Effect of deleption of BnaA06FAH and BnaC05FAH on gene expression during programmed cell death in brassica napus.L
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ABSTRACT: Programmed cell death (PCD) is a genetically controlled pathway that plants can use to selectively eliminate redundant or damaged cells.The coordinated and sequential actions of lineage-specific transcription factors and epigenetic regulators are essential for the initiation of PCD. We used CRISPR/Cas9-mediated targeted mutagenesis to generate a series of transgene-free mutant lines either with single or double-null bnafah alleles. Among these mutant lines, the bnafah (deleption of BnaA06FAH and BnaC05FAH) double-null mutant line, rather than the bnaa06fah (deleption of BnaA06FAH) mutant line, exhibited PCD under short day (SD) condition. To gain deeper mechanistic understanding of PCD process, transcriptomic analyses of bnaa06fah and bnafah under LD(SD0), SD1 and SD2 were performed. Heatmap cluster of DEGs speculated that PCD may related to various redox regulation genes involved in antioxidant, ROS-responsive regulator and calcium signaling. Combined with the results of previous studies, our work showed that the expression levels of BnaC04CAT2, BnaA09/C09SAL1, BnaA08/C08ACO2, BnaA07/C06ERO1, BnaA08ACA1, BnaC04BIK1, BnaA09CRK36 and BnaA03CPK4 were significantly different and might be candidate hub genes of PCD.
Project description:We have published results demonstrating that UV-C induces apoptotic-like changes in Arabidopsis (Danon and Gallois FEBS lett (1998) 437: 131-136). The Programmed Cell Death "phenotype" of nucleus shape, DNA laddering caspase-like activity is similar to what has been described in other plant PCD. This demonstrates that UV-C is an appropriate and controllable trigger to study PCD in plants. Using selected mutants and a set of chosen conditions we are aiming at identifying genes that are part of the PCD pathways in plants and filter out the general stress response. We are asking for a medium size experiment knowing that additional microarray analysis are likely to be required to refine the results obtained. We are currently awaiting the results of Affymetrix RNAs hybridisation of PCD-induced wild type that will define the appropriate single time point of the proposed analysis. The rationale is to vary treatments in order to distinguish changes in gene transcription arising from general cellular stress responses to the trigger used from those specific to PCD: 1. We will use wild-type Arabidopsis seedlings as a negative control to provide the basal gene expression pattern. 2. A dose of UV-C radiation of 1KJ/m2. We will irradiate wild type with this non PCD-inducing dose of UV-C radiation to identify sets of genes that respond to UV-induced damage but whose expression is not linked to cell death. 3. A dose of UV-C radiation of 50 KJ/m2. We will irradiate wild type with a PCD-inducing dose of UV-C radiation to identify sets of genes that respond to UV-induced damage and cell death. 4. We have shown that the cell death induced by UV is light dependant, the control, sub-inducing dose and inducing dose treatments will be repeated and the plants kept in the dark until RNA sampling. In those conditions there is no PCD.
Project description:The Polycomb Repressive Complex 2 (PRC2) is well-known for its role in controlling developmental transitions by suppressing the premature expression of key developmental regulators. Previous work revealed that PRC2 also controls the onset of senescence, a form of developmental programmed cell death (PCD) in plants. Whether the induction of PCD in response to stress is similarly suppressed by the PRC2 remained largely unknown. In this study, we explored whether PCD triggered in response to immunity- and disease-promoting pathogen effectors is associated with changes in the distribution of the PRC2-mediated H3K27me3 histone modification in Arabidopsis thaliana. We furthermore tested the distribution of the heterochromatic histone mark H3K9me2, which is established, to a large extent, by the H3K9 methyltransferase KRYPTONITE, and occupies chromatin regions generally not targeted by PRC2. We report that effector-induced PCD caused major changes in the distribution of both repressive epigenetic modifications and that both modifications have a regulatory role and impact on the onset of PCD during pathogen infection. Our work highlights that the transition to pathogen-induced PCD is epigenetically controlled, revealing striking similarities to developmental PCD.
Project description:Transdifferentiation and changes of cellular identity are hallmarks of malignant transformation1-3. As such, the process of acinar-to-ductal metaplasia (ADM) represents a fundamental step in pancreatic ductal adenocarcinoma (PDAC) development, but regulatory pathways controlling ADM are not fully understood4,5. Here, we show that murine pancreatic acinar cells upregulate expression of CASPASE3, CASPASE8, RIPK3 and MLKL - key molecules driving both apoptosis and necroptosis6,7 - during transdifferentiation towards a duct-like phenotype. Spontaneous activation of these respective programmed cell death (PCD) pathways during KRAS-driven transdifferentiation is counterbalanced by transforming growth factor (TGF)-β-activated kinase 1 (TAK1), a kinase transmitting inhibitory phosphorylation signals towards the apoptosis- and necroptosis activator RIPK18. Genetic deletion or pharmacological inhibition of TAK1 simultaneously triggered apoptosis and necroptosis and thereby prevented KRAS-driven ADM in vitro as well as KRAS-driven PDAC in vivo. In line, TAK1 expression is upregulated in human PDAC cells, and pharmacological inhibition of TAK1 triggered PCD in organoid and spheroid cells derived from PDAC patients. Collectively, these findings suggest that TAK1 defines a decision point between ADM and PCD in pancreas cells and represents a promising pharmacological target for the prevention and treatment of PDAC patients.
Project description:The microbial loop is the conventional model by which nutrients and minerals are recycled in aquatic eco-systems. Biochemical pathways in different organisms become metabolically inter-connected such that nutrients are utilized, processed, released and re-utilized by others. The result is that unrelated individuals end up impacting each others’ fitness directly through their metabolic activities. This study focused on the impact of programmed cell death (PCD) on a population’s growth as well as its role in the exchange of carbon between two naturally co-occurring halophilic organisms. Flow cytometric, biochemical, 14C radioisotope tracing assays, and global transcriptomic analyses show that organic algal photosynthate released by Dunalliela salina cells undergoing PCD complements the nutritional needs of other non-PCD D. salina cells. This occurs in vitro in a carbon limited environment and enhances the growth of the population. In addition, a co-occurring heterotroph Halobacterium salinarum re-mineralizes the carbon providing elemental nutrients for the mixoheterotrophic chlorophyte. The significance of this is uncertain and the archaeon can also subsist entirely on the lysate of apoptotic algae. PCD is now well established in unicellular organisms; however its ecological relevance has been difficult to decipher. In this study we found that PCD in D. salina causes the release of organic nutrients such as glycerol, which can be used by others in the population as well as a co-occurring halophilic archaeon. H. salinarum also re-mineralizes the dissolved material promoting algal growth. PCD in D. salina was the mechanism for the flow of dissolved photosynthate between unrelated organisms. Ironically, programmed death plays a central role in an organism’s own population growth and in the exchange of nutrients in the microbial loop. Halobacterium NRC-1 was grown to mid-logarithmic phase (OD600 ~0.4 – 0.8) in MM2. Cells were harvested and washed in MM1 and incubated in MM1 (control) or in Dunaliella harvested supernatant. Cells were harvested at time zero, 5, 10, 20, 40, 80, 160 minutes. RNA from two biological replicate time courses were prepared, averages of these replicates are reported in the published study. The zero time point was harvested immediately after incubation Halobacteria-NRC1 in MM1 or in Dunaliella salina's supernatant.
Project description:The microbial loop is the conventional model by which nutrients and minerals are recycled in aquatic eco-systems. Biochemical pathways in different organisms become metabolically inter-connected such that nutrients are utilized, processed, released and re-utilized by others. The result is that unrelated individuals end up impacting each others’ fitness directly through their metabolic activities. This study focused on the impact of programmed cell death (PCD) on a population’s growth as well as its role in the exchange of carbon between two naturally co-occurring halophilic organisms. Flow cytometric, biochemical, 14C radioisotope tracing assays, and global transcriptomic analyses show that organic algal photosynthate released by Dunalliela salina cells undergoing PCD complements the nutritional needs of other non-PCD D. salina cells. This occurs in vitro in a carbon limited environment and enhances the growth of the population. In addition, a co-occurring heterotroph Halobacterium salinarum re-mineralizes the carbon providing elemental nutrients for the mixoheterotrophic chlorophyte. The significance of this is uncertain and the archaeon can also subsist entirely on the lysate of apoptotic algae. PCD is now well established in unicellular organisms; however its ecological relevance has been difficult to decipher. In this study we found that PCD in D. salina causes the release of organic nutrients such as glycerol, which can be used by others in the population as well as a co-occurring halophilic archaeon. H. salinarum also re-mineralizes the dissolved material promoting algal growth. PCD in D. salina was the mechanism for the flow of dissolved photosynthate between unrelated organisms. Ironically, programmed death plays a central role in an organism’s own population growth and in the exchange of nutrients in the microbial loop.
Project description:Overexpression of programmed cell death 5 gene (PDCD5) in tumor cells enhances apoptosis triggered by growth factor or serum deprivation, and overexpression of its homolog, OsPDCD5, induces the early death of transgenic plants. In this work, a system of inducible OsPDCD5 expression using a heat shock promoter was developed to study PCD in rice at different developmental stages.The results showed that in three-leaf aged and older seedlings, OsPDCD5 could independently induce PCD. In altered plants, OsPDCD5 expression caused lesion mimic phenotype, abnormal leaf morphology, nuclear condensation, DNA fragmentation, and H2O2 production. But two-leaf aged and younger seedlings seedlings showed no visibly morphological phenotype after OsPDCD5 expression, suggested that young seedlings possessed some mechanism inhibiting OsPDCD5 induced PCD. The transcripts of 24-day-old transgenic Zhonghua 11 seedlings heat-shocked for 6 h (before the appearance of PCD phenotypes) were compared with untreated seedlings using microarray analysis (3-Leaf Group) to study the genes involved in OsPDCD5 induced PCD. The experiment was also performed using 18-day-old seedlings to discover why OsPDCD5 expression did not induce PCD in very young seedlings (2-Leaf Group). RNA samples were extracted using TRIzol (Invitrogen) as described by the manufacturer. Microarray analyses were carried out using a competitive hybridization method using the Agilent microarray system. All procedures were carried out according to the manufacturer's protocols. Briefly, total RNA from each sample was used to synthesize cRNA and was labeled with cyanine-5 (Cy5)- or cyanine-3 (Cy3)-labeled CTP. The labeled cRNAs (including a heat-shocked and a control sample) were competitively hybridized to the Agilent Rice Oligo Microarrays, and then washed. The hybridized slides were scanned using Agilent DNA Microarray Scanner and data points were extracted using Agilent Feature Extraction software. Two comparisons were made between biologically independent samples.
Project description:In plants, effector-triggered immunity (ETI) is often associated with programmed cell death (PCD). Although the intracellular immune receptors involved in ETI have been studied extensively, how their activation leads to PCD and disease resistance is poorly understood. We found that the Arabidopsis nuclear envelope protein, CPR5 (constitutive expresser of PR genes 5), plays a crucial role in controlling cell fate in response to stress, as the cpr5 mutant exhibits spontaneous cell death and heightened immunity. A genetic screen revealed that the Cip/Kip CKIs (cyclin-dependent kinase inhibitors), SIM (siamese) and SMR1 (siamese-related 1), are essential for CPR5 signaling, as the sim smr1 double mutant fully suppressed the cpr5 phenotype. More significantly, PCD and ETI are compromised in sim smr1 even with the wild-type CPR5.
Project description:Overexpression of programmed cell death 5 gene (PDCD5) in tumor cells enhances apoptosis triggered by growth factor or serum deprivation, and overexpression of its homolog, OsPDCD5, induces the early death of transgenic plants. In this work, a system of inducible OsPDCD5 expression using a heat shock promoter was developed to study PCD in rice at different developmental stages.The results showed that in three-leaf aged and older seedlings, OsPDCD5 could independently induce PCD. In altered plants, OsPDCD5 expression caused lesion mimic phenotype, abnormal leaf morphology, nuclear condensation, DNA fragmentation, and H2O2 production. But two-leaf aged and younger seedlings seedlings showed no visibly morphological phenotype after OsPDCD5 expression, suggested that young seedlings possessed some mechanism inhibiting OsPDCD5 induced PCD.
Project description:Despite the critical role of programmed cell death (PCD) in plant development and defence responses, its regulation is not fully understood. It has been proposed that mitochondria may control the early stages of plant PCD, but the details of this regulation are currently unknown. Here, we used Arabidopsis thaliana cell suspension culture, a model system that enables induction and precise monitoring of PCD rates, as well as chemical manipulation of this process to generate a quantitative profile of the alterations in mitochondrial and cytosolic proteomes associated with early stages of plant PCD induced by heat stress. The cells were subjected to PCD-inducing heat levels (10 min, 54oC), with/without the calcium channel inhibitor and PCD blocker LaCl3. The stress treatment was followed by separation of cytosolic and mitochondrial fractions and mass spectrometry-based proteome analysis. Heat stress induced rapid and extensive changes in protein abundance in both fractions and 113 mitochondrial proteins were detected in the cytosol upon PCD induction. Western blot analysis confirmed the release of mitochondrial heat shock protein 60 family members occurring in response to PCD-inducing, but not sublethal level of heat stress, that may indicate their cytosolic role as positive regulators of PCD in plants. In our system, LaCl3 appeared to act downstream of cell death initiation signal, as it did not affect the release of mitochondrial proteins, but instead partially inhibited changes occurring in the cytosolic fraction, including upregulation of proteins with hydrolytic activity. Collectively, these generated data provide new insights into the regulation of cell death and survival decisions in plant cells.
Project description:Arabidopsis thaliana cell suspension cultures (ACSC) were subjected to 30-min, mild chemical treatments with three different singlet oxygen elicitors at low-medium light conditions (150 µE m–2 s–1) with the aim of getting a better understanding of singlet oxygen-mediated defence responses in plants. The three elicitors Indigo Carmine (IC), Methylene Violet (MV) and Rose Bengal (RB) at a concentration of 0.5 µM were chosen because they exhibited different abilities to permeate the plasma membrane and to accumulate in the cell soma or organelles such as chloroplasts. In addition, ACSC were treated with 500 µM H2O2 for comparison. Confocal image analysis of Arabidopsis cells revealed that IC was not retained in cells, whereas MV and RB permeated the plasma membrane and accumulated in the chloroplast envelope and inside chloroplasts, respectively. As a consequence of their different cellular location, the physiological, transcriptional and photosynthetic responses of Arabidopsis cells to singlet oxygen production varied from each other and the activation of programmed cell death (PCD) was observed in ACSC treated with 0.5 µM RB, but not with the other elicitor nor with 500 µM H2O2. The role of chloroplasts in the activation of PCD was further investigated when this physiological response was analyzed in dark-grown cell cultures containing undifferentiated plastids. Interestingly, PCD was only activated in light-grown, but not in dark-grown, Arabidopsis cell cultures, suggesting that singlet oxygen-mediated defence responses were initiated inside chloroplasts. Genome-wide transcriptional profile analyses were performed as well and the results proved that there were only statistically significant changes in the transcript expression of light-grown ACSC treated with 0.5 µM RB and 500 µM H2O2, but not with IC nor with MV. Functional enrichment analyses revealed that GO/Biological process terms associated with defence responses were common in the treatments with 0.5 µM RB and 500 µM H2O2; however, resistance response to pathogen and PCD terms were only significantly over-represented in the RB treatment. Moreover, the analysis of the up-regulated transcripts in ACSC treated with 0.5 µM RB brought out that both specific markers for singlet oxygen from the conditional fluorescence (flu) mutant of Arabidopsis and transcripts with a key role in hormone-activated PCD (i.e. ethylene and jasmonic acid) were present, although there was no evidence for the up-regulation of EDS1 encoding the ENHANCED DISEASE SUSCEPTIBILITY PROTEIN 1. Finally, a co-regulation analysis proved that ACSC treated with 0.5 µM RB exhibited higher correlation with the flu family mutants than with other singlet oxygen producer mutants of Arabidopsis or wild-type plants of Arabidopsis subjected to high light treatments, where singlet oxygen was produced in photosystem II and an acclimatory response was activated instead of PCD. 18 Samples total. Six Samples are controls, 3 Samples each treated with Rose Bengal, Hydrogen Peroxide, Methyl Violet, and Indigo Carmine.