The ER-mitochondrial interface is central to calcium signaling, organellar dynamics, and lipid biosynthesis. The ER and mitochondrial membranes also host sources and targets of reactive oxygen ...species (ROS), but their local dynamics and relevance remained elusive since measurement and perturbation of ROS at the organellar interface has proven difficult. Employing drug-inducible synthetic ER-mitochondrial linkers, we overcame this problem and demonstrate that the ER-mitochondrial interface hosts a nanodomain of H2O2, which is induced by cytoplasmic Ca2+ spikes and exerts a positive feedback on calcium oscillations. H2O2 nanodomains originate from the mitochondrial cristae, which are compressed upon calcium signal propagation to the mitochondria, likely due to Ca2+-induced K+ and concomitant water influx to the matrix. Thus, ER-mitochondrial H2O2 nanodomains represent a component of inter-organelle communication, regulating calcium signaling and mitochondrial activities.
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•The ER-mitochondrial interface hosts a dynamic H2O2 nanodomain•ER-mitochondrial Ca2+ transfer stimulates ROS mobilization from mitochondria•The oxidized cristae volume is the source of interface H2O2 transients•H2O2 transients sensitize ER Ca2+ release to maintain Ca2+ oscillations
During Ca2+ signals, elevated Ca2+ microdomains form at the ER-mitochondrial interface. Booth et al. demonstrate that a nanodomain of H2O2 is also present. This is produced by Ca2+-induced mobilization of ROS from the mitochondrial cristae and functions to sensitize ER Ca2+ channels.
Nox/Duox NADPH oxidases are now considered the primary, regulated sources of reactive oxygen species (ROS). These enzymes are expressed in diverse cells and tissues, and their products are essential ...in several physiological settings. Knockout mouse models are instrumental in identifying the physiological functions of Nox/Duox enzymes as well as in exploring the impact of their pharmacological targeting on disease progression. The currently available data from experiments on knockout animals suggest that the lack of non-phagocytic Nox/Duox enzymes often modifies the course and phenotype in many disease models. Nevertheless, as illustrated by studies on Nox4-deficient animals, the absence of Nox-derived ROS can also lead to aggravated disease manifestation, reinforcing the need for a more balanced view on the role of ROS in health and disease.
NADPH oxidases: new kids on the block Geiszt, Miklós
Cardiovascular research,
2006-Jul-15, 2006-07-15, 20060715, Letnik:
71, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Reactive oxygen species (ROS) play a pivotal role in many physiological processes including host defense, hormone biosynthesis, fertilization and cellular signaling. Altered production of ROS has ...been implicated in the development of immunodeficiency, hypothyroidism and cardiovascular pathologies. In the last few years, several enzymes were identified at the molecular level, which are now thought to be responsible for ROS production observed in diverse tissues. These enzymes show a high degree of homology to the phagocytic NADPH oxidase and are now designated the Nox family of NADPH oxidases. This review updates our knowledge on six new members of the Nox family: Nox1, Nox3, Nox4, Nox5, Duox1 and Duox2.
Peroxidase enzymes can oxidize a multitude of substrates in diverse biological processes. According to the latest phylogenetic analysis, there are four major heme peroxidase superfamilies. In this ...review, we focus on certain members of the cyclooxygenase-peroxidase superfamily (also labeled as animal heme peroxidases) and their connection to specific NADPH oxidase enzymes which provide H
O
for the one- and two-electron oxidation of various peroxidase substrates. The family of NADPH oxidases is a group of enzymes dedicated to the production of superoxide and hydrogen peroxide. There is a handful of known and important physiological functions where one of the seven known human NADPH oxidases plays an essential role. In most of these functions NADPH oxidases provide H
O
for specific heme peroxidases and the concerted action of the two enzymes is indispensable for the accomplishment of the biological function. We discuss human and other metazoan examples of such cooperation between oxidases and peroxidases and analyze the biological importance of their functional interaction. We also review those oxidases and peroxidases where this kind of partnership has not been identified yet.
Members of the NOX/DUOX family of NADPH oxidases are responsible for regulated ROS production in diverse cells and tissues. Detection of NOX/DUOX proteins at the protein level remains an important ...challenge in the field. Here we report the development and characterization of a novel anti-NOX5 monoclonal antibody, which recognizes the human NOX5 protein in both Western blot, immunocytochemistry, and histochemistry applications. With the help of the antibody we could successfully detect both heterologously and endogenously expressed NOX5 in mammalian cells. Furthermore, we could also detect NOX5 protein in the human spleen, testis, and ovary. Immunohistochemical studies on human testis revealed that NOX5 localized to spermatogenic cells. This expression pattern was also supported by the result of in silico analysis of single-cell RNA sequencing data that indicated that NOX5 protein is present in developing spermatids and spermatocytes. Mature spermatozoa, however, did not contain detectable NOX5. In the human ovary, both immunostaining and single-cell RNA sequencing suggest that NOX5 is expressed in interstitial fibroblasts and theca cells. We also analyzed vascular cells for the presence of NOX5 and we found that NOX5 expression is a fairly specific feature of splenic endothelial cells.
Formation of intra- and intermolecular disulfide bonds is an essential step in the synthesis of secretory proteins. In eukaryotic cells, this process occurs in the endoplasmic reticulum (ER) and ...requires an oxidative environment with the action of several chaperones and folding catalysts. During protein folding, Ero1p oxidizes protein disulfide isomerase (PDI), which then directly catalyzes the formation of disulfide bonds in folding proteins. Recent cell-free studies suggest that the terminal electron acceptor in the pathway is molecular oxygen, with the resulting formation of hydrogen peroxide (H(2)O(2)). We report for the first time the measurement of ER H(2)O(2) level in live cells. By targeting a fluorescent protein-based H(2)O(2) sensor to various intracellular compartments, we show that the ER has the highest level of H(2)O(2), and this high concentration is well confined to the lumen of the organelle. Manipulation of the Ero1-Lalpha level--either by overexpression or by siRNA-mediated inhibition--caused parallel changes in luminal H(2)O(2), proving that the activity of Ero1-Lalpha results in H(2)O(2) formation in the ER. We also found that calcium mobilization from intracellular stores induces a decrease in ER H(2)O(2) level, suggesting a complex interplay between redox and calcium signaling in the mammalian ER.
Peroxidasins: novel players in tissue genesis Péterfi, Zalán; Geiszt, Miklós
Trends in biochemical sciences (Amsterdam. Regular ed.),
07/2014, Letnik:
39, Številka:
7
Journal Article
Recenzirano
Stabilization of extracellular matrix by protein crosslinking is a universal and essential process in multicellular organisms. Recent findings revealed that peroxidasin, a unique heme-peroxidase, ...produces hypohalides to support matrix synthesis. Unexpectedly, the highly reactive and potentially damaging hypohalides mediate the formation of sulfilimine bonds between adjacent collagen IV protomers. This crosslink is a fundamental feature of basal membranes, defining peroxidasin-dependent oxidant generation and sulfilimine crosslink formation as an elemental mechanism of tissue biogenesis.
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