共查询到20条相似文献,搜索用时 15 毫秒
1.
A tale of two mitochondrial channels,MAC and PTP,in apoptosis 总被引:1,自引:0,他引:1
Kinnally KW Antonsson B 《Apoptosis : an international journal on programmed cell death》2007,12(5):857-868
The crucial step in the intrinsic, or mitochondrial, apoptotic pathway is permeabilization of the mitochondrial outer membrane.
Permeabilization triggers release of apoptogenic factors, such as cytochrome c, from the mitochondrial intermembrane space into the cytosol where these factors ensure propagation of the apoptotic cascade
and execution of cell death. However, the mechanism(s) underlying permeabilization of the outer membrane remain controversial.
Two mechanisms, involving opening of two different mitochondrial channels, have been proposed to be responsible for the permeabilization;
the permeability transition pore (PTP) in the inner membrane and the mitochondrial apoptosis-induced channel (MAC) in the
outer membrane. Opening of PTP would lead to matrix swelling, subsequent rupture of the outer membrane, and an unspecific
release of intermembrane proteins into the cytosol. However, many believe PTP opening is a consequence of apoptosis and this
channel is thought to principally play a role in necrosis, not apoptosis. Activation of MAC is exquisitely regulated by Bcl-2
family proteins, which are the sentinels of apoptosis. MAC provides specific pores in the outer membrane for the passage of
intermembrane proteins, in particular cytochrome c, to the cytosol. The electrophysiological characteristics of MAC are very similar to Bax channels and depletion of Bax significantly
diminishes MAC activity, suggesting that Bax is an essential constituent of MAC in some systems. The characteristics of various
mitochondrial channels and Bax are compared. The involvement of MAC and PTP activities in apoptosis of disease and their pharmacology
are discussed. 相似文献
2.
Mitochondria play a pivotal role in the regulation of apoptosis. An imbalance in apoptosis can lead to disease. Unscheduled apoptosis has been linked to neurodegeneration while inhibition of apoptosis can cause cancer. An early and key event during apoptosis is the release of factors from mitochondria. In apoptosis the mitochondrial outer membrane becomes permeable, leading to release of apoptogenic factors into the cytosol. One such factor, cytochrome c, is an electron carrier of the respiratory chain normally trapped within the mitochondrial intermembrane space. Many apoptotic studies investigate mitochondrial outer membrane permeabilization (MOMP) by monitoring the release of cytochrome c. Here, we describe three reliable techniques that detect cytochrome c release from mitochondria, through subcellular fractionation or immunocytochemistry and fluorescence microscopy, or isolated mitochondria and recombinant Bax and t-Bid proteins in vitro. These techniques will help to identify mechanisms and characterize factors regulating MOMP. 相似文献
3.
Guo L Pietkiewicz D Pavlov EV Grigoriev SM Kasianowicz JJ Dejean LM Korsmeyer SJ Antonsson B Kinnally KW 《American journal of physiology. Cell physiology》2004,286(5):C1109-C1117
Recent studies indicate that cytochrome c is released early in apoptosis without loss of integrity of the mitochondrial outer membrane in some cell types. The high-conductance mitochondrial apoptosis-induced channel (MAC) forms in the outer membrane early in apoptosis of FL5.12 cells. Physiological (micromolar) levels of cytochrome c alter MAC activity, and these effects are referred to as types 1 and 2. Type 1 effects are consistent with a partitioning of cytochrome c into the pore of MAC and include a modest decrease in conductance that is dose and voltage dependent, reversible, and has an increase in noise. Type 2 effects may correspond to "plugging" of the pore or destabilization of the open state. Type 2 effects are a dose-dependent, voltage-independent, and irreversible decrease in conductance. MAC is a heterogeneous channel with variable conductance. Cytochrome c affects MAC in a pore size-dependent manner, with maximal effects of cytochrome c on MAC with conductance of 1.95.4 nS. The effects of cytochrome c, RNase A, and high salt on MAC indicate that size, rather than charge, is crucial. The effects of dextran molecules of various sizes indicate that the pore diameter of MAC is slightly larger than that of 17-kDa dextran, which should be sufficient to allow the passage of 12-kDa cytochrome c. These findings are consistent with the notion that MAC is the pore through which cytochrome c is released from mitochondria during apoptosis. patch clamp; ion channels 相似文献
4.
Cardiolipin: Setting the beat of apoptosis 总被引:4,自引:0,他引:4
Gonzalvez F Gottlieb E 《Apoptosis : an international journal on programmed cell death》2007,12(5):877-885
Cardiolipin (CL) is a mitochondria-specific phospholipid which is known to be intimately linked with the mitochondrial bioenergetic
machinery. Accumulating evidence now suggests that this unique lipid also has active roles in several of the mitochondria-dependant
steps of apoptosis. CL is closely associated with cytochrome c at the outer leaflet of the mitochondrial inner membrane. This interaction makes the process of cytochrome c release from mitochondria more complex than previously assumed, requiring more than pore formation in the mitochondrial outer
membrane. While CL peroxidation could be crucial for enabling cytochrome c dissociation from the mitochondrial inner membrane, cytochrome c itself catalyzes CL peroxidation. Moreover, peroxy-CL directly activates the release of cytochrome c and other apoptogenic factors from the mitochondria. CL is also directly involved in mitochondrial outer membrane permeabilization
by enabling docking and activation of pro-apoptotic Bcl-2 proteins. It appears therefore that CL has multiple roles in apoptosis
and that CL metabolism contributes to the complexity of the apoptotic process. 相似文献
5.
Regulation of the mitochondrial apoptosis-induced channel, MAC, by BCL-2 family proteins 总被引:3,自引:0,他引:3
Dejean LM Martinez-Caballero S Manon S Kinnally KW 《Biochimica et biophysica acta》2006,1762(2):191-201
Programmed cell death or apoptosis is central to many physiological processes and pathological conditions such as organogenesis, tissue homeostasis, cancer, and neurodegenerative diseases. Bcl-2 family proteins tightly control this cell death program by regulating the permeabilization of the mitochondrial outer membrane and, hence, the release of cytochrome c and other pro-apoptotic factors. Control of the formation of the mitochondrial apoptosis-induced channel, or MAC, is central to the regulation of apoptosis by Bcl-2 family proteins. MAC is detected early in apoptosis by patch clamping the mitochondrial outer membrane. The focus of this review is on the regulation of MAC activity by Bcl-2 family proteins. The role of MAC as the putative cytochrome c release channel during early apoptosis and insights concerning its molecular composition are also discussed. 相似文献
6.
Sonia Martinez-Caballero Laurent M. Dejean Michael S. Kinnally Kyoung Joon Oh Carmen A. Mannella Kathleen W. Kinnally 《The Journal of biological chemistry》2009,284(18):12235-12245
Although Bcl-2 family proteins control intrinsic apoptosis, the mechanisms
underlying this regulation are incompletely understood. Patch clamp studies of
mitochondria isolated from cells deficient in one or both of the pro-apoptotic
proteins Bax and Bak show that at least one of the proteins must be present
for formation of the cytochrome c-translocating channel,
mitochondrial apoptosis-induced channel (MAC), and that the single channel
behaviors of MACs containing exclusively Bax or Bak are similar. Truncated Bid
catalyzes MAC formation in isolated mitochondria containing Bax and/or Bak
with a time course of minutes and does not require VDAC1 or VDAC3.
Mathematical analysis of the stepwise changes in conductance associated with
MAC formation is consistent with pore assembly by a barrel-stave model.
Assuming the staves are two transmembrane α-helices in Bax and Bak,
mature MAC pores would typically contain ∼9 monomers and have diameters of
5.5–6 nm. The mitochondrial permeability data are inconsistent with
formation of lipidic pores capable of transporting megadalton-sized
macromolecules as observed with recombinant Bax in liposomes.Permeabilization of the mitochondrial outer membrane is the commitment step
in intrinsic apoptosis. This process is tightly regulated by Bcl-2 family
proteins that control formation of the megachannel mitochondrial
apoptosis-induced channel
(MAC)2 in this
membrane. MAC formation correlates with release of pro-apoptotic factors,
including cytochrome c from the intermembrane space into the cytosol,
and initiates apoptosis
(1–7).MAC is absent from normal mitochondria but forms in the outer membrane
early in apoptosis, reaching peak conductances of 1.5–5 nS. This channel
is formed in the presence of the multidomain pro-apoptotic proteins Bax and/or
Bak
(8–13),
and may be composed of these proteins along with other components
(14,
15). Unlike Bax, Bak is
normally a resident of the mitochondrial outer membrane and is bound to VDAC2,
another outer membrane protein
(16). However, Bak is not
available for oligomerization until another pro-apoptotic protein, like t-Bid,
disrupts the interaction of Bak with VDAC2. In contrast, most Bax is located
in the cytoplasm until an apoptotic signal induces the translocation of Bax to
the outer membrane of mitochondria and eventual Bax oligomerization in this
same membrane (14,
17).Bax and Bak have multiple putative transmembrane domains; the amphipathic
helices 5 and 6 of Bax are predicted to form, at least in part, the pore of
the cytochrome c release channel
(18). Bax lacking helices 5
and 6 does not translocate to mitochondria nor cause cytochrome c
release (19,
20). Given the structural
similarities between Bax and Bak, the same helices may be important in
formation of the MAC pore by both proteins
(21). Although Bax and Bak are
certainly involved in MAC formation, the exact molecular composition of this
channel remains unknown.In this study we report that Bax and Bak are functionally redundant with
regard to MAC formation and cytochrome c release in mouse embryonic
fibroblasts (MEF). This is true despite the fact that Bak normally resides in
the outer membrane, whereas Bax is generally translocated to this membrane to
induce MAC formation. Our experimental design bypasses Bax translocation and
any underlying autocatalytic mechanism that might be involved
(22). Instead, it focuses on
formation of the MAC pore. Early MAC-associated conductance increments are
relatively small, suggesting that Bax-dependent formation of the cytochrome
c-permeable pore does not occur prior to membrane insertion of Bax.
Mathematical modeling of the conductance changes indicates that, if MAC is a
circular pore assembled by sequential addition of helices 5 and 6 from Bax
and/or Bak monomers, the mature, cytochrome c transport-competent
pore is likely a 9–10-mer of these proteins. 相似文献
7.
Maureen O. Ripple Michelle Abajian Roger Springett 《Apoptosis : an international journal on programmed cell death》2010,15(5):563-573
Visible spectroscopy was used to measure real-time changes in the oxidation state of cytochrome c (cyt c) and the a-cytochromes (cyt aa3) of cytochrome oxidase during mitochondrial outer membrane permeabilization (MOMP) initiated by anisomycin in HL-60 cells.
The oxidation state of mitochondrial cyt c was found to be ≈62% oxidized before MOMP and became ≈70% oxidized after MOMP. In contrast, the cytosolic pool of cyt c was found to be almost fully reduced. This oxidation change allows cyt c release to be continuously and quantitatively monitored in real time. Anoxia and antimycin were used to fully reduce and
fully oxidize, respectively, the mitochondrial pool of cyt c and it was found that the release of cyt c was independent of it oxidation state consistent with a simple model of cyt c passively diffusing down a concentration gradient through a pore or tear in the outer membrane. After MOMP was complete,
the flux of cyt c diffusing back into the mitochondria was measured from the residual mitochondrial oxygen consumption after complete inhibition
of the bc1 with antimycin and myxothiazol. The outer membrane was found to be highly permeable after MOMP implying that the reduction
of cyt c in the cytosol must be very rapid. The permeability of the outer membrane measured in this study would result in the release
of cyt c with a time constant of less than 1 s. 相似文献
8.
Maria Piqu Montserrat Barragn Mireia Dalmau Beatriz Bellosillo Gabriel Pons Joan Gil 《FEBS letters》2000,480(2-3)
Aspirin and other non-steroidal anti-inflammatory drugs induce apoptosis in many cell types. Although the involvement of caspases has been demonstrated, the mechanism leading to caspase activation remains unknown. We have studied the role of the mitochondrial pathway in aspirin-induced apoptosis. The apoptotic effect of aspirin was analyzed in different cell lines (Jurkat, MOLT-4, Raji and HL-60) showing induction of mitochondrial cytochrome c release and caspases 9, 3 and 8 processing. Furthermore, early aspirin-induced cytochrome c release was not affected by the caspase inhibitor Z-VAD·fmk and preceded loss of mitochondrial membrane potential. Therefore, aspirin-induced apoptosis involves caspase activation through cytochrome c release. 相似文献
9.
Pablo M. Peixoto Shin-Young Ryu Dawn Pietkiewicz Pruzansky Andrew Gilmore 《Biochemical and biophysical research communications》2009,390(1):38-725
The death of one cell can precipitate the death of nearby cells in a process referred to as the bystander effect. We investigated whether mitochondrial apoptosis generated a bystander effect and, if so, by which pathway. Microinjection with cytochrome c mimicked function of the mitochondrial apoptosis-induced channel MAC and caused apoptosis of both target and nearby osteoblasts. This effect was suppressed by inhibiting gap junction intercellular communication. A bystander effect was also observed after exogenous expression of tBid, which facilitates MAC formation and cytochrome c release. Interestingly, in connexin-43 deficient osteoblasts, microinjection of cytochrome c induced apoptosis only in the target cell. These findings indicate that a death signal was generated downstream of MAC function and was transmitted through gap junctions to amplify apoptosis in neighboring cells. This concept may have implications in development of new therapeutic approaches. 相似文献
10.
Apoptosis is a phenomenon fundamental to higher eukaryotes and essential to mechanisms controlling tissue homeostasis. Bcl-2 family proteins tightly control this cell death program by regulating the permeabilization of the mitochondrial outer membrane and, hence, the release of cytochrome c and other proapoptotic factors. Mitochondrial apoptosis-induced channel (MAC) is the mitochondrial apoptosis-induced channel and is responsible for cytochrome c release early in apoptosis. MAC activity is detected by patch clamping mitochondria at the time of cytochrome c release. The Bcl-2 family proteins regulate apoptosis by controlling the formation of MAC. Depending on cell type and apoptotic inducer, Bax and/or Bak are structural component(s) of MAC. Overexpression of the antiapoptotic protein Bcl-2 eliminates MAC activity. The focus of this review is a biophysical characterization of MAC activity and its regulation by Bcl-2 family proteins, and ends with some discussion of therapeutic targets. 相似文献
11.
Eri Oyanagi Hiromi Yano Masataka Uchida Kozo Utsumi Junzo Sasaki 《Biochemical and biophysical research communications》2011,(1):61
Cardiovascular risks are frequently accompanied by high serum fatty acid levels. Although recent studies have shown that fatty acids affect mitochondrial function and induce cell apoptosis, l-carnitine is essential for the uptake of fatty acids by mitochondria, and may attenuate the mitochondrial dysfunction and apoptosis of cardiocytes. This study aimed to elucidate the activity of l-carnitine in the prevention on fatty acid-induced mitochondrial membrane permeability transition and cytochrome c release using isolated cardiac mitochondria from rats. Palmitoyl-CoA-induced mitochondrial respiration that was observed with l-carnitine was inhibited with oligomycin. The palmitoyl-CoA-induced mitochondrial membrane depolarization and swelling were greatly inhibited by the presence of l-carnitine. In ultrastructural observations, terminally swollen and ruptured mitochondria with little or no distinguishable cristae structures were induced by treatment with palmitoyl-CoA. However, the severe morphological damage in cardiac mitochondria was dramatically inhibited by pretreatment with l-carnitine. Treatment with l-carnitine also attenuated 4-hydroxy-l-phenylglycine- and rotenone-induced mitochondrial swelling even when the l-carnitine could not protect against the decrease in oxygen consumption associated with these inhibitors. Furthermore, l-carnitine completely inhibited palmitoyl-CoA-induced cytochrome c release. We concluded that l-carnitine is essential for cardiac mitochondria to attenuate the membrane permeability transition, and to maintain the ultrastructure and membrane stabilization, in the presence of high fatty acid β-oxidation. Consequently, the cells may be protected against apoptosis by l-carnitine through inhibition of the fatty acid-induced cytochrome c release. 相似文献
12.
Bcl‐2 family proteins are critical for the regulation of apoptosis, with the pro‐apoptotic members Bax essential for the release of cytochrome c from mitochondria in many instances. However, we found that Bax was activated after mitochondrial depolarization and the completion of cytochrome c release induced by photodynamic therapy (PDT) with the photosensitizer Photofrin in human lung adenocarcinoma cells (ASTC‐a‐1). Besides, knockdown of Bax expression by gene silencing had no effect on mitochondrial depolarization and cytochrome c release, indicating that Bax makes no contribution to mitochondrial outer membrane permeabilization (MOMP) following PDT. Further study revealed that Bax knockdown only slowed down the speed of cell death induced by PDT, indicating that Bax is not essential for PDT‐induced apoptosis. The fact that Bax knockdown totally inhibited the mitochondrial accumulation of dynamin‐related protein (Drp1) and Drp1 knockdown attenuated cell apoptosis suggest that Bax can promote PDT‐induced apoptosis through promoting Drp1 activation. Besides, Drp1 knockdown also failed to inhibit PDT‐induced cell death finally, indicating that Bax‐mediated Drp1's mitochondrial translocation is not essential for PDT‐induced cell apoptosis. On the other hand, we found that protein kinase Cδ (PKCδ), Bim L and glycogen synthase kinase 3β (GSK3β) were activated upon PDT treatment and might contribute to the activation of Bax under the condition. Taken together, Bax activation is not essential for MOMP but essential for Drp1‐mediated mitochondrial fission during the apoptosis caused by Photofrin‐PDT. J. Cell. Physiol. 226: 530–541, 2011. © 2010 Wiley‐Liss, Inc. 相似文献
13.
Rapak A Stasik I Ziolo E Strzadala L 《Apoptosis : an international journal on programmed cell death》2007,12(10):1873-1878
Nur77 is reported to undergo translocation to mitochondria in response to apoptotic signaling in a variety of cancer cell
lines. It was shown that on the mitochondrial membrane, Nur77 interacts with Bcl-2, leading to the conversion of this protein
from a protector to a killer with subsequent release of cytochrome c to the cytosol. Here it is shown that in thymic lymphoma cells resistant to calcium-mediated apoptosis, cytochrome c release is abolished despite of Nur77 mitochondrial targeting. However, cytochrome c release and apoptosis can be restored by treatment with FK506. Hence, the molecular target regulation of the sensitivity
of lymphoma cells to calcium signaling is associated with cytochrome c release and is FK506 sensitive. These results provide new insight into the role of FK506-sensitive factors as a critical
link between calcium signaling and resistance of lymphoma cells to death. 相似文献
14.
Laurent M. Dejean Shin-Young Ryu Sonia Martinez-Caballero Oscar Teijido Pablo M. Peixoto Kathleen W. Kinnally 《BBA》2010,1797(6-7):1231-1238
Apoptosis is an elemental form of programmed cell death; it is fundamental to higher eukaryotes and essential to mechanisms controlling tissue homeostasis. Apoptosis is also involved in many pathologies including cancer, neurodegenerative diseases, aging, and infarcts. This cell death program is tightly regulated by Bcl-2 family proteins by controlling the formation of the mitochondrial apoptosis-induced channel or MAC. Assembly of MAC corresponds to permeabilization of the mitochondrial outer membrane, which is the so called commitment step of apoptosis. MAC provides the pathway through the mitochondrial outer membrane for the release of cytochrome c and other pro-apoptotic factors from the intermembrane space. While overexpression of anti-apoptotic Bcl-2 eliminates MAC activity, oligomers of the pro-apoptotic members Bax and/or Bak are essential structural component(s) of MAC. Assembly of MAC from Bax or Bak was monitored in real time by directly patch-clamping mitochondria with micropipettes containing the sentinel tBid, a direct activator of Bax and Bak. Herein, a variety of high affinity inhibitors of MAC (iMAC) that may prove to be crucial tools in mechanistic studies have recently been identified. This review focuses on characterization of MAC activity, its regulation by Bcl-2 family proteins, and a discussion of how MAC can be pharmacologically turned on or off depending on the pathology to be treated. 相似文献
15.
Aubert M Pomeranz LE Blaho JA 《Apoptosis : an international journal on programmed cell death》2007,12(1):19-35
Expression of HSV-1 genes leads to the induction of apoptosis in human epithelial HEp-2 cells but the subsequent synthesis
of infected cell protein prevents the process from killing the cells. Thus, viruses unable to produce appropriate prevention
factors are apoptotic. We now report that the addition of either a pancaspase inhibitor or caspase-9-specific inhibitor prevented
cells infected with an apoptotic HSV-1 virus from undergoing cell death. This result indicated that HSV-1-dependent apoptosis
proceeds through the mitochondrial apoptotic pathway. However, the pancaspase inhibitor did not prevent the release of cytochrome
c from mitochondria, implying that caspase activation is not required for this induction of cytochrome c release by HSV-1. The release of cytochrome c was first detected at 9 hpi while caspase-9, caspase-3 and PARP processing were detected at 12 hpi. Finally, Bax accumulated
at mitochondria during apoptotic, but not wild type HSV-1 infection. Together, these findings indicate that HSV-1 blocks apoptosis
by precluding mitochondrial cytochrome c release in a caspase-independent manner and suggest Bax as a target in infected human epithelial cells. 相似文献
16.
Scorrano L 《Journal of bioenergetics and biomembranes》2005,37(3):165-170
During apoptosis, mitochondria undergo multiple changes that culminate in the release of cytochrome c and other proapoptotic cofactors. Recently, a role for previously overlooked morphological changes, fission of the mitochondrial reticulum and remodeling of mitochondrial cristae, has been suggested in mammalian cells and in developmental apoptosis of C. elegans. Mitochondrial morphology is determined by fusion and fission processes, controlled by a growing set of “mitochondria-shaping” proteins, whose levels and function appear to regulate the mitochondrial pathways of cell death. Expression of pro-fusion proteins, as well as of inhibition of pro-fission molecules reduces apoptosis, suggesting a linear relationship between fragmentation and death. Mechanisms by which mitochondrial fragmentation promotes apoptosis and interactions between fragmentation and remodeling of the inner membrane are largely unclear. A tempting, unifying hypothesis suggests that fission is coupled to cristae remodeling to maximize cytochrome c release. 相似文献
17.
Silva RD Manon S Gonçalves J Saraiva L Côrte-Real M 《Experimental cell research》2011,317(6):1379-790
Protein kinase Cα (PKCα) is a classical PKC isoform whose involvement in cell death is not completely understood. Bax, a major member of the Bcl-2 family, is required for apoptotic cell death and regulation of Bax translocation and insertion into the outer mitochondrial membrane is crucial for regulation of the apoptotic process. Here we show that PKCα increases the translocation and insertion of Bax c-myc (an active form of Bax) into the outer membrane of yeast mitochondria. This is associated with an increase in cytochrome c (cyt c) release, reactive oxygen species production (ROS), mitochondrial network fragmentation and cell death. This cell death process is regulated, since it correlates with an increase in autophagy but not with plasma membrane permeabilization. The observed increase in Bax c-myc translocation and insertion by PKCα is not due to Bax c-myc phosphorylation, and the higher cell death observed is independent of the PKCα kinase activity. PKCα may therefore have functions other than its kinase activity that aid in Bax c-myc translocation and insertion into mitochondria. Together, these results give a mechanistic insight on apoptosis regulation by PKCα through regulation of Bax insertion into mitochondria. 相似文献
18.
Cione E Tucci P Senatore V Perri M Trombino S Iemma F Picci N Genchi G 《Journal of bioenergetics and biomembranes》2008,40(1):19-26
Ferulic acid plays a chemopreventive role in cancer by inducing tumor cells apoptosis. As mitochondria play a key role in
the induction of apoptosis in many cells types, here we investigate the mitochondrial permeability transition (MPT) and the
release of cytochrome c induced by ferulic acid and its esters in rat testes mitochondria, in TM-3 and MLTC-1 cells. While ferulic acid, but not
its esters, induced MPT and cytochrome c release in rat testes isolated mitochondria, in TM-3 cells we found that both ferulic acid and its esters induced cytochrome
c release from mitochondria in a dose-dependent manner, suggesting a potential target of these compounds in the induction of
cell apoptosis. The apoptosis induced by ferulic acid is therefore associated with the mitochondrial pathway involving cytochrome
c release and caspase-3 activation.
Cione and Tucci have equally contributed to this article. 相似文献
19.
Phosphorothioate oligonucleotides reduce mitochondrial outer membrane permeability to ADP 总被引:2,自引:0,他引:2
Tan W Lai JC Miller P Stein CA Colombini M 《American journal of physiology. Cell physiology》2007,292(4):C1388-C1397
G3139, an antisense Bcl-2 phosphorothioate oligodeoxyribonucleotide, induces apoptosis in melanoma and other cancer cells. This apoptosis happens before and in the absence of the downregulation of Bcl-2 and thus seems to be Bcl-2-independent. Binding of G3139 to mitochondria and its ability to close voltage-dependent anion-selective channel (VDAC) have led to the hypothesis that G3139 acts, in part, by interacting with VDAC channels in the mitochondrial outer membrane (21). In this study, we demonstrate that G3139 is able to reduce the mitochondrial outer membrane permeability to ADP by a factor of 6 or 7 with a Ki between 0.2 and 0.5 µM. Because VDAC is responsible for this permeability, this result strengthens the aforesaid hypothesis. Other mitochondrial respiration components are not affected by [G3139] up to 1 µM. Higher levels begin to inhibit respiration rates, decrease light scattering and increase uncoupled respiration. These results agree with accumulating evidence that VDAC closure favors cytochrome c release. The speed of this effect (within 10 min) places it early in the apoptotic cascade with cytochrome c release occurring at later times. Other phosphorothioate oligonucleotides are also able to induce VDAC closure, and there is some length dependence. The phosphorothioate linkages are required to induce the reduction of outer membrane permeability. At levels below 1 µM, phosphorothioate oligonucleotides are the first specific tools to restrict mitochondrial outer membrane permeability. respiration; voltage-dependent anion-selective channel; apoptosis; cell death 相似文献
20.
Chen SP Wu JL Su YC Hong JR 《Apoptosis : an international journal on programmed cell death》2007,12(6):1043-1060
Nervous necrosis virus (NNV)-induced, host cell apoptosis mediates secondary necrosis by an ill-understood process. In this
study, redspotted grouper nervous necrosis virus (RGNNV) is shown to induce mitochondria-mediated necrotic cell death in GL-av
cells (fish cells) via cytochrome c release, and anti-apoptotic proteins are shown to protect these cells from death. Western blots revealed that cytochrome
c release coincided with disruption of mitochondrial ultrastructure and preceded necrosis, but did not correlate with caspases
activation. To identify the mediator(s) of this necrotic process, a protein synthesis inhibitor (cycloheximide; CHX; 0.33 μg/ml)
was used to block cytochrome c release as well as PS exposure and mitochondrial membrane permeability transition pore (MMP) loss. CHX (0.33 μg/ml) completely
blocked viral protein B2 expression, and partly blocked protein A, protein α, and a pro-apoptotic death protein (Bad) expression.
Overexpression of B2 gene increased necrotic-like cell death up to 30% at 48 h post-transfection, suggesting that newly synthesized protein (B2)
may be involved in this necrotic process. Finally, necrotic death was prevented by overexpression of Bcl-2 family proteins,
zfBcl-xL and xfMcl-1a. Thus, new protein synthesis and release of cytochrome c are required for RGNNV-induced necrotic cell death, which can be blocked by anti-apoptotic Bcl-2 members.
J.-L. Wu and J.-R. Hong contributed equally to the research. 相似文献