An Experimental Approach to Address the Functional Relationship between Antioxidant Enzymes and Mitochondrial Respiratory Complexes

Mitochondrial Dysfunction in Skeletal Muscle of Rotenone-Induced Rat Model of Parkinson's Disease: SC-Nanophytosomes as Therapeutic Approach

The development of new therapeutic options for Parkinson's disease (PD) requires formulations able to mitigate both brain degeneration and motor dysfunctions. SC-Nanophytosomes, an oral mitochondria-targeted formulation developed with Codium tomentosum membrane polar lipids and elderberry anthocyanin-enriched extract, promote significant brain benefits on a rotenone-induced rat model of PD. In the present work, the effects of SC-Nanophytosome treatment on the skeletal muscle tissues are disclosed. It is unveiled that the rotenone-induced PD rat model exhibits motor disabilities and skeletal muscle tissues with deficient activity of mitochondrial complexes I and II along with small changes in antioxidant enzyme activity and skeletal muscle lipidome. SC-Nanophytosome treatment mitigates the impairment of complexes I and II activity, improving the mitochondrial respiratory chain performance at levels that surpass the control. Therefore, SC-Nanophytosome competence to overcome the PD-related motor disabilities should be also associated with its positive outcomes on skeletal muscle mitochondria. Providing a cellular environment with more reduced redox potential, SC-Nanophytosome treatment improves the skeletal muscle tissue's ability to deal with oxidative stress stimuli. The PD-related small changes on skeletal muscle lipidome were also counteracted by SC-Nanophytosome treatment. Thus, the present results reinforces the concept of SC-Nanophytosomes as a mitochondria-targeted therapy to address the neurodegeneration challenge.

Mitochondrial Diabetes Is Associated with the ND4 G11696A Mutation

Type 2 diabetes mellitus (T2DM) is a common endocrine disorder which remains a large challenge for clinicians. Previous studies have suggested that mitochondrial dysfunction plays an active role in T2DM progression, but a detailed mechanism is still elusive. In the current study, two Han Chinese families with maternally inherited T2DM were evaluated using clinical, genetic, molecular, and biochemical analyses. The mitochondrial genomes were PCR amplified and sequenced. Phylogenetic and bioinformatic analyses were used to assess the potential pathogenicity of mitochondrial DNA (mtDNA) mutations. Interestingly, the matrilineal relatives of these pedigrees exhibited variable severity of T2DM, in particular, the age at onset of T2DM varied from 26 to 65 years, with an average of 49 years. Sequence analysis revealed the presence of ND4 G11696A mutation, which resulted in the substitution of an isoleucine for valine at amino acid (AA) position 312. Indeed, this mutation was present in homoplasmy only in the maternal lineage, not in other members of these families, as well as 200 controls. Furthermore, the m.C5601T in the tRNA^Ala and novel m.T5813C in the tRNA^Cys, showing high evolutional conservation, may contribute to the phenotypic expression of ND4 G11696A mutation. In addition, biochemical analysis revealed that cells with ND4 G11696A mutation exhibited higher levels of reactive oxygen species (ROS) productions than the controls. In contrast, the levels of mitochondrial membrane potential (MMP), ATP, mtDNA copy number (mtDNA-CN), Complex I activity, and NAD⁺/NADH ratio significantly decreased in cell lines carrying the m.G11696A and tRNA mutations, suggesting that these mutations affected the respiratory chain function and led to mitochondrial dysfunction that was involved in T2DM. Thus, our study broadened the clinical phenotypes of m.G11696A mutation.