Multiple mechanisms promote the inhibition of classical nuclear import upon exposure to severe oxidative stress

Kodiha, Mohamed; Chu, Angel; Matusiewicz, Neola; Stochaj, Ursula

doi:10.1038/sj.cdd.4401432

Cited by 117 publications

(136 citation statements)

References 44 publications

Supporting

Mentioning

131

Contrasting

Order By: Relevance

“…Oxidative and UV stress have both been shown to cause Ran delocalization (Czubryt et al, 2000;Kodiha et al, 2004;Miyamoto et al, 2004). It has recently been reported that the Ran delocalization in response to oxidative stress induced by hydrogen peroxide is due to a stress-induced drop in ATP levels (Yasuda et al, 2006) However, our measurements of nucleotide levels during osmotic stress showed that Ran relocalization does not strictly correlate with changes in energy levels in the cell.…”

Section: The Ran Protein Gradient Is Not Strictly Dependent On Guanincontrasting

confidence: 52%

Hyperosmotic Stress Signaling to the Nucleus Disrupts the Ran Gradient and the Production of RanGTP

Kelley

Paschal

2007

MBoC

View full text Add to dashboard Cite

The RanGTP gradient depends on nucleocytoplasmic shuttling of Ran and its nucleotide exchange in the nucleus. Here we show that hyperosmotic stress signaling induced by sorbitol disrupts the Ran protein gradient and reduces the production of RanGTP. Ran gradient disruption is rapid and is followed by early (10 -20 min) and late (30 -60 min) phases of recovery. Results from SB203580 and siRNA experiments suggest the stress kinase p38 is important for Ran gradient recovery. NTF2 and Mog1, which are transport factors that regulate the nuclear localization of Ran, showed kinetics of delocalization and recovery similar to Ran. Microinjection of a nuclear localization signal reporter protein revealed that sorbitol stress decreases the rate of nuclear import. Sorbitol stress also slowed RCC1 mobility in the nucleus, which is predicted to reduce RCC1 dissociation from chromatin and RanGTP production. This was tested using a FRET biosensor that registers nuclear RanGTP levels, which were reduced in response to sorbitol stress. Although sorbitol alters nucleotide levels, we show that inverting the GTP/GDP ratio in cells is not sufficient to disrupt the Ran gradient. Thus, the Ran system is a target of hyperosmotic stress signaling, and cells use protein localization-based mechanisms as part of a rapid stress response. INTRODUCTIONCells subjected to UV radiation or oxidative, mechanical, or aniso-osmotic stress undergo both short-and long-term adaptation. Hyperosmotic stress induces rapid dehydration that drives an increase in intracellular salt concentration and a decrease in cell volume, placing physical strain on both the cytoskeleton and the plasma membrane (Lang et al., 1998). In response to these changes, cells rapidly initiate a stress signaling cascade and attempt to restore iso-osmolarity through transport of inorganic ions and initiate an accompanying reorganization of the actin cytoskeleton (Haussinger, 1996;Di Ciano et al., 2002). Short-term recovery of cell volume is facilitated by increasing intracellular concentrations of inorganic ions; however, elevated levels of intracellular salts can be detrimental to protein structure and function (Yancey et al., 1982;Russo et al., 2003). Long-term adaptation to hyperosmotic stress is achieved through signal transduction pathways that communicate with the metabolic and transcriptional machinery, resulting in the production or accumulation of organic osmolytes that increase intracellular osmolarity without adversely affecting protein structure or function (O'Neill, 1999).One of the most thoroughly studied stress kinases is the mitogen-activated protein kinase (MAPK) p38. p38 and its yeast homologue Hog1p are activated in response to a wide variety of adverse environmental conditions. These include osmotic, UV, and mechanical stress. Cytokines, such as interleukins and tumor necrosis factor ␣ are also known to activate p38 (Ono and Han, 2000). Hog1p and p38 are both phosphorylated on a threonine, glycine, tyrosine (TGY) motif within the kinase activation loop (Thr 180 an...

show abstract

Section: The Ran Protein Gradient Is Not Strictly Dependent On Guanincontrasting

confidence: 52%

Hyperosmotic Stress Signaling to the Nucleus Disrupts the Ran Gradient and the Production of RanGTP

Kelley

Paschal

2007

MBoC

View full text Add to dashboard Cite

show abstract

“…In addition, there were no gross morphological or structural differences in crosssections between nuclear envelopes of mock and HIV-1-expressing cells. 7 In software-generated surface renditions, the dramatic increase in abundance of Nup62 staining at the nuclear envelope and its spreading into the nuclear matrix may represent signals from the recognition of full-length and several proteolytic products of Nup62 by our two antibodies, as suggested (72,78). 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.…”

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

View full text Add to dashboard Cite

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 ...

show abstract

“…26 Conversely, in response to external stimuli triggering apoptosis, a change in the RanGTP/RanGDP gradient is observed, leading to the inhibition of active nuclear transport. 7,9 In this study, using trypanosomatid protozoa, we have (i) identified Ran and several of its main partners in this divergent cell model, (ii) specified their subcellular localisation at the NPCs and (iii) characterized the apoptotic phenotypes induced by the depletion of their expression.…”

Section: Discussionmentioning

confidence: 99%

“…5 Similarly, the reduction of importin-b and importin-a3 levels leads to an increase in the number of apoptotic cells. 6 Besides, intracellular redistribution of nucleocytoplasmic transport factors is an early feature of apoptosis, which precedes caspase activation, 1,7 and which has been observed in response to cellular stresses including UV irradiation, oxidative stress and heat-shock 8 and hyperosmotic stress. 9 However, it is our opinion that all these reports do not allow inferring any firm conclusions on the link between the inhibition of the nucleocytoplasmic transport and apoptosis, in view of the diverse and essential functions of the proteins studied.…”

mentioning

confidence: 99%

Inhibition of active nuclear transport is an intrinsic trigger of programmed cell death in trypanosomatids

et al. 2008

View full text Add to dashboard Cite

The link between nucleocytoplasmic transport and apoptosis remains controversial. Nucleocytoplasmic exchange of molecules seems indeed essential for the initiation and execution of the apoptotic programme; but inhibition of nuclear transport factors may also represent a powerful apoptotic trigger. The GTPase Ran (together with its partners), first discovered to be essential in nucleocytoplasmic transport, has multiple key functions in cell biology, and particularly in spindle assembly, kinetochore function and nuclear envelope assembly. Among the Ran partners studied, NTF2 appears to be solely involved in nucleocytoplasmic transport. Here, we localised Ran and several of its partners, RanBP1, CAS and NTF2, at the nuclear membrane in the trypanosomatid Leishmania major. Remarkably, these proteins fused to GFP decorated a perinuclear 'collar' of about 15 dots, colocalising at nuclear pore complexes with the homologue of nucleoporin Sec13. In the other trypanosomatid Trypanosoma brucei, RNAi knockdown of the expression of the corresponding genes resulted in an apoptosis-like phenomenon. These phenotypes show that Ran and its partners have a key function in trypanosomatids like they have in mammals. Our data, notably those about TbNTF2 RNAi, support the idea that active nucleocytoplasmic transport is not essential for the initiation and execution of apoptosis, and, rather, the impairment of this transport constitutes an intrinsic signal for triggering PCD.

show abstract

Multiple mechanisms promote the inhibition of classical nuclear import upon exposure to severe oxidative stress

Cited by 117 publications

References 44 publications

Hyperosmotic Stress Signaling to the Nucleus Disrupts the Ran Gradient and the Production of RanGTP

Hyperosmotic Stress Signaling to the Nucleus Disrupts the Ran Gradient and the Production of RanGTP

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

Inhibition of active nuclear transport is an intrinsic trigger of programmed cell death in trypanosomatids

Contact Info

Product

Resources

About