scholarly journals UVB-Induced Nuclear Translocation of PTEN Promotes Radiation Sensitivity of Human Malignant Glioma U87MG Cells

2020 ◽  
Author(s):  
Wei Zhao ◽  
Chao Yao ◽  
Yang An ◽  
Yuting Jia ◽  
Zhenhua Song ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Uv Irradiation ◽  
Nuclear Translocation ◽  
Radiation Sensitivity ◽  
Suppressor Gene ◽  
Nuclear Accumulation ◽  
Dependent Manner ◽  
Phosphatidylinositol 3 Kinase ◽  
Pi3k Signaling Pathway ◽  
The Relationship

Abstract BackgroundPTEN is a tumor suppressor gene, which is often inactivated through mutation and/or deletion in diverse human tumors. In the cytoplasm, PTEN negatively regulates the phosphatidylinositol 3′ kinase (PI3K) signaling pathway, while PTEN also shuttles to the nucleus, where PTEN stabilizes genome and/or participates in DNA repairment after damage. PTEN’s subcellular localization seems to be regulated by various factors. MethodsU87MG cells with expressing Wild-type-PTEN (WT-PTEN) and K13E-PTEN mutant were engineered respectively. The relationship between UV radiation and PTEN’s subcellular localization were elucidated using nuclear and cytosolic fractionation and fluorescence co-localization assay. Related signaling pathways were studied with western blot assays.ResultsHere, we demonstrated that UV irradiation could promote nuclear translocation of both WT-PTEN and K13E-PTEN mutant in a dose-dependent manner, but WT PTEN had a higher level of nuclear accumulation after inducing by UV-irradiation compared to K13E-PTEN. In contrast, the cytoplasmic-nuclear translocation of exogenous PTEN was critical to its tumor-suppressing functions that made U87MG cells more sensitive to the UV irradiation. ConclusionOur findings may have implications for further revealing the function of nuclear PTEN and provide insights for clinical treatment of PTEN-deficient tumors.

scholarly journals DNase II mediates a parthanatos-like developmental cell death pathway in Drosophila primordial germ cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lama Tarayrah-Ibraheim ◽  
Elital Chass Maurice ◽  
Guy Hadary ◽  
Sharon Ben-Hur ◽  
Alina Kolpakova ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Germ Cells ◽  
Nuclear Translocation ◽  
Primordial Germ Cells ◽  
Nuclear Accumulation ◽  
Dependent Manner ◽  
Dnase Ii ◽  
Cell Death Pathway ◽  
Parp 1

AbstractDuring Drosophila embryonic development, cell death eliminates 30% of the primordial germ cells (PGCs). Inhibiting apoptosis does not prevent PGC death, suggesting a divergence from the conventional apoptotic program. Here, we demonstrate that PGCs normally activate an intrinsic alternative cell death (ACD) pathway mediated by DNase II release from lysosomes, leading to nuclear translocation and subsequent DNA double-strand breaks (DSBs). DSBs activate the DNA damage-sensing enzyme, Poly(ADP-ribose) (PAR) polymerase-1 (PARP-1) and the ATR/Chk1 branch of the DNA damage response. PARP-1 and DNase II engage in a positive feedback amplification loop mediated by the release of PAR polymers from the nucleus and the nuclear accumulation of DNase II in an AIF- and CypA-dependent manner, ultimately resulting in PGC death. Given the anatomical and molecular similarities with an ACD pathway called parthanatos, these findings reveal a parthanatos-like cell death pathway active during Drosophila development.

scholarly journals Hypercholesterolaemic Serum Increases the Permeability of Endothelial Cells through Zonula Occludens-1 with Phosphatidylinositol 3-Kinase Signaling Pathway

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Chang Bian ◽  
Geng Xu ◽  
Jianan Wang ◽  
Ji Ma ◽  
MeiXiang Xiang ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Signaling Pathway ◽  
Pi3k Signaling ◽  
Dependent Manner ◽  
Phosphatidylinositol 3 Kinase ◽  
Zonula Occludens ◽  
Cultured Endothelial Cells ◽  
Pi3k Signaling Pathway ◽  
Zonula Occludens 1 ◽  
Phosphatidylinositol 3

Purpose. Hypercholesterolemia and tight junctions play important roles in atherosclerosis. But the relationship between these two factors is unclear. In the present study, we investigated whether hypercholesterolemic serum could change the permeability of endothelial cells through altering expression and/or distribution of tight junction protein zonula occludens-1 (ZO-1). Phosphatidylinositol 3-kinase (PI3K) signaling pathway was also examined.Materials and Methods. Cultured endothelial cells were treated with different concentration levels of hypercholesterolemic serum. The expression and distribution of ZO-1, the permeability of cultured cells and the involvement of PI3K signaling pathway were measured by various methods.Results. In the present study, we found that hypercholesterolemic serum could not change the expression of ZO-1 either in mRNA or protein level. However, hypercholesterolemic serum could change the distribution of ZO-1 in cultured endothelial cells, and increase the permeability with a dose-dependent manner. When PI3K specific inhibitor wortmannin was used, the effects induced by hypercholesterolemic serum could be partly reversed. The role of PI3K signaling pathway was further confirmed by PI3K activity assay.Conclusions. Our results suggested that although hypercholesterolemic serum could not change the expression of ZO-1, it could change the distribution and increase the permeability in endothelial cells through PI3K signaling pathway.

scholarly journals Identification of a putative nuclear localization signal in maspin protein shed light into its nuclear import regulation

2018 ◽  
Author(s):  
Jeffrey Reina ◽  
Lixin Zhou ◽  
Marcos R.M. Fontes ◽  
Nelly Panté ◽  
Nathalie Cella
Keyword(s):  
Subcellular Localization ◽  
Nuclear Localization ◽  
Hela Cells ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Biological Activities ◽  
Dependent Manner ◽  
Localization Signal

AbstractMaspin (SERPINB5) is a potential tumor suppressor gene with pleiotropic biological activities, including regulation of cell proliferation, death, adhesion, migration and gene expression. Several studies suggest that subcellular localization plays an essential role on maspin tumor suppression activity. In this study we investigated the molecular mechanisms underlying maspin nucleocytoplasmic shuttling. Anin vitronuclear-import assay using digitonin-permeabilized HeLa cells demonstrated that maspin enters the nucleus by an energy-and carrier-independent mechanism. However, previous studies indicated that maspin subcellular localization is regulated in the cell. Using a nuclear localization signal (NLS) prediction software, we identified a putative NLS in the maspin amino acid sequence. To distinguish between passive and regulated nuclear translocation, maspinNLS or the full-length protein (MaspinFL) were fused to 5GFP, rendering the construct too large to enter the nucleus passively. Unexpectedly, 5GFP-maspinNLS, but not maspinFL-5GFP, entered the nucleus of HeLa cells. Dominant-negative Ran-GTPase mutants RanQ69L or RanT24N, suppressed 5GFP-maspinNLS nuclear localization. In summary, we provide evidence that maspin translocates to the nucleus passively. In addition, we identified a peptide in the maspin protein sequence, which is able to drive a 5GFP construct to the nucleus in an energy-dependent manner.

scholarly journals The Novel Phosphatidylinositol-3-Kinase (PI3K) Inhibitor Alpelisib Effectively Inhibits Growth of PTEN-Haploinsufficient Lipoma Cells

Cancers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1586 ◽  
Author(s):  
Anna S. Kirstein ◽  
Adrien Augustin ◽  
Melanie Penke ◽  
Michele Cea ◽  
Antje Körner ◽  
...  
Keyword(s):  
Cell Death ◽  
Adipocyte Differentiation ◽  
Suppressor Gene ◽  
Pi3k Inhibitor ◽  
Dependent Manner ◽  
The Novel ◽  
Phosphatidylinositol 3 Kinase ◽  
Akt Phosphorylation ◽  
Ribosomal Protein S6 ◽  
New Treatment

Germline mutations in the tumor suppressor gene PTEN cause PTEN Hamartoma Tumor Syndrome (PHTS). Pediatric patients with PHTS frequently develop lipomas. Treatment attempts with the mTORC1 inhibitor rapamycin were unable to reverse lipoma growth. Recently, lipomas associated with PIK3CA-related overgrowth syndrome were successfully treated with the novel PI3K inhibitor alpelisib. Here, we tested whether alpelisib has growth-restrictive effects and induces cell death in lipoma cells. We used PTEN-haploinsufficient lipoma cells from three patients and treated them with alpelisib alone or in combination with rapamycin. We tested the effect of alpelisib on viability, proliferation, cell death, induction of senescence, adipocyte differentiation, and signaling at 1–100 µM alpelisib. Alpelisib alone or in combination with rapamycin reduced proliferation in a concentration- and time-dependent manner. No cell death but an induction of senescence was detected after alpelisib incubation for 72 h. Alpelisib treatment led to a reduced phosphorylation of AKT, mTOR, and ribosomal protein S6. Rapamycin treatment alone led to increased AKT phosphorylation. This effect could be reversed by combining rapamycin with alpelisib. Alpelisib reduced the size of lipoma spheroids by attenuating adipocyte differentiation. Since alpelisib was well tolerated in first clinical trials, this drug alone or in combination with rapamycin is a potential new treatment option for PHTS-related adipose tissue overgrowth.

scholarly journals Regulation of RelA Subcellular Localization by a Putative Nuclear Export Signal and p50

1999 ◽  
Vol 19 (10) ◽  
pp. 7088-7095 ◽  
Author(s):  
Edward W. Harhaj ◽  
Shao-Cong Sun
Keyword(s):  
Subcellular Localization ◽  
Nuclear Export ◽  
Nuclear Translocation ◽  
Nuclear Export Signal ◽  
Nuclear Factor Κb ◽  
Nuclear Accumulation ◽  
Physical Interaction ◽  
Cytoplasmic Localization ◽  
Heterologous Proteins ◽  
Export Signal

ABSTRACT Nuclear factor κB (NF-κB) represents a family of dimeric DNA binding proteins, the pleotropic form of which is a heterodimer composed of RelA and p50 subunits. The biological activity of NF-κB is controlled through its subcellular localization. Inactive NF-κB is sequestered in the cytoplasm by physical interaction with an inhibitor, IκBα. Signal-mediated IκBα degradation triggers the release and subsequent nuclear translocation of NF-κB. It remains unknown whether the NF-κB shuttling between the cytoplasm and nucleus is subjected to additional steps of regulation. In this study, we demonstrated that the RelA subunit of NF-κB exhibits strong cytoplasmic localization activity even in the absence of IκBα inhibition. The cytoplasmic distribution of RelA is largely mediated by a leucine-rich sequence homologous to the recently characterized nuclear export signal (NES). This putative NES is both required and sufficient to mediate cytoplasmic localization of RelA as well as that of heterologous proteins. Furthermore, the cytoplasmic distribution of RelA is sensitive to a nuclear export inhibitor, leptomycin B, suggesting that RelA undergoes continuous nuclear export. Interestingly, expression of p50 prevents the cytoplasmic expression of RelA, leading to the nuclear accumulation of both RelA and p50. Together, these results suggest that the nuclear and cytoplasmic shuttling of RelA is regulated by both an intrinsic NES-like sequence and the p50 subunit of NF-κB.

scholarly journals PI3K-AKT, JAK2-STAT3 pathways and cell–cell contact regulate maspin subcellular localization

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
M. T. Longhi ◽  
L. E. Silva ◽  
M. Pereira ◽  
M. Magalhães ◽  
J. Reina ◽  
...  
Keyword(s):  
Subcellular Localization ◽  
Nuclear Localization ◽  
Biological Activities ◽  
Suppressor Gene ◽  
Nuclear Accumulation ◽  
Translation Regulation ◽  
Cell Contact ◽  
Downstream Signaling ◽  
Cell Cell

Abstract Background Maspin (SERPINB5) is a potential tumor suppressor gene with pleiotropic biological activities, including regulation of cell proliferation, death, adhesion, migration and gene expression. Several studies indicate that nuclear localization is essential for maspin tumor suppression activity. We have previously shown that the EGFR activation leads to maspin nuclear localization in MCF-10A cells. The present study investigated which EGFR downstream signaling molecules are involved in maspin nuclear localization and explored a possible role of cell–cell contact in this process. Methods MCF-10A cells were treated with pharmacological inhibitors against EGFR downstream pathways followed by EGF treatment. Maspin subcellular localization was determined by immunofluorescence. Proteomic and interactome analyses were conducted to identify maspin-binding proteins in EGF-treated cells only. To investigate the role of cell–cell contact these cells were either treated with chelating agents or plated on different cell densities. Maspin and E-cadherin subcellular localization was determined by immunofluorescence. Results We found that PI3K-Akt and JAK2-STAT3, but not MAP kinase pathway, regulate EGF-induced maspin nuclear accumulation in MCF-10A cells. We observed that maspin is predominantly nuclear in sparse cell culture, but it is redistributed to the cytoplasm in confluent cells even in the presence of EGF. Proteomic and interactome results suggest a role of maspin on post-transcriptional and translation regulation, protein folding and cell–cell adhesion. Conclusions Maspin nuclear accumulation is determined by an interplay between EGFR (via PI3K-Akt and JAK2-STAT3 pathways) and cell–cell contact.

scholarly journals Nuclear-Cytoplasmic Shuttling of Menin Regulates Nuclear Translocation of β-Catenin

2009 ◽  
Vol 29 (20) ◽  
pp. 5477-5487 ◽  
Author(s):  
Yanan Cao ◽  
Ruixin Liu ◽  
Xiuli Jiang ◽  
Jieli Lu ◽  
Jingjing Jiang ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Nuclear Translocation ◽  
Control Cell ◽  
Abnormal Development ◽  
Nuclear Accumulation ◽  
Null Mouse ◽  
Dependent Manner ◽  
Embryonic Fibroblasts ◽  
Proliferation And Apoptosis

ABSTRACT Menin, which is encoded by the multiple endocrine neoplasia type 1 (MEN1) gene, is a tumor suppressor and transcriptional regulator. Menin controls proliferation and apoptosis of cells, especially pancreatic β cells. We have found that menin contains two functional nuclear export signals and that there is nuclear accumulation of β-catenin in Men1-null mouse embryonic fibroblasts and insulinoma tissues from β-cell-specific Men1 knockout mice. It is reported that the deregulation of Wnt/β-catenin signaling caused by inactivation of tumor suppressors results in abnormal development or tumorigenesis. We further revealed that overexpression of menin reduces β-catenin nuclear accumulation and its transcriptional activity. Menin is able to directly interact with β-catenin and carry β-catenin out of the nucleus via nuclear-cytoplasmic shuttling in a CRM1-dependent manner. These results imply that menin may control cell proliferation through suppression of Wnt/β-catenin signaling.

scholarly journals Akt Down-Regulates ERK1/2 Nuclear Localization and Angiotensin II-induced Cell Proliferation through PEA-15

2006 ◽  
Vol 17 (9) ◽  
pp. 3940-3951 ◽  
Author(s):  
Marianne Gervais ◽  
Céline Dugourd ◽  
Laurent Muller ◽  
Corinne Ardidie ◽  
Brigitte Canton ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Cross Talk ◽  
Nuclear Translocation ◽  
Chinese Hamster ◽  
Nuclear Accumulation ◽  
Phosphatidylinositol 3 Kinase ◽  
Akt Activation ◽  
Extracellular Signal ◽  
Regulate Cell Growth ◽  
Functional Consequences

Angiotensin II (AngII) type 1 receptors (AT1) regulate cell growth through the extracellular signal-regulated kinase (ERK)1/2 and phosphatidylinositol 3-kinase (PI3K) pathways. ERK1/2 and Akt/protein kinase B, downstream of PI3K, are independently activated but both required for mediating AngII-induced proliferation when expressed at endogenous levels. We investigate the effect of an increase in the expression of wild-type Akt1 by using Chinese hamster ovary (CHO)-AT1 cells. Unexpectedly, Akt overexpression inhibits the AT1-mediated proliferation. This effect could be generated by a cross-talk between the PI3K and ERK1/2 pathways. A functional partner is the phosphoprotein enriched in astrocytes of 15 kDa (PEA-15), an Akt substrate known to bind ERK1/2 and to regulate their nuclear translocation. We report that Akt binds to PEA-15 and that Akt activation leads to PEA-15 stabilization, independently of PEA-15 interaction with ERK1/2. Akt cross-talk with PEA-15 does not affect ERK1/2 activation but decreases their nuclear activity as a result of the blockade of ERK1/2 nuclear accumulation. In response to AngII, PEA-15 overexpression displays the same functional consequences on ERK1/2 signaling as Akt overactivation. Thus, Akt overactivation prevents the nuclear translocation of ERK1/2 and the AngII-induced proliferation through interaction with and stabilization of endogenous PEA-15.

scholarly journals C9orf72-associated arginine-rich dipeptide repeats induce RNA-dependent nuclear accumulation of Staufen in neurons

2021 ◽  
Author(s):  
Eun Seon Kim ◽  
Chang Geon Chung ◽  
Jeong Hyang Park ◽  
Byung Su Ko ◽  
Sung Soon Park ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Nuclear Accumulation ◽  
Heterozygous Mutation ◽  
Pathological Feature ◽  
Dependent Manner ◽  
Cellular Processes ◽  
Drosophila Model ◽  
Post Transcriptional Regulation

Abstract RNA-binding proteins (RBPs) play essential roles in diverse cellular processes through post-transcriptional regulation of RNAs. The subcellular localization of RBPs is thus under tight control, the breakdown of which is associated with aberrant cytoplasmic accumulation of nuclear RBPs such as TDP-43 and FUS, well-known pathological markers for amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). Here, we report in Drosophila model for ALS/FTD that nuclear accumulation of a cytoplasmic RBP, Staufen, may be a new pathological feature. We found that in Drosophila C4da neurons expressing PR36, one of the arginine-rich dipeptide repeat proteins (DPRs), Staufen accumulated in the nucleus in Importin- and RNA-dependent manner. Notably, expressing Staufen with exogenous NLS—but not with mutated endogenous NLS—potentiated PR-induced dendritic defect, suggesting that nuclear-accumulated Staufen can enhance PR toxicity. PR36 expression increased Fibrillarin staining in the nucleolus, which was enhanced by heterozygous mutation of stau (stau+/−), a gene that codes Staufen. Furthermore, knockdown of fib, which codes Fibrillarin, exacerbated retinal degeneration mediated by PR toxicity, suggesting that increased amount of Fibrillarin by stau+/− is protective. Stau+/− also reduced the amount of PR-induced nuclear-accumulated Staufen and mitigated retinal degeneration and rescued viability of flies expressing PR36. Taken together, our data show that nuclear accumulation of Staufen in neurons may be an important pathological feature contributing to the pathogenesis of ALS/FTD.

scholarly journals Small molecule induces mitochondrial fusion for neuroprotection via targeting CK2 without affecting its conventional kinase activity

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Ke-Wu Zeng ◽  
Jing-Kang Wang ◽  
Li-Chao Wang ◽  
Qiang Guo ◽  
Ting-Ting Liu ◽  
...  
Keyword(s):  
Small Molecule ◽  
Nuclear Translocation ◽  
Fusion Gene ◽  
Artery Occlusion ◽  
Mitochondrial Fusion ◽  
Dependent Manner ◽  
Behavioral Deficits ◽  
Α Subunit ◽  
Cellular Target ◽  
Cerebral Artery Occlusion

AbstractMitochondrial fusion/fission dynamics plays a fundamental role in neuroprotection; however, there is still a severe lack of therapeutic targets for this biological process. Here, we found that the naturally derived small molecule echinacoside (ECH) significantly promotes mitochondrial fusion progression. ECH selectively binds to the previously uncharacterized casein kinase 2 (CK2) α′ subunit (CK2α′) as a direct cellular target, and genetic knockdown of CK2α′ abolishes ECH-mediated mitochondrial fusion. Mechanistically, ECH allosterically regulates CK2α′ conformation to recruit basic transcription factor 3 (BTF3) to form a binary protein complex. Then, the CK2α′/BTF3 complex facilitates β-catenin nuclear translocation to activate TCF/LEF transcription factors and stimulate transcription of the mitochondrial fusion gene Mfn2. Strikingly, in a mouse middle cerebral artery occlusion (MCAO) model, ECH administration was found to significantly improve cerebral injuries and behavioral deficits by enhancing Mfn2 expression in wild-type but not CK2α′+/− mice. Taken together, our findings reveal, for the first time, that CK2 is essential for promoting mitochondrial fusion in a Wnt/β-catenin-dependent manner and suggest that pharmacologically targeting CK2 is a promising therapeutic strategy for ischemic stroke.

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