Optical Imaging Reveals Liver Metabolic Perturbations in Mblac1 Knockout Mice.

Abstract

Metabolic changes have been extensively documented in brain tissue undergoing neurodegeneration, including Parkinson's disease and Alzheimer's disease (AD). Mutations in the C. elegans swip-10 gene result in dopamine (DA) dependent motor dysfunction accompanied by DA neuron degeneration. Recently, the putative human ortholog of swip-10 (MBLAC1) was implicated as a risk factor in AD, that like PD, has been associated with mitochondrial dysfunction. Interestingly, the AD risk associated with MBLAC1 arises in subjects with cardiovascular morbidity, suggesting the possibility of a broader functional insult arising from reduced MBLAC1 protein expression, and one possibly linked to metabolic alterations. Our current studies, utilizing Mblac1 knockout (KO) mice, seeks to determine whether mitochondrial respiration is affected in peripheral tissues of these animals in this model. To initiate these studies, we quantified the levels of mitochondrial coenzymes, NADH, FAD, and their redox ratio (NADH/FAD, RR) in the livers of wild type (WT) mice and their homozygous KO littermates, using 3D optical cryo-imaging. We found that Mblac1 KO mice exhibited a greater oxidized redox state compared to WT mice. When compared to the WT group, the redox ratio of KO mice was decreased by 46.32%, driven predominantly by significantly lower NADH levels (more oxidized state). We speculate that, as seen with C. elegans swip-10 mutants, that loss of MBLAC1 protein results in deficits in tricarboxylic acid cycle (TCA) production of NADH and FAD TCA that leads to diminished cellular ATP production and oxidative stress. Such observations are consistent with changes that in the central nervous system (CNS) could support neurodegeneration and in the periphery account for comorbidities.