Regulation of adaptive growth decisions via phosphorylation of the TRAPPII complex in Arabidopsis

Plants often adapt to adverse or stress conditions via differential growth. The trans-Golgi network (TGN) has been implicated in stress responses, but it is not clear in what capacity it mediates adaptive growth decisions. In this study, we assess the role of the TGN in stress responses by exploring the previously identified interactome of the Transport Protein Particle II (TRAPPII) complex required for TGN structure and function. We identified physical and genetic interactions between AtTRAPPII and shaggy-like kinases (GSK3/AtSKs) and provided in vitro and in vivo evidence that the TRAPPII phosphostatus mediates adaptive responses to abiotic cues. AtSKs are multifunctional kinases that integrate a broad range of signals. Similarly, the AtTRAPPII interactome is vast and considerably enriched in signaling components. An AtSK-TRAPPII interaction would integrate all levels of cellular organization and instruct the TGN, a central and highly discriminate cellular hub, as to how to mobilize and allocate resources to optimize growth and survival under limiting or adverse conditions.

Regulation of adaptive growth decisions via phosphorylation of the TRAPPII complex in Arabidopsis

Plants often adapt to adverse or stress conditions via differential growth. The trans-Golgi Network (TGN) has been implicated in stress responses, but it is not clear in what capacity it mediates adaptive growth decisions. In this study, we assess the role of the TGN in stress responses by exploring the interactome of the Transport Protein Particle II (TRAPPII) complex, required for TGN structure and function. We identified physical and genetic interactions between TRAPPII and shaggy-like kinases (GSK3/AtSKs). Kinase assays and pharmacological inhibition provided in vitro and in vivo evidence that AtSKs target the TRAPPII-specific subunit AtTRS120/TRAPPC9. GSK3/AtSK phosphorylation sites in AtTRS120/TRAPPC9 were mutated, and the resulting AtTRS120 phosphovariants subjected to a variety of single and multiple stress conditions in planta . The non-phosphorylatable TRS120 mutant exhibited enhanced adaptation to multiple stress conditions and to osmotic stress whereas the phosphomimetic version was less resilient. Higher order inducible trappii atsk mutants had a synthetically enhanced defect in root gravitropism. Our results suggest that the TRAPPII phosphostatus mediates adaptive responses to abiotic cues. AtSKs are multifunctional kinases that integrate a broad range of signals. Similarly, the TRAPPII interactome is vast and considerably enriched in signaling components. An AtSK-TRAPPII interaction would integrate all levels of cellular organization and instruct the TGN, a central and highly discriminate cellular hub, as to how to mobilize and allocate resources to optimize growth and survival under limiting or adverse conditions.

Unified Workflow for the Rapid and In-Depth Characterization of Bacterial Proteomes

Bacteria are the most abundant and diverse organisms among the kingdoms of life. Due to this excessive variance, finding a unified, comprehensive, and safe workflow for quantitative bacterial proteomics is challenging. In this study, we have systematically evaluated and optimized sample preparation, mass spectrometric data acquisition, and data analysis strategies in bacterial proteomics. We investigated workflow performances on six representative species with highly different physiologic properties to mimic bacterial diversity. The best sample preparation strategy was a cell lysis protocol in 100% trifluoroacetic acid followed by an in-solution digest. Peptides were separated on a 30-min linear microflow liquid chromatography gradient and analyzed in data-independent acquisition mode. Data analysis was performed with DIA-NN using a predicted spectral library. Performance was evaluated according to the number of identified proteins, quantitative precision, throughput, costs, and biological safety. With this rapid workflow, over 40% of all encoded genes were detected per bacterial species. We demonstrated the general applicability of our workflow on a set of 23 taxonomically and physiologically diverse bacterial species. We could confidently identify over 45,000 proteins in the combined dataset, of which 30,000 have not been experimentally validated before. Our work thereby provides a valuable resource for the microbial scientific community. Finally, we grew Escherichia coli and Bacillus cereus in replicates under 12 different cultivation conditions to demonstrate the high-throughput suitability of the workflow. The proteomic workflow we present in this manuscript does not require any specialized equipment or commercial software and can be easily applied by other laboratories to support and accelerate the proteomic exploration of the bacterial kingdom.

Enzyme expression kinetics by Escherichia coli during transition from rich to minimal media depends on proteome reserves

Bacterial fitness depends on adaptability to changing environments. In rich growth medium, which is replete with amino acids, Escherichia coli primarily expresses protein synthesis machineries, which comprise ~40% of cellular proteins and are required for rapid growth. Upon transition to minimal medium, which lacks amino acids, biosynthetic enzymes are synthesized, eventually reaching ~15% of cellular proteins when growth fully resumes. We applied quantitative proteomics to analyse the timing of enzyme expression during such transitions, and established a simple positive relation between the onset time of enzyme synthesis and the fractional enzyme 'reserve' maintained by E. coli while growing in rich media. We devised and validated a coarse-grained kinetic model that quantitatively captures the enzyme recovery kinetics in different pathways, solely on the basis of proteomes immediately preceding the transition and well after its completion. Our model enables us to infer regulatory strategies underlying the 'as-needed' gene expression programme adopted by E. coli.

Merits of Diazirine Photo-Immobilization for Target Profiling of Natural Products and Cofactors

Finding the targets of natural products is of key importance in both chemical biology and drug discovery, and deconvolution of cofactor interactomes contributes to the functional annotation of the proteome. Identifying the proteins that underlie natural compound activity in phenotypic screens helps to validate the respective targets and, potentially, expand the druggable proteome. Here, we present a generally applicable protocol for the photoactivated immobilization of unmodified and microgram quantities of natural products on diazirine-decorated beads and their use for systematic affinity-based proteome profiling. We show that among 31 molecules of very diverse reported activity and biosynthetic origin, 25 could indeed be immobilized. Dose-response competition binding experiments using lysates of human or bacterial cells followed by quantitative mass spectrometry recapitulated targets of 9 molecules with <100 μM affinity. Among them, immobilization of coenzyme A produced a tool to interrogate proteins containing a HotDog domain. Surprisingly, immobilization of the cofactor flavin adenine dinucleotide (FAD) led to the identification of nanomolar interactions with dozens of RNA-binding proteins.

Impact of Modified Atmospheres on Growth and Metabolism of Meat-Spoilage Relevant Photobacterium spp. as Predicted by Comparative Proteomics

Modified atmosphere packaging (MAP) is a common strategy to selectively prevent the growth of certain species of meat spoiling bacteria. This study aimed to determine the impact of high oxygen MAP (70% O₂, 30% CO₂, red and white meats) and oxygen-free MAP (70% N₂, 30% CO₂, also white meat and seafood) on preventing the growth of spoiling photobacteria on meat. Growth of Photobacterium carnosum and P. phosphoreum was monitored in a meat simulation media under different gas mixtures of nitrogen, oxygen, and carbon dioxide, and samples were taken during exponential growth for a comparative proteomic analysis. Growth under air atmosphere appears optimal, particularly for P. carnosum. Enhanced protein accumulation affected energy metabolism, respiration, oxygen consuming reactions, and lipid usage. However, all the other atmospheres show some degree of growth reduction. An increase in oxygen concentration leads to an increase in enzymes counteracting oxidative stress for both species and enhancement of heme utilization and iron-sulfur cluster assembly proteins for P. phosphoreum. Absence of oxygen appears to switch the metabolism toward fermentative pathways where either ribose (P. phosphoreum) or glycogen (P. carnosum) appear to be the preferred substrates. Additionally, it promotes the use of alternative electron donors/acceptors, mainly formate and nitrate/nitrite. Stress response is manifested as an enhanced accumulation of enzymes that is able to produce ammonia (e.g., carbonic anhydrase, hydroxylamine reductase) and regulate osmotic stress. Our results suggest that photobacteria do not sense the environmental levels of carbon dioxide, but rather adapt to their own anaerobic metabolism. The regulation in presence of carbon dioxide is limited and strain-specific under anaerobic conditions. However, when oxygen at air-like concentration (21%) is present together with carbon dioxide (30%), the oxidative stress appears enhanced compared to air conditions (very low carbon dioxide), as explained if both gases have a synergistic effect. This is further supported by the increase in oxygen concentration in the presence of carbon dioxide. The atmosphere is able to fully inhibit P. carnosum, heavily reduce P. phosphoreum growth in vitro, and trigger diversification of energy production with higher energetic cost, highlighting the importance of concomitant bacteria for their growth on raw meat under said atmosphere.

Spotlight on alternative frame coding: Two long overlapping genes in Pseudomonas aeruginosa are translated and under purifying selection

The existence of overlapping genes (OLGs) with significant coding overlaps revolutionizes our understanding of genomic complexity. We report two exceptionally long (957 nt and 1536 nt), evolutionarily novel, translated antisense open reading frames (ORFs) embedded within annotated genes in the pathogenic Gram-negative bacterium Pseudomonas aeruginosa. Both OLG pairs show sequence features consistent with being genes and transcriptional signals in RNA sequencing. Translation of both OLGs was confirmed by ribosome profiling and mass spectrometry. Quantitative proteomics of samples taken during different phases of growth revealed regulation of protein abundances, implying biological functionality. Both OLGs are taxonomically restricted, and likely arose by overprinting within the genus. Evidence for purifying selection further supports functionality. The OLGs reported here, designated olg1 and olg2, are the longest yet proposed in prokaryotes and are among the best attested in terms of translation and evolutionary constraint. These results highlight a potentially large unexplored dimension of prokaryotic genomes.

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Two novel, very long, overlapping genes were found in Pseudomonas aeruginosa

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Both overlapping genes, olg1 and olg2, are transcribed, translated, and regulated

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Mass spectrometry verifies translation of the overlapping and their mother genes

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Both overlapping genes are taxonomically restricted, but under purifying selection

Comparative Proteomics Reveals the Anaerobic Lifestyle of Meat-Spoiling Pseudomonas Species

The ability of certain Pseudomonas (P.) species to grow or persist in anoxic habitats by either denitrification, acetate fermentation, or arginine fermentation has been described in several studies as a special property. Previously, we had isolated strains belonging to the species P. lundensis, P. weihenstephanensis, and P. fragi from anoxic modified atmosphere packaged (MAP) minced beef and further proved their anaerobic growth in vitro on agar plates. This follow-up study investigated the anaerobic growth of two strains per respective species in situ on inoculated chicken breast filet under 100% N₂ modified atmosphere. We were able to prove anaerobic growth of all six strains on chicken breast filet with cell division rates of 0.2–0.8/day. Furthermore, we characterized the anaerobic metabolic lifestyle of these Pseudomonas strains by comparative proteomics, upon their cultivation in meat simulation media, which were constantly gassed with either air or 100% N₂ atmospheres. From these proteomic predictions, and respective complementation by physiological experiments, we conclude that the Pseudomonas strains P. fragi, P. weihenstephanensis, P. lundensis exhibit a similar anaerobic lifestyle and employ arginine fermentation via the arginine deiminase (ADI) pathway to grow anaerobically also on MAP meats. Furthermore, glucose fermentation to ethanol via the ED-pathway is predicted to enable long term survival but no true growth, while respiratory growth with nitrate as alternative electron acceptor or glucose fermentation to acetate could be excluded due to absence of essential genes. The citric acid cycle is partially bypassed by the glyoxylate shunt, functioning as the gluconeogenetic route without production of NADH₂ under carbon limiting conditions as e.g., in packaged meats. Triggered by an altered redox balance, we also detected upregulation of enzymes involved in protein folding as well as disulfide bonds isomerization under anoxic conditions as a counteracting mechanism to reduce protein misfolding. Hence, this study reveals the mechanisms enabling anaerobic grow and persistence of common meat-spoiling Pseudomonas species, and further complements the hitherto limited knowledge of the anaerobic lifestyle of Pseudomonas species in general.

Interactions between Transport Protein Particle (TRAPP) complexes and Rab GTPases in Arabidopsis

Transport Protein Particle II (TRAPPII) is essential for exocytosis, endocytosis, protein sorting and cytokinesis. In spite of a considerable understanding of its biological role, little information is known about Arabidopsis TRAPPII complex topology and molecular function. In this study, independent proteomic approaches initiated with TRAPP components or Rab-A GTPase variants converge on the TRAPPII complex. We show that the Arabidopsis genome encodes the full complement of 13 TRAPPC subunits, including four previously unidentified components. A dimerization model is proposed to account for binary interactions between TRAPPII subunits. Preferential binding to dominant negative (GDP-bound) versus wild-type or constitutively active (GTP-bound) RAB-A2a variants discriminates between TRAPPII and TRAPPIII subunits and shows that Arabidopsis complexes differ from yeast but resemble metazoan TRAPP complexes. Analyzes of Rab-A mutant variants in trappii backgrounds provide genetic evidence that TRAPPII functions upstream of RAB-A2a, allowing us to propose that TRAPPII is likely to behave as a guanine nucleotide exchange factor (GEF) for the RAB-A2a GTPase. GEFs catalyze exchange of GDP for GTP; the GTP-bound, activated, Rab then recruits a diverse local network of Rab effectors to specify membrane identity in subsequent vesicle fusion events. Understanding GEF-Rab interactions will be crucial to unravel the co-ordination of plant membrane traffic.

Features of probable multiple system atrophy patients identified among 4770 patients with parkinsonism enrolled in the multicentre registry of the German Competence Network on Parkinson’s disease

We identified 221 patients with probable multiple system atrophy (MSA) among 4770 patients enrolled in the multicentre registry of the German Competence Network on Parkinson's disease (PD) according to the established consensus criteria to characterize their clinical presentation. Analyses of more than 100 recorded clinical items revealed several specifics: I) 50% of patients with probable MSA had asymmetry of symptoms at disease onset and tremor at rest was present in 25%; II) a positive response to levodopa was recorded in 51% of patients identified initially with severe autonomic failure and cerebellar ataxia; III) a positive family history was recorded in 11% (n = 23), two of these patients were identified with spinocerebellar ataxia type 3 (SCA3). Thus asymmetry of symptoms, tremor at rest and a positive response to levodopa are not as specific for idiopathic PD as believed previously. Patients with SCA3 may present with the clinical features of MSA.

Voxel-based morphometry and voxel-based relaxometry in multiple system atrophy-a comparison between clinical subtypes and correlations with clinical parameters

Multiple system atrophy (MSA) is a neurodegenerative disease affecting basal ganglia, brainstem, cerebellum, and intermediolateral cell columns of the spinal cord. Clinically, a cerebellar (MSA-C) and a parkinsonian variant of MSA (MSA-P) are distinguished. We used voxel-based morphometry (VBM) and voxel-based relaxometry (VBR) in 48 MSA patients (32 MSA-C, 16 MSA-P) and 46 controls. In MSA-C, VBM revealed gray matter loss in cerebellum, right thalamus, both putamina and several cortical regions including insular cortex. Gray matter loss in the cerebellum and insular cortex was correlated with disease duration and severity. There was white matter loss in the brainstem, which was correlated with disease duration and severity. VBR analysis in MSA-C showed decreased relaxation rate R2 in cerebellum, pontine brainstem and cortical regions including insular cortex. In MSA-P, gray matter was reduced in cerebellum, dorsal midbrain, both putamina, and several cortical regions including insular cortex. A correlation with disease duration and severity was detected only for some small cortical areas. Direct comparison of MSA-C and MSA-P showed differences only in infratentorial brain regions where structural abnormalities were more pronounced in MSA-C than in MSA-P. In MSA-C, there was a stronger reduction of gray matter in the basal parts of the cerebellum, of white matter in the brainstem and of the relaxation rate R2 in the cerebellum and brainstem.

Saccade Velocity as a Surrogate Disease Marker in Spinocerebellar Ataxia Type 2

We measured in 82 spinocerebellar ataxia type 2 (SCA2) patients and in 80 controls maximal saccade velocity (MSV) and correlated it to polyglutamine expansion size and disease duration. MSV is strongly decreased in SCA2 patients and is influenced mostly by polyglutamine size.

The European Multiple System Atrophy-Study Group (EMSA-SG)

Introduction. The European Multiple System Atrophy-Study Group (EMSA-SG) is an academic network comprising 23 centers across Europe and Israel that has constituted itself already in January 1999. This international forum of established experts under the guidance of the University Hospital of Innsbruck as coordinating center is supported by the 5th framework program of the European Union since March 2001 (QLK6-CT-2000-00661). Objectives. Primary goals of the network include (1) a central Registry for European multiple system atrophy (MSA) patients, (2) a decentralized DNA Bank, (3) the development and validation of the novel Unified MSA Rating Scale (UMSARS), (4) the conduction of a Natural History Study (NHS), and (5) the planning or implementation of interventional therapeutic trials. Methods. The EMSA-SG Registry is a computerized data bank localized at the coordinating centre in Innsbruck collecting diagnostic and therapeutic data of MSA patients. Blood samples of patients and controls are recruited into the DNA Bank. The UMSARS is a novel specific rating instrument that has been developed and validated by the EMSA-SG. The NHS comprises assessments of basic anthropometric data as well as a range of scales including the UMSARS, Unified Parkinson's Disease Rating Scale (UPDRS), measures of global disability, Red Flag list, MMSE (Mini Mental State Examination), quality of live measures, i.e. EuroQoL 5D (EQ-5D) and Medical Outcome Study Short Form (SF-36) as well as the Beck Depression Inventory (BDI). In a subgroup of patients dysautonomic features are recorded in detail using the Queen Square Cardiovascular Autonomic Function Test Battery, the Composite Autonomic Symptom Scale (COMPASS) and measurements of residual urinary volume. Most of these measures are repeated at 6-monthly follow up visits for a total study period of 24 months. Surrogate markers of the disease progression are identified by the EMSA-SG using magnetic resonance and diffusion weighted imaging (MRI and DWI, respectively). Results. 412 patients have been recruited into the Registry so far. Probable MSA-P was the most common diagnosis (49% of cases). 507 patients donated DNA for research. 131 patients have been recruited into the NHS. There was a rapid deterioration of the motor disorder (in particular akinesia) by 26.1% of the UMSARS II, and - to a lesser degree - of activities of daily living by 16.8% of the UMSARS I in relation to the respective baseline scores. Motor progression was associated with low motor or global disability as well as low akinesia or cerebellar subscores at baseline. Mental function did not deteriorate during this short follow up period. Conclusion. For the first time, prospective data concerning disease progression are available. Such data about the natural history and prognosis of MSA as well as surrogate markers of disease process allow planning and implementation of multi-centre phase II/III neuroprotective intervention trials within the next years more effectively. Indeed, a trial on growth hormone in MSA has just been completed, and another on minocycline will be completed by the end of this year.

L-carnitine and creatine in Friedreich's ataxia. A randomized, placebo-controlled crossover trial

Impaired oxidative phosphorylation is a crucial factor in the pathogenesis of Friedreich's ataxia (FA). L-carnitine and creatine are natural compounds that can enhance cellular energy transduction. We performed a placebo-controlled triple-phase crossover trial of L-carnitine (3 g/d) and creatine (6.75 g/d) in 16 patients with genetically confirmed FA. Primary outcome measures were mitochondrial ATP production measured as phosphocreatine recovery by 31Phosphorus magnetic resonance spectroscopy, neurological deficits assessed by the international co-operative ataxia rating scale and cardiac hypertrophy in echocardiography. After 4 months on L-carnitine phosphocreatine recovery was improved compared to baseline (p<0.03, t-test) but comparison to placebo and creatine effects did not reach significance (p=0.06, F-test). Ataxia rating scale and echocardiographic parameters remained unchanged. Creatine had no effect in FA patients. L-carnitine is a promising substance for the treatment of FA patients, and larger trials are warranted.

Probable multiple system atrophy in a German family

Multiple system atrophy (MSA) is a neurodegenerative disorder of unknown aetiology. A possible underlying genetic component has not yet been identified. A family is reported with phenotypic MSA and probable autosomal dominant inheritance. The patients presented initially with either parkinsonian or cerebellar signs, and developed severe autonomic failure and typical atrophy of the brain stem and cerebellum in the course of the disease.

Prevalence of antigliadin antibodies in ataxia patients

We determined antigliadin antibodies in 95 ataxia patients and 73 controls. Antibodies were positive in 8% of the controls, 19% of patients with sporadic ataxia, 8% of patients with recessive ataxia, and 15% of patients with dominant ataxia. Statistical comparison using chi(2) statistics did not reveal significant differences between the groups. Although we found a trend toward a higher prevalence of antigliadin antibodies in patients with sporadic ataxia and dominant ataxia, our data do not support an association of ataxia with antigliadin antibodies.

The aetiology of sporadic adult-onset ataxia

The nosology and aetiology of sporadic adult-onset ataxia are poorly understood. The aim of the present study was to answer the following questions: (i) How many sporadic ataxia patients have a genetic cause? (ii) How many sporadic ataxia patients suffer from multiple system atrophy (MSA)? (iii) Is there a specific association between sporadic ataxia and serum anti-glutamic acid decarboxylase (GAD) or antigliadin antibodies? and (iv) What are the clinical features of patients with unexplained sporadic ataxia? The study was performed in 112 patients who met the following inclusion criteria: (i) progressive ataxia; (ii) onset after 20 years; (iii) informative and negative family history (no similar disorders in first- and second-degree relatives; parents older than 50 years); and (iv) no established symptomatic cause. Thirty-two patients (29%) met the clinical criteria of possible (7%) or probable (22%) MSA. The Friedreich's ataxia mutation was found in five patients (4%), the spinocerebellar ataxia (SCA) 2 mutation in one (1%), the SCA3 mutation in two (2%) and the SCA6 mutation in seven (6%). The disease remained unexplained in 65 patients (58%). We did not detect anti-GAD antibodies in any of our patients. Antigliadin antibodies were present in 14 patients, 10 patients with unexplained ataxia (15%) and 4 patients with an established diagnosis (9%). Patients with unexplained sporadic ataxia had a median disease onset of 56.0 years. Decreased vibration sense (62%), decreased or absent ankle reflexes (40%), increased ankle reflexes (39%), dysphagia (38%) and extensor plantar responses and/or spasticity (34%) were the most frequent extracerebellar symptoms. Compared with MSA, disease progression was significantly slower.

Restless legs syndrome in spinocerebellar ataxia types 1, 2, and 3

To identify the prevalence and determinants of restless legs syndrome (RLS) in spinocerebellar ataxia (SCA) we studied 58 patients with a molecular diagnosis of SCA1, SCA2 and SCA3. Data on the symptoms of RLS were collected by a standardized questionnaire, and RLS was diagnosed when patients met the four minimal criteria of the syndrome as recently defined by an international study group. In addition, we studied the relationship between RLS and age, age at ataxia onset, CAG repeat length, and nerve conduction and evoked potentials data. RLS was significantly more frequent in SCA patients than in controls (28% vs. 10%). Age at RLS onset in SCA was 49.0 +/- 10.9 years. There were no significant differences in nerve conduction or evoked potentials between RLS and non-RLS SCA patients. The probability of developing RLS increased with age but not with CAG repeat length or higher age of ataxia onset. The data provide evidence that patients with SCA1, SCA2 and SCA3 are per se more susceptible to RLS than non-affected individuals. The probability of developing RLS is related principally to the period over which the CAG repeat mutation exerts its effect and not to CAG repeat length or age of ataxia onset.

Nerve conduction studies in multiple system atrophy

To study the frequency and severity of peripheral neuropathy in multiple system atrophy (MSA), we performed nerve conduction studies in 42 MSA patients suffering from either cerebellar MSA (MSA-C) or parkinsonian MSA (MSA-P). Abnormal nerve conduction was present in 24% of the patients. Abnormalities were significantly more frequent in MSA-P (43%) compared to MSA-C (14%). Motor nerve conduction velocities were reduced in 4% of the MSA-C and in 7% of the MSA-P patients. Abnormal compound muscle action potentials were more frequent in MSA-P (29% versus 7% in MSA-C) pointing to a more pronounced loss of motor axons in this subgroup. Sensory nerve conduction velocities were abnormal in 4% of the MSA-C and 14% of the MSA-P patients, and mean sensory nerve action potentials were normal in all MSA-C and reduced in 7% of the MSA-P patients. The data provide evidence that the peripheral nervous system is differentially affected in MSA-C and MSA-P.

Evoked potentials in multiple system atrophy (MSA)

OBJECTIVES

To study the involvement of pyramidal tracts and sensory pathways in multiple system atrophy (MSA).

MATERIALS AND METHODS

Evoked potential studies were performed in 45 MSA patients suffering from either MSA of cerebellar type (MSA-C) or MSA of parkinsonian type (MSA-P).

RESULTS

Motor evoked potentials were normal in all MSA patients, whereas visual and somatosensory evoked potential abnormalities were found in about 40% of the MSA patients with no significant difference between the cerebellar (MSA-C) and parkinsonian (MSA-P) subgroup. Abnormal latencies of wave III in brainstem auditory evoked potentials were significantly more frequent in MSA-C.

CONCLUSIONS

Abnormalities of somatosensory, visual and auditory evoked potentials are frequent findings in MSA, whereas abnormal motor evoked potentials are not a characteristic feature of the disease.

Autosomal dominant cerebellar ataxia type I: oculomotor abnormalities in families with SCA1, SCA2, and SCA3

Forty-six patients suffering from autosomal dominant cerebellar ataxia type I (ADCA I) underwent to a genotype-phenotype correlation analysis by molecular genetic assignment to the spinocerebellar ataxia type 1, 2, or 3 (SCA1, SCA2, SCA3) genetic locus and electro-oculography. Oculomotor deficits that are attributed to dysfunction of cerebellar structures occurred in all three mutations without major differences between the groups. Gaze-evoked nystagmus, however, was not found to be associated with SCA2. Square wave jerks were exclusively observed in SCA3. The gain in vestibulo-ocular reflex was significantly impaired in SCA3 and SCA1. In SCA3 the severity of vestibular impairment increased with CAG repeat length. Severe saccade slowing was a highly characteristic feature of SCA2. In SCA3 saccade velocity was normal to mildly reduced while SCA1 fell into an intermediate range. The present data show that each mutation is associated with a distinct syndrome of oculomotor deficits. Reduced saccade velocity and the absence of both square-wave jerks and gaze-evoked nystagmus allow one SCA2 to be distinguished from SCA3 patients in almost all cases. The eye movement disorder of SCA1 patients, however, overlaps with both SCA2 and SCA3.

Cognitive deficits in spinocerebellar ataxia 2

This is one of the first studies assessing the pattern of cognitive impairment in spinocerebellar ataxia 2 (SCA2). Cognitive function was studied in 17 patients with genetically confirmed SCA2 and 15 age- and IQ- matched controls using a neuropsychological test battery comprising tests for IQ, attention, verbal and visuospatial memory, as well as executive functions. Twenty-five percent of the SCA2 subjects showed evidence of dementia. Even in non-demented SCA2 subjects, there was evidence of verbal memory and executive dysfunction. Tests of visuospatial memory and attention were not significantly impaired in the non-demented group compared with controls. There was no relationship between test performance and motor disability, repeat length or age of onset, while disease duration was shown to be inversely correlated with two tests reflecting the progression of cognitive deficits during the course of the disease. Intellectual impairment should therefore not be interpreted as a secondary effect of progressive motor disability, but represents an important and independent part of the SCA2 phenotype.

Cerebellar ataxia with glutamic acid decarboxylase autoantibodies

Degenerative cerebellar ataxia with autoantibodies against glutamic acid decarboxylase (GAD) is a rare disorder and may represent a subset of ataxias previously classified as idiopathic. The authors report a patient with progressive cerebellar ataxia, insulin-dependent diabetes mellitus, and GAD antibodies who responded to i.v. immunoglobulins.

Age related axonal neuropathy in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD)

To identify determinants of peripheral involvement in spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) the influence of CAG repeat length, age of onset, disease duration and age on the results of nerve conduction studies was analysed in 58 patients with SCA3/MJD. Patients with SCA3/MJD showed marked reduction of compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes indicating axonal neuropathy of both motor and sensory fibres. In addition, there was moderate slowing of nerve conduction suggestive of mild peripheral demyelination. Multivariate regression showed that CMAP and SNAP amplitudes decreased with age, but were not affected by CAG repeat length, age of onset, or disease duration. The age related decline of CMAP and SNAP amplitudes in SCA3/MJD was greater than in normal subjects. The data suggest that the degree of peripheral damage in SCA3/MJD does not depend on CAG repeat length, age of onset, or disease duration, but is mainly related to the time period over which the SCA3/MJD mutation exerts its effect.

Magnetic resonance imaging-based volumetry differentiates idiopathic Parkinson's syndrome from multiple system atrophy and progressive supranuclear palsy

By using three-dimensional magnetic resonance imaging-based volumetry, we studied atrophy of the caudate nucleus, putamen, brainstem, and cerebellum in patients with idiopathic Parkinson's syndrome (IPS, n = 11), progressive supranuclear palsy (PSP, n = 6), and multiple system atrophy with predominant parkinsonism (MSA-P, n = 12) or ataxia (MSA-C, n = 17). Patients were compared with a total of 46 controls, of whom 16 were age matched. Mean striatal, cerebellar, and brainstem volumes were normal in patients with IPS. We found significant reductions in mean striatal and brainstem volumes in patients with MSA-P, MSA-C, and PSP, whereas patients with MSA-C and MSA-P also showed a reduction in cerebellar volume. On an individual basis, volumes of structures in patients with MSA and PSP showed an extensive overlap with the normal range with the exception of brainstem volumes in patients with MSA-C. Therefore, groups could not be discriminated on the basis of individual structure volumetry. Application of stepwise discriminant analysis, however, allowed discrimination of all 12 patients with MSA-P, 15 of 17 patients with MSA-C, and 5 of 6 patients with PSP from the normal and IPS cohorts. However, patients with IPS could not be separated from controls and patients with MSA-P could not be separated from patients with PSP. In conclusion, total intracranial volume-normalized magnetic resonance imaging-based volumetric measurements provide a sensitive marker to discriminate typical and atypical parkinsonism.

Autosomal dominant cerebellar ataxia type I. MRI-based volumetry of posterior fossa structures and basal ganglia in spinocerebellar ataxia types 1, 2 and 3

Twenty-six patients suffering from autosomal dominant cerebellar ataxia type I were subjected to a genotype-phenotype correlation analysis using molecular genetic assignment to the genetic loci for spinocerebellar ataxia type 1, 2 or 3 (SCA1, SCA2, SCA3) and MRI-based volumetry of posterior fossa structures and basal ganglia nuclei. There was significant atrophy of the cerebellum and brainstem in all three SCA mutations compared with a group of 31 age- and sex-matched controls. Comparison between the SCA groups showed that cerebellar and brainstem atrophy was more severe in SCA2 than in SCA1 and SCA3. Putaminal and caudate volume was reduced only in SCA3, but not in SCA1 and SCA2. A set of three morphological criteria was defined that enabled us to assign all SCA2 and SCA3 patients correctly to the underlying genotype. In contrast, these criteria did not distinguish SCA1 from SCA2 and SCA3. Regression analysis failed to reveal a significant association between CAG repeat length and the volumes of the respective brain structures in any of the SCA mutant types. The present data provide in vivo evidence that SCA2 and SCA3 lead to distinct patterns of brain atrophy, while the atrophy changes in SCA1 overlap with both SCA2 and SCA3.

The natural history of degenerative ataxia: a retrospective study in 466 patients

The aim of the present study was (i) to compare disease progression and survival in different types of degenerative ataxia, and (ii) to identify variables that may modify the rate of disease progression. We included patients suffering from Friedreich's ataxia (FRDA, n = 83), early onset cerebellar ataxia (EOCA, n = 30), autosomal dominant cerebellar ataxia (ADCA) type I (ADCA-I, n = 273), ADCA-III (n = 13) and multiple system atrophy (MSA, n = 67). Molecular genetic testing allowed us to assign 202 ADCA-I patients to one of the following subgroups: spinocerebellar ataxia type I (SCAI, n = 36), SCA2 (n = 56) and SCA3 (n = 110). To assess disease progression we defined the following disease stages: stage 0 = no gait difficulties; stage 1 = disease onset, as defined by onset of gait difficulties; stage 2 = loss of independent gait; stage 3 = confinement to wheelchair; stage 4 = death. Disease progression was most rapid in MSA, intermediate in FRDA, ADCA-I and ADCA-III and slowest in EOCA. The rate of progression was similar in SCA1, SCA2 and SCA3. The CAG repeat length was a significant risk factor for faster progression in SCA2 and SCA3, but not in SCA1. In FRDA, the time until confinement to wheelchair was shorter in patients with earlier disease onset, suggesting that patients with long GAA repeats and early disease onset have a poor prognosis. Female gender increased the risk of becoming dependent on walking aids or a wheelchair, but it did not influence survival in FRDA, SCA3 and MSA. In SCA2, female gender was associated with shortened survival. In MSA, later age of onset increased the risk of rapid progression and death.

Autosomal dominant cerebellar ataxia type I. Nerve conduction and evoked potential studies in families with SCA1, SCA2 and SCA3

Forty-one patients suffering from autosomal dominant cerebellar ataxia type I (ADCA-I) were subjected to a genotype-phenotype correlation analysis using molecular genetic assignment to the spinocerebellar ataxia type 1, 2 or 3 (SCA1, -2 or -3) genetic locus, clinical examination and nerve conduction as well as evoked potential studies. Pyramidal tract signs, pale discs, and dysphagia were more frequent in SCA1 compared with SCA2 and SCA3 patients, while double vision occurred less frequently. Visual evoked potentials and motor evoked potentials following transcranial magnetic stimulation were abnormal in almost all SCA1 patients, but only in a minority of SCA2 and SCA3 patients. In contrast, somatosensory evoked potentials were delayed or absent in the majority of patients with no significant differences between the mutations. Abnormalities of brainstem auditory evoked potentials were found in about half of the patients irrespective of the underlying mutation. In addition, reduced sensory nerve action potentials, suggesting sensory axonal neuropathy were found in all three mutations. These findings provide electrophysiological evidence that pyramidal and visual pathways are differentially affected in SCA1, SCA2 and SCA3 patients.

Clinical and genetic analysis of three German kindreds with autosomal dominant cerebellar ataxia type I linked to the SCA2 locus

The detailed clinical, electrophysiological and imaging data of three German autosomal dominant cerebellar ataxia (ADCA) families are reported. Linkage to SCA2 was established using microsatellite markers D12S105, D12S1339(1328), D12S1304(1329) yielding a lod score exceeding +3.0 for the combined data. Analysis of the pedigree data provided evidence of anticipation as observed in other neurodegenerative disorders due to polyglutamine expansion encoded by a CAG repeat. This hypothesis was confirmed by the detection of the SCA2-specific pathological protein using the 1C2 monoclonal antibody which selectively recognizes large polyglutamine expansions and the characterization of a CAG expansion in the patients. Clinically, the families were characterized by progressive ataxia of stance, gait and limbs. Saccade velocity was markedly reduced in SCA2. Further oculomotor findings were gaze palsy, impaired smooth pursuit and reduced optokinetic reflex. Dementia and pyramidal tract signs were rather rare, while peripheral involvement (reduced or absent ankle reflexes, fasciculation-like movements, amyotrophy) was a prominent feature. Electrophysiological investigations provided evidence of sensory neuropathy of the axonal type and degeneration of the posterior columns. Imaging studies demonstrated severe shrinkage of brain-stem structures even in early stages of the disease.

Autosomal dominant cerebellar ataxia type I clinical features and MRI in families with SCA1, SCA2 and SCA3

Sixty-five patients suffering from autosomal dominant cerebellar ataxia-I(ADCA-1) were subjected genotype phenotype correlation analysis using molecular genetic assignment to the spinocerebellar ataxia type 1, 2 or 3 (SCA1, -2 or -3) locus, clinical examination, eye movement recording and morphometric analysis of MRIs. Pyramidal tract signs, pale discs and dysphagia were more frequent in SCA1 compared SCA2 and SCA3 patients. Saccade velocity was reduced in 56% of SCA1 and all SCA2, but only in 30% of SCA3 patients. MRIs of SCA2 patients showed atrophy changes typical of severe olivopontocerebellar atrophy (OPCA). The morphological changes in SCA1 were similar but less pronounced. In contrast, SCA3 patients had only mild cerebellar and brain stem atrophy distinct from typical OPCA. The principal finding of this study is that mutations of the SCA2 and SCA3 gene cause phenotypes which can be distinguished in vivo by recording of eye movements and morphometric MRI analysis. Correlative plotting of saccade velocity and diameter of the middle cerebellar peduncle yields a clear separation of SCA2 and SCA3. Spinocerebellar ataxia type I falls into an intermediate range that overlaps with both SCA2 and SCA3. However, the clinical syndrome observed in SCA1 patients is different from that in SCA2 and SCA3.