1
|
Statello L, Fernandez-Justel JM, González J, Montes M, Ranieri A, Goñi E, Mas AM, Huarte M. The chromatin-associated lncREST ensures effective replication stress response by promoting the assembly of fork signaling factors. Nat Commun 2024; 15:978. [PMID: 38302450 PMCID: PMC10834948 DOI: 10.1038/s41467-024-45183-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 01/17/2024] [Indexed: 02/03/2024] Open
Abstract
Besides the well-characterized protein network involved in the replication stress response, several regulatory RNAs have been shown to play a role in this critical process. However, it has remained elusive whether they act locally at the stressed forks. Here, by investigating the RNAs localizing on chromatin upon replication stress induced by hydroxyurea, we identified a set of lncRNAs upregulated in S-phase and controlled by stress transcription factors. Among them, we demonstrate that the previously uncharacterized lncRNA lncREST (long non-coding RNA REplication STress) is transcriptionally controlled by p53 and localizes at stressed replication forks. LncREST-depleted cells experience sustained replication fork progression and accumulate un-signaled DNA damage. Under replication stress, lncREST interacts with the protein NCL and assists in engaging its interaction with RPA. The loss of lncREST is associated with a reduced NCL-RPA interaction and decreased RPA on chromatin, leading to defective replication stress signaling and accumulation of mitotic defects, resulting in apoptosis and a reduction in tumorigenic potential of cancer cells. These findings uncover the function of a lncRNA in favoring the recruitment of replication proteins to sites of DNA replication.
Collapse
Affiliation(s)
- Luisa Statello
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain.
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain.
| | - José Miguel Fernandez-Justel
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Jovanna González
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Marta Montes
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Alessia Ranieri
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Enrique Goñi
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Aina M Mas
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain
| | - Maite Huarte
- Center for Applied Medical Research, University of Navarra, Pio XII 55 Ave, 11 31008, Pamplona, Spain.
- Institute of Health Research of Navarra (IdiSNA), Cancer Center Clínica Universidad de Navarra (CCUN), Pamplona, Spain.
| |
Collapse
|
2
|
Fousek-Schuller VJ, Borgstahl GEO. The Intriguing Mystery of RPA Phosphorylation in DNA Double-Strand Break Repair. Genes (Basel) 2024; 15:167. [PMID: 38397158 PMCID: PMC10888239 DOI: 10.3390/genes15020167] [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: 12/20/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/25/2024] Open
Abstract
Human Replication Protein A (RPA) was historically discovered as one of the six components needed to reconstitute simian virus 40 DNA replication from purified components. RPA is now known to be involved in all DNA metabolism pathways that involve single-stranded DNA (ssDNA). Heterotrimeric RPA comprises several domains connected by flexible linkers and is heavily regulated by post-translational modifications (PTMs). The structure of RPA has been challenging to obtain. Various structural methods have been applied, but a complete understanding of RPA's flexible structure, its function, and how it is regulated by PTMs has yet to be obtained. This review will summarize recent literature concerning how RPA is phosphorylated in the cell cycle, the structural analysis of RPA, DNA and protein interactions involving RPA, and how PTMs regulate RPA activity and complex formation in double-strand break repair. There are many holes in our understanding of this research area. We will conclude with perspectives for future research on how RPA PTMs control double-strand break repair in the cell cycle.
Collapse
Affiliation(s)
| | - Gloria E. O. Borgstahl
- Eppley Institute for Research in Cancer & Allied Diseases, UNMC, Omaha, NE 68198-6805, USA
| |
Collapse
|
3
|
Xiao CD, Zhong MQ, Gao Y, Yang ZL, Jia MH, Hu XH, Xu Y, Shen XC. A Unique G-Quadruplex Aptamer: A Novel Approach for Cancer Cell Recognition, Cell Membrane Visualization, and RSV Infection Detection. Int J Mol Sci 2023; 24:14344. [PMID: 37762645 PMCID: PMC10531985 DOI: 10.3390/ijms241814344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Surface staining has emerged as a rapid technique for applying external stains to trace cellular identities in diverse populations. In this study, we developed a distinctive aptamer with selective binding to cell surface nucleolin (NCL), bypassing cytoplasmic internalization. Conjugation of the aptamer with a FAM group facilitated NCL visualization on live cell surfaces with laser confocal microscopy. To validate the aptamer-NCL interaction, we employed various methods, including the surface plasmon resonance, IHC-based flow cytometry, and electrophoretic mobility shift assay. The G-quadruplex formations created by aptamers were confirmed with a nuclear magnetic resonance and an electrophoretic mobility shift assay utilizing BG4, a G-quadruplex-specific antibody. Furthermore, the aptamer exhibited discriminatory potential in distinguishing between cancerous and normal cells using flow cytometry. Notably, it functioned as a dynamic probe, allowing real-time monitoring of heightened NCL expression triggered by a respiratory syncytial virus (RSV) on normal cell surfaces. This effect was subsequently counteracted with dsRNA transfection and suppressed the NCL expression; thus, emphasizing the dynamic attributes of the probe. These collective findings highlight the robust versatility of our aptamer as a powerful tool for imaging cell surfaces, holding promising implications for cancer cell identification and the detection of RSV infections.
Collapse
Affiliation(s)
- Chao-Da Xiao
- State Key Laboratory of Functions and Applications of Medicinal Plants, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China; (M.-Q.Z.); (Y.G.); (Z.-L.Y.); (M.-H.J.); (X.-H.H.)
- The Key Laboratory of Optimal Utilization of Natural Medicine Resources, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China
| | - Ming-Qing Zhong
- State Key Laboratory of Functions and Applications of Medicinal Plants, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China; (M.-Q.Z.); (Y.G.); (Z.-L.Y.); (M.-H.J.); (X.-H.H.)
- The Key Laboratory of Optimal Utilization of Natural Medicine Resources, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China
| | - Yue Gao
- State Key Laboratory of Functions and Applications of Medicinal Plants, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China; (M.-Q.Z.); (Y.G.); (Z.-L.Y.); (M.-H.J.); (X.-H.H.)
| | - Zheng-Lin Yang
- State Key Laboratory of Functions and Applications of Medicinal Plants, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China; (M.-Q.Z.); (Y.G.); (Z.-L.Y.); (M.-H.J.); (X.-H.H.)
| | - Meng-Hao Jia
- State Key Laboratory of Functions and Applications of Medicinal Plants, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China; (M.-Q.Z.); (Y.G.); (Z.-L.Y.); (M.-H.J.); (X.-H.H.)
| | - Xiao-Hui Hu
- State Key Laboratory of Functions and Applications of Medicinal Plants, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China; (M.-Q.Z.); (Y.G.); (Z.-L.Y.); (M.-H.J.); (X.-H.H.)
| | - Yan Xu
- Division of Chemistry, Department of Medical Sciences, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan;
| | - Xiang-Chun Shen
- State Key Laboratory of Functions and Applications of Medicinal Plants, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China; (M.-Q.Z.); (Y.G.); (Z.-L.Y.); (M.-H.J.); (X.-H.H.)
- The Key Laboratory of Optimal Utilization of Natural Medicine Resources, School of Pharmaceutical Sciences, Guizhou Medical University, Guiyang 550025, China
| |
Collapse
|
4
|
Muñoz-Díaz E, Sáez-Vásquez J. Nuclear dynamics: Formation of bodies and trafficking in plant nuclei. FRONTIERS IN PLANT SCIENCE 2022; 13:984163. [PMID: 36082296 PMCID: PMC9445803 DOI: 10.3389/fpls.2022.984163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/04/2022] [Indexed: 06/01/2023]
Abstract
The existence of the nucleus distinguishes prokaryotes and eukaryotes. Apart from containing most of the genetic material, the nucleus possesses several nuclear bodies composed of protein and RNA molecules. The nucleus is separated from the cytoplasm by a double membrane, regulating the trafficking of molecules in- and outwards. Here, we investigate the composition and function of the different plant nuclear bodies and molecular clues involved in nuclear trafficking. The behavior of the nucleolus, Cajal bodies, dicing bodies, nuclear speckles, cyclophilin-containing bodies, photobodies and DNA damage foci is analyzed in response to different abiotic stresses. Furthermore, we research the literature to collect the different protein localization signals that rule nucleocytoplasmic trafficking. These signals include the different types of nuclear localization signals (NLSs) for nuclear import, and the nuclear export signals (NESs) for nuclear export. In contrast to these unidirectional-movement signals, the existence of nucleocytoplasmic shuttling signals (NSSs) allows bidirectional movement through the nuclear envelope. Likewise, nucleolar signals are also described, which mainly include the nucleolar localization signals (NoLSs) controlling nucleolar import. In contrast, few examples of nucleolar export signals, called nucleoplasmic localization signals (NpLSs) or nucleolar export signals (NoESs), have been reported. The existence of consensus sequences for these localization signals led to the generation of prediction tools, allowing the detection of these signals from an amino acid sequence. Additionally, the effect of high temperatures as well as different post-translational modifications in nuclear and nucleolar import and export is discussed.
Collapse
Affiliation(s)
- Eduardo Muñoz-Díaz
- Centre National de la Recherche Scientifique (CNRS), Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
- Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
| | - Julio Sáez-Vásquez
- Centre National de la Recherche Scientifique (CNRS), Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
- Univ. Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR 5096, Perpignan, France
| |
Collapse
|
5
|
Yangngam S, Prasopsiri J, Hatthakarnkul P, Thongchot S, Thuwajit P, Yenchitsomanus PT, Edwards J, Thuwajit C. Cellular localization of nucleolin determines the prognosis in cancers: a meta-analysis. J Mol Med (Berl) 2022; 100:1145-1157. [PMID: 35861882 PMCID: PMC9329415 DOI: 10.1007/s00109-022-02228-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Revised: 06/09/2022] [Accepted: 06/22/2022] [Indexed: 12/01/2022]
Abstract
Nucleolin (NCL) is a multifunctional protein expressed in the nucleus, cytoplasm, and cell membrane. Overexpression of NCL has a controversial role as a poor prognostic marker in cancers. In this study, a meta-analysis was performed to evaluate the prognostic value of NCL in different subcellular localizations (cytoplasmic (CyNCL) and nuclear (NuNCL)) across a range of cancers. PubMed was searched for relevant publications. Data were extracted and analyzed from 12 studies involving 1221 patients with eight cancer types. The results revealed high total NCL was significantly associated with poor overall survival (OS) (HR = 2.85 (1.94, 4.91), p < 0.00001, I2 = 59%) and short disease-free survival (DFS) (HR = 3.57 (2.76, 4.62), p < 0.00001, I2 = 2%). High CyNCL was significantly associated with poor OS (HR = 4.32 (3.01, 6.19), p < 0.00001, I2 = 0%) and short DFS (HR = 3.00 (2.17, 4.15), p < 0.00001, I2 = 0%). In contrast, high NuNCL correlated with increased patient OS (HR = 0.42 (0.20, 0.86), p = 0.02, I2 = 66%), with no significant correlation to DFS observed (HR = 0.46 (0.19, 1.14), p = 0.09, I2 = 57%). This study supports the role of subcellular NCL as a poor prognostic cancer biomarker.
Collapse
Affiliation(s)
- Supaporn Yangngam
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Jaturawitt Prasopsiri
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Phimmada Hatthakarnkul
- Biomedical Sciences Graduate Program, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.,Institute of Cancer Sciences, University of Glasgow, Wolfson Wohl Cancer Research Centre, Garscube Estate, Glasgow, G61 1QH, UK
| | - Suyanee Thongchot
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.,Siriraj Center of Research Excellence for Cancer Immunotherapy (SiCORE-CIT), Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Peti Thuwajit
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Pa-Thai Yenchitsomanus
- Siriraj Center of Research Excellence for Cancer Immunotherapy (SiCORE-CIT), Research Department, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand
| | - Joanne Edwards
- Institute of Cancer Sciences, University of Glasgow, Wolfson Wohl Cancer Research Centre, Garscube Estate, Glasgow, G61 1QH, UK
| | - Chanitra Thuwajit
- Department of Immunology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
| |
Collapse
|
6
|
Feng S, Manley JL. Replication protein A associates with nucleolar R loops and regulates rRNA transcription and nucleolar morphology. Genes Dev 2021; 35:1579-1594. [PMID: 34819354 PMCID: PMC8653787 DOI: 10.1101/gad.348858.121] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/22/2021] [Indexed: 11/24/2022]
Abstract
Here, Feng and Manley report novel functions of the DNA replication and repair factor replication protein A (RPA) in control of nucleolar homeostasis. Their findings both indicate new roles for RPA in nucleoli through pre-rRNA transcriptional control and also emphasize that RPA function in nucleolar homeostasis is linked to R-loop resolution under both physiological and pathological conditions. The nucleolus is an important cellular compartment in which ribosomal RNAs (rRNAs) are transcribed and where certain stress pathways that are crucial for cell growth are coordinated. Here we report novel functions of the DNA replication and repair factor replication protein A (RPA) in control of nucleolar homeostasis. We show that loss of the DNA:RNA helicase senataxin (SETX) promotes RPA nucleolar localization, and that this relocalization is dependent on the presence of R loops. Notably, this nucleolar RPA phenotype was also observed in the presence of camptothecin (CPT)-induced genotoxic stress, as well as in SETX-deficient AOA2 patient fibroblasts. Extending these results, we found that RPA is recruited to rDNA following CPT treatment, where RPA prevents R-loop-induced DNA double-strand breaks. Furthermore, we show that loss of RPA significantly decreased 47S pre-rRNA levels, which was accompanied by increased expression of both RNAP II-mediated “promoter and pre-rRNA antisense” RNA as well as RNAP I-transcribed intragenic spacer RNAs. Finally, and likely reflecting the above, we found that loss of RPA promoted nucleolar structural disorganization, characterized by the appearance of reduced size nucleoli. Our findings both indicate new roles for RPA in nucleoli through pre-rRNA transcriptional control and also emphasize that RPA function in nucleolar homeostasis is linked to R-loop resolution under both physiological and pathological conditions.
Collapse
Affiliation(s)
- Shuang Feng
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| |
Collapse
|
7
|
Molecular coevolution of nuclear and nucleolar localization signals inside basic domain of HIV-1 Tat. J Virol 2021; 96:e0150521. [PMID: 34613791 DOI: 10.1128/jvi.01505-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
During evolution, viruses had to adapt to an increasingly complex environment of eukaryotic cells. Viral proteins that need to enter the cell nucleus or associate with nucleoli possess nuclear localization signals (NLSs) and nucleolar localization signals (NoLSs) for nuclear and nucleolar accumulation, respectively. As viral proteins are relatively small, acquisition of novel sequences seems to be a more complicated task for viruses than for eukaryotes. Here, we carried out a comprehensive analysis of the basic domain (BD) of HIV-1 Tat to show how viral proteins might evolve with NLSs and NoLSs without an increase in protein size. The HIV-1 Tat BD is involved in several functions, the most important being the transactivation of viral transcription. The BD also functions as an NLS, although it is substantially longer than a typical NLS. It seems that different regions in the BD could function as NLSs due to its enrichment with positively charged amino acids. Additionally, the high positive net charge inevitably causes the BD to function as an NoLS through a charge-specific mechanism. The integration of NLSs and NoLSs into functional domains enriched with positively charged amino acids might be a mechanism that allows the condensation of different functional sequences in small protein regions and, as a result, to reduce protein size, influencing the origin and evolution of NLSs and NoLSs in viruses. IMPORTANCE Here, we investigated the molecular mechanism of NLS and NoLS integration into the basic domain of HIV-1 Tat (49RKKRRQRRR57), and found that these two supplementary functions (i.e., function of NLS and NoLS) are embedded in the basic domain amino acid sequence. The integration of NLSs and NoLSs into functional domains of viral proteins enriched with positively charged amino acids is a mechanism that allows the concentration of different functions within small protein regions. Integration of NLS and NoLS into functional protein domains might have influenced the viral evolution, as this could prevent an increase in the protein size.
Collapse
|
8
|
Wang L, Li J, Zhou H, Zhang W, Gao J, Zheng P. A novel lncRNA Discn fine-tunes replication protein A (RPA) availability to promote genomic stability. Nat Commun 2021; 12:5572. [PMID: 34552092 PMCID: PMC8458541 DOI: 10.1038/s41467-021-25827-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 08/31/2021] [Indexed: 11/24/2022] Open
Abstract
RPA is a master regulator of DNA metabolism and RPA availability acts as a rate-limiting factor. While numerous studies focused on the post-translational regulations of RPA for its functions, little is known regarding how RPA availability is controlled. Here we identify a novel lncRNA Discn as the guardian of RPA availability in stem cells. Discn is induced upon genotoxic stress and binds to neucleolin (NCL) in the nucleolus. This prevents NCL from translocation into nucleoplasm and avoids undesirable NCL-mediated RPA sequestration. Thus, Discn-NCL-RPA pathway preserves a sufficient RPA pool for DNA replication stress response and repair. Discn loss causes massive genome instability in mouse embryonic stem cells and neural stem/progenigor cells. Mice depleted of Discn display newborn death and brain dysfunctions due to DNA damage accumulation and associated inflammatory reactions. Our findings uncover a key regulator of DNA metabolism and provide new clue to understand the chemoresistance in cancer treatment.
Collapse
Affiliation(s)
- Lin Wang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China
- Yunnan Key Laboratory of Animal Reproduction, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China
| | - Jingzheng Li
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China
- Yunnan Key Laboratory of Animal Reproduction, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China
- University of Chinese Academy of Sciences, Beijing, 101408, China
| | - Hu Zhou
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Weidao Zhang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China
- Yunnan Key Laboratory of Animal Reproduction, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China
| | - Jing Gao
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Ping Zheng
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China.
- Yunnan Key Laboratory of Animal Reproduction, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China.
- KIZ/CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China.
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China.
| |
Collapse
|
9
|
Dagar S, Pushpa K, Pathak D, Samaddar S, Saxena A, Banerjee S, Mylavarapu SVS. Nucleolin regulates 14-3-3ζ mRNA and promotes cofilin phosphorylation to induce tunneling nanotube formation. FASEB J 2021; 35:e21199. [PMID: 33222276 DOI: 10.1096/fj.202001152r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 10/19/2020] [Accepted: 11/02/2020] [Indexed: 12/17/2023]
Abstract
Tunneling nanotubes (TNTs) mediate intercellular communication between animal cells in health and disease, but the mechanisms of their biogenesis and function are poorly understood. Here we report that the RNA-binding protein (RBP) nucleolin, which interacts with the known TNT-inducing protein MSec, is essential for TNT formation in mammalian cells. Nucleolin, through its RNA-binding domains (RBDs), binds to and maintains the cytosolic levels of 14-3-3ζ mRNA, and is, therefore, required for TNT formation. A specific region of the 3'-untranslated region (UTR) of the 14-3-3ζ mRNA is likely to be involved in its regulation by nucleolin. Functional complementation experiments suggest that nucleolin and 14-3-3ζ form a linear signaling axis that promotes the phosphorylation and inactivation of the F-actin depolymerization factor cofilin to induce TNT formation. MSec also similarly inactivates cofilin, but potentiates TNT formation independent of the nucleolin-14-3-3ζ axis, despite biochemically interacting with both proteins. We show that 14-3-3ζ and nucleolin are required for the formation of TNTs between primary mouse neurons and astrocytes and in multiple other mammalian cell types. We also report that the Caenorhabditis elegans orthologs of 14-3-3ζ and MSec regulate the size and architecture of the TNT-like cellular protrusions of the distal tip cell (DTC), the germline stem cell niche in the gonad. Our study demonstrates a novel and potentially conserved mRNA-guided mechanism of TNT formation through the maintenance of cellular 14-3-3ζ mRNA levels by the RBP nucleolin.
Collapse
Affiliation(s)
- Sunayana Dagar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, India
- Affiliated to the Kalinga Institute of Industrial Technology, Bhubaneswar, India
| | - Kumari Pushpa
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, India
| | - Diksha Pathak
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, India
| | | | - Anjana Saxena
- Biology Department, Brooklyn College AND Biology and Biochemistry Programs, Graduate Center, CUNY, New York, NY, USA
| | | | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, India
- Affiliated to the Kalinga Institute of Industrial Technology, Bhubaneswar, India
| |
Collapse
|
10
|
Caldwell CC, Spies M. Dynamic elements of replication protein A at the crossroads of DNA replication, recombination, and repair. Crit Rev Biochem Mol Biol 2020; 55:482-507. [PMID: 32856505 PMCID: PMC7821911 DOI: 10.1080/10409238.2020.1813070] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/18/2020] [Accepted: 08/18/2020] [Indexed: 01/19/2023]
Abstract
The heterotrimeric eukaryotic Replication protein A (RPA) is a master regulator of numerous DNA metabolic processes. For a long time, it has been viewed as an inert protector of ssDNA and a platform for assembly of various genome maintenance and signaling machines. Later, the modular organization of the RPA DNA binding domains suggested a possibility for dynamic interaction with ssDNA. This modular organization has inspired several models for the RPA-ssDNA interaction that aimed to explain how RPA, the high-affinity ssDNA binding protein, is replaced by the downstream players in DNA replication, recombination, and repair that bind ssDNA with much lower affinity. Recent studies, and in particular single-molecule observations of RPA-ssDNA interactions, led to the development of a new model for the ssDNA handoff from RPA to a specific downstream factor where not only stability and structural rearrangements but also RPA conformational dynamics guide the ssDNA handoff. Here we will review the current knowledge of the RPA structure, its dynamic interaction with ssDNA, and how RPA conformational dynamics may be influenced by posttranslational modification and proteins that interact with RPA, as well as how RPA dynamics may be harnessed in cellular decision making.
Collapse
Affiliation(s)
- Colleen C. Caldwell
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| | - Maria Spies
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242
| |
Collapse
|
11
|
Dueva R, Iliakis G. Replication protein A: a multifunctional protein with roles in DNA replication, repair and beyond. NAR Cancer 2020; 2:zcaa022. [PMID: 34316690 PMCID: PMC8210275 DOI: 10.1093/narcan/zcaa022] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/23/2020] [Accepted: 08/27/2020] [Indexed: 02/07/2023] Open
Abstract
Single-stranded DNA (ssDNA) forms continuously during DNA replication and is an important intermediate during recombination-mediated repair of damaged DNA. Replication protein A (RPA) is the major eukaryotic ssDNA-binding protein. As such, RPA protects the transiently formed ssDNA from nucleolytic degradation and serves as a physical platform for the recruitment of DNA damage response factors. Prominent and well-studied RPA-interacting partners are the tumor suppressor protein p53, the RAD51 recombinase and the ATR-interacting proteins ATRIP and ETAA1. RPA interactions are also documented with the helicases BLM, WRN and SMARCAL1/HARP, as well as the nucleotide excision repair proteins XPA, XPG and XPF–ERCC1. Besides its well-studied roles in DNA replication (restart) and repair, accumulating evidence shows that RPA is engaged in DNA activities in a broader biological context, including nucleosome assembly on nascent chromatin, regulation of gene expression, telomere maintenance and numerous other aspects of nucleic acid metabolism. In addition, novel RPA inhibitors show promising effects in cancer treatment, as single agents or in combination with chemotherapeutics. Since the biochemical properties of RPA and its roles in DNA repair have been extensively reviewed, here we focus on recent discoveries describing several non-canonical functions.
Collapse
Affiliation(s)
- Rositsa Dueva
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| | - George Iliakis
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, 45122 Essen, Germany
| |
Collapse
|
12
|
Nucleolin represses transcription of the androgen receptor gene through a G-quadruplex. Oncotarget 2020; 11:1758-1776. [PMID: 32477465 PMCID: PMC7233804 DOI: 10.18632/oncotarget.27589] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 04/14/2020] [Indexed: 02/03/2023] Open
Abstract
The androgen receptor (AR) is a major driver of prostate cancer development and progression. Men who develop advanced prostate cancer often have long-term cancer control when treated with androgen-deprivation therapies (ADT). Still, their disease inevitably becomes resistant to ADT and progresses to castration-resistant prostate cancer (CRPC). ADT involves potent competitive AR antagonists and androgen synthesis inhibitors. Resistance to these types of treatments emerges, primarily through the maintenance of AR signaling by ligand-independent activation mechanisms. There is a need to find better ways to block AR to overcome CRPC. In the findings reported here, we demonstrate that the nuclear scaffold protein, nucleolin (NCL), suppresses the expression of AR. NCL binds to a G-rich region in the AR promoter that forms a G-quadruplex (G4) structure. Binding of NCL to this G4-element is required for NCL to suppress AR expression, specifically in AR-expressing tumor cells. Compounds that stabilize G4 structures require NCL to associate with the G4-element of the AR promoter in order to decrease AR expression. A newly discovered G4 compound that suppresses AR expression demonstrates selective killing of AR-expressing tumor cells, including CRPC lines. Our findings raise the significant possibility that G4-stabilizing drugs can be used to increase NCL transcriptional repressor activity to block AR expression in prostate cancer. Our studies contribute to a clearer understanding of the mechanisms that control AR expression, which could be exploited to overcome CRPC.
Collapse
|
13
|
Trinh DA, Shirakawa R, Kimura T, Sakata N, Goto K, Horiuchi H. Inhibitor of Growth 4 (ING4) is a positive regulator of rRNA synthesis. Sci Rep 2019; 9:17235. [PMID: 31754246 PMCID: PMC6872537 DOI: 10.1038/s41598-019-53767-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 08/30/2019] [Indexed: 01/29/2023] Open
Abstract
Ribosome biogenesis is essential for maintaining basic cellular activities although its mechanism is not fully understood. Inhibitor of growth 4 (ING4) is a member of ING family while its cellular functions remain controversial. Here, we identified several nucleolar proteins as novel ING4 interacting proteins. ING4 localized in the nucleus with strong accumulation in the nucleolus through its plant homeodomain, which is known to interact with histone trimethylated H3K4, commonly present in the promoter of active genes. ING4 deficient cells exhibited slower proliferation and the alteration in nucleolar structure with reduced rRNA transcription, which was rescued by exogenous expression of GFP-ING4 to the similar levels of wild type cells. In the ING4 deficient cells, histone H3K9 acetylation and the key rRNA transcription factor UBF at the promoter of rDNA were reduced, both of which were also recovered by exogenous GFP-ING4 expression. Thus, ING4 could positively regulate rRNA transcription through modulation of histone modifications at the rDNA promoter.
Collapse
Affiliation(s)
- Duc-Anh Trinh
- Department of Oral Cancer Therapeutics, Graduate School of Dentistry, Tohoku University, Sendai, Japan.,Department of Molecular and Cellular Biology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Ryutaro Shirakawa
- Department of Molecular and Cellular Biology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Tomohiro Kimura
- Department of Molecular and Cellular Biology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.,Research Center for Molecular Genetics, Institute for Promotion of Medical Science Research, Yamagata University Faculty of Medicine, Yamagata, Yamagata, Japan
| | - Natsumi Sakata
- Department of Molecular and Cellular Biology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Kota Goto
- Department of Molecular and Cellular Biology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan
| | - Hisanori Horiuchi
- Department of Oral Cancer Therapeutics, Graduate School of Dentistry, Tohoku University, Sendai, Japan. .,Department of Molecular and Cellular Biology, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
| |
Collapse
|
14
|
Kawamura K, Qi F, Meng Q, Hayashi I, Kobayashi J. Nucleolar protein nucleolin functions in replication stress-induced DNA damage responses. JOURNAL OF RADIATION RESEARCH 2019; 60:281-288. [PMID: 30839063 PMCID: PMC6530621 DOI: 10.1093/jrr/rry114] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/23/2018] [Indexed: 05/05/2023]
Abstract
The nucleolus contains multiple copies of ribosomal (r)DNA, which indicate sites of frequent replication stress and suggest the existence of a mechanism to prevent replication stress-related rDNA instability and the possibility that such a mechanism contributes to the whole genomic stability against replication stress. We have previously reported that nucleolin, a major nucleolar protein, is involved in ionizing radiation-induced DNA damage responses (DDRs) such as ataxia telangiectasia mutated (ATM)-dependent cell cycle checkpoints and homologous recombination (HR) repair. Here, we investigated the role of nucleolin in DDR due to replication stress. The results indicate that following replication stress, nucleolin interacted with the histone γH2AX, proliferating cell nuclear antigen (PCNA), and replication protein A (RPA)32, suggesting that it may be recruited to DNA damage sites on the replication fork. Furthermore, the knockdown of nucleolin by siRNA reduced the activation of ATM and RAD3-related (ATR) kinase and the formation of RAD51 and RPA32 foci after replication stress due to UV or camptothecin exposure, whereas nucleolin overexpression augmented ATR-dependent phosphorylation and RAD51 and RPA accumulation on chromatin. Moreover, these overexpressing cells seemed to increase repair activity and resistance to replication stress. Our results indicate that nucleolin plays an important role in replication stress-induced DDRs such as ATR activation and HR repair. Given that nucleolin overexpression is often observed in many types of cancer cells, our findings suggest that nucleolin is involved in the regulation of resistance to replication stress that may otherwise lead to tumorigenesis and it could be a possible target for chemotherapy and radiotherapy.
Collapse
Affiliation(s)
- Kasumi Kawamura
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
| | - Fei Qi
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
| | - Qingmei Meng
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
| | - Ikue Hayashi
- Graduate School of Biomedical Sciences, Hiroshima University, Kasumi1-2-3, Minamiku, Hiroshima, Japan
| | - Junya Kobayashi
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Sciences, Kyoto University, Yoshidanihonmatsucho, Sakyo-ku, Kyoto, Japan
- Department of Genome Repair Dynamics, Radiation Biology Center, Graduate School of Biostudies, Kyoto University, Yoshidakonoecho, Sakyo-ku, Kyoto, Japan
| |
Collapse
|
15
|
Zhang X, Xiao S, Rameau RD, Devany E, Nadeem Z, Caglar E, Ng K, Kleiman FE, Saxena A. Nucleolin phosphorylation regulates PARN deadenylase activity during cellular stress response. RNA Biol 2018; 15:251-260. [PMID: 29168431 PMCID: PMC5798948 DOI: 10.1080/15476286.2017.1408764] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/11/2017] [Accepted: 11/16/2017] [Indexed: 01/28/2023] Open
Abstract
Nucleolin (NCL) is an abundant stress-responsive, RNA-binding phosphoprotein that controls gene expression by regulating either mRNA stability and/or translation. NCL binds to the AU-rich element (ARE) in the 3'UTR of target mRNAs, mediates miRNA functions in the nearby target sequences, and regulates mRNA deadenylation. However, the mechanism by which NCL phosphorylation affects these functions and the identity of the deadenylase involved, remain largely unexplored. Earlier we demonstrated that NCL phosphorylation is vital for cell cycle progression and proliferation, whereas phosphorylation-deficient NCL at six consensus CK2 sites confers dominant-negative effect on proliferation by increasing p53 expression, possibly mimicking cellular DNA damage conditions. In this study, we show that NCL phosphorylation at those CK2 consensus sites in the N-terminus is necessary to induce deadenylation upon oncogenic stimuli and UV stress. NCL-WT, but not hypophosphorylated NCL-6/S*A, activates poly (A)-specific ribonuclease (PARN) deadenylase activity. We further demonstrate that NCL interacts directly with PARN, and under non-stress conditions also forms (a) complex (es) with factors that regulate deadenylation, such as p53 and the ARE-binding protein HuR. Upon UV stress, the interaction of hypophosphorylated NCL-6/S*A with these proteins is favored. As an RNA-binding protein, NCL interacts with PARN deadenylase substrates such as TP53 and BCL2 mRNAs, playing a role in their downregulation under non-stress conditions. For the first time, we show that NCL phosphorylation offers specificity to its protein-protein, protein-RNA interactions, resulting in the PARN deadenylase regulation, and hence gene expression, during cellular stress responses.
Collapse
Affiliation(s)
- Xiaokan Zhang
- Chemistry Department, Hunter College, New York, NY, USA
| | - Shu Xiao
- Biology Department, Brooklyn College, Brooklyn, NY, USA
| | | | - Emral Devany
- Chemistry Department, Hunter College, New York, NY, USA
| | - Zaineb Nadeem
- Biology Department, Brooklyn College, Brooklyn, NY, USA
| | - Elif Caglar
- Biology Department, Brooklyn College, Brooklyn, NY, USA
| | - Kenneth Ng
- Biology Department, Brooklyn College, Brooklyn, NY, USA
| | | | - Anjana Saxena
- Biology Department, Brooklyn College, Brooklyn, NY, USA
| |
Collapse
|
16
|
Ugrinova I, Petrova M, Chalabi-Dchar M, Bouvet P. Multifaceted Nucleolin Protein and Its Molecular Partners in Oncogenesis. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 111:133-164. [PMID: 29459030 DOI: 10.1016/bs.apcsb.2017.08.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Discovered in 1973, nucleolin is one of the most abundant phosphoproteins of the nucleolus. The ability of nucleolin to be involved in many cellular processes is probably related to its structural organization and its capability to form many different interactions with other proteins. Many functions of nucleolin affect cellular processes involved in oncogenesis-for instance: in ribosome biogenesis; in DNA repair, remodeling, and genome stability; in cell division and cell survival; in chemokine and growth factor signaling pathways; in angiogenesis and lymphangiogenesis; in epithelial-mesenchymal transition; and in stemness. In this review, we will describe the different functions of nucleolin in oncogenesis through its interaction with other proteins.
Collapse
Affiliation(s)
- Iva Ugrinova
- "Roumen Tsanev" Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
| | - Maria Petrova
- "Roumen Tsanev" Institute of Molecular Biology, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Mounira Chalabi-Dchar
- Université de Lyon, Centre de Recherche en Cancérologie de Lyon, Centre Léon Bérard, Lyon, France
| | - Philippe Bouvet
- Université de Lyon, Ecole Normale Supérieure de Lyon, Lyon, France
| |
Collapse
|
17
|
Jia W, Yao Z, Zhao J, Guan Q, Gao L. New perspectives of physiological and pathological functions of nucleolin (NCL). Life Sci 2017; 186:1-10. [PMID: 28751161 DOI: 10.1016/j.lfs.2017.07.025] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/21/2017] [Accepted: 07/23/2017] [Indexed: 12/13/2022]
Abstract
Nucleolin (NCL) is a multifunctional protein that mainly localized in the nucleolus, it is also found in the nucleoplasm, cytoplasm and cell membrane. The three main structural domains allow the interaction of NCL with different proteins and RNA sequences. Moreover, specific post-translational modifications and its shuttling property also contribute to its multifunctionality. NCL has been demonstrated to be involved in a variety of aspects such as ribosome biogenesis, chromatin organization and stability, DNA and RNA metabolism, cytokinesis, cell proliferation, angiogenesis, apoptosis regulation, stress response and microRNA processing. NCL has been increasingly implicated in several pathological processes, especially in tumorigenesis and viral infection, which makes NCL a potential target for the development of anti-tumor and anti-viral strategies. In this review, we present an overview on the structure, localizations and various functions of NCL, and further describe how the multiple functions of NCL are correlated to its multiple cellular distributions.
Collapse
Affiliation(s)
- Wenyu Jia
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Zhenyu Yao
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Jiajun Zhao
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Qingbo Guan
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China
| | - Ling Gao
- Department of Endocrinology, Shandong Provincial Hospital affiliated to Shandong University, Jinan, Shandong Province, PR China; Shandong Provincial Key Laboratory of Endocrinology and Lipid Metabolism, Jinan, Shandong Province, PR China; Institute of Endocrinology and Metabolism, Shandong Academy of Clinical Medicine, Jinan, Shandong Province, PR China.
| |
Collapse
|
18
|
Bates PJ, Reyes-Reyes EM, Malik MT, Murphy EM, O'Toole MG, Trent JO. G-quadruplex oligonucleotide AS1411 as a cancer-targeting agent: Uses and mechanisms. Biochim Biophys Acta Gen Subj 2017; 1861:1414-1428. [PMID: 28007579 DOI: 10.1016/j.bbagen.2016.12.015] [Citation(s) in RCA: 201] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 12/16/2016] [Accepted: 12/17/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND AS1411 is a 26-mer G-rich DNA oligonucleotide that forms a variety of G-quadruplex structures. It was identified based on its cancer-selective antiproliferative activity and subsequently determined to be an aptamer to nucleolin, a multifunctional protein that preferentially binds quadruplex nucleic acids and which is present at high levels on the surface of cancer cells. AS1411 has exceptionally efficient cellular internalization compared to non-quadruplex DNA sequences. SCOPE OF REVIEW Recent developments related to AS1411 will be examined, with a focus on its use for targeted delivery of therapeutic and imaging agents. MAJOR CONCLUSIONS Numerous research groups have used AS1411 as a targeting agent to deliver nanoparticles, oligonucleotides, and small molecules into cancer cells. Studies in animal models have demonstrated that AS1411-linked materials can accumulate selectively in tumors following systemic administration. The mechanism underlying the cancer-targeting ability of AS1411 is not completely understood, but recent studies suggest a model that involves: (1) initial uptake by macropinocytosis, a form of endocytosis prevalent in cancer cells; (2) stimulation of macropinocytosis by a nucleolin-dependent mechanism resulting in further uptake; and (3) disruption of nucleolin-mediated trafficking and efflux leading to cargoes becoming trapped inside cancer cells. SIGNIFICANCE Human trials have indicated that AS1411 is safe and can induce durable remissions in a few patients, but new strategies are needed to maximize its clinical impact. A better understanding of the mechanisms by which AS1411 targets and kills cancer cells may hasten the development of promising technologies using AS1411-linked nanoparticles or conjugates for cancer-targeted therapy and imaging. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
Collapse
Affiliation(s)
- Paula J Bates
- Department of Medicine, University of Louisville, USA; James Graham Brown Cancer Center, University of Louisville, USA.
| | | | - Mohammad T Malik
- Department of Medicine, University of Louisville, USA; James Graham Brown Cancer Center, University of Louisville, USA
| | - Emily M Murphy
- Department of Biomedical Engineering, University of Louisville, USA
| | - Martin G O'Toole
- Department of Biomedical Engineering, University of Louisville, USA
| | - John O Trent
- Department of Medicine, University of Louisville, USA; James Graham Brown Cancer Center, University of Louisville, USA
| |
Collapse
|
19
|
Shen Y, Liu S, Fan J, Jin Y, Tian B, Zheng X, Fu H. Nuclear retention of the lncRNA SNHG1 by doxorubicin attenuates hnRNPC-p53 protein interactions. EMBO Rep 2017; 18:536-548. [PMID: 28264987 DOI: 10.15252/embr.201643139] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 01/26/2017] [Accepted: 02/06/2017] [Indexed: 01/08/2023] Open
Abstract
The protein p53 plays a crucial role in the regulation of cellular responses to diverse stresses. Thus, a major priority in cell biology is to define the mechanisms that regulate p53 activity in response to stresses or maintain it at basal levels under normal conditions. Moreover, further investigation is required to establish whether RNA participates in regulating p53's interaction with other proteins. Here, by conducting systematic experiments, we discovered a p53 interactor-hnRNPC-that directly binds to p53, destabilizes it, and prevents its activation under normal conditions. Upon doxorubicin treatment, the lncRNA SNHG1 is retained in the nucleus through its binding with nucleolin and it competes with p53 for hnRNPC binding, which upregulates p53 levels and promotes p53-dependent apoptosis by impairing hnRNPC regulation of p53 activity. Our results indicate that a balance between lncRNA SNHG1 and hnRNPC regulates p53 activity and p53-dependent apoptosis upon doxorubicin treatment, and further indicate that a change in lncRNA subcellular localization under specific circumstances is biologically significant.
Collapse
Affiliation(s)
- Yuan Shen
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China.,Department of Advanced Interdisciplinary Studies, Institute of Basic Medical Sciences and Tissue Engineering Research Center, Beijing Institute of Basic Medical Sciences, Beijing, China
| | - Shanshan Liu
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China.,Key Laboratory for Molecular Enzymology and Engineering (The Ministry of Education), College of Life Sciences, Jilin University, Changchun, Jilin, China
| | - Jiao Fan
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China.,Institute of Geriatrics, Chinese PLA General Hospital, Beijing, China
| | - Yinghua Jin
- Key Laboratory for Molecular Enzymology and Engineering (The Ministry of Education), College of Life Sciences, Jilin University, Changchun, Jilin, China
| | - Baolei Tian
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Xiaofei Zheng
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Hanjiang Fu
- Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| |
Collapse
|
20
|
Scott DD, Oeffinger M. Nucleolin and nucleophosmin: nucleolar proteins with multiple functions in DNA repair. Biochem Cell Biol 2016; 94:419-432. [PMID: 27673355 DOI: 10.1139/bcb-2016-0068] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The nucleolus represents a highly multifunctional intranuclear organelle in which, in addition to the canonical ribosome assembly, numerous processes such as transcription, DNA repair and replication, the cell cycle, and apoptosis are coordinated. The nucleolus is further a key hub in the sensing of cellular stress and undergoes major structural and compositional changes in response to cellular perturbations. Numerous nucleolar proteins have been identified that, upon sensing nucleolar stress, deploy additional, non-ribosomal roles in the regulation of varied cell processes including cell cycle arrest, arrest of DNA replication, induction of DNA repair, and apoptosis, among others. The highly abundant proteins nucleophosmin (NPM1) and nucleolin (NCL) are two such factors that transit to the nucleoplasm in response to stress, and participate directly in the repair of numerous different DNA damages. This review discusses the contributions made by NCL and (or) NPM1 to the different DNA repair pathways employed by mammalian cells to repair DNA insults, and examines the implications of such activities for the regulation, pathogenesis, and therapeutic targeting of NPM1 and NCL.
Collapse
Affiliation(s)
- Daniel D Scott
- a Laboratory of RNP Biochemistry, Institut de recherches cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
- b Division of Experimental Medicine, Faculty of Medicine, McGill University, Montréal, QC H3A 2A3, Canada
| | - Marlene Oeffinger
- a Laboratory of RNP Biochemistry, Institut de recherches cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
- b Division of Experimental Medicine, Faculty of Medicine, McGill University, Montréal, QC H3A 2A3, Canada
- c Département de biochimie et médecine moléculaire, Faculté de Médecine, Université de Montréal, QC H3T 1J4, Canada
| |
Collapse
|
21
|
The relationship between the nucleolus and cancer: Current evidence and emerging paradigms. Semin Cancer Biol 2015; 37-38:36-50. [PMID: 26721423 DOI: 10.1016/j.semcancer.2015.12.004] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/15/2015] [Accepted: 12/19/2015] [Indexed: 12/13/2022]
Abstract
The nucleolus is the most prominent nuclear substructure assigned to produce ribosomes; molecular machines that are responsible for carrying out protein synthesis. To meet the increased demand for proteins during cell growth and proliferation the cell must increase protein synthetic capacity by upregulating ribosome biogenesis. While larger nucleolar size and number have been recognized as hallmark features of many tumor types, recent evidence has suggested that, in addition to overproduction of ribosomes, decreased ribosome biogenesis as well as qualitative changes in this process could also contribute to tumor initiation and cancer progression. Furthermore, the nucleolus has become the focus of intense attention for its involvement in processes that are clearly unrelated to ribosome biogenesis such as sensing and responding to endogenous and exogenous stressors, maintenance of genome stability, regulation of cell-cycle progression, cellular senescence, telomere function, chromatin structure, establishment of nuclear architecture, global regulation of gene expression and biogenesis of multiple ribonucleoprotein particles. The fact that dysregulation of many of these fundamental cellular processes may contribute to the malignant phenotype suggests that normal functioning of the nucleolus safeguards against the development of cancer and indicates its potential as a therapeutic approach. Here we review the recent advances made toward understanding these newly-recognized nucleolar functions and their roles in normal and cancer cells, and discuss possible future research directions.
Collapse
|
22
|
Tosoni E, Frasson I, Scalabrin M, Perrone R, Butovskaya E, Nadai M, Palù G, Fabris D, Richter SN. Nucleolin stabilizes G-quadruplex structures folded by the LTR promoter and silences HIV-1 viral transcription. Nucleic Acids Res 2015; 43:8884-97. [PMID: 26354862 PMCID: PMC4605322 DOI: 10.1093/nar/gkv897] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 01/26/2023] Open
Abstract
Folding of the LTR promoter into dynamic G-quadruplex conformations has been shown to suppress its transcriptional activity in HIV-1. Here we sought to identify the proteins that control the folding of this region of proviral genome by inducing/stabilizing G-quadruplex structures. The implementation of electrophorethic mobility shift assay and pull-down experiments coupled with mass spectrometric analysis revealed that the cellular protein nucleolin is able to specifically recognize G-quadruplex structures present in the LTR promoter. Nucleolin recognized with high affinity and specificity the majority, but not all the possible G-quadruplexes folded by this sequence. In addition, it displayed greater binding preference towards DNA than RNA G-quadruplexes, thus indicating two levels of selectivity based on the sequence and nature of the target. The interaction translated into stabilization of the LTR G-quadruplexes and increased promoter silencing activity; in contrast, disruption of nucleolin binding in cells by both siRNAs and a nucleolin binding aptamer greatly increased LTR promoter activity. These data indicate that nucleolin possesses a specific and regulated activity toward the HIV-1 LTR promoter, which is mediated by G-quadruplexes. These observations provide new essential insights into viral transcription and a possible low mutagenic target for antiretroviral therapy.
Collapse
Affiliation(s)
- Elena Tosoni
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy
| | - Ilaria Frasson
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy
| | - Matteo Scalabrin
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy The RNA Institute, University at Albany-SUNY, Albany, NY 12222, USA
| | - Rosalba Perrone
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy
| | - Elena Butovskaya
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy
| | - Matteo Nadai
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy
| | - Giorgio Palù
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy
| | - Dan Fabris
- The RNA Institute, University at Albany-SUNY, Albany, NY 12222, USA
| | - Sara N Richter
- Department of Molecular Medicine, University of Padua, via Gabelli 63, 35121 Padua, Italy
| |
Collapse
|
23
|
Berger CM, Gaume X, Bouvet P. The roles of nucleolin subcellular localization in cancer. Biochimie 2015; 113:78-85. [PMID: 25866190 DOI: 10.1016/j.biochi.2015.03.023] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/29/2015] [Indexed: 01/10/2023]
Abstract
Nucleolin (NCL) is one of the most abundant non ribosomal protein of the nucleolus where it plays a central role in polymerase I transcription. NCL is also found outside of the nucleolus, in the nucleoplasm, cytoplasm as well as on the cell membrane. It acts in all cell compartments to control cellular homeostasis and therefore each cellular pool of NCL can play a different role in cancer development. NCL overexpression and its increased localization at the cell membrane is a common feature of several tumor cells. In cancer cells, NCL overexpression influences cell survival, proliferation and invasion through its action on different cellular pathways. In this review, we describe how the multiple functions of NCL that are associated to its multiple cellular localization can participate to the development of cancer.
Collapse
Affiliation(s)
- Caroline Madeleine Berger
- Département de Biologie, Master Biosciences, ENS de Lyon, Lyon, France; Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France
| | - Xavier Gaume
- Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France
| | - Philippe Bouvet
- Ecole Normale Supérieure de Lyon, Laboratoire Joliot-Curie, CNRS USR 3010, 46 allée d'Italie, 69364 Lyon Cedex 7, France.
| |
Collapse
|
24
|
Xiao S, Caglar E, Maldonado P, Das D, Nadeem Z, Chi A, Trinité B, Li X, Saxena A. Induced expression of nucleolin phosphorylation-deficient mutant confers dominant-negative effect on cell proliferation. PLoS One 2014; 9:e109858. [PMID: 25313645 PMCID: PMC4196967 DOI: 10.1371/journal.pone.0109858] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 09/08/2014] [Indexed: 11/25/2022] Open
Abstract
Nucleolin (NCL) is a major nucleolar phosphoprotein that has pleiotropic effects on cell proliferation and is elevated in a variety of tumors. NCL is highly phosphorylated at the N-terminus by two major kinases: interphase casein kinase 2 (CK2) and mitotic cyclin-dependent kinase 1 (CDK1). Earlier we demonstrated that a NCL-mutant that is partly defective in undergoing phosphorylation by CK2 inhibits chromosomal replication through its interactions with Replication Protein A, mimicking the cellular response to DNA damage. We further delineated that the N-terminus of NCL associates with Hdm2, the most common E3 ubiquitin ligase of p53. We reported that NCL antagonizes Hdm2 to stabilize p53 and stimulates p53 transcriptional activity. Although NCL-phosphorylation by CK2 and ribosomal DNA transcription are closely coordinated during interphase, the role of NCL phosphorylation in regulating cell proliferation remains unexplored. We have therefore engineered unique human cells that specifically induce expression of NCL-wild type (WT) or a phosphorylation-deficient NCL-mutant, 6/S*A where all the six CK2 consensus serine sites residing in the N-terminus NCL were mutated to alanine. Here we show that this NCL-mutant is defective in undergoing phosphorylation by CK2. We also demonstrate that NCL-phosphorylation by CK2 is required through the S-phase progression in cell cycle and hence proliferation. Induced expression of NCL with mutated CK2 phosphorylation sites stabilizes p53, results in higher expression of Bcl2 (B-cell lymphoma 2) homology 3 (BH3)-only apoptotic markers and causes a dominant-negative effect on cell viability. Our unique cellular system thus provides the first evidential support to delineate phospho-specific functions of NCL on cell proliferation.
Collapse
Affiliation(s)
- Shu Xiao
- Biology Department, Brooklyn College, Brooklyn, New York, United States of America
- City University of New York, Graduate Center, New York, New York, United States of America
| | - Elif Caglar
- Biology Department, Brooklyn College, Brooklyn, New York, United States of America
| | - Priscilla Maldonado
- New York University School of Medicine, New York, New York, United States of America
| | - Dibash Das
- Biology Department, Brooklyn College, Brooklyn, New York, United States of America
- City University of New York, Graduate Center, New York, New York, United States of America
| | - Zaineb Nadeem
- Biology Department, Brooklyn College, Brooklyn, New York, United States of America
| | - Angela Chi
- Great Neck South High School, Great Neck, New York, United States of America
| | - Benjamin Trinité
- New York University College of Dentistry, New York, New York, United States of America
| | - Xin Li
- New York University College of Dentistry, New York, New York, United States of America
| | - Anjana Saxena
- Biology Department, Brooklyn College, Brooklyn, New York, United States of America
- City University of New York, Graduate Center, New York, New York, United States of America
| |
Collapse
|
25
|
Allinne J, Pichugin A, Iarovaia O, Klibi M, Barat A, Zlotek-Zlotkiewicz E, Markozashvili D, Petrova N, Camara-Clayette V, Ioudinkova E, Wiels J, Razin SV, Ribrag V, Lipinski M, Vassetzky YS. Perinucleolar relocalization and nucleolin as crucial events in the transcriptional activation of key genes in mantle cell lymphoma. Blood 2014; 123:2044-53. [PMID: 24452204 DOI: 10.1182/blood-2013-06-510511] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In mantle cell lymphoma (MCL), one allele of the cyclin D1 (Ccnd1) gene is translocated from its normal localization on chromosome 11 to chromosome 14. This is considered as the crucial event in the transformation process of a normal naive B-cell; however, the actual molecular mechanism leading to Ccnd1 activation remains to be deciphered. Using a combination of three-dimensional and immuno-fluorescence in situ hybridization experiments, the radial position of the 2 Ccnd1 alleles was investigated in MCL-derived cell lines and malignant cells from affected patients. The translocated Ccnd1 allele was observed significantly more distant from the nuclear membrane than its nontranslocated counterpart, with a very high proportion of IgH-Ccnd1 chromosomal segments localized next to a nucleolus. These perinucleolar areas were found to contain active RNA polymerase II (PolII) clusters. Nucleoli are rich in nucleolin, a potent transcription factor that we found to bind sites within the Ccnd1 gene specifically in MCL cells and to activate Ccnd1 transcription. We propose that the Ccnd1 transcriptional activation in MCL cells relates to the repositioning of the rearranged IgH-Ccnd1-carrying chromosomal segment in a nuclear territory with abundant nucleolin and active PolII molecules. Similar transforming events could occur in Burkitt and other B-cell lymphomas.
Collapse
Affiliation(s)
- Jeanne Allinne
- Unité Mixte de Recherche 8126, Université Paris-Sud, National Centre for Scientific Research, Institut de Cancérologie Gustave Roussy, Villejuif, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Atwood SE, O'Rourke JA, Peiffer GA, Yin T, Majumder M, Zhang C, Cianzio SR, Hill JH, Cook D, Whitham SA, Shoemaker RC, Graham MA. Replication protein A subunit 3 and the iron efficiency response in soybean. PLANT, CELL & ENVIRONMENT 2014; 37:213-34. [PMID: 23742135 DOI: 10.1111/pce.12147] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/09/2013] [Accepted: 05/28/2013] [Indexed: 05/20/2023]
Abstract
In soybean [Glycine max (L.) Merr.], iron deficiency results in interveinal chlorosis and decreased photosynthetic capacity, leading to stunting and yield loss. In this study, gene expression analyses investigated the role of soybean replication protein A (RPA) subunits during iron stress. Nine RPA homologs were significantly differentially expressed in response to iron stress in the near isogenic lines (NILs) Clark (iron efficient) and Isoclark (iron inefficient). RPA homologs exhibited opposing expression patterns in the two NILs, with RPA expression significantly repressed during iron deficiency in Clark but induced in Isoclark. We used virus induced gene silencing (VIGS) to repress GmRPA3 expression in the iron inefficient line Isoclark and mirror expression in Clark. GmRPA3-silenced plants had improved IDC symptoms and chlorophyll content under iron deficient conditions and also displayed stunted growth regardless of iron availability. RNA-Seq comparing gene expression between GmRPA3-silenced and empty vector plants revealed massive transcriptional reprogramming with differential expression of genes associated with defense, immunity, aging, death, protein modification, protein synthesis, photosynthesis and iron uptake and transport genes. Our findings suggest the iron efficient genotype Clark is able to induce energy controlling pathways, possibly regulated by SnRK1/TOR, to promote nutrient recycling and stress responses in iron deficient conditions.
Collapse
Affiliation(s)
- Sarah E Atwood
- Interdepartmental Genetics Program, Iowa State University, Ames, IA, 50011, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Mulvey CM, Tudzarova S, Crawford M, Williams GH, Stoeber K, Godovac-Zimmermann J. Subcellular proteomics reveals a role for nucleo-cytoplasmic trafficking at the DNA replication origin activation checkpoint. J Proteome Res 2013; 12:1436-53. [PMID: 23320540 PMCID: PMC4261602 DOI: 10.1021/pr3010919] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Depletion of DNA replication initiation factors such as CDC7 kinase triggers the origin activation checkpoint in healthy cells and leads to a protective cell cycle arrest at the G1 phase of the mitotic cell division cycle. This protective mechanism is thought to be defective in cancer cells. To investigate how this checkpoint is activated and maintained in healthy cells, we conducted a quantitative SILAC analysis of the nuclear- and cytoplasmic-enriched compartments of CDC7-depleted fibroblasts and compared them to a total cell lysate preparation. Substantial changes in total abundance and/or subcellular location were detected for 124 proteins, including many essential proteins associated with DNA replication/cell cycle. Similar changes in protein abundance and subcellular distribution were observed for various metabolic processes, including oxidative stress, iron metabolism, protein translation and the tricarboxylic acid cycle. This is accompanied by reduced abundance of two karyopherin proteins, suggestive of reduced nuclear import. We propose that altered nucleo-cytoplasmic trafficking plays a key role in the regulation of cell cycle arrest. The results increase understanding of the mechanisms underlying maintenance of the DNA replication origin activation checkpoint and are consistent with our proposal that cell cycle arrest is an actively maintained process that appears to be distributed over various subcellular locations.
Collapse
Affiliation(s)
- Claire M. Mulvey
- Division of Medicine, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom
| | - Slavica Tudzarova
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Mark Crawford
- Division of Medicine, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom
| | - Gareth H. Williams
- Research Department of Pathology and UCL Cancer Institute, Rockefeller Building, University College London, University Street, London WC1E 6JJ, United Kingdom
| | - Kai Stoeber
- Research Department of Pathology and UCL Cancer Institute, Rockefeller Building, University College London, University Street, London WC1E 6JJ, United Kingdom
| | - Jasminka Godovac-Zimmermann
- Division of Medicine, University College London, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom
| |
Collapse
|
28
|
Wei PC, Wang ZF, Lo WT, Su MI, Shew JY, Chang TC, Lee WH. A cis-element with mixed G-quadruplex structure of NPGPx promoter is essential for nucleolin-mediated transactivation on non-targeting siRNA stress. Nucleic Acids Res 2013; 41:1533-43. [PMID: 23241391 PMCID: PMC3561993 DOI: 10.1093/nar/gks1232] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 10/31/2012] [Accepted: 10/31/2012] [Indexed: 12/16/2022] Open
Abstract
We reported that non-targeting siRNA (NT-siRNA) stress induces non-selenocysteine containing phospholipid hydroperoxide glutathione peroxidase (NPGPx) expression to cooperate with exoribonuclease XRN2 for releasing the stress [Wei,P.C., Lo,W.T., Su,M.I., Shew,J.Y. and Lee,W.H. (2011) Non-targeting siRNA induces NPGPx expression to cooperate with exoribonuclease XRN2 for releasing the stress. Nucleic Acids Res., 40, 323-332]. However, how NT-siRNA stress inducing NPGPx expression remains elusive. In this communication, we showed that the proximal promoter of NPGPx contained a mixed G-quadruplex (G4) structure, and disrupting the structure diminished NT-siRNA induced NPGPx promoter activity. We also demonstrated that nucleolin (NCL) specifically bonded to the G4-containing sequences to replace the originally bound Sp1 at the NPGPx promoter on NT-siRNA stress. Consistently, overexpression of NCL further increased NPGPx promoter activity, whereas depletion of NCL desensitized NPGPx promoter to NT-siRNA stress. These results suggest that the cis-element with mixed G4 structure at the NPGPx promoter plays an essential role for its transactivation mediated by NCL to release cells from NT-siRNA stress.
Collapse
Affiliation(s)
- Pei-Chi Wei
- Graduate Institute of Life Sciences, National Defense Medical Center, 11490 Taipei, Taiwan, Genomics Research Center, 11529 Taipei, Institute of Atomic and Molecular Sciences, Academia Sinica, 11529 Taipei, Department of Chemistry, National Taiwan University, 11529 Taipei, Institute of Biological Chemistry, Academia Sinica, 11529 Taipei, Taiwan and Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Zi-Fu Wang
- Graduate Institute of Life Sciences, National Defense Medical Center, 11490 Taipei, Taiwan, Genomics Research Center, 11529 Taipei, Institute of Atomic and Molecular Sciences, Academia Sinica, 11529 Taipei, Department of Chemistry, National Taiwan University, 11529 Taipei, Institute of Biological Chemistry, Academia Sinica, 11529 Taipei, Taiwan and Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Wen-Ting Lo
- Graduate Institute of Life Sciences, National Defense Medical Center, 11490 Taipei, Taiwan, Genomics Research Center, 11529 Taipei, Institute of Atomic and Molecular Sciences, Academia Sinica, 11529 Taipei, Department of Chemistry, National Taiwan University, 11529 Taipei, Institute of Biological Chemistry, Academia Sinica, 11529 Taipei, Taiwan and Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Mei-I Su
- Graduate Institute of Life Sciences, National Defense Medical Center, 11490 Taipei, Taiwan, Genomics Research Center, 11529 Taipei, Institute of Atomic and Molecular Sciences, Academia Sinica, 11529 Taipei, Department of Chemistry, National Taiwan University, 11529 Taipei, Institute of Biological Chemistry, Academia Sinica, 11529 Taipei, Taiwan and Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Jin-Yuh Shew
- Graduate Institute of Life Sciences, National Defense Medical Center, 11490 Taipei, Taiwan, Genomics Research Center, 11529 Taipei, Institute of Atomic and Molecular Sciences, Academia Sinica, 11529 Taipei, Department of Chemistry, National Taiwan University, 11529 Taipei, Institute of Biological Chemistry, Academia Sinica, 11529 Taipei, Taiwan and Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Ta-Chau Chang
- Graduate Institute of Life Sciences, National Defense Medical Center, 11490 Taipei, Taiwan, Genomics Research Center, 11529 Taipei, Institute of Atomic and Molecular Sciences, Academia Sinica, 11529 Taipei, Department of Chemistry, National Taiwan University, 11529 Taipei, Institute of Biological Chemistry, Academia Sinica, 11529 Taipei, Taiwan and Department of Biological Chemistry, University of California, Irvine, California, USA
| | - Wen-Hwa Lee
- Graduate Institute of Life Sciences, National Defense Medical Center, 11490 Taipei, Taiwan, Genomics Research Center, 11529 Taipei, Institute of Atomic and Molecular Sciences, Academia Sinica, 11529 Taipei, Department of Chemistry, National Taiwan University, 11529 Taipei, Institute of Biological Chemistry, Academia Sinica, 11529 Taipei, Taiwan and Department of Biological Chemistry, University of California, Irvine, California, USA
| |
Collapse
|
29
|
Kobayashi J, Fujimoto H, Sato J, Hayashi I, Burma S, Matsuura S, Chen DJ, Komatsu K. Nucleolin participates in DNA double-strand break-induced damage response through MDC1-dependent pathway. PLoS One 2012; 7:e49245. [PMID: 23145133 PMCID: PMC3492271 DOI: 10.1371/journal.pone.0049245] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Accepted: 10/05/2012] [Indexed: 01/05/2023] Open
Abstract
H2AX is an important factor for chromatin remodeling to facilitate accumulation of DNA damage-related proteins at DNA double-strand break (DSB) sites. In order to further understand the role of H2AX in the DNA damage response (DDR), we attempted to identify H2AX-interacting proteins by proteomics analysis. As a result, we identified nucleolin as one of candidates. Here, we show a novel role of a major nucleolar protein, nucleolin, in DDR. Nucleolin interacted with γ-H2AX and accumulated to laser micro-irradiated DSB damage sites. Chromatin Immunoprecipitation assay also displayed the accumulation of nucleolin around DSB sites. Nucleolin-depleted cells exhibited repression of both ATM-dependent phosphorylation following exposure to γ-ray and subsequent cell cycle checkpoint activation. Furthermore, nucleolin-knockdown reduced HR and NHEJ activity and showed decrease in IR-induced chromatin accumulation of HR/NHEJ factors, agreeing with the delayed kinetics of γ-H2AX focus. Moreover, nucleolin-knockdown decreased MDC1-related events such as focus formation of 53 BP1, RNF168, phosphorylated ATM, and H2A ubiquitination. Nucleolin also showed FACT-like activity for DSB damage-induced histone eviction from chromatin. Taken together, nucleolin could promote both ATM-dependent cell cycle checkpoint and DSB repair by functioning in an MDC1-related pathway through its FACT-like function.
Collapse
Affiliation(s)
- Junya Kobayashi
- Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Indig FE, Rybanska I, Karmakar P, Devulapalli C, Fu H, Carrier F, Bohr VA. Nucleolin inhibits G4 oligonucleotide unwinding by Werner helicase. PLoS One 2012; 7:e35229. [PMID: 22675465 PMCID: PMC3366963 DOI: 10.1371/journal.pone.0035229] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 03/14/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The Werner protein (WRNp), a member of the RecQ helicase family, is strongly associated with the nucleolus, as is nucleolin (NCL), an important nucleolar constituent protein. Both WRNp and NCL respond to the effects of DNA damaging agents. Therefore, we have investigated if these nuclear proteins interact and if this interaction has a possible functional significance in DNA damage repair. METHODOLOGY/PRINCIPAL FINDINGS Here we report that WRNp interacts with the RNA-binding protein, NCL, based on immunoprecipitation, immunofluorescent co-localization in live and fixed cells, and direct binding of purified WRNp to nucleolin. We also map the binding region to the C-terminal domains of both proteins. Furthermore, treatment of U2OS cells with 15 µM of the Topoisomerase I inhibitor, camptothecin, causes the dissociation of the nucleolin-Werner complex in the nucleolus, followed by partial re-association in the nucleoplasm. Other DNA damaging agents, such as hydroxyurea, Mitomycin C, and aphidicolin do not have these effects. Nucleolin or its C-terminal fragment affected the helicase, but not the exonuclease activity of WRNp, by inhibiting WRN unwinding of G4 tetraplex DNA structures, as seen in activity assays and electrophoretic mobility shift assays (EMSA). CONCLUSIONS/SIGNIFICANCE These data suggest that nucleolin may regulate G4 DNA unwinding by WRNp, possibly in response to certain DNA damaging agents. We postulate that the NCL-WRNp complex may contain an inactive form of WRNp, which is released from the nucleolus upon DNA damage. Then, when required, WRNp is released from inhibition and can participate in the DNA repair processes.
Collapse
Affiliation(s)
- Fred E Indig
- Laboratory of Clinical Investigation, Intramural Research Program, National Institute on Aging, National Institutes of Health, Department of Health and Human Services, Baltimore, Maryland, United States of America.
| | | | | | | | | | | | | |
Collapse
|
31
|
Bhatt P, d’Avout C, Kane NS, Borowiec JA, Saxena A. Specific domains of nucleolin interact with Hdm2 and antagonize Hdm2-mediated p53 ubiquitination. FEBS J 2012; 279:370-83. [PMID: 22103682 PMCID: PMC3262062 DOI: 10.1111/j.1742-4658.2011.08430.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Nucleolin is an abundant multifunctional nucleolar protein with defined roles in ribosomal RNA processing, RNA polymerase I catalyzed transcription and the regulation of apoptosis. Earlier we reported that human nucleolin binds to the p53 antagonist human double minute 2 (Hdm2) as determined by reciprocal co-immunoprecipitation assays using cell lysates. We also demonstrated that nucleolin antagonizes Hdm2-mediated degradation of p53. Here, we identify specific domains of nucleolin and Hdm2 proteins that support mutual interaction and investigate the implications of complex formation on p53 ubiquitination and protein levels. Our data indicate that the nucleolin N-terminus as well as the central RNA-binding domain (RBD) are predominantly involved in binding to Hdm2. The nucleolin RBD robustly bound to the NLS/NES (nuclear localization and export signals) domain of Hdm2 in vitro, while the N-terminus of nucleolin preferentially associated with the Hdm2 RING (really interesting new gene) domain expressed in cells. We further demonstrate that the C-terminal glycine-arginine rich domain of nucleolin serves as the predominant binding domain for direct interaction with p53. While overexpression of nucleolin or its various domains had no significant effect on Hdm2 auto-ubiquitination, the nucleolin RBD antagonized the Hdm2 E3 ligase activity against p53, leading to p53 stabilization. Conversely, the adjacent glycine-arginine rich domain of nucleolin interacted with p53 causing a modest stimulatory effect on p53 ubiquitination. These data suggest that changes in nucleolin conformation can alter the availabilities of such domains in vivo to modulate the overall impact of nucleolin on Hdm2 activity and hence on p53 stability.
Collapse
Affiliation(s)
- Purvi Bhatt
- New York University School of Medicine, New York, NY
| | | | - Naomi S. Kane
- New York University School of Medicine, New York, NY
| | | | | |
Collapse
|
32
|
Carra C, Saha J, Cucinotta FA. Theoretical prediction of the binding free energy for mutants of replication protein A. J Mol Model 2011; 18:3035-49. [PMID: 22160652 DOI: 10.1007/s00894-011-1313-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 11/16/2011] [Indexed: 01/29/2023]
Abstract
The replication protein A (RPA) is a heterotrimeric (70, 32, and 14 kDa subunits), single stranded DNA (ssDNA) binding protein required for pivotal functions in the cell metabolism, such as chromosomal replication, prevention of hairpin formation, DNA repair and recombination, and signaling after DNA damage. Studies based on deletions and mutations have identified the high affinity ssDNA binding domains in the 70 kDa subunit of RPA, regions A and B. Individually, the domain A and B have a low affinity for ssDNA, while tandems composed of AA, AB, BB, and BA sequences bind the ssDNA with moderate to high affinity. Single and double point mutations on polar residues in the binding domains leads to a reduction in affinity of RPA for ssDNA, in particular when two hydrophilic residues are involved. In view of these results, we performed a study based on molecular dynamics simulation aimed to reproduce the experimental change in binding free energy, ΔΔG, of RPA70 mutants to further elucidate the nature of the protein-ssDNA interaction. The MM-PB(GB)SA methods implemented in Amber10 and the code FoldX were used to estimate the binding free energy. The theoretical and experimental ΔΔG values correlate better when the results are obtained by MM-PBSA calculated on individual trajectories for each mutant. In these conditions, the correlation coefficient between experimental and theoretical ΔΔG reaches a value of 0.95 despite the overestimation of the energy change by one order of magnitude. The decomposition of the MM-GBSA energy per residue allows us to correlate the change of the affinity with the residue polarity and energy contribution to the binding. The method revealed reliable predictions of the change in the affinity in function of mutations, and can be used to identify new mutants with distinct binding properties.
Collapse
Affiliation(s)
- Claudio Carra
- Universities Space Research Association, Columbia, MD, USA.
| | | | | |
Collapse
|
33
|
Carra C, Cucinotta FA. Accurate prediction of the binding free energy and analysis of the mechanism of the interaction of replication protein A (RPA) with ssDNA. J Mol Model 2011; 18:2761-83. [PMID: 22116609 DOI: 10.1007/s00894-011-1288-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 10/19/2011] [Indexed: 10/15/2022]
Abstract
The eukaryotic replication protein A (RPA) has several pivotal functions in the cell metabolism, such as chromosomal replication, prevention of hairpin formation, DNA repair and recombination, and signaling after DNA damage. Moreover, RPA seems to have a crucial role in organizing the sequential assembly of DNA processing proteins along single stranded DNA (ssDNA). The strong RPA affinity for ssDNA, K(A) between 10(-9)-10(-10) M, is characterized by a low cooperativity with minor variation for changes on the nucleotide sequence. Recently, new data on RPA interactions was reported, including the binding free energy of the complex RPA70AB with dC(8) and dC(5), which has been estimated to be -10 ± 0.4 kcal mol(-1) and -7 ± 1 kcal mol(-1), respectively. In view of these results we performed a study based on molecular dynamics aimed to reproduce the absolute binding free energy of RPA70AB with the dC(5) and dC(8) oligonucleotides. We used several tools to analyze the binding free energy, rigidity, and time evolution of the complex. The results obtained by MM-PBSA method, with the use of ligand free geometry as a reference for the receptor in the separate trajectory approach, are in excellent agreement with the experimental data, with ±4 kcal mol(-1) error. This result shows that the MM-PB(GB)SA methods can provide accurate quantitative estimates of the binding free energy for interacting complexes when appropriate geometries are used for the receptor, ligand and complex. The decomposition of the MM-GBSA energy for each residue in the receptor allowed us to correlate the change of the affinity of the mutated protein with the ΔG(gas+sol) contribution of the residue considered in the mutation. The agreement with experiment is optimal and a strong change in the binding free energy can be considered as the dominant factor in the loss for the binding affinity resulting from mutation.
Collapse
Affiliation(s)
- Claudio Carra
- Universities Space Research Association, Houston, TX 77058, USA.
| | | |
Collapse
|
34
|
Tajrishi MM, Tuteja R, Tuteja N. Nucleolin: The most abundant multifunctional phosphoprotein of nucleolus. Commun Integr Biol 2011; 4:267-75. [PMID: 21980556 DOI: 10.4161/cib.4.3.14884] [Citation(s) in RCA: 172] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 01/18/2011] [Indexed: 01/08/2023] Open
Abstract
Nucleolin is a multifunctional phosphoprotein ubiquitously distributed in the nucleolus, nucleus and cytoplasm of the cell. Nucleolin has a bipartite nuclear localization signal sequence and is conserved in animals, plants and yeast. Its levels are correlated with the rate of functional activity of the nucleolus in exponentially growing cells. Nucleolin contains intrinsic DNA and RNA helicase, nucleic-acid-dependent ATPase and self-cleaving activities. It binds RNA through its RNA recognition motifs. It regulates various aspects of DNA and RNA metabolism, chromatin structure, rDNA transcription, rRNA maturation, cytokinesis, nucleogenesis, cell proliferation and growth, the folding, maturation and ribosome assembly and nucleocytoplasmic transport of newly synthesized pre-RNAs. In this review we present an overview on nucleolin, its localization, structure and various functions. We also describe the discovery and important studies of nucleolin in plants.
Collapse
Affiliation(s)
- Marjan M Tajrishi
- International Center for Genetic Engineering and Biotechnology; Aruna Asaf Ali Marg; New Delhi, Delhi India
| | | | | |
Collapse
|
35
|
Arcangeletti MC, Rodighiero I, Mirandola P, De Conto F, Covan S, Germini D, Razin S, Dettori G, Chezzi C. Cell-cycle-dependent localization of human cytomegalovirus UL83 phosphoprotein in the nucleolus and modulation of viral gene expression in human embryo fibroblasts in vitro. J Cell Biochem 2011; 112:307-17. [PMID: 21053310 DOI: 10.1002/jcb.22928] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The nucleolus is a multifunctional nuclear compartment widely known to be involved in several cellular processes, including mRNA maturation and shuttling to cytoplasmic sites, control of the cell cycle, cell proliferation, and apoptosis; thus, it is logical that many viruses, including herpesvirus, target the nucleolus in order to exploit at least one of the above-mentioned functions. Recent studies from our group demonstrated the early accumulation of the incoming ppUL83 (pp65), the major tegument protein of human cytomegalovirus (HCMV), in the nucleolus. The obtained results also suggested that a functional relationship might exist between the nucleolar localization of pp65, rRNA synthesis, and the development of the lytic program of viral gene expression. Here we present new data which support the hypothesis of a potentially relevant role of HCMV pp65 and its nucleolar localization for the control of the cell cycle by HCMV (arrest of cell proliferation in G1-G1/S), and for the promotion of viral infection. We demonstrated that, although the incoming pp65 amount in the infected cells appears to be constant irrespective of the cell-cycle phase, its nucleolar accumulation is prominent in G1 and G1/S, but very poor in S or G2/M. This correlates with the observation that only cells in G1 and G1/S support an efficient development of the HCMV lytic cycle. We propose that HCMV pp65 might be involved in regulatory/signaling pathways related to nucleolar functions, such as the cell-cycle control. Co-immunoprecipitation experiments have permitted to identify nucleolin as one of the nucleolar partners of pp65.
Collapse
|
36
|
Abstract
G-quadruplexes are four-stranded DNA structures that are over-represented in gene promoter regions and are viewed as emerging therapeutic targets in oncology, as transcriptional repression of oncogenes through stabilization of these structures could be a novel anticancer strategy. Many gene promoter G-quadruplexes have physicochemical properties and structural characteristics that might make them druggable, and their structural diversity suggests that a high degree of selectivity might be possible. Here, we describe the evidence for G-quadruplexes in gene promoters and discuss their potential as therapeutic targets, as well as progress in the development of strategies to harness this potential through intervention with small-molecule ligands.
Collapse
|
37
|
Hovanessian AG, Soundaramourty C, El Khoury D, Nondier I, Svab J, Krust B. Surface expressed nucleolin is constantly induced in tumor cells to mediate calcium-dependent ligand internalization. PLoS One 2010; 5:e15787. [PMID: 21203423 PMCID: PMC3009748 DOI: 10.1371/journal.pone.0015787] [Citation(s) in RCA: 156] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 11/24/2010] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Nucleolin is one of the major proteins of the nucleolus, but it is also expressed on the cell surface where is serves as a binding protein for variety of ligands implicated in tumorigenesis and angiogenesis. Emerging evidence suggests that the cell-surface expressed nucleolin is a strategic target for an effective and nontoxic cancer therapy. METHODOLOGY/PRINCIPAL FINDINGS By monitoring the expression of nucleolin mRNA, and by measuring the level of nucleolin protein recovered from the surface and nucleus of cells, here we show that the presence of nucleolin at the cell surface is dependent on the constant induction of nucleolin mRNA. Indeed, inhibitors of RNA transcription or translation block expression of surface nucleolin while no apparent effect is observed on the level of nucleolin in the nucleus. The estimated half-life of surface nucleolin is less than one hour, whereas that of nuclear nucleolin is more than 8 hours. Nucleolin mRNA induction is reduced markedly in normal fibroblasts that reach confluence, while it occurs continuously even in post-confluent epithelial tumor cells consistent with their capacity to proliferate without contact inhibition. Interestingly, cold and heat shock induce nucleolin mRNA concomitantly to enhanced mRNA expression of the heat shock protein 70, thus suggesting that surface nucleolin induction also occurs in response to an environmental insult. At the cell surface, one of the main functions of nucleolin is to shuttle specific extracellular ligands by an active transport mechanism, which we show here to be calcium dependent. CONCLUSION/SIGNIFICANCE Our results demonstrate that the expression of surface nucleolin is an early metabolic event coupled with tumor cell proliferation and stress response. The fact that surface nucleolin is constantly and abundantly expressed on the surface of tumor cells, makes them a preferential target for the inhibitory action of anticancer agents that target surface nucleolin.
Collapse
Affiliation(s)
- Ara G Hovanessian
- CNRS-Université Paris Descartes, Unité Régulation de la Transcription de Maladies Génétique, Paris, France.
| | | | | | | | | | | |
Collapse
|
38
|
González V, Hurley LH. The C-terminus of nucleolin promotes the formation of the c-MYC G-quadruplex and inhibits c-MYC promoter activity. Biochemistry 2010; 49:9706-14. [PMID: 20932061 PMCID: PMC2976822 DOI: 10.1021/bi100509s] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nucleolin, the most abundant nucleolar phosphoprotein of eukaryotic cells, is known primarily for its role in ribosome biogenesis and cell proliferation. It is, however, a multifunctional protein that, depending on the cellular context, can drive either cell proliferation or apoptosis. Our laboratory recently demonstrated that nucleolin can function as a repressor of c-MYC transcription by binding to and stabilizing the formation of a G-quadruplex structure in a region of the c-MYC promoter responsible for controlling 85-90% of c-MYC's transcriptional activity. In this study, we investigate the structural elements of nucleolin that are required for c-MYC repression. The effect of nucleolin deletion mutants on the formation and stability of the c-MYC G-quadruplex, as well as c-MYC transcriptional activity, was assessed by circular dichroism spectropolarimetry, thermal stability, and in vitro transcription. Here we report that nucleolin's RNA binding domains 3 and 4, as well as the arginine-glycine-glycine (RGG) domain, are required to repress c-MYC transcription.
Collapse
Affiliation(s)
- Verónica González
- College of Pharmacy, Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona 85721
| | - Laurence H. Hurley
- College of Pharmacy, Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona 85721
- University of Arizona, BIO5 Institute, Tucson, Arizona 85721
- University of Arizona, Arizona Cancer Center, Tucson, Arizona 85724
| |
Collapse
|
39
|
Shears SB, Gokhale NA, Wang H, Zaremba A. Diphosphoinositol polyphosphates: what are the mechanisms? ACTA ACUST UNITED AC 2010; 51:13-25. [PMID: 21035493 DOI: 10.1016/j.advenzreg.2010.09.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Accepted: 09/17/2010] [Indexed: 12/30/2022]
Abstract
In countries where adulthood is considered to be attained at age eighteen, 2011 can be the point at which the diphosphoinositol polyphosphates might formally be described as "coming of age", since these molecules were first fully defined in 1993 (Menniti et al., 1993; Stephens et al., 1993b). But from a biological perspective, these polyphosphates cannot quite be considered to have matured into the status of being independently-acting intracellular signals. This review has discussed several of the published proposals for mechanisms by which the diphosphoinositol polyphosphates might act. We have argued that all of these hypotheses need further development.We also still do not know a single molecular mechanism by which a change in the levels of a particular diphosphoinositol polyphosphate can be controlled. Yet, despite all these gaps in our understanding, there is an enduring anticipation that these molecules have great potential in the signaling field. Reflecting our expectations of all teenagers, it should be our earnest hope that in the near future the diphosphoinositol polyphosphates will finally grow up.
Collapse
Affiliation(s)
- Stephen B Shears
- Inositol Signaling Group, Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
| | | | | | | |
Collapse
|
40
|
Langley AR, Chambers H, Christov CP, Krude T. Ribonucleoprotein particles containing non-coding Y RNAs, Ro60, La and nucleolin are not required for Y RNA function in DNA replication. PLoS One 2010; 5:e13673. [PMID: 21060685 PMCID: PMC2965120 DOI: 10.1371/journal.pone.0013673] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 10/06/2010] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Ro ribonucleoprotein particles (Ro RNPs) consist of a non-coding Y RNA bound by Ro60, La and possibly other proteins. The physiological function of Ro RNPs is controversial as divergent functions have been reported for its different constituents. We have recently shown that Y RNAs are essential for the initiation of mammalian chromosomal DNA replication, whereas Ro RNPs are implicated in RNA stability and RNA quality control. Therefore, we investigate here the functional consequences of RNP formation between Ro60, La and nucleolin proteins with hY RNAs for human chromosomal DNA replication. METHODOLOGY/PRINCIPAL FINDINGS We first immunoprecipitated Ro60, La and nucleolin together with associated hY RNAs from HeLa cytosolic cell extract, and analysed the protein and RNA compositions of these precipitated RNPs by Western blotting and quantitative RT-PCR. We found that Y RNAs exist in several RNP complexes. One RNP comprises Ro60, La and hY RNA, and a different RNP comprises nucleolin and hY RNA. In addition about 50% of the Y RNAs in the extract are present outside of these two RNPs. Next, we immunodepleted these RNP complexes from the cytosolic extract and tested the ability of the depleted extracts to reconstitute DNA replication in a human cell-free system. We found that depletion of these RNP complexes from the cytosolic extract does not inhibit DNA replication in vitro. Finally, we tested if an excess of recombinant pure Ro or La protein inhibits Y RNA-dependent DNA replication in this cell-free system. We found that Ro60 and La proteins do not inhibit DNA replication in vitro. CONCLUSIONS/SIGNIFICANCE We conclude that RNPs containing hY RNAs and Ro60, La or nucleolin are not required for the function of hY RNAs in chromosomal DNA replication in a human cell-free system, which can be mediated by Y RNAs outside of these RNPs. These data suggest that Y RNAs can support different cellular functions depending on associated proteins.
Collapse
Affiliation(s)
| | - Helen Chambers
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | | | - Torsten Krude
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| |
Collapse
|
41
|
Strang BL, Boulant S, Coen DM. Nucleolin associates with the human cytomegalovirus DNA polymerase accessory subunit UL44 and is necessary for efficient viral replication. J Virol 2010; 84:1771-84. [PMID: 20007282 PMCID: PMC2812382 DOI: 10.1128/jvi.01510-09] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2009] [Accepted: 11/23/2009] [Indexed: 01/04/2023] Open
Abstract
In the eukaryotic cell, DNA replication entails the interaction of multiple proteins with the DNA polymerase processivity factor PCNA. As the structure of the presumptive human cytomegalovirus (HCMV) DNA polymerase processivity factor UL44 is highly homologous to that of PCNA, we hypothesized that UL44 also interacts with numerous proteins. To investigate this possibility, recombinant HCMV expressing FLAG-tagged UL44 was generated and used to immunoprecipitate UL44 and associated proteins from infected cell lysates. Unexpectedly, nucleolin, a major protein component of the nucleolus, was identified among these proteins by mass spectrometry and Western blotting. The association of nucleolin and UL44 in infected cell lysate was confirmed by reciprocal coimmunoprecipitation in the presence and absence of nuclease. Western blotting and immunofluorescence assays demonstrated that the level of nucleolin increases during infection and that nucleolin becomes distributed throughout the nucleus. Furthermore, the colocalization of nucleolin and UL44 in infected cell nuclei was observed by immunofluorescence assays. Assays of HCMV-infected cells treated with small interfering RNA (siRNA) targeting nucleolin mRNA indicated that nucleolin was required for efficient virus production, viral DNA synthesis, and the expression of a late viral protein, with a correlation between the efficacy of knockdown and the effect on virus replication. In contrast, the level of neither global protein synthesis nor the replication of an unrelated virus (reovirus) was reduced in siRNA-treated cells. Taken together, our results indicate an association of nucleolin and UL44 in HCMV-infected cells and a role for nucleolin in viral DNA synthesis.
Collapse
Affiliation(s)
- Blair L. Strang
- Department of Biological Chemistry and Molecular Pharmacology, Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Steeve Boulant
- Department of Biological Chemistry and Molecular Pharmacology, Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| | - Donald M. Coen
- Department of Biological Chemistry and Molecular Pharmacology, Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115
| |
Collapse
|
42
|
Bouley J, Pionneau C, Varinot J, Biard D, Genestie C, Antoine M, Coulet F, Stern MH, Stoppa-Lyonnet D, Soubrier F. Proteomic analysis of BRCA1-depleted cell line reveals a putative role for replication protein A2 up-regulation in BRCA1
breast tumor development. Proteomics Clin Appl 2010; 4:489-98. [DOI: 10.1002/prca.200900107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 11/16/2009] [Accepted: 11/17/2009] [Indexed: 12/24/2022]
|
43
|
Nalabothula N, Indig FE, Carrier F. The Nucleolus Takes Control of Protein Trafficking Under Cellular Stress. MOLECULAR AND CELLULAR PHARMACOLOGY 2010; 2:203-212. [PMID: 21499571 PMCID: PMC3076688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The nucleolus is a highly dynamic nuclear substructure that was originally described as the site of ribosome biogenesis. The advent of proteomic analysis has now allowed the identification of over 4500 nucleolus associated proteins with only about 30% of them associated with ribogenesis (1). The great number of nucleolar proteins not associated with traditionally accepted nucleolar functions indicates a role for the nucleolus in other cellular functions such as mitosis, cell-cycle progression, cell proliferation and many forms of stress response including DNA repair (2). A number of recent reviews have addressed the pivotal role of the nucleolus in the cellular stress response (1, 3, 4). Here, we will focus on the role of Nucleolin and Nucleophosmin, two major components of the nucleolus, in response to genotoxic stress. Due to space constraint only a limited number of studies are cited. We thus apologize to all our colleagues whose works are not referenced here.
Collapse
Affiliation(s)
- Narasimharao Nalabothula
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland, Baltimore, School of Medicine, Department of Radiation Oncology, Baltimore, Maryland
| | - Fred E. Indig
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - France Carrier
- Marlene and Stewart Greenebaum Cancer Center, University of Maryland, Baltimore, School of Medicine, Department of Radiation Oncology, Baltimore, Maryland
| |
Collapse
|
44
|
Takashi Y, Kobayashi Y, Tanaka K, Tamura K. Arabidopsis replication protein A 70a is required for DNA damage response and telomere length homeostasis. PLANT & CELL PHYSIOLOGY 2009; 50:1965-1976. [PMID: 19812063 DOI: 10.1093/pcp/pcp140] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Replication protein A1 (RPA1/RPA70) forms a heterotrimeric complex together with RPA2/RPA32 and RPA3/RPA14 subunits which plays essential roles in various aspects of DNA metabolism including replication, repair, recombination and telomere maintenance. Compared with RPA70 in yeast and mammals, limited information is available about the factor in plants. In this study, we analyzed the functions of AtRPA70a, which is most similar to human RPA70 among four paralogs in Arabidopsis thaliana. RNA blot analysis showed that AtRPA70a is expressed ubiquitously in plant organs containing differentiated and meristematic tissues, while its expression was up-regulated in response to DNA damage stress. Yeast two-hybrid and co-immunoprecipitation analyses showed that AtRPA70a interacted preferentially with Arabidopsis RPA32a, one of two paralogs. Inactivation of AtRPA70a by T-DNA insertion did not affect growth under normal conditions, but resulted in increased sensitivity to genotoxic agents such as methylmethane sulfonate, bleomycin and hydroxyurea. Terminal restriction fragment analysis revealed that telomere lengths in an AtRPA70a-deficient line were significantly larger than in the wild type, whereas those in the mutant expressing antisense AtTERT (telomerase catalytic subunit gene) were shortened during successive generations. These results demonstrate that AtRPA70a is involved in repair of double-strand DNA breaks and possibly contributes to telomerase-dependent telomere length regulation.
Collapse
Affiliation(s)
- Yoshiyuki Takashi
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | | | | | | |
Collapse
|
45
|
Sato H, Kusumoto-Matsuo R, Ishii Y, Mori S, Nakahara T, Shinkai-Ouchi F, Kawana K, Fujii T, Taketani Y, Kanda T, Kukimoto I. Identification of nucleolin as a protein that binds to human papillomavirus type 16 DNA. Biochem Biophys Res Commun 2009; 387:525-30. [PMID: 19615975 DOI: 10.1016/j.bbrc.2009.07.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 07/13/2009] [Indexed: 12/12/2022]
Abstract
Transcription, replication, and segregation of human papillomaviruses (HPVs) are regulated by various host factors, but our understanding of host proteins that bind to the HPV genome is limited. Here we report the results of a search of cellular proteins that can associate with specific genomic regions of HPV type 16 (HPV16). We found that human nucleolin, an abundant nucleolar protein, was preferentially captured in vitro by an HPV16 genomic fragment from nucleotide positions (nt) 531-780. Electrophoretic mobility shift assays with a bacterially expressed nucleolin revealed that nucleolin bound to an HPV16 genomic region between nt 604 and 614 in a sequence-dependent manner. Chromatin immunoprecipitation analysis showed that both exogenous and endogenous nucleolin bound to a plasmid containing the HPV16 genomic region in HeLa cells. Furthermore, nucleolin associated with the HPV16 genome stably maintained in HPV16-infected W12 cells, suggesting that the nucleolin binding may be involved in the dynamics of the HPV genome in cells.
Collapse
Affiliation(s)
- Hidetaka Sato
- Pathogen Genomics Center, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Bates PJ, Laber DA, Miller DM, Thomas SD, Trent JO. Discovery and development of the G-rich oligonucleotide AS1411 as a novel treatment for cancer. Exp Mol Pathol 2009; 86:151-64. [PMID: 19454272 PMCID: PMC2716701 DOI: 10.1016/j.yexmp.2009.01.004] [Citation(s) in RCA: 593] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Indexed: 02/07/2023]
Abstract
Certain guanine-rich (G-rich) DNA and RNA molecules can associate intermolecularly or intramolecularly to form four stranded or "quadruplex" structures, which have unusual biophysical and biological properties. Several synthetic G-rich quadruplex-forming oligodeoxynucleotides have recently been investigated as therapeutic agents for various human diseases. We refer to these biologically active G-rich oligonucleotides as aptamers because their activities arise from binding to protein targets via shape-specific recognition (analogous to antibody-antigen binding). As therapeutic agents, the G-rich aptamers may have some advantages over monoclonal antibodies and other oligonucleotide-based approaches. For example, quadruplex oligonucleotides are non-immunogenic, heat stable and they have increased resistance to serum nucleases and enhanced cellular uptake compared to unstructured sequences. In this review, we describe the characteristics and activities of G-rich oligonucleotides. We also give a personal perspective on the discovery and development of AS1411, an antiproliferative G-rich phosphodiester oligonucleotide that is currently being tested as an anticancer agent in Phase II clinical trials. This molecule functions as an aptamer to nucleolin, a multifunctional protein that is highly expressed by cancer cells, both intracellularly and on the cell surface. Thus, the serendipitous discovery of the G-rich oligonucleotides also led to the identification of nucleolin as a new molecular target for cancer therapy.
Collapse
Affiliation(s)
- Paula J Bates
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, Louisville, Kentucky 40202, USA.
| | | | | | | | | |
Collapse
|
47
|
Abstract
The diphosphoinositol polyphosphates ("inositol pyrophosphates") are a specialized subgroup of the inositol phosphate signaling family. This review proposes that many of the current data concerning the metabolic turnover and biological effects of the diphosphoinositol polyphosphates are linked by a common theme: these polyphosphates act as metabolic messengers. This review will also discuss the latest proposals concerning possible molecular mechanisms of action of this intriguing class of molecules.
Collapse
Affiliation(s)
- Stephen B Shears
- Inositide Signaling Group, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, NC 27709, USA.
| |
Collapse
|
48
|
Storck S, Thiry M, Bouvet P. Conditional knockout of nucleolin in DT40 cells reveals the functional redundancy of its RNA-binding domains. Biol Cell 2009; 101:153-67. [PMID: 18637790 DOI: 10.1042/bc20080054] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
BACKGROUND INFORMATION Nucleolin is a major nucleolar protein which is highly expressed in rapidly dividing cells and cancer cell lines. This protein is claimed to be multifunctional and could play a role in rRNA (ribosomal RNA) synthesis, as well as in cell division or response to cellular stresses. Therefore, how nucleolin influences cell proliferation remained elusive so far. RESULTS We have generated conditional nucleolin-knockout cells using the chicken B lymphocyte cell line DT40. Our results indicate that nucleolin is absolutely required for the proliferation and for the survival of these cells. Depletion of nucleolin drastically inhibits rDNA (ribosomal DNA) transcription while only slightly affecting pre-rRNA processing. This inhibition is accompanied by modifications of the shape and the structure of the nucleolus. The analysis of mutants of nucleolin, which lack two or three RNA-binding domains, shows that these domains harbour redundant functions and that nucleolin's roles in transcription, rRNA maturation and nucleolar shape can be partially uncoupled. CONCLUSIONS The function of nucleolin in ribosomal synthesis could account for its effect on cell division and survival, but this vital role does not seem to be linked to sequence-specific RNA binding.
Collapse
|
49
|
Johnson JS, Samulski RJ. Enhancement of adeno-associated virus infection by mobilizing capsids into and out of the nucleolus. J Virol 2009; 83:2632-44. [PMID: 19109385 PMCID: PMC2648275 DOI: 10.1128/jvi.02309-08] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 12/18/2008] [Indexed: 11/20/2022] Open
Abstract
Adeno-associated virus (AAV) serotypes are being tailored for numerous therapeutic applications, but the parameters governing the subcellular fate of even the most highly characterized serotype, AAV2, remain unclear. To understand how cellular conditions control capsid trafficking, we have tracked the subcellular fate of recombinant AAV2 (rAAV2) vectors using confocal immunofluorescence, three-dimensional infection analysis, and subcellular fractionation. Here we report that a population of rAAV2 virions enters the nucleus and accumulates in the nucleolus after infection, whereas empty capsids are excluded from nuclear entry. Remarkably, after subcellular fractionation, virions accumulating in nucleoli were found to retain infectivity in secondary infections. Proteasome inhibitors known to enhance transduction were found to potentiate nucleolar accumulation. In contrast, hydroxyurea, which also increases transduction, mobilized virions into the nucleoplasm, suggesting that two separate pathways influence vector delivery in the nucleus. Using a small interfering RNA (siRNA) approach, we then evaluated whether nucleolar proteins B23/nucleophosmin and nucleolin, previously shown to interact with AAV2 capsids, affect trafficking and transduction efficiency. Similar to effects observed with proteasome inhibition, siRNA-mediated knockdown of nucleophosmin potentiated nucleolar accumulation and increased transduction 5- to 15-fold. Parallel to effects from hydroxyurea, knockdown of nucleolin mobilized capsids to the nucleoplasm and increased transduction 10- to 30-fold. Moreover, affecting both pathways simultaneously using drug and siRNA combinations was synergistic and increased transduction over 50-fold. Taken together, these results support the hypothesis that rAAV2 virions enter the nucleus intact and can be sequestered in the nucleolus in stable form. Mobilization from the nucleolus to nucleoplasmic sites likely permits uncoating and subsequent gene expression or genome degradation. In summary, with these studies we have refined our understanding of AAV2 trafficking dynamics and have identified cellular parameters that mobilize virions in the nucleus and significantly influence AAV infection.
Collapse
Affiliation(s)
- Jarrod S Johnson
- Gene Therapy Center and Department of Pharmacology, The University of North Carolina at Chapel Hill, 7119 Thurston Bowles, CB 7352, Chapel Hill, North Carolina 27599-7352, USA
| | | |
Collapse
|
50
|
Stepanova V, Lebedeva T, Kuo A, Yarovoi S, Tkachuk S, Zaitsev S, Bdeir K, Dumler I, Marks MS, Parfyonova Y, Tkachuk VA, Higazi AAR, Cines DB. Nuclear translocation of urokinase-type plasminogen activator. Blood 2008; 112:100-10. [PMID: 18337556 PMCID: PMC2435680 DOI: 10.1182/blood-2007-07-104455] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Accepted: 02/01/2008] [Indexed: 01/16/2023] Open
Abstract
Urokinase-type plasminogen activator (uPA) participates in diverse (patho)physiological processes through intracellular signaling events that affect cell adhesion, migration, and proliferation, although the mechanisms by which these occur are only partially understood. Here we report that upon cell binding and internalization, single-chain uPA (scuPA) translocates to the nucleus within minutes. Nuclear translocation does not involve proteolytic activation or degradation of scuPA. Neither the urokinase receptor (uPAR) nor the low-density lipoprotein-related receptor (LRP) is required for nuclear targeting. Rather, translocation involves the binding of scuPA to the nucleocytoplasmic shuttle protein nucleolin through a region containing the kringle domain. RNA interference and mutational analysis demonstrate that nucleolin is required for the nuclear transport of scuPA. Furthermore, nucleolin is required for the induction smooth muscle alpha-actin (alpha-SMA) by scuPA. These data reveal a novel pathway by which uPA is rapidly translocated to the nucleus where it might participate in regulating gene expression.
Collapse
Affiliation(s)
- Victoria Stepanova
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia 19104, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|