scholarly journals Bacterial Porin Disrupts Mitochondrial Membrane Potential and Sensitizes Host Cells to Apoptosis

2010 ◽  
Vol 98 (3) ◽  
pp. 245a
Author(s):  
Anke Harsman ◽  
Michael Meinecke ◽  
Thomas Rudel ◽  
Joachim Rassow ◽  
Richard Wagner
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Host Cells

scholarly journals Reduction in the mitochondrial membrane potential of Toxoplasma gondii after invasion of host cells

1984 ◽  
Vol 70 (1) ◽  
pp. 73-81
Author(s):  
K. Tanabe ◽  
K. Murakami
Keyword(s):  
Membrane Potential ◽  
Toxoplasma Gondii ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Protozoan Parasite ◽  
Fluorescent Dye ◽  
Host Cells ◽  
Intracellular Parasites ◽  
Neutral Compounds ◽  
Infected Cells

The membrane potential of Toxoplasma gondii, an obligatory intracellular protozoan parasite, was monitored with the cationic permeant fluorescent dye rhodamine 123 (R123). Fluorescence microscopy revealed R123 to be partitioned predominantly in a restricted part of the parasite, which consisted of twisted or branched tubules, or of granular bodies. These structures were frequently connected to each other. The dye retention by these structures was markedly reduced by treating R123-labelled parasites with the proton ionophore, carbonylcyanide m-chlorophenylhydrazone, the potassium ionophore, valinomycin and the inhibitor of electron transport, antimycin A. Thus, these structures are regarded as the parasite mitochondria. Another cationic fluorescent dye, rhodamine 6G, stained the parasite mitochondria, whereas a negatively charged fluorescent dye, fluorescein, and the neutral compounds, rhodamine 110 and rhodamine B, did not. This fact indicates that R123 monitored the parasite mitochondrial membrane potential. T. gondii-infected 3T3 cells were also stained with R123. In contrast to the mitochondria of extracellular parasites, those of intracellular parasites failed to take up the dye. The absence of fluorescence in intracellular parasites persisted until the infected host cells ruptured and liberated daughter parasites 1 day after infection. Parasites, liberated from the host cells, either spontaneously or artificially by passing the infected cells through a 27G needle, regained the ability to take up the dye. After direct microinjection of R123 into the vacuole in which the parasite grows and multiples, the dye appeared in the host-cell mitochondria but not in the parasite's mitochondria. Thus, we conclude that the mitochondrial membrane potential of T. gondii was reduced after invasion of host cells by the parasite.

scholarly journals Vaccinia virus induces apoptosis of infected macrophages

2002 ◽  
Vol 83 (11) ◽  
pp. 2821-2832 ◽  
Author(s):  
Zuzana Humlová ◽  
Martin Vokurka ◽  
Mariano Esteban ◽  
Zora Mělková
Keyword(s):  
Gene Expression ◽  
Nitric Oxide ◽  
Membrane Potential ◽  
Vaccinia Virus ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Host Cells ◽  
Early Gene ◽  
Early Gene Expression ◽  
Induction Of Apoptosis

Vaccinia virus (VV) infects a broad range of host cells, and while it usually causes their lysis (i.e. necrosis), the nature of the cell-death phenomenon is not well understood. In this study, we show that VV induces apoptosis of cells of the murine macrophage line J774.G8, as revealed by morphological signs, DNA ladder formation, changes of mitochondrial membrane potential and annexin-V positivity. Apoptosis occurred in both untreated and IFN-γ-pretreated macrophages, and could not be inhibited by aminoguanidine, a relatively specific inhibitor of inducible nitric oxide synthase. Inhibition of VV DNA synthesis and late gene expression by cytosine arabinoside also did not prevent apoptosis, while heat- or psoralen/UV-inactivated VV did not cause any apoptosis. Thus, VV early gene expression seems to be required for induction of apoptosis. At the cellular level, infection with VV induced a decrease in the levels of Bcl-xL, an anti-apoptotic member of the Bcl-2 family. The importance of loss of Bcl-xL was demonstrated by prevention of VV-mediated apoptosis on expression of Bcl-2, a functional homologue of Bcl-xL. Our findings provide evidence that induction of apoptosis by VV in macrophages requires virus early gene expression, does not involve nitric oxide, induces a decrease in mitochondrial membrane potential and is associated with altered levels of Bcl-xL.

Benzodiazepine-423, an Inhibitor of Mitochondrial Respiration, Causes Selective Apoptosis of Activated Lymphocytes and Reverses Experimental GVHD While Preserving GVL Effects.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 68-68
Author(s):  
Erin Gatza ◽  
Shawn G. Clouthier ◽  
Pavan Reddy ◽  
Chen Liu ◽  
Anthony W. Opipari ◽  
...  
Keyword(s):  
T Cells ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Respiration ◽  
Mitochondrial Membrane ◽  
Ex Vivo ◽  
Host Cells ◽  
Activated Lymphocytes ◽  
Damage Indices ◽  
Ifn Γ

Abstract Benzodiazepine (Bz)-423 is a benzodiazepine derivative that targets activated lymphocytes through the mitochondrial F1F0-ATPase, causing loss of mitochondrial membrane potential and apoptosis without affecting resting lymphocytes. We tested Bz-423 in a non-irradiated B6-Ly5.2 → B6D2F1 model of graft-versus-host disease (GVHD) where donor cells were labeled with CFSE to discriminate 3 days after injection between activated (CFSElo) and unactivated (CFSEhi) Ly5.2+ donor or host Ly5.1+ lymphocytes. Compared to controls, Bz-423 caused loss of mitochondrial membrane polarization within 6h of delivery as measured by 3,3’-dihexyloxacarbocyanine iodide (DiOC6(3)) staining in both activated donor CD4+ (12.6% vs 3.3%, p=0.002) and activated CD8+ (12.9% vs 3.0%, p<0.001) T cells but not in unactivated donor or host cells. Loss of mitochondrial membrane potential was followed by selective apoptosis (Annexin-V+) of donor CD4+ (34.9% vs 16.5%, p=0.04) and CD8+ (29.8% vs 12.2%, p=0.03) T cells. Intraperitoneal injection of 60mg/kg Bz-423 3 times weekly beginning 7d after GVHD induction significantly reduced mortality (50% vs 100%, p<0.02). We next used Bz-423 in a miHA-disparate, CD8+ T cell-mediated model of GVHD (C3H.SW → B6) in which B6 hosts received 9 Gy of TBI followed by injection of 5x106 C3H.SW BM cells and 4x106 T cells. We initiated Bz-423 injections 7d after BMT, when GVHD was already established. The drug significantly reduced GVHD clinical scores and improved survival compared to controls (74% vs 29%, p≤0.02). Bz-423 also significantly reduced quantitative GVHD histologic damage indices in the liver (3.6 vs 11.2, p<0.03) and the GI tract (7.0 vs 15.8, p<0.02). Complete donor engraftment was observed in all animals. Bz-423 reduced IFN-γ, a known mediator of GVHD, in the serum (8.4 vs 21.7 pg/ml, p<0.03) and decreased IFN-γ+CD8+ effector spleen T cells (0.64x105 vs 2.2x105, p=0.008), but did not impair the lysis of tumor targets by CD8+ T cells ex vivo. We tested Bz-423 next in a graft-versus-leukemia (GVL) model where EL-4 lymphoma cells (4x103) that are syngeneic to B6 recipients were injected on the day of BMT. No recipients of syngeneic BMT survived EL-4 challenge (0/12) and no untreated allogeneic BMT survived GVHD (0/12) but 9/14 (64%) of Bz-423 treated allogeneic recipients were alive on day 50 without evidence of lymphoma (p=0.003, Fig 1a). We confirmed the effectiveness of Bz-423 in a third model of GVHD to MHC differences (Balb/c → B6) where again Bz-423 significantly reduced all clinical, biochemical and histologic GVHD parameters and improved day 60 survival (58% vs 8%, p<0.002). Bz-423 also preserved GVL effects in this model where 50% of recipients survived without evidence of EL-4 lymphoma compared to 0% of controls (p<0.04, Fig 1b). We conclude that Bz-423, a first-in-class compound that selectively inhibits mitochondrial respiration and causes apoptosis of activated lymphocytes, can reverse experimental GVHD while preserving beneficial GVL effects. Figure Figure

scholarly journals Bacterial Porin Disrupts Mitochondrial Membrane Potential and Sensitizes Host Cells to Apoptosis

2009 ◽  
Vol 5 (10) ◽  
pp. e1000629 ◽  
Author(s):  
Vera Kozjak-Pavlovic ◽  
Elke A. Dian-Lothrop ◽  
Michael Meinecke ◽  
Oliver Kepp ◽  
Katharina Ross ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Membrane ◽  
Host Cells

Platelets apoptosis in rats after global brain ischemia

2018 ◽  
pp. 27-35
Author(s):  
А.А. Соколовская ◽  
Э.Д. Вирюс ◽  
В.В. Александрин ◽  
А.С. Роткина ◽  
К.А. Никифорова ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Ischemic Stroke ◽  
Membrane Potential ◽  
Mitochondrial Membrane Potential ◽  
Brain Ischemia ◽  
Mitochondrial Membrane ◽  
Male Rats ◽  
Global Brain Ischemia ◽  
Platelet Apoptosis ◽  
Global Brain

Цель исследования. Ишемические повреждения головного мозга, являются одной из наиболее частой причин инвалидности и смертности во всем мире. Недавно была установлена роль апоптоза тромбоцитов в патофизиологии инсульта, однако его механизмы до сих пор остаются невыясненными. Несмотря на различные экспериментальные модели, направленные на мониторинг апоптоза тромбоцитов, результаты, относительно изучения и выявления апоптоза тромбоцитов при ишемии головного мозга у крыс, весьма немногочисленны. Цель исследования - анализ апоптоза тромбоцитов с помощью метода проточной цитофлуориметрии на модели глобальной ишемии мозга у крыс. Методика. В экспериментах использовано 6 крыс-самцов Вистар в возрасте от 5 до 6 мес., разделенных на 2 группы: интактный контроль (К) и глобальная ишемия головного мозга. Модель глобальной ишемии головного мозга у крыс воспроизводилась путём билатеральной окклюзии общих сонных артерий на фоне гипотензии. Уровень системного артериального давления снижали посредством кровопотери до 40-45 мм рт. ст. Суспензию тромбоцитов крыс получали методом гельфильтрации с использованием сефарозы 2B. Для анализа экстернализации фосфатидилсерина (ФС) тромбоциты крыс инкубировали с Аннексином V-PE в связывающем буфере. Для оценки митохондриального мембранного потенциала (ММП) тромбоциты инкубировали с катионным красителем JC-1. После инкубации образцы немедленно анализировали на проточном цитофлуориметре FACSCalibur (Becton Dickinson, США). Результаты. Согласно полученным данным, экстернализация ФС на тромбоцитах крыс, перенесших инсульт, была значительно выше (53,45 ± 4,21%), чем в контрольной группе крыс (5,27 ± 2,40%). Данный эффект подтверждается выраженной деполяризацией митохондриальных мембран (DYm). После экспериментальной ишемии мозга почти 40% тромбоцитов было деполяризовано. Заключение. Использованный в работе подбор методов и маркеров обеспечивает понимание механизмов апоптоза тромбоцитов как в экспериментальных, так и в клинических условиях. Полученные данные позволяют сделать заключение, что апоптоз тромбоцитов является одним из факторов развития глобальной ишемии головного мозга у крыс. Результаты могут быть использованы для понимания механизмов, участвующих в развитии ишемического повреждения, что, в свою очередь, может быть использовано при разработке новых терапевтических стратегий. Aim. Stroke is one of the most common causes of disability and mortality worldwide. Multiple experimental models of stroke have focused on monitoring of platelet apoptosis. However, studies on and detection of platelet apoptosis in rats with ischemic stroke are very scarce. We investigated platelet apoptosis in rats with global brain ischemia using flow cytometry. Methods. Experiments were carried out on healthy, adult Wistar male rats weighing 300-350 g. The rats were divided into the following 2 groups: intact rats and rats with global brain ischemia. Global brain ischemia was induced by two-vessel (2-VO) carotid occlusion in combination with hypotension. Systemic blood pressure was reduced by 40-45 mm Hg by inducing haemorrhage. Platelets were isolated by gel filtration on Sepharose 2B. For evaluation of phosphatidylserine (PS) externalization, platelets were incubated with Annexin V-PE and analyzed on FACSCalibur (BD Biosciences). Mitochondrial membrane potential (DY) was measured during platelets apoptosis using JC-1, a mitochondrial membrane potential indicator. Platelets were analyzed by flow cytometry immediately after the incubation. Results. PS externalization on platelets was significantly greater after global brain ischemia (53.45 ± 4.21%) than in the control group (5.27 ± 2.40%). Pronounced depolarization of mitochondrial membrane potential (DYm) confirmed this finding. In the rat group with experimental brain ischemia, almost 40% (35.24 ± 5.21%) of platelets were depolarized. Conclusion. Our results provide insight into mechanisms involved in platelet apoptosis during ischemic stroke and can be used in further development of new therapeutic strategies.

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