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Abstract
Mutations in the human mitochondrial genome are known to cause an array of diverse disorders, most of which are maternally inherited, and all of which are associated with defects in oxidative energy metabolism. It is now emerging that somatic mutations in mitochondrial DNA (mtDNA) are also linked to other complex traits, including neurodegenerative diseases, ageing and cancer. Here we discuss insights into the roles of mtDNA mutations in a wide variety of diseases, highlighting the interesting genetic characteristics of the mitochondrial genome and challenges in studying its contribution to pathogenesis.
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202
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Ludueña RF. A Hypothesis on the Origin and Evolution of Tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 302:41-185. [DOI: 10.1016/b978-0-12-407699-0.00002-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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203
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Shoshan-Barmatz V, Mizrachi D, Keinan N. Oligomerization of the Mitochondrial Protein VDAC1. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 117:303-34. [DOI: 10.1016/b978-0-12-386931-9.00011-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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204
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Shoshan-Barmatz V, Mizrachi D. VDAC1: from structure to cancer therapy. Front Oncol 2012; 2:164. [PMID: 23233904 PMCID: PMC3516065 DOI: 10.3389/fonc.2012.00164] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2012] [Accepted: 10/24/2012] [Indexed: 12/14/2022] Open
Abstract
Here, we review current evidence pointing to the function of VDAC1 in cell life and death, and highlight these functions in relation to cancer. Found at the outer mitochondrial membrane, VDAC1 assumes a crucial position in the cell, controlling the metabolic cross-talk between mitochondria and the rest of the cell. Moreover, its location at the boundary between the mitochondria and the cytosol enables VDAC1 to interact with proteins that mediate and regulate the integration of mitochondrial functions with other cellular activities. As a metabolite transporter, VDAC1 contributes to the metabolic phenotype of cancer cells. This is reflected by VDAC1 over-expression in many cancer types, and by inhibition of tumor development upon silencing VDAC1 expression. Along with regulating cellular energy production and metabolism, VDAC1 is also a key protein in mitochondria-mediated apoptosis, participating in the release of apoptotic proteins and interacting with anti-apoptotic proteins. The involvement of VDAC1 in the release of apoptotic proteins located in the inter-membranal space is discussed, as is VDAC1 oligomerization as an important step in apoptosis induction. VDAC also serves as an anchor point for mitochondria-interacting proteins, some of which are also highly expressed in many cancers, such as hexokinase (HK), Bcl2, and Bcl-xL. By binding to VDAC, HK provides both metabolic benefit and apoptosis-suppressive capacity that offers the cell a proliferative advantage and increases its resistance to chemotherapy. VDAC1-based peptides that bind specifically to HK, Bcl2, or Bcl-xL abolished the cell’s abilities to bypass the apoptotic pathway. Moreover, these peptides promote cell death in a panel of genetically characterized cell lines derived from different human cancers. These and other functions point to VDAC1 as a rational target for the development of a new generation of therapeutics.
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Affiliation(s)
- Varda Shoshan-Barmatz
- Department of Life Sciences, Ben-Gurion University of the Negev Beer-Sheva, Israel ; The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev Beer-Sheva, Israel
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205
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EBV up-regulates cytochrome c through VDAC1 regulations and decreases the release of cytoplasmic Ca2+ in the NPC cell line. Cell Biol Int 2012; 36:733-8. [PMID: 22497278 DOI: 10.1042/cbi20110368] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
EBV (Epstein-Barr virus) is considered to be a major factor that causes NPC (nasopharyngeal carcinoma), which is one of the sneakiest cancers frequently occurring in Southeast Asia and Southern China. Apoptosis and pro-apoptotic signals have been studied for decades; however, few have extended the prevailing view of EBV to its impact on NPC in perspective of apoptosis. One of the important proteins named VDAC1 (voltage-dependent anion protein 1) on the mitochondrial outer membrane controls the pro-apoptotic signals in mammalian cells. The impact of EBV infection on VDAC1 and related apoptotic signals remains unclear. In order to study the VDAC1's role in EBV-infected NPC cells, we employ siRNA (small interfering RNA) inhibition to analyse the release of Ca2+ and Cyto c (cytochrome c) signals in the cytoplasm, as they are important pro-apoptotic signals. The results show a decrease of Ca2+ release and up-regulation of Cyto c with EBV infection. After siRNA transfection, the dysregulation of Cyto c is neutralized, which is evidence that the level of Cyto c release in virus-infected NPC cells is the as same as that of non-infected NPC cells. This result indicates that EBV infection changes the cytoplasmic level of Cyto c through regulating VDAC1. In summary, this study reports that EBV changes the release of Ca2+ and Cyto c in the cytoplasm of NPC cells, and that Cyto c changes are mediated by VDAC1 regulation.
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206
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Mitochondrial porin Por1 and its homolog Por2 contribute to the positive control of Snf1 protein kinase in Saccharomyces cerevisiae. EUKARYOTIC CELL 2012; 11:1568-72. [PMID: 23104570 DOI: 10.1128/ec.00127-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Saccharomyces cerevisiae Snf1 is a member of the conserved Snf1/AMP-activated protein kinase (Snf1/AMPK) family involved in regulating responses to energy limitation, which is detected by mechanisms that include sensing adenine nucleotides. Mitochondrial voltage-dependent anion channel (VDAC) proteins, also known as mitochondrial porins, are conserved in eukaryotes from yeast to humans and play key roles in mediating mitochondrial outer membrane permeability to small metabolites, including ATP, ADP, and AMP. We previously recovered the yeast mitochondrial porin Por1 (yVDAC1) from a two-hybrid screen for Snf1-interacting proteins. Here, we present evidence that Snf1 interacts with Por1 and its homolog Por2 (yVDAC2). Cells lacking Por1 and Por2, but not respiratory-deficient rho(0) cells lacking the mitochondrial genome, exhibit reduced Snf1 activation loop phosphorylation in response to glucose limitation. Thus, Por1 and Por2 contribute to the positive control of Snf1 protein kinase. Physical proximity to the VDAC proteins and mitochondrial surface could facilitate Snf1's ability to sense energy limitation.
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207
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Mertins B, Psakis G, Grosse W, Back KC, Salisowski A, Reiss P, Koert U, Essen LO. Flexibility of the N-terminal mVDAC1 segment controls the channel's gating behavior. PLoS One 2012; 7:e47938. [PMID: 23110136 PMCID: PMC3479125 DOI: 10.1371/journal.pone.0047938] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 09/25/2012] [Indexed: 11/26/2022] Open
Abstract
Since the solution of the molecular structures of members of the voltage dependent anion channels (VDACs), the N-terminal α-helix has been the main focus of attention, since its strategic location, in combination with its putative conformational flexibility, could define or control the channel’s gating characteristics. Through engineering of two double-cysteine mVDAC1 variants we achieved fixing of the N-terminal segment at the bottom and midpoint of the pore. Whilst cross-linking at the midpoint resulted in the channel remaining constitutively open, cross-linking at the base resulted in an “asymmetric” gating behavior, with closure only at one electric field´s orientation depending on the channel’s orientation in the lipid bilayer. Additionally, and while the native channel adopts several well-defined closed states (S1 and S2), the cross-linked variants showed upon closure a clear preference for the S2 state. With native-channel characteristics restored following reduction of the cysteines, it is evident that the conformational flexibility of the N-terminal segment plays indeed a major part in the control of the channel’s gating behavior.
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Affiliation(s)
- Barbara Mertins
- Department of Chemistry, Philipps University Marburg, Marburg, Germany
| | - Georgios Psakis
- Department of Chemistry, Philipps University Marburg, Marburg, Germany
| | - Wolfgang Grosse
- Department of Chemistry, Philipps University Marburg, Marburg, Germany
| | | | | | - Philipp Reiss
- Department of Chemistry, Philipps University Marburg, Marburg, Germany
| | - Ulrich Koert
- Department of Chemistry, Philipps University Marburg, Marburg, Germany
| | - Lars-Oliver Essen
- Department of Chemistry, Philipps University Marburg, Marburg, Germany
- * E-mail:
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208
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Wang Y, Winters J, Subramaniam S. Functional classification of skeletal muscle networks. II. Applications to pathophysiology. J Appl Physiol (1985) 2012; 113:1902-20. [PMID: 23085957 DOI: 10.1152/japplphysiol.01515.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In our preceding companion paper (Wang Y, Winters J, Subramaniam S. J Appl Physiol. doi: 10.1152/japplphysiol.01514.2011), we used extensive expression profile data on normal human subjects, in combination with legacy knowledge to classify skeletal muscle function into four models, namely excitation-activation, mechanical, metabolic, and signaling-production model families. In this paper, we demonstrate how this classification can be applied to study two well-characterized myopathies: amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD). Using skeletal muscle profile data from ALS and DMD patients compared with that from normal subjects, normal young in the case of DMD, we delineate molecular mechanisms that are causative and consequential to skeletal muscle dysfunction. In ALS, our analysis establishes the metabolic role and specifically identifies the mechanisms of calcium dysregulation and defects in mitochondrial transport of materials as important for muscle dysfunction. In DMD, we illustrate how impaired mechanical function is strongly coordinated with other three functional networks, resulting in transformation of the skeletal muscle into hybrid forms as a compensatory mechanism. Our functional models also provide, in exquisite detail, the mechanistic role of myriad proteins in these four families in normal and disease function.
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Affiliation(s)
- Yu Wang
- Department of Bioengineering, University of California San Diego, La Jolla, California 92093-0412, USA
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209
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Zhou LY, Liu JP, Wang K, Gao J, Ding SL, Jiao JQ, Li PF. Mitochondrial function in cardiac hypertrophy. Int J Cardiol 2012; 167:1118-25. [PMID: 23044430 DOI: 10.1016/j.ijcard.2012.09.082] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 08/24/2012] [Accepted: 09/15/2012] [Indexed: 10/27/2022]
Abstract
Cardiac hypertrophic program is a chronic, complex process, and occurs in response to long-term increases of hemodynamic load related to a variety of pathophysiological conditions. Mitochondria, known as "the cellular power plants", occupy about one-third of cardiomyocyte volume and supply roughly 90% of the adenosine triphosphate (ATP). Impairment of energy metabolism has been regarded as one of the main pathogenesis of cardiac hypertrophy. Thus, we summarize here the molecular events of mitochondrial adaptations, including the mitochondrial genesis, ATP generation, ROS signaling and Ca(2+) homeostasis in cardiac hypertrophy, expecting that this effort will shed new light on understanding the maladaptive cardiac remodeling.
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Affiliation(s)
- Lu-Yu Zhou
- Division of Cardiovascular Research, State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
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210
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Abstract
Mitochondria have been classically characterized as organelles with responsibility for cellular energy production in the form of ATP, but they are also the organelles through which apoptotic signaling occurs. Cell stress stimuli can result in outer membrane permeabilization, after which mitochondria release numerous proteins involved in apoptotic signaling, including cytochrome c, apoptosis-inducing factor, endonuclease G, Smac/DIABLO and Omi/HtrA2. Cell fate is determined by signaling through apoptotic proteins within the Bcl-2 (B-cell lymphoma 2) protein family, which converges on mitochondria. Many cancerous cells display abnormal levels of Bcl-2 protein family member expression that results in defective apoptotic signaling. Alterations in bioenergetic function also contribute to cancer as well as numerous other disorders. Recent evidence indicates that several pro-apoptotic proteins localized within mitochondria, as well as proteins within the Bcl-2 protein family, can influence mitochondrial bioenergetic function. This review focuses on the emerging roles of these proteins in the control of mitochondrial activity.
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Affiliation(s)
- S M Kilbride
- Department of Physiology and Medical Physics, Centre for Systems Medicine, Royal College of Surgeons in Ireland, Dublin 2, Ireland
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211
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Zheleznova NN, Yang C, Ryan RP, Halligan BD, Liang M, Greene AS, Cowley AW. Mitochondrial proteomic analysis reveals deficiencies in oxygen utilization in medullary thick ascending limb of Henle in the Dahl salt-sensitive rat. Physiol Genomics 2012; 44:829-42. [PMID: 22805345 DOI: 10.1152/physiolgenomics.00060.2012] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The renal medullary thick ascending limb (mTAL) of the Dahl salt-sensitive (SS) rat is the site of enhanced NaCl reabsorption and excess superoxide production. In the present studies we isolated mitochondria from mTAL of SS and salt-resistant control strain SS.13(BN) rats on 0.4 and 8% salt diet for 7 days and performed a proteomic analysis. Purity of mTAL and mitochondria isolations exceeded 93.6 and 55%, respectively. Using LC/MS spectral analysis techniques we identified 96 mitochondrial proteins in four biological mTAL mitochondria samples, run in duplicate, as defined by proteins with a false discovery rate <5% and scan count ≥2. Seven of these 96 proteins, including IDH2, ACADM, SCOT, Hsp60, ATPA, EFTu, and VDAC2 were differentially expressed between the two rat strains. Oxygen consumption and high-resolution respirometry analyses showed that mTAL cells and the mitochondria in the outer medulla of SS rats fed high-salt diet exhibited lower rates of oxygen utilization compared with those from SS.13(BN) rats. These studies advance the conventional proteomic paradigm of focusing exclusively upon whole tissue homogenates to a focus upon a single cell type and specific subcellular organelle. The results reveal the importance of a largely unexplored role for deficiencies of mTAL mitochondrial metabolism and oxygen utilization in salt-induced hypertension and renal medullary oxidative stress.
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Affiliation(s)
- Nadezhda N Zheleznova
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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212
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Rostovtseva TK, Gurnev PA, Chen MY, Bezrukov SM. Membrane lipid composition regulates tubulin interaction with mitochondrial voltage-dependent anion channel. J Biol Chem 2012; 287:29589-98. [PMID: 22763701 DOI: 10.1074/jbc.m112.378778] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Elucidating molecular mechanisms by which lipids regulate protein function within biological membranes is critical for understanding the many cellular processes. Recently, we have found that dimeric αβ-tubulin, a subunit of microtubules, regulates mitochondrial respiration by blocking the voltage-dependent anion channel (VDAC) of mitochondrial outer membrane. Here, we show that the mechanism of VDAC blockage by tubulin involves tubulin interaction with the membrane as a critical step. The on-rate of the blockage varies up to 100-fold depending on the particular lipid composition used for bilayer formation in reconstitution experiments and increases with the increasing content of dioleoylphosphatidylethanolamine (DOPE) in dioleoylphosphatidylcholine (DOPC) bilayers. At physiologically low salt concentrations, the on-rate is decreased by the charged lipid. The off-rate of VDAC blockage by tubulin does not depend on the lipid composition. Using confocal fluorescence microscopy, we compared tubulin binding to the membranes of giant unilamellar vesicles (GUVs) made from DOPC and DOPC/DOPE mixtures. We found that detectable binding of the fluorescently labeled dimeric tubulin to GUV membranes requires the presence of DOPE. We propose that prior to the characteristic blockage of VDAC, tubulin first binds to the membrane in a lipid-dependent manner. We thus reveal a new potent regulatory role of the mitochondrial lipids in control of the mitochondrial outer membrane permeability and hence mitochondrial respiration through tuning VDAC sensitivity to blockage by tubulin. More generally, our findings give an example of the lipid-controlled protein-protein interaction where the choice of lipid species is able to change the equilibrium binding constant by orders of magnitude.
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Affiliation(s)
- Tatiana K Rostovtseva
- Program in Physical Biology, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, MD 20892, USA.
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213
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Reactive oxygen species in the signaling and adaptation of multicellular microbial communities. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:976753. [PMID: 22829965 PMCID: PMC3395218 DOI: 10.1155/2012/976753] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 05/24/2012] [Indexed: 02/07/2023]
Abstract
One of the universal traits of microorganisms is their ability to form multicellular structures, the cells of which differentiate and communicate via various signaling molecules. Reactive oxygen species (ROS), and hydrogen peroxide in particular, have recently become well-established signaling molecules in higher eukaryotes, but still little is known about the regulatory functions of ROS in microbial structures. Here we summarize current knowledge on the possible roles of ROS during the development of colonies and biofilms, representatives of microbial multicellularity. In Saccharomyces cerevisiae colonies, ROS are predicted to participate in regulatory events involved in the induction of ammonia signaling and later on in programmed cell death in the colony center. While the latter process seems to be induced by the total ROS, the former event is likely to be regulated by ROS-homeostasis, possibly H2O2-homeostasis between the cytosol and mitochondria. In Candida albicans biofilms, the predicted signaling role of ROS is linked with quorum sensing molecule farnesol that significantly affects biofilm formation. In bacterial biofilms, ROS induce genetic variability, promote cell death in specific biofilm regions, and possibly regulate biofilm development. Thus, the number of examples suggesting ROS as signaling molecules and effectors in the development of microbial multicellularity is rapidly increasing.
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214
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Rostovtseva TK, Bezrukov SM. VDAC inhibition by tubulin and its physiological implications. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1818:1526-35. [PMID: 22100746 PMCID: PMC3302949 DOI: 10.1016/j.bbamem.2011.11.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/24/2011] [Accepted: 11/02/2011] [Indexed: 11/23/2022]
Abstract
Regulation of mitochondrial outer membrane (MOM) permeability has dual importance: in normal metabolite and energy exchange between mitochondria and cytoplasm, and thus in control of respiration, and in apoptosis by release of apoptogenic factors into the cytosol. However, the mechanism of this regulation involving the voltage-dependent anion channel (VDAC), the major channel of MOM, remains controversial. For example, one of the long-standing puzzles was that in permeabilized cells, adenine nucleotide translocase is less accessible to cytosolic ADP than in isolated mitochondria. Still another puzzle was that, according to channel-reconstitution experiments, voltage regulation of VDAC is limited to potentials exceeding 30mV, which are believed to be much too high for MOM. We have solved these puzzles and uncovered multiple new functional links by identifying a missing player in the regulation of VDAC and, hence, MOM permeability - the cytoskeletal protein tubulin. We have shown that, depending on VDAC phosphorylation state and applied voltage, nanomolar to micromolar concentrations of dimeric tubulin induce functionally important reversible blockage of VDAC reconstituted into planar phospholipid membranes. The voltage sensitivity of the blockage equilibrium is truly remarkable. It is described by an effective "gating charge" of more than ten elementary charges, thus making the blockage reaction as responsive to the applied voltage as the most voltage-sensitive channels of electrophysiology are. Analysis of the tubulin-blocked state demonstrated that although this state is still able to conduct small ions, it is impermeable to ATP and other multi-charged anions because of the reduced aperture and inversed selectivity. The findings, obtained in a channel reconstitution assay, were supported by experiments with isolated mitochondria and human hepatoma cells. Taken together, these results suggest a previously unknown mechanism of regulation of mitochondrial energetics, governed by VDAC interaction with tubulin at the mitochondria-cytosol interface. Immediate physiological implications include new insights into serine/threonine kinase signaling pathways, Ca(2+) homeostasis, and cytoskeleton/microtubule activity in health and disease, especially in the case of the highly dynamic microtubule network which is characteristic of cancerogenesis and cell proliferation. In the present review, we speculate how these findings may help to identify new mechanisms of mitochondria-associated action of chemotherapeutic microtubule-targeting drugs, and also to understand why and how cancer cells preferentially use inefficient glycolysis rather than oxidative phosphorylation (Warburg effect). This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.
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Affiliation(s)
- Tatiana K Rostovtseva
- Laboratory of Physical and Structural Biology, Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Health, Bethesda, MD 20892, USA.
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215
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Vamecq J, Colet JM, Vanden Eynde JJ, Briand G, Porchet N, Rocchi S. PPARs: Interference with Warburg' Effect and Clinical Anticancer Trials. PPAR Res 2012; 2012:304760. [PMID: 22654896 PMCID: PMC3357561 DOI: 10.1155/2012/304760] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 02/15/2012] [Accepted: 02/19/2012] [Indexed: 02/07/2023] Open
Abstract
The metabolic/cell signaling basis of Warburg's effect ("aerobic glycolysis") and the general metabolic phenotype adopted by cancer cells are first reviewed. Several bypasses are adopted to provide a panoramic integrated view of tumoral metabolism, by attributing a central signaling role to hypoxia-induced factor (HIF-1) in the expression of aerobic glycolysis. The cancer metabolic phenotype also results from alterations of other routes involving ras, myc, p53, and Akt signaling and the propensity of cancer cells to develop signaling aberrances (notably aberrant surface receptor expression) which, when present, offer unique opportunities for therapeutic interventions. The rationale for various emerging strategies for cancer treatment is presented along with mechanisms by which PPAR ligands might interfere directly with tumoral metabolism and promote anticancer activity. Clinical trials using PPAR ligands are reviewed and followed by concluding remarks and perspectives for future studies. A therapeutic need to associate PPAR ligands with other anticancer agents is perhaps an important lesson to be learned from the results of the clinical trials conducted to date.
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Affiliation(s)
- Joseph Vamecq
- Inserm, HMNO, CBP, CHRU Lille, 59037 Lille, France
- Biochemistry and Molecular Biology, HMNO, CBP, CHRU Lille, 59037 Lille, France
| | - Jean-Marie Colet
- Department of Human Biology and Toxicology, Faculty of Medicine and Pharmacy, UMons, 7000 Mons, Belgium
| | | | - Gilbert Briand
- Biochemistry and Molecular Biology, HMNO, CBP, CHRU Lille, 59037 Lille, France
| | - Nicole Porchet
- Biochemistry and Molecular Biology, HMNO, CBP, CHRU Lille, 59037 Lille, France
| | - Stéphane Rocchi
- Inserm U1065, IFR 50, Mediterranean Center of Molecular Medicine, 06204 Nice, France
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216
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Cassimeris L, Silva VC, Miller E, Ton Q, Molnar C, Fong J. Fueled by microtubules: Does tubulin dimer/polymer partitioning regulate intracellular metabolism? Cytoskeleton (Hoboken) 2012; 69:133-43. [DOI: 10.1002/cm.21008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 01/11/2012] [Indexed: 11/07/2022]
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217
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Gergalova G, Lykhmus O, Kalashnyk O, Koval L, Chernyshov V, Kryukova E, Tsetlin V, Komisarenko S, Skok M. Mitochondria express α7 nicotinic acetylcholine receptors to regulate Ca2+ accumulation and cytochrome c release: study on isolated mitochondria. PLoS One 2012; 7:e31361. [PMID: 22359587 PMCID: PMC3281078 DOI: 10.1371/journal.pone.0031361] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 01/06/2012] [Indexed: 11/30/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that mediate synaptic transmission in the muscle and autonomic ganglia and regulate transmitter release in the brain. The nAChRs composed of α7 subunits are also expressed in non-excitable cells to regulate cell survival and proliferation. Up to now, functional α7 nAChRs were found exclusively on the cell plasma membrane. Here we show that they are expressed in mitochondria and regulate early pro-apoptotic events like cytochrome c release. The binding of α7-specific antibody with mouse liver mitochondria was revealed by electron microscopy. Outer membranes of mitochondria from the wild-type and β2−/− but not α7−/− mice bound α7 nAChR-specific antibody and toxins: FITC-labeled α-cobratoxin or Alexa 555-labeled α-bungarotoxin. α7 nAChR agonists (1 µM acetylcholine, 10 µM choline or 30 nM PNU-282987) impaired intramitochondrial Ca2+ accumulation and significantly decreased cytochrome c release stimulated with either 90 µM CaCl2 or 0.5 mM H2O2. α7-specific antagonist methyllicaconitine (50 nM) did not affect Ca2+ accumulation in mitochondria but attenuated the effects of agonists on cytochrome c release. Inhibitor of voltage-dependent anion channel (VDAC) 4,4′-diisothio-cyano-2,2′-stilbene disulfonic acid (0.5 µM) decreased cytochrome c release stimulated with apoptogens similarly to α7 nAChR agonists, and VDAC was co-captured with the α7 nAChR from mitochondria outer membrane preparation in both direct and reverse sandwich ELISA. It is concluded that α7 nAChRs are expressed in mitochondria outer membrane to regulate the VDAC-mediated Ca2+ transport and mitochondrial permeability transition.
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Affiliation(s)
- Galyna Gergalova
- Department of Molecular Immunology, Palladin Institute of Biochemistry, Kyiv, Ukraine
| | - Olena Lykhmus
- Department of Molecular Immunology, Palladin Institute of Biochemistry, Kyiv, Ukraine
| | - Olena Kalashnyk
- Department of Molecular Immunology, Palladin Institute of Biochemistry, Kyiv, Ukraine
| | - Lyudmyla Koval
- Department of Molecular Immunology, Palladin Institute of Biochemistry, Kyiv, Ukraine
| | - Volodymyr Chernyshov
- Department of Molecular Immunology, Palladin Institute of Biochemistry, Kyiv, Ukraine
| | - Elena Kryukova
- Department of Molecular Bases of Neurosignaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Victor Tsetlin
- Department of Molecular Bases of Neurosignaling, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Sergiy Komisarenko
- Department of Molecular Immunology, Palladin Institute of Biochemistry, Kyiv, Ukraine
| | - Maryna Skok
- Department of Molecular Immunology, Palladin Institute of Biochemistry, Kyiv, Ukraine
- * E-mail:
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218
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Teijido O, Ujwal R, Hillerdal CO, Kullman L, Rostovtseva TK, Abramson J. Affixing N-terminal α-helix to the wall of the voltage-dependent anion channel does not prevent its voltage gating. J Biol Chem 2012; 287:11437-45. [PMID: 22275367 DOI: 10.1074/jbc.m111.314229] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The voltage-dependent anion channel (VDAC) governs the free exchange of ions and metabolites between the mitochondria and the rest of the cell. The three-dimensional structure of VDAC1 reveals a channel formed by 19 β-strands and an N-terminal α-helix located near the midpoint of the pore. The position of this α-helix causes a narrowing of the cavity, but ample space for metabolite passage remains. The participation of the N-terminus of VDAC1 in the voltage-gating process has been well established, but the molecular mechanism continues to be debated; however, the majority of models entail large conformational changes of this N-terminal segment. Here we report that the pore-lining N-terminal α-helix does not undergo independent structural rearrangements during channel gating. We engineered a double Cys mutant in murine VDAC1 that cross-links the α-helix to the wall of the β-barrel pore and reconstituted the modified protein into planar lipid bilayers. The modified murine VDAC1 exhibited typical voltage gating. These results suggest that the N-terminal α-helix is located inside the pore of VDAC in the open state and remains associated with β-strand 11 of the pore wall during voltage gating.
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Affiliation(s)
- Oscar Teijido
- Program in Physical Biology, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA
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219
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Holmuhamedov EL, Czerny C, Beeson CC, Lemasters JJ. Ethanol suppresses ureagenesis in rat hepatocytes: role of acetaldehyde. J Biol Chem 2012; 287:7692-700. [PMID: 22228763 DOI: 10.1074/jbc.m111.293399] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We proposed previously that closure of voltage-dependent anion channels (VDAC) in the mitochondrial outer membrane after ethanol exposure leads to suppression of mitochondrial metabolite exchange. Because ureagenesis requires extensive mitochondrial metabolite exchange, we characterized the effect of ethanol and its metabolite, acetaldehyde (AcAld), on total and ureagenic respiration in cultured rat hepatocytes. Ureagenic substrates increased cellular respiration from 15.8 ± 0.9 nmol O(2)/min/10(6) cells (base line) to 29.4 ± 1.7 nmol O(2)/min/10(6) cells in about 30 min. Ethanol (0-200 mM) suppressed extra respiration after ureagenic substrates (ureagenic respiration) by up to 51% but not base line respiration. Urea formation also declined proportionately. Inhibition of alcohol dehydrogenase, cytochrome P450 2E1, and catalase with 4-methylpyrazole, trans-1,2-dichloroethylene, and 3-amino-1,2,3-triazole restored ethanol-suppressed ureagenic respiration by 46, 37, and 66%, respectively. By contrast, inhibition of aldehyde dehydrogenase with phenethyl isothiocyanate increased the inhibitory effect of ethanol on ureagenic respiration by an additional 60%. AcAld, an intermediate product of ethanol oxidation, suppressed ureagenic respiration with an apparent IC(50) of 125 μM. AcAld also inhibited entry of 3-kDa rhodamine-conjugated dextran in the mitochondrial intermembrane space of digitonin-permeabilized hepatocytes, indicative of VDAC closure. In conclusion, AcAld, derived from ethanol metabolism, suppresses ureagenesis in hepatocytes mediated by closure of VDAC.
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Affiliation(s)
- Ekhson L Holmuhamedov
- Center for Cell Death, Injury, and Regeneration, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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220
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Calcium signaling in cerebral vasoregulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:833-58. [PMID: 22453972 DOI: 10.1007/978-94-007-2888-2_37] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The tight coupling of regional neurometabolic activity with synaptic activity and regional cerebral blood perfusion constitutes a single functional unit, described generally as a neurovascular unit. This is central to any discussion of haemodynamic response linked to any neuronal activation. In normal as well as in pathologic conditions, neurons, astrocytes and endothelial cells of the vasculature interact to generate the complex activity-induced cerebral haemodynamic responses, with astrocytes not only partaking in the signaling but actually controlling it in many cases. Neurons and astrocytes have highly integrated signaling mechanisms, yet they form two separate networks. Bidirectional neuron-astrocyte interactions are crucial for the function and survival of the central nervous system. The primary purpose of such regulation is the homeostasis of the brain's microenvironment. In the maintenance of such homeostasis, astrocytic calcium response is a crucial variable in determining neurovascular control. Future work will be directed towards resolving the nature and extent of astrocytic calcium-mediated mechanisms for gene transcription, in modelling neurovascular control, and in determining calcium sensitive imaging assays that can capture disease variables.
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221
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Lemasters JJ, Holmuhamedov EL, Czerny C, Zhong Z, Maldonado EN. Regulation of mitochondrial function by voltage dependent anion channels in ethanol metabolism and the Warburg effect. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1536-44. [PMID: 22172804 DOI: 10.1016/j.bbamem.2011.11.034] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 11/22/2011] [Accepted: 11/28/2011] [Indexed: 12/18/2022]
Abstract
Voltage dependent anion channels (VDAC) are highly conserved proteins that are responsible for permeability of the mitochondrial outer membrane to hydrophilic metabolites like ATP, ADP and respiratory substrates. Although previously assumed to remain open, VDAC closure is emerging as an important mechanism for regulation of global mitochondrial metabolism in apoptotic cells and also in cells that are not dying. During hepatic ethanol oxidation to acetaldehyde, VDAC closure suppresses exchange of mitochondrial metabolites, resulting in inhibition of ureagenesis. In vivo, VDAC closure after ethanol occurs coordinately with mitochondrial uncoupling. Since acetaldehyde passes through membranes independently of channels and transporters, VDAC closure and uncoupling together foster selective and more rapid oxidative metabolism of toxic acetaldehyde to nontoxic acetate by mitochondrial aldehyde dehydrogenase. In single reconstituted VDAC, tubulin decreases VDAC conductance, and in HepG2 hepatoma cells, free tubulin negatively modulates mitochondrial membrane potential, an effect enhanced by protein kinase A. Tubulin-dependent closure of VDAC in cancer cells contributes to suppression of mitochondrial metabolism and may underlie the Warburg phenomenon of aerobic glycolysis. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.
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Affiliation(s)
- John J Lemasters
- Center for Cell Death, Injury & Regeneration, Medical University of South Carolina, Charleston, SC 29425, USA.
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222
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Homblé F, Krammer EM, Prévost M. Plant VDAC: facts and speculations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1486-501. [PMID: 22155681 DOI: 10.1016/j.bbamem.2011.11.028] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 11/12/2011] [Accepted: 11/22/2011] [Indexed: 01/01/2023]
Abstract
The voltage-dependent anion-selective channel (VDAC) is the most abundant protein in the mitochondrial outer membrane and the major transport pathway for a large variety of compounds ranging from ions to large polymeric molecules such as DNA and tRNA. Plant VDACs feature a secondary structure content and electrophysiological properties akin to those of VDACs from other organisms. They however undergo a specific regulation. The general importance of VDAC in plant physiology has only recently emerged. Besides their role in metabolite transport, plant VDACs are also involved in the programmed cell death triggered in response to biotic and abiotic stresses. Moreover, their colocalization in non-mitochondrial membranes suggests a diversity of function. This review summarizes our current understanding of the structure and function of plant VDACs. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.
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Affiliation(s)
- Fabrice Homblé
- Structure et Fontion des Membranes Biologiques, Centre de Biologie Structurale et de Bioinformatique, Université Libre de Bruxelles, Boulevard du Triomphe CP, Brussels, Belgium.
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223
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Rosenberg N, Rosenberg O, Weizman A, Leschiner S, Sakoury Y, Fares F, Soudry M, Weisinger G, Veenman L, Gavish M. In vitro mitochondrial effects of PK 11195, a synthetic translocator protein 18 kDa (TSPO) ligand, in human osteoblast-like cells. J Bioenerg Biomembr 2011; 43:739-46. [PMID: 22127435 DOI: 10.1007/s10863-011-9388-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 10/01/2011] [Indexed: 01/04/2023]
Abstract
The role of the TSPO in metabolism of human osteoblasts is unknown. We hypothesized that human osteoblast metabolism may be modulated by the TSPO. Therefore we evaluated the presence of TSPO in human osteoblast-like cells and the effect of its synthetic ligand PK 11195 on these cells. The presence of TSPO was determined by [(3)H]PK 11195 binding using Scatchard analysis: Bmax 7682 fmol/mg, Kd 9.24 nM. PK 11195 did not affect significantly cell proliferation, cell death, cellular viability, maturation, [(18)F]-FDG incorporation and hexokinase 2 gene expression or protein levels. PK 11195 exerted a suppressive effect on VDAC1 and caused an increase in TSPO gene expression or protein levels. In parallel there was an increase in mitochondrial mass, mitochondrial ATP content and a reduction in ΔΨm collapse. Thus, it appears that PK11195 (10(-5) M) stimulates mitochondrial activity in human osteoblast-like cells without affecting glycolytic activity and cell death.
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Affiliation(s)
- Nahum Rosenberg
- Department of Pharmacology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, POB 9649, Bat Galim, Haifa, 31096, Israel
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224
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Geula S, Naveed H, Liang J, Shoshan-Barmatz V. Structure-based analysis of VDAC1 protein: defining oligomer contact sites. J Biol Chem 2011; 287:2179-90. [PMID: 22117062 DOI: 10.1074/jbc.m111.268920] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The outer mitochondrial membrane protein, the voltage-dependent anion channel (VDAC), is increasingly implicated in the control of apoptosis. Oligomeric assembly of VDAC1 was shown to be coupled to apoptosis induction, with oligomerization increasing substantially upon apoptosis induction and inhibited by apoptosis blockers. In this study, structure- and computation-based selection of the predicated VDAC1 dimerization site, in combination with site-directed mutagenesis, cysteine replacement, and chemical cross-linking, were employed to identify contact sites between VDAC1 molecules in dimers and higher oligomers. The predicted weakly stable β-strands were experimentally found to represent the interfaces between VDAC1 monomers composing the oligomer. Replacing hydrophobic amino acids with charged residues in β-strands 1, 2, and 19 interfered with VDAC1 oligomerization. The proximity of β-strands 1, 2, and 19 within the VDAC1 dimer and the existence of other association sites involving β-strand 16 were confirmed when a cysteine was introduced at defined positions in cysteineless VDAC1 mutants, together with the use of cysteine-specific cross-linker bis(maleimido)ethane. Moreover, the results suggest that VDAC1 also exists as a dimer that upon apoptosis induction undergoes conformational changes and that its oligomerization proceeds through a series of interactions involving two distinct interfaces. Dissection of VDAC1 dimerization/oligomerization as presented here provides structural insight into the oligomeric status of cellular VDAC1 under physiological and apoptotic conditions.
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Affiliation(s)
- Shay Geula
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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225
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VDAC proteomics: post-translation modifications. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1520-5. [PMID: 22120575 DOI: 10.1016/j.bbamem.2011.11.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 11/03/2011] [Accepted: 11/11/2011] [Indexed: 01/07/2023]
Abstract
Voltage-dependent anion channels are abundant mitochondrial outer membrane proteins expressed in three isoforms, VDAC1-3, and are considered as "mitochondrial gatekeepers". Most tissues express all three isoforms. The functions of VDACs are several-fold, ranging from metabolite and energy exchange to apoptosis. Some of these functions depend on or are affected by interaction with other proteins in the cytosol and intermembrane space. Furthermore, the function of VDACs, as well as their interaction with other proteins, is affected by posttranslational modification, mainly phosphorylation. This review summarizes recent findings on posttranslational modification of VDACs and discusses the physiological outcome of these modifications. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.
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226
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McCommis KS, Baines CP. The role of VDAC in cell death: friend or foe? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1444-50. [PMID: 22062421 DOI: 10.1016/j.bbamem.2011.10.025] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 10/18/2011] [Accepted: 10/24/2011] [Indexed: 11/16/2022]
Abstract
As the voltage-dependent anion channel (VDAC) forms the interface between mitochondria and the cytosol, its importance in metabolism is well understood. However, research on VDAC's role in cell death is a rapidly growing field, unfortunately with much confusing and contradictory results. The fact that VDAC plays a role in outer mitochondrial membrane permeabilization is undeniable, however, the mechanisms behind this remain very poorly understood. In this review, we will summarize the studies that show evidence of VDAC playing a role in cell death. To begin, we will discuss the evidence for and against VDAC's involvement in mitochondrial permeability transition (MPT) and attempt to clarify that VDAC is not an essential component of the MPT pore (MPTP). Next, we will evaluate the remaining literature on VDAC in cell death which can be divided into three models: proapoptotic agents escaping through VDAC, VDAC homo- or hetero-oligomerization, or VDAC closure resulting in outer mitochondrial membrane permeabilization through an unknown pathway. We will then discuss the growing list of modulators of VDAC activity that have been associated with induction/protection against cell death. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.
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Affiliation(s)
- Kyle S McCommis
- Department of Biomedical Sciences, University of Missouri, USA
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227
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Sheldon KL, Maldonado EN, Lemasters JJ, Rostovtseva TK, Bezrukov SM. Phosphorylation of voltage-dependent anion channel by serine/threonine kinases governs its interaction with tubulin. PLoS One 2011; 6:e25539. [PMID: 22022409 PMCID: PMC3192757 DOI: 10.1371/journal.pone.0025539] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/06/2011] [Indexed: 01/16/2023] Open
Abstract
Tubulin was recently found to be a uniquely potent regulator of the voltage-dependent anion channel (VDAC), the most abundant channel of the mitochondrial outer membrane, which constitutes a major pathway for ATP/ADP and other metabolites across this membrane. Dimeric tubulin induces reversible blockage of VDAC reconstituted into a planar lipid membrane and dramatically reduces respiration of isolated mitochondria. Here we show that VDAC phosphorylation is an important determinant of its interaction with dimeric tubulin. We demonstrate that in vitro phosphorylation of VDAC by either glycogen synthase kinase-3β (GSK3β) or cAMP-dependent protein kinase A (PKA), increases the on-rate of tubulin binding to the reconstituted channel by orders of magnitude, but only for tubulin at the cis side of the membrane. This and the fact the basic properties of VDAC, such as single-channel conductance and selectivity, remained unaltered by phosphorylation allowed us to suggest the phosphorylation regions positioned on the cytosolic loops of VDAC and establish channel orientation in our reconstitution experiments. Experiments on human hepatoma cells HepG2 support our conjecture that VDAC permeability for the mitochondrial respiratory substrates is regulated by dimeric tubulin and channel phosphorylation. Treatment of HepG2 cells with colchicine prevents microtubule polymerization, thus increasing dimeric tubulin availability in the cytosol. Accordingly, this leads to a decrease of mitochondrial potential measured by assessing mitochondrial tetramethylrhodamine methyester uptake with confocal microscopy. Inhibition of PKA activity blocks and reverses mitochondrial depolarization induced by colchicine. Our findings suggest a novel functional link between serine/threonine kinase signaling pathways, mitochondrial respiration, and the highly dynamic microtubule network which is characteristic of cancerogenesis and cell proliferation.
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Affiliation(s)
- Kely L. Sheldon
- Laboratory of Physical and Structural Biology, Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Eduardo N. Maldonado
- Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - John J. Lemasters
- Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Tatiana K. Rostovtseva
- Laboratory of Physical and Structural Biology, Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sergey M. Bezrukov
- Laboratory of Physical and Structural Biology, Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
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228
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White spot syndrome virus induces metabolic changes resembling the warburg effect in shrimp hemocytes in the early stage of infection. J Virol 2011; 85:12919-28. [PMID: 21976644 DOI: 10.1128/jvi.05385-11] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The Warburg effect is an abnormal glycolysis response that is associated with cancer cells. Here we present evidence that metabolic changes resembling the Warburg effect are induced by a nonmammalian virus. When shrimp were infected with white spot syndrome virus (WSSV), changes were induced in several metabolic pathways related to the mitochondria. At the viral genome replication stage (12 h postinfection [hpi]), glucose consumption and plasma lactate concentration were both increased in WSSV-infected shrimp, and the key enzyme of the pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G6PDH), showed increased activity. We also found that at 12 hpi there was no alteration in the ADP/ATP ratio and that oxidative stress was lower than that in uninfected controls. All of these results are characteristic of the Warburg effect as it is present in mammals. There was also a significant decrease in triglyceride concentration starting at 12 hpi. At the late stage of the infection cycle (24 hpi), hemocytes of WSSV-infected shrimp showed several changes associated with cell death. These included the induction of mitochondrial membrane permeabilization (MMP), increased oxidative stress, decreased glucose consumption, and disrupted energy production. A previous study showed that WSSV infection led to upregulation of the voltage-dependent anion channel (VDAC), which is known to be involved in both the Warburg effect and MMP. Here we show that double-stranded RNA (dsRNA) silencing of the VDAC reduces WSSV-induced mortality and virion copy number. For these results, we hypothesize a model depicting the metabolic changes in host cells at the early and late stages of WSSV infection.
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229
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Renshaw GMC, Kutek AK, Grant GD, Anoopkumar-Dukie S. Forecasting elasmobranch survival following exposure to severe stressors. Comp Biochem Physiol A Mol Integr Physiol 2011; 162:101-12. [PMID: 21851860 DOI: 10.1016/j.cbpa.2011.08.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Revised: 07/25/2011] [Accepted: 08/01/2011] [Indexed: 02/07/2023]
Abstract
Current fishing practices and habitat degradation in most of the world's oceans pose significant threats to marine fish including elasmobranchs. The accurate prediction of survival probability for elasmobranchs subjected to prolonged immobilisation and diminished oxygen availability during capture and a vulnerable state post-release, is reliant on selecting a reliable set of biomarkers to profile as well as using them to design pre-release interventions which minimise elasmobranch death. The purpose of this review is: i) to make a case for the need to develop new biomarkers to use in conjunction with blood chemistry; ii) to briefly present the survival strategies used by other vertebrates subjected to diminished oxygen iii) to discuss new approaches to forecasting the effect that altered physiological and biochemical markers have on long-term survival with a particular emphasis on oxidative stress, the adenylate energy charge, heat shock protein expression and the capacity for repair, so that a more detailed profile of the qualities of elasmobranch survivorship can be constructed. In addition, the review will discuss the relevance of biomarkers to field samples as well as their incorporation into laboratory based research, aimed at providing physiological and biochemical data to inform conservation management.
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Affiliation(s)
- Gillian M C Renshaw
- Hypoxia and Ischemia Research Unit, Heart Foundation Research Centre and the School of Physiotherapy and Exercise Science, Griffith University, Gold Coast Campus, Queensland, 4222, Australia.
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230
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Chen DS, Chan KM. Differentially expressed proteins in zebrafish liver cells exposed to copper. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2011; 104:270-277. [PMID: 21641295 DOI: 10.1016/j.aquatox.2011.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 05/03/2011] [Accepted: 05/07/2011] [Indexed: 05/30/2023]
Abstract
Copper is an essential element for normal cellular processes in most eukaryotic organisms, but is toxic in excessive amounts. Different organisms vary in their ability to tolerate copper ions. We have previously studied the mechanism of copper toxicity to a copper tolerance cell line, Hepa T1, from tilapia using a proteomic approach. To compare the differences of proteins' regulation between copper tolerant and sensitive species after copper treatment, the zebrafish liver cell line (ZFL) was used as a model in this study to investigate the mechanism of copper toxicity to zebrafish. After conducting similar experimental procedures in previous Hepa T1 studies, 72 different proteins were identified to be regulated by Cu(2+) (100 μM and 200 μM). More than 50% of these proteins were also found with differentially expressed Hepa T1, indicating that the toxicity mechanism between zebrafish and tilapia was partially conserved. However, the regulation of several proteins in ZFL, related to the reactive oxygen species (ROS) effect, mitochondrion copper transportation and stress response, was quite different from that in tilapia.
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Affiliation(s)
- Dong Shi Chen
- Biochemistry and Environmental Science Programs, School of Life Sciences, Chinese University of Hong Kong, Sha Tin, NT, Hong Kong Special Administrative Region, China
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231
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Andrade IDS, Vianez-Júnior JL, Goulart CL, Homblé F, Ruysschaert JM, Almeida von Krüger WM, Bisch PM, de Souza W, Mohana-Borges R, Motta MCM. Characterization of a porin channel in the endosymbiont of the trypanosomatid protozoan Crithidia deanei. MICROBIOLOGY-SGM 2011; 157:2818-2830. [PMID: 21757490 DOI: 10.1099/mic.0.049247-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Crithidia deanei is a trypanosomatid protozoan that harbours a symbiotic bacterium. The partners maintain a mutualistic relationship, thus constituting an excellent model for studying metabolic exchanges between the host and the symbiont, the origin of organelles and cellular evolution. According to molecular analysis, symbionts of different trypanosomatid species share high identity and descend from a common ancestor, a β-proteobacterium of the genus Bordetella. The endosymbiont is surrounded by two membranes, like Gram-negative bacteria, but its envelope presents special features, since phosphatidylcholine is a major membrane component and the peptidoglycan layer is highly reduced, as described in other obligate intracellular bacteria. Like the process that generated mitochondria and plastids, the endosymbiosis in trypanosomatids depends on pathways that facilitate the intensive metabolic exchanges between the bacterium and the host protozoan. A search of the annotated symbiont genome database identified one sequence with identity to porin-encoding genes of the genus Bordetella. Considering that the symbiont outer membrane has a great accessibility to cytoplasm host factors, it was important to characterize this single porin-like protein using biochemical, molecular, computational and ultrastructural approaches. Antiserum against the recombinant porin-like molecule revealed that it is mainly located in the symbiont envelope. Secondary structure analysis and comparative modelling predicted the protein 3D structure as an 18-domain β-barrel, which is consistent with porin channels. Electrophysiological measurements showed that the porin displays a slight preference for cations over anions. Taken together, the data presented herein suggest that the C. deanei endosymbiont porin is phylogenetically and structurally similar to those described in Gram-negative bacteria, representing a diffusion channel that might contribute to the exchange of nutrients and metabolic precursors between the symbiont and its host cell.
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Affiliation(s)
- Iamara da Silva Andrade
- Instituto Nacional de Ciência e Tecnologia em Bioimagens e Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil.,Laboratório de Genômica Estrutural, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil.,Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil
| | - João Lídio Vianez-Júnior
- Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil
| | - Carolina Lage Goulart
- Laboratoire de Structure et Fonction des Membranes Biologiques (SFMB), Université Libre de Bruxelles, Campus Plaine (CP 206/2), B-1050 Bruxelles, Belgium.,Unidade Multidisciplinar de Genômica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Bioimagens e Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil
| | - Fabrice Homblé
- Laboratoire de Structure et Fonction des Membranes Biologiques (SFMB), Université Libre de Bruxelles, Campus Plaine (CP 206/2), B-1050 Bruxelles, Belgium
| | - Jean-Marie Ruysschaert
- Laboratoire de Structure et Fonction des Membranes Biologiques (SFMB), Université Libre de Bruxelles, Campus Plaine (CP 206/2), B-1050 Bruxelles, Belgium
| | - Wanda Maria Almeida von Krüger
- Unidade Multidisciplinar de Genômica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Bioimagens e Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil
| | - Paulo Mascarello Bisch
- Unidade Multidisciplinar de Genômica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil.,Laboratório de Física Biológica, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Bioimagens e Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil
| | - Wanderley de Souza
- Instituto Nacional de Metrologia, Normalização e Qualidade Industrial, Inmetro, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Bioimagens e Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil.,Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil
| | - Ronaldo Mohana-Borges
- Instituto Nacional de Ciência e Tecnologia em Bioimagens e Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil.,Laboratório de Genômica Estrutural, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil
| | - Maria Cristina Machado Motta
- Instituto Nacional de Ciência e Tecnologia em Bioimagens e Biologia Estrutural, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, Brazil.,Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-590 Rio de Janeiro, Brazil
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232
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Maris M, Waelkens E, Cnop M, D'Hertog W, Cunha DA, Korf H, Koike T, Overbergh L, Mathieu C. Oleate-induced beta cell dysfunction and apoptosis: a proteomic approach to glucolipotoxicity by an unsaturated fatty acid. J Proteome Res 2011; 10:3372-85. [PMID: 21707097 DOI: 10.1021/pr101290n] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
High levels of fatty acids contribute to loss of functional beta cell mass in type 2 diabetes, in particular in combination with high glucose levels. The aim of this study was to elucidate the role of the unsaturated free fatty acid oleate in glucolipotoxicity and to unravel the molecular pathways involved. INS-1E cells were exposed to 0.5 mM oleate, combined or not with 25 mM glucose, for 24 h. Protein profiling of INS-1E cells was done by 2D-DIGE, covering pH ranges 4-7 and 6-9 (n = 4). Identification of differentially expressed proteins (P < 0.05) was based on MALDI-TOF analysis using Peptide Mass Fingerprint (PMF) and fragmentation (MS/MS) of the most intense peaks of PMF and proteomic results were confirmed by functional assays. Oleate impaired glucose-stimulated insulin secretion and decreased insulin content. 2D-DIGE analysis revealed 53 and 54 differentially expressed proteins for oleate and the combination of oleate and high glucose, respectively. Exposure to oleate down-regulated chaperones, hampered insulin processing and ubiquitin-related proteasomal degradation, and induced perturbations in vesicle transport and budding. In combination with high glucose, shunting of excess amounts of glucose toward reactive oxygen species production worsened beta cell death. The present findings provide new insights in oleate-induced beta cell dysfunction and identify target proteins for preservation of functional beta cell mass in type 2 diabetes.
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Affiliation(s)
- Michael Maris
- Laboratory for Experimental Medicine and Endocrinology (LEGENDO), Herestraat 49, Catholic University of Leuven, Leuven, Belgium
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233
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Gurnev PA, Rostovtseva TK, Bezrukov SM. Tubulin-blocked state of VDAC studied by polymer and ATP partitioning. FEBS Lett 2011; 585:2363-6. [PMID: 21722638 DOI: 10.1016/j.febslet.2011.06.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/08/2011] [Accepted: 06/09/2011] [Indexed: 11/26/2022]
Abstract
Recently reported functional interaction between voltage-dependent anion channel of the outer mitochondrial membrane, VDAC, and dimeric tubulin is observed as a reversible channel blockage. Using partitioning of poly-(ethylene glycol)s of different molecular weights and reversal potential measurements, we probe the size and ion selectivity of the fully open and tubulin-blocked states of VDAC reconstituted into planar lipid bilayers. While the effective radius of the channel decreases by only a factor of 1.34±0.15, the selectivity reverses from initially anionic to cationic. Directly measuring ATP partitioning we demonstrate that these changes prohibit ATP from entering the channel in its tubulin-blocked state.
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Affiliation(s)
- Philip A Gurnev
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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234
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McEwen ML, Sullivan PG, Rabchevsky AG, Springer JE. Targeting mitochondrial function for the treatment of acute spinal cord injury. Neurotherapeutics 2011; 8:168-79. [PMID: 21360236 PMCID: PMC3101832 DOI: 10.1007/s13311-011-0031-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Traumatic injury to the mammalian spinal cord is a highly dynamic process characterized by a complex pattern of pervasive and destructive biochemical and pathophysiological events that limit the potential for functional recovery. Currently, there are no effective therapies for the treatment of spinal cord injury (SCI) and this is due, in part, to the widespread impact of the secondary injury cascades, including edema, ischemia, excitotoxicity, inflammation, oxidative damage, and activation of necrotic and apoptotic cell death signaling events. In addition, many of the signaling pathways associated with these cascades intersect and initiate other secondary injury events. Therefore, it can be argued that therapeutic strategies targeting a specific biochemical cascade may not provide the best approach for promoting functional recovery. A "systems approach" at the subcellular level may provide a better strategy for promoting cell survival and function and, as a consequence, improve functional outcomes following SCI. One such approach is to study the impact of SCI on the biology and function of mitochondria, which serve a major role in cellular bioenergetics, function, and survival. In this review, we will briefly describe the importance and unique properties of mitochondria in the spinal cord, and what is known about the response of mitochondria to SCI. We will also discuss a number of strategies with the potential to promote mitochondrial function following SCI.
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Affiliation(s)
- Melanie L. McEwen
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536–0509 USA
- Department of Physical Medicine and Rehabilitation, University of Kentucky, Lexington, Kentucky 40536–0509 USA
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky 40536–0509 USA
| | - Patrick G. Sullivan
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536–0509 USA
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky 40536–0509 USA
| | - Alexander G. Rabchevsky
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536–0509 USA
- Department of Physiology, University of Kentucky, Lexington, Kentucky 40536–0509 USA
| | - Joe E. Springer
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, KY 40536–0509 USA
- Department of Physical Medicine and Rehabilitation, University of Kentucky, Lexington, Kentucky 40536–0509 USA
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington, Kentucky 40536–0509 USA
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235
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Garcia-Cazarin ML, Gamboa JL, Andrade FH. Rat diaphragm mitochondria have lower intrinsic respiratory rates than mitochondria in limb muscles. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1311-5. [PMID: 21389333 DOI: 10.1152/ajpregu.00203.2010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The mitochondrial content of skeletal muscles is proportional to activity level, with the assumption that intrinsic mitochondrial function is the same in all muscles. This may not hold true for all muscles. For example, the diaphragm is a constantly active muscle; it is possible that its mitochondria are intrinsically different compared with other muscles. This study tested the hypothesis that mitochondrial respiration rates are greater in the diaphragm compared with triceps surae (TS, a limb muscle). We isolated mitochondria from diaphragm and TS of adult male Sprague Dawley rats. Mitochondrial respiration was measured by polarography. The contents of respiratory complexes, uncoupling proteins 1, 2, and 3 (UCP1, UCP2, and UCP3), and voltage-dependent anion channel 1 (VDAC1) were determined by immunoblotting. Complex IV activity was measured by spectrophotometry. Mitochondrial respiration states 3 (substrate and ADP driven) and 5 (uncoupled) were 27 ± 8% and 24 ± 10%, respectively, lower in diaphragm than in TS (P < 0.05 for both comparisons). However, the contents of respiratory complexes III, IV, and V, UCP1, and VDAC1 were higher in diaphragm mitochondria (23 ± 6, 30 ± 8, 25 ± 8, 36 ± 15, and 18 ± 8% respectively, P ≤ 0.04 for all comparisons). Complex IV activity was 64 ± 16% higher in diaphragm mitochondria (P ≤ 0.01). Mitochondrial UCP2 and UCP3 content and complex I activity were not different between TS and diaphragm. These data indicate that diaphragm mitochondria respire at lower rates, despite a higher content of respiratory complexes. The results invalidate our initial hypothesis and indicate that mitochondrial content is not the only determinant of aerobic capacity in the diaphragm. We propose that UCP1 and VDAC1 play a role in regulating diaphragm aerobic capacity.
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236
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Azarashvili TS, Odinokova IV, Krestinina OV, Baburina YL, Grachev DE, Teplova VV, Holmuhamedov EL. Role of phosphorylation of porin (VDAC) in regulation of mitochondrial outer membrane under normal conditions and alcohol intoxication. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2011. [DOI: 10.1134/s1990747811010028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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237
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Yang XY, Chen ZW, Xu T, Qu Z, Pan XD, Qin XH, Ren DT, Liu GQ. Arabidopsis kinesin KP1 specifically interacts with VDAC3, a mitochondrial protein, and regulates respiration during seed germination at low temperature. THE PLANT CELL 2011; 23:1093-106. [PMID: 21406623 PMCID: PMC3082256 DOI: 10.1105/tpc.110.082420] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2010] [Revised: 02/10/2011] [Accepted: 02/21/2011] [Indexed: 05/17/2023]
Abstract
The involvement of cytoskeleton-related proteins in regulating mitochondrial respiration has been revealed in mammalian cells. However, it is unclear if there is a relationship between the microtubule-based motor protein kinesin and mitochondrial respiration. In this research, we demonstrate that a plant-specific kinesin, Kinesin-like protein 1 (KP1; At KIN14 h), is involved in respiratory regulation during seed germination at a low temperature. Using in vitro biochemical methods and in vivo transgenic cell observations, we demonstrate that KP1 is able to localize to mitochondria via its tail domain (C terminus) and specifically interacts with a mitochondrial outer membrane protein, voltage-dependent anion channel 3 (VDAC3). Targeting of the KP1-tail to mitochondria is dependent on the presence of VDAC3. When grown at 4° C, KP1 dominant-negative mutants (TAILOEs) and vdac3 mutants exhibited a higher seed germination frequency. All germinating seeds of the kp1 and vdac3 mutants had increased oxygen consumption; the respiration balance between the cytochrome pathway and the alternative oxidase pathway was disrupted, and the ATP level was reduced. We conclude that the plant-specific kinesin, KP1, specifically interacts with VDAC3 on the mitochondrial outer membrane and that both KP1 and VDAC3 regulate aerobic respiration during seed germination at low temperature.
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238
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Tchakarska G, Roussel M, Troussard X, Sola B. Cyclin D1 inhibits mitochondrial activity in B cells. Cancer Res 2011; 71:1690-9. [PMID: 21343394 DOI: 10.1158/0008-5472.can-10-2564] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cyclin D1 is a cell cycle regulatory protein that acts at the G1-S transition, following its binding to and activation by the cyclin-dependent kinases 4 or 6. Cyclin D1 is absent from the entire B-cell lineage but is present in a large percentage of 2 types of malignant B-cell hemopathy--mantle cell lymphoma and multiple myeloma--suggesting a major role of this protein in the malignancy process. We show here, in an experimental model of cyclin D1 fusion protein transduction in mature B cells, that, cyclin D1 inhibits total mitochondrial activity. Cyclin D1 is localized at the outer mitochondrial membrane, bound to a voltage-dependent anion channel through its central domain, and it competes with hexokinase 2 for binding to this channel. The bound cyclin D1 decreases the supply of ADP, ATP, and metabolites, thereby reducing energy production. This function of cyclin D1 was also reported by others in normal and transformed mammary epithelial cells, suggesting that it may be ubiquitous.
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Affiliation(s)
- Guergana Tchakarska
- Biologie Moléculaire et Cellulaire de la Signalisation, EA 3919, UFR de médecine, IFR 146, Université de Caen, Caen, France
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239
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Liu Y, Yang N, Hao W, Zhao Q, Ying T, Liu S, Li Q, Liang Y, Wang T, Dong Y, Ji C, Zuo P. Dynamic proteomic analysis of protein expression profiles in whole brain of Balb/C mice subjected to unpredictable chronic mild stress: implications for depressive disorders and future therapies. Neurochem Int 2011; 58:904-13. [PMID: 21349309 DOI: 10.1016/j.neuint.2011.02.019] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Revised: 02/11/2011] [Accepted: 02/16/2011] [Indexed: 01/26/2023]
Abstract
The etiology and pathophysiology of depression remain unknown. Previous works were mostly performed on single observation time-point which might be insufficiently to reveal the molecular events changed during the disease development. Adult BALB/c mice were exposed to unpredictable chronic mild stress (UCMS) for different periods and differential 2D gel electrophoresis (DIGE) approach was employed to the brain tissue to explore the molecular disease signatures. Sustained elevation of corticosterone level was observed, suggesting the hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis when the mice were subjected to the stressful situation. The behavioral results indicated the depressive alterations of the mice exposing to UCMS. The altered proteins identified by proteomics showed that abnormal energy mobilization under stress condition was accompanied by overproduction of reactive oxygen species (ROS) and endoplasmic reticulum (ER) stress. Cytoskeleton protein and anti-oxidant enzymes were also changed by UCMS treatment. The results of biochemical and immunohistochemical assay confirmed the changes identified by DIGE analysis. These results indicated that the insufficiency of ATP synthesis, overwhelming ROS production and ER stress subsequently contributed to the cytoskeletal damage and inhibition to expression of some anti-oxidant proteins, which might ultimately bring functional neuron to apoptosis or death. Proteins whose expression is affected may provide tools for potential treatment strategies.
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Affiliation(s)
- Yanyong Liu
- Department of Pharmacology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 5 Dongdansantiao, Beijing 100005, China
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240
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Modulation of plant mitochondrial VDAC by phytosterols. Biophys J 2011; 99:2097-106. [PMID: 20923643 DOI: 10.1016/j.bpj.2010.07.067] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 07/27/2010] [Accepted: 07/28/2010] [Indexed: 12/21/2022] Open
Abstract
We have investigated the effect of cholesterol and two abundant phytosterols (sitosterol and stigmasterol) on the voltage-dependent anion-selective channel (VDAC) purified from mitochondria of bean seeds (Phaseolus coccineus). These sterols differ by the degree of freedom of their lateral chain. We show that VDAC displays sensitivity to the lipid-sterol ratio and to the type of sterol found in the membrane. The main findings of this study are: 1), cholesterol and phytosterols modulate the selectivity but only stigmasterol alters the voltage-dependence of the plant VDAC in the range of sterol fraction found in the plant mitochondrial membrane; 2), VDAC unitary conductance is not affected by the addition of sterols; 3), the effect of sterols on the VDAC is reversible upon sterol depletion with 10 μM methyl-β-cyclodextrins; and 4), phytosterols are essential for the channel gating at salt concentration prevailing in vivo. A quantitative analysis of the voltage-dependence indicates that stigmasterol inhibits the transition of the VDAC in the lowest subconductance states.
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241
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Maldonado EN, Patnaik J, Mullins MR, Lemasters JJ. Free tubulin modulates mitochondrial membrane potential in cancer cells. Cancer Res 2011; 70:10192-201. [PMID: 21159641 DOI: 10.1158/0008-5472.can-10-2429] [Citation(s) in RCA: 168] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Formation of the mitochondrial membrane potential (ΔΨ) depends on flux of respiratory substrates, ATP, ADP, and Pi through voltage-dependent anion channels (VDAC). As tubulin promotes single-channel closure of VDAC, we hypothesized that tubulin is a dynamic regulator of ΔΨ, which in cultured cancer cells was assessed by confocal microscopy of the potential-indicating fluorophore tetramethylrhodamine methylester (TMRM). Microtubule destabilizers, rotenone, colchicine, and nocodazole, and the microtubule stabilizer paclitaxel increased and decreased cellular free tubulin, respectively, and in parallel decreased and increased ΔΨ. Protein kinase A (PKA) activation by cAMP analogues and glycogen synthase kinase 3β (GSK-3β) inhibition decreased ΔΨ, whereas PKA inhibition hyperpolarized, consistent with reports that PKA and GSK-3β decrease and increase VDAC conductance, respectively. Plasma membrane potential assessed by DiBAC(4)(3) was not altered by any of the treatments. We propose that inhibition of VDAC by free tubulin limits mitochondrial metabolism in cancer cells.
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Affiliation(s)
- Eduardo N Maldonado
- Center for Cell Death, Injury & Regeneration, Department of Pharmaceutical & Biomedical Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
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242
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Herrera JL, Diaz M, Hernández-Fernaud JR, Salido E, Alonso R, Fernández C, Morales A, Marin R. Voltage-dependent anion channel as a resident protein of lipid rafts: post-transductional regulation by estrogens and involvement in neuronal preservation against Alzheimer's disease. J Neurochem 2011; 116:820-7. [PMID: 21214547 DOI: 10.1111/j.1471-4159.2010.06987.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The voltage-dependent anion channel, VDAC, is present at the neuronal membrane, where it appears to participate, among others, in the extrinsic apoptotic pathway and in the modulation of amyloid-beta induced injury, suggesting the involvement of this channel in Alzheimer's disease (AD) neurotoxicity. VDAC is also highly concentrated in neuronal lipid raft microdomains of different mouse and human cognitive areas, where it has been shown associated with estrogen receptor alpha (ERα), as a part of a `signalosome' that may activate some intracellular signal transduction. At the plasma membrane level, estrogens and antiestrogens (tamoxifen) have been demonstrated to exert rapid antagonist effects on the activation of VDAC, through their distinct effects on the channel post-transductional modulation. Therefore, part of the alternative mechanisms of estrogen related to neuroprotection against amyloid-beta may involve VDAC phosphorylation, in order to maintain the channel in an unactivated (closing) state. Interestingly, VDAC-ERα association has been shown to be disrupted in neuronal lipid rafts of AD brains, in correlation with the aberrant lipid composition observed in these microstructures, suggesting that disturbance of protein interactions may be related to variation in the physico-chemical properties of these microdomains.
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Affiliation(s)
- Jose Luis Herrera
- Department of Physiology, School of Medicine, La Laguna University, Tenerife, Spain
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243
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Abstract
The voltage-dependent anion channel (VDAC), located in the outer mitochondrial membrane, acts as a gatekeeper for the entry and exit of mitochondrial metabolites. Here we reveal functional dynamics of isoform one of VDAC (VDAC1) by a combination of solution NMR spectroscopy, Gaussian network model analysis, and molecular dynamics simulation. Micro- to millisecond dynamics are significantly increased for the N-terminal six β-strands of VDAC1 in micellar solution, in agreement with increased B-factors observed in the same region in the bicellar crystal structure of VDAC1. Molecular dynamics simulations reveal that a charge on the membrane-facing glutamic acid 73 (E73) accounts for the elevation of N-terminal protein dynamics as well as a thinning of the nearby membrane. Mutation or chemical modification of E73 strongly reduces the micro- to millisecond dynamics in solution. Because E73 is necessary for hexokinase-I-induced VDAC channel closure and inhibition of apoptosis, our results imply that micro- to millisecond dynamics in the N-terminal part of the barrel are essential for VDAC interaction and gating.
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244
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Holmuhamedov EL, Teplova VV, Johnson CB, MacDonald J. A study of the effect of ethanol on the synthesis of serine and the exchange of methyl groups in hepatocytes by NMR spectroscopy. Biophysics (Nagoya-shi) 2010. [DOI: 10.1134/s0006350910060138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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245
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Teplova VV, Belosludtsev KN, Belosludtseva NV, Holmuhamedov EL. Role of mitochondria in hepatotoxicity of ethanol. Biophysics (Nagoya-shi) 2010; 55:951-958. [DOI: 10.1134/s0006350910060114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023] Open
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246
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Retracted article: MAVS protects cells from apoptosis by negatively regulating VDAC1. Mol Cell Biochem 2010; 375:219. [PMID: 21110072 DOI: 10.1007/s11010-010-0658-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 11/15/2010] [Indexed: 11/29/2022]
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247
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Gałgańska H, Antoniewicz M, Budzińska M, Gałgański L, Kmita H. VDAC contributes to mRNA levels in Saccharomyces cerevisiae cells by the intracellular reduction/oxidation state dependent and independent mechanisms. J Bioenerg Biomembr 2010; 42:483-9. [PMID: 21072575 DOI: 10.1007/s10863-010-9315-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2010] [Accepted: 10/19/2010] [Indexed: 02/07/2023]
Abstract
Available data suggest that voltage-dependent anion selective channel (VDAC) constitutes an important component of a cellular regulatory mechanism based on the intracellular reduction/oxidation (redox) state. Here, using quantitative RT-PCR, we demonstrated that depletion of VDAC1 (termed here VDAC) in Saccharomyces cerevisiae cells distinctly affected levels of mRNAs encoding nuclear proteins sensitive to changes of the intracellular redox state including the nuclear transcription factors important for adaptation to the redox state and proteins involved in communication between mitochondria and the nucleus. We also revealed that the changes of the studied protein transcript levels generally correlated with changes of the intracellular redox state although VDAC appears also to affect mRNA levels by a mechanism not based on changes of the intracellular redox states. Thus, VDAC seems to be an important element of the intracellular signaling network.
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Affiliation(s)
- Hanna Gałgańska
- Laboratory of Bioenergetics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614, Poznań, Poland
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248
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Abstract
Mitochondria contain two aqueous compartments: the matrix and the intermembrane space. Whereas many of the biologic functions of the matrix were well characterized in the past, it became clear very recently that the intermembrane space plays a pivotal role in the coordination of mitochondrial activities with other cellular processes. These activities include the exchange of proteins, lipids, or metal ions between the matrix and the cytosol, the regulated initiation of apoptotic cascades, signalling pathways that regulate respiration and metabolic functions, the prevention of reactive oxygen species produced by the respiratory chain, or the control of mitochondrial morphogenesis. We focus on the different biologic functions of the intermembrane space and discuss the relevance of this fascinating compartment for cellular physiology and human health.
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249
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Oligomerization of the mitochondrial protein voltage-dependent anion channel is coupled to the induction of apoptosis. Mol Cell Biol 2010; 30:5698-709. [PMID: 20937774 DOI: 10.1128/mcb.00165-10] [Citation(s) in RCA: 181] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Accumulating evidence implicates that the voltage-dependent anion channel (VDAC) functions in mitochondrion-mediated apoptosis and as a critical player in the release of apoptogenic proteins, such as cytochrome c, triggering caspase activation and apoptosis. The mechanisms regulating cytochrome c release and the molecular architecture of the cytochrome c-conducting channel remain unknown. Here the relationship between VDAC oligomerization and the induction of apoptosis was examined. We demonstrated that apoptosis induction by various stimuli was accompanied by highly increased VDAC oligomerization, as revealed by cross-linking and directly monitored in living cells using bioluminescence resonance energy transfer technology. VDAC oligomerization was induced in all cell types and with all apoptosis inducers used, including staurosporine, curcumin, As(2)O(3), etoposide, cisplatin, selenite, tumor necrosis factor alpha (TNF-α), H(2)O(2), and UV irradiation, all acting through different mechanisms yet all involving mitochondria. Moreover, correlation between the levels of VDAC oligomerization and apoptosis was observed. Furthermore, the apoptosis inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) inhibited VDAC oligomerization. Finally, a caspase inhibitor had no effect on VDAC oligomerization and cytochrome c release. We propose that VDAC oligomerization is involved in mitochondrion-mediated apoptosis and may represent a general mechanism common to numerous apoptogens acting via different initiating cascades. Thus, targeting the oligomeric status of VDAC, and hence apoptosis, offers a therapeutic strategy for combating cancers and neurodegenerative diseases.
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250
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Imada S, Yamamoto M, Tanaka K, Seiwa C, Watanabe K, Kamei Y, Kozuma S, Taketani Y, Asou H. Hypothermia-induced increase of oligodendrocyte precursor cells: Possible involvement of plasmalemmal voltage-dependent anion channel 1. J Neurosci Res 2010; 88:3457-66. [PMID: 20936704 DOI: 10.1002/jnr.22520] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Revised: 08/17/2010] [Accepted: 08/26/2010] [Indexed: 12/20/2022]
Abstract
Hypothermia is believed to suppress cell proliferation by inducing apoptosis/necrosis and phase-specific/nonspecific cell cycle arrest, which are, directly or indirectly, related to a reduced energy supply. Intriguingly, hypothermia is known to improve neurological recovery of animals and humans exposed to focal brain hypoxic-ischemic injury. The underlying mechanism of the neuroprotective effect of hypothermia is unclear, although the prevention of neural cell apoptosis is thought to play a role. Herein we demonstrate that in vitro cell culture of oligodendrocyte precursor cells (OPCs) under conditions of mild hypothermia (31.5°C) results in an increase in cell number relative to cells cultured under normothermic conditions (37°C). Cell cycle analysis, immunoblotting of cyclins, TUNEL assay, and immunocytochemistry of OPC differentiation markers suggest that hypothermia shifts the balance between proliferation and apoptosis/differentiation toward proliferation. A combination of transcriptome analysis, pharmacological intervention, and immunoaffinity-based assays suggests a possible involvement of the Gα13-Rho GTPase Cdc42-ERK1/2 signaling cascade and voltage-dependent anion channel 1 (VDAC1), which associate or dissociate with Gα13 protein at 37°C and 31.5°C, respectively. Immunoelectron microscopy revealed the presence of VDAC1 in the plasma membrane of OPCs. Furthermore, the exogenous addition of impermeable VDAC1 inhibitors enhanced proliferation of OPCs at 37°C. These results may contribute to the elucidation of the mechanism of hypothermic neuroprotection as well as the possible novel role of plasmalemmal VDAC1.
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Affiliation(s)
- Shinya Imada
- Department of Neuro-Glia Cell Biology, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
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