1
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Penzo A, Palancade B. Puzzling out nuclear pore complex assembly. FEBS Lett 2023; 597:2705-2727. [PMID: 37548888 DOI: 10.1002/1873-3468.14713] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/12/2023] [Accepted: 07/17/2023] [Indexed: 08/08/2023]
Abstract
Nuclear pore complexes (NPCs) are sophisticated multiprotein assemblies embedded within the nuclear envelope and controlling the exchanges of molecules between the cytoplasm and the nucleus. In this review, we summarize the mechanisms by which these elaborate complexes are built from their subunits, the nucleoporins, based on our ever-growing knowledge of NPC structural organization and on the recent identification of additional features of this process. We present the constraints faced during the production of nucleoporins, their gathering into oligomeric complexes, and the formation of NPCs within nuclear envelopes, and review the cellular strategies at play, from co-translational assembly to the enrolment of a panel of cofactors. Remarkably, the study of NPCs can inform our perception of the biogenesis of multiprotein complexes in general - and vice versa.
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Affiliation(s)
- Arianna Penzo
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
| | - Benoit Palancade
- Université Paris Cité, CNRS, Institut Jacques Monod, Paris, France
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2
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Mannino PJ, Lusk CP. Quality control mechanisms that protect nuclear envelope identity and function. J Biophys Biochem Cytol 2022; 221:213424. [PMID: 36036741 PMCID: PMC9442147 DOI: 10.1083/jcb.202205123] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 11/22/2022] Open
Abstract
The nuclear envelope (NE) is a specialization of the endoplasmic reticulum with distinct biochemistry that defines inner and outer membranes connected at a pore membrane that houses nuclear pore complexes (NPCs). Quality control mechanisms that maintain the physical integrity and biochemical identity of these membranes are critical to ensure that the NE acts as a selective barrier that also contributes to genome stability and metabolism. As the proteome of the NE is highly integrated, it is challenging to turn over by conventional ubiquitin-proteasome and autophagy mechanisms. Further, removal of entire sections of the NE requires elaborate membrane remodeling that is poorly understood. Nonetheless, recent work has made inroads into discovering specializations of cellular degradative machineries tailored to meeting the unique challenges imposed by the NE. In addition, cells have evolved mechanisms to surveil and repair the NE barrier to protect against the deleterious effects of a breach in NE integrity, in the form of either a ruptured NE or a dysfunctional NPC. Here, we synthesize the most recent work exploring NE quality control mechanisms across eukaryotes.
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3
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Deolal P, Jamir I, Mishra K. Uip4p modulates nuclear pore complex function in Saccharomyces cerevisiae. Nucleus 2022; 13:79-93. [PMID: 35171083 PMCID: PMC8855845 DOI: 10.1080/19491034.2022.2034286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A double membrane bilayer perforated by nuclear pore complexes (NPCs) governs the shape of the nucleus, the prominent distinguishing organelle of a eukaryotic cell. Despite the absence of lamins in yeasts, the nuclear morphology is stably maintained and shape changes occur in a regulated fashion. In a quest to identify factors that contribute to regulation of nuclear shape and function in Saccharomyces cerevisiae, we used a fluorescence imaging based approach. Here we report the identification of a novel protein, Uip4p, that is required for regulation of nuclear morphology. Loss of Uip4 compromises NPC function and loss of nuclear envelope (NE) integrity. Our localization studies show that Uip4 localizes to the NE and endoplasmic reticulum (ER) network. Furthermore, we demonstrate that the localization and expression of Uip4 is regulated during growth, which is crucial for NPC distribution.
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Affiliation(s)
- Pallavi Deolal
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Imlitoshi Jamir
- Department of Biotechnology, School of Engineering and Technology, Nagaland University, Dimapur, India
| | - Krishnaveni Mishra
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
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4
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Brown JT, Haraczy AJ, Wilhelm CM, Belanger KD. Characterization of nuclear pore complex targeting domains in Pom152 in Saccharomyces cerevisiae. Biol Open 2021; 10:272274. [PMID: 34557894 PMCID: PMC8543022 DOI: 10.1242/bio.057661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 09/20/2021] [Indexed: 11/20/2022] Open
Abstract
Pom152 is a transmembrane protein within the nuclear pore complex (NPC) of fungi that is important for NPC assembly and structure. Pom152 is comprised of a short amino-terminal region that remains on the cytosolic side of the nuclear envelope (NE) and interacts with NPC proteins, a transmembrane domain, and a large, glycosylated carboxy-terminal domain within the NE lumen. Here we show that the N-terminal 200 amino acids of Pom152 that include only the amino-terminal and transmembrane regions are sufficient for localization to the NPC. Full-length, glycosylation-deficient, and truncated Pom152-GFP chimeras expressed in cells containing endogenous Pom152 localize to both NPCs and cortical endoplasmic reticulum (ER). Expression of Pom152-GFP fusions in pom152Δ cells results in detectable localization at only the NE by full-length and amino-terminal Pom152-GFP fusions, but continued retention at both the NE and ER for a chimera lacking just the carboxy-terminal 377 amino acids. Neither deletion of Pom152 nor its carboxy-terminal glycosylation sites altered the nuclear protein export rate of an Msn5/Kap142 protein cargo. These data narrow the Pom152 region sufficient for NPC localization and provide evidence that alterations in other domains may impact Pom152 targeting or affinity for the NPC. Summary: Pom152 is a transmembrane nucleoporin important for nuclear pore complex structure and synthesis. Here we further characterize Pom152, showing that the cytosolic and transmembrane domains are sufficient for NPC localization.
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5
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Deolal P, Mishra K. Regulation of diverse nuclear shapes: pathways working independently, together. Commun Integr Biol 2021; 14:158-175. [PMID: 34262635 PMCID: PMC8259725 DOI: 10.1080/19420889.2021.1939942] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/02/2021] [Accepted: 06/03/2021] [Indexed: 12/16/2022] Open
Abstract
Membrane-bound organelles provide physical and functional compartmentalization of biological processes in eukaryotic cells. The characteristic shape and internal organization of these organelles is determined by a combination of multiple internal and external factors. The maintenance of the shape of nucleus, which houses the genetic material within a double membrane bilayer, is crucial for a seamless spatio-temporal control over nuclear and cellular functions. Dynamic morphological changes in the shape of nucleus facilitate various biological processes. Chromatin packaging, nuclear and cytosolic protein organization, and nuclear membrane lipid homeostasis are critical determinants of overall nuclear morphology. As such, a multitude of molecular players and pathways act together to regulate the nuclear shape. Here, we review the known mechanisms governing nuclear shape in various unicellular and multicellular organisms, including the non-spherical nuclei and non-lamin-related structural determinants. The review also touches upon cellular consequences of aberrant nuclear morphologies.
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Affiliation(s)
- Pallavi Deolal
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Krishnaveni Mishra
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
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6
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Capella M, Martín Caballero L, Pfander B, Braun S, Jentsch S. ESCRT recruitment by the S. cerevisiae inner nuclear membrane protein Heh1 is regulated by Hub1-mediated alternative splicing. J Cell Sci 2020; 133:jcs250688. [PMID: 33262311 DOI: 10.1242/jcs.250688] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 11/17/2020] [Indexed: 12/28/2022] Open
Abstract
Misassembled nuclear pore complexes (NPCs) are removed by sealing off the surrounding nuclear envelope (NE), which is conducted by the endosomal sorting complexes required for transport (ESCRT) machinery. Recruitment of ESCRT proteins to the NE is mediated by the interaction between the ESCRT member Chm7 and the inner nuclear membrane protein Heh1, which belongs to the conserved LEM family. Increased ESCRT recruitment results in excessive membrane scission at damage sites but its regulation remains poorly understood. Here, we show that Hub1-mediated alternative splicing of HEH1 pre-mRNA, resulting in production of its shorter form Heh1-S, is critical for the integrity of the NE in Saccharomyces cerevisiae ESCRT-III mutants lacking Hub1 or Heh1-S display severe growth defects and accumulate improperly assembled NPCs. This depends on the interaction of Chm7 with the conserved MSC domain, which is only present in the longer variant Heh1-L. Heh1 variants assemble into heterodimers, and we demonstrate that a unique splice segment in Heh1-S suppresses growth defects associated with the uncontrolled interaction between Heh1-L and Chm7. Together, our findings reveal that Hub1-mediated splicing generates Heh1-S to regulate ESCRT recruitment to the NE.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Matías Capella
- Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
| | - Lucía Martín Caballero
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
| | - Boris Pfander
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
- DNA Replication and Genome Integrity, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Sigurd Braun
- Department of Physiological Chemistry, Biomedical Center (BMC), Ludwig Maximilians University of Munich, 82152 Martinsried, Germany
- International Max Planck Research School for Molecular and Cellular Life Sciences, 82152 Martinsried, Germany
| | - Stefan Jentsch
- Molecular Cell Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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7
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High-Throughput Identification of Nuclear Envelope Protein Interactions in Schizosaccharomyces pombe Using an Arrayed Membrane Yeast-Two Hybrid Library. G3-GENES GENOMES GENETICS 2020; 10:4649-4663. [PMID: 33109728 PMCID: PMC7718735 DOI: 10.1534/g3.120.401880] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The nuclear envelope (NE) contains a specialized set of integral membrane proteins that maintain nuclear shape and integrity and influence chromatin organization and gene expression. Advances in proteomics techniques and studies in model organisms have identified hundreds of proteins that localize to the NE. However, the function of many of these proteins at the NE remains unclear, in part due to a lack of understanding of the interactions that these proteins participate in at the NE membrane. To assist in the characterization of NE transmembrane protein interactions we developed an arrayed library of integral and peripheral membrane proteins from the fission yeast Schizosaccharomyces pombe for high-throughput screening using the split-ubiquitin based membrane yeast two -hybrid system. We used this approach to characterize protein interactions for three conserved proteins that localize to the inner nuclear membrane: Cut11/Ndc1, Lem2 and Ima1/Samp1/Net5. Additionally, we determined how the interaction network for Cut11 is altered in canonical temperature-sensitive cut11-ts mutants. This library and screening approach is readily applicable to characterizing the interactomes of integral membrane proteins localizing to various subcellular compartments.
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8
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Expósito-Serrano M, Sánchez-Molina A, Gallardo P, Salas-Pino S, Daga RR. Selective Nuclear Pore Complex Removal Drives Nuclear Envelope Division in Fission Yeast. Curr Biol 2020; 30:3212-3222.e2. [DOI: 10.1016/j.cub.2020.05.066] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/24/2020] [Accepted: 05/20/2020] [Indexed: 01/09/2023]
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9
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Rempel IL, Popken P, Ghavami A, Mishra A, Hapsari RA, Wolters AHG, Veldsink AC, Klaassens M, Meinema AC, Poolman B, Giepmans BNG, Onck PR, Steen A, Veenhoff LM. Flexible and Extended Linker Domains Support Efficient Targeting of Heh2 to the Inner Nuclear Membrane. Structure 2020; 28:185-195.e5. [PMID: 31806352 DOI: 10.1016/j.str.2019.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 08/09/2019] [Accepted: 11/08/2019] [Indexed: 10/25/2022]
Abstract
The nuclear pore complex (NPC) is embedded in the nuclear envelope and forms the main gateway to the nuclear interior including the inner nuclear membrane (INM). Two INM proteins in yeast are selectively imported. Their sorting signals consist of a nuclear localization signal, separated from the transmembrane domain by a long intrinsically disordered (ID) linker. We used computational models to predict the dynamic conformations of ID linkers and analyzed the INM targeting efficiency of proteins with linker regions with altered Stokes radii and decreased flexibilities. We find that flexibility, Stokes radius, and the frequency at which the linkers are at an extended end-to-end distance larger than 25 nm are good predictors for the targeting of the proteins. The data are consistent with a transport mechanism in which INM targeting of Heh2 is dependent on an ID linker that facilitates the crossing of the approximately 25-nm thick NPC scaffold.
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Affiliation(s)
- Irina L Rempel
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands
| | - Petra Popken
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands; Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands; Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
| | - Ali Ghavami
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
| | - Ankur Mishra
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
| | - Rizqiya A Hapsari
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands
| | - Anouk H G Wolters
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands
| | - Annemiek C Veldsink
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands
| | - Marindy Klaassens
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands
| | - Anne C Meinema
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
| | - Bert Poolman
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands; Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
| | - Ben N G Giepmans
- Department of Biomedical Sciences of Cells and Systems, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands
| | - Patrick R Onck
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands.
| | - Anton Steen
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands.
| | - Liesbeth M Veenhoff
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, Netherlands.
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10
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Thaller DJ, Allegretti M, Borah S, Ronchi P, Beck M, Lusk CP. An ESCRT-LEM protein surveillance system is poised to directly monitor the nuclear envelope and nuclear transport system. eLife 2019; 8:e45284. [PMID: 30942170 PMCID: PMC6461442 DOI: 10.7554/elife.45284] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/02/2019] [Indexed: 12/22/2022] Open
Abstract
The integrity of the nuclear membranes coupled to the selective barrier of nuclear pore complexes (NPCs) are essential for the segregation of nucleoplasm and cytoplasm. Mechanical membrane disruption or perturbation to NPC assembly triggers an ESCRT-dependent surveillance system that seals nuclear pores: how these pores are sensed and sealed is ill defined. Using a budding yeast model, we show that the ESCRT Chm7 and the integral inner nuclear membrane (INM) protein Heh1 are spatially segregated by nuclear transport, with Chm7 being actively exported by Xpo1/Crm1. Thus, the exposure of the INM triggers surveillance with Heh1 locally activating Chm7. Sites of Chm7 hyperactivation show fenestrated sheets at the INM and potential membrane delivery at sites of nuclear envelope herniation. Our data suggest that perturbation to the nuclear envelope barrier would lead to local nuclear membrane remodeling to promote membrane sealing. Our findings have implications for disease mechanisms linked to NPC assembly and nuclear envelope integrity.
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Affiliation(s)
- David J Thaller
- Department of Cell BiologyYale School of MedicineNew HavenUnited States
| | - Matteo Allegretti
- Structural and Computational Biology UnitEuropean Molecular Biology LaboratoryMeyerhofstrasseGermany
| | - Sapan Borah
- Department of Cell BiologyYale School of MedicineNew HavenUnited States
| | - Paolo Ronchi
- Electron Microscopy Core FacilityEuropean Molecular Biology LaboratoryMeyerhofstrasseGermany
| | - Martin Beck
- Structural and Computational Biology UnitEuropean Molecular Biology LaboratoryMeyerhofstrasseGermany
| | - C Patrick Lusk
- Department of Cell BiologyYale School of MedicineNew HavenUnited States
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11
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Abstract
The nuclear pore complex (NPC) serves as the sole bidirectional gateway of macromolecules in and out of the nucleus. Owing to its size and complexity (∼1,000 protein subunits, ∼110 MDa in humans), the NPC has remained one of the foremost challenges for structure determination. Structural studies have now provided atomic-resolution crystal structures of most nucleoporins. The acquisition of these structures, combined with biochemical reconstitution experiments, cross-linking mass spectrometry, and cryo-electron tomography, has facilitated the determination of the near-atomic overall architecture of the symmetric core of the human, fungal, and algal NPCs. Here, we discuss the insights gained from these new advances and outstanding issues regarding NPC structure and function. The powerful combination of bottom-up and top-down approaches toward determining the structure of the NPC offers a paradigm for uncovering the architectures of other complex biological machines to near-atomic resolution.
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Affiliation(s)
- Daniel H Lin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
| | - André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA;
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12
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Chalfant M, Barber KW, Borah S, Thaller D, Lusk CP. Expression of TorsinA in a heterologous yeast system reveals interactions with lumenal domains of LINC and nuclear pore complex components. Mol Biol Cell 2019; 30:530-541. [PMID: 30625036 PMCID: PMC6589686 DOI: 10.1091/mbc.e18-09-0585] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
DYT1 dystonia is caused by an in-frame deletion of a glutamic acid codon in the gene encoding the AAA+ ATPase TorsinA (TorA). TorA localizes within the lumen of the nuclear envelope/endoplasmic reticulum and binds to a membrane-spanning cofactor, lamina associated polypeptide 1 (LAP1) or lumenal domain like LAP1 (LULL1), to form an ATPase; the substrate(s) of TorA remains ill-defined. Here we use budding yeast, which lack Torsins, to interrogate TorA function. We show that TorA accumulates at nuclear envelope-embedded spindle pole bodies (SPBs) in a way that requires its oligomerization and the SUN (Sad1 and UNc-84)-domain protein, Mps3. We further show that TorA physically interacts with human SUN1/2 within this system, supporting the physiological relevance of these interactions. Consistent with the idea that TorA acts on a SPB substrate, its binding to SPBs is modulated by the ATPase-stimulating activity of LAP1. TorA and TorA-ΔE reduce the fitness of cells expressing mps3 alleles, whereas TorA alone inhibits growth of cells lacking Pom152, a component of the nuclear pore complex. This genetic specificity is mirrored biochemically as TorA, but not TorA-ΔE, binds Pom152. Thus, TorA–nucleoporin interactions might be abrogated by TorA-ΔE, suggesting new experimental avenues to interrogate the molecular basis behind nuclear envelope herniations seen in mammalian cells lacking TorA function.
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Affiliation(s)
| | - Karl W. Barber
- Department of Cellular and Molecular Physiology, Yale School of Medicine, Yale University, New Haven, CT 06520
- Systems Biology Institute, Yale University, West Haven, CT 06477
| | - Sapan Borah
- Department of Cell Biology, Yale University, New Haven, CT 06520
| | - David Thaller
- Department of Cell Biology, Yale University, New Haven, CT 06520
| | - C. Patrick Lusk
- Department of Cell Biology, Yale University, New Haven, CT 06520
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13
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Dutta S, Bhattacharyya M, Sengupta K. Changes in the Nuclear Envelope in Laminopathies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1112:31-38. [PMID: 30637688 DOI: 10.1007/978-981-13-3065-0_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
Double-membrane-bound nucleus is the major organelle of every metazoan cell, which controls various nuclear processes like chromatin maintenance, DNA replication, transcription and nucleoskeleton-cytoskeleton coupling. Nuclear homeostasis depends on the integrity of nuclear membrane and associated proteins. Lamins, underlying the inner nuclear membrane (INM), play a crucial role in maintaining nuclear homeostasis. In this review, we have focussed on the disruption of nuclear homeostasis due to lamin A/C mutation which produces a plethora of diseases, termed as laminopathies.
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Affiliation(s)
- Subarna Dutta
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, West Bengal, India
- Department of Biochemistry, University of Calcutta, Kolkata, West Bengal, India
| | | | - Kaushik Sengupta
- Biophysics & Structural Genomics Division, Saha Institute of Nuclear Physics, Kolkata, West Bengal, India.
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14
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Fantastic nuclear envelope herniations and where to find them. Biochem Soc Trans 2018; 46:877-889. [PMID: 30026368 DOI: 10.1042/bst20170442] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/02/2018] [Accepted: 05/04/2018] [Indexed: 12/19/2022]
Abstract
Morphological abnormalities of the bounding membranes of the nucleus have long been associated with human diseases from cancer to premature aging to neurodegeneration. Studies over the past few decades support that there are both cell intrinsic and extrinsic factors (e.g. mechanical force) that can lead to nuclear envelope 'herniations', a broad catch-all term that reveals little about the underlying molecular mechanisms that contribute to these morphological defects. While there are many genetic perturbations that could ultimately change nuclear shape, here, we focus on a subset of nuclear envelope herniations that likely arise as a consequence of disrupting physiological nuclear membrane remodeling pathways required to maintain nuclear envelope homeostasis. For example, stalling of the interphase nuclear pore complex (NPC) biogenesis pathway and/or triggering of NPC quality control mechanisms can lead to herniations in budding yeast, which are remarkably similar to those observed in human disease models of early-onset dystonia. By also examining the provenance of nuclear envelope herniations associated with emerging nuclear autophagy and nuclear egress pathways, we will provide a framework to help understand the molecular pathways that contribute to nuclear deformation.
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15
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Borlido J, Sakuma S, Raices M, Carrette F, Tinoco R, Bradley LM, D'Angelo MA. Nuclear pore complex-mediated modulation of TCR signaling is required for naïve CD4 + T cell homeostasis. Nat Immunol 2018; 19:594-605. [PMID: 29736031 PMCID: PMC5976539 DOI: 10.1038/s41590-018-0103-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 03/28/2018] [Indexed: 11/09/2022]
Abstract
Nuclear pore complexes (NPCs) are channels connecting the nucleus with the cytoplasm. We report that loss of the tissue-specific NPC component Nup210 causes a severe deficit of naïve CD4+ T cells. Nup210-deficient CD4+ T lymphocytes develop normally but fail to survive in the periphery. The decreased survival results from both an impaired ability to transmit tonic T cell receptor (TCR) signals and increased levels of Fas, which sensitize Nup210-/- naïve CD4+ T cells to Fas-mediated cell death. Mechanistically, Nup210 regulates these processes by modulating the expression of Cav2 (encoding Caveolin-2) and Jun at the nuclear periphery. Whereas the TCR-dependent and CD4+ T cell-specific upregulation of Cav2 is critical for proximal TCR signaling, cJun expression is required for STAT3-dependent repression of Fas. Our results uncover an unexpected role for Nup210 as a cell-intrinsic regulator of TCR signaling and T cell homeostasis and expose NPCs as key players in the adaptive immune system.
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Affiliation(s)
- Joana Borlido
- Development, Aging and Regeneration Program and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Stephen Sakuma
- Development, Aging and Regeneration Program and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Marcela Raices
- Development, Aging and Regeneration Program and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Florent Carrette
- Infectious and Inflammatory Disease Center and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Roberto Tinoco
- Infectious and Inflammatory Disease Center and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Linda M Bradley
- Infectious and Inflammatory Disease Center and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Maximiliano A D'Angelo
- Development, Aging and Regeneration Program and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
- Infectious and Inflammatory Disease Center and NCI-Designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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16
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Growing functions of the ESCRT machinery in cell biology and viral replication. Biochem Soc Trans 2017; 45:613-634. [PMID: 28620025 DOI: 10.1042/bst20160479] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 02/17/2017] [Accepted: 02/21/2017] [Indexed: 01/31/2023]
Abstract
The vast expansion in recent years of the cellular processes promoted by the endosomal sorting complex required for transport (ESCRT) machinery has reinforced its identity as a modular system that uses multiple adaptors to recruit the core membrane remodelling activity at different intracellular sites and facilitate membrane scission. Functional connections to processes such as the aurora B-dependent abscission checkpoint also highlight the importance of the spatiotemporal regulation of the ESCRT machinery. Here, we summarise the role of ESCRTs in viral budding, and what we have learned about the ESCRT pathway from studying this process. These advances are discussed in the context of areas of cell biology that have been transformed by research in the ESCRT field, including cytokinetic abscission, nuclear envelope resealing and plasma membrane repair.
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17
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Zhu Q, Zheng F, Liu AP, Qian J, Fu C, Lin Y. Shape Transformation of the Nuclear Envelope during Closed Mitosis. Biophys J 2017; 111:2309-2316. [PMID: 27851952 DOI: 10.1016/j.bpj.2016.10.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 09/28/2016] [Accepted: 10/07/2016] [Indexed: 11/18/2022] Open
Abstract
The nuclear envelope (NE) in lower eukaryotes such as Schizosaccharomyces pombe undergoes large morphology changes during closed mitosis. However, which physical parameters are important in governing the shape evolution of the NE, and how defects in the dividing chromosomes/microtubules are reflected in those parameters, are fundamental questions that remain unresolved. In this study, we show that improper separation of chromosomes in genetically deficient cells leads to membrane tethering or asymmetric division in contrast to the formation of two equal-sized daughter nuclei in wild-type cells. We hypothesize that the poleward force is transmitted to the nuclear membrane through its physical contact with the separated sister chromatids at the two spindle poles. A theoretical model is developed to predict the morphology evolution of the NE where key factors such as the work done by the poleward force and bending and surface energies stored in the membrane have been taken into account. Interestingly, the predicted phase diagram, summarizing the dependence of nuclear shape on the size of the load transmission regions, and the pole-to-pole distance versus surface area relationship all quantitatively agree well with our experimental observations, suggesting that this model captures the essential physics involved in closed mitosis.
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Affiliation(s)
- Qian Zhu
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China
| | - Fan Zheng
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan
| | - Jin Qian
- Department of Engineering Mechanics, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chuanhai Fu
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.
| | - Yuan Lin
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong SAR, China.
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18
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Molecular Architecture of the Major Membrane Ring Component of the Nuclear Pore Complex. Structure 2017; 25:434-445. [PMID: 28162953 DOI: 10.1016/j.str.2017.01.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/06/2017] [Accepted: 01/19/2017] [Indexed: 02/06/2023]
Abstract
The membrane ring that equatorially circumscribes the nuclear pore complex (NPC) in the perinuclear lumen of the nuclear envelope is composed largely of Pom152 in yeast and its ortholog Nup210 (or Gp210) in vertebrates. Here, we have used a combination of negative-stain electron microscopy, nuclear magnetic resonance, and small-angle X-ray scattering methods to determine an integrative structure of the ∼120 kDa luminal domain of Pom152. Our structural analysis reveals that the luminal domain is formed by a flexible string-of-pearls arrangement of nine repetitive cadherin-like Ig-like domains, indicating an evolutionary connection between NPCs and the cell adhesion machinery. The 16 copies of Pom152 known to be present in the yeast NPC are long enough to form the observed membrane ring, suggesting how interactions between Pom152 molecules help establish and maintain the NPC architecture.
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19
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Webster BM, Thaller DJ, Jäger J, Ochmann SE, Borah S, Lusk CP. Chm7 and Heh1 collaborate to link nuclear pore complex quality control with nuclear envelope sealing. EMBO J 2016; 35:2447-2467. [PMID: 27733427 DOI: 10.15252/embj.201694574] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 11/09/2022] Open
Abstract
The integrity of the nuclear envelope barrier relies on membrane remodeling by the ESCRTs, which seal nuclear envelope holes and contribute to the quality control of nuclear pore complexes (NPCs); whether these processes are mechanistically related remains poorly defined. Here, we show that the ESCRT-II/III chimera, Chm7, is recruited to a nuclear envelope subdomain that expands upon inhibition of NPC assembly and is required for the formation of the storage of improperly assembled NPCs (SINC) compartment. Recruitment to sites of NPC assembly is mediated by its ESCRT-II domain and the LAP2-emerin-MAN1 (LEM) family of integral inner nuclear membrane proteins, Heh1 and Heh2. We establish direct binding between Heh2 and the "open" forms of both Chm7 and the ESCRT-III, Snf7, and between Chm7 and Snf7. Interestingly, Chm7 is required for the viability of yeast strains where double membrane seals have been observed over defective NPCs; deletion of CHM7 in these strains leads to a loss of nuclear compartmentalization suggesting that the sealing of defective NPCs and nuclear envelope ruptures could proceed through similar mechanisms.
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Affiliation(s)
- Brant M Webster
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - David J Thaller
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - Jens Jäger
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - Sarah E Ochmann
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - Sapan Borah
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
| | - C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, New Haven, CT, USA
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20
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A model for coordinating nuclear mechanics and membrane remodeling to support nuclear integrity. Curr Opin Cell Biol 2016; 41:9-17. [PMID: 27031045 DOI: 10.1016/j.ceb.2016.03.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 11/20/2022]
Abstract
A polymer network of intranuclear lamin filaments underlies the nuclear envelope and provides mechanical stability to the nucleus in metazoans. Recent work demonstrates that the expression of A-type lamins scales positively with the stiffness of the cellular environment, thereby coupling nuclear and extracellular mechanics. Using the spectrin-actin network at the erythrocyte plasma membrane as a model, we contemplate how the relative stiffness of the nuclear scaffold impinges on the growing number of interphase-specific nuclear envelope remodeling events, including recently discovered, nuclear envelope-specialized quality control mechanisms. We suggest that a stiffer lamina impedes these remodeling events, necessitating local lamina remodeling and/or concomitant scaling of the efficacy of membrane-remodeling machineries that act at the nuclear envelope.
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21
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Closing a gap in the nuclear envelope. Curr Opin Cell Biol 2016; 40:90-97. [PMID: 27016712 DOI: 10.1016/j.ceb.2016.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/13/2016] [Accepted: 03/05/2016] [Indexed: 11/22/2022]
Abstract
The nuclear envelope (NE) ensures nucleo-cytoplasmic compartmentalization, with trafficking of macromolecules across this double membrane controlled by embedded nuclear pore complexes (NPCs). The NE and associated proteins are dismantled during open mitosis and reestablishment of this barrier during mitotic exit requires dynamic remodeling of endoplasmic reticulum (ER) membranes and coordination with NPC reformation, with NPC deposition continuing during subsequent interphase. In this review, we discuss recent progress in our understanding of NE reformation and nuclear pore complex generation, with special focus on work implicating the endosomal sorting complex required for transport (ESCRT) membrane remodeling machinery in these events.
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22
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Olmos Y, Carlton JG. The ESCRT machinery: new roles at new holes. Curr Opin Cell Biol 2016; 38:1-11. [PMID: 26775243 PMCID: PMC5023845 DOI: 10.1016/j.ceb.2015.12.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 12/14/2015] [Accepted: 12/21/2015] [Indexed: 01/04/2023]
Abstract
The ESCRT machinery drives a diverse collection of membrane remodeling events, including multivesicular body biogenesis, release of enveloped retroviruses and both reformation of the nuclear envelope and cytokinetic abscission during mitotic exit. These events share the requirement for a topologically equivalent membrane remodeling for their completion and the cells deployment of the ESCRT machinery in these different contexts highlights its functionality as a transposable membrane-fission machinery. Here, we will examine recent data describing ESCRT-III dependent membrane remodeling and explore new roles for the ESCRT-III complex at the nuclear envelope.
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Affiliation(s)
- Y Olmos
- Division of Cancer Studies, Section of Cell Biology and Imaging, King's College London, London SE1 1UL, United Kingdom
| | - J G Carlton
- Division of Cancer Studies, Section of Cell Biology and Imaging, King's College London, London SE1 1UL, United Kingdom.
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23
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Low-Rank and Sparse Matrix Decomposition for Genetic Interaction Data. BIOMED RESEARCH INTERNATIONAL 2015; 2015:573956. [PMID: 26273633 PMCID: PMC4529927 DOI: 10.1155/2015/573956] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/13/2015] [Indexed: 11/28/2022]
Abstract
Background. Epistatic miniarray profile (EMAP) studies have enabled the mapping of large-scale genetic interaction networks and generated large amounts of data in model organisms. One approach to analyze EMAP data is to identify gene modules with densely interacting genes. In addition, genetic interaction score (S score) reflects the degree of synergizing or mitigating effect of two mutants, which is also informative. Statistical approaches that exploit both modularity and the pairwise interactions may provide more insight into the underlying biology. However, the high missing rate in EMAP data hinders the development of such approaches. To address the above problem, we adopted the matrix decomposition methodology “low-rank and sparse decomposition” (LRSDec) to decompose EMAP data matrix into low-rank part and sparse part. Results. LRSDec has been demonstrated as an effective technique for analyzing EMAP data. We applied a synthetic dataset and an EMAP dataset studying RNA-related processes in Saccharomyces cerevisiae. Global views of the genetic cross talk between different RNA-related protein complexes and processes have been structured, and novel functions of genes have been predicted.
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24
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Kralt A, Jagalur NB, van den Boom V, Lokareddy RK, Steen A, Cingolani G, Fornerod M, Veenhoff LM. Conservation of inner nuclear membrane targeting sequences in mammalian Pom121 and yeast Heh2 membrane proteins. Mol Biol Cell 2015; 26:3301-12. [PMID: 26179916 PMCID: PMC4569319 DOI: 10.1091/mbc.e15-03-0184] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 07/08/2015] [Indexed: 12/23/2022] Open
Abstract
This study examines whether active transport to the inner nuclear membrane, as shown for yeast membrane proteins Heh1 and Heh2, is conserved in metazoans. In support of this, the nuclear localization signal of metazoan Pom121 shares biochemical, structural, and functional properties with those of Heh1 and Heh2, and a Heh2-derived reporter protein targets to the inner membrane in Hek293T cells. Endoplasmic reticulum–synthesized membrane proteins traffic through the nuclear pore complex (NPC) en route to the inner nuclear membrane (INM). Although many membrane proteins pass the NPC by simple diffusion, two yeast proteins, ScSrc1/ScHeh1 and ScHeh2, are actively imported. In these proteins, a nuclear localization signal (NLS) and an intrinsically disordered linker encode the sorting signal for recruiting the transport factors for FG-Nup and RanGTP-dependent transport through the NPC. Here we address whether a similar import mechanism applies in metazoans. We show that the (putative) NLSs of metazoan HsSun2, MmLem2, HsLBR, and HsLap2β are not sufficient to drive nuclear accumulation of a membrane protein in yeast, but the NLS from RnPom121 is. This NLS of Pom121 adapts a similar fold as the NLS of Heh2 when transport factor bound and rescues the subcellular localization and synthetic sickness of Heh2ΔNLS mutants. Consistent with the conservation of these NLSs, the NLS and linker of Heh2 support INM localization in HEK293T cells. The conserved features of the NLSs of ScHeh1, ScHeh2, and RnPom121 and the effective sorting of Heh2-derived reporters in human cells suggest that active import is conserved but confined to a small subset of INM proteins.
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Affiliation(s)
- Annemarie Kralt
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, Netherlands
| | - Noorjahan B Jagalur
- Departments of Biochemistry and Pediatric Oncology, Erasmus MC/Sophia, 3015 CN Rotterdam, Netherlands
| | - Vincent van den Boom
- Department of Experimental Hematology, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, Netherlands
| | - Ravi K Lokareddy
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Anton Steen
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, Netherlands
| | - Gino Cingolani
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107
| | - Maarten Fornerod
- Departments of Biochemistry and Pediatric Oncology, Erasmus MC/Sophia, 3015 CN Rotterdam, Netherlands
| | - Liesbeth M Veenhoff
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, 9713 AV Groningen, Netherlands )
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25
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The Inner Nuclear Membrane Protein Src1 Is Required for Stable Post-Mitotic Progression into G1 in Aspergillus nidulans. PLoS One 2015; 10:e0132489. [PMID: 26147902 PMCID: PMC4492595 DOI: 10.1371/journal.pone.0132489] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 06/15/2015] [Indexed: 01/13/2023] Open
Abstract
How membranes and associated proteins of the nuclear envelope (NE) are assembled specifically and inclusively around segregated genomes during exit from mitosis is incompletely understood. Inner nuclear membrane (INM) proteins play key roles by providing links between DNA and the NE. In this study we have investigated the highly conserved INM protein Src1 in Aspergillus nidulans and have uncovered a novel cell cycle response during post mitotic formation of G1 nuclei. Live cell imaging indicates Src1 could have roles during mitotic exit as it preferentially locates to the NE abscission points during nucleokinesis and to the NE surrounding forming daughter G1 nuclei. Deletion analysis further supported this idea revealing that although Src1 is not required for interphase progression or mitosis it is required for stable post-mitotic G1 nuclear formation. This conclusion is based upon the observation that in the absence of Src1 newly formed G1 nuclei are structurally unstable and immediately undergo architectural modifications typical of mitosis. These changes include NPC modifications that stop nuclear transport as well as disassembly of nucleoli. More intriguingly, the newly generated G1 nuclei then cycle between mitotic- and interphase-like states. The findings indicate that defects in post-mitotic G1 nuclear formation caused by lack of Src1 promote repeated failed attempts to generate stable G1 nuclei. To explain this unexpected phenotype we suggest a type of regulation that promotes repetition of defective cell cycle transitions rather than preventing progression past the defective cell cycle transition. We suggest the term “reboot regulation” to define this mode of cell cycle regulation. The findings are discussed in relationship to recent studies showing the Cdk1 master oscillator can entrain subservient oscillators that when uncoupled cause cell cycle transitions to be repeated.
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26
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The tethering of chromatin to the nuclear envelope supports nuclear mechanics. Nat Commun 2015; 6:7159. [PMID: 26074052 PMCID: PMC4490570 DOI: 10.1038/ncomms8159] [Citation(s) in RCA: 154] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 04/10/2015] [Indexed: 12/23/2022] Open
Abstract
The nuclear lamina is thought to be the primary mechanical defence of the nucleus. However, the lamina is integrated within a network of lipids, proteins and chromatin; the interdependence of this network poses a challenge to defining the individual mechanical contributions of these components. Here, we isolate the role of chromatin in nuclear mechanics by using a system lacking lamins. Using novel imaging analyses, we observe that untethering chromatin from the inner nuclear membrane results in highly deformable nuclei in vivo, particularly in response to cytoskeletal forces. Using optical tweezers, we find that isolated nuclei lacking inner nuclear membrane tethers are less stiff than wild-type nuclei and exhibit increased chromatin flow, particularly in frequency ranges that recapitulate the kinetics of cytoskeletal dynamics. We suggest that modulating chromatin flow can define both transient and long-lived changes in nuclear shape that are biologically important and may be altered in disease. The mechanical properties of the metazoan nucleus can be influenced by the nuclear lamina. Here, Schreiner et al. show that untethering chromatin from the inner nuclear membrane results in highly deformable, softer nuclei, revealing an important role for chromatin in modulating nuclear mechanics.
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27
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Lokareddy RK, Hapsari RA, van Rheenen M, Pumroy RA, Bhardwaj A, Steen A, Veenhoff LM, Cingolani G. Distinctive Properties of the Nuclear Localization Signals of Inner Nuclear Membrane Proteins Heh1 and Heh2. Structure 2015; 23:1305-1316. [PMID: 26051712 DOI: 10.1016/j.str.2015.04.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 04/23/2015] [Accepted: 04/23/2015] [Indexed: 01/13/2023]
Abstract
Targeting of ER-synthesized membrane proteins to the inner nuclear membrane (INM) has long been explained by the diffusion-retention model. However, several INM proteins contain non-classical nuclear localization signal (NLS) sequences, which, in a few instances, have been shown to promote importin α/β- and Ran-dependent translocation to the INM. Here, using structural and biochemical methods, we show that yeast INM proteins Heh2 and Src1/Heh1 contain bipartite import sequences that associate intimately with the minor NLS-binding pocket of yeast importin α and unlike classical NLSs efficiently displace the IBB domain in the absence of importin β. In vivo, the intimate interactions at the minor NLS-binding pocket make the h2NLS highly efficient at recruiting importin α at the ER and drive INM localization of endogenous Heh2. Thus, h1/h2NLSs delineate a novel class of super-potent, IBB-like membrane protein NLSs, distinct from classical NLSs found in soluble cargos and of general interest in biology.
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Affiliation(s)
- Ravi K Lokareddy
- Dept. of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10 Street, Philadelphia, PA 19107, USA
| | - Rizqiya A Hapsari
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands.,Zernike Institute for Advanced Materials, Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, Netherlands
| | - Mathilde van Rheenen
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Ruth A Pumroy
- Dept. of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10 Street, Philadelphia, PA 19107, USA
| | - Anshul Bhardwaj
- Dept. of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10 Street, Philadelphia, PA 19107, USA
| | - Anton Steen
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Liesbeth M Veenhoff
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, A. Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Gino Cingolani
- Dept. of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 South 10 Street, Philadelphia, PA 19107, USA
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28
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Abstract
The endosomal sorting complexes required for transport (ESCRT) are best known for their role in sorting ubiquitylated membrane proteins into endosomes. The most ancient component of the ESCRT machinery is ESCRT-III, which is capable of oligomerizing into a helical filament that drives the invagination and scission of membranes aided by the AAA ATPase, Vps4, in several additional subcellular contexts. Our recent study broadens the work of ESCRT-III by identifying its role in a quality control pathway at the nuclear envelope (NE) that ensures the normal biogenesis of nuclear pore complexes (NPCs). Here, we will elaborate on how we envision this mechanism to progress and incorporate ESCRT-III into an emerging model of nuclear pore formation. Moreover, we speculate there are additional roles for the ESCRT-III machinery at the NE that broadly function to ensure its integrity and the maintenance of the nuclear compartment.
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Key Words
- ERAD, ER-Associated Degradation
- ESCRT, Endosomal Sorting Complexes Required for Transport
- INM, Inner Nuclear Membrane
- LEM, Lap2, Emerin, MAN1
- MVB, Multivesicular Body
- NE, Nuclear Envelope
- NLS, Nuclear Localization Signal
- NPC, Nuclear Pore Complex
- ONM, Outer Nuclear Membrane
- SINC, Storage of Improperly assembled Nuclear pore Complexes
- endosomal sorting complex required for transport
- membrane curvature
- nuclear envelope
- nuclear pore complex
- quality control
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29
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Webster BM, Colombi P, Jäger J, Lusk CP. Surveillance of nuclear pore complex assembly by ESCRT-III/Vps4. Cell 2015; 159:388-401. [PMID: 25303532 DOI: 10.1016/j.cell.2014.09.012] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 07/07/2014] [Accepted: 09/04/2014] [Indexed: 12/19/2022]
Abstract
The maintenance of nuclear compartmentalization by the nuclear envelope and nuclear pore complexes (NPCs) is essential for cell function; loss of compartmentalization is associated with cancers, laminopathies, and aging. We uncovered a pathway that surveils NPC assembly intermediates to promote the formation of functional NPCs. Surveillance is mediated by Heh2, a member of the LEM (Lap2-emerin-MAN1) family of integral inner nuclear membrane proteins, which binds to an early NPC assembly intermediate, but not to mature NPCs. Heh2 recruits the endosomal sorting complex required for transport (ESCRT)-III subunit Snf7 and the AAA-ATPase Vps4 to destabilize and clear defective NPC assembly intermediates. When surveillance or clearance is compromised, malformed NPCs accumulate in a storage of improperly assembled nuclear pore complexes compartment, or SINC. The SINC is retained in old mothers to prevent loss of daughter lifespan, highlighting a continuum of mechanisms to ensure nuclear compartmentalization.
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Affiliation(s)
- Brant M Webster
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Paolo Colombi
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA
| | - Jens Jäger
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA
| | - C Patrick Lusk
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA.
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30
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Keilhauer EC, Hein MY, Mann M. Accurate protein complex retrieval by affinity enrichment mass spectrometry (AE-MS) rather than affinity purification mass spectrometry (AP-MS). Mol Cell Proteomics 2014; 14:120-35. [PMID: 25363814 PMCID: PMC4288248 DOI: 10.1074/mcp.m114.041012] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Protein–protein interactions are fundamental to the understanding of biological processes. Affinity purification coupled to mass spectrometry (AP-MS) is one of the most promising methods for their investigation. Previously, complexes were purified as much as possible, frequently followed by identification of individual gel bands. However, todays mass spectrometers are highly sensitive, and powerful quantitative proteomics strategies are available to distinguish true interactors from background binders. Here we describe a high performance affinity enrichment-mass spectrometry method for investigating protein–protein interactions, in which no attempt at purifying complexes to homogeneity is made. Instead, we developed analysis methods that take advantage of specific enrichment of interactors in the context of a large amount of unspecific background binders. We perform single-step affinity enrichment of endogenously expressed GFP-tagged proteins and their interactors in budding yeast, followed by single-run, intensity-based label-free quantitative LC-MS/MS analysis. Each pull-down contains around 2000 background binders, which are reinterpreted from troubling contaminants to crucial elements in a novel data analysis strategy. First the background serves for accurate normalization. Second, interacting proteins are not identified by comparison to a single untagged control strain, but instead to the other tagged strains. Third, potential interactors are further validated by their intensity profiles across all samples. We demonstrate the power of our AE-MS method using several well-known and challenging yeast complexes of various abundances. AE-MS is not only highly efficient and robust, but also cost effective, broadly applicable, and can be performed in any laboratory with access to high-resolution mass spectrometers.
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Affiliation(s)
- Eva C Keilhauer
- From the ‡Department Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Marco Y Hein
- From the ‡Department Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Matthias Mann
- From the ‡Department Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, Martinsried, Germany
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31
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Meinema AC, Poolman B, Veenhoff LM. The transport of integral membrane proteins across the nuclear pore complex. Nucleus 2014; 3:322-9. [DOI: 10.4161/nucl.20439] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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32
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Laba JK, Steen A, Veenhoff LM. Traffic to the inner membrane of the nuclear envelope. Curr Opin Cell Biol 2014; 28:36-45. [DOI: 10.1016/j.ceb.2014.01.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Revised: 01/17/2014] [Accepted: 01/19/2014] [Indexed: 11/27/2022]
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33
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Lusk CP, Colombi P. Toward a consensus on the mechanism of nuclear pore complex inheritance. Nucleus 2014; 5:97-102. [PMID: 24637838 DOI: 10.4161/nucl.28314] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Nuclear compartmentalization is achieved through the enclosure of the genome by the nuclear envelope; the nuclear envelope is perforated by nuclear pore complexes (NPCs), which form portals that control molecular exchange between the nucleus and cytoplasm. The number of NPCs per nucleus establishes a limit to the flux of molecules across the nuclear envelope and might directly impact genome organization and gene expression in a cell type specific manner. Mechanisms that control NPC number remain ill defined. Our recent study implicates a cytoplasmic pool of the nucleoporin Nsp1 as a factor that controls NPC number during the asymmetric division of budding yeast; Nsp1 acts to ensure that daughters inherit NPCs. We place our data within an emerging model of NPC inheritance in yeast and consider potential analogous mechanisms in multicellular eukaryotes, including the functional conservation of a cytoplasmic pool of Nsp1.
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Colombi P, Webster BM, Fröhlich F, Lusk CP. The transmission of nuclear pore complexes to daughter cells requires a cytoplasmic pool of Nsp1. ACTA ACUST UNITED AC 2013; 203:215-32. [PMID: 24165936 PMCID: PMC3812967 DOI: 10.1083/jcb.201305115] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Nuclear pore complexes (NPCs) are essential protein assemblies that span the nuclear envelope and establish nuclear-cytoplasmic compartmentalization. We have investigated mechanisms that control NPC number in mother and daughter cells during the asymmetric division of budding yeast. By simultaneously tracking existing NPCs and newly synthesized NPC protomers (nups) through anaphase, we uncovered a pool of the central channel nup Nsp1 that is actively targeted to the bud in association with endoplasmic reticulum. Bud targeting required an intact actin cytoskeleton and the class V myosin, Myo2. Selective inhibition of cytoplasmic Nsp1 or inactivation of Myo2 reduced the inheritance of NPCs in daughter cells, leading to a daughter-specific loss of viability. Our data are consistent with a model in which Nsp1 releases a barrier that otherwise prevents NPC passage through the bud neck. It further supports the finding that NPC inheritance, not de novo NPC assembly, is primarily responsible for controlling NPC number in daughter cells.
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Affiliation(s)
- Paolo Colombi
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
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35
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Walters AD, Cohen-Fix O. Nuclear division: giving daughters their fair share. Curr Biol 2013; 23:R1045-7. [PMID: 24309281 DOI: 10.1016/j.cub.2013.10.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
How do nuclear components, apart from chromosomes, partition equally to daughter nuclei during mitosis? In Schizosaccharomyces japonicus, the conserved LEM-domain nuclear envelope protein Man1 ensures the formation of identical daughter nuclei by coupling nuclear pore complexes to the segregating chromosomes.
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Affiliation(s)
- Alison D Walters
- The Laboratory of Cell and Molecular Biology, NIDDK, NIH, Bethesda, MD 20892, USA.
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36
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Partitioning and remodeling of the Schizosaccharomyces japonicus mitotic nucleus require chromosome tethers. Curr Biol 2013; 23:2303-2310. [PMID: 24184107 DOI: 10.1016/j.cub.2013.09.057] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 09/06/2013] [Accepted: 09/26/2013] [Indexed: 11/24/2022]
Abstract
During cellular proliferation, the mother nucleus divides into two daughters, each carrying a full complement of chromosomes and capable of driving the next cell cycle. Mitotic chromosome segregation must be coordinated with remodeling of other nuclear components, including the nuclear envelope (NE) and the non-membrane-bound nucleolus. Here, we show that in the fission yeast Schizosaccharomyces japonicus, which breaks and reforms the NE during mitosis, the evolutionary conserved LEM-domain protein Man1 promotes equal partitioning of the nuclear membrane, nucleolar remodeling, and efficient inheritance of the nuclear pore complexes (NPCs) by the daughter nuclei. Analyses of man1 mutants and results obtained using an artificial chromatin-nuclear pore tether suggest that Man1 may exert its function by linking the NPCs to segregating chromatin. By integrating the partitioning of the nuclear membrane and nucleolar material with chromosome segregation, cells build two nearly identical copies of the original nucleus.
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37
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Niepel M, Molloy KR, Williams R, Farr JC, Meinema AC, Vecchietti N, Cristea IM, Chait BT, Rout MP, Strambio-De-Castillia C. The nuclear basket proteins Mlp1p and Mlp2p are part of a dynamic interactome including Esc1p and the proteasome. Mol Biol Cell 2013; 24:3920-38. [PMID: 24152732 PMCID: PMC3861087 DOI: 10.1091/mbc.e13-07-0412] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mlp1p and Mlp2p form the basket of the yeast nuclear pore complex (NPC) and contribute to NPC positioning, nuclear stability, and nuclear envelope morphology. The Mlps also embed the NPC within an extended interactome, which includes protein complexes involved in mRNP biogenesis, silencing, spindle organization, and protein degradation. The basket of the nuclear pore complex (NPC) is generally depicted as a discrete structure of eight protein filaments that protrude into the nucleoplasm and converge in a ring distal to the NPC. We show that the yeast proteins Mlp1p and Mlp2p are necessary components of the nuclear basket and that they also embed the NPC within a dynamic protein network, whose extended interactome includes the spindle organizer, silencing factors, the proteasome, and key components of messenger ribonucleoproteins (mRNPs). Ultrastructural observations indicate that the basket reduces chromatin crowding around the central transporter of the NPC and might function as a docking site for mRNP during nuclear export. In addition, we show that the Mlps contribute to NPC positioning, nuclear stability, and nuclear envelope morphology. Our results suggest that the Mlps are multifunctional proteins linking the nuclear transport channel to multiple macromolecular complexes involved in the regulation of gene expression and chromatin maintenance.
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Affiliation(s)
- Mario Niepel
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115 Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, New York, NY 10065 Laboratory of Cellular and Structural Biology, Rockefeller University, New York, NY 10065 Institute for Research in Biomedicine, 6500 Bellinzona, Switzerland Istituto Cantonale di Microbiologia, 6500 Bellinzona, Switzerland Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605
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38
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Poring over pores: nuclear pore complex insertion into the nuclear envelope. Trends Biochem Sci 2013; 38:292-301. [DOI: 10.1016/j.tibs.2013.04.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Revised: 03/29/2013] [Accepted: 04/02/2013] [Indexed: 11/18/2022]
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39
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Meinema AC, Poolman B, Veenhoff LM. Quantitative Analysis of Membrane Protein Transport Across the Nuclear Pore Complex. Traffic 2013; 14:487-501. [DOI: 10.1111/tra.12048] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 01/22/2013] [Accepted: 01/28/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Anne C. Meinema
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, Netherlands Proteomics Centre, Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4; 9747 AG; Groningen; the Netherlands
| | - Bert Poolman
- Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, Netherlands Proteomics Centre, Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4; 9747 AG; Groningen; the Netherlands
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40
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Jaspersen SL, Ghosh S. Nuclear envelope insertion of spindle pole bodies and nuclear pore complexes. Nucleus 2012; 3:226-36. [PMID: 22572959 PMCID: PMC3414398 DOI: 10.4161/nucl.20148] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The defining feature of eukaryotic cells is the double lipid bilayer of the nuclear envelope (NE) that serves as a physical barrier separating the genome from the cytosol. Nuclear pore complexes (NPCs) are embedded in the NE to facilitate transport of proteins and other macromolecules into and out of the nucleus. In fungi and early embryos where the NE does not completely breakdown during mitosis, microtubule-organizing centers such as the spindle pole body (SPB) must also be inserted into the NE to facilitate organization of the mitotic spindle. Several recent papers have shed light on the mechanism by which SPB complexes are inserted into the NE. An unexpected link between the SPB and NPCs suggests that assembly of these NE complexes is tightly coordinated. We review the findings of these reports in light of our current knowledge of SPB, NPC and NE structure, assembly and function.
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Affiliation(s)
- Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, MO, USA.
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41
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Abstract
The nuclear envelope in eukaryotic cells has important roles in chromatin organization. The inner nuclear membrane contains over 60 transmembrane proteins. LEM [LAP2 (lamina-associated polypeptide 2)/emerin/MAN1] domain-containing proteins of the inner nuclear membrane are involved in tethering chromatin to the nuclear envelope and affect gene expression. They contain a common structural, bihelical motif, the so-called LEM domain, which mediates binding to a conserved chromatin protein, BAF (barrier to autointegration factor). Interestingly, this domain is highly related to other bihelical motifs, termed HeH (helix-extension-helix) and SAP {SAF (scaffold attachment factor)/acinus/PIAS [protein inhibitor of activated STAT (signal transducer and activator of transcription)]} motifs, which are directly linked to DNA. In the present paper, we summarize evidence that the LEM motif evolved from the HeH and SAP domains concomitantly with BAF. In addition, we discuss the potential evolution of HeH/SAP and LEM domain-containing proteins and their role in chromatin tethering and gene regulation from unicellular eukaryotes to mammals.
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42
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Clever M, Funakoshi T, Mimura Y, Takagi M, Imamoto N. The nucleoporin ELYS/Mel28 regulates nuclear envelope subdomain formation in HeLa cells. Nucleus 2012; 3:187-99. [PMID: 22555603 PMCID: PMC3383574 DOI: 10.4161/nucl.19595] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
In open mitosis the nuclear envelope (NE) reassembles at the end of each mitosis. This process involves the reformation of the nuclear pore complex (NPC), the inner and outer nuclear membranes, and the nuclear lamina. In human cells cell cycle-dependent NE subdomains exist, characterized as A-type lamin-rich/NPC-free or B-type lamin-rich/NPC-rich, which are initially formed as core or noncore regions on mitotic chromosomes, respectively. Although postmitotic NE formation has been extensively studied, little is known about the coordination of NPC and NE assembly. Here, we report that the nucleoporin ELYS/Mel28, which is crucial for postmitotic NPC formation, is essential for recruiting the lamin B receptor (LBR) to the chromosomal noncore region. Furthermore, ELYS/Mel28 is responsible for focusing of A-type lamin-binding proteins like emerin, Lap2α and the barrier-to-autointegration factor (BAF) at the chromosomal core region. ELYS/Mel28 biochemically interacts with the LBR in a phosphorylation-dependent manner. Recruitment of the LBR depends on the nucleoporin Nup107, which interacts with ELYS/Mel28 but not on nucleoporin Pom121, suggesting that the specific molecular interactions with ELYS/Mel28 are involved in the NE assembly at the noncore region. The depletion of the LBR affected neither the behavior of emerin nor Lap2α indicating that the recruitment of the LBR to mitotic chromosomes is not involved in formation of the core region. The depletion of ELYS/Mel28 also accelerates the entry into cytokinesis after recruitment of emerin to chromosomes. Our data show that ELYS/Mel28 plays a role in NE subdomain formation in late mitosis.
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Affiliation(s)
- Michaela Clever
- Cellular Dynamics Laboratory; Riken Advanced Science Institute; Saitama, Japan
| | - Tomoko Funakoshi
- Cellular Dynamics Laboratory; Riken Advanced Science Institute; Saitama, Japan
- Live-Cell Molecular Imaging Research Team; Riken Advanced Science Institute; Saitama, Japan
| | - Yasuhiro Mimura
- Cellular Dynamics Laboratory; Riken Advanced Science Institute; Saitama, Japan
| | - Masatoshi Takagi
- Cellular Dynamics Laboratory; Riken Advanced Science Institute; Saitama, Japan
| | - Naoko Imamoto
- Cellular Dynamics Laboratory; Riken Advanced Science Institute; Saitama, Japan
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43
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Burns LT, Wente SR. Trafficking to uncharted territory of the nuclear envelope. Curr Opin Cell Biol 2012; 24:341-9. [PMID: 22326668 DOI: 10.1016/j.ceb.2012.01.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 01/20/2012] [Accepted: 01/23/2012] [Indexed: 02/07/2023]
Abstract
The nuclear envelope (NE) in eukaryotic cells serves as the physical barrier between the nucleus and cytoplasm. Until recently, mechanisms for establishing the composition of the inner nuclear membrane (INM) remained uncharted. Current findings uncover multiple pathways for trafficking of integral and peripheral INM proteins. A major route for INM protein transport occurs through the nuclear pore complexes (NPCs) with additional requirements for nuclear localization sequences, transport receptors, and Ran-GTP. Studies also reveal a putative NPC-independent vesicular pathway for NE trafficking. INM perturbations lead to changes in nuclear physiology highlighting the potential human disease impacts of continued NE discoveries.
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Affiliation(s)
- Laura T Burns
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, United States
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44
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Gonzalez Y, Saito A, Sazer S. Fission yeast Lem2 and Man1 perform fundamental functions of the animal cell nuclear lamina. Nucleus 2012; 3:60-76. [PMID: 22540024 PMCID: PMC3337167 DOI: 10.4161/nucl.18824] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
In animal cells the nuclear lamina, which consists of lamins and lamin-associated proteins, serves several functions: it provides a structural scaffold for the nuclear envelope and tethers proteins and heterochromatin to the nuclear periphery. In yeast, proteins and large heterochromatic domains including telomeres are also peripherally localized, but there is no evidence that yeast have lamins or a fibrous nuclear envelope scaffold. Nonetheless, we found that the Lem2 and Man1 proteins of the fission yeast Schizosaccharomyces pombe, evolutionarily distant relatives of the Lap2/Emerin/Man1 (LEM) sub-family of animal cell lamin-associated proteins, perform fundamental functions of the animal cell lamina. These integral inner nuclear membrane localized proteins, with nuclear localized DNA binding Helix-Extension-Helix (HEH) domains, impact nuclear envelope structure and integrity, are essential for the enrichment of telomeres at the nuclear periphery and by means of their HEH domains anchor chromatin, most likely transcriptionally repressed heterochromatin, to the nuclear periphery. These data indicate that the core functions of the nuclear lamina are conserved between fungi and animal cells and can be performed in fission yeast, without lamins or other intermediate filament proteins.
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Affiliation(s)
- Yanira Gonzalez
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology; Baylor College of Medicine; Houston, TX USA
| | - Akira Saito
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology; Baylor College of Medicine; Houston, TX USA
| | - Shelley Sazer
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology; Baylor College of Medicine; Houston, TX USA
- Department of Molecular and Cellular Biology; Baylor College of Medicine; Houston, TX USA
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45
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Chan JNY, Poon BPK, Salvi J, Olsen JB, Emili A, Mekhail K. Perinuclear cohibin complexes maintain replicative life span via roles at distinct silent chromatin domains. Dev Cell 2011; 20:867-79. [PMID: 21664583 DOI: 10.1016/j.devcel.2011.05.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 03/24/2011] [Accepted: 05/18/2011] [Indexed: 10/18/2022]
Abstract
Heterochromatin, or silent chromatin, preferentially resides at the nuclear envelope. Telomeres and rDNA repeats are the two major perinuclear silent chromatin domains of Saccharomyces cerevisiae. The Cohibin protein complex maintains rDNA repeat stability in part through silent chromatin assembly and perinuclear rDNA anchoring. We report here a role for Cohibin at telomeres and show that functions of the complex at chromosome ends and rDNA maintain replicative life span. Cohibin binds LEM/SUN domain-containing nuclear envelope proteins and telomere-associated factors. Disruption of Cohibin or the envelope proteins abrogates telomere localization and silent chromatin assembly within subtelomeres. Loss of Cohibin limits Sir2 histone deacetylase localization to chromosome ends, disrupts subtelomeric DNA stability, and shortens life span even when rDNA repeats are stabilized. Restoring telomeric Sir2 concentration abolishes chromatin and life span defects linked to the loss of telomeric Cohibin. Our work uncovers roles for Cohibin complexes and reveals relationships between nuclear compartmentalization, chromosome stability, and aging.
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Affiliation(s)
- Janet N Y Chan
- Department of Laboratory Medicine and Pathobiology, University of Toronto, ON, Canada
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