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Exposure to heavy metals, including arsenic and cadmium, is associated with neurodegenerative disorders such as Parkinson's disease. However, the mechanistic details of how these metals contribute to pathogenesis are not well understood. To search for underlying mechanisms involving α-synuclein, the protein that forms amyloids in Parkinson's disease, we here assessed the effects of arsenic and cadmium on α-synuclein amyloid formation in vitro and in Saccharomyces cerevisiae (budding yeast) cells. Atomic force microscopy experiments with acetylated human α-synuclein demonstrated that amyloid fibers formed in the presence of the metals have a different fiber pitch compared to those formed without metals. Both metal ions become incorporated into the amyloid fibers, and cadmium also accelerated the nucleation step in the amyloid formation process, likely via binding to intermediate species. Fluorescence microscopy analyses of yeast cells expressing fluorescently tagged α-synuclein demonstrated that arsenic and cadmium affected the distribution of α-synuclein aggregates within the cells, reduced aggregate clearance, and aggravated α-synuclein toxicity. Taken together, our in vitro data demonstrate that interactions between these two metals and α-synuclein modulate the resulting amyloid fiber structures, which, in turn, might relate to the observed effects in the yeast cells. Whilst our study advances our understanding of how these metals affect α-synuclein biophysics, further in vitro characterization as well as human cell studies are desired to fully appreciate their role in the progression of Parkinson's disease.

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The toxic metalloid arsenic causes widespread misfolding and aggregation of cellular proteins. How these protein aggregates are formed in vivo, the mechanisms by which they affect cells and how cells prevent their accumulation is not fully understood. To find components involved in these processes, we performed a genome-wide imaging screen and identified Saccharomyces cerevisiae deletion mutants with either enhanced or reduced protein aggregation levels during arsenite exposure. We show that many of the identified factors are crucial to safeguard protein homeostasis (proteostasis) and to protect cells against arsenite toxicity. The hits were enriched for various functions including protein biosynthesis and transcription, and dedicated follow-up experiments highlight the importance of accurate transcriptional and translational control for mitigating protein aggregation and toxicity during arsenite stress. Some of the hits are associated with pathological conditions, suggesting that arsenite-induced protein aggregation may affect disease processes. The broad network of cellular systems that impinge on proteostasis during arsenic stress identified in this current study provides a valuable resource and a framework for further elucidation of the mechanistic details of metalloid toxicity and pathogenesis. This article has an associated First Person interview with the first authors of the paper.

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Resumo A hospitalização pediátrica é um acontecimento crítico, com repercussões na vida da criança internada e da sua família. Este estudo teve como objetivos auscultar as principais preocupações e necessidades experienciadas pelos pais durante a hospitalização de um filho em situação de internamento agudo e explorar eventuais diferenças entre o pai e a mãe no conjunto de vivências partilhadas. Para isso, realizou-se um estudo qualitativo, de natureza exploratória, do qual participaram 16 casais (16 pais e 16 mães) com um filho internado no serviço de pediatria de um hospital do norte de Portugal. Os dados foram recolhidos por meio de entrevistas e avaliados com base na metodologia de análise de conteúdo. O discurso dos pais evidencia como preocupações mais expressivas as referentes ao estado de saúde do filho e, entre as necessidades mais prementes, as associadas à sua recuperação e regresso ao domicílio. Os resultados encontrados revelam igualmente a presença de expressivas diferenças nas vivências desses casais, não devidas à variável pai/mãe, mas à centralidade do papel assumido em termos dos cuidados ao filho (cuidador principal ou secundário).

Abstract Pediatric hospitalization is a critical event with repercussions on the life of hospitalized children and their families. This study recorded the main concerns and needs experienced by parents during the hospitalization of a child under acute hospitalization, and verified the potential differences between the father and the mother regarding their shared experiences. This qualitative study of exploratory nature involved 16 couples (16 fathers and 16 mothers), with a child hospitalized in a pediatric service of a hospital in the north of Portugal. The data were collected through interviews and analyzed using content analysis. The parents' discourse shows significantly more concern regarding the state of health of the child as well as their recovery and homecoming, among the most urgent needs. The results showed presence of significant differences in the experiences of these couples, not only due to the father/mother variable, but also due to their central role regarding child care (primary or secondary caregiver).

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