Nuclear envelope-vacuole contacts mitigate nuclear pore complex assembly stress

AbstractThe intricacy of nuclear pore complex (NPC) biogenesis imposes risks of failure that can cause defects in nuclear transport and nuclear envelope morphology, however, cellular mechanisms utilized to alleviate NPC assembly stress are not well-defined. In the budding yeast Saccharomyces cerevisiae, we demonstrate that NVJ1- and MDM1-enriched nuclear envelope (NE)-vacuole contacts increase when NPC assembly is compromised in several nup mutants, including nup116ΔGLFG cells. These interorganelle nucleus-vacuole junctions (NVJs) cooperate with lipid droplets to maintain viability and enhance NPC formation in assembly mutants. Additionally, NVJs function with ATG1 to promote vacuole-dependent remodeling in nup116ΔGLFG cells, which also correlates with proper NPC formation. Importantly, NVJs significantly improve the physiology of NPC assembly mutants, despite having only negligible effects when NPC biogenesis is unperturbed. Collectively, these results define how NE-vacuole interorganelle contacts coordinate responses to mitigate deleterious cellular effects caused by disrupted NPC assembly.SummaryHow cells respond to deleterious effects imposed by disrupted nuclear pore complex (NPC) assembly are not well-defined. The authors demonstrate nuclear envelope-vacuole interactions expand in response to perturbed NPC assembly to promote viability, nuclear envelope remodeling, and proper NPC biogenesis.

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Nuclear envelope–vacuole contacts mitigate nuclear pore complex assembly stress

The Journal of Cell Biology ◽

10.1083/jcb.202001165 ◽

2020 ◽

Vol 219 (12) ◽

Author(s):

Christopher L. Lord ◽

Susan R. Wente

Keyword(s):

Saccharomyces Cerevisiae ◽

Nuclear Envelope ◽

Nuclear Pore Complex ◽

Lipid Droplets ◽

Budding Yeast ◽

Nuclear Pore ◽

Cellular Mechanisms ◽

Yeast Saccharomyces Cerevisiae ◽

Complex Assembly ◽

Cellular Effects

The intricacy of nuclear pore complex (NPC) biogenesis imposes risks of failure that can cause defects in nuclear transport and nuclear envelope (NE) morphology; however, cellular mechanisms used to alleviate NPC assembly stress are not well defined. In the budding yeast Saccharomyces cerevisiae, we demonstrate that NVJ1- and MDM1-enriched NE–vacuole contacts increase when NPC assembly is compromised in several nup mutants, including nup116ΔGLFG cells. These interorganelle nucleus–vacuole junctions (NVJs) cooperate with lipid droplets to maintain viability and enhance NPC formation in assembly mutants. Additionally, NVJs function with ATG1 to remodel the NE and promote vacuole-dependent degradation of specific nucleoporins in nup116ΔGLFG cells. Importantly, NVJs significantly improve the physiology of NPC assembly mutants, despite having only negligible effects when NPC biogenesis is unperturbed. These results therefore define how NE–vacuole interorganelle contacts coordinate responses to mitigate deleterious cellular effects caused by disrupted NPC assembly.

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The nucleoporins Nup170p and Nup157p are essential for nuclear pore complex assembly

The Journal of Cell Biology ◽

10.1083/jcb.200810029 ◽

2009 ◽

Vol 185 (3) ◽

pp. 459-473 ◽

Cited By ~ 54

Author(s):

Tadashi Makio ◽

Leslie H. Stanton ◽

Cheng-Chao Lin ◽

David S. Goldfarb ◽

Karsten Weis ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Nuclear Pore Complex ◽

Nuclear Membrane ◽

Essential Role ◽

Nuclear Transport ◽

Nuclear Pore ◽

Nuclear Pore Complexes ◽

Complex Assembly ◽

Cytoplasmic Face ◽

Pore Complexes

We have established that two homologous nucleoporins, Nup170p and Nup157p, play an essential role in the formation of nuclear pore complexes (NPCs) in Saccharomyces cerevisiae. By regulating their synthesis, we showed that the loss of these nucleoporins triggers a decrease in NPCs caused by a halt in new NPC assembly. Preexisting NPCs are ultimately lost by dilution as cells grow, causing the inhibition of nuclear transport and the loss of viability. Significantly, the loss of Nup170p/Nup157p had distinct effects on the assembly of different architectural components of the NPC. Nucleoporins (nups) positioned on the cytoplasmic face of the NPC rapidly accumulated in cytoplasmic foci. These nup complexes could be recruited into new NPCs after reinitiation of Nup170p synthesis, and may represent a physiological intermediate. Loss of Nup170p/Nup157p also caused core and nucleoplasmically positioned nups to accumulate in NPC-like structures adjacent to the inner nuclear membrane, which suggests that these nucleoporins are required for formation of the pore membrane and the incorporation of cytoplasmic nups into forming NPCs.

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Faculty Opinions recommendation of The integral membrane nucleoporin pom121 functionally links nuclear pore complex assembly and nuclear envelope formation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1023280.285732 ◽

2005 ◽

Author(s):

Mary Dasso

Keyword(s):

Nuclear Envelope ◽

Nuclear Pore Complex ◽

Nuclear Pore ◽

Complex Assembly ◽

Nuclear Envelope Formation

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Regulation and coordination of nuclear envelope and nuclear pore complex assembly

Nucleus ◽

10.4161/nucl.23796 ◽

2013 ◽

Vol 4 (2) ◽

pp. 105-114 ◽

Cited By ~ 15

Author(s):

Michaela Clever ◽

Yasuhiro Mimura ◽

Tomoko Funakoshi ◽

Naoko Imamoto

Keyword(s):

Nuclear Envelope ◽

Nuclear Pore Complex ◽

Nuclear Pore ◽

Complex Assembly

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The Torsin/ NEP1R1-CTDNEP1/ Lipin axis regulates nuclear envelope lipid metabolism for nuclear pore complex insertion

10.1101/2020.07.05.188599 ◽

2020 ◽

Author(s):

Julie Jacquemyn ◽

Joyce Foroozandeh ◽

Katlijn Vints ◽

Jef Swerts ◽

Patrik Verstreken ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Nuclear Envelope ◽

Nuclear Pore Complex ◽

Lipid Droplets ◽

Nuclear Pore ◽

List Type ◽

Unknown Mechanism ◽

Structure Lipid ◽

Cellular Events ◽

Upstream Regulator

AbstractTorsin ATPases of the endoplasmic reticulum (ER) and nuclear envelope (NE) lumen inhibit Lipin-mediated phosphatidate (PA) to diacylglycerol (DAG) conversion by an unknown mechanism. This excess PA metabolism is implicated in TOR1A/TorsinA diseases, but it is unclear whether it explains why Torsin concomitantly affects nuclear structure, lipid droplets (LD), organelle and cell growth. Here a fly miniscreen identified that Torsins affect these events via the NEP1R1-CTDNEP1 phosphatase complex. Further, Torsin homo-oligomerization rather than ATPase activity was key to function. NEP1R1-CTDNEP1 activates Lipin by dephosphorylation. We show that Torsin prevents CTDNEP1 from accumulating in the NE and excludes Lipin from the nucleus. Moreover, this repression of nuclear PA metabolism is required for interphase nuclear pore biogenesis. We conclude that Torsin is an upstream regulator of the NEP1R1-CTDNEP1/ Lipin pathway. This connects the ER/NE lumen with PA metabolism, and affects numerous cellular events including it has a previously unrecognized role in nuclear pore biogenesis.HighlightsNuclear envelope PA-DAG-TAG synthesis is independently regulated by Torsin and Torip/LAP1Torsin removes CTDNEP1 from the nuclear envelope and excludes Lipin from the nucleusExcess nuclear envelope NEP1R1-CTDNEP1/ Lipin activity impairs multiple aspects of NPC biogenesisNEP1R1-CTDNEP1/ Lipin inhibition prevents cellular defects associated with TOR1A and TOR1AIP1 / LAP1 disease

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GLE2, a Saccharomyces cerevisiae homologue of the Schizosaccharomyces pombe export factor RAE1, is required for nuclear pore complex structure and function.

Molecular Biology of the Cell ◽

10.1091/mbc.7.12.1921 ◽

1996 ◽

Vol 7 (12) ◽

pp. 1921-1937 ◽

Cited By ~ 119

Author(s):

R Murphy ◽

J L Watkins ◽

S R Wente

Keyword(s):

Saccharomyces Cerevisiae ◽

Schizosaccharomyces Pombe ◽

Nuclear Pore Complex ◽

Nuclear Export ◽

Protein Import ◽

Nuclear Transport ◽

Complex Structure ◽

Striking Similarity ◽

Nuclear Pore ◽

Pore Complexes

To identify and characterize novel factors required for nuclear transport, a genetic screen was conducted in the yeast Saccharomyces cerevisiae. Mutations that were lethal in combination with a null allele of the gene encoding the nucleoporin Nup100p were isolated using a colony-sectoring assay. Three complementation groups of gle (for GLFG lethal) mutants were identified. In this report, the characterization of GLE2 is detailed. GLE2 encodes a 40.5-kDa polypeptide with striking similarity to that of Schizosaccharomyces pombe RAE1. In indirect immunofluorescence and nuclear pore complex fractionation experiments, Gle2p was associated with nuclear pore complexes. Mutated alleles of GLE2 displayed blockage of polyadenylated RNA export; however, nuclear protein import was not apparently diminished. Immunofluorescence and thin-section electron microscopic analysis revealed that the nuclear pore complex and nuclear envelope structure was grossly perturbed in gle2 mutants. Because the clusters of herniated pore complexes appeared subsequent to the export block, the structural perturbations were likely indirect consequences of the export phenotype. Interestingly, a two-hybrid interaction was detected between Gle2p and Srp1p, the nuclear localization signal receptor, as well as Rip1p, a nuclear export signal-interacting protein. We propose that Gle2p has a novel role in mediating nuclear transport.

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Piecing together nuclear pore complex assembly during interphase

The Journal of Cell Biology ◽

10.1083/jcb.200904022 ◽

2009 ◽

Vol 185 (3) ◽

pp. 377-379 ◽

Cited By ~ 9

Author(s):

Michael Rexach

Keyword(s):

Nuclear Envelope ◽

Nuclear Pore Complex ◽

Supramolecular Structures ◽

Nuclear Pore ◽

Nuclear Pore Complexes ◽

Assembly Process ◽

Nuclear Pores ◽

Complex Assembly ◽

Cell Biol ◽

Pore Complexes

All nucleocytoplasmic traffic of macromolecules occurs through nuclear pore complexes (NPCs), which function as stents in the nuclear envelope to keep nuclear pores open but gated. Three studies in this issue (Flemming, D., P. Sarges, P. Stelter, A. Hellwig, B. Böttcher, and E. Hurt. 2009. J. Cell Biol. 185:387–395; Makio, T., L.H. Stanton, C.-C. Lin, D.S. Goldfarb, K. Weis, and R.W. Wozniak. 2009. J. Cell Biol. 185:459–491; Onishchenko, E., L.H. Stanton, A.S. Madrid, T. Kieselbach, and K. Weis. 2009. J. Cell Biol. 185:475–491) further our understanding of the NPC assembly process by reporting what happens when the supply lines of key proteins that provide a foundation for building these marvelous supramolecular structures are disrupted.

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