scholarly journals Differential Nucleocytoplasmic Trafficking between the Related Endocytic Proteins Eps15 and Eps15R

2002 ◽  
Vol 277 (11) ◽  
pp. 8941-8948 ◽  
Author(s):  
Viviane Poupon ◽  
Simona Polo ◽  
Manuela Vecchi ◽  
Gwendal Martin ◽  
Alice Dautry-Varsat ◽  
...  
Keyword(s):  
Nucleocytoplasmic Trafficking ◽  
Endocytic Proteins

scholarly journals Nucleocytoplasmic Shuttling of Endocytic Proteins

2001 ◽  
Vol 153 (7) ◽  
pp. 1511-1518 ◽  
Author(s):  
Manuela Vecchi ◽  
Simona Polo ◽  
Viviane Poupon ◽  
Jan-Willem van de Loo ◽  
Alexandre Benmerah ◽  
...  
Keyword(s):  
Transcriptional Regulation ◽  
Nuclear Export ◽  
Myeloid Leukemia ◽  
Nuclear Translocation ◽  
Initial Rate ◽  
Nucleocytoplasmic Shuttling ◽  
Cellular Processes ◽  
Transactivation Assay ◽  
Ordered Assembly ◽  
Endocytic Proteins

Many cellular processes rely on the ordered assembly of macromolecular structures. Here, we uncover an unexpected link between two such processes, endocytosis and transcription. Many endocytic proteins, including eps15, epsin1, the clathrin assembly lymphoid myeloid leukemia (CALM), and α-adaptin, accumulate in the nucleus when nuclear export is inhibited. Endocytosis and nucleocytoplasmic shuttling of endocytic proteins are apparently independent processes, since inhibition of endocytosis did not appreciably alter nuclear translocation of endocytic proteins, and blockade of nuclear export did not change the initial rate of endocytosis. In the nucleus, eps15 and CALM acted as positive modulators of transcription in a GAL4-based transactivation assay, thus raising the intriguing possibility that some endocytic proteins play a direct or indirect role in transcriptional regulation.

scholarly journals Direct and Indirect Effects on Viral Translation and RNA Replication Are Required for AUF1 Restriction of Enterovirus Infections in Human Cells

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Wendy Ullmer ◽  
Bert L. Semler
Keyword(s):  
Mrna Decay ◽  
Coxsackievirus B3 ◽  
Human Cells ◽  
Human Rhinovirus ◽  
Host Cells ◽  
Paralytic Poliomyelitis ◽  
Common Mechanism ◽  
Restriction Factor ◽  
Nucleocytoplasmic Trafficking ◽  
Viral Translation

ABSTRACTThe cellular mRNA decay protein AUF1 acts as a restriction factor during infection by picornaviruses, including poliovirus, coxsackievirus, and human rhinovirus. AUF1 relocalizes from the nucleus to the cytoplasm during infection by these viruses due to the disruption of nucleocytoplasmic trafficking by viral proteinases. Previous studies have demonstrated that AUF1 binds to poliovirus and coxsackievirus B3 (CVB3) RNA during infection, with binding shown to occur within the internal ribosome entry site (IRES) of the 5′ noncoding region (NCR) or the 3′ NCR, respectively. Binding to different sites within the viral RNA suggests that AUF1 may negatively regulate infection by these viruses using different mechanisms. The work presented here addresses the mechanism of AUF1 inhibition of the replication of poliovirus and CVB3. We demonstrate that AUF1 knockdown in human cells results in increased viral translation, RNA synthesis, and virus production. AUF1 is shown to negatively regulate translation of a poliovirus and CVB3 IRES reporter RNA during infection but not in uninfected cells. We found that this inhibitory activity is not mediated through destabilization of viral genomic RNA; however, it does require virus-induced relocalization of AUF1 from the nucleus to the cytoplasm during the early phases of infection. Our findings suggest that AUF1 restriction of poliovirus and CVB3 replication uses a common mechanism through the viral IRES, which is distinct from the canonical role that AUF1 plays in regulated mRNA decay in uninfected host cells.IMPORTANCEPicornaviruses primarily infect the gastrointestinal or upper respiratory tracts of humans and animals and may disseminate to tissues of the central nervous system, heart, skin, liver, or pancreas. Many common human pathogens belong to thePicornaviridaefamily, which includes viruses known to cause paralytic poliomyelitis (poliovirus); myocarditis (coxsackievirus B3 [CVB3]); the common cold (human rhinovirus [HRV]); and hand, foot, and mouth disease (enterovirus 71 [EV71]), among other illnesses. There are no specific treatments for infection, and vaccines exist for only two picornaviruses: poliovirus and hepatitis A virus. Given the worldwide distribution and prevalence of picornaviruses, it is important to gain insight into the host mechanisms used to restrict infection. Other than proteins involved in the innate immune response, few host factors have been identified that restrict picornavirus replication. The work presented here seeks to define the mechanism of action for the host restriction factor AUF1 during infection by poliovirus and CVB3.

scholarly journals SARS-CoV-2 ORF6 disturbs nucleocytoplasmic trafficking to advance the viral replication

2021 ◽  
Author(s):  
Yoichi Miyamoto ◽  
Yumi Itoh ◽  
Tatsuya Suzuki ◽  
Tomohisa Tanaka ◽  
Yusuke Sakai ◽  
...  
Keyword(s):  
Viral Replication ◽  
Nuclear Translocation ◽  
Nuclear Transport ◽  
Expression Data ◽  
Older Individuals ◽  
Significant Suppression ◽  
Interferon Signaling ◽  
Nucleocytoplasmic Trafficking ◽  
Independent Manner ◽  
Viral Propagation

ABSTRACTSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the coronavirus disease 2019 pandemic. ORF6 is known to antagonize the interferon signaling by inhibiting the nuclear translocation of STAT1. Here we show that ORF6 acts as a virulence factor through two distinct strategies. First, ORF6 directly interacts with STAT1 in an IFN-independent manner to inhibit its nuclear translocation. Second, ORF6 directly binds to importin α1, which is a nuclear transport factor encoded by KPNA2, leading to a significant suppression of importin α1-mediated nuclear transport. Furthermore, we found that KPNA2 knockout enhances the viral replication, suggesting that importin α1 suppresses the viral propagation. Additionally, the analyses of gene expression data revealed that importin α1 levels decreased significantly in the lungs of older individuals. Taken together, SARS-CoV-2 ORF6 disrupts the nucleocytoplasmic trafficking to accelerate the viral replication, resulting in the disease progression, especially in older individuals.

scholarly journals Live-Cell Fluorescence Imaging Reveals the Dynamics of Protein Kinase CK2 Individual Subunits

2003 ◽  
Vol 23 (3) ◽  
pp. 975-987 ◽  
Author(s):  
Odile Filhol ◽  
Arsenio Nueda ◽  
Véronique Martel ◽  
Delphine Gerber-Scokaert ◽  
Maria José Benitez ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nuclear Localization ◽  
Protein Kinase Ck2 ◽  
Fluorescent Protein ◽  
Nuclear Translocation ◽  
Nuclear Accumulation ◽  
Nucleocytoplasmic Trafficking ◽  
Green Fluorescent ◽  
Nucleocytoplasmic Distribution ◽  
Kinase Ck2

ABSTRACT Protein kinase CK2 is a multifunctional enzyme which has long been described as a stable heterotetrameric complex resulting from the association of two catalytic (α or α′) and two regulatory (β) subunits. To track the spatiotemporal dynamics of CK2 in living cells, we fused its catalytic α and regulatory β subunits with green fluorescent protein (GFP). Both CK2 subunits contain nuclear localization domains that target them independently to the nucleus. Imaging of stable cell lines expressing low levels of GFP-CK2α or GFP-CK2β revealed the existence of CK2 subunit subpopulations exhibiting differential dynamics. Once in the nucleus, they diffuse randomly at different rates. Unlike CK2β, CK2α can shuttle, showing the dynamic nature of the nucleocytoplasmic trafficking of the kinase. When microinjected in the cytoplasm, the isolated CK2 subunits are rapidly translocated into the nucleus, whereas the holoenzyme complex remains in this cell compartment, suggesting an intramolecular masking of the nuclear localization sequences that suppresses nuclear accumulation. However, binding of FGF-2 to the holoenzyme triggers its nuclear translocation. Since the substrate specificity of CK2α is dramatically changed by its association with CK2β, the control of the nucleocytoplasmic distribution of each subunit may represent a unique potential regulatory mechanism for CK2 activity.

Abstract P217: Nuclear Protein Import as the Missing Link in Phenylephrine-Induced Cardiomyocyte Hypertrophy

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Mirna N Chahine ◽  
Maxime Mioulane ◽  
Gabor Földes ◽  
Alexander Lyon ◽  
Sian E Harding
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Protein Import ◽  
Nuclear Protein ◽  
Nuclear Translocation ◽  
Cardiomyocyte Hypertrophy ◽  
Nuclear Pore ◽  
Nucleocytoplasmic Trafficking ◽  
Adult Rat ◽  
Nuclear Protein Import

During cardiac hypertrophy, cardiomyocytes (CM) present alterations in gene expression and increased contractile protein content. Nuclear protein import (NPI) is critical in regulating gene expression, transcription, and subsequently cell hypertrophy. However, it is unknown how the nuclear transport machinery (transport receptors and nuclear pore complex (NPC)) functions to sustain increased demands for nucleocytoplasmic trafficking. The aim of this study was to determine if exposure of adult CM to phenylephrine (PE) affects hypertrophy by altering NPI and NPC density. Comparisons were made to adult failing rat and human CM. Rat myocytes were enzymatically isolated from adult hearts, and used for immunocytochemistry, qPCR and western immunoblotting. Failing CM were obtained from explanted human hearts at the time of transplant and from a rat model of myocardial infarction-induced hypertrophy and failure. Rat adult CM exposed for 48h to PE were injected with a protein import substrate (Alexa488-BSA-NLS) to visually monitor nuclear import with the confocal microscope. The effects of P38 MAPK inhibitor, HDAC inhibitor, Exportin-1 (CRM-1) inhibitor, and GSK-3 β inhibitor were investigated. Cell and nuclear sizes were increased in PE treated-adult rat CM and in the adult failing rat and human CM compared to normal CM. In contrast, PE depressed the rate and maximal NPI (by 65 +/- 3.4 % (3.55 from 5.46), p<0.05) as well as nucleoporin p62 mRNA and protein expression levels in adult rat CM compared to non-treated CM. Nucleoporin p62, cytoplasmic Ranbp1, and nuclear translocation of importins (Imp.α and β) relative densities were also decreased in PE treated-adult rat CM and in adult failing rat CM and human heart tissue compared to normal controls. On the contrary, CRM-1 nuclear export relative density was increased during the same pathological conditions. Thus NPI downregulation is linked to an increased nuclear export required by CM to generate the hypertrophic phenotype. All these effects were P38MAPK, HDAC and CRM-1 dependent but GSK-3Beta independent in rat CM. Our results show that alterations in NPI and NPC density occur in failing CM as well as in CM under hypertrophic stimuli. NPI may represent a critical therapeutic target in hypertrophic conditions.

scholarly journals DNA-PK: gatekeeper for IKKγ/NEMO nucleocytoplasmic shuttling in genotoxic stress-induced NF-kappaB activation

2020 ◽  
Vol 77 (20) ◽  
pp. 4133-4142
Author(s):  
Senad Medunjanin ◽  
Maximilian Putzier ◽  
Till Nöthen ◽  
Sönke Weinert ◽  
Thilo Kähne ◽  
...  
Keyword(s):  
Cellular Response ◽  
Phosphorylation Site ◽  
Genotoxic Stress ◽  
Nuclear Factor Κb ◽  
Strand Break ◽  
Nucleocytoplasmic Trafficking ◽  
Dependent Protein Kinase ◽  
Dna Double Strand Break ◽  
Dependent Protein ◽  
Nf Kappab

Abstract The transcription factors of the nuclear factor κB (NF-κB) family play a pivotal role in the cellular response to DNA damage. Genotoxic stress-induced activation of NF-κB differs from the classical canonical pathway by shuttling of the NF-κB Essential Modifier (IKKγ/NEMO) subunit through the nucleus. Here, we show that DNA-dependent protein kinase (DNA-PK), an enzyme involved in DNA double-strand break (DSB) repair, triggers the phosphorylation of NEMO by genotoxic stress, thereby enabling shuttling of NEMO through the nucleus with subsequent NF-κB activation. We identified serine 43 of NEMO as a DNA-PK phosphorylation site and point mutation of this serine to alanine led to a complete block of NF-κB activation by ionizing radiation (IR). Blockade of DNA-PK by a specific shRNA or by DNA-PKcs-deficient cells abrogated NEMO entry into the nucleus, as well. Accordingly, SUMOylation of NEMO, a prerequisite of nuclear NEMO, was abolished. Based on these observations, we propose a model in which NEMO phosphorylation by DNA-PK provides the first step in the nucleocytoplasmic trafficking of NEMO.

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