scholarly journals XopQ induced stromule formation in Nicotiana benthamiana is causally linked to ETI signaling and depends on ADR1 and NRG1

2021 ◽  
Author(s):  
Jennifer Prautsch ◽  
Jessica L. Erickson ◽  
Sedef Özyürek ◽  
Rahel Gormannns ◽  
Lars Franke ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Nicotiana Benthamiana ◽  
Double Mutant ◽  
Plant Immunity ◽  
Signaling Cascade ◽  
Nuclear Dynamics ◽  
Hypersensitive Cell Death ◽  
Host Cell Death ◽  
Dependent Cell

In Nicotiana benthamiana, expression of the Xanthomonas effector XopQ triggers ROQ1-dependent ETI responses and in parallel accumulation of plastids around the nucleus and the formation of stromules. Both processes were proposed to contribute to ETI-related hypersensitive cell death and thereby to plant immunity. Whether these reactions are directly connected to ETI signaling events has not been tested. Here we utilized transient expression experiments to determine whether XopQ-mediated plastid reactions are a result of XopQ perception by ROQ1 or a consequence of XopQ virulence activity. We find that N. benthamiana mutants lacking ROQ1, both RNLs (NRG1 and ADR1) or EDS1, fail to elicit XopQ-dependent host cell death and stromule formation. Mutants lacking only NRG1 lost XopQ-dependent cell death but retained some stromule induction that was abolished in the RNL double mutant. This analysis aligns XopQ-induced stromules with the ETI signaling cascade but not to host programmed cell death. Furthermore, data reveal that XopQ-triggered plastid clustering is not strictly linked to stromule formation during ETI. Our data suggest that stromule formation, in contrast to chloroplast peri-nuclear dynamics, is an integral part of the N. benthamiana ETI response and that both RNL sub-types play a role in this ETI response.

Mitochondrial dynamics in yeast cell death and aging

2011 ◽  
Vol 39 (5) ◽  
pp. 1520-1526 ◽  
Author(s):  
Ralf J. Braun ◽  
Benedikt Westermann
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Mitochondrial Dynamics ◽  
Progressive Increase ◽  
Mitochondrial Morphology ◽  
Aging Research ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cell Death Pathways ◽  
Dependent Cell ◽  
Mitochondrial Networks

Mitochondria play crucial roles in programmed cell death and aging. Different stimuli activate distinct mitochondrion-dependent cell death pathways, and aging is associated with a progressive increase in mitochondrial damage, culminating in oxidative stress and cellular dysfunction. Mitochondria are highly dynamic organelles that constantly fuse and divide, forming either interconnected mitochondrial networks or separated fragmented mitochondria. These processes are believed to provide a mitochondrial quality control system and enable an effective adaptation of the mitochondrial compartment to the metabolic needs of the cell. The baker's yeast, Saccharomyces cerevisiae, is an established model for programmed cell death and aging research. The present review summarizes how mitochondrial morphology is altered on induction of cell death or on aging and how this correlates with the induction of different cell death pathways in yeast. We highlight the roles of the components of the mitochondrial fusion and fission machinery that affect and regulate cell death and aging.

scholarly journals Mouse cytomegalovirus M36 and M45 death suppressors cooperate to prevent inflammation resulting from antiviral programmed cell death pathways

2017 ◽  
Vol 114 (13) ◽  
pp. E2786-E2795 ◽  
Author(s):  
Lisa P. Daley-Bauer ◽  
Linda Roback ◽  
Lynsey N. Crosby ◽  
A. Louise McCormick ◽  
Yanjun Feng ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Double Mutant ◽  
Kinase Domain ◽  
Murine Cytomegalovirus ◽  
Caspase 8 ◽  
Interacting Protein ◽  
Antiviral Responses ◽  
Cell Death Pathways ◽  
Infected Cells

The complex interplay between caspase-8 and receptor-interacting protein (RIP) kinase RIP 3 (RIPK3) driving extrinsic apoptosis and necroptosis is not fully understood. Murine cytomegalovirus triggers both apoptosis and necroptosis in infected cells; however, encoded inhibitors of caspase-8 activity (M36) and RIP3 signaling (M45) suppress these antiviral responses. Here, we report that this virus activates caspase-8 in macrophages to trigger apoptosis that gives rise to secondary necroptosis. Infection with double-mutant ΔM36/M45mutRHIM virus reveals a signaling pattern in which caspase-8 activates caspase-3 to drive apoptosis with subsequent RIP3-dependent activation of mixed lineage kinase domain-like (MLKL) leading to necroptosis. This combined cell death signaling is highly inflammatory, greater than either apoptosis induced by ΔM36 or necroptosis induced by M45mutRHIM virus. IL-6 production by macrophages is dramatically increased during double-mutant virus infection and correlates with faster antiviral responses in the host. Collaboratively, M36 and M45 target caspase-8 and RIP3 pathways together to suppress this proinflammatory cell death. This study reveals the effect of antiviral programmed cell death pathways on inflammation, shows that caspase-8 activation may go hand-in-hand with necroptosis in macrophages, and revises current understanding of independent and collaborative functions of M36 and M45 in blocking apoptotic and necroptotic cell death responses.

scholarly journals The NLR helper protein NRC3 but not NRC1 is required for Pto-mediated cell death in Nicotiana benthamiana

2015 ◽  
Author(s):  
Chih-Hang Wu ◽  
Khaoula Belhaj ◽  
Tolga O. Bozkurt ◽  
Sophien Kamoun
Keyword(s):  
Cell Death ◽  
Nicotiana Benthamiana ◽  
Rna Silencing ◽  
Genetic Complementation ◽  
Hypersensitive Cell Death ◽  
Immune Receptors ◽  
Disease Resistance Protein ◽  
Resistance Protein ◽  
Solanaceous Plants ◽  
Lrr Protein

Intracellular immune receptors of the nucleotide-binding leucine-rich repeat (NB-LRR or NLR) proteins often function in pairs, with "helper" proteins required for the activity of "sensors" that mediate pathogen recognition. The NLR helper NRC1 (NB-LRR protein required for HR-associated cell death 1) has been described as a signalling hub required for the cell death mediated by both cell surface and intracellular immune receptors in the model plant Nicotiana benthamiana. However, this work predates the availability of the N. benthamiana genome and whether NRC1 is indeed required for the reported phenotypes has not been confirmed. Here, we investigated the NRC family of solanaceous plants using a combination of genome annotation, phylogenetics, gene silencing and genetic complementation experiments. We discovered that a paralog of NRC1, we termed NRC3, is required for the hypersensitive cell death triggered by the disease resistance protein Pto but not Rx and Mi-1.2. NRC3 may also contribute to the hypersensitive cell death triggered by the receptor-like protein Cf-4. Our results highlight the importance of applying genetic complementation to validate gene function in RNA silencing experiments.

scholarly journals Cucumber Mildew Resistance Locus O Interacts with Calmodulin and Regulates Plant Cell Death Associated with Plant Immunity

2019 ◽  
Vol 20 (12) ◽  
pp. 2995 ◽  
Author(s):  
Guangchao Yu ◽  
Xiangyu Wang ◽  
Qiumin Chen ◽  
Na Cui ◽  
Yang Yu ◽  
...  
Keyword(s):  
Cell Death ◽  
Fluorescent Protein ◽  
Plant Immunity ◽  
Bimolecular Fluorescence Complementation ◽  
Marker Genes ◽  
Resistance Locus ◽  
Callose Deposition ◽  
Cucumis Sativus L ◽  
Hypersensitive Cell Death ◽  
Mildew Resistance

Pathogen-induced cell death is closely related to plant disease susceptibility and resistance. The cucumber (Cucumis sativus L.) mildew resistance locus O (CsMLO1) and calmodulin (CsCaM3) genes, as molecular components, are linked to nonhost resistance and hypersensitive cell death. In this study, we demonstrate that CsMLO1 interacts with CsCaM3 via yeast two-hybrid, firefly luciferase (LUC) complementation and bimolecular fluorescence complementation (BiFC) experiments. A subcellular localization analysis of green fluorescent protein (GFP) fusion reveals that CsCaM3 is transferred from the cytoplasm to the plasma membrane in Nicotiana benthamiana, and CsCaM3 green fluorescence is significantly attenuated via the coexpression of CsMLO1 and CsCaM3. CsMLO1 negatively regulates CsCaM3 expression in transiently transformed cucumbers, and hypersensitive cell death is disrupted by CsCaM3 and/or CsMLO1 expression under Corynespora cassiicola infection. Additionally, CsMLO1 silencing significantly enhances the expression of reactive oxygen species (ROS)-related genes (CsPO1, CsRbohD, and CsRbohF), defense marker genes (CsPR1 and CsPR3) and callose deposition-related gene (CsGSL) in infected cucumbers. These results suggest that the interaction of CsMLO1 with CsCaM3 may act as a cell death regulator associated with plant immunity and disease.

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