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Nishimura E, Kawahara M, Kodaira R, Kume M, Arai N, Nishikawa JI, Ohyama T. S-like ribonuclease gene expression in carnivorous plants. PLANTA 2013; 238:955-67. [PMID: 23959189 DOI: 10.1007/s00425-013-1945-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 07/30/2013] [Indexed: 05/09/2023]
Abstract
Functions of S-like ribonucleases (RNases) differ considerably from those of S-RNases that function in self-incompatibility. Expression of S-like RNases is usually induced by low nutrition, vermin damage or senescence. However, interestingly, an Australian carnivorous plant Drosera adelae (a sundew), which traps prey with a sticky digestive liquid, abundantly secretes an S-like RNase DA-I in the digestive liquid even in ordinary states. Here, using D. adelae, Dionaea muscipula (Venus flytrap) and Cephalotus follicularis (Australian pitcher plant), we show that carnivorous plants use S-like RNases for carnivory: the gene da-I encoding DA-I and its ortholog cf-I of C. follicularis are highly expressed and constitutively active in each trap/digestion organ, while the ortholog dm-I of D. muscipula becomes highly active after trapping insects. The da-I promoter is unmethylated only in its trap/digestion organ, glandular tentacles (which comprise a small percentage of the weight of the whole plant), but methylated in other organs, which explains the glandular tentacles-specific expression of the gene and indicates a very rare gene regulation system. In contrast, the promoters of dm-I, which shows induced expression, and cf-I, which has constitutive expression, were not methylated in any organs examined. Thus, it seems that the regulatory mechanisms of the da-I, dm-I and cf-I genes differ from each other and do not correlate with the phylogenetic relationship. The current study suggests that under environmental pressure in specific habitats carnivorous plants have managed to evolve their S-like RNase genes to function in carnivory.
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152
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Shcherbik N. Golgi-mediated glycosylation determines residency of the T2 RNase Rny1p in Saccharomyces cerevisiae. Traffic 2013; 14:1209-27. [PMID: 24102742 DOI: 10.1111/tra.12122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 09/16/2013] [Accepted: 09/18/2013] [Indexed: 12/20/2022]
Abstract
The role of glycosylation in the function of the T2 family of RNases is not well understood. In this work, we examined how glycosylation affects the progression of the T2 RNase Rny1p through the secretory pathway in Saccharomyces cerevisiae. We found that Rny1p requires entering into the ER first to become active and uses the adaptor protein Erv29p for packaging into COPII vesicles and transport to the Golgi apparatus. While inside the ER, Rny1p undergoes initial N-linked core glycosylation at four sites, N37, N70, N103 and N123. Rny1p transport to the Golgi results in the further attachment of high-glycans. Whereas modifications with glycans are dispensable for the nucleolytic activity of Rny1p, Golgi-mediated modifications are critical for its extracellular secretion. Failure of Golgi-specific glycosylation appears to direct Rny1p to the vacuole as an alternative destination and/or site of terminal degradation. These data reveal a previously unknown function of Golgi glycosylation in a T2 RNase as a sorting and secretion signal.
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Affiliation(s)
- Natalia Shcherbik
- Department of Cell Biology, School of Osteopathic Medicine, Rowan University, 2 Medical Center Drive, Stratford, NJ 08084, USA.
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153
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Loss of function of Ribonuclease T2, an ancient and phylogenetically conserved RNase, plays a crucial role in ovarian tumorigenesis. Proc Natl Acad Sci U S A 2013; 110:8140-5. [PMID: 23630276 DOI: 10.1073/pnas.1222079110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
In recent years, the role played by the stromal microenvironment has been given growing attention in order to achieve a full understanding of cancer initiation and progression. Because cancer is a tissue-based disease, the integrity of tissue architecture is a major constraint toward cancer growth. Indeed, a large contribution of the natural resistance to cancer stems from stromal microenvironment components, the dysregulation of which can facilitate cancer occurrence. For instance, recent experimental evidence has highlighted the involvement of stromal cells in ovarian carcinogenesis, as epitomized by ovarian xenografts obtained by a double KO of the murine Dicer and Pten genes. Likewise, we reported the role of an ancient extracellular RNase, called Ribonuclease T2 (RNASET2), within the ovarian stromal microenvironment. Indeed, hyperexpression of RNASET2 is able to control tumorigenesis by recruiting macrophages (mostly of the anticancer M1 subtype) at the tumor sites. We present biological data obtained by RNASET2 silencing in the poorly tumorigenetic and highly RNASET2-expressing human OVCAR3 cell line. RNASET2 knockdown was shown to stimulate in vivo tumor growth early after microinjection of OVCAR3 cells in nude mice. Moreover, we have investigated by molecular profiling the in vivo expression signature of human and mouse cell xenografts and disclosed the activation of pathways related to activation of the innate immune response and modulation of ECM components. Finally, we provide evidence for a role of RNASET2 in triggering an in vitro chemotactic response in macrophages. These results further highlight the critical role played by the microenvironment in RNASET2-mediated ovarian tumor suppression, which could eventually contribute to better clarify the pathogenesis of this disease.
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154
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Liu Y, Chen G, Lu L, Sun H, Guo Q, Xue K, Fan Y, Ding Z. RNASET2 in human spermatozoa and seminal plasma: a novel relevant indicator for asthenozoospermia. Andrology 2012; 1:75-84. [DOI: 10.1111/j.2047-2927.2012.00022.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 08/21/2012] [Accepted: 09/04/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Y. Liu
- Department of Histology and Embryology; School of Medicine; Shanghai Key Laboratory for Reproductive Medicine; Shanghai Jiao Tong University; Shanghai; China
| | - G. Chen
- Shanghai Jiai Genetics and IVF Institute-China USA Center; Shanghai; China
| | - L. Lu
- Shanghai Institute of Immunology; Shanghai; China
| | - H. Sun
- Department of Biochemistry and Molecular Cell Biology; School of Medicine; Shanghai Jiao Tong University; Shanghai; China
| | - Q. Guo
- Department of Histology and Embryology; School of Medicine; Shanghai Key Laboratory for Reproductive Medicine; Shanghai Jiao Tong University; Shanghai; China
| | - K. Xue
- Department of Histology and Embryology; School of Medicine; Shanghai Key Laboratory for Reproductive Medicine; Shanghai Jiao Tong University; Shanghai; China
| | - Y. Fan
- Department of Histology and Embryology; School of Medicine; Shanghai Key Laboratory for Reproductive Medicine; Shanghai Jiao Tong University; Shanghai; China
| | - Z. Ding
- Department of Histology and Embryology; School of Medicine; Shanghai Key Laboratory for Reproductive Medicine; Shanghai Jiao Tong University; Shanghai; China
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155
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Krey T, Bontems F, Vonrhein C, Vaney MC, Bricogne G, Rümenapf T, Rey FA. Crystal structure of the pestivirus envelope glycoprotein E(rns) and mechanistic analysis of its ribonuclease activity. Structure 2012; 20:862-73. [PMID: 22579253 DOI: 10.1016/j.str.2012.03.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 02/29/2012] [Accepted: 03/03/2012] [Indexed: 01/24/2023]
Abstract
Pestiviruses, which belong to the Flaviviridae family of RNA viruses, are important agents of veterinary diseases causing substantial economical losses in animal farming worldwide. Pestivirus particles display three envelope glycoproteins at their surface: E(rns), E1, and E2. We report here the crystal structure of the catalytic domain of E(rns), the ribonucleolytic activity of which is believed to counteract the innate immunity of the host. The structure reveals a three-dimensional fold corresponding to T2 ribonucleases from plants and fungi. Cocrystallization experiments with mono- and oligonucleotides revealed the structural basis for substrate recognition at two binding sites previously identified for T2 RNases. A detailed analysis of poly-U cleavage products using (31)P-NMR and size exclusion chromatography, together with molecular docking studies, provides a comprehensive mechanistic picture of E(rns) activity on its substrates and reveals the presence of at least one additional nucleotide binding site.
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Affiliation(s)
- Thomas Krey
- Unité de Virologie Structurale, Institut Pasteur, 75015 Paris, France.
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156
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Roldán JA, Rojas HJ, Goldraij A. Disorganization of F-actin cytoskeleton precedes vacuolar disruption in pollen tubes during the in vivo self-incompatibility response in Nicotiana alata. ANNALS OF BOTANY 2012; 110:787-95. [PMID: 22782242 PMCID: PMC3423811 DOI: 10.1093/aob/mcs153] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 05/03/2012] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS The integrity of actin filaments (F-actin) is essential for pollen-tube growth. In S-RNase-based self-incompatibility (SI), incompatible pollen tubes are inhibited in the style. Consequently, research efforts have focused on the alterations of pollen F-actin cytoskeleton during the SI response. However, so far, these studies were carried out in in vitro-grown pollen tubes. This study aimed to assess the timing of in vivo changes of pollen F-actin cytoskeleton taking place after compatible and incompatible pollinations in Nicotiana alata. To our knowledge, this is the first report of the in vivo F-actin alterations occurring during pollen rejection in the S-RNase-based SI system. METHODS The F-actin cytoskeleton and the vacuolar endomembrane system were fluorescently labelled in compatibly and incompatibly pollinated pistils at different times after pollination. The alterations induced by the SI reaction in pollen tubes were visualized by confocal laser scanning microscopy. KEY RESULTS Early after pollination, about 70 % of both compatible and incompatible pollen tubes showed an organized pattern of F-actin cables along the main axis of the cell. While in compatible pollinations this percentage was unchanged until pollen tubes reached the ovary, pollen tubes of incompatible pollinations underwent gradual and progressive F-actin disorganization. Colocalization of the F-actin cytoskeleton and the vacuolar endomembrane system, where S-RNases are compartmentalized, revealed that by day 6 after incompatible pollination, when the pollen-tube growth was already arrested, about 80 % of pollen tubes showed disrupted F-actin but a similar percentage had intact vacuolar compartments. CONCLUSIONS The results indicate that during the SI response in Nicotiana, disruption of the F-actin cytoskeleton precedes vacuolar membrane breakdown. Thus, incompatible pollen tubes undergo a sequential disorganization process of major subcellular structures. Results also suggest that the large pool of S-RNases released from vacuoles acts late in pollen rejection, after significant subcellular changes in incompatible pollen tubes.
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Affiliation(s)
| | | | - Ariel Goldraij
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC–CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, X5000HUA, Córdoba, Argentina
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157
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Structure-function analysis of Rny1 in tRNA cleavage and growth inhibition. PLoS One 2012; 7:e41111. [PMID: 22829915 PMCID: PMC3400635 DOI: 10.1371/journal.pone.0041111] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 06/18/2012] [Indexed: 01/05/2023] Open
Abstract
T2 ribonucleases are conserved nucleases that affect a variety of processes in eukaryotic cells including the regulation of self-incompatibility by S-RNases in plants, modulation of host immune cell responses by viral and schistosome T2 enzymes, and neurological development and tumor progression in humans. These roles for RNaseT2’s can be due to catalytic or catalytic-independent functions of the molecule. Despite this broad importance, the features of RNaseT2 proteins that modulate catalytic and catalytic-independent functions are poorly understood. Herein, we analyze the features of Rny1 in Saccharomyces cerevisiae to determine the requirements for cleaving tRNA in vivo and for inhibiting cellular growth in a catalytic-independent manner. We demonstrate that catalytic-independent inhibition of growth is a combinatorial property of the protein and is affected by a fungal-specific C-terminal extension, the conserved catalytic core, and the presence of a signal peptide. Catalytic functions of Rny1 are independent of the C-terminal extension, are affected by many mutations in the catalytic core, and also require a signal peptide. Biochemical flotation assays reveal that in rny1Δ cells, some tRNA molecules associate with membranes suggesting that cleavage of tRNAs by Rny1 can involve either tRNA association with, or uptake into, membrane compartments.
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158
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Thorn A, Steinfeld R, Ziegenbein M, Grapp M, Hsiao HH, Urlaub H, Sheldrick GM, Gärtner J, Krätzner R. Structure and activity of the only human RNase T2. Nucleic Acids Res 2012; 40:8733-42. [PMID: 22735700 PMCID: PMC3458558 DOI: 10.1093/nar/gks614] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in the gene of human RNase T2 are associated with white matter disease of the human brain. Although brain abnormalities (bilateral temporal lobe cysts and multifocal white matter lesions) and clinical symptoms (psychomotor impairments, spasticity and epilepsy) are well characterized, the pathomechanism of RNase T2 deficiency remains unclear. RNase T2 is the only member of the Rh/T2/S family of acidic hydrolases in humans. In recent years, new functions such as tumor suppressing properties of RNase T2 have been reported that are independent of its catalytic activity. We determined the X-ray structure of human RNase T2 at 1.6 Å resolution. The α+β core fold shows high similarity to those of known T2 RNase structures from plants, while, in contrast, the external loop regions show distinct structural differences. The catalytic features of RNase T2 in presence of bivalent cations were analyzed and the structural consequences of known clinical mutations were investigated. Our data provide further insight into the function of human RNase T2 and may prove useful in understanding its mode of action independent of its enzymatic activity.
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Affiliation(s)
- Andrea Thorn
- Department of Structural Chemistry, University of Göttingen, 37075 Göttingen, Germany
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159
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RNASET2--an autoantigen in anaplastic large cell lymphoma identified by protein array analysis. J Proteomics 2012; 75:5279-92. [PMID: 22732457 DOI: 10.1016/j.jprot.2012.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 06/07/2012] [Accepted: 06/11/2012] [Indexed: 02/01/2023]
Abstract
Characterising tumour-associated antigens (TAAs) not only represents an important approach to the identification of new diagnostic/prognostic markers, but can also provide information on disease processes and additional potential therapeutic targets. Preliminary screening of a protein macroarray, containing more than 12,000 different proteins, with sera from anaplastic lymphoma kinase (ALK)-negative and ALK-positive anaplastic large cell lymphoma (ALCL) patients identified ribonuclease and tumour suppressor protein Ribonuclease T2 (RNASET2), phosphatase lipid phosphate phosphatase-related protein type 3 (LPPR3) and apoptotic adaptor molecule Fas-associating protein (FADD) as ALK-negative ALCL-associated TAAs. Further validation of these observations was confirmed using the ALCL sera in reverse ELISAs. The circulating anti-RNASET2 autoantibodies present in ALCL patients' sera also recognised eukaryotically expressed RNASET2 protein. RNASET2 expression was then investigated in normal tissues and in lymphomas to explore its clinical potential. RNASET2 protein and mRNA levels showed highest expression in the spleen, leucocytes and pancreas. RNASET2 protein expression was not restricted to ALK-negative ALCL (81%), being expressed in ALK-positive ALCL (65%) as well as in a number of other lymphomas. The immunological recognition of RNASET2, its expression in ALCL and other lymphomas together with its known tumourigenic properties suggest that further studies on this autoantigen are warranted.
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160
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Wenzke KE, Cantemir-Stone C, Zhang J, Marsh CB, Huang K. Identifying common genes and networks in multi-organ fibrosis. AMIA JOINT SUMMITS ON TRANSLATIONAL SCIENCE PROCEEDINGS. AMIA JOINT SUMMITS ON TRANSLATIONAL SCIENCE 2012; 2012:106-15. [PMID: 22779061 PMCID: PMC3392050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/30/2022]
Abstract
UNLABELLED Fibroproliferative diseases of organs are poorly understood and generally lack effective anti-fibrotic treatments. Our goal was to identify the key regulatory factors in pathologic fibrosis, common between organ-based fibrotic disease. We analyzed 9 microarray datasets publicly available in the GEO datasets from lung, heart, liver and kidney fibrotic disease tissue (489 microarrays total, disease and control). We identified a set of 90 genes differentially expressed in at least five microarray datasets. We used IPA and DAVID analysis to identify gene networks and their molecular functions. A mutual information based network work activity analysis showed that a connective tissue disorders network was the most active for all types of fibrosis included in this analysis. CONCLUSION Our analysis indicates that despite different disease manifestation, organ fibrosis share a specific set of genes suggesting the potential for a common origin.
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Affiliation(s)
- Kevin E Wenzke
- Department of Biomedical Informatics, The Ohio State University, Columbus, OH
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161
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Kiritsi MN, Fragoulis EG, Sideris DC. Essential cysteine residues for human RNase κ catalytic activity. FEBS J 2012; 279:1318-26. [DOI: 10.1111/j.1742-4658.2012.08526.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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162
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de Leeuw M, González A, Lanir A, Roiz L, Smirnoff P, Schwartz B, Shoseyov O, Almog O. The 1.8 Å Crystal Structure of ACTIBIND Suggests a Mode of Action for T2 Ribonucleases As Antitumorigenic Agents. J Med Chem 2012; 55:1013-20. [DOI: 10.1021/jm1015507] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marina de Leeuw
- Department of Clinical Biochemistry,
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Ana González
- Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, MS 99, Menlo
Park, California 94025, United States
| | - Assaf Lanir
- Department of Clinical Biochemistry,
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
| | | | | | | | | | - Orna Almog
- Department of Clinical Biochemistry,
Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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163
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Matsumoto D, Tao R. Isolation of Pollen-expressed Actin as a Candidate Protein Interacting with S-RNase in Prunus avium L. ACTA ACUST UNITED AC 2012. [DOI: 10.2503/jjshs1.81.41] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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164
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Specific inhibition of bacterial RNase T2 by helix 41 of 16S ribosomal RNA. Nat Commun 2011; 2:549. [PMID: 22109523 DOI: 10.1038/ncomms1553] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Accepted: 10/19/2011] [Indexed: 11/08/2022] Open
Abstract
Ribonuclease (RNase) T2 is involved in scavenging exogenous RNAs in the periplasmic space of bacteria. In Escherichia coli, although the 30S ribosomal subunit has long been known as a specific inhibitor of RNase T2 (designated as RNase I in E. coli), both the biochemical mechanisms and physiological roles of this interaction remain to be elucidated. Here we show, by creating hybrid ribosomes and mutational studies, that helix 41 (h41) of the E. coli 16S ribosomal RNA has a crucial role in the specific inhibition of RNase I. Notably, h41-mutant strains exhibit a lower survival rate at stationary phase and severe cell lysis when the post-segregation killing protein SrnB is expressed. These phenotypic defects accompany significant RNA degradation caused by RNase I. Thus, h41 in 16S rRNA provides a physiological benefit for the host cells in coping with the potential cytotoxicity of RNase T2.
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165
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Acquati F, Monti L, Lualdi M, Fabbri M, Sacco MG, Gribaldo L, Taramelli R. Molecular signature induced by RNASET2, a tumor antagonizing gene, in ovarian cancer cells. Oncotarget 2011; 2:477-84. [PMID: 21646684 PMCID: PMC3248199 DOI: 10.18632/oncotarget.274] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Using the Hey3Met2 human ovarian cancer cell line, we previously found the RNASET2 gene to possess a remarkable in vivo tumor suppressor activity, although no in vitro features such as inhibition of cell proliferation, clonogenic potential, impaired growth in soft agar and increase in apoptotic rate could be detected. This is reminiscent of the behavior of genes belonging to the class of tumor antagonizing genes (TAG) which act mainly within the context of the microenvironment. Here we present transcriptional profiles analysis which indicates that investigations of the mechanisms of TAG biological functions require a comparison between the in vitro and in vivo expression patterns. Indeed several genes displaying a biological function potentially related to tumor suppression could not be validated by subsequent in vivo expression analysis. On the other hand the fact that we could find congruency for three genes both in vivo and in vitro adds a warning to a too much stringent categorization of this class of genes which relies on the sensitivity of the methodological approaches.
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Affiliation(s)
- Francesco Acquati
- Dipartimento di Biotecnologie e Scienze Molecolari, Università degli Studi dell'Insubria, via JH Dunant 3, 21100 Varese, Italy.
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166
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Andersen KL, Collins K. Several RNase T2 enzymes function in induced tRNA and rRNA turnover in the ciliate Tetrahymena. Mol Biol Cell 2011; 23:36-44. [PMID: 22049026 PMCID: PMC3248902 DOI: 10.1091/mbc.e11-08-0689] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
RNase T2 enzymes are produced by a wide range of organisms and have been implicated to function in diverse cellular processes, including stress-induced anticodon loop cleavage of mature tRNAs to generate tRNA halves. Here we describe a family of eight RNase T2 genes (RNT2A-RNT2H) in the ciliate Tetrahymena thermophila. We constructed strains lacking individual or combinations of these RNT2 genes that were viable but had distinct cellular and molecular phenotypes. In strains lacking only one Rnt2 protein or lacking a subfamily of three catalytically inactive Rnt2 proteins, starvation-induced tRNA fragments continued to accumulate, with only a minor change in fragment profile in one strain. We therefore generated strains lacking pairwise combinations of the top three candidates for Rnt2 tRNases. Each of these strains showed a distinct starvation-specific profile of tRNA and rRNA fragment accumulation. These results, the delineation of a broadened range of conditions that induce the accumulation of tRNA halves, and the demonstration of a predominantly ribonucleoprotein-free state of tRNA halves in cell extract suggest that ciliate tRNA halves are degradation intermediates in an autophagy pathway induced by growth arrest that functions to recycle idle protein synthesis machinery.
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Affiliation(s)
- Kasper L Andersen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
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167
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Abdulla MH, Lim KC, McKerrow JH, Caffrey CR. Proteomic identification of IPSE/alpha-1 as a major hepatotoxin secreted by Schistosoma mansoni eggs. PLoS Negl Trop Dis 2011; 5:e1368. [PMID: 22039561 PMCID: PMC3201919 DOI: 10.1371/journal.pntd.0001368] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 09/09/2011] [Indexed: 01/12/2023] Open
Abstract
Background Eggs deposited in the liver of the mammalian host by the blood fluke parasite, Schistosoma mansoni, normally drive a T-helper-2 (Th2)-mediated granulomatous response in immune-competent mice. By contrast, in mice deprived of T-cells and incapable of producing granulomata, egg-secreted proteins (ESP) induce acute hepatic injury and death. Previous work has shown that one such ESP, the T2 ribonuclease known as omega-1, is hepatotoxic in vivo in that specific antisera to omega-1 prevent hepatocyte damage. Methodology/Principal Findings Using an in vitro culture system employing mouse primary hepatocytes and alanine transaminase (ALT) activity as a marker of heptocyte injury, we demonstrated that S. mansoni eggs, egg-secreted proteins (ESP), soluble-egg antigen (SEA), and omega-1 are directly hepatotoxic and in a dose-dependent manner. Depletion of omega-1 using a monoclonal antibody abolished the toxicity of pure omega-1 and diminished the toxicity in ESP and SEA by 47 and 33%, respectively. Anion exchange chromatography of ESP yielded one predominant hepatotoxic fraction. Proteomics of that fraction identified the presence of IPSE/alpha-1 (IL-4 inducing principle from S. mansoni eggs), a known activator of basophils and inducer of Th2-type responses. Pure recombinant IPSE/alpha-1 also displayed a dose-dependent hepatotoxicity in vitro. Monoclonal antibody depletion of IPSE/alpha-1 abolished the latter's toxicity and diminished the total toxicity of ESP and SEA by 32 and 35%, respectively. Combined depletion of omega-1 and IPSE/alpha-1 diminished hepatotoxicity of ESP and SEA by 60 and 58% respectively. Conclusions We identified IPSE/alpha-1 as a novel hepatotoxin and conclude that both IPSE/alpha-1 and omega-1 account for the majority of the hepatotoxicity secreted by S. mansoni eggs. The flatworm disease, schistosomiasis, is a major public health problem in sub-Saharan Africa, South America and East Asia. A hallmark of infection with Schistosoma mansoni is the immune response to parasite eggs trapped in the liver and other organs. This response involves an infiltration of cells that surround the parasite egg forming a “granuloma.” In mice deprived of T-cells, this granulomatous response is lacking, and toxic products released by eggs quickly cause liver damage and death. Thus the granulomata protect the host from toxic egg products. Only one hepatotoxic molecule, omega-1, has been described to date. We set out to identify other S. mansoni egg hepatotoxins using liver cells grown in culture. We first showed that live eggs, their secretions, and pure omega-1 are toxic. Using a physical separation technique to prepare fractions from whole egg secretions, we identified the presence of IPSE/alpha-1, a protein that is known to strongly influence the immune system. We showed that IPSE/alpha-1 is also hepatotoxic, and that toxicity of both omega-1 and IPSE/alpha-1 can be prevented by first mixing the proteins with specific neutralizing antibodies. Both proteins constitute the majority of hepatotoxicity released by eggs.
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Affiliation(s)
- Maha-Hamadien Abdulla
- The Colorectal Research Center, Department of Surgery, King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia.
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168
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Dickson AM, Wilusz J. Strategies for viral RNA stability: live long and prosper. Trends Genet 2011; 27:286-93. [PMID: 21640425 PMCID: PMC3123725 DOI: 10.1016/j.tig.2011.04.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 04/21/2011] [Accepted: 04/26/2011] [Indexed: 12/23/2022]
Abstract
Eukaryotic cells have a powerful RNA decay machinery that plays an important and diverse role in regulating both the quantity and the quality of gene expression. Viral RNAs need to successfully navigate around this cellular machinery to initiate and maintain a highly productive infection. Recent work has shown that viruses have developed a variety of strategies to accomplish this, including inherent RNA shields, hijacking host RNA stability factors, incapacitating the host decay machinery and changing the entire landscape of RNA stability in cells using virally encoded nucleases. In addition to maintaining the stability of viral transcripts, these strategies can also contribute to the regulation and complexity of viral gene expression as well as to viral RNA evolution.
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Polakowski N, Han H, Lemasson I. Direct inhibition of RNAse T2 expression by the HTLV-1 viral protein Tax. Viruses 2011; 3:1485-500. [PMID: 21994792 PMCID: PMC3185805 DOI: 10.3390/v3081485] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 08/10/2011] [Indexed: 12/20/2022] Open
Abstract
Adult T-cell leukemia (ATL) is one of the primary diseases caused by Human T-cell Leukemia Virus type 1 (HTLV-1) infection. The virally-encoded Tax protein is believed to initiate early events in the development of this disease, as it is able to promote immortalization of T-cells and transformation of other cell types. These processes may be aided by the ability of the viral protein to directly deregulate expression of specific cellular genes through interactions with numerous transcriptional regulators. To identify gene promoters where Tax is localized, we isolated Tax-DNA complexes from an HTLV-1-infected T-cell line through a chromatin immunoprecipitation (ChIP) assay and used the DNA to probe a CpG island microarray. A site within the RNASET2 gene was found to be occupied by Tax. Real-time PCR analysis confirmed this result, and transient expression of Tax in uninfected cells led to the recruitment of the viral protein to the promoter. This event correlated with a decrease in the level of RNase T2 mRNA and protein, suggesting that Tax represses expression of this gene. Loss of RNase T2 expression occurs in certain hematological malignancies and other forms of cancer, and RNase T2 was recently reported to function as a tumor suppressor. Consequently, a reduction in the level of RNase T2 by Tax may play a role in ATL development.
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Affiliation(s)
- Nicholas Polakowski
- Authors to whom correspondence should be addressed; E-Mails: (N.P.); (I.L.); Tel.: +1-252-744-2711 or +1-252-744-2706; Fax: +1-252-744-3104
| | | | - Isabelle Lemasson
- Authors to whom correspondence should be addressed; E-Mails: (N.P.); (I.L.); Tel.: +1-252-744-2711 or +1-252-744-2706; Fax: +1-252-744-3104
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170
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Campomenosi P, Cinquetti R, Tallarita E, Lindqvist C, Raimondi I, Grassi P, Näsman J, Dell A, Haslam SM, Taramelli R, Acquati F. Comparison of the baculovirus-insect cell and Pichia pastoris heterologous systems for the expression of the human tumor suppressor protein RNASET2. Biotechnol Appl Biochem 2011; 58:39-49. [PMID: 21446958 DOI: 10.1002/bab.7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We report the expression of recombinant RNASET2, the only human member of the Rh/T2/S family of acid ribonucleases, in the yeast Pichia pastoris and the baculovirus-insect cell heterologous systems. In both models, the yield of recombinant protein was comparable and ranged between 5 mg/L (for a catalytically impaired mutant version of RNASET2) and 30 mg/L for the wild-type protein. Thus, the produced protein version rather than the expression system used appears to influence protein yield after optimization of culture conditions. The recombinant protein was found to undergo heterogeneous glycosylation in both systems, particularly in P. pastoris. Most importantly, the wild-type protein purified from both systems was found to be catalytically competent. The expression of recombinant RNASET2 in both systems will allow the implementation of functional assays in vivo and in vitro to better define the antioncogenic properties of this member of the Rh/T2/S ribonuclease family.
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Affiliation(s)
- Paola Campomenosi
- Department of Biotechnology and Molecular Sciences, University of Insubria, Varese, Italy.
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171
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Nowak MD, Davis AP, Anthony F, Yoder AD. Expression and trans-specific polymorphism of self-incompatibility RNases in coffea (Rubiaceae). PLoS One 2011; 6:e21019. [PMID: 21731641 PMCID: PMC3120821 DOI: 10.1371/journal.pone.0021019] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 05/17/2011] [Indexed: 12/20/2022] Open
Abstract
Self-incompatibility (SI) is widespread in the angiosperms, but identifying the biochemical components of SI mechanisms has proven to be difficult in most lineages. Coffea (coffee; Rubiaceae) is a genus of old-world tropical understory trees in which the vast majority of diploid species utilize a mechanism of gametophytic self-incompatibility (GSI). The S-RNase GSI system was one of the first SI mechanisms to be biochemically characterized, and likely represents the ancestral Eudicot condition as evidenced by its functional characterization in both asterid (Solanaceae, Plantaginaceae) and rosid (Rosaceae) lineages. The S-RNase GSI mechanism employs the activity of class III RNase T2 proteins to terminate the growth of "self" pollen tubes. Here, we investigate the mechanism of Coffea GSI and specifically examine the potential for homology to S-RNase GSI by sequencing class III RNase T2 genes in populations of 14 African and Madagascan Coffea species and the closely related self-compatible species Psilanthus ebracteolatus. Phylogenetic analyses of these sequences aligned to a diverse sample of plant RNase T2 genes show that the Coffea genome contains at least three class III RNase T2 genes. Patterns of tissue-specific gene expression identify one of these RNase T2 genes as the putative Coffea S-RNase gene. We show that populations of SI Coffea are remarkably polymorphic for putative S-RNase alleles, and exhibit a persistent pattern of trans-specific polymorphism characteristic of all S-RNase genes previously isolated from GSI Eudicot lineages. We thus conclude that Coffea GSI is most likely homologous to the classic Eudicot S-RNase system, which was retained since the divergence of the Rubiaceae lineage from an ancient SI Eudicot ancestor, nearly 90 million years ago.
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Affiliation(s)
- Michael D Nowak
- Department of Biology, Duke University, Durham, North Carolina, United States of America.
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172
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rnaset2 mutant zebrafish model familial cystic leukoencephalopathy and reveal a role for RNase T2 in degrading ribosomal RNA. Proc Natl Acad Sci U S A 2011; 108:1099-103. [PMID: 21199949 DOI: 10.1073/pnas.1009811107] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
T2-family acidic endoribonucleases are represented in all genomes. A physiological role for RNase T2 has yet to be defined for metazoa. RNASET2 mutation in humans is linked with a leukoencephalopathy that arises in infancy characterized by cortical cysts and multifocal white matter lesions. We now show localization of RNASET2 within lysosomes. Further, we demonstrate that loss of rnaset2 in mutant zebrafish results in accumulation of undigested rRNA within lysosomes within neurons of the brain. Further, by using high field intensity magnetic resonance microimaging, we reveal white matter lesions in these animals comparable to those observed in RNASET2-deficient infants. This correlates with accumulation of Amyloid precursor protein and astrocytes at sites of neurodegeneration. Thus we conclude that familial cystic leukoencephalopathy is a lysosomal storage disorder in which rRNA is the best candidate for the noxious storage material.
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173
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Extracellular poly (A) specific ribonuclease from Aspergillus niger ATCC 26550: Purification, biochemical, and spectroscopic studies. Process Biochem 2011. [DOI: 10.1016/j.procbio.2010.07.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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174
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Abstract
The overwhelming majority of RNase activity is engaged in catabolic processes. Viruses have no metabolism of their own, but rely completely on host cellular energy and substrate provision to support the biochemical processes necessary for virus replication. It is therefore obvious that RNA hydrolysis does not represent an obligate step in the viral life cycle that would have to be governed by viral proteins. Accordingly, RNases are found only rarely in the viral proteomes and serve special functions. In this chapter, several virus-specific RNases will be described and their role in the viral life cycle discussed. The text will concentrate on RNases of members of the nidoviruses, herpesviruses, pestiviruses, and several viruses with segmented negative-strand RNA genome including influenza virus. These enzymes are involved in specific steps of viral gene expression, viral genome replication, shutoff of host cellular gene expression, and interference with the host’s immune response to virus infection.
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175
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MacIntosh GC. RNase T2 Family: Enzymatic Properties, Functional Diversity, and Evolution of Ancient Ribonucleases. NUCLEIC ACIDS AND MOLECULAR BIOLOGY 2011. [DOI: 10.1007/978-3-642-21078-5_4] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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176
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Microenvironmental control of malignancy exerted by RNASET2, a widely conserved extracellular RNase. Proc Natl Acad Sci U S A 2010; 108:1104-9. [PMID: 21189302 DOI: 10.1073/pnas.1013746108] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
A recent body of evidence indicates an active role for stromal (mis)-regulation in the progression of neoplasias. Within this conceptual framework, genes belonging to the growing but still poorly characterized class of tumor antagonizing/malignancy suppressor genes (TAG/MSG) seem to play a crucial role in the regulation of the cross-talk between stromal and epithelial cells by controlling malignant growth in vivo without affecting any cancer-related phenotype in vitro. Here, we have functionally characterized the human RNASET2 gene, which encodes the first human member of the widespread Rh/T2/S family of extracellular RNases and was recently found to be down-regulated at the transcript level in several primary ovarian tumors or cell lines and in melanoma cell lines. Although we could not detect any activity for RNASET2 in several functional in vitro assays, a remarkable control of ovarian tumorigenesis could be detected in vivo. Moreover, the control of ovarian tumorigenesis mediated by this unique tumor suppressor gene occurs through modification of the cellular microenvironment and the induction of immunocompetent cells of the monocyte/macrophage lineage. Taken together, the data presented in this work strongly indicate RNASET2 as a previously unexplored member of the growing family of tumor-antagonizing genes.
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177
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The eight human "canonical" ribonucleases: molecular diversity, catalytic properties, and special biological actions of the enzyme proteins. FEBS Lett 2010; 584:2194-200. [PMID: 20388512 DOI: 10.1016/j.febslet.2010.04.018] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Revised: 04/07/2010] [Accepted: 04/07/2010] [Indexed: 01/25/2023]
Abstract
Human ribonucleases (RNases) are members of a large superfamily of rapidly evolving homologous proteins. Upon completion of the human genome, eight catalytically active RNases (numbered 1-8) were identified. These structurally distinct RNases, characterized by their various catalytic differences on different RNA substrates, constitute a gene family that appears to be the sole vertebrate-specific enzyme family. Apart from digestion of dietary RNA, a wide variety of biological actions, including neurotoxicity, angiogenesis, immunosuppressivity, and anti-pathogen activity, have been recently reported for almost all members of the family. Recent evolutionary studies suggest that RNases started off in vertebrates as host defence or angiogenic proteins.
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