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Zhang M, Zeng Y, Wang F, Feng H, Liu Q, Li F, Zhao S, Zhao J, Liu Z, Zheng F, Liu H. Effects of the Nonstructural Protein-Nucleolar and Coiled-Body Phosphoprotein 1 Protein Interaction on rRNA Synthesis Through Telomeric Repeat-Binding Factor 2 Regulation Under Nucleolar Stress. AIDS Res Hum Retroviruses 2024; 40:408-416. [PMID: 38062753 DOI: 10.1089/aid.2023.0067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2024] Open
Abstract
To investigate the effects and underlying molecular mechanisms of the interaction between the non-structural protein 1 (NS1) and nucleolar and coiled-body phosphoprotein 1 (NOLC1) on rRNA synthesis through nucleolar telomeric repeat-binding factor 2 (TRF2) under nucleolar stress in avian influenza A virus infection. The analysis of TRF2 ties into the exploration of ribosomal protein L11 (RPL11) and mouse double minute 2 (MDM2) because TRF2 has been found to interact with NOLC1, and the RPL11-MDM2 pathway plays an important role in nucleolar regulation and cellular processes. Both human embryonic kidney 293T cells and human lung adenocarcinoma A549 cells were transfected with the plasmids pCAGGS-HA and pCAGGS-HA-NS1, respectively. In addition, A549 cells were transfected with the plasmids pEGFP-N1, pEGFP-N1-NS1, and pDsRed2-N1-TRF2. The cell cycle was detected by flow cytometry, and coimmunoprecipitation was applied to examine the interactions between different proteins. The effect of NS1 on TRF2 was detected by immunoprecipitation, and the colocalization of NOLC1 and TRF2 or NS1 and TRF2 was visualized by immunofluorescence. Quantitative real-time PCR was conducted to detect the expression of the TRF2 and p21. There is a strong interaction between NOLC1 and TRF2, and the colocalization of NOLC1 and TRF2 in the nucleus. The protein expression of NOLC1 in A549-HA-NS1 cells was lower than that in A549-HA cells, which was accompanied by the upregulated protein expression of p53 in A549-HA-NS1 cells (all p < .05). TRF2 was scattered throughout the nucleus without clear nucleolar aggregation. RPL11 specifically interacted with MDM2 in the NS1 group, and expression of the p21 gene was significantly increased in the HA-NS1 group compared with the HA group (p < .01). NS1 protein can lead to the reduced aggregation of TRF2 in the nucleolus, inhibition of rRNA expression, and cell cycle blockade by interfering with the NOLC1 protein and generating nucleolar stress.
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Affiliation(s)
- Man Zhang
- School of Life Science, Liaoning University, Shenyang, China
| | - Yingyue Zeng
- School of Life Science, Liaoning University, Shenyang, China
- Key Laboratory of Computational Simulation and Information Processing of Biomacromolecules of Liaoning, Shenyang, China
- Shenyang Key Laboratory of Computational Simulation and Information Processing of Biological Macromolecules, Shenyang, China
| | - Fengchao Wang
- School of Life Science, Liaoning University, Shenyang, China
| | - Huawei Feng
- Key Laboratory of Computational Simulation and Information Processing of Biomacromolecules of Liaoning, Shenyang, China
- Shenyang Key Laboratory of Computational Simulation and Information Processing of Biological Macromolecules, Shenyang, China
- School of Pharmacy, Liaoning University, Shenyang, China
- Liaoning Provincial Engineering Laboratory of Molecular Modeling and Design for Drug, Shenyang, China
| | - Qingqing Liu
- School of Life Science, Liaoning University, Shenyang, China
| | - Feng Li
- School of Life Science, Liaoning University, Shenyang, China
| | - Shan Zhao
- School of Life Science, Liaoning University, Shenyang, China
| | - Jian Zhao
- School of Life Science, Liaoning University, Shenyang, China
- Key Laboratory of Computational Simulation and Information Processing of Biomacromolecules of Liaoning, Shenyang, China
- Shenyang Key Laboratory of Computational Simulation and Information Processing of Biological Macromolecules, Shenyang, China
- School of Pharmacy, Liaoning University, Shenyang, China
- Liaoning Provincial Engineering Laboratory of Molecular Modeling and Design for Drug, Shenyang, China
| | - Zhikui Liu
- Liaoning Huikang Testing and Evaluation Technology Co., Shenyang, China
| | - Fangliang Zheng
- School of Life Science, Liaoning University, Shenyang, China
| | - Hongsheng Liu
- Key Laboratory of Computational Simulation and Information Processing of Biomacromolecules of Liaoning, Shenyang, China
- Shenyang Key Laboratory of Computational Simulation and Information Processing of Biological Macromolecules, Shenyang, China
- School of Pharmacy, Liaoning University, Shenyang, China
- Liaoning Provincial Engineering Laboratory of Molecular Modeling and Design for Drug, Shenyang, China
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He W, Sun F, Li W, Du R, Yan S, Liu C. GNL3L promotes autophagy via regulating AMPK signaling in esophageal cancer cells. Med Oncol 2023; 41:29. [PMID: 38148364 DOI: 10.1007/s12032-023-02270-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 11/24/2023] [Indexed: 12/28/2023]
Abstract
Guanine nucleotide-binding protein-like 3-like (GNL3L), a conserved GTP-binding nucleolar protein, participates in regulating cell proliferation, and associates with tumorigenesis and poor prognosis in several kind of cancers. However, the role of GNL3L in modulating autophagy remains unclear. Here, we verified that GNL3L was higher expressed in esophageal cancer (ESCA) biopsies than that in the corresponding normal biopsies by a human ESCA tissue array. Utilizing immunoblotting and real-time PCR assays, we analyzed the expression of GNL3L in several ESCA cell lines, and it was highly expressed in KYSE410 cells and rarely expressed in KYSE150 cells, respectively. GNL3L overexpression promoted cell viability and cell proliferation in KYSE150 cells. On the contrary, silencing of GNL3L resulted in opposite phenotypes in KYSE410 cells. Furthermore, GNL3L level correlated with autophagic flux and influenced the levels of autophagy core proteins. Meanwhile, GNL3L also affected the AMPK signaling pathway, which is a pivotal signaling pathway for autophagy regulation. In the GNL3L-silenced cells, the AMPK agonist AICAR partly rescued the autophagic flux. Inversely, both pharmacologically and genetically deprivation of AMPK attenuated the autophagic flux induced by GNL3L overexpression. Moreover, AMPK activity alteration influenced the effect of GNL3L in regulating cell proliferation. Collectively, these findings suggest that GNL3L positively regulates cell proliferation and autophagy in ESCA cells via regulating the AMPK signaling, making itself a promising therapeutic target for ESCA.
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Affiliation(s)
- Weiting He
- School of Clinical Medicine, Bengbu Medical College, Bengbu, 233030, China
| | - Fengyao Sun
- Institute of Precision Medicine, Precision Medicine Laboratory for Chronic Non-Communicable Diseases of Shandong Province, Jining Medical University, Jining, 272067, China
| | - Wen Li
- Institute of Precision Medicine, Precision Medicine Laboratory for Chronic Non-Communicable Diseases of Shandong Province, Jining Medical University, Jining, 272067, China
| | - Ruihang Du
- Institute of Precision Medicine, Precision Medicine Laboratory for Chronic Non-Communicable Diseases of Shandong Province, Jining Medical University, Jining, 272067, China
| | - Siyuan Yan
- Institute of Precision Medicine, Precision Medicine Laboratory for Chronic Non-Communicable Diseases of Shandong Province, Jining Medical University, Jining, 272067, China.
| | - Changqing Liu
- School of Clinical Medicine, Bengbu Medical College, Bengbu, 233030, China.
- School of Laboratory Medicine, School of Life Sciences, Bengbu Medical College, Bengbu, 233030, China.
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Liu P, Guo W, Su Y, Chen C, Ma Y, Ma P, Chen C, Lv X. Multi-Omics Analysis of GNL3L Expression, Prognosis, and Immune Value in Pan-Cancer. Cancers (Basel) 2022; 14:cancers14194595. [PMID: 36230520 PMCID: PMC9558978 DOI: 10.3390/cancers14194595] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Guanine nucleotide-binding protein-like 3-like (GNL3L) is a novel GTP-binding nucleolar protein. In this study, we analyzed the expression, prognosis, and immune roles of GNL3L in pan-cancer from multiple omics analyses. The final results showed that GNL3L is differentially expressed in a variety of cancers, plays a prognostic role, and has good immune value. Moreover, GNL3L may affect the occurrence of cancer through processes such as ribonucleoprotein, ribosomal RNA processing, and cell proliferation. At the same time, we established an esophageal cancer (ESCA) prediction model with strong predictive ability and proved that GNL3L can significantly affect the proliferation ability of esophageal cancer cells through clone formation assays. In conclusion, GNL3L is an important biomarker. Abstract Guanine nucleotide-binding protein-like 3-like protein (GNL3L) is a novel, evolutionarily conserved, GTP-binding nucleolar protein. This study aimed to investigate the expression, prognosis, and immune value of GNL3L in pan-cancer from multiple omics analyses. Firstly, the expression and prognostic value of GNL3L in pan-cancer were discussed using the TIMER2 database, the GEPIA database, the cBioportal database, COX regression analysis, and enrichment analysis. The association of GNL3L with tumor mutational burden (TMB), tumor microsatellite instability (MSI), mismatch repair (MMR) genes, and immune cells was then analyzed. Finally, an esophageal cancer (ESCA) prediction model was established, and GNL3L clone formation assays were performed. The final results showed that GNL3L is differentially expressed in the vast majority of cancers, is associated with the prognosis of various cancers, and may affect cancer occurrence through processes such as ribonucleoprotein, ribosomal RNA processing, and cell proliferation. At the same time, it was found that the correlation between GNL3L and TMB, MSI, MMR, and various immune cells is significant. The established ESCA prediction model had a strong predictive ability, and GNL3L could significantly affect the proliferation of esophageal cancer cells. In conclusion, GNL3L may serve as an important prognostic biomarker and play an immunomodulatory role in tumors.
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Affiliation(s)
- Pei Liu
- College of Information Science, Engineering Xinjiang University, Urumqi 830046, China
- College of Software, Xinjiang University, Urumqi 830046, China
| | - Wenjia Guo
- Xinjiang Medical University Affiliated Tumor Hospital, Urumqi 830011, China
| | - Ying Su
- College of Software, Xinjiang University, Urumqi 830046, China
| | - Chen Chen
- College of Information Science, Engineering Xinjiang University, Urumqi 830046, China
- Xinjiang Cloud Computing Application Laboratory, Karamay 834099, China
| | - Yuhua Ma
- Karamay Central Hospital, Karamay 834099, China
| | - Ping Ma
- College of Software, Xinjiang University, Urumqi 830046, China
| | - Cheng Chen
- College of Software, Xinjiang University, Urumqi 830046, China
- Correspondence: (C.C.); (X.L.)
| | - Xiaoyi Lv
- College of Software, Xinjiang University, Urumqi 830046, China
- Correspondence: (C.C.); (X.L.)
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Yuan F, Xu C, Li G, Tong T. Nucleolar TRF2 attenuated nucleolus stress-induced HCC cell-cycle arrest by altering rRNA synthesis. Cell Death Dis 2018; 9:518. [PMID: 29725012 PMCID: PMC5938709 DOI: 10.1038/s41419-018-0572-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 01/14/2023]
Abstract
The nucleolus is an important organelle that is responsible for the biogenesis of ribosome RNA (rRNA) and ribosomal subunits assembly. It is also deemed to be the center of metabolic control, considering the critical role of ribosomes in protein translation. Perturbations of rRNA synthesis are closely related to cell proliferation and tumor progression. Telomeric repeat-binding factor 2 (TRF2) is a member of shelterin complex that is responsible for telomere DNA protection. Interestingly, it was recently reported to localize in the nucleolus of human cells in a cell-cycle-dependent manner, while the underlying mechanism and its role on the nucleolus remained unclear. In this study, we found that nucleolar and coiled-body phosphoprotein 1 (NOLC1), a nucleolar protein that is responsible for the nucleolus construction and rRNA synthesis, interacted with TRF2 and mediated the shuttle of TRF2 between the nucleolus and nucleus. Abating the expression of NOLC1 decreased the nucleolar-resident TRF2. Besides, the nucleolar TRF2 could bind rDNA and promoted rRNA transcription. Furthermore, in hepatocellular carcinoma (HCC) cell lines HepG2 and SMMC7721, TRF2 overexpression participated in the nucleolus stress-induced rRNA inhibition and cell-cycle arrest.
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Affiliation(s)
- Fuwen Yuan
- Research Center on Aging, Department of Medical Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Chenzhong Xu
- Research Center on Aging, Department of Medical Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Guodong Li
- Research Center on Aging, Department of Medical Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China
| | - Tanjun Tong
- Research Center on Aging, Department of Medical Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University, Beijing, China.
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5
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Nucleolar and coiled-body phosphoprotein 1 (NOLC1) regulates the nucleolar retention of TRF2. Cell Death Discov 2017; 3:17043. [PMID: 28875039 PMCID: PMC5582526 DOI: 10.1038/cddiscovery.2017.43] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/24/2017] [Accepted: 06/03/2017] [Indexed: 01/24/2023] Open
Abstract
Telomeric repeat-binding factor 2 (TRF2) was reported to localize in the nucleolus of human cells in a cell cycle-dependent manner; however, the underlying mechanism remains unclear. Here, we found that nucleolar and coiled-body phosphoprotein 1 (NOLC1) interacted with TRF2 and mediated the shuttling of TRF2 between the nucleolus and nucleus in human 293T and HepG2 cells. Ablation of NOLC1 expression increased the number of nuclear TRF2 foci and decreased the nucleolar level of TRF2. Conversely, NOLC1 overexpression promoted the nucleolar accumulation of TRF2. NOLC1 overexpression also increased the number of 53BP1 foci and induced the DNA damage response. In addition, co-expression of TRF2 rescued NOLC1 overexpression-induced cell cycle arrest and apoptosis.
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Hariharan N, Sussman MA. Stressing on the nucleolus in cardiovascular disease. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1842:798-801. [PMID: 24514103 PMCID: PMC3972279 DOI: 10.1016/j.bbadis.2013.09.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/18/2013] [Indexed: 12/23/2022]
Abstract
The nucleolus is a multifunctional organelle with multiple roles involving cell proliferation, growth, survival, ribosome biogenesis and stress response signaling. Alteration of nucleolar morphology and architecture signifies an early response to increased cellular stress. This review briefly summarizes nucleolar response to cardiac stress signals and details the role played by nucleolar proteins in cardiovascular pathophysiology. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Nirmala Hariharan
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, CA 92182, USA
| | - Mark A Sussman
- Department of Biology, San Diego State University Heart Institute, San Diego State University, San Diego, CA 92182, USA.
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Nucleolar organization, ribosomal DNA array stability, and acrocentric chromosome integrity are linked to telomere function. PLoS One 2014; 9:e92432. [PMID: 24662969 PMCID: PMC3963894 DOI: 10.1371/journal.pone.0092432] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 02/21/2014] [Indexed: 12/16/2022] Open
Abstract
The short arms of the ten acrocentric human chromosomes share several repetitive DNAs, including ribosomal RNA genes (rDNA). The rDNA arrays correspond to nucleolar organizing regions that coalesce each cell cycle to form the nucleolus. Telomere disruption by expressing a mutant version of telomere binding protein TRF2 (dnTRF2) causes non-random acrocentric fusions, as well as large-scale nucleolar defects. The mechanisms responsible for acrocentric chromosome sensitivity to dysfunctional telomeres are unclear. In this study, we show that TRF2 normally associates with the nucleolus and rDNA. However, when telomeres are crippled by dnTRF2 or RNAi knockdown of TRF2, gross nucleolar and chromosomal changes occur. We used the controllable dnTRF2 system to precisely dissect the timing and progression of nucleolar and chromosomal instability induced by telomere dysfunction, demonstrating that nucleolar changes precede the DNA damage and morphological changes that occur at acrocentric short arms. The rDNA repeat arrays on the short arms decondense, and are coated by RNA polymerase I transcription binding factor UBF, physically linking acrocentrics to one another as they become fusogenic. These results highlight the importance of telomere function in nucleolar stability and structural integrity of acrocentric chromosomes, particularly the rDNA arrays. Telomeric stress is widely accepted to cause DNA damage at chromosome ends, but our findings suggest that it also disrupts chromosome structure beyond the telomere region, specifically within the rDNA arrays located on acrocentric chromosomes. These results have relevance for Robertsonian translocation formation in humans and mechanisms by which acrocentric-acrocentric fusions are promoted by DNA damage and repair.
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8
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Lee J, Sammond DW, Fiorini Z, Saludes JP, Resch MG, Hao B, Wang W, Yin H, Liu X. Computationally designed peptide inhibitors of the ubiquitin E3 ligase SCF(Fbx4). Chembiochem 2013; 14:445-51. [PMID: 23401343 DOI: 10.1002/cbic.201200777] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Indexed: 11/07/2022]
Abstract
A structure-based computational approach was used to rationally design peptide inhibitors that can target an E3 ligase (SCF(Fbx4) )-substrate (TRF1) interface and subsequent ubiquitylation. Characterization of the inhibitors demonstrates that our sequence-optimization protocol results in an increase in peptide-TRF1 affinity without compromising peptide-protein specificity.
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Affiliation(s)
- Junglim Lee
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado, JSCBB 3415 Colorado Avenue, Boulder, CO 80309-0215, USA
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Hsu JK, Lin T, Tsai RYL. Nucleostemin prevents telomere damage by promoting PML-IV recruitment to SUMOylated TRF1. ACTA ACUST UNITED AC 2012; 197:613-24. [PMID: 22641345 PMCID: PMC3365494 DOI: 10.1083/jcb.201109038] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A novel telomere-protection mechanism relies upon nucleostemin-mediated recruitment of PML-IV to telomeres and subsequent recruitment of RAD51 in both ALT and telomerase-active cells. Continuously dividing cells must be protected from telomeric and nontelomeric DNA damage in order to maintain their proliferative potential. Here, we report a novel telomere-protecting mechanism regulated by nucleostemin (NS). NS depletion increased the number of telomere damage foci in both telomerase-active (TA+) and alternative lengthening of telomere (ALT) cells and decreased the percentage of damaged telomeres associated with ALT-associated PML bodies (APB) and the number of APB in ALT cells. Mechanistically, NS could promote the recruitment of PML-IV to SUMOylated TRF1 in TA+ and ALT cells. This event was stimulated by DNA damage. Supporting the importance of NS and PML-IV in telomere protection, we demonstrate that loss of NS or PML-IV increased the frequency of telomere damage and aberration, reduced telomeric length, and perturbed the TRF2ΔBΔM-induced telomeric recruitment of RAD51. Conversely, overexpression of either NS or PML-IV protected ALT and TA+ cells from telomere damage. This work reveals a novel mechanism in telomere protection.
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Affiliation(s)
- Joseph K Hsu
- Center for Cancer and Stem Cell Biology, Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX 77030, USA
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Stixová L, Matula P, Kozubek S, Gombitová A, Cmarko D, Raška I, Bártová E. Trajectories and nuclear arrangement of PML bodies are influenced by A-type lamin deficiency. Biol Cell 2012; 104:418-32. [PMID: 22443097 DOI: 10.1111/boc.201100053] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 03/16/2012] [Indexed: 01/08/2023]
Abstract
BACKGROUND INFORMATION Promyelocytic leukaemia (PML) bodies are specific nuclear structures with functional significance for acute promyelocytic leukaemia. In this study, we analysed the trajectories of PML bodies using single-particle tracking. RESULTS We observed that the recovery of PML protein after photobleaching was ATP dependent in both wild-type (wt) and A-type lamin-deficient cells. The movement of PML bodies was faster and the nuclear area occupied by particular PML bodies was larger in A-type lamin-deficient fibroblasts compared with their wt counterparts. Moreover, dysfunction of the LMNA gene increased the frequency of mutual interactions between individual PML bodies and influenced the morphology of these domains at the ultrastructural level. As a consequence of A-type lamin deficiency, PML protein accumulated in nuclear blebs and frequently appeared at the nuclear periphery. CONCLUSIONS We suggest that the physiological function of lamin A proteins is important for events that occur in the compartment of PML bodies. This observation was confirmed in other experimental models characterised by lamin changes, including apoptosis or the differentiation of mouse embryonic stem cells.
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Affiliation(s)
- Lenka Stixová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, 61265 Brno, Czech Republic
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Meng L, Hsu JK, Zhu Q, Lin T, Tsai RYL. Nucleostemin inhibits TRF1 dimerization and shortens its dynamic association with the telomere. J Cell Sci 2011; 124:3706-14. [PMID: 22045740 DOI: 10.1242/jcs.089672] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
TRF1 is a key component of the telomere-capping complex and binds double-strand telomeric DNA as homodimers. So far, it is not clear whether TRF1 dimerization coincides with its telomere binding or is actively controlled before it binds the telomere, and in the latter case, how this event might affect its telomere association. We previously found that TRF1 dimerization and its telomere binding can be increased by GNL3L, which is the vertebrate paralogue of nucleostemin (NS). Here, we show that NS and GNL3L bind TRF1 directly but competitively through two separate domains of TRF1. In contrast to GNL3L, NS prevents TRF1 dimerization through a mechanism not determined by its ability to displace TRF1-bound GNL3L. Furthermore, NS is capable of shortening the dynamic association of TRF1 with the telomere in normal and TRF2(ΔBΔM)-induced telomere-damaged cells without affecting the amount of telomere-bound TRF1 proteins in vivo. Importantly, NS displays a protective function against the formation of telomere-dysfunction-induced foci. This work demonstrates that TRF1 dimerization is actively and oppositely regulated by NS and GNL3L extrachromosomally. Changing the relative amount of TRF1 monomers versus dimers in the nucleoplasm might affect the dynamic association of TRF1 with the telomere and the repair of damaged telomeres.
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Affiliation(s)
- Lingjun Meng
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, Texas 77030, USA
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