Project description:We performed the polysome profiling sequencing in nine arabidopsis tissues across its life cycle to reveal the correlations of translation efficiency to RNA modifications.
Project description:We examined the possible effects of hypertonic stress on Arabidopsis translatome using polysome profiling. We found that the translatome is partly and rapidly reprogrammed in response to hypertonic stress, and such translatome reprogramming is DCP5-dependent.
Project description:Translational control is a key regulatory step in the expression of genes as proteins. In plant cells, translational efficiency of mRNAs differs on different mRNA species, and the efficiency dynamically changes in various conditions. To gain a global view of translational control throughout growth and development, we performed genome-wide analysis of polysome association of mRNA over growth and leaf development in Arabidopsis thaliana by applying the mRNAs in polysome to DNA microarray. This analysis revealed that the degree of polysome association of mRNA had different levels depending on mRNA species, and the polysome association changed greatly throughout growth and development for each. In the growth stage, transcripts showed varying changes in polysome association from strongly depressed to unchanged degree, with the majority of transcripts showing dissociation from ribosomes. On the other hand, during leaf development, the polysome association of transcripts showed a normal distribution from repressed to activated mRNAs when comparing between expanding and expanded leaves. In addition, functional category analysis of the microarray data suggested that translational control has a physiological significance in plant growth and development process, especially in category of signaling and protein synthesis. Besides this, we compared changes in polysome association of mRNAs between various conditions and characterized translational controls in each. This result suggested that mRNAs translation might be controlled by complicated mechanisms for response to each condition. Our results highlight the importance of dynamic changes in mRNA translation in plant development and growth.
Project description:Microarray comparisons of polysome loading in wild-type Arabidopsis and eif3h mutant Goal: To find the target mRNAs that are translationally regulated by eIF3h. BACKGROUND: The eukaryotic translation initiation factor eIF3 has multiple roles during the initiation of translation of cytoplasmic mRNAs. However, the contributions of individual subunits of eIF3 to the translation of specific mRNAs remain poorly understood. RESULTS: Working with stable reporter transgenes in Arabidopsis thaliana it was demonstrated that the h subunit of eIF3 contributes to the efficient translation initiation of mRNAs harboring upstream open reading frames (uORFs) in their 5’ leader sequence. uORFs, which can function as devices for translational regulation, are present in over 30% of Arabidopsis mRNAs, and are enriched among mRNAs for transcriptional regulators and protein modifying enzymes. Microarray comparisons of polysome loading in wild-type and eif3h mutant plants revealed that eIF3h generally helps to maintain efficient polysome loading of mRNAs harboring multiple uORFs. Independently, eIF3h also boosted polysome loading of mRNAs with long coding sequences. Moreover, the lesion in eIF3h revealed a concerted upregulation of translation for specific functional subgroups of mRNAs, including ribosomal proteins and proteins involved in photosynthesis. CONCLUSIONS: The intact eIF3h protein contributes to efficient translation initiation on 5’ leader sequences harboring multiple uORFs, although mRNA features independent of uORFs were also implicated. Moreover, our data suggest that regulons of translational control can be revealed by mutations in generic translation initiation factors. Keywords: mutant, polysome, non-polysome
Project description:To understand the contribution of the k subunit of eukaryotic transcription factor 3 (eif3k) to the translation of specific mRNAs, we compared the polysome loading states and overall transcript levels of wild type Arabidopsis and the eif3k T-DNA insertion mutant by Affymetrix arrays. We analyzed the polysome loading states of wild type Arabidopsis and the eif3k mutant using the Arabidopsis Affymetrix ATH1 array. Data from 3 biological replicates were collected.
Project description:To understand the role of GCN2 in regulating translation, we compared the polysome loading state and overall transcript level between Arabidopsis thaliana wild type (ecotype Landsberg erecta) and gcn2 (Genetrap line GT8359, Cold Spring Harbor Laboratory) seedlings with or without herbicide chlorosufuron treatment RNA was fractionated using sucrose gradients into polysomal and nonpolysomal RNAs. We also determined overall total transcript levels. We used Affymetrix ATH1 microarrays.