Cofactor Requirements for Nuclear Export of Rev Response Element (Rre)–And Constitutive Transport Element (Cte)–Containing Retroviral Rnas

Hofmann, Wilma A.; Reichart, Beate; Ewald, Andrea; Müller, Elvira; Schmitt, Iris; Stauber, Roland H.; Lottspeich, Friedrich; Jockusch, Brigitte M.; Scheer, Ulrich; Hauber, Joachim; Dabauvalle, Marie-Christine

doi:10.1083/jcb.152.5.895

Cited by 200 publications

(165 citation statements)

References 98 publications

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“…Results suggest that F-actin is connected with nuclear membrane proteins, as it is present in nucleus peripheries, besides its internal localization. There are also reports on nuclear actin being associated with nucleoplasmic filaments in nuclear pore complex and participating in transportation, not only retroviral RNA, but also protein kinase inhibitor (PKI) [48]. Our fluorescence microscopy results suggest that the surface localization of F-actin may be involved with nuclear pore in control cells.…”

Section: Discussionsupporting

confidence: 51%

The influence of Trisenox on actin organization in HL-60 cells

et al. 2009

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Abstract:The aim of this study was to show the influence of Trisenox (arsenic trioxide, ATO) on cytoplasmic and nuclear F-actin organization in HL-60 human leukemia cell line. Changes in localization were determined with the use of fluorescence microscopy and flow cytometry. Alterations, in both cytoplasmic and nuclear actin, were observed in cells exposed to ATO. F-actin network underwent accumulation and formed aggregates, that were very often placed under the cell membrane in whole cells and at the periphery of isolated nuclei. Addition of ATO also induced apoptosis and a decrease in G2 phase cells. These results suggest the influence of actin on the formation of apoptotic bodies and also participation of this protein in apoptotic alterations within nuclei, i.e. chromatin reorganization.

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Section: Discussionsupporting

confidence: 51%

The influence of Trisenox on actin organization in HL-60 cells

et al. 2009

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“…This observation would be in line with earlier siRNA-mediated Nup62 depletion studies (79) and was partly explained by the authors as a preferential replenishment of Nup62 at the nuclear pore complex, a phenomenon that may be occurring in HIV-1-expressing cells. This would not represent the first relationship between Nup62 and HIV-1, because Nup62 was also found in a complex that is involved in vRNA nucleocytoplasmic transport (80). Additional work will be necessary to understand how Nup62, as both a component of a nuclear vRNA RNP and nuclear pore complex, contributes to RNA transport and the localization of RNA-binding proteins that shuttle between the nucleus and cytoplasm.…”

Section: Discussionmentioning

confidence: 99%

Human Immunodeficiency Virus Type 1 (HIV-1) Induces the Cytoplasmic Retention of Heterogeneous Nuclear Ribonucleoprotein A1 by Disrupting Nuclear Import

Monette

Ajamian

López-Lastra

et al. 2009

Journal of Biological Chemistry

143

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Human immunodeficiency virus type 1 (HIV-1) co-opts host proteins and cellular machineries to its advantage at every step of the replication cycle. Here we show that HIV-1 enhances heterogeneous nuclear ribonucleoprotein (hnRNP) A1 expression and promotes the relocalization of hnRNP A1 to the cytoplasm. The latter was dependent on the nuclear export of the unspliced viral genomic RNA (vRNA) and to alterations in the abundance and localization of the FG-repeat nuclear pore glycoprotein p62. hnRNP A1 and vRNA remain colocalized in the cytoplasm supporting a post-nuclear function during the late stages of HIV-1 replication. Consistently, we show that hnRNP A1 acts as an internal ribosomal entry site trans-acting factor up-regulating internal ribosome entry site-mediated translation initiation of the HIV-1 vRNA. The up-regulation and cytoplasmic retention of hnRNP A1 by HIV-1 would ensure abundant expression of viral structural proteins in cells infected with HIV-1.During the late stages of the HIV-1 3 replication cycle, the full-length HIV-1 viral RNA (vRNA) must be exported from the nucleus and both translated and packaged into new viral particles (1). The orchestration of these events is directed by a diversity of viral and host proteins that interact with each other and with the vRNA to form HIV-1 ribonucleoprotein (RNP) complexes that originate in the nucleus and persist in the cytoplasm (2). Investigations into the composition and functions of the HIV-1 RNP will reveal new information about innate immunity as well as identify new potential therapeutic targets (3-6).The heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) is a predominantly nuclear protein engaged in a number of cellular and viral RNPs for RNA-processing activities, including splicing regulation, nuclear export, microRNA processing, mRNA stability, telomere maintenance, and IRES-mediated translation initiation (7-12). What enables hnRNP A1 to have such broad functions in RNA metabolism is its ability to bind both nuclear and cytoplasmic RNAs (10). In addition to its well characterized role in nuclear RNA processing, hnRNP A1 binds to purine-rich sequences of mRNAs for mRNA turnover and translation (13,14). Close examination of the HIV-1 vRNA reveals many AG-and AU-rich sequences closely resembling hnRNP A1 binding motifs (15). In fact, hnRNP A1 binds to a number of sequences on the HIV-1 vRNA such as the cis-acting repressive sequences, instability elements, and exonic splicing silencer elements, and indeed, hnRNP A1 is implicated in the fate of HIV-1 RNA, including splicing regulation, nucleocytoplasmic export, and cytoplasmic stability (16 -21).Our previous work demonstrated that hnRNP A1 efficiently immunoprecipitated with the HIV-1 vRNA (22) and that siRNA-mediated knockdown of hnRNP A1 caused a dramatic decrease in HIV-1 structural protein, pr55Gag (herein termed Gag) expression and virus production with little effect on steady-state levels of the three HIV-1 RNA species (i.e. 9-, 4-, and 2-kb RNAs) (23). In this work, we show that HIV-1 ...

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“…A nuclear complex was identified containing nuclear DNA helicase II (NDH II), heterogeneous nuclear ribonucleoprotein C (hnRNP C), and actin (34). Multiple lines of evidence implicate actin in mRNA processing and export: Rapidly labeled RNAs associate with actin in nuclear matrix (35), cytochalasin B causes selective release of precursor mRNA (36), actin localizes adjacent to snRNP aggregates (37), and actin associates with introncontaining HIV-1 gag mRNA (38) and is essential for revmediated mRNA export (39).…”

Section: Discussionmentioning

confidence: 99%

Nuclear actin and protein 4.1: Essential interactions during nuclear assembly in vitro

Krauss

Chen

Penman

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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Structural protein 4.1, which has crucial interactions within the spectrin-actin lattice of the human red cell membrane skeleton, also is widely distributed at diverse intracellular sites in nucleated cells. We previously showed that 4.1 is essential for assembly of functional nuclei in vitro and that the capacity of 4.1 to bind actin is required. Here we report that 4.1 and actin colocalize in mammalian cell nuclei using fluorescence microscopy and, by higherresolution detergent-extracted cell whole-mount electron microscopy, are associated on nuclear filaments. We also devised a cell-free assay using Xenopus egg extract containing fluorescent actin to follow actin during nuclear assembly. By directly imaging actin under nonperturbing conditions, the total nuclear actin population is retained and visualized in situ relative to intact chromatin. We detected actin initially when chromatin and nuclear pores began assembling. As nuclear lamina assembled, but preceding DNA synthesis, actin distributed in a reticulated pattern throughout the nucleus. Protein 4.1 epitopes also were detected when actin began to accumulate in nuclei, producing a diffuse coincident pattern. As nuclei matured, actin was detected both coincident with and also independent of 4.1 epitopes. To test whether acquisition of nuclear actin is required for nuclear assembly, the actin inhibitor latrunculin A was added to Xenopus egg extracts during nuclear assembly. Latrunculin A strongly perturbed nuclear assembly and produced distorted nuclear structures containing neither actin nor protein 4.1. Our results suggest that actin as well as 4.1 is necessary for nuclear assembly and that 4.1-actin interactions may be critical. W e are investigating functions of the protein 4.1 family in nuclei, centrosomes, and mitotic spindles in eukaryotic cells in relation to cell division (1-3). Protein 4.1 is a superfamily of multifunctional structural proteins widely expressed in nucleated cells (4), the prototypical member of which has well defined interactions with spectrin, actin, and integral membrane proteins in the human red cell membrane skeleton (reviewed by refs. 5 and 6). We recently showed that protein 4.1 is essential for proper assembly of functional nuclei in vitro in Xenopus egg extracts and identified the 4.1 spectrin-actin binding domain (SABD) as one of the 4.1 domains critical for this process. Furthermore, using a mutant 4.1 SABD unable to bind actin, we demonstrated that 4.1-actin binding capacity is necessary for nuclear reconstitution (3). These observations prompted us to investigate further the roles of actin in nuclear assembly.Actin is widely recognized as a major cytoskeletal component involved in dynamic processes such as cell motility and shape changes, cytoplasmic vesicle transport, and muscle contraction. Actin also was reported for several decades to be intranuclear, in particular to be associated with nuclear matrix (7-9), although many of these reports initially met with skepticism. Objections included possible cytoplasmic conta...

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Cofactor Requirements for Nuclear Export of Rev Response Element (Rre)–And Constitutive Transport Element (Cte)–Containing Retroviral Rnas

Cited by 200 publications

References 98 publications

The influence of Trisenox on actin organization in HL-60 cells

The influence of Trisenox on actin organization in HL-60 cells

Human Immunodeficiency Virus Type 1 (HIV-1) Induces the Cytoplasmic Retention of Heterogeneous Nuclear Ribonucleoprotein A1 by Disrupting Nuclear Import

Nuclear actin and protein 4.1: Essential interactions during nuclear assembly in vitro

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