RT Journal Article SR Electronic T1 C9ORF72-derived poly-GA DPRs undergo endocytic uptake in iAstrocytes and spread to motor neurons JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202101276 DO 10.26508/lsa.202101276 VO 5 IS 9 A1 Marchi, Paolo M A1 Marrone, Lara A1 Brasseur, Laurent A1 Coens, Audrey A1 Webster, Christopher P A1 Bousset, Luc A1 Destro, Marco A1 Smith, Emma F A1 Walther, Christa G A1 Alfred, Victor A1 Marroccella, Raffaele A1 Graves, Emily J A1 Robinson, Darren A1 Shaw, Allan C A1 Wan, Lai Mei A1 Grierson, Andrew J A1 Ebbens, Stephen J A1 De Vos, Kurt J A1 Hautbergue, Guillaume M A1 Ferraiuolo, Laura A1 Melki, Ronald A1 Azzouz, Mimoun YR 2022 UL https://www.life-science-alliance.org/content/5/9/e202101276.abstract AB Dipeptide repeat (DPR) proteins are aggregation-prone polypeptides encoded by the pathogenic GGGGCC repeat expansion in the C9ORF72 gene, the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. In this study, we focus on the role of poly-GA DPRs in disease spread. We demonstrate that recombinant poly-GA oligomers can directly convert into solid-like aggregates and form characteristic β-sheet fibrils in vitro. To dissect the process of cell-to-cell DPR transmission, we closely follow the fate of poly-GA DPRs in either their oligomeric or fibrillized form after administration in the cell culture medium. We observe that poly-GA DPRs are taken up via dynamin-dependent and -independent endocytosis, eventually converging at the lysosomal compartment and leading to axonal swellings in neurons. We then use a co-culture system to demonstrate astrocyte-to-motor neuron DPR propagation, showing that astrocytes may internalise and release aberrant peptides in disease pathogenesis. Overall, our results shed light on the mechanisms of poly-GA cellular uptake and propagation, suggesting lysosomal impairment as a possible feature underlying the cellular pathogenicity of these DPR species.