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Molecular pathophysiology of human MICU1 deficiency

Lookup NU author(s): Dr Ana TopfORCiD, Professor Hanns Lochmuller, Professor Rita HorvathORCiD, Dr Andreas Roos

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© 2021 British Neuropathological SocietyAims: MICU1 encodes the gatekeeper of the mitochondrial Ca2+ uniporter, MICU1 and biallelic loss-of-function mutations cause a complex, neuromuscular disorder in children. Although the role of the protein is well understood, the precise molecular pathophysiology leading to this neuropaediatric phenotype has not been fully elucidated. Here we aimed to obtain novel insights into MICU1 pathophysiology. Methods: Molecular genetic studies along with proteomic profiling, electron-, light- and Coherent anti-Stokes Raman scattering microscopy and immuno-based studies of protein abundances and Ca2+ transport studies were employed to examine the pathophysiology of MICU1 deficiency in humans. Results: We describe two patients carrying MICU1 mutations, two nonsense (c.52C>T; p.(Arg18*) and c.553C>T; p.(Arg185*)) and an intragenic exon 2-deletion presenting with ataxia, developmental delay and early onset myopathy, clinodactyly, attention deficits, insomnia and impaired cognitive pain perception. Muscle biopsies revealed signs of dystrophy and neurogenic atrophy, severe mitochondrial perturbations, altered Golgi structure, vacuoles and altered lipid homeostasis. Comparative mitochondrial Ca2+ transport and proteomic studies on lymphoblastoid cells revealed that the [Ca2+] threshold and the cooperative activation of mitochondrial Ca2+ uptake were lost in MICU1-deficient cells and that 39 proteins were altered in abundance. Several of those proteins are linked to mitochondrial dysfunction and/or perturbed Ca2+ homeostasis, also impacting on regular cytoskeleton (affecting Spectrin) and Golgi architecture, as well as cellular survival mechanisms. Conclusions: Our findings (i) link dysregulation of mitochondrial Ca2+ uptake with muscle pathology (including perturbed lipid homeostasis and ER–Golgi morphology), (ii) support the concept of a functional interplay of ER–Golgi and mitochondria in lipid homeostasis and (iii) reveal the vulnerability of the cellular proteome as part of the MICU1-related pathophysiology.


Publication metadata

Author(s): Kohlschmidt N, Elbracht M, Czech A, Hausler M, Phan V, Topf A, Huang K-T, Bartok A, Eggermann K, Zippel S, Eggermann T, Freier E, Gross C, Lochmuller H, Horvath R, Hajnoczky G, Weis J, Roos A

Publication type: Article

Publication status: Published

Journal: Neuropathology and Applied Neurobiology

Year: 2021

Volume: 47

Issue: 6

Pages: 840-855

Print publication date: 01/10/2021

Online publication date: 11/01/2021

Acceptance date: 14/09/2020

Date deposited: 09/01/2024

ISSN (print): 0305-1846

ISSN (electronic): 1365-2990

Publisher: Blackwell Publishing Ltd

URL: https://doi.org/10.1111/nan.12694

DOI: 10.1111/nan.12694

Data Access Statement: The proteomic data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the data set identifier PXD008867.

PubMed id: 33428302


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Funding

Funder referenceFunder name
#21466
031A360E
109915/Z/15/ZWellcome Trust
2012-305121
309548
950-232279
Canadian Institutes of Health Research
Canada Foundation for Innovation
Canada Research Chairs program
CFI-JELF 38412
deCODE genetics
European Community’s Seventh Framework Programme
FDN-167281
European Regional Development Fund (ERDF)
European Research Council
FP7/2007-2013
French Muscular Dystrophy Association (AFM-Téléthon)
Leibniz-Research-Cluster
Medical Research Council
MR/N027302/1Medical Research Council (MRC)
MR/N025431/1Medical Research Council (MRC)
Muscular Dystrophy Canada
Newton Fund
NMD4C
Wellcome

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