Developmental Genetics of the Essential Drosophila Nucleoporin nup154: Allelic Differences Due to an Outward-Directed Promoter in the P-Element 3′ End

Abstract Drosophila nup154 encodes a predicted nucleoporin homologous to yeast Nup170p, Nup157p, and vertebrate Nup155, all of which are major components of the nuclear pore complex (NPC). Unlike its yeast homologs, nup154 is essential for viability. Animals with strong loss-of-function nup154 mutations caused by P-element insertion in the 5′-UTR of the gene died as larvae with small discs, brains, and testes. nup154 mRNA expression appeared developmentally regulated in tissues of wild-type embryos, larvae, and adults, suggesting that new nup154 synthesis is required when assembly of new NPCs is required, as in proliferating or growing tissues. Two additional nup154 alleles also associated with different P-element inserts in the 5′-UTR were viable but had strong loss-of-function sterile phenotypes, including failure to maintain spermatogenic stem cells and failure to progress into vitellogenic stages of oogenesis. Lethality vs. viability correlated with orientation of the P-element inserts in the different alleles. Transcript analysis by 5′-RACE suggested a mechanism for allelic differences: an outward-directed promoter internal to the P-element 3′ end able to drive sufficient expression of the nup154 transcript for viability but not for fertility.

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The single transmembrane segment of gp210 is sufficient for sorting to the pore membrane domain of the nuclear envelope.

The Journal of Cell Biology ◽

10.1083/jcb.119.6.1441 ◽

1992 ◽

Vol 119 (6) ◽

pp. 1441-1449 ◽

Cited By ~ 75

Author(s):

R W Wozniak ◽

G Blobel

Keyword(s):

Nuclear Envelope ◽

Nuclear Pore Complex ◽

Immunofluorescence Microscopy ◽

Nuclear Pore ◽

Transmembrane Helices ◽

Wild Type ◽

Transmembrane Segment ◽

Membrane Domain ◽

3T3 Cells ◽

Type Mutant

The glycoprotein gp210 is located in the "pore membrane," a specialized domain of the nuclear envelope to which the nuclear pore complex (NPC) is anchored. gp210 contains a large cisternal domain, a single transmembrane segment (TM), and a COOH-terminal, 58-amino acid residue cytoplasmic tail (CT) (Wozniak, R. W., E. Bartnik, and G. Blobel. 1989. J. Cell Biol. 108:2083-2092; Greber, U. F., A. Senior, and L. Gerace. 1990. EMBO (Eur. Mol. Biol. Organ.) J. 9:1495-1502). To locate determinants for sorting of gp210 to the pore membrane, we constructed various cDNAs coding for wild-type, mutant, and chimeric gp210, and monitored localization of the expressed protein in 3T3 cells by immunofluorescence microscopy using appropriate antibodies. The large cisternal domain of gp210 (95% of its mass) did not reveal any sorting determinants. Surprisingly, the TM of gp210 is sufficient for sorting to the pore membrane. The CT also contains a sorting determinant, but it is weaker than that of the TM. We propose specific lateral association of the transmembrane helices of two proteins to yield either a gp210 homodimer or a heterodimer of gp210 and another protein. The cytoplasmically oriented tails of these dimers may bind cooperatively to the adjacent NPCs. In addition, we demonstrate that gp210 co-localizes with cytoplasmically dispersed nucleoporins, suggesting a cytoplasmic association of these components.

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Binding Dynamics of Structural Nucleoporins Govern Nuclear Pore Complex Permeability and May Mediate Channel Gating

Molecular and Cellular Biology ◽

10.1128/mcb.23.2.534-542.2003 ◽

2003 ◽

Vol 23 (2) ◽

pp. 534-542 ◽

Cited By ~ 72

Author(s):

Nataliya Shulga ◽

David S. Goldfarb

Keyword(s):

Nuclear Pore Complex ◽

Size Range ◽

Channel Gating ◽

Aliphatic Alcohols ◽

Complex Permeability ◽

Nuclear Pore ◽

Wild Type ◽

Unknown Mechanism ◽

Reversible Dissociation ◽

Wide Size Range

ABSTRACT The nuclear pore complex (NPC) is a permeable sieve that can dilate to facilitate the bidirectional translocation of a wide size range of receptor-cargo complexes. The binding of receptors to FG nucleoporin docking sites triggers channel gating by an unknown mechanism. Previously, we used deoxyglucose and chilling treatments to implicate Nup170p and Nup188p in the control of NPC sieving in Saccharomyces cerevisiae. Here, we report that aliphatic alcohols increase the permeability of wild-type and nup170Δ NPCs. In conjunction with increases in permeability, aliphatic alcohols, deoxyglucose, and chilling trigger the reversible dissociation of several nucleoporins from nup170Δ NPCs. These results are consistent with the hypothesis that NPC gating occurs when molecular latches composed of FG repeats and structural nucleoporins dissociate.

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Two Nucleoporin98 homologous genes jointly participate in the regulation of starch degradation to repress senescence in Arabidopsis

10.21203/rs.2.21484/v4 ◽

2020 ◽

Author(s):

Long Xiao ◽

Shanshan Jiang ◽

Penghui Huang ◽

Fulu Chen ◽

Xu Wang ◽

...

Keyword(s):

Energy Metabolism ◽

Nuclear Pore Complex ◽

Growth And Development ◽

Double Mutant ◽

Growth Regulation ◽

Sugar Metabolism ◽

Starch Degradation ◽

Marker Genes ◽

Nuclear Pore ◽

Wild Type

Abstract Background: Starch is synthesized during the day for temporary storage in leaves and then degraded during the subsequent night to support plant growth and development. Impairment of starch degradation leads to stunted growth, even senescence and death. The nuclear pore complex is involved in many cellular processes, but its relationship with starch degradation is unclear until now. We previously identified that two Nucleoporin98 (Nup98) genes (Nup98a and Nup98b) redundantly regulate flowering through CONSTANS (CO) independent pathway in Arabidopsis thaliana. The nup98a-1 nup98b-1 double mutant also shows severe senescence phenotypes. Results: We find that Nucleoporin 98 (Nup98) participates in the regulation of sugar metabolism in leaves and in turn involves in senescence regulation in Arabidopsis. We show that Nup98a and Nup98b redundantly function in the different steps of starch degradation and the nup98a-1 nup98b-1 double mutant accumulates more starch than wild type plants and has a severe early senescence phenotype compared to wild type plants. The expression of marker genes related to starch degradation is impaired in the nup98a-1 nup98b-1 double mutant, and marker genes of carbon starvation and senescence express earlier and in higher abundance in the nup98a-1 nup98b-1 double mutant than in wild type plants, suggesting that abnormality of energy metabolism is the main cause of senescence of the nup98a-1 nup98b-1 double mutant. Addition of sucrose to the growth medium rescues early senescence phenotypes of the nup98a-1 nup98b-1 mutant. Conclusions: Our results provide a line of evidence on a novel role of the nuclear pore complex in energy metabolism related to growth and development, in which Nup98 functions in starch degradation conferring growth regulation in Arabidopsis.

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Two Nucleoporin98 homologous genes jointly participate in the regulation of starch degradation to repress senescence in Arabidopsis

10.21203/rs.2.21484/v5 ◽

2020 ◽

Author(s):

Long Xiao ◽

Shanshan Jiang ◽

Penghui Huang ◽

Fulu Chen ◽

Xu Wang ◽

...

Keyword(s):

Energy Metabolism ◽

Nuclear Pore Complex ◽

Growth And Development ◽

Double Mutant ◽

Growth Regulation ◽

Sugar Metabolism ◽

Starch Degradation ◽

Marker Genes ◽

Nuclear Pore ◽

Wild Type

Abstract Background: Starch is synthesized during daylight for temporary storage in leaves and then degraded during the subsequent night to support plant growth and development. Impairment of starch degradation leads to stunted growth, even senescence and death. The nuclear pore complex is involved in many cellular processes, but its relationship with starch degradation has been unclear until now. We previously identified that two Nucleoporin98 genes (Nup98a and Nup98b) redundantly regulate flowering via the CONSTANS (CO)-independent pathway in Arabidopsis thaliana. The double mutant also shows severe senescence phenotypes. Results: We find that Nucleoporin 98 participates in the regulation of sugar metabolism in leaves and is also involved in senescence regulation in Arabidopsis. We show that Nup98a and Nup98b function redundantly at different stages of starch degradation. The nup98a-1 nup98b-1 double mutant accumulates more starch, showing a severe early senescence phenotype compared to wild type plants. The expression of marker genes related to starch degradation is impaired in the nup98a-1 nup98b-1 double mutant, and marker genes of carbon starvation and senescence express their products earlier and in higher abundance than in wild type plants, suggesting that abnormalities in energy metabolism are the main cause of senescence in the double mutant. Addition of sucrose to the growth medium rescues early senescence phenotypes of the nup98a-1 nup98b-1 mutant. Conclusions: Our results provide evidence for a novel role of the nuclear pore complex in energy metabolism related to growth and development, in which Nup98 functions in starch degradation to control growth regulation in Arabidopsis.

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A nuclear export sequence promotes CRM1-dependent targeting of the nucleoporin Nup214 to the nuclear pore complex

Journal of Cell Science ◽

10.1242/jcs.258095 ◽

2021 ◽

Vol 134 (6) ◽

Author(s):

Mohamed Hamed ◽

Birgit Caspar ◽

Sarah A. Port ◽

Ralph H. Kehlenbach

Keyword(s):

Nuclear Pore Complex ◽

Nuclear Export ◽

Nuclear Pore ◽

Wild Type ◽

Leptomycin B ◽

Nuclear Export Sequence ◽

Binding Partners ◽

Dependent Protein ◽

Nuclear Export Receptor ◽

Cytoplasmic Side

ABSTRACT Nup214 is a major nucleoporin on the cytoplasmic side of the nuclear pore complex with roles in late steps of nuclear protein and mRNA export. It interacts with the nuclear export receptor CRM1 (also known as XPO1) via characteristic phenylalanine-glycine (FG) repeats in its C-terminal region. Here, we identify a classic nuclear export sequence (NES) in Nup214 that mediates Ran-dependent binding to CRM1. Nup214 versions with mutations in the NES, as well as wild-type Nup214 in the presence of the selective CRM1 inhibitor leptomycin B, accumulate in the nucleus of Nup214-overexpressing cells. Furthermore, physiological binding partners of Nup214, such as Nup62 and Nup88, are recruited to the nucleus together with Nup214. Nuclear export of mutant Nup214 can be rescued by artificial nuclear export sequences at the C-terminal end of Nup214, leading also to a correct localization of Nup88. Our results suggest a function of the Nup214 NES in the biogenesis of the nuclear pore complex and/or in terminal steps of CRM1-dependent protein export.

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The Karyopherin Kap95 Regulates Nuclear Pore Complex Assembly into Intact Nuclear Envelopes In Vivo

Molecular Biology of the Cell ◽

10.1091/mbc.e06-06-0525 ◽

2007 ◽

Vol 18 (3) ◽

pp. 886-898 ◽

Cited By ~ 33

Author(s):

Kathryn J. Ryan ◽

Yingna Zhou ◽

Susan R. Wente

Keyword(s):

Nuclear Pore Complex ◽

Protein Interactions ◽

De Novo ◽

Nuclear Pore ◽

Loss Of Function ◽

Spatial Cues ◽

Ran Gtpase ◽

Cytoplasmic Vesicles ◽

Cytoplasmic Membranes

Nuclear pore complex (NPC) assembly in interphase cells requires that new NPCs insert into an intact nuclear envelope (NE). Our previous work identified the Ran GTPase as an essential component in this process. We proposed that Ran is required for targeting assembly factors to the cytoplasmic NE face via a novel, vesicular intermediate. Although the molecular target was not identified, Ran is known to function by modulating protein interactions for karyopherin (Kap) β family members. Here we characterize loss-of-function Saccharomyces cerevisiae mutants in KAP95 with blocks in NPC assembly. Similar to defects in Ran cycle mutants, nuclear pore proteins are no longer localized properly to the NE in kap95 mutants. Also like Ran cycle mutants, the kap95-E126K mutant displayed enhanced lethality with nic96 and nup170 mutants. Thus, Kap95 and Ran are likely functioning at the same stage in assembly. However, although Ran cycle mutants accumulate small cytoplasmic vesicles, cells depleted of Kap95 accumulated long stretches of cytoplasmic membranes and had highly distorted NEs. We conclude that Kap95 serves as a key regulator of NPC assembly into intact NEs. Furthermore, both Kap95 and Ran may provide spatial cues necessary for targeting of vesicular intermediates in de novo NPC assembly.

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Two Nucleoporin 98 homologous genes jointly participate in the regulation of starch degradation to enhance growth in Arabidopsis

10.21203/rs.2.21484/v1 ◽

2020 ◽

Author(s):

Long Xiao ◽

Shanshan Jiang ◽

Penghui Huang ◽

Fulu Chen ◽

Xu Wang ◽

...

Keyword(s):

Energy Metabolism ◽

Nuclear Pore Complex ◽

Growth And Development ◽

Double Mutant ◽

Growth Regulation ◽

Starch Degradation ◽

Marker Genes ◽

Nuclear Pore ◽

Wild Type ◽

Senescence Phenotype

Abstract Background: Starch is synthesized during the day for temporary storage in leaves and then degraded during the subsequent night to support plant growth and development. Impairment of starch degradation leads to stunted growth, even senescence and death. The nuclear pore complex is involved in many cellular processes, but its relationship with starch degradation is unclear until now. We previously identified two Nucleoporin98 ( Nup98 ) genes ( Nup98a and Nup98b ) redundantly regulated flowering through CONSTANS ( CO ) independent pathway. in Arabidopsis thaliana. The nup98a nup98b double mutant also showed severe senescence phenotypes. Results: We found that Nucleoporin 98 ( Nup98 ) participated in the regulation of sugar metabolism in leaves and in turn is involved in senescence regulation in Arabidopsis . We show that Nup98a and Nup98b redundantly function in the different steps of starch degradation, the nup98a nup98b double mutant accumulates more starch than wild type and has a severe early senescence phenotype compared to wild type. The expression of marker genes related to starch degradation was impaired in the nup98a nup98b double mutant, and indicator genes of carbon starvation and senescence expressed earlier in the nup98a nup98b double mutant than that in wild type plants, suggesting abnormality of energy metabolism was the cause of senescence of the nup98a nup98b double mutant. Addition of sucrose to the growth medium can rescue early senescence phenotype of the nup98a nup98b mutant. Conclusions: Our results provided a line of evidence on a novel role of the nuclear pore complex in energy metabolism related to growth and development, whereas Nup98 functioned in starch degradation conferring growth regulation in Arabidopsis .

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A Novel Drosophila Minute Locus Encodes Ribosomal Protein S13

Genetics ◽

10.1093/genetics/143.2.877 ◽

1996 ◽

Vol 143 (2) ◽

pp. 877-885 ◽

Cited By ~ 1

Author(s):

Stein Saeboe-Larssen ◽

Andrew Lambertsson

Keyword(s):

Ribosomal Protein ◽

Ribosomal Proteins ◽

Transcript Level ◽

P Element ◽

Ribosomal Protein Genes ◽

Loss Of Function ◽

Wild Type ◽

Sequence Analyses ◽

Slow Development ◽

Ribosomal Protein S13

Abstract Minutes comprise >50 phenotypically similar Drosophila mutations believed to affect ribosomal protein genes. Common traits of the Minute phenotype are short and thin bristles, slow development, and recessive lethality. To further investigate the proposed Minute to ribosomal protein correspondence, loss-of-function Minute mutations were induced by P-element mutagenesis. Here, we report a previously undescribed Minute locus that maps to 32A on chromosome 2L; this Minute allele is named P{lac-W}M(2)32A1 and the gene M(2)32A. Flies heterozygous for P{lacW}M(2)32A1 have a medium Minute phenotype. The gene interrupted by the P-element insertion was cloned. Sequence analyses revealed that it encodes the Drosophila homologue of eukaryotic ribosomal protein S13. It is a singlecopy gene and the level of RPS13 transcript is reduced to ~50% in P{lacW}M(2)32A1 heterozygotes. Both transcript level and phenotype are restored to wild type by remobilizing the P element, demonstrating that the mutation is caused by insertion of the P-element construct. These results further strengthen the notion that Minutes encode ribosomal proteins and demonstrate that P-element mutagenesis is a fruitful approach to use in these studies.

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Sac3 Is an mRNA Export Factor That Localizes to Cytoplasmic Fibrils of Nuclear Pore Complex

Molecular Biology of the Cell ◽

10.1091/mbc.e02-08-0520 ◽

2003 ◽

Vol 14 (3) ◽

pp. 836-847 ◽

Cited By ~ 48

Author(s):

Elissa P. Lei ◽

Charlene A. Stern ◽

Birthe Fahrenkrog ◽

Heike Krebber ◽

Terence I. Moy ◽

...

Keyword(s):

Nuclear Pore Complex ◽

Nuclear Export ◽

Synthetic Lethality ◽

Mrna Export ◽

Nuclear Accumulation ◽

Nuclear Pore ◽

Messenger Rnas ◽

Loss Of Function ◽

Synthetic Lethal ◽

Starting Point

In eukaryotes, mRNAs are transcribed in the nucleus and exported to the cytoplasm for translation to occur. Messenger RNAs complexed with proteins referred to as ribonucleoparticles are recognized for nuclear export in part by association with Mex67, a keySaccharomyces cerevisiae mRNA export factor and homolog of human TAP/NXF1. Mex67, along with its cofactor Mtr2, is thought to promote ribonucleoparticle translocation by interacting directly with components of the nuclear pore complex (NPC). Herein, we show that the nuclear pore-associated protein Sac3 functions in mRNA export. Using a mutant allele of MTR2 as a starting point, we have identified a mutation in SAC3 in a screen for synthetic lethal interactors. Loss of function of SAC3 causes a strong nuclear accumulation of mRNA and synthetic lethality with a number of mRNA export mutants. Furthermore, Sac3 can be coimmunoprecipitated with Mex67, Mtr2, and other factors involved in mRNA export. Immunoelectron microscopy analysis shows that Sac3 localizes exclusively to cytoplasmic fibrils of the NPC. Finally, Mex67 accumulates at the nuclear rim when SAC3 is mutated, suggesting that Sac3 functions in Mex67 translocation through the NPC.

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In vivo nuclear transport kinetics in Saccharomyces cerevisiae: a role for heat shock protein 70 during targeting and translocation.

The Journal of Cell Biology ◽

10.1083/jcb.135.2.329 ◽

1996 ◽

Vol 135 (2) ◽

pp. 329-339 ◽

Cited By ~ 160

Author(s):

N Shulga ◽

P Roberts ◽

Z Gu ◽

L Spitz ◽

M M Tabb ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Heat Shock ◽

Heat Shock Protein ◽

Nuclear Pore Complex ◽

Heat Shock Protein 70 ◽

Nuclear Transport ◽

T Antigen ◽

Nuclear Pore ◽

Wild Type

The transport of proteins into the nucleus is a receptor-mediated process that is likely to involve between 50-100 gene products, including many that comprise the nuclear pore complex. We have developed an assay in Saccharomyces cerevisiae for the nuclear transport of green fluorescent protein fused to the SV-40 large T antigen nuclear localization signal (NLS-GFP). This assay allows the measurement of relative NLS-GFP nuclear import rates in wild-type and mutant cells under various physiological conditions. Probably the best understood component of the nuclear transport apparatus is Srp1p, the NLS receptor, which binds NLS-cargo in the cytoplasm and accompanies it into the nucleus. When compared to SRP1+ cells, NLS-GFP import rates in temperature-sensitive srp1-31 cells were slower and showed a lower temperature optimum. The in vivo transport defect of the srp1-31 cells was correlated with the purified protein's thermal sensitivity, as assayed by in vitro NLS peptide binding. We show that the kinetics of NLS-directed nuclear transport in wild-type cells is stimulated by the elevated expression of SSA1, which encodes a cytoplasmic heat shock protein 70 (Hsp70). Elevated Hsp70 levels are sufficient to suppress the NLS-GFP import defects in srp1-31 and nup82-3 cells. NUP82 encodes a protein that functions within the nuclear pore complex subsequent to docking. These results provide genetic evidence that Hsp70 acts during both targeting and translocation phases of nuclear transport, possibly as a molecular chaperone to promote the formation and stability of the Srp1p-NLS-cargo complex.

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