Proctor, EC, Turton, N, Boan, EJ, Bennett, E, Philips, S, Heaton, R and Hargreaves, I (2020) The Effect of Methylmalonic Acid Treatment on Human Neuronal Cell Coenzyme Q10 Status and Mitochondrial Function. International Journal of Molecular Sciences, 21 (23). ISSN 1422-0067

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Abstract

Methylmalonic acidemia is an inborn metabolic disease of propionate catabolism, biochemically characterized by accumulation of methylmalonic acid (MMA) to millimolar concentrations in tissues and body fluids. However, MMA’s role in the pathophysiology of the disorder and its status as a “toxic intermediate” is unclear, despite evidence for its ability to compromise antioxidant defenses and induce mitochondrial dysfunction. Coenzyme Q10 (CoQ10) is a prominent electron carrier in the mitochondrial respiratory chain (MRC) and a lipid-soluble antioxidant which has been reported to be deficient in patient-derived fibroblasts and renal tissue from an animal model of the disease. However, at present, it is uncertain which factors are responsible for inducing this CoQ10 deficiency or the effect of this deficit in CoQ10 status on mitochondrial function. Therefore, in this study, we investigated the potential of MMA, the principal metabolite that accumulates in methylmalonic acidemia, to induce a cellular CoQ10 deficiency. In view of the severe neurological presentation of patients with this condition, human neuroblastoma SH-SY5Y cells were used as a neuronal cell model for this investigation. Following treatment with pathological concentrations of MMA (>0.5 mM), we found a significant (p = 0.0087) ~75% reduction in neuronal cell CoQ10 status together with a significant (p = 0.0099) decrease in MRC complex II–III activity at higher concentrations (>2 mM). The deficits in neuronal CoQ10 status and MRC complex II–III activity were associated with a loss of cell viability. However, no significant impairment of mitochondrial membrane potential (ΔΨm) was detectable. These findings indicate the potential of pathological concentrations of MMA to induce a neuronal cell CoQ10 deficiency with an associated loss of MRC complex II–III activity. However, in the absence of an impairment of ΔΨm, the contribution this potential deficit in cellular CoQ10 status makes towards the disease pathophysiology methylmalonic acidemia has yet to be fully elucidated.

Item Type:	Article
Uncontrolled Keywords:	0399 Other Chemical Sciences, 0604 Genetics, 0699 Other Biological Sciences
Subjects:	R Medicine > RM Therapeutics. Pharmacology
Divisions:	Pharmacy & Biomolecular Sciences
Publisher:	MDPI AG
Date Deposited:	02 Dec 2020 11:06
Last Modified:	04 Sep 2021 06:17
DOI or ID number:	10.3390/ijms21239137
URI:	https://researchonline.ljmu.ac.uk/id/eprint/14107

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