2021
DOI:10.1038/s41467-021-23188-8
PMID: 34021139
PMCID: PMC8140117
Synaptic accumulation of FUS triggers age-dependent misregulation of inhibitory synapses in ALS-FUS mice
Sonu Sahadevan*, Katharina M. Hembach*, Elena Tantardini, Marian Hruska-Plochan, Manuela Pérez-Berlanga, Julien Weber, Petra Schwarz, Luc Dupuis, Mark D. Robinson, Pierre De Rossi, Magdalini Polymenidou
Abstract: FUS is a primarily nuclear RNA-binding protein with important roles in RNA processing and transport. FUS mutations disrupting its nuclear localization characterize a subset of amyotrophic lateral sclerosis (ALS-FUS) patients, through an unidentified pathological mechanism. FUS regulates nuclear RNAs, but its role at the synapse is poorly understood. Here, we used super-resolution imaging to determine the physiological localization of extranuclear, neuronal FUS and found it predominantly near the vesicle reserve pool of presynaptic sites. Using CLIP-seq on synaptoneurosome preparations, we identified synaptic RNA targets of FUS that are associated with synapse organization and plasticity. Synaptic FUS was significantly increased in a knock-in mouse model of ALS-FUS, at presymptomatic stages. Despite apparently unaltered synaptic organization, RNA-seq of synaptoneurosomes highlighted age-dependent dysregulation of glutamatergic and GABAergic synapses. Our study indicates that FUS relocalization to the synapse in early stages of ALS-FUS results in synaptic impairment, potentially representing an initial trigger of neurodegeneration.
DOI:10.1038/s41467-021-23187-9
PMID: 34021132
Cytoplasmic accumulation of FUS triggers early behavioral alterations linked to cortical neuronal hyperactivity and defects in inhibitory synapses
Jelena Scekic-Zahirovic*, Inmaculada Sanjuan-Ruiz*, Vanessa Kan, Salim Megat, Pierre de Rossi, Stéphane Dieterlé, Raphaelle Cassel, Pascal Kessler, Diana Wiesner, Laura Tzeplaeff, Valérie Demais, Gina Picchiarelli, Nibha Mishra, Sylvie Grosch, Jan Kassubek, Albert Ludolph, Anne-Laurence Boutillier, Magdalini Polymenidou, Clotilde Lagier-Tourenne, Sabine Liebscher#, Luc Dupuis#
Abstract: Mutations in fused in sarcoma (FUS), a RNA binding protein involved in multiple/various steps of RNA metabolism, lead to cytoplasmic mislocalization of FUS and are characteristic of a subset of amyotrophic lateral sclerosis cases (ALS-FUS), with early onset and rapid progression. Cytoplasmic FUS mislocalization is also observed in sporadic ALS, as well as in other neurodegenerative diseases such as fronto-temporal dementia (FTD). There are however few information on consequences of FUS mislocalization beyond motor neurons. Here, we show that a partial cytoplasmic mislocalization of FUS in heterozygous Fus knock-in mice is sufficient to drive a panel of behavioral abnormalities, including locomotor hyperactivity or alterations in social interactions, at early timepoints preceding motor neuron degeneration. This was accompanied by ventricle enlargement in the absence of widespread neuronal cell loss. Mechanistically, we could identify a strong increase of neuronal activity in the frontal cortex of Fus knock-in mice in vivo. Furthermore, we observed impaired expression of multiple genes related to neuronal function in the frontal cortex throughout adulthood. Genes differentially regulated were selectively related to inhibitory neurons and we observed ultrastructural and morphological defects of inhibitory synapses accompanied by increased levels of Fus, Nrxn1 and Gabra1 mRNAs in synaptosomes of heterozygous Fus knock-in mice. Thus, FUS cytoplasmic enrichment is sufficient to trigger inhibitory synaptic deficits leading to increased neuronal activity and behavioral phenotypes. These findings suggest that FUS mislocalization could trigger deleterious phenotypes beyond motor neurons that could be relevant for both ALS-FUS but also other neurodegenerative diseases with FUS mislocalization.
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DOI:10.15252/emmm.202114745
PMID: 34309222
LAG3 is not expressed in human and murine neurons and does not modulate α-synucleinopathies
Marc Emmenegger, Elena De Cecco, Marian Hruska-Plochan, Timo Eninger, Matthias M Schneider, Melanie Barth, Elena Tantardini, Pierre de Rossi, Mehtap Bacioglu, Rebekah G Langston, Alice Kaganovich, Nora Bengoa-Vergniory, Andrès Gonzalez-Guerra, Merve Avar, Daniel Heinzer, Regina Reimann, Lisa M Häsler, Therese W Herling, Naunehal S Matharu, Natalie Landeck, Kelvin Luk, Ronald Melki, Philipp J Kahle, Simone Hornemann, Tuomas P J Knowles, Mark R Cookson, Magdalini Polymenidou, Mathias Jucker, Adriano Aguzzi
Abstract: While the initial pathology of Parkinson’s disease and other α-synucleinopathies is often confined to circumscribed brain regions, it can spread and progressively affect adjacent and distant brain locales. This process may be controlled by cellular receptors of α-synuclein fibrils, one of which was proposed to be the LAG3 immune checkpoint molecule. Here, we analysed the expression pattern of LAG3 in human and mouse brains. Using a variety of methods and model systems, we found no evidence for LAG3 expression by neurons. While we confirmed that LAG3 interacts with α-synuclein fibrils, the specificity of this interaction appears limited. Moreover, overexpression of LAG3 in cultured human neural cells did not cause any worsening of α-synuclein pathology ex vivo. The overall survival of A53T α-synuclein transgenic mice was unaffected by LAG3 depletion, and the seeded induction of α-synuclein lesions in hippocampal slice cultures was unaffected by LAG3 knockout. These data suggest that the proposed role of LAG3 in the spreading of α-synucleinopathies is not universally valid.
DOI:10.15252/embr.202153877
PMID: 34806807
FTLD-TDP assemblies seed neoaggregates with subtype-specific features via a prion-like cascade
Pierre De Rossi*, Amanda J Lewis*, Johanna Furrer, Laura De Vos, Tomas Demeter, Aurélie Zbinden, Weijia Zhong, Vera I Wiersma, Carlo Scialo, Julien Weber, Zhongning Guo, Stefano Scaramuzza, Marta Di Fabrizio, Carolin Böing, Daniel Castaño-Díez, Ashraf Al-Amoudi, Manuela Pérez-Berlanga, Tammaryn Lashley, Henning Stahlberg, Magdalini Polymenidou
Abstract: Morphologically distinct TDP-43 aggregates occur in clinically different FTLD-TDP subtypes, yet the mechanism of their emergence and contribution to clinical heterogeneity are poorly understood. Several lines of evidence suggest that pathological TDP-43 follows a prion-like cascade, but the molecular determinants of this process remain unknown. We use advanced microscopy techniques to compare the seeding properties of pathological FTLD-TDP-A and FTLD-TDP-C aggregates. Upon inoculation of patient-derived aggregates in cells, FTLD-TDP-A seeds amplify in a template-dependent fashion, triggering neoaggregation more efficiently than those extracted from FTLD-TDP-C patients, correlating with the respective disease progression rates. Neoaggregates are sequentially phosphorylated with N-to-C directionality and with subtype-specific timelines. The resulting FTLD-TDP-A neoaggregates are large and contain densely packed fibrils, reminiscent of the pure compacted fibrils present within cytoplasmic inclusions in postmortem brains. In contrast, FTLD-TDP-C dystrophic neurites show less dense fibrils mixed with cellular components, and their respective neoaggregates are small, amorphous protein accumulations. These cellular seeding models replicate aspects of the patient pathological diversity and will be a useful tool in the quest for subtype-specific therapeutics.