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Liu Y, Yao Z, Lian G, Yang P. Biomolecular phase separation in stress granule assembly and virus infection. Acta Biochim Biophys Sin (Shanghai) 2023; 55:1099-1118. [PMID: 37401177 PMCID: PMC10415189 DOI: 10.3724/abbs.2023117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/06/2023] [Indexed: 07/05/2023] Open
Abstract
Liquid-liquid phase separation (LLPS) has emerged as a crucial mechanism for cellular compartmentalization. One prominent example of this is the stress granule. Found in various types of cells, stress granule is a biomolecular condensate formed through phase separation. It comprises numerous RNA and RNA-binding proteins. Over the past decades, substantial knowledge has been gained about the composition and dynamics of stress granules. SGs can regulate various signaling pathways and have been associated with numerous human diseases, such as neurodegenerative diseases, cancer, and infectious diseases. The threat of viral infections continues to loom over society. Both DNA and RNA viruses depend on host cells for replication. Intriguingly, many stages of the viral life cycle are closely tied to RNA metabolism in human cells. The field of biomolecular condensates has rapidly advanced in recent times. In this context, we aim to summarize research on stress granules and their link to viral infections. Notably, stress granules triggered by viral infections behave differently from the canonical stress granules triggered by sodium arsenite (SA) and heat shock. Studying stress granules in the context of viral infections could offer a valuable platform to link viral replication processes and host anti-viral responses. A deeper understanding of these biological processes could pave the way for innovative interventions and treatments for viral infectious diseases. They could potentially bridge the gap between basic biological processes and interactions between viruses and their hosts.
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Affiliation(s)
- Yi Liu
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Zhiying Yao
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Guiwei Lian
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
| | - Peiguo Yang
- />Westlake Laboratory of Life Sciences and BiomedicineSchool of Life SciencesWestlake UniversityHangzhou310030China
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Wang L, Guzmán M, Sola I, Enjuanes L, Zuñiga S. Cytoplasmic ribonucleoprotein complexes, RNA helicases and coronavirus infection. FRONTIERS IN VIROLOGY 2022. [DOI: 10.3389/fviro.2022.1078454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
RNA metabolism in the eukaryotic cell includes the formation of ribonucleoprotein complexes (RNPs) that, depending on their protein components, have a different function. Cytoplasmic RNPs, such as stress granules (SGs) or P-bodies (PBs) are quite relevant during infections modulating viral and cellular RNA expression and as key players in the host cell antiviral response. RNA helicases are abundant components of RNPs and could have a significant effect on viral infection. This review focuses in the role that RNPs and RNA helicases have during coronavirus (CoVs) infection. CoVs are emerging highly pathogenic viruses with a large single-stranded RNA genome. During CoV infection, a complex network of RNA-protein interactions in different RNP structures is established. In general, RNA helicases and RNPs have an antiviral function, but there is limited knowledge on whether the viral protein interactions with cell components are mediators of this antiviral effect or are part of the CoV antiviral counteraction mechanism. Additional data is needed to elucidate the role of these RNA-protein interactions during CoV infection and their potential contribution to viral replication or pathogenesis.
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Gaete-Argel A, Velásquez F, Márquez CL, Rojas-Araya B, Bueno-Nieto C, Marín-Rojas J, Cuevas-Zúñiga M, Soto-Rifo R, Valiente-Echeverría F. Tellurite Promotes Stress Granules and Nuclear SG-Like Assembly in Response to Oxidative Stress and DNA Damage. Front Cell Dev Biol 2021; 9:622057. [PMID: 33681200 PMCID: PMC7928414 DOI: 10.3389/fcell.2021.622057] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 01/21/2021] [Indexed: 12/13/2022] Open
Abstract
Tellurium oxyanion, tellurite (TeO3–2), is a highly toxic compound for many organisms. Its presence in the environment has increased over the past years due to industrial manufacturing processes and has been associated with adverse effects on human health. Although tellurite induces the phosphorylation of eIF2α, DNA damage and oxidative stress, the molecular mechanisms related to the cellular responses to tellurite-induced stress are poorly understood. In this work, we evaluated the ability of tellurite to induce phosphorylation of eIF2α, stress granules (SGs) assembly and their relationship with DNA damage in U2OS cells. We demonstrate that tellurite promotes the assembly of bona fide cytoplasmic SGs. Unexpectedly, tellurite also induces the assembly of nuclear SGs. Interestingly, we observed that the presence of tellurite-induced nuclear SGs correlates with γH2AX foci. However, although H2O2 also induce DNA damage, no nuclear SGs were observed. Our data show that tellurite promotes the assembly of cytoplasmic and nuclear SGs in response to oxidative stress and DNA damage, revealing a new aspect of cellular stress response mediated by the assembly of nuclear stress granules.
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Affiliation(s)
- Aracelly Gaete-Argel
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Felipe Velásquez
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Chantal L Márquez
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Barbara Rojas-Araya
- HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Constanza Bueno-Nieto
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile
| | - Josefina Marín-Rojas
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Miguel Cuevas-Zúñiga
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile
| | - Ricardo Soto-Rifo
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Fernando Valiente-Echeverría
- Molecular and Cellular Virology Laboratory, Faculty of Medicine, Virology Program, Institute of Biomedical Sciences, Universidad de Chile, Santiago, Chile.,HIV/AIDS Workgroup, Faculty of Medicine, Universidad de Chile, Santiago, Chile
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Dominguez CE, Cunningham D, Chandler DS. SMN regulation in SMA and in response to stress: new paradigms and therapeutic possibilities. Hum Genet 2017; 136:1173-1191. [PMID: 28852871 PMCID: PMC6201753 DOI: 10.1007/s00439-017-1835-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 08/07/2017] [Indexed: 12/12/2022]
Abstract
Low levels of the survival of motor neuron (SMN) protein cause the neurodegenerative disease spinal muscular atrophy (SMA). SMA is a pediatric disease characterized by spinal motor neuron degeneration. SMA exhibits several levels of severity ranging from early antenatal fatality to only mild muscular weakness, and disease prognosis is related directly to the amount of functional SMN protein that a patient is able to express. Current therapies are being developed to increase the production of functional SMN protein; however, understanding the effect that natural stresses have on the production and function of SMN is of critical importance to ensuring that these therapies will have the greatest possible effect for patients. Research has shown that SMN, both on the mRNA and protein level, is highly affected by cellular stress. In this review we will summarize the research that highlights the roles of SMN in the disease process and the response of SMN to various environmental stresses.
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Affiliation(s)
- Catherine E Dominguez
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA
| | - David Cunningham
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA
| | - Dawn S Chandler
- Molecular, Cellular and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA.
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH, 43205, USA.
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA.
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Heck TG, Scomazzon SP, Nunes PR, Schöler CM, da Silva GS, Bittencourt A, Faccioni-Heuser MC, Krause M, Bazotte RB, Curi R, Homem de Bittencourt PI. Acute exercise boosts cell proliferation and the heat shock response in lymphocytes: correlation with cytokine production and extracellular-to-intracellular HSP70 ratio. Cell Stress Chaperones 2017; 22:271-291. [PMID: 28251488 PMCID: PMC5352601 DOI: 10.1007/s12192-017-0771-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/24/2017] [Accepted: 01/31/2017] [Indexed: 12/23/2022] Open
Abstract
Exercise stimulates immune responses, but the appropriate "doses" for such achievements are unsettled. Conversely, in metabolic tissues, exercise improves the heat shock (HS) response, a universal cytoprotective response to proteostasis challenges that are centred on the expression of the 70-kDa family of intracellular heat shock proteins (iHSP70), which are anti-inflammatory. Concurrently, exercise triggers the export of HSP70 towards the extracellular milieu (eHSP70), where they work as pro-inflammatory cytokines. As the HS response is severely compromised in chronic degenerative diseases of inflammatory nature, we wondered whether acute exercise bouts of different intensities could alter the HS response of lymphocytes from secondary lymphoid organs and whether this would be related to immunoinflammatory responses. Adult male Wistar rats swam for 20 min at low, moderate, high or strenuous intensities as per an overload in tail base. Controls remained at rest under the same conditions. Afterwards, mesenteric lymph node lymphocytes were assessed for the potency of the HS response (42 °C for 2 h), NF-κB binding activity, mitogen-stimulated proliferation and cytokine production. Exercise stimulated cell proliferation in an "inverted-U" fashion peaking at moderate load, which was paralleled by suppression of NF-κB activation and nuclear location, and followed by enhanced HS response in relation to non-exercised animals. Comparative levels of eHSP70 to iHSP70 (H-index) matched IL-2/IL-10 ratios. We conclude that exercise, in a workload-dependent way, stimulates immunoinflammatory performance of lymphocytes of tissues far from the circulation and this is associated with H-index of stress response, which is useful to assess training status and immunosurveillance balance.
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Affiliation(s)
- Thiago Gomes Heck
- Physiology Research Group, Department of Life Sciences, Postgraduate Program in Integral Attention to Health, Regional University of the Northwestern Rio Grande do Sul State, Rua do Comércio, 3000, Ijuí, RS, 98700-000, Brazil.
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil.
| | - Sofia Pizzato Scomazzon
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil
- Department of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133, Rome, Italy
| | - Patrícia Renck Nunes
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil
| | - Cinthia Maria Schöler
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil
| | - Gustavo Stumpf da Silva
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil
| | - Aline Bittencourt
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil
| | - Maria Cristina Faccioni-Heuser
- Department of Morphological Sciences, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Mauricio Krause
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil
| | - Roberto Barbosa Bazotte
- Department of Pharmacology and Therapeutics, State University of Maringá, Maringá, PR, Brazil
| | - Rui Curi
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, 05508-900, Brazil
- Institute of Physical Activity Sciences and Sports, Cruzeiro do Sul University, Rua Galvão Bueno, 868 - 13° Andar, Bloco B, Sala 1302, Liberdade, São Paulo, SP, 01506-000, Brazil
| | - Paulo Ivo Homem de Bittencourt
- Laboratory of Cellular Physiology, Department of Physiology, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Rua Sarmento Leite, 500 2nd floor, suite 350 lab 02, Porto Alegre, RS, 90050-170, Brazil.
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Relationships between Stress Granules, Oxidative Stress, and Neurodegenerative Diseases. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:1809592. [PMID: 28194255 PMCID: PMC5286466 DOI: 10.1155/2017/1809592] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 12/28/2016] [Indexed: 12/13/2022]
Abstract
Cytoplasmic stress granules (SGs) are critical for facilitating stress responses and for preventing the accumulation of misfolded proteins. SGs, however, have been linked to the pathogenesis of neurodegenerative diseases, in part because SGs share many components with neuronal granules. Oxidative stress is one of the conditions that induce SG formation. SGs regulate redox levels, and SG formation in turn is differently regulated by various types of oxidative stress. These associations and other evidences suggest that SG formation contributes to the development of neurodegenerative diseases. In this paper, we review the regulation of SG formation/assembly and discuss the interactions between oxidative stress and SG formation. We then discuss the links between SGs and neurodegenerative diseases and the current therapeutic approaches for neurodegenerative diseases that target SGs.
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Neuronal serotonin release triggers the heat shock response in C. elegans in the absence of temperature increase. Curr Biol 2014; 25:163-174. [PMID: 25557666 DOI: 10.1016/j.cub.2014.11.040] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Revised: 10/13/2014] [Accepted: 11/17/2014] [Indexed: 01/07/2023]
Abstract
BACKGROUND Cellular mechanisms aimed at repairing protein damage and maintaining homeostasis, widely understood to be triggered by the damage itself, have recently been shown to be under cell nonautonomous control in the metazoan C. elegans. The heat shock response (HSR) is one such conserved mechanism, activated by cells upon exposure to proteotoxic conditions such as heat. Previously, we had shown that this conserved cytoprotective response is regulated by the thermosensory neuronal circuitry of C. elegans. Here, we investigate the mechanisms and physiological relevance of neuronal control. RESULTS By combining optogenetic methods with live visualization of the dynamics of the heat shock transcription factor (HSF1), we show that excitation of the AFD thermosensory neurons is sufficient to activate HSF1 in another cell, even in the absence of temperature increase. Excitation of the AFD thermosensory neurons enhances serotonin release. Serotonin release elicited by direct optogenetic stimulation of serotonergic neurons activates HSF1 and upregulates molecular chaperones through the metabotropic serotonin receptor SER-1. Consequently, excitation of serotonergic neurons alone can suppress protein misfolding in C. elegans peripheral tissue. CONCLUSIONS These studies imply that thermosensory activity coupled to serotonergic signaling is sufficient to activate the protective HSR prior to frank proteotoxic damage. The ability of neurosensory release of serotonin to control cellular stress responses and activate HSF1 has powerful implications for the treatment of protein conformation diseases.
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Chafekar SM, Duennwald ML. Impaired heat shock response in cells expressing full-length polyglutamine-expanded huntingtin. PLoS One 2012; 7:e37929. [PMID: 22649566 PMCID: PMC3359295 DOI: 10.1371/journal.pone.0037929] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 04/30/2012] [Indexed: 01/02/2023] Open
Abstract
The molecular mechanisms by which polyglutamine (polyQ)-expanded huntingtin (Htt) causes neurodegeneration in Huntington's disease (HD) remain unclear. The malfunction of cellular proteostasis has been suggested as central in HD pathogenesis and also as a target of therapeutic interventions for the treatment of HD. We present results that offer a previously unexplored perspective regarding impaired proteostasis in HD. We find that, under non-stress conditions, the proteostatic capacity of cells expressing full length polyQ-expanded Htt is adequate. Yet, under stress conditions, the presence of polyQ-expanded Htt impairs the heat shock response, a key component of cellular proteostasis. This impaired heat shock response results in a reduced capacity to withstand the damage caused by cellular stress. We demonstrate that in cells expressing polyQ-expanded Htt the levels of heat shock transcription factor 1 (HSF1) are reduced, and, as a consequence, these cells have an impaired a heat shock response. Also, we found reduced HSF1 and HSP70 levels in the striata of HD knock-in mice when compared to wild-type mice. Our results suggests that full length, non-aggregated polyQ-expanded Htt blocks the effective induction of the heat shock response under stress conditions and may thus trigger the accumulation of cellular damage during the course of HD pathogenesis.
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Affiliation(s)
| | - Martin L. Duennwald
- Regenerative Biology Program, Boston Biomedical Research Institute, Watertown, Massachusetts, United States of America
- * E-mail:
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Zorzi E, Bonvini P. Inducible hsp70 in the regulation of cancer cell survival: analysis of chaperone induction, expression and activity. Cancers (Basel) 2011; 3:3921-56. [PMID: 24213118 PMCID: PMC3763403 DOI: 10.3390/cancers3043921] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/26/2011] [Accepted: 10/10/2011] [Indexed: 12/31/2022] Open
Abstract
Understanding the mechanisms that control stress is central to realize how cells respond to environmental and physiological insults. All the more important is to reveal how tumour cells withstand their harsher growth conditions and cope with drug-induced apoptosis, since resistance to chemotherapy is the foremost complication when curing cancer. Intensive research on tumour biology over the past number of years has provided significant insights into the molecular events that occur during oncogenesis, and resistance to anti-cancer drugs has been shown to often rely on stress response and expression of inducible heat shock proteins (HSPs). However, with respect to the mechanisms guarding cancer cells against proteotoxic stresses and the modulatory effects that allow their survival, much remains to be defined. Heat shock proteins are molecules responsible for folding newly synthesized polypeptides under physiological conditions and misfolded proteins under stress, but their role in maintaining the transformed phenotype often goes beyond their conventional chaperone activity. Expression of inducible HSPs is known to correlate with limited sensitivity to apoptosis induced by diverse cytotoxic agents and dismal prognosis of several tumour types, however whether cancer cells survive because of the constitutive expression of heat shock proteins or the ability to induce them when adapting to the hostile microenvironment remains to be elucidated. Clear is that tumours appear nowadays more "addicted" to heat shock proteins than previously envisaged, and targeting HSPs represents a powerful approach and a future challenge for sensitizing tumours to therapy. This review will focus on the anti-apoptotic role of heat shock 70kDa protein (Hsp70), and how regulatory factors that control inducible Hsp70 synthesis, expression and activity may be relevant for response to stress and survival of cancer cells.
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Affiliation(s)
- Elisa Zorzi
- OncoHematology Clinic of Pediatrics, University-Hospital of Padova, 35100 Padova, Italy; E-Mail:
| | - Paolo Bonvini
- OncoHematology Clinic of Pediatrics, University-Hospital of Padova, 35100 Padova, Italy; E-Mail:
- Fondazione Città della Speranza, 36030 Monte di Malo, Vicenza, Italy
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Pandey R, Mukerji M. From 'JUNK' to Just Unexplored Noncoding Knowledge: the case of transcribed Alus. Brief Funct Genomics 2011; 10:294-311. [DOI: 10.1093/bfgp/elr029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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11
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Discovery of a new RNA-containing nuclear structure in UVC-induced apoptotic cells by integrated laser electron microscopy. Biol Cell 2009; 101:287-99. [PMID: 18823283 DOI: 10.1042/bc20080076] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND INFORMATION Treatment of cells with UVC radiation leads to the formation of DNA cross-links which, if not repaired, can lead to apoptosis. gamma-H2AX and cleaved caspase 3 are proteins formed during UVC-induced DNA damage and apoptosis respectively. The present study sets out to identify early morphological markers of apoptosis using a new method of correlative microscopy, ILEM (integrated laser electron microscopy). Cleaved caspase 3 and gamma-H2AX were immunofluorescently labelled to mark the cells of interest. These cells were subsequently searched in the fluorescence mode of the ILEM and further analysed at high resolution with TEM (transmission electron microscopy). RESULTS Following the treatment of HUVECs (human umbilical vein endothelial cells) with UVC radiation, in the majority of the cells gamma-H2AX was formed, whereas only in a subset of cells caspase 3 was activated. In severely damaged cells with high levels of gamma-H2AX a round, electron-dense nuclear structure was found, which was hitherto not identified in UV-stressed cells. This structure exists only in nuclei of cells containing cleaved caspase 3 and is present during all stages of the apoptotic process. Energy-loss imaging showed that the nuclear structure accumulates phosphorus, indicating that it is rich in nucleic acids. Because the nuclear structure did not label for DNA and was not affected by regressive EDTA treatment, it is suggested that the UV-induced nuclear structure contains a high amount of RNA. CONCLUSIONS Because the UV-induced nuclear structure was only found in cells labelled for cleaved caspase 3 it is proposed as an electron microscopic marker for all stages of apoptosis. Such a marker will especially facilitate the screening for early apoptotic cells, which lack the well-known hallmarks of apoptosis within a cell population. It also raises new questions on the mechanisms involved in the UV-induced apoptotic pathway.
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McCollum AK, Lukasiewicz KB, Teneyck CJ, Lingle WL, Toft DO, Erlichman C. Cisplatin abrogates the geldanamycin-induced heat shock response. Mol Cancer Ther 2008; 7:3256-64. [PMID: 18852129 DOI: 10.1158/1535-7163.mct-08-0157] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Benzoquinone ansamycin antibiotics such as geldanamycin (GA) bind to the NH(2)-terminal ATP-binding domain of heat shock protein (Hsp) 90 and inhibit its chaperone functions. Despite in vitro and in vivo studies indicating promising antitumor activity, derivatives of GA, including 17-allylaminogeldanamycin (17-AAG), have shown little clinical efficacy as single agents. Thus, combination studies of 17-AAG and several cancer chemotherapeutics, including cisplatin (CDDP), have begun. In colony-forming assays, the combination of CDDP and GA or 17-AAG was synergistic and caused increased apoptosis compared with each agent alone. One measurable response that results from treatment with Hsp90-targeted agents is the induction of a heat shock factor-1 (HSF-1) heat shock response. Treatment with GA + CDDP revealed that CDDP suppresses up-regulation of HSF-1 transcription, causing decreased levels of stress-inducible proteins such as Hsp27 and Hsp70. However, CDDP treatment did not prevent trimerization and nuclear localization of HSF-1 but inhibited DNA binding of HSF-1 as shown by chromatin immunoprecipitation. Melphalan, but not camptothecin, caused similar inhibition of GA-induced HSF-1-mediated Hsp70 up-regulation. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt cell survival assays revealed that deletion of Hsp70 caused increased sensitivity to GA (Hsp70(+/+) IC(50) = 63.7 +/- 14.9 nmol/L and Hsp70(-/-) IC(50) = 4.3 +/- 2.9 nmol/L), which confirmed that a stress response plays a critical role in decreasing GA sensitivity. Our results suggest that the synergy of GA + CDDP is due, in part, to CDDP-mediated abrogation of the heat shock response through inhibition of HSF-1 activity. Clinical modulation of the HSF-1-mediated heat shock response may enhance the efficacy of Hsp90-directed therapy.
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Affiliation(s)
- Andrea K McCollum
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA
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Abstract
Human bystin was identified as a cytoplasmic protein directly binding to trophinin, a cell adhesion molecule potentially involved in human embryo implantation. Although the trophinin gene is unique to mammals, the bystin gene (BYSL) is conserved across eukaryotes. Recent studies show that bystin plays a key role during the transition from silent trophectoderm to an active trophoblast upon trophinin-mediated cell adhesion. Bystin gene knockout and knockdown experiments demonstrate that bystin is essential for embryonic stem cell survival and trophectoderm development in the mouse. Furthermore, biochemical analysis of bystin in human cancer cells and mouse embryos indicates a function in ribosomal biogenesis, specifically in processing of 18S RNA in the 40S subunit. Strong evidence that BYSL is a target of c-MYC is consistent with a role for bystin in rapid protein synthesis, which is required for actively growing cells.
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14
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Miyoshi M, Okajima T, Matsuda T, Fukuda M, Nadano D. Bystin in human cancer cells: intracellular localization and function in ribosome biogenesis. Biochem J 2007; 404:373-81. [PMID: 17381424 PMCID: PMC1896285 DOI: 10.1042/bj20061597] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Although bystin has been identified as a protein potentially involved in embryo implantation (a process unique to mammals) in humans, the bystin gene is evolutionarily conserved from yeast to humans. DNA microarray data indicates that bystin is overexpressed in human cancers, suggesting that it promotes cell growth. We undertook RT (reverse transcription)-PCR and immunoblotting, and confirmed that bystin mRNA and protein respectively are expressed in human cancer cell lines, including HeLa. Subcellular fractionation identified bystin protein as nuclear and cytoplasmic, and immunofluorescence showed that nuclear bystin localizes mainly in the nucleolus. Sucrose gradient ultracentrifugation of total cytoplasmic ribosomes revealed preferential association of bystin with the 40S subunit fractions. To analyse its function, bystin expression in cells was suppressed by RNAi (RNA interference). Pulse-chase analysis of ribosomal RNA processing suggested that bystin knockdown delays processing of 18S ribosomal RNA, a component of the 40S subunit. Furthermore, this knockdown significantly inhibited cell proliferation. Our findings suggest that bystin may promote cell proliferation by facilitating ribosome biogenesis, specifically in the production of the 40S subunit. Localization of bystin to the nucleolus, the site of ribosome biogenesis, was blocked by low concentrations of actinomycin D, a reagent that causes nucleolar stress. When bystin was transiently overexpressed in HeLa cells subjected to nucleolar stress, nuclear bystin was included in particles different from the nuclear stress granules induced by heat shock. In contrast, cytoplasmic bystin was barely affected by nucleolar stress. These results suggest that, while bystin may play multiple roles in mammalian cells, a conserved function is to facilitate ribosome biogenesis required for cell growth.
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Affiliation(s)
- Masaya Miyoshi
- *Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Tetsuya Okajima
- *Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Tsukasa Matsuda
- *Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Michiko N. Fukuda
- †Burnham Institute for Medical Research, North Torrey Pines Road, La Jolla, CA 92037, U.S.A
| | - Daita Nadano
- *Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
- To whom correspondence should be addressed (email )
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Madon PF, Athalye AS, Parikh FR. Polymorphic variants on chromosomes probably play a significant role in infertility. Reprod Biomed Online 2005; 11:726-32. [PMID: 16417737 DOI: 10.1016/s1472-6483(10)61691-4] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Polymorphic variants on chromosomes are considered 'normal', as heterochromatin has no coding potential and nucleolar organizing regions (NOR) contain genes coding for rRNA. Variants have been reported in infertility and recurrent abortions. With refined molecular techniques, genes for fertility and viability are now thought to reside in heterochromatin. DNA sequence analysis of human chromosome 9 has shown that it is highly structurally polymorphic, with many intrachromosomal and interchromosomal duplications, and contains the largest autosomal block of heterochromatin. Transcriptional activation of constitutive heterochromatic domains of the human genome in response to environmental stress was reported recently. Heat shock triggers the assembly of nuclear stress bodies on the pericentromeric heterochromatin of human chromosomes including chromosome 9. These are characterized by an epigenetic status typical of euchromatic regions. On acrocentric chromosomes, NOR-associated protein count and morphology was reported to separate benign and malignant melanocytic lesions. Hence all variants may not be 'normal'. The present study of karyotyping 842 individuals attending an IVF clinic with primary infertility or repeated miscarriages, showed polymorphic variants in 28.82% of males and 17.19% of females, which was quite high. It is suggested that variants should not be ignored by cytogeneticists. Screening prospective gamete donors for chromosome variants may help enhance the success of IVF.
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Affiliation(s)
- Prochi F Madon
- Department of Assisted Reproduction and Genetics, Jaslok Hospital and Research Centre, Mumbai 400026, India.
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Candé C, Vahsen N, Métivier D, Tourrière H, Chebli K, Garrido C, Tazi J, Kroemer G. Regulation of cytoplasmic stress granules by apoptosis-inducing factor. J Cell Sci 2004; 117:4461-8. [PMID: 15316071 DOI: 10.1242/jcs.01356] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Stress granules (SG) are dynamic cytoplasmic foci in which stalled translation initiation complexes accumulate. In conditions of acute cellular redox, stress cells manipulated to lose the expression of apoptosis-inducing factor (AIF) nucleate SG signature proteins (e.g. TIA-1, PABP1) more efficiently than AIF-positive controls. AIF also inhibited SG formation induced by the RasGAP-associated endoribonuclease G3BP. Retransfection of mouse AIF into cells subjected to human AIF-specific siRNA revealed that only AIF imported into mitochondria could repress SGs and that redox-active domains of AIF, which are dispensable for its apoptogenic action, were required for SG inhibition. In response to oxidative stress, AIF-negative cells were found to deplete non-oxidized glutathione more rapidly than AIF-expressing cells. Exogenous supplementation of glutathione inhibited SG formation elicited by arsenate or G3BP. Together, these data suggest that the oxidoreductase function of AIF is required for the maintenance of glutathione levels in stress conditions and that glutathione is a major regulator of SG.
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Affiliation(s)
- Céline Candé
- CNRS-UMR8125, Institut Gustave Roussy, 39 rue Camille-Desmoulins, 94805 Villejuif, France
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