A constant level of Pol III is maintained in the nucleus by nuclear retention and degradation-supplementery
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus Musculus
SUBMITTER: 
Xiong Ji
PROVIDER: PXD042522 | iProX | Mon May 29 00:00:00 BST 2023
REPOSITORIES: iProX
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Project description:RNA Pol III plays a vital role in transcription and as a viral-DNA sensor, but how it is assembled and distributed within cells remain poorly understood. Here, we show that Pol III is assembled with chaperones in the cytoplasm and forms transcription-dependent protein clusters upon transport into the nucleus. The largest subunit (RPC1) depletion through an auxin-inducible degron leads to rapid degradation and disassembly of Pol III complex in the nucleus and cytoplasm, respectively. This generates a pool of partially assembled Pol III intermediates, which can be rapidly mobilized into the nucleus upon the restoration of RPC1. Our study highlights the critical role of subcellular localization in determining Pol III's fate and provide insight into the dynamic regulation of nuclear Pol III levels and the origin of cytoplasmic Pol III complexes involved in mediating viral immunity.
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Project description:RNA polymerase II (Pol II) is the central enzyme that carries out eukaryotic mRNA transcription and consists of a 10-subunit catalytic core and a heterodimeric subcomplex of subunits Rpb4 and Rpb7 (Rpb4/7). Rpb4/7 has been proposed to shuttle from the nucleus to the cytoplasm, and to function there in mRNA translation and degradation. Here we provide evidence that Rpb4 mainly functions in nuclear mRNA synthesis by Pol II, and evidence arguing against an important cytoplasmic role. We used metabolic RNA labeling and comparative Dynamic Transcriptome Analysis (cDTA) to show that Rpb4 deletion in Saccharomyces cerevisiae causes a drastic defect in mRNA synthesis that is compensated by down-regulation of mRNA degradation, resulting in mRNA level buffering. Deletion of Rpb4 can be rescued by covalent fusion of Rpb4 to the Pol II core subunit Rpb2, which largely restores mRNA synthesis and degradation defects caused by Rpb4 deletion. Thus Rpb4 is a bona fide Pol II core subunit which functions mainly in mRNA synthesis.
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Project description:The cytopheno project studies cytoplasmic-nucleus interactions by characterizing cytolines (same nucleus but different cytoplasm, and conversely) at several levels (growth, germination, transcriptomic, proteomic, metabolomic) notably in response to nitrogen deficiency. For this project, there are 48 hybridizations performed as following, on leaf samples from hydroponically grown plants. bioadapt2011_cytopheno - bioadapt2011_cytopheno - Evaluation of the impact of nucleo-cytoplasmic co-adaptation disruptions on nuclear genome expression in Arabidopsis - Obtaining samples by hydroponic culture.
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Project description:tRNAs are transcribed and partially processed in the nucleus before they are exported to the cytoplasm where they have an essential role in protein synthesis. Surprisingly, mature cytoplasmic tRNAs shuttle between nucleus and cytoplasm and its distribution is nutrient-dependent. At least three members of M-NM-2-importin family, Los1, Mtr10, and Msn5, function in tRNA nuclear-cytoplasmic intracellular movement. To test the hypothesis that the tRNA retrograde pathway regulates translation of particular transcripts We compared individual translation activity index (P/NP), obtained from the ratio of polysome-associated (P) to not associated (non-polysomal, NP) mRNAs, in the msn5M-NM-^T, mtr10M-NM-^T, and wild-type cells under fed or acute amino acid depletion conditions Polysome associated (P), not associated (non-polysomal, NP), and total (T) RNAs were isolated from yeast cells, including wild-type (BY4742), msn5 deletion, mtr10 deletion, grown in fed and 30-min amino acid starvation conditions
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