Munc18-1 is a molecular chaperone for α-synuclein, controlling its self-replicating aggregation.
Munc18-1 is a key component of the exocytic machinery that controls neurotransmitter release. Munc18-1 heterozygous mutations cause developmental defects and epileptic phenotypes, including infantile epileptic encephalopathy (EIEE), suggestive of a gain of pathological function. Here, we used single-molecule analysis, gene-edited cells, and neurons to demonstrate that Munc18-1 EIEE-causing mutants form large polymers that coaggregate wild-type Munc18-1 in vitro and in cells. Surprisingly, Munc18-1 EIEE mutants also form Lewy body-like structures that contain α-synuclein (α-Syn). We reveal that Munc18-1 binds α-Syn, and its EIEE mutants coaggregate α-Syn. Likewise, removal of endogenous Munc18-1 increases the aggregative propensity of α-Syn(WT) and that of the Parkinson's disease-causing α-Syn(A30P) mutant, an effect rescued by Munc18-1(WT) expression, indicative of chaperone activity. Coexpression of the α-Syn(A30P) mutant with Munc18-1 reduced the number of α-Syn(A30P) aggregates. Munc18-1 mutations and haploinsufficiency may therefore trigger a pathogenic gain of function through both the corruption of native Munc18-1 and a perturbed chaperone activity for α-Syn leading to aggregation-induced neurodegeneration.
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Ye Jin
0000-0002-3022-7690
YJ
Chai
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia Single Molecule Sciences Centre, European Molecular Biology Laboratory Australia, The University of New South Wales, Sydney 2052, Australia.
Emma
0000-0001-9970-868X
E
Sierecki
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Vanesa M
0000-0003-4379-8502
VM
Tomatis
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Rachel S
0000-0003-1604-0253
RS
Gormal
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia Single Molecule Sciences Centre, European Molecular Biology Laboratory Australia, The University of New South Wales, Sydney 2052, Australia.
Nichole
N
Giles
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Isabel C
IC
Morrow
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Di
0000-0001-8058-5536
D
Xia
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Jürgen
0000-0001-8501-7896
J
Götz
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
Robert G
0000-0002-7494-5248
RG
Parton
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia.
Brett M
BM
Collins
Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia Single Molecule Sciences Centre, European Molecular Biology Laboratory Australia, The University of New South Wales, Sydney 2052, Australia f.meunier@uq.edu.au y.gambin@unsw.edu.au.
Yann
0000-0001-7378-8976
Y
Gambin
Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Frédéric A
0000-0001-6400-1107
FA
Meunier
D000818:Animals; D000831:Animals, Newborn; D005838:Genotype; D057895:Haploinsufficiency; D016631:Lewy Bodies / Q000378:metabolism / Q000473:pathology; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051938:Munc18 Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009410:Nerve Degeneration; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D016716:PC12 Cells; D010300:Parkinson Disease / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D066329:Protein Aggregates; D011485:Protein Binding; D011487:Protein Conformation; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D051844:alpha-Synuclein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D018832:Molecular Chaperones; D051938:Munc18 Proteins; D066329:Protein Aggregates; D011993:Recombinant Fusion Proteins; C497606:Snca protein, rat; C497939:Stxbp1 protein, rat; D051844:alpha-Synuclein