Abstract Body

The pathogenesis of Parkinson's disease (PD) and Multiple system atrophy (MSA) involves the accumulation of aggregated forms of α-Synuclein in the brain. Progressive staging of α-Synuclein pathology in patient brains correlates with disease symptoms, and disease heterogeneity may be caused by distinct α-Synuclein strains. α-Synuclein pathology can spread in the brain of rodents following intracerebral injection of pathological α-Synuclein seeds. In the current studies, we investigated the ability of recombinant α-Synuclein assemblies with different conformations, i.e. fibrils and ribbons, as well as PD and MSA derived assemblies, i.e. Protein Misfolding Cyclic amplification (PMCA) assemblies and sarkosyl-insoluble fractions, to induce α-Synuclein pathology in primary neurons and mouse brains in vivo.

We showed that recombinant α-Synuclein assemblies induced seeding, with higher potency of fibrils compared to ribbons. PD and MSA PMCA assemblies were potent seeders, although distinct regional and morphological patterns of α-Synuclein pathology were observed in vivo. Sarkosyl-insoluble samples from MSA, but not from PD, were potent seeders in primary neurons.

Ubiquitin colocalization with α-Synuclein aggregates is a robust neuropathological hallmark in patient brains and a better understanding of the regulation of ubiquitinylation may provide important knowledge about the cellular response to α-Synuclein accumulation. We used the primary neuron seeding model to identify specific deubiquitinase enzymes which upon silencing reduced α-Synuclein seeding. These enzymes are under further investigation.

Taken together, our findings support that distinct α-Synuclein strains may define different synucleinopathies and that in vitro and in particular in vivo seeding models might be useful for validating new potential treatment principles.

Abstract Body

Filamentous tau pathology is a hallmark feature of several neurodegenerative diseases, collectively known as tauopathies. Amongst others, P301L and N279K mutations in the gene encoding for tau (MAPT) have been linked to hereditary frontotemporal dementia (FTDP-17T). Recently, several animal and in vitro models have been generated to investigate disease mechanisms in FTDP-17T. However, these models do not fully recapitulate all the aspects of the disease that can be possibly identified in a human system. To investigate the alterations associated with MAPT mutations, we initially set up 2D cultures of induced-pluripotent stem cell (iPSC)-derived neurons from patients with the P301L and N279K mutations, and healthy controls (Iovino et al., 2015). The same IPSCs have now been used to create forebrain and midbrain organoids – brain regions affected in FTDP-17T, to determine whether the 3D models could give better information on the effect of the mutations in different brain regions besides providing a useful human system to investigate tau pathology and spreading. We have been able to generate cerebral organoids with regional identity, which contain both neuronal and glial cells. For both types of organoids, we performed a detailed histological and biochemical characterisation of the tau species and their modifications at different time points. In some organoids, we could observe alterations similar to those seen in tauopathy human brain. In conclusion, these organoids can be used as a tool to investigate mechanisms of tau toxicity and spreading in a human system and for the discovery of novel therapies for neurodegenerative diseases.

Abstract Body

Filamentous tau pathology is a hallmark feature of several neurodegenerative diseases, collectively known as tauopathies. Amongst others, P301L and N279K mutations in the gene encoding for tau (MAPT) have been linked to hereditary frontotemporal dementia (FTDP-17T). Recently, several animal and in vitro models have been generated to investigate disease mechanisms in FTDP-17T. However, these models do not fully recapitulate all the aspects of the disease that can be possibly identified in a human system. To investigate the alterations associated with MAPT mutations, we initially set up 2D cultures of induced-pluripotent stem cell (iPSC)-derived neurons from patients with the P301L and N279K mutations, and healthy controls (Iovino et al., 2015). The same IPSCs have now been used to create forebrain and midbrain organoids – brain regions affected in FTDP-17T, to determine whether the 3D models could give better information on the effect of the mutations in different brain regions besides providing a useful human system to investigate tau pathology and spreading. We have been able to generate cerebral organoids with regional identity, which contain both neuronal and glial cells. For both types of organoids, we performed a detailed histological and biochemical characterisation of the tau species and their modifications at different time points. In some organoids, we could observe alterations similar to those seen in tauopathy human brain. In conclusion, these organoids can be used as a tool to investigate mechanisms of tau toxicity and spreading in a human system and for the discovery of novel therapies for neurodegenerative diseases.