RNA Foci in Two bi-Allelic RFC1 Expansion Carriers.

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a late-onset, autosomal recessive neurodegenerative disorder caused by biallelic AAGGG/ACAGG repeat expansion (AAGGG-exp/ACAGG-exp) in RFC1. The recent identification of patients with CANVAS exhibiting compound heterozygosity for AAGGG-exp and truncating variants supports the loss-of-function of RFC1 in CANVAS patients. We investigated the pathological changes in 2 autopsied patients with CANVAS harboring biallelic ACAGG-exp and AAGGG-exp. RNA fluorescence in situ hybridization of the 2 patients revealed CCTGT- and CCCTT-containing RNA foci, respectively, in neuronal nuclei of tissues with neuronal loss. Our findings suggest that RNA toxicity may be involved in the pathogenesis of CANVAS. ANN NEUROL 2024;95:607-613.

Lateral olfactory tract usher substance (LOTUS), an endogenous Nogo receptor antagonist, ameliorates disease progression in amyotrophic lateral sclerosis model mice.

Nogo-Nogo receptor 1 (NgR1) signaling is significantly implicated in neurodegeneration in amyotrophic lateral sclerosis (ALS). We previously showed that lateral olfactory tract usher substance (LOTUS) is an endogenous antagonist of NgR1 that prevents all myelin-associated inhibitors (MAIs), including Nogo, from binding to NgR1. Here we investigated the role of LOTUS in ALS pathogenesis by analyzing G93A-mutated human superoxide dismutase 1 (SOD1) transgenic (Tg) mice, as an ALS model, as well as newly generated LOTUS-overexpressing SOD1 Tg mice. We examined expression profiles of LOTUS and MAIs and compared motor functions and survival periods in these mice. We also investigated motor neuron survival, glial proliferation in the lumbar spinal cord, and neuromuscular junction (NMJ) morphology. We analyzed downstream molecules of NgR1 signaling such as ROCK2, LIMK1, cofilin, and ataxin-2, and also neurotrophins. In addition, we investigated LOTUS protein levels in the ventral horn of ALS patients. We found significantly decreased LOTUS expression in both SOD1 Tg mice and ALS patients. LOTUS overexpression in SOD1 Tg mice increased lifespan and improved motor function, in association with prevention of motor neuron loss, reduced gliosis, increased NMJ innervation, maintenance of cofilin phosphorylation dynamics, decreased levels of ataxin-2, and increased levels of brain-derived neurotrophic factor (BDNF). Reduced LOTUS expression may enhance neurodegeneration in SOD1 Tg mice and ALS patients by activating NgR1 signaling, and in this study LOTUS overexpression significantly ameliorated ALS pathogenesis. LOTUS might serve as a promising therapeutic target for ALS.

Phosphorylated CRMP1, axon guidance protein, is a component of spheroids and is involved in axonal pathology in amyotrophic lateral sclerosis.

In amyotrophic lateral sclerosis (ALS), neurodegeneration is characterized by distal axonopathy that begins at the distal axons, including the neuromuscular junctions, and progresses proximally in a "dying back" manner prior to the degeneration of cell bodies. However, the molecular mechanism for distal axonopathy in ALS has not been fully addressed. Semaphorin 3A (Sema3A), a repulsive axon guidance molecule that phosphorylates collapsin response mediator proteins (CRMPs), is known to be highly expressed in Schwann cells near distal axons in a mouse model of ALS. To clarify the involvement of Sema3A-CRMP signaling in the axonal pathogenesis of ALS, we investigated the expression of phosphorylated CRMP1 (pCRMP1) in the spinal cords of 35 patients with sporadic ALS and seven disease controls. In ALS patients, we found that pCRMP1 accumulated in the proximal axons and co-localized with phosphorylated neurofilaments (pNFs), which are a major protein constituent of spheroids. Interestingly, the pCRMP1:pNF ratio of the fluorescence signal in spheroid immunostaining was inversely correlated with disease duration in 18 evaluable ALS patients, indicating that the accumulation of pCRMP1 may precede that of pNFs in spheroids or promote ALS progression. In addition, overexpression of a phospho-mimicking CRMP1 mutant inhibited axonal outgrowth in Neuro2A cells. Taken together, these results indicate that pCRMP1 may be involved in the pathogenesis of axonopathy in ALS, leading to spheroid formation through the proximal progression of axonopathy.

Anti-inflammatory effects of siponimod on astrocytes.

Siponimod, which is approved to treat active secondary progressive multiple sclerosis, acts as a functional antagonist of sphingosine-1-phosphate (S1P) receptor 1 (S1P1) and an agonist of S1P5. S1P1 antagonization, which inhibits lymphocyte egress from lymphoid tissues and subsequent infiltration into the central nervous system (CNS), is considered the main therapeutic mechanism of siponimod. In addition, siponimod's direct effects on CNS glial cells are another potential neuroprotective mechanism because siponimod can penetrate the blood-brain barrier and CNS glial cells express S1P receptors. However, it remains uncertain whether siponimod directly affects CNS glial cells. In this study, we investigated siponimod's effects on astrocytes using mouse primary cultures. Siponimod suppressed nuclear factor kappa B activation and pro-inflammatory cytokine production. Using antagonists for S1P1 and S1P5, we found that siponimod partially exerts its anti-inflammatory effects via S1P1, but not via S1P5. Moreover, siponimod also inhibited histone deacetylase, suggesting that siponimod exerts broad anti-inflammatory effects via S1P1 antagonization and histone deacetylase inhibition. Siponimod might suppress disease progression in multiple sclerosis in part via direct inhibition of astroglial CNS neuroinflammation.

Ocular flutter as the presenting manifestation of autoimmune glial fibrillary acidic protein astrocytopathy.

A 39-year-old man exhibited ocular flutter and cerebellar ataxia following a subacute disturbance of consciousness and partial seizure. He was diagnosed with autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy by tissue- and cell-based antibody assays. Brain single-photon emission computed tomography detected a significant increase in blood flow in the fastigial nucleus, a critical region for eye saccade control. Immunotherapies diminished the ocular flutter and reduced hyperperfusion in the fastigial nucleus. This case suggests that autoimmune GFAP astrocytopathy can cause ocular flutter and provides strong imaging evidence supporting the hypothesis that ocular flutter is caused by hyperactivity or disinhibition of the fastigial nucleus.

Inhibition of Crmp1 Phosphorylation at Ser522 Ameliorates Motor Function and Neuronal Pathology in Amyotrophic Lateral Sclerosis Model Mice.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive and fatal neurodegenerative disorder that affects upper and lower motor neurons; however, its pathomechanism has not been fully elucidated. Using a comprehensive phosphoproteomic approach, we have identified elevated phosphorylation of Collapsin response mediator protein 1 (Crmp1) at serine 522 in the lumbar spinal cord of ALS model mice overexpressing a human superoxide dismutase mutant (SOD1G93A). We investigated the effects of Crmp1 phosphorylation and depletion in SOD1G93A mice using Crmp1S522A (Ser522→Ala) knock-in (Crmp1ki/ki ) mice in which the S522 phosphorylation site was abolished and Crmp1 knock-out (Crmp1-/-) mice, respectively. Crmp1ki/ki /SOD1G93A mice showed longer latency to fall in a rotarod test while Crmp1-/-/SOD1G93A mice showed shorter latency compared with SOD1G93A mice. Survival was prolonged in Crmp1ki/ki /SOD1G93A mice but not in Crmp1-/-/SOD1G93A mice. In agreement with these phenotypic findings, residual motor neurons and innervated neuromuscular junctions (NMJs) were comparatively well-preserved in Crmp1ki/ki /SOD1G93A mice without affecting microglial and astroglial pathology. Pathway analysis of proteome alterations showed that the sirtuin signaling pathway had opposite effects in Crmp1ki/ki /SOD1G93A and Crmp1-/-/SOD1G93A mice. Our study indicates that modifying CRMP1 phosphorylation is a potential therapeutic strategy for ALS.

Sensory Ataxic Guillain-Barré Syndrome with Dysgeusia after mRNA COVID-19 Vaccination.

Guillain-Barré syndrome (GBS) has occasionally occurred in people who have received coronavirus disease 2019 (COVID-19) vaccines. Dysgeusia is rare symptom of GBS. We herein report a rare case of sensory ataxic GBS with dysgeusia just after the second dose of the Pfizer-BioNTech COVID-19 vaccine. Although autoantibodies against glycolipids were not detected, immunotherapy with intravenous immunoglobulin and methylprednisolone pulse therapy effectively ameliorated the symptoms. Our report suggests that the COVID-19 vaccine may induce various clinical subtypes of GBS, including a rare variant with sensory ataxia and dysgeusia.

SGTA associates with intracellular aggregates in neurodegenerative diseases.

Intracellular aggregates are a common pathological hallmark of neurodegenerative diseases such as polyglutamine (polyQ) diseases, amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and multiple system atrophy (MSA). Aggregates are mainly formed by aberrant disease-specific proteins and are accompanied by accumulation of other aggregate-interacting proteins. Although aggregate-interacting proteins have been considered to modulate the formation of aggregates and to be involved in molecular mechanisms of disease progression, the components of aggregate-interacting proteins remain unknown. In this study, we showed that small glutamine-rich tetratricopeptide repeat-containing protein alfa (SGTA) is an aggregate-interacting protein in neurodegenerative diseases. Immunohistochemistry showed that SGTA interacted with intracellular aggregates in Huntington disease (HD) cell models and neurons of HD model mice. We also revealed that SGTA colocalized with intracellular aggregates in postmortem brains of patients with polyQ diseases including spinocerebellar ataxia (SCA)1, SCA2, SCA3, and dentatorubral-pallidoluysian atrophy. In addition, SGTA colocalized with glial cytoplasmic inclusions in the brains of MSA patients, whereas no accumulation of SGTA was observed in neurons of PD and ALS patients. In vitro study showed that SGTA bound to polyQ aggregates through its C-terminal domain and SGTA overexpression reduced intracellular aggregates. These results suggest that SGTA may play a role in the formation of aggregates and may act as potential modifier of molecular pathological mechanisms of polyQ diseases and MSA.

[A case of subacute hypertrophic pachymeningitis caused by Pseudomonas aeruginosa infection presenting with subdural hygroma].

A 78-year-old woman with bilateral fungal sinusitis, which resulted in right orbital apex syndrome, underwent endoscopic sinus surgery and optic nerve decompression. Two months after the operation, she complained of anxiety and insomnia. Head CT showed subdural hematoma-like effusion and burr hole drainage was conducted. The collected fluid was not hematoma, but bloody, xanthochromic effusion with no pathogenic bacteria. Ten days later, she underwent drainage and dural biopsy after craniotomy because of relapse of subdural hygroma and progression of hypertrophic pachymeningitis associated with aggravation of psychiatric symptoms. A sample of the dura mater showed dense fibrosis with thickening, and Pseudomonas aeruginosa (P. aeruginosa) was detected by culture. Although otitis or sinusitis secondary to P. aeruginosa infection has been reported as a leading cause of infectious pachymeningitis, psychiatric symptoms alone and concomitant refractory subdural hygroma are atypical and unreported manifestations. In patients with pachymeningitis and a history of transnasal endoscopic surgery, P. aeruginosa infection should be considered, irrespective of an atypical clinical course and negative blood or fluid culture. Additionally, dural biopsy might help in detection of pathogenic bacteria.

CCR2 is localized in microglia and neurons, as well as infiltrating monocytes, in the lumbar spinal cord of ALS mice.

It remains controversial whether circulating monocytes expressing CCR2 infiltrate the central nervous system (CNS) and contribute to pathogenicity of amyotrophic lateral sclerosis (ALS). A previous report used conventional immunohistochemistry to show that CCR2 is exclusively expressed by astrocytes, but not infiltrating monocytes/microglia or neurons, in the spinal cords of ALS model mice. In this study, we assessed the cellular distribution of CCR2 in the CNS of ALS mice using CCR2-reporter mice (Ccr2rfp/+-Cx3cr1gfp/+-SOD1G93A Tg mice), a more sophisticated method for directly detecting the distribution of CCR2 protein. We found that infiltration of CCR2+ monocytes in the lumbar spinal cord increased over the course of disease progression. Moreover, from the middle stage of disease, CCR2 was partially distributed in microglia and neurons, but not astrocytes, in striking contrast to the previous findings. These novel observations suggested that CCR2+ monocyte infiltration leads to CNS environmental deterioration due to toxic conversion of microglia and neurons, creating a vicious cycle of neuroinflammation and leading to acceleration of ALS pathology. Our findings also show that this reporter mouse is a useful and powerful tool for obtaining new insights into the pathomechanisms of ALS.

Long-read sequencing identifies the pathogenic nucleotide repeat expansion in RFC1 in a Japanese case of CANVAS.

Recently, a recessively inherited intronic repeat expansion in replication factor C1 (RFC1) was identified in cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS). Here, we describe a Japanese case of genetically confirmed CANVAS with autonomic failure and auditory hallucination. The case showed impaired uptake of iodine-123-metaiodobenzylguanidine and 123I-ioflupane in the cardiac sympathetic nerve and dopaminergic neurons, respectively, by single-photon emission computed tomography. Long-read sequencing identified biallelic pathogenic (AAGGG)n nucleotide repeat expansion in RFC1 and heterozygous benign (TAAAA)n and (TAGAA)n expansions in brain expressed, associated with NEDD4 (BEAN1). Enrichment of the repeat regions in RFC1 and BEAN1 using a Cas9-mediated system clearly distinguished between pathogenic and benign repeat expansions. The haplotype around RFC1 indicated that the (AAGGG)n expansion in our case was on the same ancestral allele as that of European cases. Thus, long-read sequencing facilitates precise genetic diagnosis of diseases with complex repeat structures and various expansions.

Ataxic phenotype with altered CaV3.1 channel property in a mouse model for spinocerebellar ataxia 42.

Spinocerebellar ataxia 42 (SCA42) is a neurodegenerative disorder recently shown to be caused by c.5144G > A (p.Arg1715His) mutation in CACNA1G, which encodes the T-type voltage-gated calcium channel CaV3.1. Here, we describe a large Japanese family with SCA42. Postmortem pathological examination revealed severe cerebellar degeneration with prominent Purkinje cell loss without ubiquitin accumulation in an SCA42 patient. To determine whether this mutation causes ataxic symptoms and neurodegeneration, we generated knock-in mice harboring c.5168G > A (p.Arg1723His) mutation in Cacna1g, corresponding to the mutation identified in the SCA42 family. Both heterozygous and homozygous mutants developed an ataxic phenotype from the age of 11-20 weeks and showed Purkinje cell loss at 50 weeks old. Degenerative change of Purkinje cells and atrophic thinning of the molecular layer were conspicuous in homozygous knock-in mice. Electrophysiological analysis of Purkinje cells using acute cerebellar slices from young mice showed that the point mutation altered the voltage dependence of CaV3.1 channel activation and reduced the rebound action potentials after hyperpolarization, although it did not significantly affect the basic properties of synaptic transmission onto Purkinje cells. Finally, we revealed that the resonance of membrane potential of neurons in the inferior olivary nucleus was decreased in knock-in mice, which indicates that p.Arg1723His CaV3.1 mutation affects climbing fiber signaling to Purkinje cells. Altogether, our study shows not only that a point mutation in CACNA1G causes an ataxic phenotype and Purkinje cell degeneration in a mouse model, but also that the electrophysiological abnormalities at an early stage of SCA42 precede Purkinje cell loss.

Cerebellar ataxia-dominant phenotype in patients with ERCC4 mutations.

Autosomal recessive cerebellar ataxias (ARCAs) are clinically and genetically heterogeneous neurological disorders. Through whole-exome sequencing of Japanese ARCA patients, we identified three index patients from unrelated families who had biallelic mutations in ERCC4. ERCC4 mutations have been known to cause xeroderma pigmentosum complementation group F (XP-F), Cockayne syndrome, and Fanconi anemia phenotypes. All of the patients described here showed very slowly progressive cerebellar ataxia and cognitive decline with choreiform involuntary movement, with young adolescent or midlife onset. Brain MRI demonstrated atrophy that included the cerebellum and brainstem. Of note, cutaneous symptoms were very mild: there was normal to very mild pigmentation of exposed skin areas and/or an equivocal history of pathological sunburn. However, an unscheduled DNA synthesis assay of fibroblasts from the patient revealed impairment of nucleotide excision repair. A similar phenotype was very recently recognized through genetic analysis of Caucasian cerebellar ataxia patients. Our results confirm that biallelic ERCC4 mutations cause a cerebellar ataxia-dominant phenotype with mild cutaneous symptoms, possibly accounting for a high proportion of the genetic causes of ARCA in Japan, where XP-F is prevalent.

Matrin 3 Is a Component of Neuronal Cytoplasmic Inclusions of Motor Neurons in Sporadic Amyotrophic Lateral Sclerosis.

Mutations in the MATR3 gene have been identified as a cause of familial amyotrophic lateral sclerosis, but involvement of the matrin 3 (MATR3) protein in sporadic amyotrophic lateral sclerosis (SALS) pathology has not been fully assessed. We immunohistochemically analyzed MATR3 pathology in the spinal cords of SALS and control autopsy specimens. MATR3 immunostaining of the motor neuron nuclei revealed two distinct patterns: mild and strong staining. There were no differences in the ratio of mild versus strong nuclear staining between the SALS and control cases. MATR3-containing neuronal cytoplasmic inclusions (NCIs) were observed in 60% of SALS cases. Most motor neurons with MATR3-positive NCIs exhibited a mild nuclear staining pattern. Although 16.8% of NCIs positive for transactivating response region DNA-binding protein 43 (TDP-43) were estimated as double-labeled by MATR3, no MATR3-positive or TDP-43-negative NCIs were observed. Although a previous study found that MATR3-positive NCIs are present only in cases with C9orf72 hexanucleotide repeat expansion, ubiquitin-positive granular NCIs were not observed in the cerebellum, which have been reported as specific to C9orf72-related ALS. Six ALS cases were confirmed to be negative for the GGGGCC hexanucleotide. Our results reveal that MATR3 is a component of TDP-43-positive NCIs in motor neurons, even in SALS, and indicate the broader involvement of MATR3 in ALS pathology and the heterogeneity of TDP-43-positive NCIs.

A Japanese case of cerebellar ataxia, spastic paraparesis and deep sensory impairment associated with a novel homozygous TTC19 mutation.

Mitochondrial complex III (CIII) deficiency comprises a group of complex and heterogeneous genetic disorders. TTC19 mutations constitute a rare cause of CIII deficiency and are associated with neurological disorders in childhood and adulthood. Herein, we describe a 27-year-old Japanese man with cerebellar ataxia, spastic paraparesis, loss of deep sensation, mild frontal lobe dysfunction and transient psychiatric symptoms. Brain magnetic resonance imaging showed cerebellar atrophy and bilateral high-intensity signals in the inferior olives and regions adjacent to periaqueductal gray matter, on T2-weighted images. On whole-exome sequencing, we detected a novel homozygous frameshift mutation c.157_158dup [p.Pro54Alafs*48] in TTC19. Mitochondrial enzyme assays confirmed mild impairment of CIII enzymatic activity in lymphoblasts, which was consistent with TTC19-related CIII deficiency. His symptoms and radiological findings demonstrated an early stage or mild form of this disease, and further clarify the characteristics of patients with rare TTC19 mutations.

Guided supramolecular polymerization of oligo(p-phenylenevinylene) functionalized bismelamines.

Bismelamines end-functionalized with oligo(p-phenylenevinylene) self-aggregate in nonpolar solvent to form short nanorods by helical π-π stacking. This inherent self-aggregation can be guided to a supramolecular polymerization pathway by complexing with a cyanurate, leading to gel-forming elongated nanotapes lacking the helical sense of the π-conjugated moieties.

Rational design of nanofibers and nanorings through complementary hydrogen-bonding interactions of functional pi systems.

A simple protocol to create nanofibers and -rings through a rational self-assembly approach is described. Whereas the melamine-oligo(p-phenylenevinylene) conjugate 1a self-aggregates to form ill-defined nanostructures, conjugate 1b, which possesses an amide group as an additional interactive site, self-aggregates to form 1D nanofibers that induce gelation of the solvent. AFM and XRD studies have shown that dimerization through the melamine-melamine hydrogen-bonding interaction occurs only for 1b. Upon complexation with 1/3 equivalents of cyanuric acid (CA), conjugate 1a provides well-defined, ring-shaped nanostructures at micromolar concentrations, which open to form fibrous assemblies at submillimolar concentrations and organogels in the millimolar concentration range. Apparently, the enhanced aggregation ability of 1a by CA is a consequence of columnar organization of the resulting discotic complex 1a(3).CA. In contrast, coaggregation of 1b with CA does not provide well-defined nanostructures, probably due to the interference of complementary hydrogen-bonding interactions by the amide group.

Two-dimensional organization of mono- and bisurea supramolecular polymers studied by scanning tunneling microscopy.

Scanning tunneling microscopy (STM) of mono- and bisurea-functionalized oligo(p-phenylenevinylene)s at solid/liquid interface visualized two-dimensionally-ordered double columnar structures of pi-conjugated segments scaffolded by one-dimensional supramolecular polymerization of urea hydrogen-bonding units. In contrast to a persistent alignment of the bisurea compound supported by twofold intermolecular urea-urea hydrogen-bonding, the building blocks in the monourea double columns shows dynamic fluctuation and defects because of their rotational motion around urea-urea hydrogen-bonding axis and/or adsorption-desorption of the individual molecules from the surface. Self-assembled structures of mono- and bisurea compounds at solid/liquid interface revealed by STM can be related to their gelation abilities in organic solvents.

Reversible transformation between rings and coils in a dynamic hydrogen-bonded self-assembly.

Several proteins, such as tobacco mosaic virus coat protein and the beta protein of the bacteriophage lambda, are known to exhibit unique dynamic self-organization processes involving ring-shaped and extended helical nanostructures triggered by chemical stimuli. However, transformation of rings into coils as observed in biological assemblies has never been realized with synthetic molecular building blocks. Oligo(p-phenylenevinylene) functionalized on one end with barbituric acid and on the other end with aliphatic tails self-organizes in aliphatic solvents to form nanorings through hydrogen-bonding and pi-stacking interactions. Upon an increase in concentration, the nanorings transform into rodlike nanostructures, which are considered to be formed through helically coiled objects consisting of quasi-one-dimensional fibers.

Cyanurate-guided self-assembly of a melamine-capped oligo(p-phenylenevinylene).

An oligo(p-phenylenevinylene) capped on one end by a monotopic DAD-type triple hydrogen-bonding module shows distinct optical properties as well as self-organization behavior upon complexation with cyanurates with different numbers of ADA-type triple hydrogen-bonding sites.