Communication between mitochondria and nucleus: Putative role for VDAC in reduction/oxidation mechanism

AbstractVoltage dependent anion channel (VDAC) was identified in 1976 and since that time has been extensively studied. It is well known that VDAC transports metabolites across the outer mitochondrial membrane. The simple transport function is indispensable for proper mitochondria functions and, consequently for cell activity, and makes VDAC crucial for a range of cellular processes including ATP rationing, Ca2+ homeostasis and apoptosis execution. Here, we review recent data obtained for Saccharomyces cerevisiae cells used as a model system concerning the putative role of VDAC in communication between mitochondria and the nucleus. The S. cerevisiae VDAC isoform known as VDAC1 (termed here YVDAC) mediates the cytosol reduction/oxidation (redox) state that contributes to regulation of expression and activity of cellular proteins including proteins that participate in protein import into mitochondria and antioxidant enzymes. Simultaneously, copper-and-zinc-containing superoxide dismutase (CuZnSOD) plays an important role in controlling YVDAC activity and expression levels. Thus, it is proposed that VDAC constitutes an important component of a regulatory mechanism based on the cytosol redox state

Verification of Hypsibius exemplaris Gąsiorek et al., 2018 (Eutardigrada; Hypsibiidae) application in anhydrobiosis research

Anhydrobiosis is considered to be an adaptation of important applicative implications because it enables resistance to the lack of water. The phenomenon is still not well understood at molecular level. Thus, a good model invertebrate species for the research is required. The best known anhydrobiotic invertebrates are tardigrades (Tardigrada), considered to be toughest animals in the world. Hypsibius. exemplaris is one of the best studied tardigrade species, with its name “exemplaris” referring to the widespread use of the species as a laboratory model for various types of research. However, available data suggest that anhydrobiotic capability of the species may be overestimated. Therefore, we determined anhydrobiosis survival by Hys. exemplaris specimens using three different anhydrobiosis protocols. We also checked ultrastructure of storage cells within formed dormant structures (tuns) that has not been studied yet for Hys. exemplaris. These cells are known to support energetic requirements of anhydrobiosis. The obtained results indicate that Hys. exemplaris appears not to be a good model species for anhydrobiosis research. Introductio

Methadone induces necrotic-like cell death in SH-SY5Y cells by an impairment of mitochondrial ATP synthesis

Methadone is a widely used therapeutic opioid in narcotic addiction and neuropathic pain syndromes. Oncologists regularly use methadone as a long-lasting analgesic. Recently it has also been proposed as a promising agent in leukemia therapy, especially when conventional therapies are not effective. Nevertheless, numerous reports indicate a negative impact on human cognition with chronic exposure to opiates. Thus, clarification of methadone toxicity is required. In SH-SY5Y cells we found that high concentrations of methadone were required to induce cell death. Methadone-induced cell death seems to be related to necrotic processes rather than typical apoptosis. Cell cultures challenged with methadone presented alterations in mitochondrial outer membrane permeability. A mechanism that involves Bax translocation to the mitochondria was observed, accompanied with cytochrome c release. Furthermore, no participation of known protein regulators of apoptosis such as Bcl-XL and p53 was observed. Interestingly, methadone induced cell death took place by a caspases-independent pathway; perhaps due to its ability to induce a drastic depletion in cellular ATP levels. Therefore, we studied the effect of methadone on isolated rat liver mitochondria. We observed that methadone caused mitochondrial uncoupling, coinciding with the ionophoric properties of methadone, but did not cause swelling of the organelles. Overall, the effects observed for cells in the presence of supratherapeutic doses of methadone may result from a “bioenergetic crisis.” A decreased level of cellular energy may predispose cells to necrotic-like cell death

Phylogenetic Analysis of Mitochondrial Outer Membrane β-Barrel Channels

Transport of molecules across mitochondrial outer membrane is pivotal for a proper function of mitochondria. The transport pathways across the membrane are formed by ion channels that participate in metabolite exchange between mitochondria and cytoplasm (voltage-dependent anion-selective channel, VDAC) as well as in import of proteins encoded by nuclear genes (Tom40 and Sam50/Tob55). VDAC, Tom40, and Sam50/Tob55 are present in all eukaryotic organisms, encoded in the nuclear genome, and have β-barrel topology. We have compiled data sets of these protein sequences and studied their phylogenetic relationships with a special focus on the position of Amoebozoa. Additionally, we identified these protein-coding genes in Acanthamoeba castellanii and Dictyostelium discoideum to complement our data set and verify the phylogenetic position of these model organisms. Our analysis show that mitochondrial β-barrel channels from Archaeplastida (plants) and Opisthokonta (animals and fungi) experienced many duplication events that resulted in multiple paralogous isoforms and form well-defined monophyletic clades that match the current model of eukaryotic evolution. However, in representatives of Amoebozoa, Chromalveolata, and Excavata (former Protista), they do not form clearly distinguishable clades, although they locate basally to the plant and algae branches. In most cases, they do not posses paralogs and their sequences appear to have evolved quickly or degenerated. Consequently, the obtained phylogenies of mitochondrial outer membrane β-channels do not entirely reflect the recent eukaryotic classification system involving the six supergroups: Chromalveolata, Excavata, Archaeplastida, Rhizaria, Amoebozoa, and Opisthokonta

The mechanism of minocycline influence on the yeast Saccharomyces cerevisiae cells. The cytoprotective effect

Wydział BiologiiMinocycklina jest powszechnie stosowanym antybiotykiem z grupy tetracyklin. Co ciekawe, dostępne dane wskazują na właściwości cytoprotekcyjne minocykliny oraz możliwość ich wykorzystania w terapii różnych chorób. W związku z tym, w ramach niniejszej pracy przeprowadzono eksperymenty mające na celu wskazanie elementów istotnych dla cytoprotekcyjnego działania minocykliny. Wykazałem, iż cytoprotekcyjne działanie minocykliny w przypadku komórek drożdży Saccharomyces cerevisiae poddanych działaniu uniwersalnego czynnika proapoptotycznego (H2O2) wymaga obecności kanału VDAC (zależny od potencjału kanał o selektywności anionowej) i związane jest z modulacją poziomu sprzężenia energetycznego, co wskazuje na oddziaływanie na stan funkcjonalny mitochondriów. Kanał VDAC jest bowiem odpowiedzialny za transport metabolitów przez zewnętrzną błonę mitochondrialną, co jest procesem niezbędnym dla prawidłowego funkcjonowania mitochondriów. Wykazałem także, że w przypadku mitochondriów izolowanych z komórek różnych organizmów, minocyklina wykazuje aktywność rozprzęgacza (w zakresie stężeń mikromolarnych) lub czynnika wzmacniającego sprzężenie energetyczne (w zakresie stężeń nanomoralnych). Co więcej, wyniki badań polegających na analizie wpływu minocykliny na kanał VDAC poddany rekonstytucji, jak i analizie wpływu różnych czynników na właściwości minocykliny i analiza bioinformatyczna wskazują na możliwość bezpośredniego oddziaływania minocykliny na kanał VDAC. Zatem, kanał VDAC, jak i stężenie minocykliny wydają się być istotnymi elementami w cytoprotekcyjnym działaniu minocykliny.Minocycline is a commonly applied antibiotic of the tetracycline family. Interestingly, the available data indicate that minocycline displays cytoprotective properties that could be used in the treatment of various diseases. Therefore, in the present study experiments were performed to identify elements that are relevant for the cytoprotective properties. It has been shown that in the case of the yeast Saccharomyces cerevisiae cells pretreated with the universal pro-apoptotic factor (H2O2), the cytoprotective effect of minocycline requires the presence of the VDAC channel (voltage-dependent anion-selective channel) and is associated with modulation of the level of the energy coupling, which indicates the effect on the functional state of mitochondria. Accordingly, the VDAC channel is responsible for the transport of metabolites across the mitochondrial outer membrane, which is essential to mitochondria functioning. It has been also showed that in the case of mitochondria isolated from cells of different organisms, minocycline displays either uncoupler (micromolar concentration range) or the energy coupling reinforcing agent (nanomolar concentration range) activity. Moreover, the obtained results concerning the analysis of minocycline effect on the reconstituted VDAC channel and analysis of the impact of various factors on properties of minocycline as well as bioinformatic analysis suggest strongly a direct interaction between minocycline and the VDAC channel. Thus, the channel VDAC and the concentration of minocycline appear to be important for minocycline cytoprotective activity

The mechanism of minocycline influence on the yeast Saccharomyces cerevisiae cells. The cytoprotective effect

Wydział BiologiiMinocycklina jest powszechnie stosowanym antybiotykiem z grupy tetracyklin. Co ciekawe, dostępne dane wskazują na właściwości cytoprotekcyjne minocykliny oraz możliwość ich wykorzystania w terapii różnych chorób. W związku z tym, w ramach niniejszej pracy przeprowadzono eksperymenty mające na celu wskazanie elementów istotnych dla cytoprotekcyjnego działania minocykliny. Wykazałem, iż cytoprotekcyjne działanie minocykliny w przypadku komórek drożdży Saccharomyces cerevisiae poddanych działaniu uniwersalnego czynnika proapoptotycznego (H2O2) wymaga obecności kanału VDAC (zależny od potencjału kanał o selektywności anionowej) i związane jest z modulacją poziomu sprzężenia energetycznego, co wskazuje na oddziaływanie na stan funkcjonalny mitochondriów. Kanał VDAC jest bowiem odpowiedzialny za transport metabolitów przez zewnętrzną błonę mitochondrialną, co jest procesem niezbędnym dla prawidłowego funkcjonowania mitochondriów. Wykazałem także, że w przypadku mitochondriów izolowanych z komórek różnych organizmów, minocyklina wykazuje aktywność rozprzęgacza (w zakresie stężeń mikromolarnych) lub czynnika wzmacniającego sprzężenie energetyczne (w zakresie stężeń nanomoralnych). Co więcej, wyniki badań polegających na analizie wpływu minocykliny na kanał VDAC poddany rekonstytucji, jak i analizie wpływu różnych czynników na właściwości minocykliny i analiza bioinformatyczna wskazują na możliwość bezpośredniego oddziaływania minocykliny na kanał VDAC. Zatem, kanał VDAC, jak i stężenie minocykliny wydają się być istotnymi elementami w cytoprotekcyjnym działaniu minocykliny.Minocycline is a commonly applied antibiotic of the tetracycline family. Interestingly, the available data indicate that minocycline displays cytoprotective properties that could be used in the treatment of various diseases. Therefore, in the present study experiments were performed to identify elements that are relevant for the cytoprotective properties. It has been shown that in the case of the yeast Saccharomyces cerevisiae cells pretreated with the universal pro-apoptotic factor (H2O2), the cytoprotective effect of minocycline requires the presence of the VDAC channel (voltage-dependent anion-selective channel) and is associated with modulation of the level of the energy coupling, which indicates the effect on the functional state of mitochondria. Accordingly, the VDAC channel is responsible for the transport of metabolites across the mitochondrial outer membrane, which is essential to mitochondria functioning. It has been also showed that in the case of mitochondria isolated from cells of different organisms, minocycline displays either uncoupler (micromolar concentration range) or the energy coupling reinforcing agent (nanomolar concentration range) activity. Moreover, the obtained results concerning the analysis of minocycline effect on the reconstituted VDAC channel and analysis of the impact of various factors on properties of minocycline as well as bioinformatic analysis suggest strongly a direct interaction between minocycline and the VDAC channel. Thus, the channel VDAC and the concentration of minocycline appear to be important for minocycline cytoprotective activity