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EMBO Mol Med. 2017 Jul;9(7):967-984. doi: 10.15252/emmm.201607058.

MSTO1 is a cytoplasmic pro-mitochondrial fusion protein, whose mutation induces myopathy and ataxia in humans.

Author information

1
MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.
2
Institute of Genomic Medicine and Rare Disorders, Semmelweis University, Budapest, Hungary.
3
Department of Physiology, Semmelweis University, Budapest, Hungary.
4
Department of Biochemistry and Molecular Biology, University of Debrecen, Debrecen, Hungary.
5
MitoCare Center for Mitochondrial Imaging Research and Diagnostics, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA gyorgy.hajnoczky@jefferson.edu.

Abstract

The protein MSTO1 has been localized to mitochondria and linked to mitochondrial morphology, but its specific role has remained unclear. We identified a c.22G > A (p.Val8Met) mutation of MSTO1 in patients with minor physical abnormalities, myopathy, ataxia, and neurodevelopmental impairments. Lactate stress test and myopathological results suggest mitochondrial dysfunction. In patient fibroblasts, MSTO1 mRNA and protein abundance are decreased, mitochondria display fragmentation, aggregation, and decreased network continuity and fusion activity. These characteristics can be reversed by genetic rescue. Short-term silencing of MSTO1 in HeLa cells reproduced the impairment of mitochondrial morphology and dynamics observed in the fibroblasts without damaging bioenergetics. At variance with a previous report, we find MSTO1 to be localized in the cytoplasmic area with limited colocalization with mitochondria. MSTO1 interacts with the fusion machinery as a soluble factor at the cytoplasm-mitochondrial outer membrane interface. After plasma membrane permeabilization, MSTO1 is released from the cells. Thus, an MSTO1 loss-of-function mutation is associated with a human disorder showing mitochondrial involvement. MSTO1 likely has a physiologically relevant role in mitochondrial morphogenesis by supporting mitochondrial fusion.

KEYWORDS:

MSTO1; misato; mitochondria; mitochondrial disease; mitochondrial fusion

PMID:
28554942
PMCID:
PMC5494519
DOI:
10.15252/emmm.201607058
[Indexed for MEDLINE]
Free PMC Article

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