We used the flu mutant of Arabidopsis and a transgenic line that overexpresses the thylakoid-bound ascorbate peroxidase (tAPX) to address the interactions between different reactive oxygen species (ROS) signaling pathways. The conditional flu mutant of Arabidopsis accumulates excess protochlorophyllide in the dark within chloroplast membranes that upon illumination acts as a photosensitizer and generates singlet oxygen (1O2). Immediately after the release of singlet oxygen rapid changes in nuclear gene expression occur. Distinct sets of genes were activated that were different from those induced by other reactive oxygen species, superoxide or hydrogen peroxide (H2O2), suggesting that different types of active oxygen species activate distinct signaling pathways. It was not known whether the pathways operate separately or interact with each other. We have addressed this problem by modulating noninvasively the level of H2O2 in plastids by means of a transgenic line that overexpresses the thylakoid-bound ascorbate peroxidase (tAPX, line 14/2 PMID: 15165186). In the flu mutant overexpressing tAPX, the expression of most of the nuclear genes that were rapidly activated after the release of 1O2 was significantly higher in flu plants overexpressing tAPX, whereas in wild-type plants, overexpression of tAPX had only a very minor impact on nuclear gene expression. The results suggest that H2O2 antagonizes the 1O2-mediated signaling of stress responses as seen in the flu mutant. This cross-talk between H2O2- and 1O2-dependent signaling pathways might contribute to the overall stability and robustness of wild-type plants exposed to adverse environmental stress conditions.
Cross-talk between singlet oxygen- and hydrogen peroxide-dependent signaling of stress responses in Arabidopsis thaliana.
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View SamplesThe myogenic regulatory factor MRF4 is expressed at high levels in myofibers of adult skeletal muscle, but its function is unknown. Here we show that knockdown of MRF4 in adult muscle causes hypertrophy and prevents denervation-induced atrophy. This effect is accompanied by increased protein synthesis and the widespread activation of genes involved in muscle contraction, excitation-contraction coupling and energy metabolism, many of which are known targets of MEF2 transcription factors. Genes regulated by MEF2 represent the top-ranking gene set enriched after Mrf4 RNAi, and a MEF2 reporter is inhibited by co-transfected MRF4 and activated by Mrf4 RNAi. The role of MEF2 in mediating the effect of MRF4 knockdown is supported by the finding that Mrf4 RNAi-dependent increase in fiber size is prevented by dominant negative MEF2, while constitutively active MEF2 is able to induce myofiber hypertrophy. The nuclear localization of the MEF2 co-repressor HDAC4 is impaired by Mrf4 knockdown, suggesting that MRF4 acts by stabilizing a repressor complex that controls MEF2 activity. The demonstration that fiber size in adult skeletal muscle is controlled by the MRF4-MEF2 axis opens new perspectives in the search for therapeutic targets to prevent muscle wasting, in particular sarcopenia and cachexia.
MRF4 negatively regulates adult skeletal muscle growth by repressing MEF2 activity.
Specimen part
View SamplesRecent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells and tumour initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-kB pathway can drive dedifferentiation of intestinal cells lacking Apc.
TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis.
Specimen part
View SamplesRecent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells and tumour initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-kB pathway can drive dedifferentiation of intestinal cells lacking Apc.
TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis.
No sample metadata fields
View SamplesWe report the application of low cell number sequencing of identifiable Drosophila melanogaster neurons following behavior. We demonstate the feasibility of identifying the transcriptome of 5 Mushroom Body output Neurons and 2 classes of Kenyon Cells. We find these neurons display a diverse repertoire of receptors and signaling transcripts. This information alone seems to be enough to identify each class of neurons in the study. In additional we show that aversive long-term memory induces changes in gene transcript levels in a subset of these neurons. This study provides a framework for identifying neuronal classes in Drosophila melanogaster and gaining insight into the interplay between behavior and gene regulation. Overall design: 5 Mushroom Body output neurons and 2 classes of kenyon cells are used to look at general gene expression and changes following aversive long term memory. Paired control and trained animals were used and a minimum of 4 pairs up to 6 pairs. Animals were of the same background (w1118). Animals were aged and parental matched. Cells were harvested at the same chronological time for the animals across all experiments. All animals were exposed to 1 minute of each odor and 1 minute of a series of 12 5second 60V shocks. This was considered one block and then the animals had spaced training of each block so there was a 10 minute break between 8 blocks of training. Trained animals had an odor paired with a shock, control animals received the shock then the odor stimulus. All cells were harvested usign a patch pipet from living animals on an electrophysiology rig within a half hour of the end of training. Cells were amplified using the Clontech SMARTer Ultra Low Input RNA version 2 High Volume kit. 2 Brain samples were also collected and 3-4 whole fly samples for each genotype were collected to account for background differences across flies.
Cell-Type-Specific Transcriptome Analysis in the Drosophila Mushroom Body Reveals Memory-Related Changes in Gene Expression.
Subject
View SamplesThis experiment tests the hypothesis that interleukin-1 promotes SMC phenotypic modulation to a distinct inflammatory state relative to the growth factor PDGF-DD.
Interleukin-1β modulates smooth muscle cell phenotype to a distinct inflammatory state relative to PDGF-DD via NF-κB-dependent mechanisms.
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View SamplesBcl11a is a transcription factor known to regulate lymphoid and erythroid development. Recent bioinformatic analysis of global gene expression patterns has suggested a role for Bcl11a in the development of dendritic cell (DC) lineages. We tested this hypothesis by analyzing the development of DC and other lineages in Bcl11a(-/-) mice. We show that Bcl11a is required for expression of IL-7 receptor (IL-7R) and Flt3 in early hematopoietic progenitor cells. The loss of IL-7R(+) common lymphoid progenitors accounts for previously described lymphoid defects in Bcl11a(-/-) mice. In addition, we found severely decreased numbers of plasmacytoid dendritic cells (pDCs) in Bcl11a(-/-) fetal livers and in the bone marrow of Bcl11a(-/-) fetal liver chimeras. Moreover, Bcl11a(-/-) cells show severely impaired in vitro development of Flt3L-derived pDCs and classical DCs (cDCs). In contrast, we found normal in vitro development of DCs from Bcl11a(-/-) fetal liver cells treated with GM-CSF. These results suggest that the persistent cDC development observed in Bcl11a(-/-) fetal liver chimeras reflects derivation from a Bcl11a- and Flt3-independent pathway in vivo.
Bcl11a controls Flt3 expression in early hematopoietic progenitors and is required for pDC development in vivo.
Specimen part
View SamplesThe present study reveals LMYC and MXD1 as novel regulators of a transcriptional program that is modulated during the maturation of Batf3-dependent dendritic cells (also known as type I classical dendritic cells or cDC1s).
The MYCL and MXD1 transcription factors regulate the fitness of murine dendritic cells.
Specimen part
View SamplesES cells differentiated in the presence of the Wnt inhibitor DKK1 fail to express the transcription factor Snail and undergo EMT or mesoderm differentiation. We generated an ES cell line, A2.snail, that induced Snail expression upon addition of doxycycline addition.
Snail promotes the cell-autonomous generation of Flk1(+) endothelial cells through the repression of the microRNA-200 family.
Specimen part, Cell line
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Zbtb46 expression distinguishes classical dendritic cells and their committed progenitors from other immune lineages.
Specimen part
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