scholarly journals Characterization of Metacaspases with Trypsin-Like Activity and Their Putative Role in Programmed Cell Death in the Protozoan Parasite Leishmania

2007 ◽  
Vol 6 (10) ◽  
pp. 1745-1757 ◽  
Author(s):  
Nancy Lee ◽  
Sreenivas Gannavaram ◽  
Angamuthu Selvapandiyan ◽  
Alain Debrabant
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Death ◽  
Programmed Cell Death ◽  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Protein Band ◽  
Mrna Levels ◽  
Enzymatic Assays ◽  
Rich Domain ◽  
Axenic Amastigotes

ABSTRACT In this report, we have characterized two metacaspases of Leishmania donovani, L. donovani metacaspase-1 (LdMC1) and LdMC2. These two proteins show 98% homology with each other, and both contain a characteristic C-terminal proline-rich domain. Both genes are transcribed in promastigotes and axenic amastigotes of L. donovani; however, LdMC1 shows increased mRNA levels in axenic amastigotes. An anti-LdMC antibody was obtained and showed reactivity with a single ∼42-kDa protein band in both promastigote and axenic amastigote parasite whole-cell lysates by Western blotting. Pulse-chase experiments suggest that LdMCs are not synthesized as proenzymes, and immunofluorescence studies show that LdMCs are associated with the acidocalcisome compartments of L. donovani. Enzymatic assays of immunoprecipitated LdMCs show that native LdMCs efficiently cleave trypsin substrates and are unable to cleave caspase-specific substrates. Consistently, LdMC activity is insensitive to caspase inhibitors and is efficiently inhibited by trypsin inhibitors, such as leupeptin, antipain, and N α-tosyl-l-lysine-chloromethyl ketone (TLCK). In addition, our results show that LdMC activity was induced in parasites treated with hydrogen peroxide, a known trigger of programmed cell death (PCD) in Leishmania and that parasites overexpressing metacaspases are more sensitive to hydrogen peroxide-induced PCD. These findings suggest that Leishmania metacaspases are not responsible for the caspase-like activities reported in this organism and suggest a possible role for LdMCs as effector molecules in Leishmania PCD.

Metronidazole induces programmed cell death in the protozoan parasite Blastocystis hominis

Microbiology ◽  
2004 ◽  
Vol 150 (1) ◽  
pp. 33-43 ◽  
Author(s):  
A. M. A. Nasirudeen ◽  
Yap Eu Hian ◽  
Mulkit Singh ◽  
Kevin S. W. Tan
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Protozoan Parasite ◽  
Blastocystis Hominis

scholarly journals Disuccinyl Betulin Triggers Metacaspase-Dependent Endonuclease G-Mediated Cell Death in Unicellular Protozoan Parasite Leishmania donovani

2014 ◽  
Vol 58 (4) ◽  
pp. 2186-2201 ◽  
Author(s):  
Sayan Chowdhury ◽  
Tulika Mukherjee ◽  
Somenath Roy Chowdhury ◽  
Souvik Sengupta ◽  
Sibabrata Mukhopadhyay ◽  
...  
Keyword(s):  
Cell Death ◽  
Leishmania Donovani ◽  
Protozoan Parasite ◽  
Degradation Process ◽  
Dna Lesions ◽  
Death Process ◽  
Unicellular Organism ◽  
Content Type ◽  
Atp Production ◽  
Endonuclease G

ABSTRACTThe unicellular organismLeishmaniaundergoes apoptosis-like cell death in response to external stress or exposure to antileishmanial agents. Here, we showed that 3-O,28-O-disuccinyl betulin (DiSB), a potent topoisomerase type IB inhibitor, induced parasitic cell death by generating oxidative stress. The characteristic feature of the death process resembled the programmed cell death (PCD) seen in higher eukaryotes. In the current study, the generation of reactive oxygen species (ROS), followed by the depolarization of mitochondrial membrane potential (ΔΨm), caused a loss in ATP production inLeishmaniaparasites. This further gave positive feedback to produce a large amount of ROS, which in turn caused oxidative DNA lesions and genomic DNA fragmentation. The treatment of promastigotes with DiSB induced high expression levels of metacaspase protein that led to cell death in this unicellular organism. The PCD was insensitive to benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD-fmk), suggesting that the death process was not associated with the activation of caspases. DiSB treatment translocatedLeishmania donovaniendonuclease G (LdEndoG) from mitochondria to the nucleus, which was responsible for the DNA degradation process. Conditional antisense knockdown ofL. donovanimetacaspase (LdMC), as well as EndoG, -subverted death of the parasite and rescued cell cycle arrest in G1phase. The present study on the effector molecules associated with the PCD pathway of the parasite should help to manifest the mechanisms of PCD and also might be exploited in antileishmanial chemotherapy.

scholarly journals Hydrogen peroxide as a signal controlling plant programmed cell death

2005 ◽  
Vol 168 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Tsanko S. Gechev ◽  
Jacques Hille
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Death ◽  
Programmed Cell Death ◽  
Signaling Pathways ◽  
Microarray Analysis ◽  
Plant Cell ◽  
Full Genome ◽  
Genome Coverage ◽  
Regulatory Mutants

Hydrogen peroxide (H2O2) has established itself as a key player in stress and programmed cell death responses, but little is known about the signaling pathways leading from H2O2 to programmed cell death in plants. Recently, identification of key regulatory mutants and near-full genome coverage microarray analysis of H2O2-induced cell death have begun to unravel the complexity of the H2O2 network. This review also describes a novel link between H2O2 and sphingolipids, two signals that can interplay and regulate plant cell death.

scholarly journals Treatment of melanoma cells with the synthetic retinoid CD437 induces apoptosis via activation of AP-1 in vitro, and causes growth inhibition in xenografts in vivo.

1996 ◽  
Vol 135 (6) ◽  
pp. 1889-1898 ◽  
Author(s):  
D Schadendorf ◽  
M A Kern ◽  
M Artuc ◽  
H L Pahl ◽  
T Rosenbach ◽  
...  
Keyword(s):  
Cell Death ◽  
Malignant Melanoma ◽  
Programmed Cell Death ◽  
Melanoma Cells ◽  
Human Melanoma ◽  
Mrna Levels ◽  
Synthetic Retinoid ◽  
Human Melanoma Cells

Human malignant melanoma is notoriously resistant to pharmacological modulation. We describe here for the first time that the synthetic retinoid CD437 has a strong dose-dependent antiproliferative effect on human melanoma cells (IC50: 5 x 10(-6) M) via the induction of programmed cell death, as judged by analysis of cell morphology, electron microscopical features, and DNA fragmentation. Programmed cell death was preceded by a strong activation of the AP-1 complex in CD437-treated cells as demonstrated by gel retardation and chloramphenicol transferase (CAT) assays. Northern blot analysis showed a time-dependent increase in the expression of c-fos and c-jun encoding components of AP-1, whereas bcl-2 and p53 mRNA levels remained constant. CD437 also exhibited a strong growth inhibitory effect on MeWo melanoma cells in a xenograft model. In tissue sections of CD437-treated MeWo tumors from these animals, apoptotic melanoma cells and c-fos overexpressing cells were colocalized by TdT-mediated deoxyuridine triphosphate-digoxigenin nick end labeling (TUNEL) staining and in situ hybridization. Taken together, this report identifies CD437 as a retinoid that activates and upregulates the transcription factor AP-1, leading eventually to programmed cell death of exposed human melanoma cells in vitro and in vivo. Further studies are needed to evaluate whether synthetic retinoids such as CD437 represent a new class of retinoids, which may open up new ways to a more effective therapy of malignant melanoma.

scholarly journals Expression of a Mitochondrial Peroxiredoxin Prevents Programmed Cell Death in Leishmania donovani

2006 ◽  
Vol 5 (5) ◽  
pp. 861-870 ◽  
Author(s):  
Simone Harder ◽  
Meike Bente ◽  
Kerstin Isermann ◽  
Iris Bruchhaus
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Mitochondrial Membrane ◽  
Leishmania Donovani ◽  
Physiological Role ◽  
Logarithmic Phase ◽  
Insect Vector ◽  
Oxygen Species ◽  
Late Logarithmic Phase

ABSTRACT Leishmania promastigote cells transmitted by the insect vector get phagocytosed by macrophages and convert into the amastigote form. During development and transformation, the parasites are exposed to various concentrations of reactive oxygen species, which can induce programmed cell death (PCD). We show that a mitochondrial peroxiredoxin (LdmPrx) protects Leishmania donovani from PCD. Whereas this peroxiredoxin is restricted to the kinetoplast area in promastigotes, it covers the entire mitochondrion in amastigotes, accompanied by dramatically increased expression. A similar change in the expression pattern was observed during the growth of Leishmania from the early to the late logarithmic phase. Recombinant LdmPrx shows typical peroxiredoxin-like enzyme activity. It is able to detoxify organic and inorganic peroxides and prevents DNA from hydroxyl radical-induced damage. Most notably, Leishmania parasites overexpressing this peroxiredoxin are protected from hydrogen peroxide-induced PCD. This protection is also seen in promastigotes grown to the late logarithmic phase, also characterized by high expression of this peroxiredoxin. Apparently, the physiological role of this peroxiredoxin is stabilization of the mitochondrial membrane potential and, as a consequence, inhibition of PCD through removal of peroxides.

scholarly journals TheFusariummycotoxin deoxynivalenol elicits hydrogen peroxide production, programmed cell death and defence responses in wheat

2008 ◽  
Vol 9 (4) ◽  
pp. 435-445 ◽  
Author(s):  
OLIVIA J. DESMOND ◽  
JOHN M. MANNERS ◽  
AMBER E. STEPHENS ◽  
DONALD J. MACLEAN ◽  
PEER M. SCHENK ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Death ◽  
Programmed Cell Death ◽  
Hydrogen Peroxide Production ◽  
Defence Responses

Hydrogen peroxide promotes programmed cell death and salicylic acid accumulation during the induced production of sesquiterpenes in cultured cell suspensions of Aquilaria sinensis

2015 ◽  
Vol 42 (4) ◽  
pp. 337 ◽  
Author(s):  
Juan Liu ◽  
Yanhong Xu ◽  
Zheng Zhang ◽  
Jianhe Wei
Keyword(s):  
Hydrogen Peroxide ◽  
Cell Death ◽  
Salicylic Acid ◽  
Programmed Cell Death ◽  
Cell Suspensions ◽  
Valuable Insight ◽  
Aquilaria Sinensis ◽  
Defensive Reaction ◽  
Cultured Cell ◽  
Salicylic Acid Accumulation

Aquilaria sinensis (Lour.) Gilg produces a highly valuable agarwood characterised by a diverse array of sesquiterpenes and chromone derivatives that can protect wounded trees against potential herbivores and pathogens. A defensive reaction on the part of the plant has been proposed as the key reason for agarwood formation, but the issue of whether programmed cell death (PCD), an important process of plant immune responding, is involved in agarwood formation, still needs to be clarified. In this study, treatment of cultured cell suspensions with hydrogen peroxide (H2O2) induced the production of sesquiterpenes due to endogenous accumulation of salicylic acid (SA) and elevations in the expression of sesquiterpene biosynthetic genes. Moreover, PCD was stimulated by H2O2 in cultured cell suspensions of A. sinensis due to the induction of caspase activity, upregulated expression of metacaspases and cytochrome c, and SA accumulation. Our findings demonstrate for the first time that H2O2 stimulates PCD, SA accumulation and sesquiterpene production in cultured cell suspensions of A. sinensis. Furthermore, results from this study provide a valuable insight into investigations of the potential interactions between sesquiterpene synthesis and PCD during agarwood formation.

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