Shade-induced nuclear localization of PIF7 is regulated by phosphorylation and 14-3-3 proteins in Arabidopsis

Shade avoidance syndrome enables shaded plants to grow and compete effectively against their neighbors. In Arabidopsis, the shade-induced de-phosphorylation of the transcription factor PIF7 (PHYTOCHROME-INTERACTING FACTOR 7) is the key event linking light perception to stem elongation. However, the mechanism through which phosphorylation regulates the activity of PIF7 is unclear. Here, we show that shade light induces the de-phosphorylation and nuclear accumulation of PIF7. Phosphorylation-resistant site mutations in PIF7 result in increased nuclear localization and shade-induced gene expression, and consequently augment hypocotyl elongation. PIF7 interacts with 14-3-3 proteins. Blocking the interaction between PIF7 and 14-3-3 proteins or reducing the expression of 14-3-3 proteins accelerates shade-induced nuclear localization and de-phosphorylation of PIF7, and enhances the shade phenotype. By contrast, the 14-3-3 overexpressing line displays an attenuated shade phenotype. These studies demonstrate a phosphorylation-dependent translocation of PIF7 when plants are in shade and a novel mechanism involving 14-3-3 proteins, mediated by the retention of PIF7 in the cytoplasm that suppresses the shade response.

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Multiple Nuclear Localization Signals Mediate Nuclear Localization of the GATA Transcription Factor AreA

Eukaryotic Cell ◽

10.1128/ec.00040-14 ◽

2014 ◽

Vol 13 (4) ◽

pp. 527-538 ◽

Cited By ~ 18

Author(s):

Cameron C. Hunter ◽

Kendra S. Siebert ◽

Damien J. Downes ◽

Koon Ho Wong ◽

Sara D. Kreutzberger ◽

...

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Dna Binding ◽

Nuclear Localization ◽

Fluorescent Protein ◽

Nitrogen Sources ◽

Nuclear Accumulation ◽

Content Type ◽

Nuclear Localization Signals ◽

Gata Transcription Factor

ABSTRACTTheAspergillus nidulansGATA transcription factor AreA activates transcription of nitrogen metabolic genes in response to nitrogen limitation and is known to accumulate in the nucleus during nitrogen starvation. Sequence analysis of AreA revealed multiple nuclear localization signals (NLSs), five putative classical NLSs conserved in fungal AreA orthologs but not in theSaccharomyces cerevisiaefunctional orthologs Gln3p and Gat1p, and one putative noncanonical RRX33RXR bipartite NLS within the DNA-binding domain. In order to identify the functional NLSs in AreA, we constructedareAmutants with mutations in individual putative NLSs or combinations of putative NLSs and strains expressing green fluorescent protein (GFP)-AreA NLS fusion genes. Deletion of all five classical NLSs individually or collectively did not affect utilization of nitrogen sources or AreA-dependent gene expression and did not prevent AreA nuclear localization. Mutation of the bipartite NLS conferred the inability to utilize alternative nitrogen sources and abolished AreA-dependent gene expression likely due to effects on DNA binding but did not prevent AreA nuclear localization. Mutation of all six NLSs simultaneously prevented AreA nuclear accumulation. The bipartite NLS alone strongly directed GFP to the nucleus, whereas the classical NLSs collaborated to direct GFP to the nucleus. Therefore, AreA contains multiple conserved NLSs, which show redundancy and together function to mediate nuclear import. The noncanonical bipartite NLS is conserved in GATA factors fromAspergillus, yeast, and mammals, indicating an ancient origin.

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Xenopus nuclear factor 7 (xnf7) possesses an NLS that functions efficiently in both oocytes and embryos

Journal of Cell Science ◽

10.1242/jcs.105.2.389 ◽

1993 ◽

Vol 105 (2) ◽

pp. 389-395

Author(s):

X. Li ◽

L.D. Etkin

Keyword(s):

Transcription Factor ◽

Zinc Finger ◽

Nuclear Localization ◽

Nuclear Localization Signal ◽

Nuclear Accumulation ◽

Nuclear Factor ◽

Zinc Finger Gene ◽

Early Embryos ◽

Localization Signal ◽

Nuclear Phosphoprotein

Xenopus nuclear factor 7 (xnf7) is a nuclear phosphoprotein that is encoded by a member of a novel zinc finger gene family and likely functions as a transcription factor. It possesses a nuclear localization signal (NLS) similar to the bipartite basic NLS of nucleoplasmin, but unlike nucleoplasmin, which re-enters nuclei immediately after fertilization, xnf7 remains cytoplasmic until the mid-blastula transition (MBT). We have measured the accumulation of injected labeled xnf7 protein or protein produced from synthetic xnf7 transcripts in the oocyte nuclei (GV). The data show that the NLS of xnf7 functions efficiently in oocytes. Mutations in either of the bipartite basic domains of the xnf7 NLS inhibit nuclear accumulation, while mutations in the spacer sequences have no effect. The xnf7 NLS linked to pyruvate kinase directs the efficient accumulation of this protein into nuclei of early embryos prior to the MBT. These data suggest that retention of the xnf7 protein during development is the result of a mechanism that interferes with the xnf7 NLS function.

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Inhibition of Transcription Induces Phosphorylation of YB-1 at Ser102 and Its Accumulation in the Nucleus

Cells ◽

10.3390/cells9010104 ◽

2019 ◽

Vol 9 (1) ◽

pp. 104 ◽

Cited By ~ 2

Author(s):

Dmitry A. Kretov ◽

Daria A. Mordovkina ◽

Irina A. Eliseeva ◽

Dmitry N. Lyabin ◽

Dmitry N. Polyakov ◽

...

Keyword(s):

Gene Expression ◽

Rna Polymerase Ii ◽

Nuclear Localization ◽

Kinase Activity ◽

Binding Protein ◽

Dna Binding Protein ◽

Regulatory Mechanisms ◽

Nuclear Accumulation ◽

Nuclear Retention ◽

Post Translational Modifications

The Y-box binding protein 1 (YB-1) is an RNA/DNA-binding protein regulating gene expression in the cytoplasm and the nucleus. Although mostly cytoplasmic, YB-1 accumulates in the nucleus under stress conditions. Its nuclear localization is associated with aggressiveness and multidrug resistance of cancer cells, which makes the understanding of the regulatory mechanisms of YB-1 subcellular distribution essential. Here, we report that inhibition of RNA polymerase II (RNAPII) activity results in the nuclear accumulation of YB-1 accompanied by its phosphorylation at Ser102. The inhibition of kinase activity reduces YB-1 phosphorylation and its accumulation in the nucleus. The presence of RNA in the nucleus is shown to be required for the nuclear retention of YB-1. Thus, the subcellular localization of YB-1 depends on its post-translational modifications (PTMs) and intracellular RNA distribution.

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Copper Induces Cytoplasmic Retention of Fission Yeast Transcription Factor Cuf1

Eukaryotic Cell ◽

10.1128/ec.5.2.277-292.2006 ◽

2006 ◽

Vol 5 (2) ◽

pp. 277-292 ◽

Cited By ~ 27

Author(s):

Jude Beaudoin ◽

Simon Labbé

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Nuclear Localization ◽

Copper Transport ◽

Nuclear Localization Sequence ◽

Binding Motif ◽

Physical Interaction ◽

Dependent Manner ◽

C Terminus ◽

N Terminus

ABSTRACT Copper homeostasis within the cell is established and preserved by different mechanisms. Changes in gene expression constitute a way of maintaining this homeostasis. In Schizosaccharomyces pombe, the Cuf1 transcription factor is critical for the activation of copper transport gene expression under conditions of copper starvation. However, in the presence of elevated intracellular levels of copper, the mechanism of Cuf1 inactivation to turn off gene expression remains unclear. In this study, we provide evidence that inactivation of copper transport gene expression by Cuf1 is achieved through a copper-dependent, cytosolic retention of Cuf1. We identify a minimal nuclear localization sequence (NLS) between amino acids 11 to 53 within the Cuf1 N terminus. Deletion of this region and specific mutation of the Lys13, Arg16, Arg19, Lys24, Arg28, Lys45, Arg47, Arg50, and Arg53 residues to alanine within this putative NLS is sufficient to abrogate nuclear targeting of Cuf1. Under conditions of copper starvation, Cuf1 resides in the nucleus. However, in the presence of excess copper as well as silver ions, Cuf1 is sequestered in the cytoplasm, a process which requires the putative copper binding motif, 328Cys-X-Cys-X3-Cys-X-Cys-X2-Cys-X2-His342 (designated C-rich), within the C-terminal region of Cuf1. Deletion of this region and mutation of the Cys residues within the C-rich motif result in constitutive nuclear localization of Cuf1. By coexpressing the Cuf1 N terminus with its C terminus in trans and by using a two-hybrid assay, we show that these domains physically interact with each other in a copper-dependent manner. We propose a model wherein copper induces conformational changes in Cuf1 that promote a physical interaction between the Cuf1 N terminus and the C-rich motif in the C terminus that masks the NLS. Cuf1 is thereby sequestered in the cytosol under conditions of copper excess, thereby extinguishing copper transport gene expression.

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The transcription factor Schnurri plays a dual role in mediating Dpp signaling during embryogenesis

Development ◽

10.1242/dev.128.9.1657 ◽

2001 ◽

Vol 128 (9) ◽

pp. 1657-1670 ◽

Cited By ~ 1

Author(s):

J. Torres-Vazquez ◽

S. Park ◽

R. Warrior ◽

K. Arora

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Cell Fate ◽

Target Genes ◽

Gene Activation ◽

Nuclear Accumulation ◽

Embryonic Patterning ◽

Specific Analysis ◽

Positive Input ◽

Affect Gene Expression

Decapentaplegic (Dpp), a homolog of vertebrate bone morphogenic protein 2/4, is crucial for embryonic patterning and cell fate specification in Drosophila. Dpp signaling triggers nuclear accumulation of the Smads Mad and Medea, which affect gene expression through two distinct mechanisms: direct activation of target genes and relief of repression by the nuclear protein Brinker (Brk). The zinc-finger transcription factor Schnurri (Shn) has been implicated as a co-factor for Mad, based on its DNA-binding ability and evidence of signaling dependent interactions between the two proteins. A key question is whether Shn contributes to both repression of brk as well as to activation of target genes. We find that during embryogenesis, brk expression is derepressed in shn mutants. However, while Mad is essential for Dpp-mediated repression of brk, the requirement for shn is stage specific. Analysis of brk; shn double mutants reveals that upregulation of brk does not account for all aspects of the shn mutant phenotype. Several Dpp target genes are expressed at intermediate levels in double mutant embryos, demonstrating that shn also provides a brk-independent positive input to gene activation. We find that Shn-mediated relief of brk repression establishes broad domains of gene activation, while the brk-independent input from Shn is crucial for defining the precise limits and levels of Dpp target gene expression in the embryo.

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Nuclear localization and increased levels of transcription factor YB-1 in primary human breast cancers are associated with intrinsic MDR1 gene expression

Nature Medicine ◽

10.1038/nm0497-447 ◽

1997 ◽

Vol 3 (4) ◽

pp. 447-450 ◽

Cited By ~ 266

Author(s):

Ralf C. Bargou ◽

Karsten Jürchott ◽

Christian Wagener ◽

Stephan Bergmann ◽

Sylvia Metzner ◽

...

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Nuclear Localization ◽

Mdr1 Gene ◽

Breast Cancers ◽

Human Breast ◽

Mdr1 Gene Expression ◽

Primary Human Breast

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Crm1-Mediated Nuclear Export of the Schizosaccharomyces pombe Transcription Factor Cuf1 during a Shift from Low to High Copper Concentrations

Eukaryotic Cell ◽

10.1128/ec.00002-07 ◽

2007 ◽

Vol 6 (5) ◽

pp. 764-775 ◽

Cited By ~ 16

Author(s):

Jude Beaudoin ◽

Simon Labbé

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Schizosaccharomyces Pombe ◽

Nuclear Export ◽

Nuclear Export Signal ◽

Specific Inhibitor ◽

Copper Transport ◽

Nuclear Accumulation ◽

Wild Type ◽

High Copper

ABSTRACT In this study, we examine the fate of the nuclear pool of the Schizosaccharomyces pombe transcription factor Cuf1 in response to variations in copper levels. A nuclear pool of Cuf1-green fluorescent protein (GFP) was generated by expressing a functional cuf1 + -GFP allele in the presence of a copper chelator. We then extinguished cuf1 + -GFP expression and tracked the changes in the localization of the nuclear pool of Cuf1-GFP in the presence of low or high copper concentrations. Treating cells with copper as well as silver ions resulted in the nuclear export of Cuf1. We identified a leucine-rich nuclear export signal (NES), 349LAALNHISAL358, within the C-terminal region of Cuf1. Mutations in this sequence abrogated Cuf1 export from the nucleus. Furthermore, amino acid substitutions that impair Cuf1 NES function resulted in increased target gene expression and a concomitant cellular hypersensitivity to copper. Export of the wild-type Cuf1 protein was inhibited by leptomycin B (LMB), a specific inhibitor of the nuclear export protein Crm1. We further show that cells expressing a temperature-sensitive mutation in crm1 + exhibit increased nuclear accumulation of Cuf1 at the nonpermissive temperature. Although wild-type Cuf1 is localized in the nucleus in both conditions, we observed that the protein can still be inactivated by copper, resulting in the repression of ctr4 + gene expression in the presence of exogenous copper. These results demonstrate that nuclear accumulation of Cuf1 per se is not sufficient to cause the unregulated expression of the copper transport genes like ctr4 + . In addition to nuclear localization, a functional Cys-rich domain or NES element in Cuf1 is required to appropriately regulate copper transport gene expression in response to changes in intracellular copper concentration.

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Effect of Ivermectin and Atorvastatin on Nuclear Localization of Importin Alpha and Drug Target Expression Profiling in Host Cells from Nasopharyngeal Swabs of SARS-CoV-2- Positive Patients

Viruses ◽

10.3390/v13102084 ◽

2021 ◽

Vol 13 (10) ◽

pp. 2084

Author(s):

Valeria Inés Segatori ◽

Juan Garona ◽

Lorena Grisel Caligiuri ◽

Juan Bizzotto ◽

Rosario Lavignolle ◽

...

Keyword(s):

Gene Expression ◽

Nuclear Localization ◽

Rho Gtpases ◽

Nuclear Transport ◽

Host Cells ◽

Poly I:C ◽

Nuclear Accumulation ◽

Synthetic Analog ◽

Importin Α

Nuclear transport and vesicle trafficking are key cellular functions involved in the pathogenesis of RNA viruses. Among other pleiotropic effects on virus-infected host cells, ivermectin (IVM) inhibits nuclear transport mechanisms mediated by importins and atorvastatin (ATV) affects actin cytoskeleton-dependent trafficking controlled by Rho GTPases signaling. In this work, we first analyzed the response to infection in nasopharyngeal swabs from SARS-CoV-2-positive and -negative patients by assessing the gene expression of the respective host cell drug targets importins and Rho GTPases. COVID-19 patients showed alterations in KPNA3, KPNA5, KPNA7, KPNB1, RHOA, and CDC42 expression compared with non-COVID-19 patients. An in vitro model of infection with Poly(I:C), a synthetic analog of viral double-stranded RNA, triggered NF-κB activation, an effect that was halted by IVM and ATV treatment. Importin and Rho GTPases gene expression was also impaired by these drugs. Furthermore, through confocal microscopy, we analyzed the effects of IVM and ATV on nuclear to cytoplasmic importin α distribution, alone or in combination. Results showed a significant inhibition of importin α nuclear accumulation under IVM and ATV treatments. These findings confirm transcriptional alterations in importins and Rho GTPases upon SARS-CoV-2 infection and point to IVM and ATV as valid drugs to impair nuclear localization of importin α when used at clinically-relevant concentrations.

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Nuclear accumulation of the E2F heterodimer regulated by subunit composition and alternative splicing of a nuclear localization signal

Journal of Cell Science ◽

10.1242/jcs.109.10.2443 ◽

1996 ◽

Vol 109 (10) ◽

pp. 2443-2452 ◽

Cited By ~ 1

Author(s):

S. de la Luna ◽

M.J. Burden ◽

C.W. Lee ◽

N.B. La Thangue

Keyword(s):

Cell Cycle ◽

Transcription Factor ◽

Alternative Splicing ◽

Dna Binding ◽

Nuclear Localization ◽

Nuclear Localization Signal ◽

Binding Activity ◽

Nuclear Accumulation ◽

Dna Binding Activity ◽

Localization Signal

The cellular transcription factor E2F plays a critical role in integrating cell cycle progression with the transcription apparatus by virtue of a physical interaction and control by key regulators of the cell cycle, such as pRb, cyclins and cyclin-dependent kinases. Generic E2F DNA binding activity arises when a member of two families of proteins, E2F and DP, form heterodimeric complexes, an interaction which results in co-operative transcriptional and DNA binding activity. Here, we characterise a new and hitherto unexpected mechanism of control influencing the activity of E2F which is mediated at the level of intracellular location through a dependence on heterodimer formation for nuclear translocation. Nuclear accumulation is dramatically influenced by two distinct processes: alternative splicing of a nuclear localization signal and subunit composition of the E2F heterodimer. These data define a new level of control in the E2F transcription factor whereby interplay between subunits dictates the levels of nuclear DNA binding activity.

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The ERBB4/HER4 receptor tyrosine kinase regulates gene expression by functioning as a STAT5A nuclear chaperone

The Journal of Cell Biology ◽

10.1083/jcb.200403155 ◽

2004 ◽

Vol 167 (3) ◽

pp. 469-478 ◽

Cited By ~ 168

Author(s):

Christopher C. Williams ◽

June G. Allison ◽

Gregory A. Vidal ◽

Matthew E. Burow ◽

Barbara S. Beckman ◽

...

Keyword(s):

Breast Cancer ◽

Gene Expression ◽

Transcription Factor ◽

Nuclear Translocation ◽

Cancer Cell Line ◽

Nuclear Accumulation ◽

Intracellular Domain ◽

Receptor Signal ◽

Transcription Factor Target ◽

Lactating Breast

In the lactating breast, ERBB4 localizes to the nuclei of secretory epithelium while regulating activities of the signal transducer and activator of transcription (STAT) 5A transcription factor essential for milk-gene expression. We have identified an intrinsic ERBB4 NLS (residues 676–684) within the ERBB4 intracellular domain (4ICD) that is essential for nuclear accumulation of 4ICD. To determine the functional significance of 4ICD nuclear translocation in a physiologically relevant system, we have demonstrated that cotransfection of ERBB4 and STAT5A in a human breast cancer cell line stimulates β-casein promoter activity. Significantly, nuclear localization of STAT5A and subsequent stimulation of the β-casein promoter requires nuclear translocation of 4ICD. Moreover, 4ICD and STAT5A colocalize within nuclei of heregulin β1 (HRG)-stimulated cells and both proteins bind to the endogenous β-casein promoter in T47D breast cancer cells. Together, our results establish a novel molecular mechanism of transmembrane receptor signal transduction involving nuclear cotranslocation of the receptor intracellular domain and associated transcription factor. Subsequent binding of the two proteins at transcription factor target promoters results in activation of gene expression.

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