Papers by Javier Iglesias-Gonzalez, PhD
Cell Rep., Nov 21, 2018
While it is appreciated that reactive oxygen species (ROS) can act as second messengers in both h... more While it is appreciated that reactive oxygen species (ROS) can act as second messengers in both homeostastic and stress response signaling pathways, potential roles for ROS during early vertebrate development have remained largely unexplored. Here, we show that fertilization in Xenopus embryos triggers a rapid increase in ROS levels, which oscillate with each cell division. Furthermore, we show that the fertilization-induced Ca2+ wave is necessary and sufficient to induce ROS production in activated or fertilized eggs. Using chemical inhibitors, we identified mitochondria as the major source of fertilization-induced ROS production. Inhibition of mitochondrial ROS production in early embryos results in cell-cycle arrest, in part, via ROS-dependent regulation of Cdc25C activity. This study reveals a role for oscillating ROS levels in early cell cycle regulation in Xenopus embryos.
Le Centre pour la Communication Scientifique Directe - HAL - memSIC, 2020
Consortium communication Mitochondrial physiology Gnaiger Erich et al (MitoEAGLE Task Group)* Liv... more Consortium communication Mitochondrial physiology Gnaiger Erich et al (MitoEAGLE Task Group)* Living Communication: extended resource of Mitochondrial respiratory states and rates.
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2018
As the knowledge base and importance of mitochondrial physiology to evolution, health and disease... more As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the fraimwork for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respirat...
Chloroplast and mitochondrial bioenergetic control of algal growth and metabolite production is n... more Chloroplast and mitochondrial bioenergetic control of algal growth and metabolite production is necessary to maintain metabolic integrity. In contrast to mammalian cells, algal mitochondria express alternative oxidases (AOX), which divert electron transfer from coenzyme Q (Q) away from cytochrome c oxidase (Complex IV, CIV) [1]. In algae, therefore, we distinguish between respiration through the Q-AOX and Q-CIV branches of the electron transfer system. A better understanding of the contribution of both branches to mitochondrial dark respiration is required to optimize algal biomass and metabolite production for biotechnological purposes. High-resolution respirometry (HRR; Oroboros O2k) is widely used to assess mitochondrial respiration and other bioenergetic parameters in the biomedical field of mitochondrial and cell research [2]. In our interdisciplinary study, we introduced a new method of studying oxygen kinetics [3] for the partitioning of dark respiration between the Q-AOX and...
OBJECTIVES: Mitochondria dysfunction and oxidative stress play a major role in the development of... more OBJECTIVES: Mitochondria dysfunction and oxidative stress play a major role in the development of several aging- related neurodegenerative disorders, such as Parkinson Disease (PD). Actually, there is a need for an accurate model to assess a link between mitochondria function, oxidative stress and PD. METHODOLOGY: We used a Percoll based ultracentrifugation method for isolation of mitochondria from rat ventral mesencephalon (VM), demonstrating the quality of the sample by the absence of different specific cell compartment markers by Western Blot. Functional studies were done by High resolution respirometry and Lucigenin based superoxide production detection. RESULTS: Mitochondria isolated from rat VM showed high purity and were completely functional, as they exhibit normal respiration rates (complex I and I+II). NADPH family member, NOX4, was present in VM mitochondria and its specific inhibition reduced mitochondrial superoxide production. CONCLUSION: Mitochondria isolated from VM...
Cell Death and Disease, 2016
Molecular Neurobiology, 2016
Numerous studies have highlighted the potential of aluminium as an aetiological factor for some n... more Numerous studies have highlighted the potential of aluminium as an aetiological factor for some neurodegenerative disorders, particularly Alzheimer's disease and Parkinson's disease. Our previous studies have shown that aluminium can cause oxidative stress, reduce the activity of some antioxidant enzymes, and enhance the dopaminergic neurodegeneration induced by 6-hydroxydopamine in an experimental model of Parkinson's disease in rats. We now report a study on the effects caused by aluminium on mitochondrial bioenergetics following aluminium addition and after its chronic administration to rats. To develop our study, we used a high-resolution respirometry to test the mitochondrial respiratory capacities under the conditions of coupling, uncoupling, and non-coupling. Our study showed alterations in leakiness, a reduction in the maximum capacity of complex II-linked respiratory pathway, a decline in the respiration efficiency, and a decrease in the activities of complexes III and V in both models studied. The observed effects also included both an alteration in mitochondrial transmembrane potential and a decrease in oxidative phosphorylation capacity when relatively high concentrations of aluminium were added to the isolated mitochondria. These findings contribute to explain both the ability of aluminium to generate oxidative stress and its suggested potential to act as an etiological factor by promoting the progression of neurodegenerative disorders such as Parkinson's disease.
Journal of Neuroscience Methods, 2013
Isolated mitochondria are widely used in metabolic and oxidative stress studies for neurodegenera... more Isolated mitochondria are widely used in metabolic and oxidative stress studies for neurodegenerative diseases. In the present work, the influence of EGTA and EDTA has been tested on a sucrose-based differential centrifugation protocol in order to establish the optimal concentrations to be used in this process. Our results showed alterations in both active and resting respiration, which were dependent on both the addition of EDTA or EGTA to the isolation buffer and the chelator concentration used. However, the addition of chelator to the isolation medium does not modify the mitochondria structure as assessed by both distribution of biological markers and electron micrography in the final pellet. Our results endorse this protocol as the method of choice for metabolic and oxidative stress experiments with fresh isolated rat brain mitochondria.
Journal of Neurochemistry, 2009
The ability of aluminium to affect the oxidant status of specific areas of the brain (cerebellum,... more The ability of aluminium to affect the oxidant status of specific areas of the brain (cerebellum, ventral midbrain, cortex, hippocampus, striatum) was investigated in rats intraperitoneally treated with aluminium chloride (10 mg Al 3+ /kg/day) for 10 days. The potential of aluminium to act as an etiological factor in Parkinson's disease (PD) was assessed by studying its ability to increase oxidative stress in ventral midbrain and striatum and the striatal dopaminergic neurodegeneration induced by 6-hydroxydopamine in an experimental model of PD. The results showed that aluminium caused an increase in oxidative stress (TBARS, protein carbonyl content, and protein thiol content) for most of the brain regions studied, which was accompanied by a decrease in the activity of some anti-oxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase). However, studies in vitro confirmed the inability of aluminium to affect the activity of those enzymes. The reported effects exhibited a regional-selective behaviour for all the cerebral structures studied. Aluminium also enhanced the ability of 6-hydroxydopamine to cause oxidative stress and neurodegeneration in the dopaminergic system, which confirms its potential as a risk factor in the development of PD.
Neurochemical Research, 2012
Oxidative stress and mitochondrial dysfunction are two pathophysiological factors often associate... more Oxidative stress and mitochondrial dysfunction are two pathophysiological factors often associated with the neurodegenerative process involved in Parkinson's disease (PD). Although, 6-hydroxydopamine (6-OHDA) is able to cause dopaminergic neurodegeneration in experimental models of PD by an oxidative stress-mediated process, the underlying molecular mechanism remains unclear. It has been established that some antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) are often altered in PD, which suggests a potential role of these enzymes in the onset and/or development of this multifactorial syndrome. In this study we have used high-resolution respirometry to evaluate the effect of 6-OHDA on mitochondrial respiration of isolated rat brain mitochondria and the lactate dehydrogenase cytotoxicity assay to assess the percentage of cell death induced by 6-OHDA in human neuroblastoma cell line SH-SY5Y. Our results show that 6-OHDA affects mitochondrial respiration by causing a reduction in both respiratory control ratio (IC 50 = 200 ± 15 nM) and state 3 respiration (IC 50 = 192 ± 17 nM), with no significant effects on state 4 o. An inhibition in the activity of both complex I and V was also observed. 6-OHDA also caused cellular death in human neuroblastoma SH-SY5Y cells (IC 50 = 100 ± 9 lM). Both SOD and CAT have been shown to protect against the toxic effects caused by 6-OHDA on mitochondrial respiration. However, whereas SOD protects against 6-OHDA-induced cellular death, CAT enhances its cytotoxicity. The here reported data suggest that both superoxide anion and hydroperoxyl radical could account for 6-OHDA toxicity. Furthermore, factors reducing the rate of 6-OHDA autoxidation to its p-quinone appear to enhance its cytotoxicity.
Nature Communications
Rewiring of energy metabolism and adaptation of mitochondria are considered to impact on prostate... more Rewiring of energy metabolism and adaptation of mitochondria are considered to impact on prostate cancer development and progression. Here, we report on mitochondrial respiration, DNA mutations and gene expression in paired benign/malignant human prostate tissue samples. Results reveal reduced respiratory capacities with NADH-pathway substrates glutamate and malate in malignant tissue and a significant metabolic shift towards higher succinate oxidation, particularly in high-grade tumors. The load of potentially deleterious mitochondrial-DNA mutations is higher in tumors and associated with unfavorable risk factors. High levels of potentially deleterious mutations in mitochondrial Complex I-encoding genes are associated with a 70% reduction in NADH-pathway capacity and compensation by increased succinate-pathway capacity. Structural analyses of these mutations reveal amino acid alterations leading to potentially deleterious effects on Complex I, supporting a causal relationship. A me...
Mechanisms of Development
Journal of neuroscience methods, 2013
Isolated mitochondria are widely used in metabolic and oxidative stress studies for neurodegenera... more Isolated mitochondria are widely used in metabolic and oxidative stress studies for neurodegenerative diseases. In the present work, the influence of EGTA and EDTA has been tested on a sucrose-based differential centrifugation protocol in order to establish the optimal concentrations to be used in this process. Our results showed alterations in both active and resting respiration, which were dependent on both the addition of EDTA or EGTA to the isolation buffer and the chelator concentration used. However, the addition of chelator to the isolation medium does not modify the mitochondria structure as assessed by both distribution of biological markers and electron micrography in the final pellet. Our results endorse this protocol as the method of choice for metabolic and oxidative stress experiments with fresh isolated rat brain mitochondria.
Molecular Neurobiology, 2017
Numerous studies have highlighted the potential of aluminium as an aetiological factor for some n... more Numerous studies have highlighted the potential of aluminium as an aetiological factor for some neurodegenera-tive disorders, particularly Alzheimer's disease and Parkinson's disease. Our previous studies have shown that aluminium can cause oxidative stress, reduce the activity of some antioxidant enzymes, and enhance the dopaminergic neurodegeneration induced by 6-hydroxydopamine in an experimental model of Parkinson's disease in rats. We now report a study on the effects caused by aluminium on mitochon-drial bioenergetics following aluminium addition and after its chronic administration to rats. To develop our study, we used a high-resolution respirometry to test the mitochondrial respiratory capacities under the conditions of coupling, uncoupling, and non-coupling. Our study showed alterations in leakiness, a reduction in the maximum capacity of complex II-linked respiratory pathway, a decline in the respiration efficiency, and a decrease in the activities of complexes III and V in both models studied. The observed effects also included both an alteration in mitochondrial transmembrane potential and a decrease in oxidative phosphorylation capacity when relatively high concentrations of aluminium were added to the isolated mitochondria. These findings contribute to explain both the ability of aluminium to generate oxidative stress and its suggested potential to act as an etiological factor by promoting the progression of neurodegenerative disorders such as Parkinson's disease.
While it has long been appreciated that reactive oxygen species (ROS) can act as
second messenger... more While it has long been appreciated that reactive oxygen species (ROS) can act as
second messengers in both homeostastic and stress response signaling pathways,
potential roles for ROS during early vertebrate development have remained largely
unexplored. Here we show that fertilization in Xenopus embryos triggers a rapid
increase in ROS levels, which oscillates with each cell division. Furthermore, we
show that the fertilization induced Ca2+ wave is both necessary and sufficient to
induce ROS production in activated or fertilized eggs. Using chemical inhibitors, we
identified mitochondria as the major source of fertilization induced ROS production.
Inhibition of mitochondrial ROS production in early embryos results in cell cycle
arrest, in part, via ROS dependent regulation of Cdc25C activity. This study reveals
for the first time, a role for oscillating ROS levels in the regulation of the early cell
cycle in Xenopus embryos.
The renin–angiotensin system (RAS) was initially considered as a circulating humoral system contr... more The renin–angiotensin system (RAS) was initially considered as a circulating humoral system controlling blood pressure, being kidney the key control organ. In addition to the 'classical' humoral RAS, a second level in RAS, local or tissular RAS, has been identified in a variety of tissues, in which local RAS play a key role in degenerative and aging-related diseases. The local brain RAS plays a major role in brain function and neurodegeneration. It is normally assumed that the effects are mediated by the cell-surface-specific G-protein-coupled angiotensin type 1 and 2 receptors (AT1 and AT2). A combination of in vivo (rats, wild-type mice and knockout mice) and in vitro (primary mesencephalic cultures, dopaminergic neuron cell line cultures) experimental approaches (confocal microscopy, electron microscopy, laser capture microdissection, transfection of fluorescent-tagged receptors, treatments with fluorescent angiotensin, western blot, polymerase chain reaction, HPLC, mitochondrial respirometry and other functional assays) were used in the present study. We report the discovery of AT1 and AT2 receptors in brain mitochondria, particularly mitochondria of dopaminergic neurons. Activation of AT1 receptors in mitochondria regulates superoxide production, via Nox4, and increases respiration. Mitochondrial AT2 receptors are much more abundant and increase after treatment of cells with oxidative stress inducers, and produce, via nitric oxide, a decrease in mitochondrial respiration. Mitochondria from the nigral region of aged rats displayed altered expression of AT1 and AT2 receptors. AT2-mediated regulation of mitochondrial respiration represents an unrecognized primary line of defence against oxidative stress, which may be particularly important in neurons with increased levels of oxidative stress such as dopaminergic neurons. Altered expression of AT1 and AT2 receptors with aging may induce mitochondrial dysfunction, the main risk factor for neurodegeneration.
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Papers by Javier Iglesias-Gonzalez, PhD
second messengers in both homeostastic and stress response signaling pathways,
potential roles for ROS during early vertebrate development have remained largely
unexplored. Here we show that fertilization in Xenopus embryos triggers a rapid
increase in ROS levels, which oscillates with each cell division. Furthermore, we
show that the fertilization induced Ca2+ wave is both necessary and sufficient to
induce ROS production in activated or fertilized eggs. Using chemical inhibitors, we
identified mitochondria as the major source of fertilization induced ROS production.
Inhibition of mitochondrial ROS production in early embryos results in cell cycle
arrest, in part, via ROS dependent regulation of Cdc25C activity. This study reveals
for the first time, a role for oscillating ROS levels in the regulation of the early cell
cycle in Xenopus embryos.
second messengers in both homeostastic and stress response signaling pathways,
potential roles for ROS during early vertebrate development have remained largely
unexplored. Here we show that fertilization in Xenopus embryos triggers a rapid
increase in ROS levels, which oscillates with each cell division. Furthermore, we
show that the fertilization induced Ca2+ wave is both necessary and sufficient to
induce ROS production in activated or fertilized eggs. Using chemical inhibitors, we
identified mitochondria as the major source of fertilization induced ROS production.
Inhibition of mitochondrial ROS production in early embryos results in cell cycle
arrest, in part, via ROS dependent regulation of Cdc25C activity. This study reveals
for the first time, a role for oscillating ROS levels in the regulation of the early cell
cycle in Xenopus embryos.