Biology subjects

Lopez, L. C.

Publications and source records attributed to Lopez, L. C..

3 recordsLinked to original sources

bioRxiv2026

The lack of peroxisomal Glycolate Oxidases 1 and 2 influences mitochondrial electron transport chain and its redox state under control and cadmium stress

The production of reactive oxygen species (ROS) in response to cadmium (Cd) has been extensively studied, demonstrating that they play a key role in the plants response to this heavy metal. While the role of enzymes like RBOHs has been thoroughly studied, the function of other ROS-producing enzymes, such as peroxisomal glycolate oxidase (GOX), remains largely overlooked. Peroxisomal GOX is a core metabolic enzyme of the photorespiratory pathway occurring in chloroplasts, mitochondria and peroxisomes. Using Arabidopsis (Arabidopsis thaliana) mutants lacking the main peroxisomal GOX genes, GOX1 (gox1-1) and GOX2 (gox2-1) we explored their function in plant response to Cd. Although photosynthetic capacity appears to be affected to the same extent in both mutants under control and Cd stress conditions, GOX2 seems to play a greater role in ROS production in response to the metal. Transcriptomic analyses on WT and gox2-1 pointed to the mitochondrial electron transport chain (mETC) as a target of Cd stress. We further investigated the individual GOX1 and GOX2 functions in mETC regulation and redox state. Although oxidative ratio of mitochondria was higher in both mutants, it was more pronounced in the absence of GOX1. Furthermore, the mETC is affected in both mutants but the regulation of its components differs in each mutant. These results point out the different functions of the two photorespiratory GOX isoforms in Arabidopsis, leading to a better understanding of the photorespiratory pathway.

plant biology↗

bioRxiv2024

Time-resolved mitochondrial-focused screening identifies regulatory components of oxidative metabolism

Defects in mitochondrial oxidative metabolism contribute to various genetic inherited disorders, termed mitochondrial diseases, with limited treatment options. Given the lack of functional annotation for numerous mitochondrial proteins, there is a necessity for an extensive gene inventory related to mitochondrial function, with special interest in Oxidative Phosphorylation (OXPHOS). To address this gap, we developed a CRISPR/Cas9 loss-of-function library targeting nuclear-encoded mitochondrial genes and conducted galactose-based screenings at various time points to uncover novel regulators of mitochondrial function. Our study resulted in a gene catalog essential for mitochondrial oxidative metabolism, and constructed a dynamic timeline mapping a broad network of mitochondrial pathways, with a particular focus on the OXPHOS complexes. Computational analysis pinpointed RTN4IP1 and ECHS1 as key genes strongly associated with OXPHOS and whose mutations are associated with mitochondrial diseases in humans. RTN4IP1 was found to be crucial for mitochondrial respiration, with complexome profiling revealing its role as an assembly factor required for the complete assembly of complex I. Furthermore, we discovered that ECHS1 controls oxidative metabolism independently of its canonical function in fatty acid oxidation. Deletion of ECHS1 leads to reduced catabolism of branched-chain amino acids (BCAAs), which impairs the activity of lipoic acid-dependent enzymes such as pyruvate dehydrogenase (PDH). This deleterious phenotype can be rescued by restricting valine intake or catabolism in ECHS1-deficient cells.

molecular biology↗

bioRxiv2021

β-RA targets mitochondrial metabolism and adipogenesis, leading to therapeutic benefits against CoQ deficiency and age-related overweight

Primary mitochondrial diseases are caused by mutations in mitochondrial or nuclear genes, leading to abnormal function of specific mitochondrial pathways. Mitochondrial dysfunction is also a secondary event in more common pathophysiological conditions, such as obesity and metabolic syndrome. In both cases, the improvement and management of mitochondrial homeostasis remains challenging. Here, we show that beta-resorcylic acid ({beta}-RA), a natural phenolic compound, competes in vivo with 4-hydroxybenzoic acid, the natural precursor of Coenzyme Q biosynthesis. This leads to a decrease of demethoxyubiquinone, an intermediate metabolite of CoQ biosynthesis that is abnormally accumulated in Coq9R239X mice. As a consequence, {beta}-RA rescues the phenotype of Coq9R239X mice, a model of primary mitochondrial encephalopathy. Moreover, we observe that long-term treatment with {beta}-RA also reduces the size and content of the white adipose tissue (WAT) that is normally accumulated during aging in wild-type mice, leading to a prevention of hepatic steatosis and an increase in survival at the old stage of life. The reduction in WAT content is due to a decrease in adipogenesis, an adaptation of the mitochondrial proteome in the kidneys, and a stimulation of glycolysis and acetyl-CoA metabolism. Therefore, our results demonstrate that {beta}-RA acts through different cellular mechanisms, with effects on mitochondrial metabolism, and it may be used for the treatment of primary Coenzyme Q deficiency, overweight, and hepatic steatosis.

physiology↗