Different Patterns of mRNA Nuclear Retention during Meiotic Prophase in Larch Microsporocytes

Recent studies show a crucial role of post-transcriptional processes in the regulation of gene expression. Our research has shown that mRNA retention in the nucleus plays a significant role in such regulation. We studied larch microsporocytes during meiotic prophase, characterized by pulsatile transcriptional activity. After each pulse, the transcriptional activity is silenced, but the transcripts synthesized at this time are not exported immediately to the cytoplasm but are retained in the cell nucleus and especially in Cajal bodies, where non-fully-spliced transcripts with retained introns are accumulated. Analysis of the transcriptome of these cells and detailed analysis of the nuclear retention and transport dynamics of several mRNAs revealed two main patterns of nuclear accumulation and transport. The majority of studied transcripts followed the first one, consisting of a more extended retention period and slow release to the cytoplasm. We have shown this in detail for the pre-mRNA and mRNA encoding RNA pol II subunit 10. In this pre-mRNA, a second (retained) intron is posttranscriptionally spliced at a precisely defined time. Fully mature mRNA is then released into the cytoplasm, where the RNA pol II complexes are produced. These proteins are necessary for transcription in the next pulse to occur.mRNAs encoding translation factors and SERRATE followed the second pattern, in which the retention period was shorter and transcripts were rapidly transferred to the cytoplasm. The presence of such a mechanism in various cell types from a diverse range of organisms suggests that it is an evolutionarily conserved mechanism of gene regulation.

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In situ dissection of domain boundaries affect genome topology and gene transcription in Drosophila

10.1101/776542 ◽

2019 ◽

Author(s):

Rodrigo G. Arzate-Mejía ◽

Angel Josué Cerecedo-Castillo ◽

Georgina Guerrero ◽

Mayra Furlan-Magaril ◽

Félix Recillas-Targa

Keyword(s):

Gene Expression ◽

Molecular Mechanisms ◽

Regulation Of Gene Expression ◽

Topological Defects ◽

Rna Pol Ii ◽

Pol Ii ◽

Domain Boundaries ◽

Topologically Associated Domains ◽

Genetic Sequences

AbstractThe molecular mechanisms responsible for Topologically Associated Domains (TADs) formation are not yet fully understood. In Drosophila, it has been proposed that transcription is fundamental for TAD organization while the participation of genetic sequences bound by Architectural Proteins (APs) remains controversial. Here, we investigate the contribution of domain boundaries to TAD organization and the regulation of gene expression at the Notch gene locus in Drosophila. We find that deletion of domain boundaries results in TAD fusion and long-range topological defects that are accompanied by loss of APs and RNA Pol II chromatin binding as well as defects in transcription. Together, our results provide compelling evidence on the contribution of discrete genetic sequences bound by APs and RNA Pol II in the partition of the genome into TADs and in the regulation of gene expression in Drosophila.

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Tumor Suppressor Pten Inhibits Nuclear Accumulation of β-Catenin and T Cell/Lymphoid Enhancer Factor 1–Mediated Transcriptional Activation

The Journal of Cell Biology ◽

10.1083/jcb.153.6.1161 ◽

2001 ◽

Vol 153 (6) ◽

pp. 1161-1174 ◽

Cited By ~ 175

Author(s):

Sujata Persad ◽

Armelle A.Troussard ◽

Timothy R. McPhee ◽

David J. Mulholland ◽

Shoukat Dedhar

Keyword(s):

T Cell ◽

Tumor Suppressor ◽

Transcriptional Activation ◽

Transcriptional Activity ◽

Glycogen Synthase ◽

Regulation Of Gene Expression ◽

Nuclear Accumulation ◽

Luciferase Reporter ◽

Independent Manner ◽

Elevated Expression

β-Catenin is a protein that plays a role in intercellular adhesion as well as in the regulation of gene expression. The latter role of β-catenin is associated with its oncogenic properties due to the loss of expression or inactivation of the tumor suppressor adenomatous polyposis coli (APC) or mutations in β-catenin itself. We now demonstrate that another tumor suppressor, PTEN, is also involved in the regulation of nuclear β-catenin accumulation and T cell factor (TCF) transcriptional activation in an APC-independent manner. We show that nuclear β-catenin expression is constitutively elevated in PTEN null cells and this elevated expression is reduced upon reexpression of PTEN. TCF promoter/luciferase reporter assays and gel mobility shift analysis demonstrate that PTEN also suppresses TCF transcriptional activity. Furthermore, the constitutively elevated expression of cyclin D1, a β-catenin/TCF–regulated gene, is also suppressed upon reexpression of PTEN. Mechanistically, PTEN increases the phosphorylation of β-catenin and enhances its rate of degradation. We define a pathway that involves mainly integrin-linked kinase and glycogen synthase kinase 3 in the PTEN-dependent regulation of β-catenin stability, nuclear β-catenin expression, and transcriptional activity. Our data indicate that β-catenin/TCF–mediated gene transcription is regulated by PTEN, and this may represent a key mechanism by which PTEN suppresses tumor progression.

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Selective Requirement for SAGA in Hog1-Mediated Gene Expression Depending on the Severity of the External Osmostress Conditions

Molecular and Cellular Biology ◽

10.1128/mcb.00089-07 ◽

2007 ◽

Vol 27 (11) ◽

pp. 3900-3910 ◽

Cited By ~ 68

Author(s):

Meritxell Zapater ◽

Marc Sohrmann ◽

Matthias Peter ◽

Francesc Posas ◽

Eulàlia de Nadal

Keyword(s):

Gene Expression ◽

Rna Polymerase Ii ◽

Genetic Screening ◽

Essential Role ◽

Regulation Of Gene Expression ◽

Transcriptional Program ◽

Rna Pol Ii ◽

Pol Ii ◽

Genome Wide ◽

Transcriptional Complex

ABSTRACT Regulation of gene expression by the Hog1 stress-activated protein kinase is essential for proper cell adaptation to osmostress. Hog1 coordinates an extensive transcriptional program through the modulation of transcription. To identify systematically novel components of the transcriptional machinery required for osmostress-mediated gene expression, we performed an exhaustive genome-wide genetic screening, searching for mutations that render cells osmosensitive at high osmolarity and that are associated with reduced expression of osmoresponsive genes. The SAGA and Mediator complexes were identified as putative novel regulators of osmostress-mediated transcription. Interestingly, whereas Mediator is essential for osmostress gene expression, the requirement for SAGA is different depending on the strength of the extracellular osmotic conditions. At mild osmolarity, SAGA mutants show only very slight defects on RNA polymerase II (Pol II) recruitment and gene expression, whereas at severe osmotic conditions, SAGA mutants show completely impaired RNA Pol II recruitment and transcription of osmoresponsive genes. Thus, our results define an essential role for Mediator in osmostress gene expression and a selective role for SAGA under severe osmostress. Our results indicate that the requirement for a transcriptional complex to regulate a promoter might be determined by the strength of the stimuli perceived by the cell through the regulation of interactions between transcriptional complexes.

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Novel blocker of NFAT activation inhibits IL-6 production in human myometrial arteries and reduces vascular smooth muscle cell proliferation

AJP Cell Physiology ◽

10.1152/ajpcell.00590.2005 ◽

2007 ◽

Vol 292 (3) ◽

pp. C1167-C1178 ◽

Cited By ~ 67

Author(s):

Lisa M. Nilsson ◽

Zheng-Wu Sun ◽

Jenny Nilsson ◽

Ina Nordström ◽

Yung-Wu Chen ◽

...

Keyword(s):

Cell Proliferation ◽

Protein Synthesis ◽

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Transcriptional Activity ◽

Cell Types ◽

Nuclear Accumulation ◽

Luciferase Reporter ◽

Activated T Cells ◽

Endothelin 1

The calcineurin/nuclear factor of activated T cells (NFAT) signaling pathway has been found to play a role in regulating growth and differentiation in several cell types. However, the functional significance of NFAT in the vasculature is largely unclear. Here we show that NFATc1, NFATc3, and NFATc4 are expressed in human myometrial arteries. Confocal immunofluorescence and Western blot analysis revealed that endothelin-1 efficiently increases NFATc3 nuclear accumulation in native arteries. Endothelin-1 also stimulates NFAT-dependent transcriptional activity, as shown by a luciferase reporter assay. Both the agonist-induced NFAT nuclear accumulation and transcriptional activity were prevented by the calcineurin inhibitor CsA and by the novel NFAT blocker A-285222. Chronic inhibition of NFAT significantly reduced IL-6 production in intact myometrial arteries and inhibited cell proliferation in vascular smooth muscle cells cultured from explants from the same arteries. Furthermore, by using small interfering RNA-mediated reduction of NFATc3, we show that this isoform is involved in the regulation of cell proliferation. Protein synthesis in intact arteries was investigated using autoradiography of [35S]methionine incorporation in serum-free culture. Inhibition of NFAT signaling did not affect overall protein synthesis or specifically the synthesis rates of major proteins associated with the contractile/cytoskeletal system. An intact contractile phenotype under these conditions was also shown by unchanged force response to depolarization or agonist stimulation. Our results demonstrate NFAT expression and activation in native human vessels and point out A-285222 as a powerful pharmacological blocker of NFAT signaling in the vasculature.

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Nuclear retention of pre-mRNA involving Cajal bodies during meiotic prophase in plants

10.1101/2021.04.19.440419 ◽

2021 ◽

Author(s):

Magda Rudzka ◽

Malwina Hyjek-Skladanowska ◽

Patrycja Wroblewska-Ankiewicz ◽

Karolina Majewska ◽

Marcin Golebiewski ◽

...

Keyword(s):

Gene Expression ◽

Gene Regulation ◽

Meiotic Prophase ◽

Gene Expression Regulation ◽

Regulation Of Gene Expression ◽

Cajal Bodies ◽

Nuclear Retention ◽

Retained Introns ◽

Generative Cells ◽

Mature Mrnas

Gene regulation ensures that the appropriate genes are expressed at the proper times. Nuclear retention of incompletely spliced or mature mRNAs emerges as a novel, previously underappreciated layer of post-transcriptional gene regulation. Studies on this phenomenon indicated that it exerted significant impact on the regulation of gene expression by regulating export and translation delay, which allows synthesis of specific proteins in response to a stimulus, e.g. under stress conditions or at strictly controlled time points, e.g. during cell differentiation or development. Here, we found that transcription in microsporocytes, during prophase of the first meiotic division, occurs in pulsatile manner. After each pulse, the transcriptional activity is silenced, but the transcripts synthesized at this time are not exported immediately to the cytoplasm, but are retained in the nucleoplasm and Cajal bodies (CBs). In contrast to nucleoplasm, mature transcripts were not found in CBs. Only non-fully-spliced transcripts with retained introns were stored in the CBs. Retained introns are spliced at precisely defined times, and fully mature mRNAs are released into the cytoplasm, where the proteins are produced. These proteins are necessary for further cell development during meiotic prophase. Our findings provide new insight into the regulatory mechanisms of gene expression based on mRNA retention in the nucleus during the development of generative cells in plants. Similar processes were observed during spermatogenesis in animals. This indicates the existence of an evolutionarily conserved mechanism of gene expression regulation during generative cells development in Eukaryota.

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