
DOI: 10.7759/cureus.44326 -
IScience Feb 2024Fibroblast growth factor 9 (FGF9) is a member of the fibroblast growth factor family, which is widely expressed in the central nervous system (CNS). It has been reported...
Fibroblast growth factor 9 (FGF9) is a member of the fibroblast growth factor family, which is widely expressed in the central nervous system (CNS). It has been reported that deletion of FGF9 leads to defects in cerebellum development, including Purkinje cell defect. However, it is not clear how FGF9 regulating cerebellar development remains to be determined. Our results showed that in addition to disrupt Bergmann fiber scaffold formation and granule neuron migration, deletion of neuronal FGF9 led to ataxia defects. It affected development and function of Purkinje cells, and also changed the action potential threshold and excitation frequency. Mechanistically, depletion of FGF9 significantly changed neurotransmitter contents in Purkinje cells and led to preferential increase in inflammation, even downregulation in ERK signaling. Together, the data demonstrate that neuronal FGF9 is required for the development and function of Purkinje cells in the cerebellum. Insufficient FGF9 during cerebellum development will cause ataxia defects.
PubMed: 38352230
DOI: 10.1016/j.isci.2024.109039 -
Acta Neuropathologica Aug 2023Essential Tremor (ET) is a prevalent neurological disease characterized by an 8-10 Hz action tremor. Molecular mechanisms of ET remain poorly understood. Clinical data...
Essential Tremor (ET) is a prevalent neurological disease characterized by an 8-10 Hz action tremor. Molecular mechanisms of ET remain poorly understood. Clinical data suggest the importance of the cerebellum in disease pathophysiology, and pathological studies indicate Purkinje Cells (PCs) incur damage. Our recent cerebellar cortex and PC-specific transcriptome studies identified alterations in calcium (Ca) signaling pathways that included ryanodine receptor type 1 (RyR1) in ET. RyR1 is an intracellular Ca release channel located on the Endoplasmic Reticulum (ER), and in cerebellum is predominantly expressed in PCs. Under stress conditions, RyR1 undergoes several post-translational modifications (protein kinase A [PKA] phosphorylation, oxidation, nitrosylation), coupled with depletion of the channel-stabilizing binding partner calstabin1, which collectively characterize a "leaky channel" biochemical signature. In this study, we found markedly increased PKA phosphorylation at the RyR1-S2844 site, increased RyR1 oxidation and nitrosylation, and calstabin1 depletion from the RyR1 complex in postmortem ET cerebellum. Decreased calstabin1-RyR1-binding affinity correlated with loss of PCs and climbing fiber-PC synapses in ET. This 'leaky' RyR1 signature was not seen in control or Parkinson's disease cerebellum. Microsomes from postmortem cerebellum demonstrated excessive ER Ca leak in ET vs. controls, attenuated by channel stabilization. We further studied the role of RyR1 in tremor using a mouse model harboring a RyR1 point mutation that mimics constitutive site-specific PKA phosphorylation (RyR1-S2844D). RyR1-S2844D homozygous mice develop a 10 Hz action tremor and robust abnormal oscillatory activity in cerebellar physiological recordings. Intra-cerebellar microinfusion of RyR1 agonist or antagonist, respectively, increased or decreased tremor amplitude in RyR1-S2844D mice, supporting a direct role of cerebellar RyR1 leakiness for tremor generation. Treating RyR1-S2844D mice with a novel RyR1 channel-stabilizing compound, Rycal, effectively dampened cerebellar oscillatory activity, suppressed tremor, and normalized cerebellar RyR1-calstabin1 binding. These data collectively support that stress-associated ER Ca leak via RyR1 may contribute to tremor pathophysiology.
Topics: Humans; Ryanodine Receptor Calcium Release Channel; Calcium; Tremor; Cerebellum; Endoplasmic Reticulum; Muscle, Skeletal
PubMed: 37335342
DOI: 10.1007/s00401-023-02602-z -
Theranostics 2024The neurobiological basis of gaining consciousness from unconscious state induced by anesthetics remains unknown. This study was designed to investigate the involvement...
The neurobiological basis of gaining consciousness from unconscious state induced by anesthetics remains unknown. This study was designed to investigate the involvement of the cerebello-thalamus-motor cortical loop mediating consciousness transitions from the loss of consciousness (LOC) induced by an inhalational anesthetic sevoflurane in mice. The neural tracing and fMRI together with optochemogenetic manipulation were used to investigate the potential link among cerebello-thalamus-motor cortical brain regions. The fiber photometry of calcium and neurotransmitters, including glutamate (Glu), γ-aminobutyric acid (GABA) and norepinephrine (NE), were monitored from the motor cortex (M1) and the 5 lobule of the cerebellar vermis (5Cb) during unconsciousness induced by sevoflurane and gaining consciousness after sevoflurane exposure. Cerebellar Purkinje cells were optogenetically manipulated to investigate their influence on consciousness transitions during and after sevoflurane exposure. Activation of 5Cb Purkinje cells increased the Ca flux in the M1 CaMKIIα neurons, but this increment was significantly reduced by inactivation of posterior and parafascicular thalamic nucleus The 5Cb and M1 exhibited concerted calcium flux, and glutamate and GABA release during transitions from wakefulness, loss of consciousness, burst suppression to conscious recovery. Ca flux and Glu release in the M1, but not in the 5Cb, showed a strong synchronization with the EEG burst suppression, particularly, in the gamma-band range. In contrast, the Glu, GABA and NE release and Ca oscillations were coherent with the EEG gamma band activity only in the 5Cb during the pre-recovery of consciousness period. The optogenetic activation of Purkinje cells during burst suppression significantly facilitated emergence from anesthesia while the optogenetic inhibition prolonged the time to gaining consciousness. Our data indicate that cerebellar neuronal communication integrated with motor cortex through thalamus promotes consciousness recovery from anesthesia which may likely serve as arousal regulation.
Topics: Mice; Animals; Consciousness; Sevoflurane; Purkinje Cells; Calcium; Motor Cortex; Unconsciousness; Neurons; Anesthesia; Glutamates; gamma-Aminobutyric Acid
PubMed: 38169536
DOI: 10.7150/thno.89592 -
Brain Communications 2023Disease mechanisms underlying neurological and neuropsychiatric symptoms after coronavirus disease 2019 (COVID-19), termed neuro-COVID, are poorly understood....
Disease mechanisms underlying neurological and neuropsychiatric symptoms after coronavirus disease 2019 (COVID-19), termed neuro-COVID, are poorly understood. Investigations of the cerebrospinal fluid (CSF) for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA and antibodies, as well as autoantibodies against neuronal surface antigens, could improve our understanding in that regard. We prospectively collected CSF and blood from patients investigated by lumbar puncture for neurological or neuropsychiatric symptoms during or after COVID-19. Primary outcomes were the presence of (i) SARS-CoV-2 RNA in CSF via polymerase chain reaction (PCR), (ii) SARS-CoV-2 immunoglobulin G (IgG) anti-S receptor-binding-domain antibodies via the Euroimmun and Wantai assays and (iii) IgG autoantibodies against neuronal surface antigens using commercial cell- and tissue-based assays (Euroimmun). Secondary outcomes were (i) routine CSF investigations and (ii) correlation between SARS-CoV-2 antibody levels in CSF with serum levels, blood-brain barrier permeability and peripheral inflammation. We obtained CSF from 38 COVID-19 patients (mean age 56.5 ± 19.2 years, 53% women) who developed neurological and neuropsychiatric symptoms. CSF pleocytosis (>5 cells) was observed in 9/38 patients (23.7%), elevated CSF protein (>0.50 g/L) in 13/38 (34.2%) and elevated CSF/serum albumin ratio in 12/35 (34.3%). PCR for SARS-CoV-2 RNA in CSF was negative in all. SARS-CoV-2 CSF antibodies were detected in 15/34 (44.1%; Euroimmun assay) and 7/31 (22.6%; Wantai assay) individuals, but there were no signs of intrathecal SARS-CoV-2 IgG production. SARS-CoV-2 CSF antibodies were positively correlated with serum levels ( = 0.93, < 0.001), blood-brain barrier permeability ( = 0.47, = 0.006), peripheral inflammation ( = 0.51, = 0.002) and admission to the intensive care unit [odds ratio (OR) 17.65; 95% confidence interval (CI) 1.18-264.96; = 0.04; = 15]. Cell-based assays detected weakly positive NMDAR, LGI1 and CASPR2 antibodies in serum of 4/34 (11.8%) patients but not in CSF. The tissue-based assay showed anti-neuronal fluorescence in CSF from one individual, staining for Purkinje cells. In summary, whereas we did not detect active SARS-CoV-2 infection in the CSF, SARS-CoV-2 antibodies were prevalent. The absence of intrathecal antibody production points towards blood-brain barrier impairment as the origin of CSF SARS-CoV-2 antibodies. In contrast, CSF autoantibodies against neuronal surface antigens were rare. There was no evidence for a clinical correlate of these antibodies. We conclude that, rather than specific autoimmune neuronal injury, non-specific effects of critical illness including an impaired blood-brain barrier are more likely to contribute to neuro-COVID.
PubMed: 37908236
DOI: 10.1093/braincomms/fcad274 -
BioRxiv : the Preprint Server For... Sep 2023Brain computations are dictated by the unique morphology and connectivity of neuronal subtypes, features established by closely timed developmental events. MicroRNAs...
UNLABELLED
Brain computations are dictated by the unique morphology and connectivity of neuronal subtypes, features established by closely timed developmental events. MicroRNAs (miRNAs) are critical for brain development, but current technologies lack the spatiotemporal resolution to determine how miRNAs instruct the steps leading to subtype identity. Here, we developed new tools to tackle this major gap. Fast and reversible miRNA loss-of-function revealed that miRNAs are necessary for cerebellar Purkinje cell (PC) differentiation, which previously appeared miRNA-independent, and resolved distinct miRNA critical windows in PC dendritogenesis and climbing fiber synaptogenesis, key determinants of PC identity. To identify underlying mechanisms, we generated a mouse model, which enables precise mapping of miRNAs and their targets in rare cell types. With PC-specific maps, we found that the PC-enriched miR-206 drives exuberant dendritogenesis and modulates synaptogenesis. Our results showcase vastly improved approaches for dissecting miRNA function and reveal that many critical miRNA mechanisms remain largely unexplored.
HIGHLIGHTS
Fast miRNA loss-of-function with T6B impairs postnatal Purkinje cell developmentReversible T6B reveals critical miRNA windows for dendritogenesis and synaptogenesisConditional Spy3-Ago2 mouse line enables miRNA-target network mapping in rare cellsPurkinje cell-enriched miR-206 regulates its unique dendritic and synaptic morphology.
PubMed: 37808721
DOI: 10.1101/2023.09.28.560023 -
Molecular Psychiatry Sep 2023Although circadian and sleep disorders are frequently associated with autism spectrum disorders (ASD), it remains elusive whether clock gene disruption can lead to...
Although circadian and sleep disorders are frequently associated with autism spectrum disorders (ASD), it remains elusive whether clock gene disruption can lead to autistic-like phenotypes in animals. The essential clock gene Bmal1 has been associated with human sociability and its missense mutations are identified in ASD. Here we report that global Bmal1 deletion led to significant social impairments, excessive stereotyped and repetitive behaviors, as well as motor learning disabilities in mice, all of which resemble core behavioral deficits in ASD. Furthermore, aberrant cell density and immature morphology of dendritic spines were identified in the cerebellar Purkinje cells (PCs) of Bmal1 knockout (KO) mice. Electrophysiological recordings uncovered enhanced excitatory and inhibitory synaptic transmission and reduced firing rates in the PCs of Bmal1 KO mice. Differential expression of ASD- and ataxia-associated genes (Ntng2, Mfrp, Nr4a2, Thbs1, Atxn1, and Atxn3) and dysregulated pathways of translational control, including hyperactivated mammalian target of rapamycin complex 1 (mTORC1) signaling, were identified in the cerebellum of Bmal1 KO mice. Interestingly, the antidiabetic drug metformin reversed mTORC1 hyperactivation and alleviated major behavioral and PC deficits in Bmal1 KO mice. Importantly, conditional Bmal1 deletion only in cerebellar PCs was sufficient to recapitulate autistic-like behavioral and cellular changes akin to those identified in Bmal1 KO mice. Together, these results unveil a previously unidentified role for Bmal1 disruption in cerebellar dysfunction and autistic-like behaviors. Our findings provide experimental evidence supporting a putative role for dysregulation of circadian clock gene expression in the pathogenesis of ASD.
Topics: Animals; Mice; Mice, Inbred C57BL; Mice, Knockout; ARNTL Transcription Factors; Social Interaction; Humans; Stereotyped Behavior; Learning; Cerebellum; Purkinje Cells; Electrophysiology; Autism Spectrum Disorder; Protein Biosynthesis; Metformin; Mechanistic Target of Rapamycin Complex 1
PubMed: 35301425
DOI: 10.1038/s41380-022-01499-6 -
Communications Biology Jan 2024Purkinje cells in the cerebellum are among the largest neurons in the brain and have been extensively investigated in rodents. However, their morphological and...
Purkinje cells in the cerebellum are among the largest neurons in the brain and have been extensively investigated in rodents. However, their morphological and physiological properties remain poorly understood in humans. In this study, we utilized high-resolution morphological reconstructions and unique electrophysiological recordings of human Purkinje cells ex vivo to generate computational models and estimate computational capacity. An inter-species comparison showed that human Purkinje cell had similar fractal structures but were larger than those of mouse Purkinje cells. Consequently, given a similar spine density (2/μm), human Purkinje cell hosted approximately 7.5 times more dendritic spines than those of mice. Moreover, human Purkinje cells had a higher dendritic complexity than mouse Purkinje cells and usually emitted 2-3 main dendritic trunks instead of one. Intrinsic electro-responsiveness was similar between the two species, but model simulations revealed that the dendrites could process ~6.5 times (n = 51 vs. n = 8) more input patterns in human Purkinje cells than in mouse Purkinje cells. Thus, while human Purkinje cells maintained spike discharge properties similar to those of rodents during evolution, they developed more complex dendrites, enhancing computational capacity.
Topics: Animals; Mice; Humans; Purkinje Cells; Cerebellum; Neurons; Dendrites
PubMed: 38168772
DOI: 10.1038/s42003-023-05689-y