The role of inclusions in ALS pathogenesis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that primarily afflicts motor neurons, leading to paralysis and death within 3 to 5 years after diagnosis. Genetic studies have uncovered multiple genetic defects causing familial forms of ALS and mutations occurring in proteins with a variety of functions, including RNA metabolism (TDP43, FUS) and oxygen free radical homeostasis (SOD1). A commonality among all ALS forms is the presence of intracellular inclusions that primarily consist of insoluble protein aggregates. These inclusions indicate that protein aggregation is a central pathogenic event shared by multiple ALS forms. The research of the present thesis focuses on the role of protein aggregation and inclusion formation in two types of ALS: 1) ALS caused by mutations in the superoxide dismutase 1 (SOD1) gene (ALS1); and 2) ALS caused by mutations in the vesicle-associated membrane protein (VAMP)-associated protein B (VAPB) gene (ALS8)

Amyotrophic lateral sclerosis (ALS)-associated VAPB-P56S inclusions represent an ER quality control compartment

BACKGROUND: Protein aggregation and the formation of intracellular inclusions are a central feature of many neurodegenerative disorders, but precise knowledge about their pathogenic role is lacking in most instances. Here we have characterized inclusions formed in transgenic mice carrying the P56S mutant form of VAPB that causes various motor neuron syndromes including ALS8.RESULTS: Inclusions in motor neurons of VAPB-P56S transgenic mice are characterized by the presence of smooth ER-like tubular profiles, and are immunoreactive for factors that operate in the ER associated degradation (ERAD) pathway, including p97/VCP, Derlin-1, and the ER membrane chaperone BAP31. The presence of these inclusions does not correlate with signs of axonal and neuronal degeneration, and axotomy leads to their gradual disappearance, indicating that they represent reversible structures. Inhibition of the proteasome and knockdown of the ER membrane chaperone BAP31 increased the size of mutant VAPB inclusions in primary neuron cultures, while knockdown of TEB4, an ERAD ubiquitin-protein ligase, reduced their size. Mutant VAPB did not codistribute with mutant forms of seipin that are associated with an autosomal dominant motor neuron disease, and accumulate in a protective ER derived compartment termed ERPO (ER protective organelle) in neurons.CONCLUSIONS: The data indicate that the VAPB-P56S inclusions represent a novel reversible ER quality control compartment that is formed when the amount of mutant VAPB exceeds the capacity of the ERAD pathway and that isolates misfolded and aggregated VAPB from the rest of the ER. The presence of this quality control compartment reveals an additional level of flexibility of neurons to cope with misfolded protein stress in the ER

Xanthoma in the external acoustic meatus

Objectivesa unique case of a xanthoma in the external ear canal of a pediatric patient is presented in this case report. We describe and resume the current literature on xanthomas in the head and neck area.Methodsclinical and intraoperative findings are reported and the presumed mechanisms for the emergence of xanthomas are discussed. We furthermore described the pathologic and immunohistochemical characteristics.Resultsxanthomas are mostly seen in patients with lipid metabolism disorders or hyperlipidemia. However, they can be present in normolipemic patients and are also associated with hematologic disease. Literature on the existence of xanthomata in the head and neck area is rare and there are no case reports in the pediatric population to the best of our knowledge. Besides the clinical presentation, characteristic histopathological features can confirm the diagnosis. When features are overlapping, immunohistochemistry can be necessary.Conclusionsince different subtypes of xanthoma have specific clinical and histopathological features and are assoc