In vitro studies in VCP-associated multisystem proteinopathy suggest altered mitochondrial bioenergetics.
Mitochondrial dysfunction has recently been implicated as an underlying factor to several common neurodegenerative diseases, including Parkinson's disease, Alzheimer's and amyotrophic lateral sclerosis (ALS). Valosin containing protein (VCP)-associated multisystem proteinopathy is a new hereditary disorder associated with inclusion body myopathy, Paget disease of bone (PDB), frontotemporal dementia (FTD) and ALS. VCP has been implicated in several transduction pathways including autophagy, apoptosis and the PINK1/Parkin cascade of mitophagy. In this report, we characterized VCP patient and mouse fibroblasts/myoblasts to examine their mitochondrial dynamics and bioenergetics. Using the Seahorse XF-24 technology, we discovered decreased spare respiratory capacity (measurement of extra ATP that can be produced by oxidative phosphorylation in stressful conditions) and increased ECAR levels (measurement of glycolysis), and proton leak in VCP human fibroblasts compared with age- and sex-matched unaffected first degree relatives. We found decreased levels of ATP and membrane potential, but higher mitochondrial enzyme complexes II+III and complex IV activities in the patient VCP myoblasts when compared to the values of the control cell lines. These results suggest that mutations in VCP affect the mitochondria's ability to produce ATP, thereby resulting in a compensatory increase in the cells' mitochondrial complex activity levels. Thus, this novel in vitro model may be useful in understanding the pathophysiology and discovering new drug targets of mitochondrial dynamics and physiology to modify the clinical phenotype in VCP and related multisystem proteinopathies (MSP).
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA. Electronic address: a.nalbandian@uci.edu.
Angèle
A
Nalbandian
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA.
Katrina J
KJ
Llewellyn
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA.
Arianna
A
Gomez
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA.
Naomi
N
Walker
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA.
Hailing
H
Su
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA.
Andrew
A
Dunnigan
Department of Ophthalmology, Gavin Herbert Eye Institute, University of California-Irvine, Irvine, CA 92697, USA.
Marilyn
M
Chwa
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA.
Jouni
J
Vesa
Department of Ophthalmology, Gavin Herbert Eye Institute, University of California-Irvine, Irvine, CA 92697, USA; Department of Pathology and Laboratory Medicine, University of California- Irvine, Irvine, CA 92697, USA.
M C
MC
Kenney
Department of Pediatrics, Division of Genetics and Genomic Medicine, University of California-Irvine, Irvine, CA 92697, USA. Electronic address: vkimonis@uci.edu.
Virginia E
VE
Kimonis
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004195:Disease Models, Animal; D045222:Electron Transport Chain Complex Proteins / Q000032:analysis; D004734:Energy Metabolism; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D032446:Myoblasts / Q000378:metabolism; D019636:Neurodegenerative Diseases / Q000473:pathology*; D057165:Proteostasis Deficiencies / Q000473:pathology*; D000074405:Valosin Containing Protein
D018797:Cell Cycle Proteins; D045222:Electron Transport Chain Complex Proteins; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C000614178:VCP protein, human; D000074405:Valosin Containing Protein; C000614179:Vcp protein, mouse
ALS; Frontotemporal dementia; Inclusion body myopathy; Mitochondrial bioenergetics; Paget's disease of the bone; Valosin containing protein