Protective roles of carbonic anhydrase 8 in Machado–Joseph Disease

Machado–Joseph disease (MJD)/Spinocerebellar ataxia type 3 (SCA3) is an inherited neurodegenerative disease that can lead to a regression of motor coordination and muscle control in the extremities. It is known that expansion of CAG repeats encodes abnormally long polyQ in mutant ataxin-3, the disease protein. It is also noted that mutant ataxin-3 interacts with 1,4,5-trisphosphate receptor type 1 (IP3R1) and induces abnormal Ca²⁺ release. Previously, we have shown a significant increase in the expression of carbonic anhydrase VIII (CA8) in SK-N-SH-MJD78 cells, which are human neuroblastoma cells overexpressing mutant ataxin-3 with 78 glutamine repeats. In the current study, we showed the presence of significantly increased CA8 expression in MJD mouse cerebellum in either early or late disease stage, with a gradual decrease in CA8 expression as the MJD mice naturally aged. By immunofluorescence and immunoprecipitation analysis, we also found that CA8 co-localized and interacted with mutant ataxin-3 in SK-N-SH-MJD78 cells harboring overexpressed CA8 (SK-MJD78-CA8). In addition, we found that SK-MJD78-CA8 cells, as well as cerebellar granule neurons (CGNs) of MJD transgenic (Tg) mouse with overexpressed CA8, were more resistant to reactive oxygen species (ROS) stress than the control cells. Importantly, overexpression of CA8 in SK-MJD78-CA8 cells and in MJD CGNs rescued abnormal Ca²⁺ release and caused an increase in cell survival. In summary, we demonstrate the protective function of CA8 in MJD disease models and speculate that the declining expression of CA8 following an initial increased expression may be related to the late onset phenomenon of MJD.     

Cutaneous Sympathetic Dysfunction in Patients with Machado–Joseph Disease

Although the clinical symptoms of Machado–Joseph disease (MJD) vary widely, those involving the autonomic nervous system, such as cutaneous sympathetic dysfunction, have rarely been investigated. In addition, there are no reports on cutaneous vasomotor function in patients with MJD. To determine the effects of MJD on cutaneous sympathetic function, we evaluated cutaneous vasomotor and sudomotor responses in the palms of 15 patients (mean age, 49?±?15 years; seven men and eight women) who were genetically diagnosed with MJD as well as in the palms of 15 age-matched, healthy controls (mean age, 48?±?16 years; nine men and six women). Sweat response was absent in 10 (67 %) patients with MJD, and the mean amplitude of sweat response was significantly lower (p?<?0.0001) in patients with MJD than in healthy controls following mental stress (mental arithmetic) and physiological stimuli. Although vasoconstrictive response was absent in three patients with MJD (20 %), there were no significant differences in the mean amplitude of vasoconstrictive response between patients with MJD and healthy controls. These results indicate that patients with MJD have reduced cutaneous sympathetic response, including severely impaired sudomotor functions and mildly affected vasomotor functions.     

Cognitive Deficits in Machado–Joseph Disease Correlate with Hypoperfusion of Visual System Areas

Cognitive and olfactory impairments have previously been demonstrated in patients with spinocerebellar ataxia type 3 (SCA3), also known as Machado–Joseph disease (MJD)—SCA3/MJD. We investigated changes in regional cerebral blood flow (rCBF) using single-photon emission computed tomography (SPECT) imaging in a cohort of Brazilian patients with SCA3/MJD. The aim of the present study was to evaluate the correlation among rCBF, cognitive deficits, and olfactory dysfunction in SCA3/MJD. Twenty-nine genetically confirmed SCA3/MJD patients and 25 control subjects were enrolled in the study. The severity of cerebellar symptoms was measured using the International Cooperative Ataxia Rating Scale and the Scale for the Assessment and Rating of Ataxia. Psychiatric symptoms were evaluated by the Hamilton Anxiety Scale and Beck Depression Inventory. The neuropsychological assessment consisted of Spatial Span, Symbol Search, Picture Completion, the Stroop Color Word Test, Trail Making Test (TMT), and Phonemic Verbal Fluency. Subjects were also submitted to odor identification evaluation using the 16-item Sniffin’ Sticks. SPECT was performed using ethyl cysteine dimer labeled with technetium-99m. SCA3/MJD patients showed reduced brain perfusion in the cerebellum, temporal, limbic, and occipital lobes compared to control subjects (pFDR <0.001). A significant positive correlation was found between the Picture Completion test and perfusion of the left parahippocampal gyrus and basal ganglia in the patient group as well as a negative correlation between the TMT part A and bilateral thalamus perfusion. The visuospatial system is affected in patients with SCA3/MJD and may be responsible for the cognitive deficits seen in this disease.     

Excessive fragmentary myoclonus in Machado–Joseph disease

ObjectiveMachado–Joseph disease (MJD) is a neurodegenerative disease which usually presents several clinical findings including cerebellar ataxia and other extracerebellar features, such as Parkinsonism, dystonia, peripheral neuropathy, and lower motor neuron disease. Some data have demonstrated a high frequency of sleep disorders in these patients, including excessive daytime sleepiness (EDS), insomnia, obstructive sleep apnea (OSA), rapid eye movement (REM) sleep behavior disorder (RBD), and restless legs syndrome (RLS). Herein, we aimed to describe the high frequency of excessive fragmentary myoclonus (EFM) in MJD.Materials and methodsWe recruited 44 patients with MJD and 44 healthy controls. All participants underwent an all-night polysomnography (PSG). EFM was evaluated and defined in accordance to the criteria of the American Academy of Sleep Medicine.ResultsHalf of the MJD patients (n = 22) had EFM diagnosed through PSG, though no healthy control participant presented this finding (P < .0001). In the MJD group, older participants and men had a higher frequency of EFM. There was no correlation between EFM and the following data: body mass index (BMI), apnea–hypopnea index (AHI), EDS, loss of atonia during REM sleep, periodic limb movements during sleep (PLMS), RLS, RBD, ataxia severity, the number of cytosine–adenine–guanine trinucleotide (CAG) repeats, disease duration, sleep efficiency, sleep fragmentation, and sleep stage percentages between patients with or without EFM.ConclusionEFM is highly prevalent in patients with MJD. Our study demonstrates that EFM must be included in the clinical spectrum of sleep disorders in MJD patients.     

Involvement of Onuf’s nucleus in Machado–Joseph disease: a morphometric and immunohistochemical study

Machado–Joseph disease (MJD) is an autosomal dominant neurodegenerative disease caused by an expansion of CAG repeats in the MJD1 gene, in which lower urinary tract dysfunction is known to be the most commonly encountered autonomic failure. However, it remains unclear whether Onuf’s nucleus (ON), which plays major roles in the micturition reflex and voluntary continence, degenerates during the disease process. In the present study, we conducted a morphometric and immunohistochemical study of ON, together with the lateral nuclear group (LNG) of the sacral anterior horns, in seven patients with MJD. When compared with controls, the number of lower motor neurons in both ON and LNG was significantly smaller in the MJD patients, the former being inversely correlated with the size of the expanded CAG repeats. Notably, MJD patients with a large CAG-repeat expansion showed an ON-predominant pattern of neuronal loss, while in the remaining patients, ON and LNG were affected to a similar degree, or rather an LNG-predominant pattern of neuronal loss was evident. Moreover, when adjusted for age, the degree of neuronal loss in both ON and LNG was significantly correlated with the extent of expansion of the CAG repeats. In MJD, the remaining lower motor neurons in ON often exhibited ataxin-3- or 1C2-immunoreactive (ir) neuronal intranuclear inclusions, while no pTDP-43-ir neuronal cytoplasmic inclusions were present in these neurons. In conclusion, the present findings strongly suggest that neuronal loss in ON, the degree of which is highly influenced by the extent of expansion of CAG repeats, is a consistent feature in MJD.     

Urinary symptoms and urodynamic findings in patients with Machado–Joseph disease

The study evaluated the prevalence of clinical and urodynamic findings in the lower urinary tract of patients with Machado–Joseph (MJ) disease. One hundred twenty-two patients were retrospectively evaluated; 17 (13.9%) presented lower urinary tract dysfunction, 10 of them were women. The average age was 41.6 years. Urgency was found in 15 patients and incontinence in nine. The urodynamic study showed detrusor overactivity in eight patients, areflexia in one, and four with normal detrusor contractility. Bladder sensitivity was abnormal in six, bladder capacity was decreased in one, urine flow decreased in 13, post-voiding residue was greater than 100 ml in nine. We could not find sphincter dyssynergia. The average cytosine–adenine–guanine (CAG) repetition was higher in patients with abnormal detrusor contraction (89.9) than in patients with normal urodynamics (68.2) (p = 0.03). There was no statistical significance when comparing the averages of replicates for people with and without urgency urinary incontinence (p = 0.27 and p = 0.5, respectively). The rate of lower urinary tract dysfunction in patients with MJ disease was around 14%. The urodynamic study showed predominance of detrusor overactivity and urgency as the most common symptom. We found an association between the total number of CAG repetitions and changes in detrusor contractility.     

Sleep disorders in Machado–Joseph disease: A dopamine transporter imaging study

ObjectivesSleep disorders, especially restless legs syndrome (RLS) and rapid eye movement sleep behavior disorder (RBD), are common in spinocerebellar ataxia type 3 or Machado–Joseph disease (MJD), and a possible underlying dopaminergic dysfunction is implicated. This study assessed the relationship between sleep disorders in MJD and dopamine transporter (DAT) densities.Patients and methodsTwenty-two patients with MJD and twenty healthy subjects were enrolled in this study. MJD patients underwent clinical sleep evaluation and polysomnography. SPECT with [^99mTc]-TRODAT-1, was performed in all subjects.ResultsDAT densities were significantly reduced in MJD group when compared to controls. No significant correlation was found between DAT densities and RLS or RBD in MJD.ConclusionOur study failed to demonstrate a clear correlation between sleep disorders and DAT densities in MJD patients, hence suggesting that extrastriatal and non-presynaptic dopamine pathways could be implicated in MJD-related sleep disorders.     

Sequence Analysis of 5′ Regulatory Regions of the Machado–Joseph Disease Gene (ATXN3)

Machado–Joseph disease (MJD) is a late-onset autosomal dominant neurodegenerative disorder, which is caused by a coding (CAG)_n expansion in the ATXN3 gene (14q32.1). The number of CAG repeats in the expanded alleles accounts only for 50 to 75 % of onset variance, the remaining variation being dependent on other factors. Differential allelic expression of ATXN3 could contribute to the explanation of different ages at onset in patients displaying similar CAG repeat sizes. Variation in 5′ regulatory regions of the ATXN3 gene may have the potential to influence expression levels and, ultimately, modulate the MJD phenotype. The main goal of this work was to analyze the extent of sequence variation upstream of the ATXN3 start codon. A fragment containing the core promoter and the 5′ untranslated region (UTR) was sequenced and analyzed in 186 patients and 59 controls (490 chromosomes). In the core promoter, no polymorphisms were observed. In the 5′ UTR, only one SNP (rs3814834) was found, but no improvements on the explanation of onset variance were observed, when adding its allelic state in a linear model. Accordingly, in silico analysis predicted that this SNP lays in a nonconserved position for CMYB binding. Therefore, no functional effect could be predicted for this variant.     

Neurophysiological Studies and Non-Motor Symptoms Prior to Ataxia in a Patient with Machado–Joseph Disease: Trying to Understand the Natural History of Brain Degeneration

Spinocerebellar ataxia type 3 or Machado–Joseph disease is the most common spinocerebellar ataxia. In this neurological disease, anatomical, physiological, clinical, and functional neuroimaging demonstrate a degenerative process besides the cerebellum. We performed neurophysiological and neuroimaging studies—polysomnography, transcranial sonography, vestibular-evoked myogenic potential, single-photon emission computed tomography (SPECT) with ^99mTc-TRODAT-1, and a formal neuropsychological evaluation in a patient with sleep complaints and positive testing for Machado–Joseph disease, without cerebellar atrophy, ataxia, or cognitive complaints. Polysomnography disclosed paradoxical high amplitude of submental muscle, characterizing REM sleep without atonia phenomenon. Transcranial sonography showed hyperechogenicity of the substantia nigra. There was an absence of vestibular-evoked myogenic potentials on both sides in the patient under study, in opposite to 20 healthy subjects. Brain imaging SPECT with ^99mTc-TRODAT-1 demonstrated a significant lower DAT density than the average observed in six healthy controls. Electroneuromyography was normal. Neuropsychological evaluation demonstrated visuospatial and memory deficits. Impairment of midbrain cholinergic and pontine noradrenergic systems, dysfunction of the pre-synaptic nigrostriatal system, changes in echogenicity of the substantia nigra, and damage to vestibulo-cervical pathways are supposed to occur previous to cerebellar involvement in Machado–Joseph disease.     

Altered Heart Rate Control in Response to Postural Change in Patients with Machado–Joseph Disease (SCA3)

To assess heart rate (HR) regulation in Machado–Joseph disease (MJD), we evaluated HR variability at rest and the initial HR response to standing suddenly in 13 MJD patients and 26 normal control subjects. A head-up tilt (HUT) test involving the monitoring of blood pressure, HR, and cerebral oxy/deoxyhemoglobin concentration was also performed in each participant. There was no significant difference in HR variability at rest between the two groups, but the transient HR rise just after standing suddenly in the MJD group was significantly less than that in the control group (p < 0.01). The HUT test, where each participant was gradually tilted upward, induced a significantly greater HR increase in the MJD group compared with the controls (p < 0.01), while there were no significant differences in the blood pressure and cerebral oxygenation changes between the two groups. In our MJD study, the transient HR rise just after standing suddenly was diminished, and HR markedly increased during sustained orthostatic stress.     

Selective occurrence of TDP-43-immunoreactive inclusions in the lower motor neurons in Machado–Joseph disease

Pathological transactivation-responsive DNA-binding protein 43 (TDP-43) has been identified as a component of ubiquitinated inclusions in frontotemporal lobar degeneration with motor neuron disease, as well as in sporadic and some forms of familial amyotrophic lateral sclerosis. To clarify whether pathological TDP-43 is present in other neurodegenerative diseases involving the motor neuron system, we immunohistochemically examined the brain and spinal cord affected by two CAG repeat (polyglutamine) diseases, Machado–Joseph disease (MJD) and spinal and bulbar muscular atrophy (SBMA), using polyclonal antibody against TDP-43. In all the MJD cases, TDP-43-immunoreactive (ir) neuronal cytoplasmic inclusions (NCIs), although few in number, were found only in the lower motor neurons in the brainstem and spinal cord. TDP-43-ir NCIs appeared as linear wisp-like, skein-like, or thick, somewhat rod-like bodies. These inclusions were also visualized with antibodies against phosphoserines 409 and 410 of TDP-43, and ubiquitin, but were not recognized by antibody against expanded polyglutamine stretches or ataxin-3. The ultrastructure of the TDP-43-ir NCIs was similar to that of the inclusions seen in sporadic ALS, consisting of bundles of parallel filaments. None of the SBMA cases showed abnormal TDP-43 immunoreactivity in any of the regions examined. Immunoblot analysis failed to recognize hyperphosphorylated TDP-43 at ~23 kDa in two MJD cases examined. However, the immunohistochemical findings strongly suggested that in MJD, in addition to the polyglutamine-dependent disease process, TDP-43-related pathogenesis is associated with degeneration and death of the lower motor neurons.     

Parkinson’s Disease Genetic Loci in Rapid Eye Movement Sleep Behavior Disorder

Journal of Molecular Neuroscience - Rapid eye movement (REM) sleep behavior disorder (RBD) is a prodromal condition for Parkinson’s disease (PD) and other synucleinopathies, which often...     

Eye Movement and Visual Search: Are There Elementary Abnormalities in Autism?

Although atypical eye gaze is commonly observed in autism, little is known about underlying oculomotor abnormalities. Our review of visual search and oculomotor systems in the healthy brain suggests that relevant networks may be partially impaired in autism, given regional abnormalities known from neuroimaging. However, direct oculomotor evidence for autism remains limited. This gap is critical since oculomotor abnormalities might play a causal role in functions known to be impaired in autism, such as imitation and joint attention. We integrate our oculomotor review into a developmental approach to language impairment related to nonverbal prerequisites. Oculomotor abnormalities may play a role as a sensorimotor defect at the root of impairments in later developing functional systems, ultimately resulting in sociocommunicative deficits.     

Parkinson Disease and Sleep: Sleep–Wake Changes in the Premotor Stage of Parkinson Disease; Impaired Olfaction and Other Prodromal Features

Parkinson disease (PD) has a premotor stage where neurodegeneration occurs before parkinsonism becomes apparent. Identification of individuals at this stage provides an opportunity to study early disease progression and test disease-modifying interventions. Hyposmia, constipation, depression and hypersomnia are part of this premotor phase and predictive of future development of PD. However, these features are common in the general population, and they are most often the result of causes other than incipient PD. In contrast, most individuals with idiopathic REM sleep behavior disorder (IRBD) eventually develop PD and other synucleinopathies. IRBD individuals with hyposmia, substantia nigra hyperechogenicity, and abnormal striatal dopamine transporter imaging findings have increased short-term risk of developing a synucleinopathy. IRBD is an optimal target to test disease-modifying agents in the PD prodromal phase. Serial dopamine transporter imaging, but not olfactory tests, may serve to monitor the disease process in future disease-modifying trials in IRBD.