α-Synuclein promotes IAPP fibril formation in vitro and β-cell amyloid formation in vivo in mice.

Mucibabic M, Steneberg P, Lidh E, Straseviciene J, Ziolkowska A, Dahl U, Lindahl E, Edlund H

Sci Rep 10 (1) 20438 [2020-11-24; online 2020-11-24]

Type 2 diabetes (T2D), alike Parkinson's disease (PD), belongs to the group of protein misfolding diseases (PMDs), which share aggregation of misfolded proteins as a hallmark. Although the major aggregating peptide in β-cells of T2D patients is Islet Amyloid Polypeptide (IAPP), alpha-synuclein (αSyn), the aggregating peptide in substantia nigra neurons of PD patients, is expressed also in β-cells. Here we show that αSyn, encoded by Snca, is a component of amyloid extracted from pancreas of transgenic mice overexpressing human IAPP (denoted hIAPPtg mice) and from islets of T2D individuals. Notably, αSyn dose-dependently promoted IAPP fibril formation in vitro and tail-vein injection of αSyn in hIAPPtg mice enhanced β-cell amyloid formation in vivo whereas β-cell amyloid formation was reduced in hIAPPtg mice on a Snca -/- background. Taken together, our findings provide evidence that αSyn and IAPP co-aggregate both in vitro and in vivo, suggesting a role for αSyn in β-cell amyloid formation.

Cryo-EM [Service]

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PubMed 33235246

DOI 10.1038/s41598-020-77409-z

Crossref 10.1038/s41598-020-77409-z

pii: 10.1038/s41598-020-77409-z
pmc: PMC7686322