Mutant FUS induces endoplasmic reticulum stress in amyotrophic lateral sclerosis and interacts with protein disulfide-isomerase

Mutations in the gene encoding fused in sarcoma (FUS) are linked to amyotrophic lateral sclerosis (ALS), but the mechanisms by which these mutants trigger neurodegeneration remain unknown. Endoplasmic reticulum (ER) stress is increasingly recognized as an important and early pathway to motor neuron death in ALS. FUS is normally located in the nucleus but in ALS, FUS redistributes to the cytoplasm and forms inclusions. In this study, we investigated whether FUS induces ER stress in a motor neuron like cell line (NSC-34). We demonstrate that ER stress is triggered in cells expressing mutant FUS, and this is closely associated with redistribution of mutant FUS to the cytoplasm. Mutant FUS also colocalized with protein disulfide-isomerase (PDI), an important ER chaperone, in NSC-34 cells and PDI was colocalized with FUS inclusions in human ALS lumbar spinal cords, in both sporadic ALS and mutant FUS-linked familial ALS tissues. These findings implicate ER stress in the pathophysiology of FUS, and provide evidence for common pathogenic pathways in ALS linked to the ER.

Evaluating the role of the FUS/TLS-related gene EWSR1 in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease affecting motor neurons. Mutations in related RNA-binding proteins TDP-43, FUS/TLS and TAF15 have been connected to ALS. These three proteins share several features, including the presence of a bioinformatics-predicted prion domain, aggregation-prone nature in vitro and in vivo and toxic effects when expressed in multiple model systems. Given these commonalities, we hypothesized that a related protein, EWSR1 (Ewing sarcoma breakpoint region 1), might also exhibit similar properties and therefore could contribute to disease. Here, we report an analysis of EWSR1 in multiple functional assays, including mutational screening in ALS patients and controls. We identified three missense variants in EWSR1 in ALS patients, which were absent in a large number of healthy control individuals. We show that disease-specific variants affect EWSR1 localization in motor neurons. We also provide multiple independent lines of in vitro and in vivo evidence that EWSR1 has similar properties as TDP-43, FUS and TAF15, including aggregation-prone behavior in vitro and ability to confer neurodegeneration in Drosophila. Postmortem analysis of sporadic ALS cases also revealed cytoplasmic mislocalization of EWSR1. Together, our studies highlight a potential role for EWSR1 in ALS, provide a collection of functional assays to be used to assess roles of additional RNA-binding proteins in disease and support an emerging concept that a class of aggregation-prone RNA-binding proteins might contribute broadly to ALS and related neurodegenerative diseases.

Sigma nonopioid intracellular receptor 1 mutations cause frontotemporal lobar degeneration-motor neuron disease

OBJECTIVE

Frontotemporal lobar degeneration (FTLD) is the most common cause of early-onset dementia. Pathological ubiquitinated inclusion bodies observed in FTLD and motor neuron disease (MND) comprise trans-activating response element (TAR) DNA binding protein (TDP-43) and/or fused in sarcoma (FUS) protein. Our objective was to identify the causative gene in an FTLD-MND pedigree with no mutations in known dementia genes.

METHODS

A mutation screen of candidate genes, luciferase assays, and quantitative polymerase chain reaction (PCR) was performed to identify the biological role of the putative mutation. Neuropathological characterization of affected individuals and western blot studies of cell lines were performed to identify the pathological mechanism of the mutation.

RESULTS

We identified a nonpolymorphic mutation (c.672*51G>T) in the 3'-untranslated region (UTR) of the Sigma nonopioid intracellular receptor 1 (SIGMAR1) gene in affected individuals from the FTLD-MND pedigree. The c.672*51G>T mutation increased gene expression by 1.4-fold, corresponding with a significant 1.5-fold to 2-fold change in the SIGMAR1 transcript or Sigma-1 protein in lymphocyte or brain tissue. Brains of SIGMAR1 mutation carriers displayed a unique pathology with cytoplasmic inclusions immunopositive for either TDP-43 or FUS but not Sigma-1. Overexpression of SIGMAR1 shunted TDP-43 and FUS from the nucleus to the cytoplasm by 2.3-fold and 5.2-fold, respectively. Treatment of cells with Sigma-1 ligands significantly altered translocation of TDP-43 by up to 2-fold.

INTERPRETATION

SIGMAR1 is a causative gene for familial FTLD-MND with a unique neuropathology that differs from other FTLD and MND cases. Our findings also suggest Sigma-1 drugs as potential treatments for the TDP-43/FUS proteinopathies.

Deposition of Atlantic salmon Salmo salar carcasses in a Scottish upland catchment

Radio telemetry was utilized to track 38 Atlantic salmon Salmo salar across space and time during and following their spawning run on the Conon system, Scotland. The data collected were used to assess the proportion of S. salar able to migrate successfully from an upland oligotrophic area of the catchment and the distribution of the carcasses of those fish that remained. Of these fish, 35% successfully migrated from the study area after the spawning period. The fish that remained were distributed approximately equally between riverine and lacustrine areas, but with a strong tendency to accumulate in regions of relatively slow water flows.

FUS mutations in amyotrophic lateral sclerosis: clinical, pathological, neurophysiological and genetic analysis

OBJECTIVE

FUS gene mutations were recently identified in familial amyotrophic lateral sclerosis (ALS). The present studies sought to define the clinical, post-mortem and neurophysiological phenotypes in ALS families with FUS mutations and to determine the frequency of FUS mutations in familial and sporadic ALS.

METHODS

FUS was screened for mutations in familial and sporadic ALS cases. Clinical, post-mortem and neurophysiological features of large families with FUS mutations are described.

RESULTS AND CONCLUSIONS

FUS mutations were evident in 3.2% (4/124) of familial ALS, representing the second most common gene abnormality to be described in familial ALS after SOD1. No mutations were present in 247 sporadic ALS cases. The clinical presentation in 49 affected patients was consistent with a predominantly lower motor neuron disorder, supported by post-mortem findings. Upper motor neuron involvement varied, with Wallerian degeneration of corticospinal tracts present in one post-mortem case but absent in a second case from the same family. Features of cortical hyperexcitability demonstrated upper motor neuron involvement consistent with other forms of familial and sporadic ALS. One case presented with frontotemporal dementia (FTD) indicating that this may be a rare presenting feature in families with FUS mutation. Ubiquitin-positive cytoplasmic skein-like inclusions were present in lower motor neurons, but in contrast to sporadic ALS, no TDP-43 pathology was evident. Mutation-specific clinical features were identified. Patients with a R521C mutation were significantly more likely to develop disease at a younger age, and dropped-head syndrome was a frequent feature. Reduced disease penetrance was evident among most affected families.

Energy expenditure in the Race Across America (RAAM)

Energy Expenditure was measured with doubly labelled water technique during heavy sustained exercise with an official finishing team in the Race Across America. Energy Intake was also calculated to produce an energy balance for the race. A team of 4 cyclists (Mean +/-SD age: 37+4 yr; body height: 182+8 cm; body mass: 80.8+6.6 kg) completed the race in a relay fashion. The team completed the race in 6 days 10 h and 51 min. Total mean energy expenditure was found to be 43,401 kcals (181,711 kJ) with a mean daily energy expenditure of 6,420 kcals (26,879 kJ). Total mean energy intake from all food and drink consumed was calculated at 29,506 kcals (123,536 kJ) with a mean daily energy intake of 4 918 kcals (20,591 kJ). This resulted in a total mean energy deficit of 13,878 kcals (58,104 kJ) with a mean daily energy deficit of 1,503 kcals (6,293 kJ). The high energy expenditure highlights the need for correct and practical dietary strategies and challenges nutritionists to devise high energy diets that not only contain the correct macronutrient balance, but are also palatable to the cyclists, thus encouraging a high energy intake.

A novel TARDBP mutation in an Australian amyotrophic lateral sclerosis kindred

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder that causes loss of motor neurons. A pathological hallmark of ALS is the presence of ubiquitinated TAR DNA binding protein (TDP-43) inclusions in the cytoplasm of affected cells. Rare pathogenic mutations within the gene TARDBP that encode TDP-43 were recently reported in ALS but their functional consequences are unknown. To further investigate the pathogenic role of TDP-43 in ALS, a mutation analysis of TARDBP was performed in an Australian cohort of 74 sporadic and 30 familial ALS cases. A novel familial ALS mutation in TDP-43 was identified that substitutes a highly conserved residue (G294V) and is predicted to disrupt the glycine rich domain in the C terminus, a region that plays a role in RNA binding and is required for the exon skipping activity of TDP-43.

Mutations in FUS, an RNA processing protein, cause familial amyotrophic lateral sclerosis type 6

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that is familial in 10% of cases. We have identified a missense mutation in the gene encoding fused in sarcoma (FUS) in a British kindred, linked to ALS6. In a survey of 197 familial ALS index cases, we identified two further missense mutations in eight families. Postmortem analysis of three cases with FUS mutations showed FUS-immunoreactive cytoplasmic inclusions and predominantly lower motor neuron degeneration. Cellular expression studies revealed aberrant localization of mutant FUS protein. FUS is involved in the regulation of transcription and RNA splicing and transport, and it has functional homology to another ALS gene, TARDBP, which suggests that a common mechanism may underlie motor neuron degeneration.

TDP-43 mutations in familial and sporadic amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disorder characterized pathologically by ubiquitinated TAR DNA binding protein (TDP-43) inclusions. The function of TDP-43 in the nervous system is uncertain, and a mechanistic role in neurodegeneration remains speculative. We identified neighboring mutations in a highly conserved region of TARDBP in sporadic and familial ALS cases. TARDBPM337V segregated with disease within one kindred and a genome-wide scan confirmed that linkage was restricted to chromosome 1p36, which contains the TARDBP locus. Mutant forms of TDP-43 fragmented in vitro more readily than wild type and, in vivo, caused neural apoptosis and developmental delay in the chick embryo. Our evidence suggests a pathophysiological link between TDP-43 and ALS.

Arts syndrome is caused by loss-of-function mutations in PRPS1

Arts syndrome is an X-linked disorder characterized by mental retardation, early-onset hypotonia, ataxia, delayed motor development, hearing impairment, and optic atrophy. Linkage analysis in a Dutch family and an Australian family suggested that the candidate gene maps to Xq22.1-q24. Oligonucleotide microarray expression profiling of fibroblasts from two probands of the Dutch family revealed reduced expression levels of the phosphoribosyl pyrophosphate synthetase 1 gene (PRPS1). Subsequent sequencing of PRPS1 led to the identification of two different missense mutations, c.455T-->C (p.L152P) in the Dutch family and c.398A-->C (p.Q133P) in the Australian family. Both mutations result in a loss of phosphoribosyl pyrophosphate synthetase 1 activity, as was shown in silico by molecular modeling and was shown in vitro by phosphoribosyl pyrophosphate synthetase activity assays in erythrocytes and fibroblasts from patients. This is in contrast to the gain-of-function mutations in PRPS1 that were identified previously in PRPS-related gout. The loss-of-function mutations of PRPS1 likely result in impaired purine biosynthesis, which is supported by the undetectable hypoxanthine in urine and the reduced uric acid levels in serum from patients. To replenish low levels of purines, treatment with S-adenosylmethionine theoretically could have therapeutic efficacy, and a clinical trial involving the two affected Australian brothers is currently underway.

Identification of novel genes and transcription factors involved in spleen, thymus and immunological development and function

We constructed and analyzed six serial analysis of gene expression (SAGE) libraries to identify genes with previously uncharacterized roles in spleen or thymus development. A total of 625 070 tags were sequenced from the three spleen (embryonic day (E)15.5, E16.5 and adult) and three thymus (E15.5, E18.5 and adult) libraries. These tags corresponded to 83 182 tag types, which mapped unambiguously to 36 133 different genes. Genes over-represented in these libraries, compared to 115 mouse SAGE libraries (www.mouseatlas.org), included genes of known and unknown immunological or developmental relevance. The expression profiles of 11 genes with unknown roles in spleen and thymus development were validated using reverse transcription-qPCR. We further characterized the expression of one of these candidates, RIKEN cDNA 9230105E10 that encodes a murine homolog of Trim5alpha, in numerous adult tissues and immune cell types. In addition, we demonstrate that transcript levels are upregulated in response to TLR stimulation of plasmacytoid dendritic cells and macrophages. This work provides the first evidence of regulated and cell type-specific expression of this gene. In addition, these observations suggest that the SAGE libraries provide an important resource for further investigations into the molecular mechanisms regulating spleen and thymus organogenesis, as well as the development of immunological competence.

Effects on respiratory health of a reduction in air pollution from vehicle exhaust emissions

AIMS

To determine whether residents of congested streets have a higher prevalence of respiratory symptoms than residents of nearby uncongested streets, and whether their respiratory health improves following a reduction in exposure to traffic related air pollutants.

METHODS

An area was identified where certain streets were subject to air pollution from heavy road traffic, which was likely to improve following the construction of a by-pass. A respiratory survey was conducted among the residents, together with the residents of nearby uncongested streets, at baseline and again a year after the by-pass opened. Measurements were made of air pollutant concentrations in both areas on both occasions.

RESULTS

Initial concentrations of PM10 and PM2.5 were substantially higher in the congested than in the uncongested streets. When the by-pass opened, the volume of heavy goods traffic fell by nearly 50%. PM10 decreased by 23% (8.0 microg/m3) in the congested streets and by 29% (3.4 microg/m3) in the uncongested streets, with similar proportionate falls in PM2.5. There were no clear or consistent differences between the residents of the two areas initially in terms of symptoms or peak flow variability. Repeat questionnaires were obtained from 165 and 283 subjects in the congested and uncongested areas respectively, and showed a tendency for most symptoms to improve in both areas. For chest symptoms, the improvement tended to be greater in the uncongested area, although the difference between the areas was not statistically significant. Rhinitis and rhinoconjunctivitis tended to improve to a greater extent in the congested streets; the difference between the areas was significant for the degree to which rhinitis interfered with daily activities. Peak flow variability tended to improve in the uncongested area.

CONCLUSIONS

The by-pass reduced pollutant levels to a degree that probably alleviates rhinitis and rhinoconjunctivitis but has little effect on lower respiratory symptoms.

Phylogeography of the coronulid barnacle, Chelonibia testudinaria, from loggerhead sea turtles, Caretta caretta

The barnacle, Chelonibia testudinaria, is a common inhabitant of the marine turtle epibiont community and plays a key role in the development of this community. Phylogeographic analysis of 79 cytochrome c oxidase I (COX1) sequences for barnacles collected from five populations found contrasting patterns of divergence for populations in the Atlantic vs. the Pacific Ocean. Our analysis indicates that the two Pacific populations, Senri Beach, Japan and Bahia Magdalena, Mexico, were not only highly divergent from the Atlantic populations but are highly divergent from one another. We suggest that barnacles from these populations may represent cryptic species. In contrast, sequence divergence was greatly reduced among barnacles collected from Wassaw Island, GA, USA, Keewaydin, FL, USA, and Kyparissia, Pèloponnésus Island, Greece. A reduction in sequence diversity at the latter site was attributed to a recent range expansion into the Mediterranean Sea. We examined historical patterns of migration among the three Atlantic and Mediterranean populations using the program migrate. This analysis indicates a high rate of migration from Keewaydin to Wassaw Island, contrasted with a much lower rate of migration in the opposite direction. The estimated migration rate from Kyparissia to Keewaydin was also non-negligible. We suggest that the association between C. testudinaria and loggerhead turtles and the patterns of turtle migration have played key roles in the expansion of the range of C. testudinaria into the Mediterranean Sea and the subsequent patterns of barnacle migration. We further propose that the difference between ocean basins, with respect to the impact of host migration on barnacle gene flow, probably stems from the fact that host-mediated dispersal in the Atlantic depends on advanced stage juveniles and adults while any host-mediated dispersal in the Pacific would have to involve early "pelagic" stage juvenile loggerheads.

Effect of opioid receptor antagonists on hypothalamic-pituitary-adrenal activity in rhesus monkeys

Some opioid antagonists increase the release of adrenocorticotropic hormone (ACTH) and cortisol in humans and, therefore, may indicate that endogenous opioids modulate hypothalamic-pituitary-adrenal axis activity. The type of opioid receptor that may be related to these endocrine effects is unknown. The purpose of this experiment was to evaluate the ability of different opioid antagonists to increase ACTH and cortisol plasma levels in rhesus monkeys. Eight monkeys received intramuscular injections of various antagonists: 0.0032-1.0 mg/kg naltrexone, 0.1-3.2 mg/kg naltrindole (delta-selective), 0.032-0.32 mg/kg clocinnamox (mu-selective), and 1-3.2 mg/kg nor-binaltorphimine (kappa-selective). Naltrexone, 0.1-1.0 mg/kg, increased ACTH levels, whereas naltrindole and clocinnamox failed to increase ACTH levels. Nor-binaltorphimine, 1-3.2 mg/kg, increased ACTH concentrations on the day of injection, but not at a time when other assays continue to demonstrate kappa-antagonism (24 h). Cortisol concentrations generally followed the same pattern as the ACTH concentrations, but the incremental differences in cortisol release between doses were less clear. Thus, opioid modulation of ACTH and cortisol plasma levels is not clearly associated with a particular opioid receptor. Although the kappa-antagonist increased ACTH and cortisol release on the day of injection, some evidence suggests that this endocrine effect may be due to mechanisms other than those mediated by the kappa-receptor. Alternatively, the naltrexone-induced increase of ACTH and cortisol plasma levels may be caused by activity at multiple opioid receptors or some uncharacterized receptor. Finally, the increased release of ACTH and cortisol may be a response to naltrexone's aversive properties.

Ultrastructure and properties of Paecilomyces lilacinus spores

Strains of the filamentous soil fungus Paecilomyces lilacinus are currently being developed for use as biological control agents against root-knot, cyst, and other plant-parasitic nematodes. The inoculum applied in the field consists mainly of spores. This study was undertaken to examine the size, ultrastructure, and rodlet layers of P. lilacinus spores and the effect of the culture method on structural and functional spore properties. A rodlet layer was identified on aerial spores only. Other differences noted between aerial spores and those produced in submerged culture included the size and appearance of spores and thickness of spore coat layers when examined with transmission electron microscopy. The two spore types differed in UV tolerance, with aerial spores being less sensitive to environmentally relevant UV radiation. Also, viability after drying and storage was better with the aerial spores. Both spore types exhibited similar nematophagous ability.

Bias in risk estimation: application to Down's syndrome screening

In this paper we consider the bias associated with parametric estimation of a univariate or bivariate Gaussian density, and also the induced bias when these Gaussian densities are used to determine a likelihood ratio. Algebraic approximations are derived that accurately predict the relative biases obtained, verification being achieved by a simulation exercise. The expressions confirm that when estimating a univariate Gaussian density there are four Z-scores for which there is zero bias and that relative bias increases rapidly beyond two standard deviations from the mean. The results are then extended to determine approximate confidence intervals for both the true density and the likelihood ratio. A simulation exercise confirms that the derived 95 per cent confidence intervals have coverage that ranges from 94 to 97 per cent. The results are applied to a Down's syndrome screening programme where 95 per cent confidence intervals are established for a woman's posterior odds of carrying a Down's foetus. It is shown that patients with similar posterior odds can give rise to confidence intervals for their true posterior odds that have very different widths, thus emphasizing that not all risks are of equal quality.

Prevention of venous thromboembolism in Wales: results of a survey among general surgeons

OBJECTIVE

To examine the current attitudes towards the prevention of venous thromboembolism among a cohort of surgeons.

DESIGN

A postal survey, comprising a questionnaire covering various aspects of venous thromboembolism prophylaxis was sent to all (n=84) consultant general surgeons in Wales.

RESULTS

Replies were received from 57 surgeons (68%), all of whom routinely used prophylaxis, the most frequent modalities used being heparin (100%) and graded compression stockings (79%). A combination of physical and pharmacological methods was used by over 89% of surgeons, with 60% starting prophylaxis more than two hours before operation. All surgeons continued prophylaxis after surgery, 53% until patients were mobile, 45% until they were discharged, and one surgeon continued prophylaxis for seven days after discharge. The thrombosis risk factors considered most important by surgeons when deciding about prophylaxis were (i) a previous history of venous thromboembolism, (ii) hypercoagulability, and (iii) malignancy.

CONCLUSIONS

This study confirms that Welsh surgeons conform to standard methods, but also highlights some uncertainties that are present in current surgical practice. Those who responded all routinely used prophylaxis, the timing of which was variable. The main risk factors identified when considering prophylaxis were previous history of deep vein thrombosis/pulmonary embolism, hypercoagulability, and the presence of malignancy. Suggestions for future practice are made.

Factors associated with asthma in Albania

BACKGROUND

This study was undertaken to see whether asthma in Albania (where it is particularly uncommon) is associated with certain 'western' characteristics, and with dietary and lifestyle factors that affect its occurrence elsewhere.

METHODS

A screening survey was conducted among 2653 persons aged 20-44 years. A more detailed enquiry was conducted among a random subsample plus all others whose response indicated possible asthma. Three groups were compared: 495 probable nonasthmatics ('nonsymptomatics'); 106 with asthma-like symptoms and positive skin tests ('possible allergic asthmatics'); and 116 with similar symptoms and negative skin tests ('other symptomatics').

RESULTS

The possible allergic asthmatics were less likely than the nonsymptomatics to have attended school or nursery under the age of 5 years or to have shared a bedroom with an older child before that age. Continued education after the age of 18 years also appeared to be protective. Allowing for other factors, a strong negative relation was found with fruit and vegetable consumption, and weak positive relations with prepackaged food and fizzy drinks. Symptoms in skin prick test-negative subjects were associated with personal and parental smoking habit.

CONCLUSIONS

This survey provides limited evidence linking asthma with aspects of western lifestyle. It supports the hypothesis that opportunities for infection during early childhood and the consumption of fruit and vegetables protect against asthma.

An effective density fluid model for acoustic propagation in sediments derived from Biot theory

In this paper we present an acoustic propagation model that approximates a porous medium as a fluid with a bulk modulus and effective density derived from Biot theory. Within the framework of Biot theory it is assumed here that the porous medium has low values of frame bulk and shear moduli relative to the other moduli of the medium and these low values are approximated as zero. This leads to an effective density fluid model. It is shown that, for saturated sand sediments, the dispersion, transmission, reflection, and in-water backscattering predicted with this effective density fluid model are in close agreement with the predictions of Biot theory. In this agreement we demonstrate that the frame bulk and shear moduli play only a minor role in determining several aspects of sand acoustics. Thus, for many applications the effective density fluid model is an accurate alternative to full Biot theory and is much simpler to implement.

What place for polyacrylamide in proteomics?

Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) continues to deliver high quality protein resolution and dynamic range for the proteomics researcher. To remain as the preferred method for protein separation and characterization, several key steps need to be implemented to ensure quality sample preparation and speed of analysis. Here, we describe the progress made towards establishing 2D-PAGE as the optimal separation tool for proteomics research.