scholarly journals Fragile X–Related Protein 1 Regulates Nucleoporin Localization in a Cell Cycle–Dependent Manner

2021 ◽  
Vol 9 ◽  
Author(s):  
Arantxa Agote-Arán ◽  
Junyan Lin ◽  
Izabela Sumara
Keyword(s):  
Cell Cycle ◽  
Mammalian Cells ◽  
Cell Cycle Progression ◽  
Fragile X ◽  
Protein Translation ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Dependent Manner ◽  
Independent Manner ◽  
Cycle Dependent

Nuclear pore complexes (NPCs) are embedded in the nuclear envelope (NE) where they ensure the transport of macromolecules between the nucleus and the cytoplasm. NPCs are built from nucleoporins (Nups) through a sequential assembly order taking place at two different stages during the cell cycle of mammalian cells: at the end of mitosis and during interphase. In addition, fragile X–related proteins (FXRPs) can interact with several cytoplasmic Nups and facilitate their localization to the NE during interphase likely through a microtubule-dependent mechanism. In the absence of FXRPs or microtubule-based transport, Nups aberrantly localize to the cytoplasm forming the so-called cytoplasmic nucleoporin granules (CNGs), compromising NPCs’ function on protein export. However, it remains unknown if Nup synthesis or degradation mechanisms are linked to the FXRP–Nup pathway and if and how the action of FXRPs on Nups is coordinated with the cell cycle progression. Here, we show that Nup localization defects observed in the absence of FXR1 are independent of active protein translation. CNGs are cleared in an autophagy- and proteasome-independent manner, and their presence is restricted to the early G1 phase of the cell cycle. Our results thus suggest that a pool of cytoplasmic Nups exists that contributes to the NPC assembly specifically during early G1 to ensure NPC homeostasis at a short transition from mitosis to the onset of interphase.

scholarly journals Spatial control of nucleoporin assembly by Fragile X-related proteins

2019 ◽  
Author(s):  
Arantxa Agote-Arán ◽  
Stephane Schmucker ◽  
Katerina Jerabkova ◽  
Inès Jmel Boyer ◽  
Alessandro Berto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
Fragile X Syndrome ◽  
Cell Cycle Progression ◽  
Fragile X ◽  
Nuclear Pore ◽  
Nuclear Morphology ◽  
Nuclear Pore Complexes ◽  
Cycle Progression ◽  
Pore Complexes

SummaryNucleoporins (Nups) build highly organized Nuclear Pore Complexes (NPCs) at the nuclear envelope (NE). Several Nups assemble into a sieve-like hydrogel within the central channel of the NPCs to regulate nucleocytoplasmic exchange. In the cytoplasm, a large excess of soluble Nups has been reported, but how their assembly is restricted to the NE is currently unknown. Here we show that Fragile X-related protein 1 (FXR1) can interact with several Nups and facilitate their localization to the NE during interphase through a microtubule and dynein-dependent mechanism. Downregulation of FXR1 or closely related orthologs FXR2 and Fragile X mental retardation protein (FMRP) leads to the accumulation of cytoplasmic Nup protein condensates. Likewise, several models of Fragile X syndrome (FXS), characterized by a loss of FMRP, also accumulate cytoplasmic Nup aggregates. These aggregate-containing cells display aberrant nuclear morphology and a delay in G1 cell cycle progression. Our results reveal an unexpected role for the FXR protein family and dynein in the spatial regulation of nucleoporin assembly.HighlightsCytoplasmic nucleoporins are assembled by Fragile X-related (FXR) proteins and dyneinFXR-Dynein pathway downregulation induces aberrant cytoplasmic aggregation of nucleoporinsCellular models of Fragile X syndrome accumulate aberrant cytoplasmic nucleoporin aggregates.FXR-Dynein pathway regulates nuclear morphology and G1 cell cycle progressioneTOC BlurbNucleoporins (Nups) form Nuclear Pore Complexes (NPCs) at the nuclear envelope. Agote-Arán at al. show how cells inhibit aberrant assembly of Nups in the cytoplasm and identify Fragile X-related (FXR) proteins and dynein that facilitate localization of Nups to the nuclear envelope and control G1 cell cycle progression.Graphical abstract

scholarly journals Dynamic Alterations of Histone H3 Phospho-acetylation Correlate With Radio Sensitivity of Mitotic Cells During DNA Damage

2020 ◽  
Author(s):  
Asmita Sharda ◽  
Tripti Verma ◽  
Nikhil Gadewal ◽  
Sanjay Gupta
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Dna Repair ◽  
Cell Cycle Progression ◽  
Protein Translation ◽  
Chemotherapeutic Agents ◽  
Open Chromatin ◽  
Dependent Manner ◽  
A Cell ◽  
Cycle Dependent

Abstract Background - Histone Post Translational Modifications (PTMs) change in a cell cycle dependent manner and also orchestrate the DNA repair process for radiation induced DNA damage. Mitosis is the most radiosensitive phase of the cell cycle but the epigenetic events that regulate its radiosensitivity remain elusive.Results - This study explored the dynamics between histone marks H3S10/S28ph, H3K9ac and γH2AX during mitotic DNA damage response. The presence of a mononucleosome level association between γH2AX and H3S10ph was observed only during mitosis. This association was abrogated upon cell cycle progression and chromatin de-condensation, concomitant with chromatin recruitment of DNA repair proteins Ku70 and Rad51. Moreover, the levels of H3S10/28ph remained unchanged upon DNA damage during mitosis, but decreased in a cell cycle dependent manner upon mitotic exit. However, the population that arose after mitotic progression of damaged cells comprised of binucleated tetraploid cells. This population was epigenetically distinct from interphase cells, characterized by reduced H3S10/S28ph, increased H3K9ac and more open chromatin configuration. These epigenetic features correlated with decreased survival potential of this population. The low levels of H3S10/28ph were attributed to decreased protein translation and chromatin recruitment of histone kinase Mitogen and Stress-activated Kinase 1 (MSK1) along with persistent levels of Protein phosphatase1 catalytic subunit α (PP1α). Conclusions – This study suggests that a unique epigenetic landscape attained during and after mitotic DNA damage collectively contributed to mitotic radiosensitivity. The findings of this study have potential clinical significance in terms of tackling resistance against anti-mitotic chemotherapeutic agents.

Cell cycle dependent localization of the telomeric PARP, tankyrase, to nuclear pore complexes and centrosomes

1999 ◽  
Vol 112 (21) ◽  
pp. 3649-3656 ◽  
Author(s):  
S. Smith ◽  
T. de Lange
Keyword(s):  
Cell Cycle ◽  
Subcellular Fractionation ◽  
Negative Regulator ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Dependent Manner ◽  
Telomeric Dna ◽  
Cycle Dependent ◽  
Pore Complexes

Tankyrase is a human poly(ADP-ribose) polymerase that was initially identified through its interaction with the telomeric protein TRF1, a negative regulator of telomere length. In vitro poly(ADP-ribosyl)ation by tankyrase inhibits TRF1 binding to telomeric DNA suggesting a role for tankyrase in telomere function. We previously demonstrated that tankyrase co-localizes with TRF1 at the ends of human chromosomes in metaphase. Here we show that tankyrase localizes to additional subcellular sites in a cell cycle dependent manner. In interphase, tankyrase co-localized with TRF1 to telomeres, but in addition was found to reside at nuclear pore complexes, as evidenced by indirect immunofluorescence, subcellular fractionation and immunoelectron microscopy. At mitosis, concomitant with nuclear envelope breakdown and nuclear pore complex disassembly, tankyrase was found to relocate around the pericentriolar matrix of mitotic centrosomes. This complex staining pattern along with the observation that tankyrase did not contain a nuclear localization signal suggested that its telomeric localization might be regulated, perhaps by TRF1. Indeed, localization of exogenously-expressed tankyrase to telomeres was dependent upon co-transfection with TRF1. These data indicate that the subcellular localization of tankyrase can be regulated by both the cell cycle and TRF1.

scholarly journals E2F activity is regulated by cell cycle-dependent changes in subcellular localization.

1997 ◽  
Vol 17 (12) ◽  
pp. 7268-7282 ◽  
Author(s):  
R Verona ◽  
K Moberg ◽  
S Estes ◽  
M Starz ◽  
J P Vernon ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Subcellular Localization ◽  
Nuclear Localization ◽  
Mammalian Cells ◽  
Critical Role ◽  
Biological Properties ◽  
Dependent Manner ◽  
Restriction Point ◽  
Cycle Dependent ◽  
Almost All

E2F directs the cell cycle-dependent expression of genes that induce or regulate the cell division process. In mammalian cells, this transcriptional activity arises from the combined properties of multiple E2F-DP heterodimers. In this study, we show that the transcriptional potential of individual E2F species is dependent upon their nuclear localization. This is a constitutive property of E2F-1, -2, and -3, whereas the nuclear localization of E2F-4 is dependent upon its association with other nuclear factors. We previously showed that E2F-4 accounts for the majority of endogenous E2F species. We now show that the subcellular localization of E2F-4 is regulated in a cell cycle-dependent manner that results in the differential compartmentalization of the various E2F complexes. Consequently, in cycling cells, the majority of the p107-E2F, p130-E2F, and free E2F complexes remain in the cytoplasm. In contrast, almost all of the nuclear E2F activity is generated by pRB-E2F. This complex is present at high levels during G1 but disappears once the cells have passed the restriction point. Surprisingly, dissociation of this complex causes little increase in the levels of nuclear free E2F activity. This observation suggests that the repressive properties of the pRB-E2F complex play a critical role in establishing the temporal regulation of E2F-responsive genes. How the differential subcellular localization of pRB, p107, and p130 contributes to their different biological properties is also discussed.

scholarly journals Coupling Phosphate Homeostasis to Cell Cycle-Specific Transcription: Mitotic Activation of Saccharomyces cerevisiae PHO5 by Mcm1 and Forkhead Proteins

2009 ◽  
Vol 29 (18) ◽  
pp. 4891-4905 ◽  
Author(s):  
Santhi Pondugula ◽  
Daniel W. Neef ◽  
Warren P. Voth ◽  
Russell P. Darst ◽  
Archana Dhasarathy ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Mitotic Cell ◽  
Dependent Manner ◽  
Phosphate Homeostasis ◽  
Periodic Cell ◽  
M Phase ◽  
Cycle Dependent ◽  
Nutrient Homeostasis

ABSTRACT Cells devote considerable resources to nutrient homeostasis, involving nutrient surveillance, acquisition, and storage at physiologically relevant concentrations. Many Saccharomyces cerevisiae transcripts coding for proteins with nutrient uptake functions exhibit peak periodic accumulation during M phase, indicating that an important aspect of nutrient homeostasis involves transcriptional regulation. Inorganic phosphate is a central macronutrient that we have previously shown oscillates inversely with mitotic activation of PHO5. The mechanism of this periodic cell cycle expression remains unknown. To date, only two sequence-specific activators, Pho4 and Pho2, were known to induce PHO5 transcription. We provide here evidence that Mcm1, a MADS-box protein, is essential for PHO5 mitotic activation. In addition, we found that cells simultaneously lacking the forkhead proteins, Fkh1 and Fkh2, exhibited a 2.5-fold decrease in PHO5 expression. The Mcm1-Fkh2 complex, first shown to transactivate genes within the CLB2 cluster that drive G2/M progression, also associated directly at the PHO5 promoter in a cell cycle-dependent manner in chromatin immunoprecipitation assays. Sds3, a component specific to the Rpd3L histone deacetylase complex, was also recruited to PHO5 in G1. These findings provide (i) further mechanistic insight into PHO5 mitotic activation, (ii) demonstrate that Mcm1-Fkh2 can function combinatorially with other activators to yield late M/G1 induction, and (iii) couple the mitotic cell cycle progression machinery to cellular phosphate homeostasis.

Two proteins that cycle asynchronously between centrosomes and nuclear structures: Drosophila CP60 and CP190

1997 ◽  
Vol 110 (14) ◽  
pp. 1573-1583 ◽  
Author(s):  
K. Oegema ◽  
W.F. Marshall ◽  
J.W. Sedat ◽  
B.M. Alberts
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
Wide Field ◽  
Dependent Manner ◽  
Independent Manner ◽  
Nuclear Envelope Breakdown ◽  
Nuclear Structures ◽  
Dynamic Structures ◽  
Cycle Dependent

Both the nucleus and the centrosome are complex, dynamic structures whose architectures undergo cell cycle-specific rearrangements. CP190 and CP60 are two Drosophila proteins of unknown function that shuttle between centrosomes and nuclei in a cell cycle-dependent manner. These two proteins are associated in vitro, and localize to centrosomes in a microtubule independent manner. We injected fluorescently labeled, bacterially expressed CP190 and CP60 into living Drosophila embryos and followed their behavior during the rapid syncytial blastoderm divisions (nuclear cycles 10–13). Using quantitative 3-D wide-field fluorescence microscopy, we show that CP190 and CP60 cycle between nuclei and centrosomes asynchronously with the accumulation of CP190 leading that of CP60 both at centrosomes and in nuclei. During interphase, CP190 is found in nuclei. Immediately following nuclear envelope breakdown, CP190 localizes to centrosomes where it remains until telophase, thereafter accumulating in reforming nuclei. Unlike CP190, CP60 accumulates at centrosomes primarily during anaphase, where it remains into early interphase. During nuclear cycles 10 and 11, CP60 accumulates in nuclei simultaneous with nuclear envelope breakdown, suggesting that CP60 binds to an unknown nuclear structure that persists into mitosis. During nuclear cycles 12 and 13, CP60 accumulates gradually in nuclei during interphase, reaching peak levels just before nuclear envelope breakdown. Once in the nucleus, both CP190 and CP60 appear to form fibrous intranuclear networks that remain coherent even after nuclear envelope breakdown. The CP190 and CP60 networks do not co-localize extensively with each other or with DNA. This work provides direct evidence, in living cells, of a coherent protein network that may represent a nuclear skeleton.

C-terminal domain phosphorylation of ERK3 controlled by Cdk1 and Cdc14 regulates its stability in mitosis

2010 ◽  
Vol 428 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Pierre-Luc Tanguay ◽  
Geneviève Rodier ◽  
Sylvain Meloche
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Mitotic Cell ◽  
Mitogen Activated Protein Kinase ◽  
Phosphorylation Sites ◽  
Dependent Manner ◽  
Cell Extracts ◽  
Cycle Dependent

ERK3 (extracellular-signal-regulated kinase 3) is an atypical MAPK (mitogen-activated protein kinase) that is suggested to play a role in cell-cycle progression and cellular differentiation. However, it is not known whether the function of ERK3 is regulated during the cell cycle. In the present paper, we report that ERK3 is stoichiometrically hyperphosphorylated during entry into mitosis and is dephosphorylated at the M→G1 transition. The phosphorylation of ERK3 is associated with the accumulation of the protein in mitosis. In vitro phosphorylation of a series of ERK3-deletion mutants by mitotic cell extracts revealed that phosphorylation is confined to the unique C-terminal extension of the protein. Using MS analysis, we identified four novel phosphorylation sites, Ser684, Ser688, Thr698 and Ser705, located at the extreme C-terminus of ERK3. All four sites are followed by a proline residue. We have shown that purified cyclin B-Cdk1 (cyclindependent kinase 1) phosphorylates these sites in vitro and demonstrate that Cdk1 acts as a major Thr698 kinase in vivo. Reciprocally, we found that the phosphatases Cdc14A and Cdc14B (Cdc is cell-division cycle) bind to ERK3 and reverse its C-terminal phosphorylation in mitosis. Importantly, alanine substitution of the four C-terminal phosphorylation sites markedly decreased the half-life of ERK3 in mitosis, thereby linking phosphorylation to the stabilization of the kinase. The results of the present study identify a novel regulatory mechanism of ERK3 that operates in a cell-cycle-dependent manner.

scholarly journals Histone H1 of Trypanosoma cruzi Is Concentrated in the Nucleolus Region and Disperses upon Phosphorylation during Progression to Mitosis

2008 ◽  
Vol 7 (4) ◽  
pp. 560-568 ◽  
Author(s):  
Luciana M. Gutiyama ◽  
Julia P. Chagas da Cunha ◽  
Sergio Schenkman
Keyword(s):  
Cell Cycle ◽  
Trypanosoma Cruzi ◽  
Cell Cycle Progression ◽  
Histone H1 ◽  
Nuclear Space ◽  
Dependent Manner ◽  
Central Regions ◽  
Core Histones ◽  
A Cell ◽  
Cycle Dependent

ABSTRACT Phosphorylation of histone H1 is intimately related to the cell cycle progression in higher eukaryotes, reaching maximum levels during mitosis. We have previously shown that in the flagellated protozoan Trypanosoma cruzi, which does not condense chromatin during mitosis, histone H1 is phosphorylated at a single cyclin-dependent kinase site. By using an antibody that recognizes specifically the phosphorylated T. cruzi histone H1 site, we have now confirmed that T. cruzi histone H1 is also phosphorylated in a cell cycle-dependent manner. Differently from core histones, the bulk of nonphosphorylated histone H1 in G1 and S phases of the cell cycle is concentrated in the central regions of the nucleus, which contains the nucleolus and less densely packed chromatin. When cells pass G2, histone H1 becomes phosphorylated and starts to diffuse. At the onset of mitosis, histone H1 phosphorylation is maximal and found in the entire nuclear space. As permeabilized parasites preferentially lose phosphorylated histone H1, we conclude that this modification promotes its release from less condensed and nucleolar chromatin after G2.

scholarly journals Morphogenesis checkpoint kinase Swe1 is the executor of lipolysis-dependent cell-cycle progression

2015 ◽  
Vol 112 (10) ◽  
pp. E1077-E1085 ◽  
Author(s):  
Neha Chauhan ◽  
Myriam Visram ◽  
Alvaro Cristobal-Sarramian ◽  
Florian Sarkleti ◽  
Sepp D. Kohlwein
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Sphingolipid Metabolism ◽  
Dependent Manner ◽  
Cycle Progression ◽  
Checkpoint Kinase ◽  
Cell Cycle Delay ◽  
A Cell ◽  
Morphogenesis Checkpoint ◽  
Cycle Dependent

Cell growth and division requires the precise duplication of cellular DNA content but also of membranes and organelles. Knowledge about the cell-cycle–dependent regulation of membrane and storage lipid homeostasis is only rudimentary. Previous work from our laboratory has shown that the breakdown of triacylglycerols (TGs) is regulated in a cell-cycle–dependent manner, by activation of the Tgl4 lipase by the major cyclin-dependent kinase Cdc28. The lipases Tgl3 and Tgl4 are required for efficient cell-cycle progression during the G1/S (Gap1/replication phase) transition, at the onset of bud formation, and their absence leads to a cell-cycle delay. We now show that defective lipolysis activates the Swe1 morphogenesis checkpoint kinase that halts cell-cycle progression by phosphorylation of Cdc28 at tyrosine residue 19. Saturated long-chain fatty acids and phytosphingosine supplementation rescue the cell-cycle delay in the Tgl3/Tgl4 lipase-deficient strain, suggesting that Swe1 activity responds to imbalanced sphingolipid metabolism, in the absence of TG degradation. We propose a model by which TG-derived sphingolipids are required to activate the protein phosphatase 2A (PP2ACdc55) to attenuate Swe1 phosphorylation and its inhibitory effect on Cdc28 at the G1/S transition of the cell cycle.

scholarly journals The microtubule plus-end tracking protein Bik1 is required for chromosome congression

2021 ◽  
Author(s):  
Alexander Julner ◽  
Marjan Abbasi ◽  
Victoria Menendez Benito
Keyword(s):  
Cell Cycle ◽  
Nuclear Export ◽  
Cell Cycle Progression ◽  
Nuclear Export Signal ◽  
Microtubule Dynamics ◽  
Dependent Manner ◽  
Chromosome Congression ◽  
A Cell ◽  
Cycle Dependent ◽  
Export Signal

During mitosis, sister chromatids congress on either side of the spindle equator to facilitate the correct partitioning of the genomic material. Chromosome congression requires a finely tuned control of microtubule dynamics by the kinesin motor proteins. In Saccharomyces cerevisiae, the kinesin proteins Cin8, Kip1, and Kip3 have pivotal roles in chromosome congression. It has been hypothesized that additional proteins that modulate microtubule dynamics are also involved. Here, we show that the microtubule plus-end tracking protein Bik1 (the budding yeast ortholog of CLIP-170) is essential for chromosome congression. We find that nuclear Bik1 localizes to the kinetochores in a cell-cycle-dependent manner. Disrupting the nuclear pool of Bik1 with a nuclear export signal (Bik1-NES) leads to a slower cell cycle progression characterized by a delayed metaphase-anaphase transition. Bik1-NES cells have mispositioned kinetochores along the spindle in metaphase. Furthermore, using proximity-dependent methods, we identify Cin8 as an interaction partner of Bik1. Deleting CIN8 reduces the amount of Bik1 at the spindle. In contrast, Cin8 retains its typical bilobed distribution in Bik1-NES and does not localize to the unclustered kinetochores characteristic of Bik1-NES cells. Thus, we propose that Bik1 functions together with Cin8 to regulate kinetochore-microtubule dynamics for correct kinetochore positioning and chromosome congression.

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