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Bcl-2 family in inter-organelle modulation of calcium signaling; roles in bioenergetics and cell survival. J Bioenerg Biomembr 2014; 46:1-15. [PMID: 24078116 DOI: 10.1007/s10863-013-9527-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 08/27/2013] [Indexed: 01/01/2023]
Abstract
Bcl-2 family proteins, known for their apoptosis functioning at the mitochondria, have been shown to localize to other cellular compartments to mediate calcium (Ca2+) signals. Since the proper supply of Ca2+ in cells serves as an important mechanism for cellular survival and bioenergetics, we propose an integrating role for Bcl-2 family proteins in modulating Ca2+ signaling. The endoplasmic reticulum (ER) is the main Ca2+ storage for the cell and Bcl-2 family proteins competitively regulate its Ca2+ concentration. Bcl-2 family proteins also regulate the flux of Ca2+ from the ER by physically interacting with inositol 1,4,5-trisphosphate receptors (IP3Rs) to mediate their opening. Type 1 IP3Rs reside at the bulk ER to coordinate cytosolic Ca2+ signals, while type 3 IP3Rs reside at mitochondria-associated ER membrane (MAM) to facilitate mitochondrial Ca2+ uptake. In healthy cells, mitochondrial Ca2+ drives pyruvate into the citric acid (TCA) cycle to facilitate ATP production, while a continuous accumulation of Ca2+ can trigger the release of cytochrome c, thus initiating apoptosis. Since multiple organelles and Bcl-2 family proteins are involved in Ca2+ signaling, we aim to clarify the role that Bcl-2 family proteins play in facilitating Ca2+ signaling and how mitochondrial Ca2+ is relevant in both bioenergetics and apoptosis. We also explore how these insights could be useful in controlling bioenergetics in apoptosis-resistant cell lines.
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Martel C, Wang Z, Brenner C. VDAC phosphorylation, a lipid sensor influencing the cell fate. Mitochondrion 2014; 19 Pt A:69-77. [DOI: 10.1016/j.mito.2014.07.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 07/17/2014] [Accepted: 07/22/2014] [Indexed: 12/21/2022]
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An B, Chen Y, Li B, Qin G, Tian S. Ca(2+)-CaM regulating viability of Candida guilliermondii under oxidative stress by acting on detergent resistant membrane proteins. J Proteomics 2014; 109:38-49. [PMID: 24998432 DOI: 10.1016/j.jprot.2014.06.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 06/10/2014] [Accepted: 06/26/2014] [Indexed: 11/18/2022]
Abstract
UNLABELLED Reactive oxygen species (ROS) play a vital role in reducing viability of yeast cells. The Ca(2+)-CaM signaling pathways are involved in regulating the intracellular ROS level in yeast cells under stress. Detergent resistant membranes (DRMs), the sterol-rich microdomains, participate in a wide range of cellular processes including growth, trafficking and death in yeast cells. In the present study, we found that Trifluoperazine (TFP), an antagonist of CaM, could increase the viability of Candida guilliermondii cells under H2O2 stress. Based on comparative analysis of DRM sub proteomics, a total number of 29 differentially expressed protein spots were identified, among which 8 protein spots belong to the electron transport chain and 7 protein spots belong to transporters. It is suggested that TFP treatment could modulate the intracellular ROS generation in yeast cells. We additionally ascertained that TFP treatment could effectively alleviate the ROS accumulation and protein damage in C. guilliermondii cells under H2O2 stress, via investigating the intracellular ROS levels and protein oxidative damage in yeast cells. These findings firstly revealed that the Ca(2+)-CaM signaling pathway is related to the viability of yeast cells under H2O2 stress, and provide novel evidences for exploring Ca(2+)-CaM's role in regulating this viability via acting on DRM proteins. BIOLOGICAL SIGNIFICANCE Detergent-resistant membranes (DRMs), which are more resistant to extraction with cold non-ionic detergents, have been considered the functional microdomains in the plasma membrane. In yeast, DRMs are involved in a wide range of additional cellular processes including cell growth and death. The Ca(2+)-CaM signaling pathways could regulate the stress tolerance of yeast cells by modulating the intracellular ROS generation. In this study, we found that trifluoperazine (TFP), a calmodulin antagonist, could increase the viability of C. guilliermondii under H2O2 stress. Based on comparative analysis of DRM sub proteomics, electron transport chain proteins and transporters were identified to be associated with the Ca(2+)-CaM transduction. We proved that TFP treatment decreases the intracellular ROS accumulation and alleviates oxidative damage to cellular proteins. These results ascertain that Ca(2+)-CaM is involved in regulating the viability of C. guilliermondii under oxidative stress via acting on the DRM proteins.
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Affiliation(s)
- Bang An
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yong Chen
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Boqiang Li
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Guozheng Qin
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Shiping Tian
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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Abstract
The field of mitochondrial ion channels has recently seen substantial progress, including the molecular identification of some of the channels. An integrative approach using genetics, electrophysiology, pharmacology, and cell biology to clarify the roles of these channels has thus become possible. It is by now clear that many of these channels are important for energy supply by the mitochondria and have a major impact on the fate of the entire cell as well. The purpose of this review is to provide an up-to-date overview of the electrophysiological properties, molecular identity, and pathophysiological functions of the mitochondrial ion channels studied so far and to highlight possible therapeutic perspectives based on current information.
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Mitochondrial ion channels as oncological targets. Oncogene 2014; 33:5569-81. [DOI: 10.1038/onc.2013.578] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 12/04/2013] [Accepted: 12/05/2013] [Indexed: 02/06/2023]
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Zhang L, Wang S, Dong H, Li Y, Wang P, Li S, Guo Y, Yao R. Spermine attenuates the preconditioning of diazoxide against transient focal cerebral ischemia in rats. Neurol Res 2013; 36:666-72. [PMID: 24620960 DOI: 10.1179/1743132813y.0000000299] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
It is known that mitochondrial ATP-sensitive potassium channels (mitoKATP) play a significant role in protecting cerebral function from ischemia-reperfusion injury, which is related with a decrease in the mitochondrial matrix calcium. However, the effect of mitochondrial calcium uniporter (MCU) on diazoxide-induced cerebral protection is still indistinct. The purpose of the present paper is to further observe the relationship between mitoKATP and MCU, and to probe the mechanism. Adult male Wistar rats were randomly divided into five groups: the Sham group, the I-R group, the Dzx+I-R group, the Dzx+Sper+I-R group, and the Sper+I-R group. Rats not in the Sham group were exposed to 2-hour ischemia followed by 24-hour reperfusion. Diazoxide and spermine were administrated 30 minutes before ischemia or 10 minutes before reperfusion, respectively. After 24-hour reperfusion, animals were given neurological performance tests, overdosed with general anesthesia, and then their brains were excised for infarct volume, pathological changes, and apoptosis analysis. The beneficial effects of diazoxide (improved neurological deficits, decreased infarct volume, and apoptosis, evidenced by the decreased expression of cytochrome c and Bax) were significantly neutralized by spermine. The results of the present work suggest that diazoxide-induced cerebral protection against ischemia-reperfusion injury is mediated by spermine through apoptotic pathway.
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Leanza L, Biasutto L, Managò A, Gulbins E, Zoratti M, Szabò I. Intracellular ion channels and cancer. Front Physiol 2013; 4:227. [PMID: 24027528 PMCID: PMC3759743 DOI: 10.3389/fphys.2013.00227] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 08/05/2013] [Indexed: 02/02/2023] Open
Abstract
Several types of channels play a role in the maintenance of ion homeostasis in subcellular organelles including endoplasmatic reticulum, nucleus, lysosome, endosome, and mitochondria. Here we give a brief overview of the contribution of various mitochondrial and other organellar channels to cancer cell proliferation or death. Much attention is focused on channels involved in intracellular calcium signaling and on ion fluxes in the ATP-producing organelle mitochondria. Mitochondrial K+ channels (Ca2+-dependent BKCa and IKCa, ATP-dependent KATP, Kv1.3, two-pore TWIK-related Acid-Sensitive K+ channel-3 (TASK-3)), Ca2+ uniporter MCU, Mg2+-permeable Mrs2, anion channels (voltage-dependent chloride channel VDAC, intracellular chloride channel CLIC) and the Permeability Transition Pore (MPTP) contribute importantly to the regulation of function in this organelle. Since mitochondria play a central role in apoptosis, modulation of their ion channels by pharmacological means may lead to death of cancer cells. The nuclear potassium channel Kv10.1 and the nuclear chloride channel CLIC4 as well as the endoplasmatic reticulum (ER)-located inositol 1,4,5-trisphosphate (IP3) receptor, the ER-located Ca2+ depletion sensor STIM1 (stromal interaction molecule 1), a component of the store-operated Ca2+ channel and the ER-resident TRPM8 are also mentioned. Furthermore, pharmacological tools affecting organellar channels and modulating cancer cell survival are discussed. The channels described in this review are summarized on Figure 1. Overall, the view is emerging that intracellular ion channels may represent a promising target for cancer treatment.
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Affiliation(s)
- Luigi Leanza
- Department of Biology, University of Padova Padova, Italy
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58
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Bax induces cytochrome c release by multiple mechanisms in mitochondria from MCF7 cells. J Bioenerg Biomembr 2013; 45:441-8. [PMID: 23536162 DOI: 10.1007/s10863-013-9508-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/14/2013] [Indexed: 10/27/2022]
Abstract
Bax, a pro-apoptotic member of the Bcl-2 family of proteins has the ability to form transmembrane pores large enough to allow cytochrome c (Cyt c) release, as well as to activate the mitochondrial permeability transition pore (mPTP); however, no differential study has been conducted to clarify which one of these mechanisms predominates over the other in the same system. In the present study, we treated isolated mitochondria from MCF7 cells with recombinant protein Bax and tested the efficacy of the mPTP inhibitor cyclosporin A (CsA) and of the Bax channel blocker (Bcb) to inhibit cytochrome c release. We also, induced apoptosis in MCF7 cell cultures with TNF-α plus cycloheximide to determine the effect of such compounds in apoptosis induction via mPTP or Bax oligomerization. Cytochrome c release was totally prevented by CsA and partially by Bcb when apoptosis was induced with recombinant Bax in isolated mitochondria from MCF7 cells. CsA increased the number of living cells in cell culture, as compared with the effect of Bax channel blocker. These results indicate that mPTP activation is the predominant pathway for Bax-induced cytochrome c release from MCF7 mitochondria and for apoptosis induction in the whole cell.
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Suh DH, Kim MK, Kim HS, Chung HH, Song YS. Mitochondrial permeability transition pore as a selective target for anti-cancer therapy. Front Oncol 2013; 3:41. [PMID: 23483560 PMCID: PMC3592197 DOI: 10.3389/fonc.2013.00041] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 02/12/2013] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial outer membrane permeabilization (MOMP) is the ultimate step in dozens of lethal apoptotic signal transduction pathways which converge on mitochondria. One of the representative systems proposed to be responsible for the MOMP is the mitochondrial permeability transition pore (MPTP). Although the molecular composition of the MPTP is not clearly understood, the MPTP attracts much interest as a promising target for resolving two conundrums regarding cancer treatment: tumor selectivity and resistance to treatment. The regulation of the MPTP is closely related to metabolic reprogramming in cancer cells including mitochondrial alterations. Restoration of deregulated apoptotic machinery in cancer cells by tumor-specific modulation of the MPTP could therefore be a promising anti-cancer strategy. Currently, a number of MPTP-targeting agents are under pre-clinical and clinical studies. Here, we reviewed the structure and regulation of the MPTP as well as the current status of the development of promising MPTP-targeting drugs.
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Affiliation(s)
- Dong H Suh
- Department of Obstetrics and Gynecology, Seoul National University College of Medicine Seoul, South Korea
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60
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Zhang W, Feng H, Gao Y, Sun L, Wang J, Li Y, Wang C, Zhao L, Hu X, Sun H, Wei Y, Sun D. Role of pigment epithelium-derived factor (PEDF) in arsenic-induced cell apoptosis of liver and brain in a rat model. Biol Trace Elem Res 2013; 151:269-76. [PMID: 23229538 DOI: 10.1007/s12011-012-9558-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 11/20/2012] [Indexed: 11/26/2022]
Abstract
Although studies have shown that arsenic exposure can induce apoptosis in a variety of cells, the exact molecular mechanism of chronic arsenicosis remains unclear. Based on our previous study on human serum, the present study was to determine whether pigment epithelium-derived factor (PEDF) plays a role in the damage induced by chronic arsenic exposure in a rat model and to explore the possible signaling pathway involved. Thirty male Wistar rats were randomly divided into three groups and the arsenite doses administered were 0, 10, and 50 mg/L, respectively. The experiment lasted for 6 months. Our results showed that level of arsenic increased significantly in serum, liver, brain, and kidney in arsenic-exposed groups. It was indicated that PEDF protein was widely distributed in the cytoplasm of various types of cells in liver, brain, and kidney. PEDF protein level was only changed when the arsenite dose reached 50 mg/L in liver and brain, whereas it was not changed in the kidney. In order to investigate the possible mechanism of PEDF-exerted damages upon arsenite exposure, apoptosis in liver and brain was assessed. The proportion of apoptotic cells gradually increased with increasing arsenic administration. The ratio of Bax/Bcl-2 in the high arsenic group (50 mg/L) was significantly higher than that in the control group. Therefore, we thought PEDF played a role in cell apoptosis of liver and brain which induced by sodium arsenite exposure, and the results also demonstrated that Bax and Bcl-2 might be two key targets in the action of PEDF.
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Affiliation(s)
- Wei Zhang
- Center for Endemic Disease Control, Chinese Center for Disease Control and Prevention, Harbin Medical University, Harbin, China
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61
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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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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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63
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Zhang X, Weng C, Li Y, Wang X, Jiang C, Li X, Xu Y, Chen Q, Pan L, Tang H. Human Bop is a novel BH3-only member of the Bcl-2 protein family. Protein Cell 2012; 3:790-801. [PMID: 23055042 DOI: 10.1007/s13238-012-2069-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 08/17/2012] [Indexed: 12/12/2022] Open
Abstract
One group of Bcl-2 protein family, which shares only the BH3 domain (BH3-only), is critically involved in the regulation of programmed cell death. Herein we demonstrated a novel human BH3-only protein (designated as Bop) which could induce apoptosis in a BH3 domain-dependent manner. Further analysis indicated that Bop mainly localized to mitochondria and used its BH3 domain to contact the loop regions of voltage dependent anion channel 1 (VDAC1) in the outer mitochondrial membrane. In addition, purified Bop protein induced the loss of mitochondrial transmembrane potential (Δψm) and the release of cytochrome c. Furthermore, Bop used its BH3 domain to contact pro-survival Bcl-2 family members (Bcl-2, Bcl-X(L), Mcl-1, A1 and Bcl-w), which could inhibit Bop-induced apoptosis. Bop would be constrained by pro-survival Bcl-2 proteins in resting cells, because Bop became released from phosphorylated Bcl-2 induced by microtubule-interfering agent like vincristine (VCR). Indeed, knockdown experiments indicated that Bop was partially required for VCR induced cell death. Finally, Bop might need to function through Bak and Bax, likely by releasing Bak from Bcl-X(L) sequestration. In conclusion, Bop may be a novel BH3-only factor that can engage with the regulatory network of Bcl-2 family members to process intrinsic apoptotic signaling.
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Affiliation(s)
- Xiaoping Zhang
- The Key Laboratory of Infection and Immunology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
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64
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Lee WK, Bork U, Thévenod F. Mitochondria as a target of cadmium nephrotoxicity: induction of swelling and cytochrome C release. Toxicol Mech Methods 2012; 14:67-71. [PMID: 20021126 DOI: 10.1080/15376520490257509] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cadmium (Cd) is a potent environmental toxic compound that damages the kidney by inducing apoptosis of the proximal tubule cells. The mitochondrion is a pivotal point of the apoptotic pathway because it releases pro-apoptotic factors such as cytochrome c. Using mitochondria isolated by differential centrifugation from rat kidney cortex, we monitored swelling, which is thought to reflect the opening of a mitochondrial permeability transition pore and mitochondrial dysfunction. At Cd concentrations of 5 muM or more, rapid swelling occurred. Moreover, Cd had concentration-dependent effects on swelling induced by the permeability transition pore opener PO(4)(3-): At concentrations of 5 muM or less, PO(4)(3-)-induced swelling was enhanced and cytochrome c release was increased, whereas more than 5 muM Cd significantly inhibited both PO(4)(3-)-induced swelling and cytochrome c release. Thus, Cd may directly interfere with normal mitochondrial function and may also trigger pro-apoptotic pathways in proximal tubule cells in the kidney.
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Affiliation(s)
- Wing-Kee Lee
- Department of Physiology and Pathophysiology, University of Witten/Herdecke, Witten, Germany
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65
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Chen C, Chen C, Wang Z, Wang L, Yang L, Ding M, Ding C, Sun Y, Lin Q, Huang X, Du X, Zhao X, Wang C. Puerarin induces mitochondria-dependent apoptosis in hypoxic human pulmonary arterial smooth muscle cells. PLoS One 2012; 7:e34181. [PMID: 22457823 PMCID: PMC3311615 DOI: 10.1371/journal.pone.0034181] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 02/28/2012] [Indexed: 02/03/2023] Open
Abstract
Background Pulmonary vascular medial hypertrophy in hypoxic pulmonary arterial hypertension (PAH) is caused in part by decreased apoptosis in pulmonary artery smooth muscle cells (PASMCs). Puerarin, an isoflavone purified from the Chinese medicinal herb kudzu, ameliorates chronic hypoxic PAH in animal models. Here we investigated the effects of puerarin on apoptosis of hypoxic human PASMCs (HPASMCs), and to determine the possible underlying mechanisms. Methodology/Principal Findings HPASMCs were cultured for 24 h in normoxia or hypoxia (5% O2) conditions with and without puerarin. Cell number and viability were determined with a hemacytometer or a cell counting kit. Apoptosis was detected with a TUNEL test, rhodamine-123 (R-123) fluorescence, a colorimetric assay, western blots, immunohistochemical staining and RT-PCR. Hypoxia inhibited mitochondria-dependent apoptosis and promoted HPASMC growth. In contrast, after puerarin (50 µM or more) intervention, cell growth was inhibited and apoptosis was observed. Puerarin-induced apoptosis in hypoxic HPASMCs was accompanied by reduced mitochondrial membrane potential, cytochrome c release from the mitochondria, caspase-9 activation, and Bcl-2 down-regulation with concurrent Bax up-regulation. Conclusions/Significance Puerarin promoted apoptosis in hypoxic HPASMCs by acting on the mitochondria-dependent pathway. These results suggest a new mechanism of puerarin relevant to the management of clinical hypoxic pulmonary hypertension.
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Affiliation(s)
- Chan Chen
- Department of Geriatric Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Chun Chen
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Zhiyi Wang
- Department of Emergency Medicine, The Second Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Liangxing Wang
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
- * E-mail:
| | - Lehe Yang
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Minjiao Ding
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Cheng Ding
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Yu Sun
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Quan Lin
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Xiaoying Huang
- Department of Respiratory Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Xiaohong Du
- Department of Geriatric Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Xiaowei Zhao
- Department of Geriatric Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Chuangyi Wang
- Department of Geriatric Medicine, The First Affiliated Hospital of Wenzhou Medical College, Wenzhou, Zhejiang, China
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Sharaf el dein O, Gallerne C, Brenner C, Lemaire C. Increased expression of VDAC1 sensitizes carcinoma cells to apoptosis induced by DNA cross-linking agents. Biochem Pharmacol 2012; 83:1172-82. [PMID: 22285227 DOI: 10.1016/j.bcp.2012.01.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 01/12/2012] [Accepted: 01/13/2012] [Indexed: 11/30/2022]
Abstract
A major clinical problem regarding antitumoral treatment with DNA cross-linking agents such as cisplatin (Cisp), mechlorethamine (HN2) or its derivative melphalan (MLP) is intrinsic or acquired resistance to therapy, which frequently results from a resistance to apoptosis induction. In this study, aimed to identify novel sensitizing targets to DNA cross-linker-induced cell death, we demonstrated that MLP, Cisp and HN2 induce mitochondrial permeability transition pore (PTP)-mediated apoptosis in cervical and colon carcinoma cells. This apoptotic pathway is characterized by dissipation of the mitochondrial membrane potential, production of ROS, mitochondrial translocation of Bax, release of apoptogenic factors, caspase activation and nuclear alterations. The opening of PTP and subsequent apoptosis was reduced in Bax deficient cells and in cells with elevated Bcl-2 level, but not in cells invalidated for Bak. We further showed that, among the pro-apoptotic PTP regulators tested (VDAC1, creatine kinase, ANT1 and ANT3), exogenous overexpression of VDAC1 was the most effective in enhancing Cisp- and MLP-induced apoptosis. In addition, pharmacologically induced up-regulation of VDAC1 by the chemotherapeutic agent arsenic trioxide (As(2)O(3)) greatly sensitized HeLa cells to Cisp and MLP treatment. These data indicate that increased expression of VDAC1 appears as a promising strategy to improve DNA cross-linker-induced chemotherapy.
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Affiliation(s)
- Ossama Sharaf el dein
- INSERM UMR-S 769, LabEx LERMIT, Université Paris-Sud 11, 5 rue J B Clement, Chatenay-Malabry, France.
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67
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Biology of mitochondria in neurodegenerative diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 107:355-415. [PMID: 22482456 DOI: 10.1016/b978-0-12-385883-2.00005-9] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal degeneration in these familial diseases, and in the more common idiopathic (sporadic) diseases, are unresolved. Genetic, biochemical, and morphological analyses of human AD, PD, and ALS, as well as their cell and animal models, reveal that mitochondria could have roles in this neurodegeneration. The varied functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and the overlying genetic variations. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial programmed cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This chapter reviews several aspects of mitochondrial biology and how mitochondrial pathobiology might contribute to the mechanisms of neurodegeneration in AD, PD, and ALS.
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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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Wang Y, Pan Y, Price A, Martin LJ. Generation and characterization of transgenic mice expressing mitochondrial targeted red fluorescent protein selectively in neurons: modeling mitochondriopathy in excitotoxicity and amyotrophic lateral sclerosis. Mol Neurodegener 2011; 6:75. [PMID: 22047141 PMCID: PMC3227596 DOI: 10.1186/1750-1326-6-75] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Accepted: 11/02/2011] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Mitochondria have roles or appear to have roles in the pathogenesis of several chronic age-related and acute neurological disorders, including Charcot-Marie-Tooth disease, amyotrophic lateral sclerosis, Parkinson's disease, and cerebral ischemia, and could be critical targets for development of rational mechanism-based, disease-modifying therapeutics for treating these disorders effectively. A deeper understanding of neural tissue mitochondria pathobiologies as definitive mediators of neural injury, disease, and cell death merits further study, and the development of additional tools to study neural mitochondria will help achieve this unmet need. RESULTS We created transgenic mice that express the coral (Discosoma sp.) red fluorescent protein DsRed2 specifically in mitochondria of neurons using a construct engineered with a Thy1 promoter, specific for neuron expression, to drive expression of a fusion protein of DsRed2 with a mitochondrial targeting sequence. The biochemical and histological characterization of these mice shows the expression of mitochondrial-targeted DsRed2 to be specific for mitochondria and concentrated in distinct CNS regions, including cerebral cortex, hippocampus, thalamus, brainstem, and spinal cord. Red fluorescent mitochondria were visualized in cerebral cortical and hippocampal pyramidal neurons, ventrobasal thalamic neurons, subthalamic neurons, and spinal motor neurons. For the purpose of proof of principle application, these mice were used in excitotoxicity paradigms and double transgenic mice were generated by crossing Thy1-mitoDsRed2 mice with transgenic mice expressing enhanced-GFP (eGFP) under the control of the Hlxb9 promoter that drives eGFP expression specifically in motor neurons and by crossing Thy1-mitoDsRed2 mice to amyotrophic lateral sclerosis (ALS) mice expressing human mutant superoxide dismutase-1. CONCLUSIONS These novel transgenic mice will be a useful tool for better understanding the biology of mitochondria in mouse and cellular models of human neurological disorders as exemplified by the mitochondrial swelling and fission seen in excitotoxicity and mouse ALS.
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Affiliation(s)
- Yi Wang
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, MD 21205, USA
| | - Yan Pan
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, MD 21205, USA
| | - Ann Price
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, MD 21205, USA
| | - Lee J Martin
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, MD 21205, USA
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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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71
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Ulukaya E, Acilan C, Yilmaz Y. Apoptosis: why and how does it occur in biology? Cell Biochem Funct 2011; 29:468-80. [PMID: 21773978 DOI: 10.1002/cbf.1774] [Citation(s) in RCA: 160] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2010] [Revised: 03/30/2011] [Accepted: 05/17/2011] [Indexed: 01/24/2023]
Abstract
The literature on apoptosis has grown tremendously in recent years, and the mechanisms that are involved in this programmed cell death pathway have been enlightened. It is now known that apoptosis takes place starting from early development to adult stage for the homeostasis of multicellular organisms, during disease development and in response to different stimuli in many different systems. In this review, we attempted to summarize the current knowledge on the circumstances and the mechanisms that lead to induction of apoptosis, while going over the molecular details of the modulator and mediators of apoptosis as well as drawing the lines between programmed and non-programmed cell death pathways. The review will particularly focus on Bcl-2 family proteins, the role of different caspases in the process of apoptosis, and their inhibitors as well as the importance of apoptosis during different disease states. Understanding the molecular mechanisms involved in apoptosis better will make a big impact on human diseases, particularly cancer, and its management in the clinics.
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Affiliation(s)
- Engin Ulukaya
- Medical School of Uludag University, Medical Biochemistry Department, Bursa, Turkey.
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72
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XU LH, CHANG YM, LIU CL, LIANG LQ, LIU JL, CHI BJ. Screening cold-acclimation differential expression candidate genes in the brain of common carp ( Cyprinus carpio). YI CHUAN = HEREDITAS 2011; 33:262-9. [DOI: 10.3724/sp.j.1005.2011.00262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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73
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Sanbe A, Marunouchi T, Yamauchi J, Tanonaka K, Nishigori H, Tanoue A. Cardioprotective effect of nicorandil, a mitochondrial ATP-sensitive potassium channel opener, prolongs survival in HSPB5 R120G transgenic mice. PLoS One 2011; 6:e18922. [PMID: 21541347 PMCID: PMC3081834 DOI: 10.1371/journal.pone.0018922] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 03/17/2011] [Indexed: 11/29/2022] Open
Abstract
Background Transgenic (TG) mice with overexpression of an arg120gly (R120G) missense mutation in HSPB5 display desmin-related cardiomyopathy, which is characterized by formation of aggresomes. It is also known that progressive mitochondrial abnormalities and apoptotic cell death occur in the hearts of R120G TG mice. The role of mitochondrial dysfunction and apoptosis in disease progression, however, remains uncertain. Methods and Results Mitochondrial abnormalities and apoptotic cell death induced by overexpression of HSPB5 R120G were analyzed in neonatal rat cardiomyocytes. Overexpression of mutant HSPB5 led to development of aggresomes with a concomitant reduction in cell viability in the myocytes. Overexpression of mutant HSPB5 induced a reduction in the cytochrome c level in the mitochondrial fraction and a corresponding increase in the cytoplasmic fraction in the myocytes. Down-regulation of BCL2 and up-regulation of BAX were detected in the myocytes expressing the mutant HSPB5. Concomitant with mitochondrial abnormality, the activation of caspase-3 and increased apoptotic cell death was observed. Cell viability was dose-dependently recovered in myocytes overexpressing HSPB5 R120G by treatment with nicorandil a mitochondrial ATP-sensitive potassium channel opener. Nicorandil treatment also inhibited the increase in BAX, the decrease in BCL2, activation of caspase-3 and apoptotic cell death by mutant HSPB5. To confirm the results of the in-vitro study, we analyzed the effect of nicorandil in HSPB5 R120G TG mice. Nicorandil treatment appeared to reduce mitochondrial impairment and apoptotic cell death and prolonged survival in HSPB5 R120G TG mice. Conclusions Nicorandil may prolong survival in HSPB5 R120G TG mice by protecting against mitochondrial impairments.
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Affiliation(s)
- Atsushi Sanbe
- Department of Pharmacotherapeutics, School of Pharmacy, Iwate Medical University, Iwate, Japan.
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Ichimura T, Ito M, Takahashi K, Oyama K, Sakurai K. Involvement of mitochondrial swelling in cytochrome c release from mitochondria treated with calcium and Alloxan. ACTA ACUST UNITED AC 2011. [DOI: 10.4236/jbpc.2011.21002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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75
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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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76
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Dominant-negative VDAC1 mutants reveal oligomeric VDAC1 to be the active unit in mitochondria-mediated apoptosis. Biochem J 2010; 429:147-55. [DOI: 10.1042/bj20091338] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Mitochondria play a central role in the intrinsic pathway of apoptosis. Oligomerization of the mitochondrial protein VDAC1 (voltage-dependent anion channel 1) has been proposed to play a role in apoptosis in various studies. In the present study, we have generated dimeric fusion proteins consisting of tandem-linked wild-type and RuR (Ruthenium Red)-insensitive mutant VDAC1 monomers and studied the capacity of RuR to protect against apoptosis, as induced by various means. Fusion proteins composed of wild-type and/or E72Q-VDAC1 were successfully expressed in T-REx-293 cells. Bilayer-reconstituted dimeric rVDAC1 (rat VDAC1) functions as a channel-forming protein, showing typical voltage-dependence conductance, but with a unitary conductance higher than that of monomeric VDAC. As with wild-type VDAC1, overexpression of either the wild-type or mutated VDAC1 dimeric fusion protein induced apoptotic cell death. In addition, as shown previously, the anti-apoptotic effect of RuR was not observed in cells expressing E72Q-VDAC1, despite endogenous VDAC1 being present in these cells. Similar RuR insensitivity governed the VDAC1 fusion proteins comprising the E72Q mutation in either the first, second or both VDAC1 monomers of the same dimer. RuR-mediated protection against apoptosis in T-REx-293 cells, as induced by staurosporine, was observed in cells expressing VDAC1 or dimeric wild-type VDAC1. However, RuR offered no protection against staurosporine-induced apoptosis in cells expressing E72Q-VDAC1 or E72Q-containing dimeric VDAC1. These results suggest that E72Q-VDAC1 has a dominant-negative effect and implies that VDAC1 homo-oligomerization, involving intermolecular interactions, might be involved in the apoptotic process.
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77
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Krampe B, Al-Rubeai M. Cell death in mammalian cell culture: molecular mechanisms and cell line engineering strategies. Cytotechnology 2010; 62:175-88. [PMID: 20502964 DOI: 10.1007/s10616-010-9274-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Accepted: 04/12/2010] [Indexed: 12/15/2022] Open
Abstract
Cell death is a fundamentally important problem in cell lines used by the biopharmaceutical industry. Environmental stress, which can result from nutrient depletion, by-product accumulation and chemical agents, activates through signalling cascades regulators that promote death. The best known key regulators of death process are the Bcl-2 family proteins which constitute a critical intracellular checkpoint of apoptosis cell death within a common death pathway. Engineering of several members of the anti-apoptosis Bcl-2 family genes in several cell types has extended the knowledge of their molecular function and interaction with other proteins, and their regulation of cell death. In this review, we describe the various modes of cell death and their death pathways at molecular and organelle level and discuss the relevance of the growing knowledge of anti-apoptotic engineering strategies to inhibit cell death and increase productivity in mammalian cell culture.
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Affiliation(s)
- Britta Krampe
- School of Chemical and Bioprocess Engineering, and Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Republic of Ireland
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Abstract
Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS) are the most common human adult-onset neurodegenerative diseases. They are characterized by prominent age-related neurodegeneration in selectively vulnerable neural systems. Some forms of AD, PD, and ALS are inherited, and genes causing these diseases have been identified. Nevertheless, the mechanisms of the neuronal cell death are unresolved. Morphological, biochemical, genetic, as well as cell and animal model studies reveal that mitochondria could have roles in this neurodegeneration. The functions and properties of mitochondria might render subsets of selectively vulnerable neurons intrinsically susceptible to cellular aging and stress and overlying genetic variations, triggering neurodegeneration according to a cell death matrix theory. In AD, alterations in enzymes involved in oxidative phosphorylation, oxidative damage, and mitochondrial binding of Aβ and amyloid precursor protein have been reported. In PD, mutations in putative mitochondrial proteins have been identified and mitochondrial DNA mutations have been found in neurons in the substantia nigra. In ALS, changes occur in mitochondrial respiratory chain enzymes and mitochondrial cell death proteins. Transgenic mouse models of human neurodegenerative disease are beginning to reveal possible principles governing the biology of selective neuronal vulnerability that implicate mitochondria and the mitochondrial permeability transition pore. This review summarizes how mitochondrial pathobiology might contribute to neuronal death in AD, PD, and ALS and could serve as a target for drug therapy.
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Shoshan-Barmatz V, Keinan N, Abu-Hamad S, Tyomkin D, Aram L. Apoptosis is regulated by the VDAC1 N-terminal region and by VDAC oligomerization: release of cytochrome c, AIF and Smac/Diablo. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1281-91. [PMID: 20214874 DOI: 10.1016/j.bbabio.2010.03.003] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 02/09/2010] [Accepted: 03/02/2010] [Indexed: 01/28/2023]
Abstract
Mitochondria, central to basic life functions due to their generation of cellular energy, also serve as the venue for cellular decisions leading to apoptosis. A key protein in mitochondria-mediated apoptosis is the voltage-dependent anion channel (VDAC), which also mediates the exchange of metabolites and energy between the cytosol and the mitochondria. In this study, the functions played by the N-terminal region of VDAC1 and by VDAC1 oligomerization in the release of cytochrome c, Smac/Diablo and apoptosis-inducing factor (AIF) and subsequent apoptosis were addressed. We demonstrate that cells undergoing apoptosis induced by STS or cisplatin and expressing N-terminally truncated VDAC1 do not release cytochrome c, Smac/Diablo or AIF. Ruthenium red (RuR), AzRu, DIDS and hexokinase-I (HK-I), all known to interact with VDAC, inhibited the release of cytochrome c, Smac/Diablo and AIF, while RuR-mediated inhibition was not observed in cells expressing RuR-insensitive E72Q-VDAC1. These findings suggest that VDAC1 is involved in the release of not only cytochrome c but also of Smac/Diablo and AIF. We also demonstrate that apoptosis induction is associated with VDAC oligomerization, as revealed by chemical cross-linking and monitoring in living cells using Bioluminescence Resonance Energy Transfer. Apoptosis induction by STS, H2O2 or selenite augmented the formation of VDAC oligomers several fold. The results show VDAC1 to be a component of the apoptosis machinery and offer new insight into the functions of VDAC1 oligomerization in apoptosis and of the VDAC1 N-terminal domain in the release of apoptogenic proteins as well as into regulation of VDAC by anti-apoptotic proteins, such as HK and Bcl2.
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Affiliation(s)
- Varda Shoshan-Barmatz
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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80
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Novel Strategy for Treatment of Pulmonary Arterial Hypertension: Enhancement of Apoptosis. Lung 2010; 188:179-89. [DOI: 10.1007/s00408-010-9233-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 02/16/2010] [Indexed: 01/22/2023]
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81
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Lan CH, Sheng JQ, Fang DC, Meng QZ, Fan LL, Huang ZR. Involvement of VDAC1 and Bcl-2 family of proteins in VacA-induced cytochrome c release and apoptosis of gastric epithelial carcinoma cells. J Dig Dis 2010; 11:43-9. [PMID: 20132430 DOI: 10.1111/j.1751-2980.2009.00412.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE It is known that the vacuolating cytotoxin (VacA) could induce apoptosis. However, the mechanism remained to be elucidated. The aim of this study is to investigate the role of Bcl family of proteins (Bcl-2 and Bax) and the mitochondrial voltage-dependent anion channel (VDAC) in VacA-induced apoptosis of AGS cells. METHODS Plasmid pGBKT7-VacA p58 was constructed and transfected into the AGS cells. RT-PCR and Western blotting were used to determine the expressions of cytochrome c, caspase-3, Bax, Bcl-2 and VDAC1 mRNA and proteins. RESULTS VacA p58 can induce cytochrome c release and activate caspase-3 in AGS cells. It up-regulated the expressions of Bax and VDAC1 mRNA and proteins, and decreased the expression of Bcl-2 in AGS cells. CONCLUSION VacA p58 induces apoptosis in AGS cells. This apoptotic process is associated with the up-regulation of Bax/VDAC1 and downregulation of Bcl-2. These findings suggest that the release of cytochrome c by VacA p58 is mainly through VDAC-dependent and Bcl-2 family-dependent pathways.
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Affiliation(s)
- Chun Hui Lan
- Department of Gastroenterology, Daping Hospital, Third Military Medical College, Chongqing, China.
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82
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Mitochondrial m-calpain plays a role in the release of truncated apoptosis-inducing factor from the mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1793:1848-59. [DOI: 10.1016/j.bbamcr.2009.10.002] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 09/19/2009] [Accepted: 10/06/2009] [Indexed: 12/13/2022]
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Ca2+ concentrations are key determinants of ischemia-reperfusion-induced apoptosis: significance for the molecular mechanism of Bcl-2 action. Appl Biochem Biotechnol 2009; 160:1968-77. [PMID: 19763897 DOI: 10.1007/s12010-009-8761-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 08/17/2009] [Indexed: 11/27/2022]
Abstract
The mechanism of action of the anti-apoptotic oncogene Bcl-2 and Ca2+ regulation in ischemia-reperfusion injury is still obscure. In this present study, we investigated mitochondrial Ca2+ overloads and mechanism of action of Bcl-2. Eighteen Wistar rats were divided into sham-operated control group (I) (n = 6), ischemia and reperfusion group (II) (n = 6), and amlodipine-treated group (1 mg kg(-1) body weight/daily by oral route for 7 days before inducing ischemia-reperfusion maneuver) (III) (n = 6). Rats were subjected to 1 h of hepatic ischemia followed by 3-h reperfusion. Mitochondrial Ca2+ content was determined and damage was confirmed by transmission electron microscopy. Decrease of mitochondrial Ca2+ level is related to reduction of apoptosis and cellular changes, viz. increased Bcl-2 expression followed by reduction in secondary endoplasmic reticulum, whereas ischemia/reperfusion group shows overloading Ca2+ ions and decrease in Bcl-2 expression as compared to sham-operated rats. Thus, Bcl-2-dependent reduction of Ca2+ is an important component of the anti-apoptotic program in ischemia-reperfusion injury.
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Abstract
Proper cell activity requires an efficient exchange of molecules between mitochondria and cytoplasm. Lying in the outer mitochondrial membrane, VDAC assumes a crucial position in the cell, forming the main interface between the mitochondrial and the cellular metabolisms. As such, it has been recognized that VDAC plays a crucial role in regulating the metabolic and energetic functions of mitochondria. Indeed, down-regulation of VDAC1 expression by shRNA leads to a decrease in energy production and cell growth. VDAC has also been recognized as a key protein in mitochondria-mediated apoptosis through its involvement in the release of apoptotic proteins located in the inter-membranal space and as the proposed target of pro- and anti-apoptotic members of the Bcl2-family and of hexokinase. Questions, however, remain as to if and how VDAC mediates the transfer of apoptotic proteins from the inter-membranal space to the cytosol. The diameter of the VDAC pore is only about 2.5-3 nm, insufficient for the passage of a folded protein like cytochrome c. New work, however, suggests that pore formation involves the assembly of homo-oligomers of VDAC or hetero-oligomers composed of VDAC and pro-apoptotic proteins, such as Bax. Thus, VDAC appears to represent a convergence point for a variety of cell survival and cell death signals. This review provides insight into the central role of VDAC in mammalian cell life and death, emphasizing VDAC function in the regulation of mitochondria-mediated apoptosis and, as such, its potential as a rational target for new therapeutics.
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85
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Abstract
VDAC channels are ancient, highly-conserved voltage-gated channels in the mitochondrial outer membrane. They are the pathways by which metabolites travel between the cytosol and mitochondria. They are involved in the apoptotic process and probably other functions as well. The lack of specific inhibitors has hampered research in the past but now phosphorothioate oligonucleotides can serve this function. These molecules were generated to be stable in the cytosol of cells but, unlike the oligonucleotides with the physiological phosphodiester linkage, these have the ability to bind to and block VDAC channels. They are potent, specific, and available commercially. At 1 microM concentration they block VDAC channels in mitochondria but do not affect the respiration complexes, the adenine nucleotide translocator or the ATP synthase.
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86
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Mannella CA, Kinnally KW. Reflections on VDAC as a voltage-gated channel and a mitochondrial regulator. J Bioenerg Biomembr 2009; 40:149-55. [PMID: 18648913 DOI: 10.1007/s10863-008-9143-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
There is excellent agreement between the electrophysiological properties and the structure of the mitochondrial outer membrane protein, VDAC, ex vivo. However, the inference that the well-defined canonical "open" state of the VDAC pore is the normal physiological state of the channel in vivo is being challenged by several lines of evidence. Knowing the atomic structure of the detergent solubilized protein, a long sought after goal, will not be sufficient to understand the functioning of this channel protein. In addition, detailed information about VDAC's topology in the outer membrane of intact mitochondria, and the structural changes that it undergoes in response to different stimuli in the cell will be needed to define its physiological functions and regulation.
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Affiliation(s)
- Carmen A Mannella
- Resource for Visualization of Biological Complexity, Wadsworth Center, Albany, NY 12201-0509, USA
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87
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Kusano T, Tateda C, Berberich T, Takahashi Y. Voltage-dependent anion channels: their roles in plant defense and cell death. PLANT CELL REPORTS 2009; 28:1301-1308. [PMID: 19585120 DOI: 10.1007/s00299-009-0741-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 06/23/2009] [Accepted: 06/23/2009] [Indexed: 05/28/2023]
Abstract
The voltage-dependent anion channels (VDACs), mitochondrial outer membrane components, are present in organisms from fungi to animals and plants. They are thought to function in the regulation of metabolite transport between mitochondria and the cytoplasm. Sufficient knowledge on plant VDACs has been accumulated, so that we can here summarize the current information. Then, the involvement of mitochondria in plant defense and cell death is overviewed. While, in mammals, it is suggested that VDAC, also known as a component of the permeability transition pore (PTP) complex formed in the junction site of mitochondrial outer and inner membrane, is a key player in mitochondria-mediated cell death, little is known about the role of plant VDACs in this process. We have shown that plant VDACs are involved in mitochondria-mediated cell death and in defense against a non-host pathogen. In light of the current findings, we discuss the role of the PTP complex and VDAC as its component in plant pathogen defense and cell death.
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Affiliation(s)
- Tomonobu Kusano
- Laboratory of Plant Molecular and Cellular Biology, Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai-City, Miyagi, 980-8577, Japan.
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88
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Martínez-Abundis E, Correa F, Pavón N, Zazueta C. Bax distribution into mitochondrial detergent-resistant microdomains is related to ceramide and cholesterol content in postischemic hearts. FEBS J 2009; 276:5579-88. [PMID: 19694802 DOI: 10.1111/j.1742-4658.2009.07239.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
*Diverse changes have been described in mitochondria of apoptotic cells: the phospholipid content is modified, ceramide and GD3 concentrations increase, the cristae structure is modified, and nonresident proteins are recruited into the mitochondrial membranes. In particular, Bax, a Bcl-2 family member protein, moves from the cytosol to the mitochondria, inducing cytochrome c release. Modifications of the content and distribution of specific lipids in the mitochondrial membranes, along with the well-known participation of the mitochondrial permeability transition pore in triggering apoptosis, led us to propose that lipid microdomains in mitochondria could coexist as structural elements with some of the mitochondrial permeability transition pore-forming proteins and with members of the Bcl-2 family. In this work, we demonstrated that Bax was associated preferentially with mitochondrial detergent-resistant membranes (mDRMs) in reperfused rat hearts, a well-known apoptotic model. Bax insertion into mDRMs correlated with cytochrome c release from such mitochondria. Bax location in mDRMs was associated with both the voltage-dependent anion channel and the adenine nucleotide translocator, two mitochondrial permeability transition pore-forming proteins. Interestingly, the voltage-dependent anion channel was more abundant in the mDRM fraction than in the Triton X-100-soluble fraction. Ceramide and cholesterol contents were higher in mDRMs from reperfused hearts. Our results suggest that membrane microenvironments enriched in cholesterol and ceramide in mitochondria favor Bax translocation to this organelle, fostering propagation of the apoptotic cascade.
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Affiliation(s)
- Eduardo Martínez-Abundis
- Departamento de Bioquímica, Instituto Nacional de Cardiología, 'Ignacio Chávez', Col. Sección XVI, México City, Mexico
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89
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Galluzzi L, Morselli E, Kepp O, Vitale I, Rigoni A, Vacchelli E, Michaud M, Zischka H, Castedo M, Kroemer G. Mitochondrial gateways to cancer. Mol Aspects Med 2009; 31:1-20. [PMID: 19698742 DOI: 10.1016/j.mam.2009.08.002] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 12/29/2022]
Abstract
Mitochondria are required for cellular survival, yet can also orchestrate cell death. The peculiar biochemical properties of these organelles, which are intimately linked to their compartmentalized ultrastructure, provide an optimal microenvironment for multiple biosynthetic and bioenergetic pathways. Most intracellular ATP is generated by mitochondrial respiration, which also represents the most relevant source of intracellular reactive oxygen species. Mitochondria participate in a plethora of anabolic pathways, including cholesterol, cardiolipin, heme and nucleotide biosynthesis. Moreover, mitochondria integrate numerous pro-survival and pro-death signals, thereby exerting a decisive control over several biochemical cascades leading to cell death, in particular the intrinsic pathway of apoptosis. Therefore, it is not surprising that cancer cells often manifest the deregulation of one or several mitochondrial functions. The six classical hallmarks of cancer (i.e., limitless replication, self-provision of proliferative stimuli, insensitivity to antiproliferative signals, disabled apoptosis, sustained angiogenesis, invasiveness/metastatic potential), as well as other common features of tumors (i.e., avoidance of the immune response, enhanced anabolic metabolism, disabled autophagy) may directly or indirectly implicate deregulated mitochondria. In this review, we discuss several mechanisms by which mitochondria can contribute to malignant transformation and tumor progression.
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Affiliation(s)
- Lorenzo Galluzzi
- INSERM, U848, Institut Gustave Roussy, PR1, 39 Rue Camille Desmoulins, F-94805 Villejuif, France
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90
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Dorai H, Kyung YS, Ellis D, Kinney C, Lin C, Jan D, Moore G, Betenbaugh MJ. Expression of anti-apoptosis genes alters lactate metabolism of Chinese Hamster Ovary cells in culture. Biotechnol Bioeng 2009; 103:592-608. [DOI: 10.1002/bit.22269] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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91
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Toriumi K, Oma Y, Mimoto A, Futai E, Sasagawa N, Turk B, Ishiura S. Polyalanine tracts directly induce the release of cytochrome c, independently of the mitochondrial permeability transition pore, leading to apoptosis. Genes Cells 2009; 14:751-7. [PMID: 19486166 DOI: 10.1111/j.1365-2443.2009.01307.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In recent years, several novel types of disorder caused by the expansion of triplet repeats in specific genes have been characterized; in the "polyalanine diseases", these expanded repeats result in proteins with aberrantly elongated polyalanine tracts. In this study, we fused expanded polyalanine tracts to yellow fluorescent protein to examine their physical interaction with mitochondria. Tracts containing more than 23 alanine repeats were found to physically associate with mitochondria, strongly suggesting that an interaction between polyalanine tracts and mitochondria is a contributing factor in the pathology of polyalanine diseases. Furthermore, in in vitro experiments, polyalanine tracts induced release of cytochrome c from mitochondria and caspase-3 activation, independently of the mitochondrial permeability transition pore. These results suggest that oligomerized polyalanine tracts might induce the rupture of the mitochondrial membrane, the subsequent release of cytochrome c, and apoptosis. This novel mechanism for polyalanine tract cytotoxicity might be common to the pathogenesis of all polyalanine diseases. Further investigation of this mechanism might aid the development of therapies for these diseases.
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Affiliation(s)
- Kazuya Toriumi
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan
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92
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Oppenheim MLS, Hargreaves IP, Pope S, Land JM, Heales SJR. Mitochondrial cytochrome c release: a factor to consider in mitochondrial disease? J Inherit Metab Dis 2009; 32:269-73. [PMID: 19169843 DOI: 10.1007/s10545-009-1061-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 12/19/2008] [Accepted: 12/22/2008] [Indexed: 10/21/2022]
Abstract
The pathogenesis of mitochondrial disorders has largely focused on the impairment of cellular energy metabolism. However, mitochondrial dysfunction has also been implicated as a factor in the initiation of apoptosis due to the translocation of cytochrome c, from mitochondria to the cytosol, and the subsequent cleavage of pro-caspase 3. In this study, we determined the cytochrome c content of cytosols (skeletal muscle) prepared from 22 patients with evidence of compromised mitochondrial electron transport chain enzyme activity and 26 disease controls. The cytochrome c content of the mitochondrial electron transport chain-deficient group was found to be significantly (p < 0.02) elevated when compared with the control group (63.7 +/- 15.5 versus 27.7 +/- 2.5 ng/mg protein). Furthermore, a relationship between the cytosolic cytochrome c content of skeletal muscle and complex I and complex IV activities was demonstrated. Such data raise the possibility that mitochondrial cytochrome c release may be a feature of mitochondrial disorders, particularly for those patients with marked deficiencies of respiratory chain enzymes. Whether initiation of apoptosis occurs as a direct consequence of this cytochrome c release has not been fully evaluated here. However, for one patient with the greatest documented cytosolic cytochrome c content, caspase 3 could be demonstrated in the cytosolic preparation. Further work is required in order to establish whether a relationship also exists between caspase 3 formation and the magnitude of respiratory chain deficiency.
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Affiliation(s)
- M L S Oppenheim
- Neurometabolic Unit, National Hospital for Neurology and Neurosurgery, Queen Square, London, WC1N 3BG, UK
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93
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Schafer B, Quispe J, Choudhary V, Chipuk JE, Ajero TG, Du H, Schneiter R, Kuwana T. Mitochondrial outer membrane proteins assist Bid in Bax-mediated lipidic pore formation. Mol Biol Cell 2009; 20:2276-85. [PMID: 19244344 DOI: 10.1091/mbc.e08-10-1056] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mitochondrial outer membrane permeabilization (MOMP) is a critical step in apoptosis and is regulated by Bcl-2 family proteins. In vitro systems using cardiolipin-containing liposomes have demonstrated the key features of MOMP induced by Bax and cleaved Bid; however, the nature of the "pores" and how they are formed remain obscure. We found that mitochondrial outer membranes contained very little cardiolipin, far less than that required for liposome permeabilization, despite their responsiveness to Bcl-2 family proteins. Strikingly, the incorporation of isolated mitochondrial outer membrane (MOM) proteins into liposomes lacking cardiolipin conferred responsiveness to cleaved Bid and Bax. Cardiolipin dependence was observed only when permeabilization was induced with cleaved Bid but not with Bid or Bim BH3 peptide or oligomerized Bax. Therefore, we conclude that MOM proteins specifically assist cleaved Bid in Bax-mediated permeabilization. Cryoelectron microscopy of cardiolipin-liposomes revealed that cleaved Bid and Bax produced large round holes with diameters of 25-100 nm, suggestive of lipidic pores. In sum, we propose that activated Bax induces lipidic pore formation and that MOM proteins assist cleaved Bid in this process in the absence of cardiolipin.
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Affiliation(s)
- Blanca Schafer
- Department of Pathology, University of Iowa Carver College of Medicine, Iowa City, 52242, USA
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94
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Probing the orientation of yeast VDAC1 in vivo. FEBS Lett 2009; 583:739-42. [DOI: 10.1016/j.febslet.2009.01.039] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2008] [Revised: 01/13/2009] [Accepted: 01/14/2009] [Indexed: 11/18/2022]
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95
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Tateda C, Yamashita K, Takahashi F, Kusano T, Takahashi Y. Plant voltage-dependent anion channels are involved in host defense against Pseudomonas cichorii and in Bax-induced cell death. PLANT CELL REPORTS 2009; 28:41-51. [PMID: 18953543 DOI: 10.1007/s00299-008-0630-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Revised: 10/08/2008] [Accepted: 10/12/2008] [Indexed: 05/09/2023]
Abstract
The voltage-dependent anion channel (VDAC) is a major outer mitochondrial membrane protein. It is well documented that VDAC plays an important role in apoptosis, a kind of programmed cell death, in mammalian systems. However, little is known about the role of the plant counterpart during the process of plant-specific cell death such as pathogen-induced hypersensitive response. To address this issue, we isolated three VDAC full-length cDNAs (NtVDAC1-3) from Nicotiana tabacum. The deduced products, NtVDACs, share 78-85% identity and retain the conserved eukaryotic mitochondrial porin signature distal to their C-terminal regions. Mitochondrial localization of three NtVDACs in plant cells was confirmed via a green fluorescent protein fusion method. Then, we addressed the main issue concerning pathogenesis relation. The N. benthamiana orthologues of NtVDACs were upregulated by challenge with the non-host pathogen Pseudomonas cichorii, but not after challenge with the virulent pathogen P. syringae pv. tabaci. Both the pharmaceutical inhibition of VDAC and silencing of NbVDACs genes compromised the non-host resistance against P. cichorii, suggesting the involvement of VDACs in defense against non-host pathogen. Involvement of NbVDACs in Bax-mediated cell death was also verified using a similar approach.
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Affiliation(s)
- Chika Tateda
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba, Sendai, Miyagi, 980-8577, Japan
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96
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Nawarak J, Huang-Liu R, Kao SH, Liao HH, Sinchaikul S, Chen ST, Cheng SL. Proteomics analysis of A375 human malignant melanoma cells in response to arbutin treatment. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1794:159-67. [PMID: 18996230 DOI: 10.1016/j.bbapap.2008.09.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 09/12/2008] [Accepted: 09/29/2008] [Indexed: 12/23/2022]
Abstract
Although the toxicogenomics of A375 human malignant melanoma cells treated with arbutin have been elucidated using DNA microarray, the proteomics of the cellular response to this compound are still poorly understood. In this study, we performed proteomic analyses to investigate the anticancer effect of arbutin on the protein expression profile in A375 cells. After treatment with arbutin (8 microg/ml) for 24, 48 and 72 h, the proteomic profiles of control and arbutin-treated A375 cells were compared, and 26 differentially expressed proteins (7 upregulated and 19 downregulated proteins) were identified by MALDI-Q-TOF MS and MS/MS. Among these proteins, 13 isoforms of six identical proteins were observed. Bioinformatic tools were used to search for protein function and to predict protein interactions. The interaction network of 14 differentially expressed proteins was found to be correlated with the downstream regulation of p53 tumor suppressor and cell apoptosis. In addition, three upregulated proteins (14-3-3G, VDAC-1 and p53) and five downregulated proteins (ENPL, ENOA, IMDH2, PRDX1 and VIME) in arbutin-treated A375 cells were validated by RT-PCR analysis. These proteins were found to play important roles in the suppression of cancer development.
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Affiliation(s)
- Jiraporn Nawarak
- Institute of Biological Chemistry and Genomics Research Center, Academia Sinica, Taipei 11529, Taiwan
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97
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Kmita H. Channels of the Outer Membrane ofSaccharomyces cerevisiaeMitochondria: Cooperation and Regulation. Toxicol Mech Methods 2008; 14:13-7. [DOI: 10.1080/15376520490257365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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98
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Cottet S, Schorderet DF. Triggering of Bcl-2-related pathway is associated with apoptosis of photoreceptors in Rpe65-/- mouse model of Leber's congenital amaurosis. Apoptosis 2008; 13:329-42. [PMID: 18274907 DOI: 10.1007/s10495-008-0180-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mutations in RPE65 protein is characterized by the loss of photoreceptors, although the molecular pathways triggering retinal cell death remain largely unresolved. The role of the Bcl-2 family of proteins in retinal degeneration is still controversial. However, alteration in Bcl-2-related proteins has been observed in several models of retinal injury. In particular, Bax has been suggested to play a crucial role in apoptotic pathways in murine glaucoma model as well as in retinal detachment-associated cell death. We demonstrated that Bcl-2-related signaling pathway is involved in Rpe65-dependent apoptosis of photoreceptors during development of the disease. Pro-apoptotic Bax alpha and beta isoforms were upregulated in diseased retina. This was associated with a progressive reduction of anti-apoptotic Bcl-2, reflecting imbalanced Bcl-2/Bax ratio as the disease progresses. Moreover, specific translocation of Bax beta from cytosol to mitochondria was observed in Rpe65-deficient retina. This correlated with the initiation of photoreceptor cell loss at 4 months of age, and further increased during disease development. Altogether, these data suggest that Bcl-2-apoptotic pathway plays a crucial role in Leber's congenital amaurosis disease. They further highlight a new regulatory mechanism of Bax-dependent apoptosis based on regulated expression and activation of specific isoforms of this protein.
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Affiliation(s)
- Sandra Cottet
- Institute for Research in Ophthalmology (IRO), Avenue Grand-Champsec 64, 1950, Sion 4, Switzerland.
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99
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Sanderson TH, Kumar R, Sullivan JM, Krause GS. Insulin blocks cytochrome c release in the reperfused brain through PI3-K signaling and by promoting Bax/Bcl-XL binding. J Neurochem 2008; 106:1248-58. [PMID: 18518905 DOI: 10.1111/j.1471-4159.2008.05473.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The critical event of the intrinsic pathway of apoptosis following transient global brain ischemia is the release of cytochrome c from the mitochondria. In vitro studies have shown that insulin can signal specifically via phosphatidylinositol-3-OH-kinase (PI3-K) and Akt to prevent cytochrome c release. Therefore, insulin may exert its neuroprotective effects during brain reperfusion by blocking cytochrome c release. We hypothesized that insulin acts through PI3-K, Akt, and Bcl-2 family proteins to inhibit cytochrome c release following transient global brain ischemia. We found that a single bolus of insulin given immediately upon reperfusion inhibited cytochrome c release for at least 24 h, and produced a fivefold improvement in neuronal survival at 14 days. Moreover, insulin's ability to inhibit cytochrome c release was completely dependent on PI3-K signaling and insulin induces phosphorylation of Akt through PI3-K. In untreated animals, there was an increase in mitochondrial Bax at 6 h of reperfusion, and Bax binding to Bcl-X(L) was disrupted at the mitochondria. Insulin prevented both these events in a PI3-K-dependent manner. In summary, insulin regulates cytochrome c release through PI3-K likely by activating Akt, promoting the binding between Bax and Bcl-X(L), and by preventing Bax translocation to the mitochondria.
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Affiliation(s)
- Thomas H Sanderson
- Department of Emergency Medicine, Wayne State University, Detroit, Michigan 48201, USA
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100
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Abstract
It was recently asserted that the voltage-dependent anion channel (VDAC) serves as a global regulator, or governor, of mitochondrial function (Lemasters and Holmuhamedov, Biochim Biophys Acta 1762:181-190, 2006). Indeed, VDAC, positioned on the interface between mitochondria and the cytosol (Colombini, Mol Cell Biochem 256:107-115, 2004), is at the control point of mitochondria life and death. This large channel plays the role of a "switch" that defines in which direction mitochondria will go: to normal respiration or to suppression of mitochondria metabolism that leads to apoptosis and cell death. As the most abundant protein in the mitochondrial outer membrane (MOM), VDAC is known to be responsible for ATP/ADP exchange and for the fluxes of other metabolites across MOM. It controls them by switching between the open and "closed" states that are virtually impermeable to ATP and ADP. This control has dual importance: in maintaining normal mitochondria respiration and in triggering apoptosis when cytochrome c and other apoptogenic factors are released from the intermembrane space into the cytosol. Emerging evidence indicates that VDAC closure promotes apoptotic signals without direct involvement of VDAC in the permeability transition pore or hypothetical Bax-containing cytochrome c permeable pores. VDAC gating has been studied extensively for the last 30 years on reconstituted VDAC channels. In this review we focus exclusively on physiologically relevant regulators of VDAC gating such as endogenous cytosolic proteins and mitochondrial lipids. Closure of VDAC induced by such dissimilar cytosolic proteins as pro-apoptotic tBid and dimeric tubulin is compared to show that the involved mechanisms are rather distinct. While tBid mostly modulates VDAC voltage gating, tubulin blocks the channel with the efficiency of blockage controlled by voltage. We also discuss how characteristic mitochondrial lipids, phospatidylethanolamine and cardiolipin, could regulate VDAC gating. Overall, we demonstrate that VDAC gating is not just an observation made under artificial conditions of channel reconstitution but is a major mechanism of MOM permeability control.
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Affiliation(s)
- Tatiana K. Rostovtseva
- Laboratory of Physical and Structural Biology, Program in Physical Biology, NICHD, National Institutes of Health, Bldg. 9, Rm. 1E-106, 9000 Rockville Pike, Bethesda, MD 20892, USA, e-mail:
| | - Sergey M. Bezrukov
- Laboratory of Physical and Structural Biology, Program in Physical Biology, NICHD, National Institutes of Health, Bldg. 9, Rm. 1E-106, 9000 Rockville Pike, Bethesda, MD 20892, USA, e-mail:
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