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Kumar MS, Stallworth KM, Murthy AC, Lim SM, Li N, Jain A, Munro JB, Fawzi NL, Lagier-Tourenne C, Bosco DA. Interactions between FUS and the C-terminal Domain of Nup62 are Sufficient for their Co-phase Separation into Amorphous Assemblies. J Mol Biol 2023; 435:167972. [PMID: 36690069 PMCID: PMC10329203 DOI: 10.1016/j.jmb.2023.167972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 12/29/2022] [Accepted: 01/15/2023] [Indexed: 01/22/2023]
Abstract
Deficient nucleocytoplasmic transport is emerging as a pathogenic feature of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), including in ALS caused by mutations in Fused in Sarcoma (FUS). Recently, both wild-type and ALS-linked mutant FUS were shown to directly interact with the phenylalanine-glycine (FG)-rich nucleoporin 62 (Nup62) protein, where FUS WT/ Nup62 interactions were enriched within the nucleus but ALS-linked mutant FUS/ Nup62 interactions were enriched within the cytoplasm of cells. Nup62 is a central channel Nup that has a prominent role in forming the selectivity filter within the nuclear pore complex and in regulating effective nucleocytoplasmic transport. Under conditions where FUS phase separates into liquid droplets in vitro, the addition of Nup62 caused the synergistic formation of amorphous assemblies containing both FUS and Nup62. Here, we examined the molecular determinants of this process using recombinant FUS and Nup62 proteins and biochemical approaches. We demonstrate that the structured C-terminal domain of Nup62 containing an alpha-helical coiled-coil region plays a dominant role in binding FUS and is sufficient for inducing the formation of FUS/Nup62 amorphous assemblies. In contrast, the natively unstructured, F/G repeat-rich N-terminal domain of Nup62 modestly contributed to FUS/Nup62 phase separation behavior. Expression of individual Nup62 domain constructs in human cells confirmed that the Nup62 C-terminal domain is essential for localization of the protein to the nuclear envelope. Our results raise the possibility that interactions between FUS and the C-terminal domain of Nup62 can influence the function of Nup62 under physiological and/or pathological conditions.
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Affiliation(s)
- Meenakshi Sundaram Kumar
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, MA 01605, USA; Biochemistry and Molecular Biotechnology Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Karly M Stallworth
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, MA 01605, USA
| | - Anastasia C Murthy
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Su Min Lim
- Department of Neurology, The Sean M. Healey and AMG Center for ALS at Mass General, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Nan Li
- Department of Neurology, The Sean M. Healey and AMG Center for ALS at Mass General, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Aastha Jain
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - James B Munro
- Department of Microbiology and Physiological Systems, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA; Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Nicolas L Fawzi
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Clotilde Lagier-Tourenne
- Department of Neurology, The Sean M. Healey and AMG Center for ALS at Mass General, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA; Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
| | - Daryl A Bosco
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, MA 01605, USA.
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Zhou T, Li S, Zhong W, Vihervaara T, Béaslas O, Perttilä J, Luo W, Jiang Y, Lehto M, Olkkonen VM, Yan D. OSBP-related protein 8 (ORP8) regulates plasma and liver tissue lipid levels and interacts with the nucleoporin Nup62. PLoS One 2011; 6:e21078. [PMID: 21698267 PMCID: PMC3115989 DOI: 10.1371/journal.pone.0021078] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 05/18/2011] [Indexed: 01/13/2023] Open
Abstract
We earlier identified OSBP-related protein 8 (ORP8) as an endoplasmic reticulum oxysterol-binding protein implicated in cellular lipid homeostasis. We now investigated its action in hepatic cells in vivo and in vitro. Adenoviral overexpression of ORP8 in mouse liver induced a decrease of cholesterol, phospholipids, and triglycerides in serum (−34%, −26%, −37%, respectively) and liver tissue (−40%, −12%, −24%), coinciding with reduction of nuclear (n)SREBP-1 and -2 and mRNA levels of their target genes. Consistently, excess ORP8 reduced nSREBPs in HuH7 cells, and ORP8 overexpression or silencing by RNA interference moderately suppressed or induced the expression of SREBP-1 and SREBP-2 target genes, respectively. In accordance, cholesterol biosynthesis was reduced by ORP8 overexpression and enhanced by ORP8 silencing in [3H]acetate pulse-labeling experiments. ORP8, previously shown to bind 25-hydroxycholesterol, was now shown to bind also cholesterol in vitro. Yeast two-hybrid, bimolecular fluorescence complementation (BiFC), and co-immunoprecipitation analyses revealed the nuclear pore component Nup62 as an interaction partner of ORP8. Co-localization of ORP8 and Nup62 at the nuclear envelope was demonstrated by BiFC and confocal immunofluorescence microscopy. Furthermore, the impact of overexpressed ORP8 on nSREBPs and their target mRNAs was inhibited in cells depleted of Nup62. Our results reveal that ORP8 has the capacity to modulate lipid homeostasis and SREBP activity, probably through an indirect mechanism, and provide clues of an entirely new mode of ORP action.
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Affiliation(s)
- Tianhong Zhou
- Department of Biology, Jinan University, Guangzhou, China
| | - Shiqian Li
- Department of Biology, Jinan University, Guangzhou, China
| | - Wenbin Zhong
- Department of Biology, Jinan University, Guangzhou, China
| | - Terhi Vihervaara
- Minerva Foundation Institute for Medical Research, Biomedicum, Helsinki, Finland
| | - Olivier Béaslas
- Minerva Foundation Institute for Medical Research, Biomedicum, Helsinki, Finland
| | - Julia Perttilä
- Minerva Foundation Institute for Medical Research, Biomedicum, Helsinki, Finland
| | - Wei Luo
- Department of Biology, Jinan University, Guangzhou, China
| | | | - Markku Lehto
- Folkhälsan Institute of Genetics, Folkhälsan Research Centre Biomedicum, Helsinki, Finland
| | - Vesa M. Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum, Helsinki, Finland
- Institute of Biomedicine/Anatomy, University of Helsinki, Helsinki, Finland
- * E-mail: (VMO); (DY)
| | - Daoguang Yan
- Department of Biology, Jinan University, Guangzhou, China
- * E-mail: (VMO); (DY)
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Monette A, Ajamian L, López-Lastra M, Mouland AJ. Human immunodeficiency virus type 1 (HIV-1) induces the cytoplasmic retention of heterogeneous nuclear ribonucleoprotein A1 by disrupting nuclear import: implications for HIV-1 gene expression. J Biol Chem 2009; 284:31350-62. [PMID: 19737937 DOI: 10.1074/jbc.m109.048736] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
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.
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Affiliation(s)
- Anne Monette
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal, Québec H3T 1E2, Canada
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Stochaj U, Bański P, Kodiha M, Matusiewicz N. The N-terminal domain of the mammalian nucleoporin p62 interacts with other nucleoporins of the FXFG family during interphase. Exp Cell Res 2006; 312:2490-9. [PMID: 16730000 DOI: 10.1016/j.yexcr.2006.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 04/10/2006] [Accepted: 04/10/2006] [Indexed: 11/24/2022]
Abstract
Nuclear pore complexes (NPCs) provide the only sites for macromolecular transport between nucleus and cytoplasm. The nucleoporin p62, a component of higher eukaryotic NPCs, is located at the central gated channel and involved in nuclear trafficking of various cargos. p62 is organized into an N-terminal segment that contains FXFG repeats and binds the soluble transport factor NTF2, whereas the C-terminal portion associates with other nucleoporins and importin-beta1. We have now identified new components that interact specifically with the p62 N-terminal domain. Using the p62 N-terminal segment as bait, we affinity-purified nucleoporins Nup358, Nup214 and Nup153 from crude cell extracts. In ligand binding assays, the N-terminal p62 segment associated with Nup358 and p62, suggesting their direct binding to the p62 N-terminal portion. Furthermore, p62 was isolated in complex with Nup358, Nup214 and Nup153 from growing HeLa cells, indicating that the interactions Nup358/p62, Nup214/p62 and p62/Nup153 also occur in vivo. The formation of Nup358/p62 and p62/Nup153 complexes was restricted to interphase cells, whereas Nup214/p62 binding was detected in interphase as well as during mitosis. Our results support a model of complex interactions between FXFG containing nucleoporins, and we propose that some of these interactions may contribute to the movement of cargo across the NPC.
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Affiliation(s)
- Ursula Stochaj
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, Canada PQ H3G 1Y6.
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Kodiha M, Chu A, Matusiewicz N, Stochaj U. Multiple mechanisms promote the inhibition of classical nuclear import upon exposure to severe oxidative stress. Cell Death Differ 2005; 11:862-74. [PMID: 15088071 DOI: 10.1038/sj.cdd.4401432] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
In growing HeLa cells, severe stress elicited by the oxidant hydrogen peroxide inhibits classical nuclear import. Oxidant treatment collapses the nucleocytoplasmic Ran concentration gradient, thereby elevating cytoplasmic GTPase levels. The Ran gradient dissipates in response to a stress-induced depletion of RanGTP and a decreased efficiency of Ran nuclear import. In addition, oxidative stress induces a relocation of the nucleoporin Nup153 as well as the nuclear carrier importin-beta, and docking of the importin-alpha/beta/cargo complex at the nuclear envelope is reduced. Moreover, Ran, importin-beta and Nup153 undergo proteolysis upon oxidative stress. Caspases and the proteasome degrade Ran and importin-beta; however, ubiquitination of these transport factors is not observed. Inhibition of caspases in stressed cells alleviates the mislocalization of importin-beta, but does not restore the Ran concentration gradient or classical import. In summary, inhibition of classical nuclear import by hydrogen peroxide is caused by a combination of multiple mechanisms that target different components of the transport apparatus.
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Affiliation(s)
- M Kodiha
- Department of Physiology, McGill University, 3655 Promenade Sir William Osler, Montreal, PQ, H3G 1Y6, Canada
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Reynolds AE, Ryckman BJ, Baines JD, Zhou Y, Liang L, Roller RJ. U(L)31 and U(L)34 proteins of herpes simplex virus type 1 form a complex that accumulates at the nuclear rim and is required for envelopment of nucleocapsids. J Virol 2001; 75:8803-17. [PMID: 11507225 PMCID: PMC115125 DOI: 10.1128/jvi.75.18.8803-8817.2001] [Citation(s) in RCA: 239] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2001] [Accepted: 06/12/2001] [Indexed: 11/20/2022] Open
Abstract
The herpes simplex virus type 1 (HSV-1) U(L)34 protein is likely a type II membrane protein that localizes within the nuclear membrane and is required for efficient envelopment of progeny virions at the nuclear envelope, whereas the U(L)31 gene product of HSV-1 is a nuclear matrix-associated phosphoprotein previously shown to interact with U(L)34 protein in HSV-1-infected cell lysates. For these studies, polyclonal antisera directed against purified fusion proteins containing U(L)31 protein fused to glutathione-S-transferase (U(L)31-GST) and U(L)34 protein fused to GST (U(L)34-GST) were demonstrated to specifically recognize the U(L)31 and U(L)34 proteins of approximately 34,000 and 30,000 Da, respectively. The U(L)31 and U(L)34 gene products colocalized in a smooth pattern throughout the nuclear rim of infected cells by 10 h postinfection. U(L)34 protein also accumulated in pleiomorphic cytoplasmic structures at early times and associated with an altered nuclear envelope late in infection. Localization of U(L)31 protein at the nuclear rim required the presence of U(L)34 protein, inasmuch as cells infected with a U(L)34 null mutant virus contained U(L)31 protein primarily in central intranuclear domains separate from the nuclear rim, and to a lesser extent in the cytoplasm. Conversely, localization of U(L)34 protein exclusively at the nuclear rim required the presence of the U(L)31 gene product, inasmuch as U(L)34 protein was detectable at the nuclear rim, in replication compartments, and in the cytoplasm of cells infected with a U(L)31 null virus. When transiently expressed in the absence of other viral factors, U(L)31 protein localized diffusely in the nucleoplasm, whereas U(L)34 protein localized primarily in the cytoplasm and at the nuclear rim. In contrast, coexpression of the U(L)31 and U(L)34 proteins was sufficient to target both proteins exclusively to the nuclear rim. The proteins were also shown to directly interact in vitro in the absence of other viral proteins. In cells infected with a virus lacking the U(S)3-encoded protein kinase, previously shown to phosphorylate the U(L)34 gene product, U(L)31 and U(L)34 proteins colocalized in small punctate areas that accumulated on the nuclear rim. Thus, U(S)3 kinase is required for even distribution of U(L)31 and U(L)34 proteins throughout the nuclear rim. Taken together with the similar phenotypes of the U(L)31 and U(L)34 deletion mutants, these data strongly suggest that the U(L)31 and U(L)34 proteins form a complex that accumulates at the nuclear membrane and plays an important role in nucleocapsid envelopment at the inner nuclear membrane.
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Affiliation(s)
- A E Reynolds
- Department of Microbiology and Immunology, Cornell University, Ithaca, New York 14853, USA
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Chughtai ZS, Rassadi R, Matusiewicz N, Stochaj U. Starvation promotes nuclear accumulation of the hsp70 Ssa4p in yeast cells. J Biol Chem 2001; 276:20261-6. [PMID: 11279056 DOI: 10.1074/jbc.m100364200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nuclear import of proteins that are too large to passively enter the nucleus requires soluble factors, energy, and a nuclear localization signal (NLS). Nuclear protein transport can be regulated, and different forms of stress affect nucleocytoplasmic trafficking. As such, import of proteins containing a classical NLS is inhibited in starving yeast cells. In contrast, the hsp70 Ssa4p concentrates in nuclei upon starvation. Nuclear concentration of Ssa4p in starving cells is reversible, and transfer of stationary phase cells to fresh medium induces Ssa4p nuclear export. This export reaction represents an active process that is sensitive to oxidative stress. In starving cells, the N-terminal domain of Ssa4p mediates Ssa4p nuclear accumulation, and a short hydrophobic sequence, termed Star (for starvation), is sufficient to localize the reporter proteins green fluorescent protein or beta-galactosidase to nuclei. To determine whether nuclear accumulation of Star-beta-galactosidase depends on a specific nuclear carrier, we have analyzed its distribution in mutant yeast strains that carry a deletion of a single beta-importin gene. With this assay we have identified Nmd5p as a beta-importin required to concentrate Star-beta-galactosidase in nuclei when cells enter stationary phase.
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Affiliation(s)
- Z S Chughtai
- Department of Physiology, McGill University, Montreal, Province of Quebec H3G 1Y6, Canada
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Chu A, Matusiewicz N, Stochaj U. Heat-induced nuclear accumulation of hsc70s is regulated by phosphorylation and inhibited in confluent cells. FASEB J 2001; 15:1478-80. [PMID: 11387263 DOI: 10.1096/fj.00-0680fje] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- A Chu
- Department of Physiology, McGill University, Montreal, PQ H3G 1Y6, Canada.
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9
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Kretz-Remy C, Michaud S, Tanguay RM. The nuclear chronicles: gene transcription and molecular traveling. Biochem Cell Biol 1999. [DOI: 10.1139/o99-045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The transfer and processing of an RNA transcript from its locus of transcription on chromatin through the nuclear membrane to its site of translation on cytoplasmic ribosomes is a long and complex journey involving numerous processes and interactions with various macromolecules. These various steps that regulate gene expression were the subject of the 9th Winternational Symposium of the Canadian Society of Biochemistry and Molecular & Cell Biology held at Manoir du Lac Delage, a small resort centre north of Québec City on February 12-15, 1999.Key words: nuclear pore, RNA transport, chromatin, RNA-binding proteins, nucleoporins.
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