Early gibberellin responses and DELLA protein direct targets in Arabidopsis
Ontology highlight
ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
PROVIDER: GSE8785 | GEO | 2007/11/21
SECONDARY ACCESSION(S): PRJNA102081
REPOSITORIES: GEO
Similar Datasets
Project description:This SuperSeries is composed of the following subset Series:; GSE8739: Early gibberellin responses in Arabidopsis; GSE8741: DELLA protein direct targets in Arabidopsis Experiment Overall Design: Refer to individual Series
2008-06-16 | E-GEOD-8785 | biostudies-arrayexpress
Project description:The aim of this study is to identify early DELLA protein-responsive genes using a Dexamethasone (DEX)-inducible system. Two transgenic lines were used: one induces the expression of a dominant, gibberellin non-responsive DELLA protein (rga-delta17); the other is a control line that carries the same vector, but lacks the rga-delta17 transgene. By comparing the gene expression changes in the line that expresses the rga-delta17 protein in the presence or absence of DEX it is possible to identify putative targets of DELLA proteins. An empty vector transgenic line was included in this study to identify genes that might be regulated by the DEX inducible system that are not dependent on the DELLA protein. Keywords: Dexamethasone treatment, gibberellin treatment, time course, transgene effect
2007-11-21 | GSE8741 | GEO
Project description:The aim of this study is to identify early DELLA protein-responsive genes using a Dexamethasone (DEX)-inducible system. Two transgenic lines were used: one induces the expression of a dominant, gibberellin non-responsive DELLA protein (rga-delta17); the other is a control line that carries the same vector, but lacks the rga-delta17 transgene. By comparing the gene expression changes in the line that expresses the rga-delta17 protein in the presence or absence of DEX it is possible to identify putative targets of DELLA proteins. An empty vector transgenic line was included in this study to identify genes that might be regulated by the DEX inducible system that are not dependent on the DELLA protein. Experiment Overall Design: Seedlings of both transgenic lines were pretreated for 16 h with 2 uM GA4 to enhance gibberellin responses. Because DELLA proteins are strong signaling repressors, this pretreatment should maximize the effect of DELLA induction. Eight-day old seedlings were treated with 2 uM GA4 or a combination of 2 uM GA4 plus 10 uM DEX to induce the rga-delta17 transgene. Three biological replicas for the transgenic line that carries the DEX-inducible rga-delta17 transgene were generated at 2h and 4h. For the empty vector line, only 2 biological replicas were generated at 4h of treatment with 2 uM GA with or without 10 uM DEX.
2008-06-16 | E-GEOD-8741 | biostudies-arrayexpress
Project description:The aim is to identify early gibberellin responsive genes in a gibberellin deficient strain such as ga1-3. Such genes are likely regulated by DELLA proteins which are master gibberellin repressors. DELLA proteins are rapidly degraded after gibberellin treatment, but their direct target genes still need to be elucidated. Keywords: hormone response, gibberellin treatment
2007-11-21 | GSE8739 | GEO
Project description:The plant hormone gibberellic acid (GA) is a crucial regulator of growth and development. The main paradigm of GA signaling puts forward transcriptional regulation via the degradation of DELLA transcriptional repressors. GA has also been shown to regulate tropic responses by modulation of the plasma membrane incidence of PIN auxin transporters by an unclear mechanism. Here we uncovered the cellular and molecular mechanisms by which GA redirects protein trafficking and thus regulates cell surface functionality. Photoconvertible reporters revealed that GA balances the protein traffic between the vacuole degradation route and recycling back to the cell surface. Low GA levels promote vacuolar delivery and degradation of multiple cargos, including PIN proteins, whereas high GA levels promote their recycling to the plasma membrane. This GA effect requires components of the retromer complex, such as Sorting Nexin 1 (SNX1) and its interacting, microtubule (MT)-associated protein, the Cytoplasmic Linker-Associated Protein (CLASP1). Accordingly, GA regulates the subcellular distribution of SNX1 and CLASP1, and the intact MT cytoskeleton is essential for the GA effect on trafficking. This GA cellular action occurs through DELLA proteins that regulate the MT and retromer presumably via their interaction partners Prefoldins (PFDs). Our study identified a branching of the GA signaling pathway at the level of DELLA proteins, which, in parallel to regulating transcription, also target by a nontranscriptional mechanism the retromer complex acting at the intersection of the degradation and recycling trafficking routes. By this mechanism, GA can redirect receptors and transporters to the cell surface, thus coregulating multiple processes, including PIN-dependent auxin fluxes during tropic responses.
| S-EPMC5889667 | biostudies-literature
Project description:The plant hormone gibberellin (GA) is crucial for multiple aspects of plant growth and development. To study the relevant regulatory mechanisms, we isolated a rice mutant earlier flowering1, el1, which is deficient in a casein kinase I that has critical roles in both plants and animals. el1 had an enhanced GA response, consistent with the suppression of EL1 expression by exogenous GA(3). Biochemical characterization showed that EL1 specifically phosphorylates the rice DELLA protein SLR1, proving a direct evidence for SLR1 phosphorylation. Overexpression of SLR1 in wild-type plants caused a severe dwarf phenotype, which was significantly suppressed by EL1 deficiency, indicating the negative effect of SLR1 on GA signalling requires the EL1 function. Further studies showed that the phosphorylation of SLR1 is important for maintaining its activity and stability, and mutation of the candidate phosphorylation site of SLR1 results in the altered GA signalling. This study shows EL1 a novel and key regulator of the GA response and provided important clues on casein kinase I activities in GA signalling and plant development.
| S-EPMC2885930 | biostudies-literature
Project description:Gibberellins (GAs) are phytohormones that regulate various developmental processes in plants. The initial GA signalling events involve the binding of a GA to the soluble GA receptor protein GID1, followed by the binding of the complex to the negative transcriptional regulator of GA signaling, the DELLA protein. Although X-ray structures for certain Arabidopsis GID1/GA/DELLA protein complexes have previously been determined, examination of these complexes did not fully clarify how a DELLA protein recognizes and binds to a GID1/GA complex. Herein, we present a study aimed at physically defining, via a combination of gel chromatography, isothermal titration calorimetry (ITC), small-angle X-ray scattering experiments (SAXS), NMR spectroscopy and mutagenesis, how the rice DELLA protein (SLR1) binds to the rice GID1/GA complex. We have identified the shortest SLR1 sequence (M28-A112) that binds the rice GID/GA complex tightly. The binding constant for the ternary complex that includes SLR1(M28-A112) is 2.9 × 107 M-1; the binding is enthalpically driven and does not depend on the chemical nature of the bound GA. Furthermore, the results of SAXS, ITC, and gel filtration experiments indicate that when free in solution, SLR1(M28-A112) is a natively unfolded protein. The NMR experiments expand this observation to show that the unfolded mutant also contains a small amount of marginally stable secondary structure. Conversely, the protein has a highly ordered structure when bound one-to-one to GID1/GA.
| S-EPMC6286387 | biostudies-literature
Project description:The diterpenoid phytohormone gibberellin (GA) controls diverse developmental processes throughout the plant life cycle. DELLA proteins are master growth repressors that function immediately downstream of the GA receptor to inhibit GA signaling. By doing so, DELLAs also play pivotal roles as integrators of internal developmental signals from multiple hormone pathways and external cues. DELLAs are likely nuclear transcriptional regulators, which interact with other transcription factors to modulate expression of GA-responsive genes. DELLAs are also involved in maintaining GA homeostasis through feedback up-regulating expression of GA biosynthesis and receptor genes. However, the molecular mechanisms by which DELLAs restrict growth and development are largely unknown. This study reveals an important step of the mechanism. Previous microarray studies identified scarecrow-like 3 (SCL3) as a direct target gene of DELLA in Arabidopsis seedlings. SCL3 expression is induced by DELLA and repressed by GA. Unexpectedly, a scl3 null mutant displays reduced GA responses and elevated expression of GA biosynthesis genes during seed germination and seedling growth, indicating that SCL3 functions as a positive regulator of GA signaling. SCL3 seems to act as an attenuator of DELLA proteins. Transient expression, ChIP, and co-IP studies show that SCL3 autoregulates its own transcription by directly interacting with DELLA. Our data further show that SCL3 and DELLA antagonize each other in controlling both downstream GA responses and upstream GA biosynthetic genes. This work is beginning to shed light on how this complex regulatory network achieves GA homeostasis and controls GA-mediated growth and development in the plant.
| S-EPMC3033277 | biostudies-literature
Project description:Light and gibberellins (GAs) antagonistically regulate hypocotyl elongation in plants. It has been demonstrated that DELLAs, which are negative regulators of GA signalling, inhibit phytochrome-interacting factors 3 and 4 (PIF3 and PIF4) by sequestering their DNA-recognition domains. However, it is unclear whether there are other mechanisms of regulatory crosstalk between DELLAs and PIFs. Here, we demonstrate that DELLAs negatively regulate the abundance of four PIF proteins through the ubiquitin-proteasome system. Reduction of PIF3 protein abundance by DELLAs correlates closely with reduced hypocotyl elongation. Both sequestration and degradation of PIF3 by DELLAs contribute to a reduction in PIF3 binding to its target genes. Thus, we show that promotion of PIF degradation by DELLAs is required to coordinate light and GA signals, and the dual regulation of transcription factors by DELLAs by both sequestration and degradation may be a general mechanism.
| S-EPMC4906400 | biostudies-literature
Project description:Circadian clock circuitry intersects with a plethora of signaling pathways to adequately time physiological processes to occur at the most appropriate time of the day and year. However, our mechanistic understanding of how the clockwork is wired to its output is limited. Here we uncover mechanistic connections between the core clock component GIGANTEA (GI) and hormone signaling through the modulation of key components of the transduction pathways. Specifically, we show how GI modulates gibberellin (GA) signaling through the stabilization of the DELLA proteins, which act as negative components in the signaling of this hormone. GI function within the GA pathway is required to precisely time the permissive gating of GA sensitivity, thereby determining the phase of GA-regulated physiological outputs.
| S-EPMC6815129 | biostudies-literature