ALS-Associated Endoplasmic Reticulum Proteins in Denervated Skeletal Muscle: Implications for Motor Neuron Disease Pathology.

Alpha-motoneurons and muscle fibres are structurally and functionally interdependent. Both cell types particularly rely on endoplasmic reticulum (ER/SR) functions. Mutations of the ER proteins VAPB, SigR1 and HSP27 lead to hereditary motor neuron diseases (MNDs). Here, we determined the expression profile and localization of these ER proteins/chaperons by immunohistochemistry and immunoblotting in biopsy and autopsy muscle tissue of patients with amyotrophic lateral sclerosis (ALS) and other neurogenic muscular atrophies (NMAs) and compared these patterns to mouse models of neurogenic muscular atrophy. Postsynaptic neuromuscular junction staining for VAPB was intense in normal human and mouse muscle and decreased in denervated Nmd2J mouse muscle fibres. In contrast, VAPB levels together with other chaperones and autophagy markers were increased in extrasynaptic regions of denervated muscle fibres of patients with MNDs and other NMAs, especially at sites of focal myofibrillar disintegration (targets). These findings did not differ between NMAs due to ALS and other causes. G93A-SOD1 mouse muscle fibres showed a similar pattern of protein level increases in denervated muscle fibres. In addition, they showed globular VAPB-immunoreactive structures together with misfolded SOD1 protein accumulations, suggesting a primary myopathic change. Our findings indicate that altered expression and localization of these ER proteins and autophagy markers are part of the dynamic response of muscle fibres to denervation. The ER is particularly prominent and vulnerable in both muscle fibres and alpha-motoneurons. Thus, ER pathology could contribute to the selective build-up of degenerative changes in the neuromuscular axis in MNDs.

Loss of function of the ALS protein SigR1 leads to ER pathology associated with defective autophagy and lipid raft disturbances.

Intracellular accumulations of altered, misfolded proteins in neuronal and other cells are pathological hallmarks shared by many neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Mutations in several genes give rise to familial forms of ALS. Mutations in Sigma receptor 1 have been found to cause a juvenile form of ALS and frontotemporal lobar degeneration (FTLD). We recently described altered localization, abnormal modification and loss of function of SigR1 in sporadic ALS. In order to further elucidate the molecular mechanisms underlying SigR1-mediated alterations in sporadic and familial ALS, we extended our previous studies using neuronal SigR1 knockdown cell lines. We found that loss of SigR1 leads to abnormal ER morphology, mitochondrial abnormalities and impaired autophagic degradation. Consistent with these results, we found that endosomal trafficking of EGFR is impaired upon SigR1 knockdown. Furthermore, in SigR1-deficient cells the transport of vesicular stomatitis virus glycoprotein is inhibited, leading to the accumulation of this cargo protein in the Golgi apparatus. Moreover, depletion of SigR1 destabilized lipid rafts and associated calcium mobilization, confirming the crucial role of SigR1 in lipid raft and intracellular calcium homeostasis. Taken together, our results support the notion that loss of SigR1 function contributes to ALS pathology by causing abnormal ER morphology, lipid raft destabilization and defective endolysosomal pathways.

Analysing policy interventions to prohibit over-the-counter antibiotic sales in four Latin American countries.

OBJECTIVES: To describe and evaluate policies implemented in Chile, Colombia, Venezuela and Mexico (1995-2009) to prohibit antibiotic OTC sales and explore limitations in available data. METHODS: We searched and analysed legislation, grey literature and peer-reviewed publications on regulatory interventions and implementation strategies to enforce prohibition of OTC antibiotic sales. We also assessed the impact using private sector retail sales data of antibiotics studying changes in level and consumption trends before and after the policy change using segmented time series analysis. Finally, we assessed the completeness and data quality through an established checklist to test the suitability of the data for analysis of the interventions. RESULTS: Whereas Chile implemented a comprehensive package of interventions to accompany regulation changes, Colombia's reform was limited to the capital district and Venezuela's limited to only some antibiotics and without awareness campaigns. In Mexico, no enforcement was enacted. The data showed a differential effect of the intervention among the countries studied with a significant change in level of consumption in Chile (-5.56 DID) and in Colombia (-1.00DID). In Venezuela and Mexico, no significant change in level and slope was found. Changes in population coverage were identified as principal limitations of using sales data for evaluating the reform impact. CONCLUSION: Retail sales data can be useful when assessing policy impact but should be supplemented by other data sources such as public sector sales and prescription data. Implementing regulatory enforcement has shown some impact, but a sustainable, concerted approach will be needed to address OTC sales in the future.