scholarly journals RNA-related nuclear functions of human Pat1b, the P-body mRNA decay factor

2012 ◽  
Vol 23 (1) ◽  
pp. 213-224 ◽  
Author(s):  
Aline Marnef ◽  
Dominique Weil ◽  
Nancy Standart
Keyword(s):  
Nuclear Export ◽  
Dependent Manner ◽  
Leptomycin B ◽  
Expression Control ◽  
Gene Expression Control ◽  
Evolutionarily Conserved ◽  
Splicing Speckles ◽  
Body Components ◽  
Nucleocytoplasmic Proteins ◽  
Spliceostatin A

The evolutionarily conserved Pat1 proteins are P-body components recently shown to play important roles in cytoplasmic gene expression control. Using human cell lines, we demonstrate that human Pat1b is a shuttling protein whose nuclear export is mediated via a consensus NES sequence and Crm1, as evidenced by leptomycin B (LMB) treatment. However, not all P-body components are nucleocytoplasmic proteins; rck/p54, Dcp1a, Edc3, Ge-1, and Xrn1 are insensitive to LMB and remain cytoplasmic in its presence. Nuclear Pat1b localizes to PML–associated foci and SC35-containing splicing speckles in a transcription-dependent manner, whereas in the absence of RNA synthesis, Pat1b redistributes to crescent-shaped nucleolar caps. Furthermore, inhibition of splicing by spliceostatin A leads to the reorganization of SC35 speckles, which is closely mirrored by Pat1b, indicating that it may also be involved in splicing processes. Of interest, Pat1b retention in these three nuclear compartments is mediated via distinct regions of the protein. Examination of the nuclear distribution of 4E-T(ransporter), an additional P-body nucleocytoplasmic protein, revealed that 4E-T colocalizes with Pat1b in PML-associated foci but not in nucleolar caps. Taken together, our findings strongly suggest that Pat1b participates in several RNA-related nuclear processes in addition to its multiple regulatory roles in the cytoplasm.

scholarly journals Analysis of the Complex Relationship between Nuclear Export and Aryl Hydrocarbon Receptor-Mediated Gene Regulation

2000 ◽  
Vol 20 (16) ◽  
pp. 6095-6104 ◽  
Author(s):  
Richard S. Pollenz ◽  
E. Rick Barbour
Keyword(s):  
Gene Regulation ◽  
Aryl Hydrocarbon Receptor ◽  
Nuclear Export ◽  
Reporter Genes ◽  
Gene Induction ◽  
Dependent Manner ◽  
Leptomycin B ◽  
Aryl Hydrocarbon ◽  
Negative Effect ◽  
The Relationship

ABSTRACT The aryl hydrocarbon receptor (AHR) contains signals for both nuclear import and nuclear export (NES). The purpose of the studies in this report was to determine the relationship between the nuclear export of the AHR and AHR-mediated gene regulation. Blockage of nuclear export in HepG2 cells with leptomycin B (LMB) resulted in increased levels of AHR-AHR nuclear translocator (ARNT) complex in the nucleus and correlative reductions in agonist-stimulated AHR degradation. However, LMB exposure inhibited agonist-mediated induction of numerous AHR-responsive reporter genes by 75 to 89% and also inhibited induction of endogenous CYP1A1. LMB did not transform the AHR to a ligand binding species or affect activation by TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin). Mutagenesis of leucines 66 and 71 of the putative AHR NES resulted in a protein with reduced function in dimerization to ARNT and binding to DNA, while alanine substitution at leucine 69 (AHRA69) resulted in an AHR that bound with ARNT and associated with DNA. AHRA69protein injected directly into the nuclei of E36 cells remained nuclear following 6 h of agonist stimulation. In transient-transfection assays, AHRA69 accumulated within the nucleus was not degraded efficiently following agonist exposure. Finally, AHRA69 supported induction of AHR-responsive reporter genes in an agonist-dependent manner. These findings show that it is possible to generate an AHR protein defective in nuclear export that is functional in agonist-mediated gene induction. This implies that the negative effect of LMB on agonist-mediated gene induction is independent of the nuclear export of the AHR.

scholarly journals The Mobile FG Nucleoporin Nup98 Is a Cofactor for Crm1-dependent Protein Export

2010 ◽  
Vol 21 (11) ◽  
pp. 1885-1896 ◽  
Author(s):  
Masahiro Oka ◽  
Munehiro Asally ◽  
Yoshinari Yasuda ◽  
Yutaka Ogawa ◽  
Taro Tachibana ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Nuclear Protein ◽  
Mutational Analysis ◽  
Specific Inhibitor ◽  
Protein Export ◽  
Dependent Manner ◽  
Repeat Region ◽  
Leptomycin B ◽  
Dependent Protein ◽  
Nuclear Export Receptor

Nup98 is a mobile nucleoporin that forms distinct dots in the nucleus, and, although a role for Nup98 in nuclear transport has been suggested, its precise function remains unclear. Here, we show that Nup98 plays an important role in Crm1-mediated nuclear protein export. Nuclear, but not cytoplasmic, dots of EGFP-tagged Nup98 disappeared rapidly after cell treatment with leptomycin B, a specific inhibitor of the nuclear export receptor, Crm1. Mutational analysis demonstrated that Nup98 physically and functionally interacts with Crm1 in a RanGTP-dependent manner through its N-terminal phenylalanine-glycine (FG) repeat region. Moreover, the activity of the Nup98-Crm1 complex was modulated by RanBP3, a known cofactor for Crm1-mediated nuclear export. Finally, cytoplasmic microinjection of anti-Nup98 inhibited the Crm1-dependent nuclear export of proteins, concomitant with the accumulation of anti-Nup98 in the nucleus. These results clearly demonstrate that Nup98 functions as a novel shuttling cofactor for Crm1-mediated nuclear export in conjunction with RanBP3.

CBS9106 is a novel reversible oral CRM1 inhibitor with CRM1 degrading activity

Blood ◽  
2011 ◽  
Vol 118 (14) ◽  
pp. 3922-3931 ◽  
Author(s):  
Keiichi Sakakibara ◽  
Naoya Saito ◽  
Takuji Sato ◽  
Atsushi Suzuki ◽  
Yoko Hasegawa ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Significant Loss ◽  
Tumor Xenograft ◽  
Spectrometric Analysis ◽  
Dependent Manner ◽  
Leptomycin B ◽  
Protein Levels ◽  
Cargo Proteins ◽  
Antitumor Properties ◽  
Dose Dependent

Abstract CRM1 plays an important role in the nuclear export of cargo proteins bearing nuclear exporting signal sequences. Leptomycin B (LMB), a well-known CRM1 inhibitor, possesses strong antitumor properties. However, its toxicity prevents it from being clinically useful. In this study, we demonstrate that a novel compound, CBS9106, inhibits CRM1-dependent nuclear export, causing arrest of the cell cycle and inducing apoptosis in a time- and dose-dependent manner for a broad spectrum of cancer cells, including multiple myeloma cells. CBS9106 reduces CRM1 protein levels significantly without affecting CRM1 mRNA expression. This effect could be reversed by adding bortezomib or LMB. Moreover, CBS9106-biotin allows capture of CRM1 protein by streptavidin beads in a competitive manner with LMB and vice versa. Mass spectrometric analysis shows that CBS9106 reacts with a synthetic CRM1 peptide that contains Cys528 but not with a Cys528 mutant peptide. Oral administration of CBS9106 significantly suppresses tumor growth and prolongs survival in mice bearing tumor xenograft without a significant loss in body weight. A reduced level of CRM1 protein is also observed in tumor xenografts isolated from mice treated with CBS9106. Taken together, these results indicate that CBS9106 is a novel reversible CRM1 inhibitor and a promising clinical candidate.

scholarly journals Nuclear Export Factor CRM1 Interacts with Nonstructural Proteins NS2 from Parvovirus Minute Virus of Mice

1999 ◽  
Vol 73 (9) ◽  
pp. 7769-7779 ◽  
Author(s):  
Ursula Bodendorf ◽  
Celina Cziepluch ◽  
Jean-Claude Jauniaux ◽  
Jean Rommelaere ◽  
Nathalie Salomé
Keyword(s):  
Nuclear Export ◽  
Protein A ◽  
Nuclear Accumulation ◽  
Dependent Manner ◽  
Leptomycin B ◽  
Minute Virus Of Mice ◽  
Export Pathway ◽  
Exact Function ◽  
Infected Cells ◽  
Minute Virus

ABSTRACT The nonstructural NS2 proteins of autonomous parvoviruses are known to act in a host cell-dependent manner and to play a role in viral DNA replication, efficient translation of viral mRNA, and/or encapsidation. Their exact function during the parvovirus life cycle remains, however, still obscure. We report here the characterization of the interaction with the NS2 proteins from the parvovirus minute virus of mice (MVM) and rat as well as mouse homologues of the human CRM1 protein, a member of the importin-beta family recently identified as an essential nuclear export factor. Using the two-hybrid system, we could detect the interaction between the carboxy-terminal region of rat CRM1 and each of the three isoforms of NS2 (P [or major], Y [or minor], and L [or rare]). NS2 proteins were further shown to interact with the full-length CRM1 by coimmunoprecipitation experiments using extracts from both mouse and rat cell lines. Our data show that CRM1 preferentially binds to the nonphosphorylated isoforms of NS2. Moreover, we observed that the treatment of MVM-infected cells with leptomycin B, a drug that specifically inhibits the CRM1-dependent nuclear export pathway, leads to a drastic accumulation of NS2 proteins in the nucleus. Both NS2 interaction with CRM1 and nuclear accumulation upon leptomycin B treatment strongly suggest that these nonstructural viral proteins are actively exported out of the nuclei of infected cells via a CRM1-mediated nuclear export pathway.

scholarly journals Efficient RNA Polyuridylation by Noncanonical Poly(A) Polymerases

2007 ◽  
Vol 27 (10) ◽  
pp. 3612-3624 ◽  
Author(s):  
Olivia S. Rissland ◽  
Andrea Mikulasova ◽  
Chris J. Norbury
Keyword(s):  
Nuclear Export ◽  
Polymerase Activity ◽  
Cell Cycle Checkpoint ◽  
Dependent Manner ◽  
Biochemical Activity ◽  
Phase Arrest ◽  
Evolutionarily Conserved ◽  
Cycle Checkpoint ◽  
Human Ortholog

ABSTRACT Nuclear poly(A) polymerase (PAP) polyadenylates nascent mRNAs, promoting their nuclear export, stability, and translation, while the related cytoplasmic polymerase GLD-2 activates translation of deadenylated mRNAs. Here we characterize the biochemical activity of fission yeast Schizosaccharomyces pombe Cid1, a putative cytoplasmic PAP implicated in cell cycle checkpoint controls. Surprisingly, Cid1 has robust poly(U) polymerase activity in vitro, especially when isolated in native multiprotein complexes. Furthermore, we found that upon S-phase arrest, the 3′ ends of actin mRNAs were posttranscriptionally uridylated in a Cid1-dependent manner. Finally, Hs2 (ZCCHC6), a human ortholog of Cid1, shows similar activity. These data suggest that uridylation of mRNA forms the basis of an evolutionarily conserved mechanism of gene regulation.

MALT1 contains nuclear export signals and regulates cytoplasmic localization of BCL10

Blood ◽  
2005 ◽  
Vol 106 (13) ◽  
pp. 4210-4216 ◽  
Author(s):  
Masao Nakagawa ◽  
Yoshitaka Hosokawa ◽  
Masakatsu Yonezumi ◽  
Koh Izumiyama ◽  
Ritsuro Suzuki ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Nuclear Export Signal ◽  
Specific Inhibitor ◽  
B Cell Lymphoma ◽  
Nuclear Factor Κb ◽  
Dependent Manner ◽  
Nucleocytoplasmic Shuttling ◽  
Leptomycin B ◽  
Apoptosis Inhibitor ◽  
Export Signal

MALT1, BCL10 (B-cell lymphoma 10), and API2 (apoptosis inhibitor 2)-MALT1 are key molecules in mucosa-associated lymphoid tissue (MALT) lymphomagenesis. We previously reported that MALT1 and API2-MALT1 were localized only in cytoplasm, where we suggested that both molecules were likely to be active. In the study presented here, we further examined the localization-determining region by generating various mutants and were able to demonstrate that there were nuclear export signal (NES)-containing domains in the MALT1 C-terminal region. The use of leptomycin B, an NES-specific inhibitor, demonstrated that both MALT1 and API2-MALT1 were predominantly retained in the nuclei, indicating that these molecules were shuttling between nucleus and cytoplasm in an NES-dependent manner. It was also found that MALT1 was involved in the nuclear export of BCL10, which is originally localized in both nucleus and cytoplasm. These results correlate well with the nuclear BCL10 expression pattern in both t(1;14) and t(11;18) MALT lymphomas. The nucleocytoplasmic shuttling of MALT1 and BCL10 complex may indicate that these molecules are involved not only in the nuclear factor κB (NF-κB) pathway but also in other biologic functions in lymphocytes.

scholarly journals Gene transcription and chromatin regulation in hypoxia

2020 ◽  
Vol 48 (3) ◽  
pp. 1121-1128 ◽  
Author(s):  
Michael Batie ◽  
Sonia Rocha
Keyword(s):  
Molecular Mechanisms ◽  
Essential Feature ◽  
Hypoxia Inducible Factor ◽  
Transcriptional Response ◽  
Dependent Manner ◽  
Transcriptional Responses ◽  
Oxygen Homeostasis ◽  
Expression Control ◽  
Gene Expression Control ◽  
Key Players

Oxygen sensing is an essential feature of metazoan biology and reductions in oxygen availability (hypoxia) have both physiological and pathophysiological implications. Co-ordinated mechanisms have evolved for sensing and responding to hypoxia, which involve diverse biological outputs, with the main aim of restoring oxygen homeostasis. This includes a dynamic gene transcriptional response, the central drivers of which are the hypoxia-inducible factor (HIF) family of transcription factors. HIFs are regulated in an oxygen-dependent manner and while their role in hypoxia is well established, it is apparent that other key players are required for gene expression control in hypoxia. In this review, we highlight the current understanding of the known and potential molecular mechanisms underpinning gene transcriptional responses to hypoxia in mammals, with a focus on oxygen-dependent effects on chromatin structure.

scholarly journals Transcriptomic uniqueness and commonality of the ion channels and transporters in the four heart chambers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sanda Iacobas ◽  
Bogdan Amuzescu ◽  
Dumitru A. Iacobas
Keyword(s):  
Ion Channels ◽  
Cycle Phase ◽  
Functional Roles ◽  
Expression Control ◽  
Gene Expression Control ◽  
Left And Right ◽  
The Right ◽  
Phase Out ◽  
Right Atria ◽  
Agilent Microarrays

AbstractMyocardium transcriptomes of left and right atria and ventricles from four adult male C57Bl/6j mice were profiled with Agilent microarrays to identify the differences responsible for the distinct functional roles of the four heart chambers. Female mice were not investigated owing to their transcriptome dependence on the estrous cycle phase. Out of the quantified 16,886 unigenes, 15.76% on the left side and 16.5% on the right side exhibited differential expression between the atrium and the ventricle, while 5.8% of genes were differently expressed between the two atria and only 1.2% between the two ventricles. The study revealed also chamber differences in gene expression control and coordination. We analyzed ion channels and transporters, and genes within the cardiac muscle contraction, oxidative phosphorylation, glycolysis/gluconeogenesis, calcium and adrenergic signaling pathways. Interestingly, while expression of Ank2 oscillates in phase with all 27 quantified binding partners in the left ventricle, the percentage of in-phase oscillating partners of Ank2 is 15% and 37% in the left and right atria and 74% in the right ventricle. The analysis indicated high interventricular synchrony of the ion channels expressions and the substantially lower synchrony between the two atria and between the atrium and the ventricle from the same side.

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