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Szczepankiewicz AA, Parobczak K, Zaręba-Kozioł M, Ruszczycki B, Bijata M, Trzaskoma P, Hajnowski G, Holm-Kaczmarek D, Włodarczyk J, Sas-Nowosielska H, Wilczyński GM, Rędowicz MJ, Magalska A. Neuronal activation affects the organization and protein composition of the nuclear speckles. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119829. [PMID: 39197592 DOI: 10.1016/j.bbamcr.2024.119829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 08/06/2024] [Accepted: 08/20/2024] [Indexed: 09/01/2024]
Abstract
Nuclear speckles, also known as interchromatin granule clusters (IGCs), are subnuclear domains highly enriched in proteins involved in transcription and mRNA metabolism and, until recently, have been regarded primarily as their storage and modification hubs. However, several recent studies on non-neuronal cell types indicate that nuclear speckles may directly contribute to gene expression as some of the active genes have been shown to associate with these structures. Neuronal activity is one of the key transcriptional regulators and may lead to the rearrangement of some nuclear bodies. Notably, the impact of neuronal activation on IGC/nuclear speckles organization and function remains unexplored. To address this research gap, we examined whether and how neuronal stimulation affects the organization of these bodies in granular neurons from the rat hippocampal formation. Our findings demonstrate that neuronal stimulation induces morphological and proteomic remodelling of the nuclear speckles under both in vitro and in vivo conditions. Importantly, these changes are not associated with cellular stress or cell death but are dependent on transcription and splicing.
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Affiliation(s)
- Andrzej Antoni Szczepankiewicz
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Kamil Parobczak
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Monika Zaręba-Kozioł
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Błażej Ruszczycki
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland; AGH University of Krakow, Faculty of Physics and Applied Computer Science, Department of Medical Physics and Biophysics, al. A. Mickiewicza 30, 30-059 Krakow, Poland
| | - Monika Bijata
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Paweł Trzaskoma
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Grzegorz Hajnowski
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Dagmara Holm-Kaczmarek
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Jakub Włodarczyk
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Hanna Sas-Nowosielska
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology Polish Academy of Science, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Grzegorz Marek Wilczyński
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Maria Jolanta Rędowicz
- Laboratory of Molecular Basis of Cell Motility, Nencki Institute of Experimental Biology Polish Academy of Science, 3 Pasteur Street, 02-093 Warsaw, Poland
| | - Adriana Magalska
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur Street, 02-093 Warsaw, Poland.
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Wu Z, Li H, Zhao W, Zheng M, Cheng J, Cao Z, Sun C. Kidney toxicity and transcriptome analyses of male ICR mice acutely exposed to the mushroom toxin α-amanitin. Food Chem Toxicol 2024; 187:114622. [PMID: 38531469 DOI: 10.1016/j.fct.2024.114622] [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: 12/20/2023] [Revised: 03/20/2024] [Accepted: 03/22/2024] [Indexed: 03/28/2024]
Abstract
Amatoxins are responsible for most fatal mushroom poisoning cases, as it causes both hepatotoxicity and nephrotoxicity. However, studies on amatoxin nephrotoxicity are limited. Here, we investigated nephrotoxicity over 4 days and nephrotoxicity/hepatotoxicity over 14 days in mice. The organ weight ratio, serological indices, and tissue histology results indicated that a nephrotoxicity mouse model was established with two stages: (1) no apparent effects within 24 h; and (2) the appearance of adverse effects, with gradual worsening within 2-14 days. For each stage, the kidney transcriptome revealed patterns of differential mRNA expression and significant pathway changes, and Western blot analysis verified the expression of key proteins. Amanitin-induced nephrotoxicity was directly related to RNA polymerase II because mRNA levels decreased, RNA polymerase II-related pathways were significantly enriched at the transcription level, and RNA polymerase II protein was degraded in the early poisoning stage. In the late stage, nephrotoxicity was more severe than hepatotoxicity. This is likely associated with inflammation because inflammation-related pathways were significantly enriched and NF-κB activation was increased in the kidney.
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Affiliation(s)
- Zhijun Wu
- National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100050, China.
| | - Haijiao Li
- National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100050, China
| | - Wenjin Zhao
- National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100050, China
| | - Min Zheng
- National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100050, China
| | - Juan Cheng
- National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100050, China
| | - Zhengjie Cao
- National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100050, China
| | - Chengye Sun
- National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100050, China.
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A novel SNF2 ATPase complex in Trypanosoma brucei with a role in H2A.Z-mediated chromatin remodelling. PLoS Pathog 2022; 18:e1010514. [PMID: 35675371 PMCID: PMC9236257 DOI: 10.1371/journal.ppat.1010514] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 06/27/2022] [Accepted: 04/08/2022] [Indexed: 11/25/2022] Open
Abstract
A cascade of histone acetylation events with subsequent incorporation of a histone H2A variant plays an essential part in transcription regulation in various model organisms. A key player in this cascade is the chromatin remodelling complex SWR1, which replaces the canonical histone H2A with its variant H2A.Z. Transcriptional regulation of polycistronic transcription units in the unicellular parasite Trypanosoma brucei has been shown to be highly dependent on acetylation of H2A.Z, which is mediated by the histone-acetyltransferase HAT2. The chromatin remodelling complex which mediates H2A.Z incorporation is not known and an SWR1 orthologue in trypanosomes has not yet been reported. In this study, we identified and characterised an SWR1-like remodeller complex in T. brucei that is responsible for Pol II-dependent transcriptional regulation. Bioinformatic analysis of potential SNF2 DEAD/Box helicases, the key component of SWR1 complexes, identified a 1211 amino acids-long protein that exhibits key structural characteristics of the SWR1 subfamily. Systematic protein-protein interaction analysis revealed the existence of a novel complex exhibiting key features of an SWR1-like chromatin remodeller. RNAi-mediated depletion of the ATPase subunit of this complex resulted in a significant reduction of H2A.Z incorporation at transcription start sites and a subsequent decrease of steady-state mRNA levels. Furthermore, depletion of SWR1 and RNA-polymerase II (Pol II) caused massive chromatin condensation. The potential function of several proteins associated with the SWR1-like complex and with HAT2, the key factor of H2A.Z incorporation, is discussed. Trypanosoma brucei is the causative agent of African trypanosomiasis (sleeping sickness) in humans and nagana in cattle. Its unusual genomic organisation featuring large polycistronic units requires a general mechanism of transcription initiation, because individual gene promoters are mostly absent. Despite the fact that the histone variant H2A.Z has previously been identified as a key player of transcription regulation, the complex responsible for correct H2A.Z incorporation at transcription start sites (TSS) remains elusive. In other eukaryotes, SWR1, a SNF2 ATPase-associated chromatin remodelling complex, is responsible for correct incorporation of this histone variant. This study identified a SWR1-like complex in T. brucei. Depletion of the SNF2 ATPase resulted in a reduction of H2A.Z incorporation at the TSS and decreased steady-state mRNA levels accompanied by chromatin condensation. In addition to the SWR1-like complex, we also identified a trypanosome-specific HAT2 complex that includes the histone acetyltransferases HAT2, a key player in the H2A.Z incorporation process. This complex has a trypanosome-specific composition that is different from the NuA4/TIP60 complex in Saccharomyces cerevisiae.
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Wu Z, Li H, Zhang Y, Ding C, Zhao W, Dai J, Yu C, Yao Q, Zheng F, Fan J, Sun C. Liver transcriptome analyses of acute poisoning and recovery of male ICR mice exposed to the mushroom toxin α-amanitin. Arch Toxicol 2022; 96:1751-1766. [PMID: 35384471 DOI: 10.1007/s00204-022-03278-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 03/14/2022] [Indexed: 11/02/2022]
Abstract
Approximately 70-90% of mushroom poisoning deaths are caused by α-amanitin-induced liver injury resulting from RNA polymerase II (RNAP II) inhibition. Liver regeneration ability may contribute greatly to individual survival after α-amanitin poisoning. However, it is unclear what cellular pathways are activated to stimulate regeneration. We conducted dose-effect and time-effect studies in mice that were intraperitoneally injected with 0.33-0.66 mg/kg α-amanitin to establish a poisoning model. The liver/body weight ratio, serological indices, and pathology were evaluated to characterize the liver injury. In the time-effect study, the liver transcriptome was analyzed to explore the mRNA changes resulting from RNAP II inhibition and the underlying pathways associated with recovery. Based on the two animal studies, we established a poisoning model with three sequential liver states: early injury, regulation, and recovery. The mRNA changes reflected by the differentially expressed genes (DEGs) in the transcriptome could be used to illustrate the inhibition of RNAP II by α-amanitin. DEGs at four key time points were well matched with the three liver states, including 8-h downregulated genes in the early injury state, 16-h and 72-h upregulated genes in the regulation state, and 96-h upregulated/downregulated genes in the recovery state. By clustering analysis, the mTOR signaling pathway was screened out as the most promising potential pathway promoting recovery. The results of our investigations of the pathways and events downstream of the mTOR pathway indicated that the activation of mTOR probably contributes crucially to liver regeneration, which could be a promising basis for drug development.
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Affiliation(s)
- Zhijun Wu
- Chinese Center for Disease Control and Prevention, National Institute for Occupational Health and Poison Control, Beijing, 100050, China
| | - Haijiao Li
- Chinese Center for Disease Control and Prevention, National Institute for Occupational Health and Poison Control, Beijing, 100050, China
| | - Yizhe Zhang
- Chinese Center for Disease Control and Prevention, National Institute for Occupational Health and Poison Control, Beijing, 100050, China
| | - Chunguang Ding
- National Center for Occupational Safety and Health, Beijing, 202300, China
| | - Wenjin Zhao
- Chinese Center for Disease Control and Prevention, National Institute for Occupational Health and Poison Control, Beijing, 100050, China
| | - Jing Dai
- National Center for Occupational Safety and Health, Beijing, 202300, China
| | - Chengmin Yu
- The People's Hospital of Chuxiong Yi Autonomous Prefecture, Chuxiong, 675000, Yunnan, China
| | - Qunmei Yao
- The People's Hospital of Chuxiong Yi Autonomous Prefecture, Chuxiong, 675000, Yunnan, China
| | - Fenshuang Zheng
- The Emergency Department of the Affiliated Hospital of Yunnan University, Kunming, 650021, Yunnan, China
| | - Jingguang Fan
- National Center for Occupational Safety and Health, Beijing, 202300, China.
| | - Chengye Sun
- Chinese Center for Disease Control and Prevention, National Institute for Occupational Health and Poison Control, Beijing, 100050, China.
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Gilloteaux J, Bouchat J, Bielarz V, Brion JP, Nicaise C. A primary cilium in oligodendrocytes: a fine structure signal of repairs in thalamic Osmotic Demyelination Syndrome (ODS). Ultrastruct Pathol 2021; 45:128-157. [PMID: 34154511 DOI: 10.1080/01913123.2021.1891161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
A murine osmotic demyelination syndrome (ODS) model of the central nervous system included the relay thalamic ventral posterolateral (VPL) and ventral posteromedial (VPM) nuclei. Morphologic comparisons between treatments have revealed oligodendrocyte changes and, already 12 hours following the osmolality restoration, some heavily contrasted oligodendrocytes formed a unique intracellular primary cilium. This unique structure, found in vivo, in mature CNS oligodendrocytes, could account for a local awakening of some of the developmental proteome as it can be expressed in oligodendrocyte precursor cells. This resilience accompanied the emergence of arl13b protein expression along with restoration of nerve cell body axon hillocks shown in a previous issue of this journal. Additionally, the return of several thalamic oligodendrocyte fine features (nucleus, organelles) was shown 36 h later, including some mitosis. Those cell restorations and recognized translational activities comforted that local repairs could again take place, due to oligodendrocyte resilience after ODS instead or added to a postulated immigration of oligodendrocyte precursor cells distant from the sites of myelinolysis.
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Affiliation(s)
- Jacques Gilloteaux
- Unit of Research in Molecular Physiology (Urphym - NARILIS), Départment of Médecine, Université de Namur, Namur, Belgium.,Department of Anatomical Sciences, St George's University School of Medicine, KB Taylor Global Scholar's Program at UNN, School of Health and Life Sciences, Newcastle upon Tyne, UK
| | - Joanna Bouchat
- Unit of Research in Molecular Physiology (Urphym - NARILIS), Départment of Médecine, Université de Namur, Namur, Belgium
| | - Valery Bielarz
- Unit of Research in Molecular Physiology (Urphym - NARILIS), Départment of Médecine, Université de Namur, Namur, Belgium
| | - Jean-Pierre Brion
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculté de Médecine Université Libre de Bruxelles, Brussels, Belgium
| | - Charles Nicaise
- Unit of Research in Molecular Physiology (Urphym - NARILIS), Départment of Médecine, Université de Namur, Namur, Belgium
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Fiume L, Manerba M, Di Stefano G. Albumin-drug conjugates in the treatment of hepatic disorders. Expert Opin Drug Deliv 2014; 11:1203-17. [PMID: 24773257 DOI: 10.1517/17425247.2014.913567] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION This review deals with the use of serum albumin (SA) as a carrier for the selective delivery of drugs to liver cells. AREAS COVERED The synthesis and properties of the SA conjugates prepared to enhance the performance of the drugs used in the treatment of viral hepatitis, hepatocellular carcinoma (HCC), liver micrometastases and hepatic fibrosis are reported. EXPERT OPINION Studies in humans and laboratory animals demonstrated the capacity of SA conjugates to accomplish a liver targeting of the drugs, but at the same time underscored their limits and drawbacks, which can explain why to date these complexes did not reach a practical application. The major drawback is the need of administration by intravenous route, which prevents long-term daily treatments as required by some liver pathologies, such as chronic virus hepatitis and fibrosis. At present, only a conjugate carrying doxorubicin and addressed to the treatment of HCC showed in laboratory animals a solid potentiality to improve the value of the coupled drug. In the future, conjugation to SA could remain a successful strategy to permit the administration of drugs with rapid resolutive effects inside liver cells without causing severe extrahepatic adverse reactions.
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Affiliation(s)
- Luigi Fiume
- University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine , via San Giacomo 14 - 20126 Bologna , Italy +39 0512094700 ; +39 0512094746 ;
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Episkopou H, Kyrtopoulos SA, Sfikakis PP, Fousteri M, Dimopoulos MA, Mullenders LH, Souliotis VL. Association between Transcriptional Activity, Local Chromatin Structure, and the Efficiencies of Both Subpathways of Nucleotide Excision Repair of Melphalan Adducts. Cancer Res 2009; 69:4424-33. [DOI: 10.1158/0008-5472.can-08-3489] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Söderström KO. Nucleolar fragmentation in the rat pachytene spermatocytes and the Sertoli cells caused by alpha-amanitin. Hereditas 2009; 94:171-7. [PMID: 7298350 DOI: 10.1111/j.1601-5223.1981.tb01750.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Decker K, Keppler D. Galactosamine hepatitis: key role of the nucleotide deficiency period in the pathogenesis of cell injury and cell death. Rev Physiol Biochem Pharmacol 2005:77-106. [PMID: 4375846 DOI: 10.1007/bfb0027661] [Citation(s) in RCA: 285] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Souliotis VL, Sfikakis PP, Anderson LM, Kyrtopoulos SA. Intra- and intercellular variations in the repair efficiency of O6-methylguanine, and their contribution to kinetic complexity. Mutat Res 2004; 568:155-70. [PMID: 15542103 DOI: 10.1016/j.mrfmmm.2004.07.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Revised: 07/28/2004] [Accepted: 07/28/2004] [Indexed: 05/01/2023]
Abstract
Following administration to rats of various doses of N-nitrosodimethylamine (NDMA), O(6)-methylguanine (O(6)-meG) was lost from the DNA of four tissues (liver, white blood cells, lymph nodes, bone marrow) over two, sharply demarcated phases with substantially differing repair rates. Repair during each phase followed approximately first-order kinetics in O(6)-meG, even after a high dose of NDMA which caused substantial depletion of O(6)-alkylguanine-DNA alkyltransferase (AGT), a suicide repair protein. This is compatible with rate-determining adduct repair being brought about by a distinct, minor pool of AGT molecules which is rapidly replenished by de novo AGT synthesis. Similar biphasic repair kinetics were also observed in HepG2 cells treated in vitro with NDMA. In this case, the first phase of repair was inhibited by alpha-amanitin, an inhibitor of RNA polymerase II-mediated transcription. However, no dependence on transcriptional activity was found when O(6)-meG repair in specific gene sequences with different transcriptional status in rat liver was examined, suggesting that the effects of alpha-amanitin in HepG2 cells did not reflect inhibition of preferential repair of transcribed sequences. Repair was also examined in rat liver hepatocytes and non-parenchymal cells separately after administration of NDMA at non-AGT depleting doses. Within each cell-population, the repair followed single phase, first-order kinetics, with adduct loss from AGT-rich hepatocytes being significantly faster than from the relatively AGT-deficient non-parenchymal cells. In conclusion, differences in the AGT content of different cell subpopulations in the liver (and probably in other tissues), as well as additional cellular factors affecting repair efficiency, appear to determine the observed variation in the kinetics of repair of O(6)-meG. The additional cellular factors involved appear not to be related to the transcriptional state of the sequences being repaired, but may reflect different states of chromatin condensation.
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Affiliation(s)
- Vassilis L Souliotis
- National Hellenic Research Foundation, Institute of Biological Research and Biotechnology, 48 Vassileos Constantinou Ave., Athens 11635, Greece.
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Bermbach U, Faulstich H. Epidermal growth factor labeled beta-amanitin-poly-L-ornithine: preparation and evidence for specific cytotoxicity. Biochemistry 1990; 29:6839-45. [PMID: 2397216 DOI: 10.1021/bi00481a012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Poly-L-ornithine with an average molecular weight of 32K was reacted with beta-amanitin hydroxysuccinimide ester to form an amide-linked toxin conjugate. Loading of the polymeric chain with amanitin was high, corresponding to up to 35% of the total weight. To this amatoxin vehicle we attached a targeting molecule, human recombinant leucine-21 epidermal growth factor (hrEGFL), via a disulfide-containing linker moiety. A typical average stoichiometry of the hrEGFL labeled toxin conjugate was (L-Orn)164(beta-amanitin)19(COC2H4SSC2H4CO-hrEGFL)2. The affinity for EGF receptors of hrEGFL bound in this conjugate was tested by using A 431 cells. The affinity was eight times lower than that of unsubstituted hrEGFL but regarded as high enough for studying specific toxicity effects with cells bearing EGF receptors. We found that beta-amanitin in the labeled conjugate was able to inhibit the growth of A 431 cells at a concentration of 28 nM, 80 times lower than for native beta-amanitin and 20 times lower than for poly-L-ornithine-bound beta-amanitin without the hrEGFL label. The approximately 20-fold enhancement of cytotoxicity suggests a specific internalization of the toxin conjugate mediated by the hormone label. This idea is supported by the fact that also in another transformed fibroblast cell line, with an increased though smaller number of EGF receptors than A 431 cells, the corresponding enhancement of cytotoxicity was demonstrable but less pronounced (7-fold). The hormone-mediated increase in cytotoxicity of EGF labeled poly-L-ornithine-beta-amanitin conjugates, combined with their moderate toxicity in the mouse, encourages further examination of such compounds in tumor model systems in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- U Bermbach
- Max-Planck-Institut für medizinische Forschung, Abteilung Physiologie, Heidelberg, West Germany
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Gómez-Lechón MJ, Montoya A, López P, Donato T, Larrauri A, Castell JV. The potential use of cultured hepatocytes in predicting the hepatotoxicity of xenobiotics. Xenobiotica 1988; 18:725-35. [PMID: 3420948 DOI: 10.3109/00498258809041711] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
1. A protocol is proposed for screening for hepatotoxicity of xenobiotics in vitro in which hepatocytes exposed to the compounds are evaluated for both cytotoxic and metabolic effects. Four established hepatotoxins have been studied. 2. alpha-Amanitin at 1.5 pg/mg cell protein inhibited RNA synthesis by 93% and reduced albumin synthesis to 56% of the control after 13 h treatment. 3. D-Galactosamine at 40 microM inhibited glycogen synthesis by 31%, glucuronidation of p-nitrophenol by 13% and albumin synthesis by 10%, and produced an increase in cytosolic enzyme leakage. 4. Thioacetamide decreased ureogenesis after 24 h of treatment at 230 microM (31% inhibition) and after 48 h at 2.3 microM (25% inhibition). 5. Ultrastructural alterations of hepatocytes were found after 48 h exposure to 1 mM acetaminophen and were preceded by extensive leakage of the enzymes GOT and LDH. Membrane damage was observed after 24 h exposure to 0.1 mM acetaminophen.
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Faulstich H, Kirchner K, Derenzini M. Strongly enhanced toxicity of the mushroom toxin alpha-amanitin by an amatoxin-specific Fab or monoclonal antibody. Toxicon 1988; 26:491-9. [PMID: 3188055 DOI: 10.1016/0041-0101(88)90188-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A monoclonal antibody, with high affinity against the mushroom toxin alpha-amanitin, was prepared. Administration of the Fab fragment of the monoclonal antibody to mice caused a 50-fold increase in alpha-amanitin toxicity. Electron micrographs showed normal appearance of hepatocytes but typical, amanitin-induced lesions in cells of the proximal convoluted tubules of the kidney. The pronounced nephrotoxicity is mainly explained by glomerular filtration and tubular reabsorption of the Fab-amatoxin complex and, to a lesser extent, of the immunoglobulin-amatoxin complex, which is still c. Twice as toxic as free alpha-amanitin. To our knowledge this is the first reported case where immunoglobulins or their fragments enhance rather than decrease the activity of a toxin. Accordingly, immunotherapy of Amanita mushroom poisoning in humans does not appear promising.
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Affiliation(s)
- H Faulstich
- Max-Planck-Institut für Medizinische Forschung, Heidelberg, F.R.G
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14
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Nicoloff H, Rieger R. Mutations in rDNA : 3. Modulatory action of α-amanitin on aberration induction in nucleolus organizer regions. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 1985; 70:178-184. [PMID: 24254177 DOI: 10.1007/bf00275319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/1984] [Accepted: 09/04/1984] [Indexed: 06/02/2023]
Abstract
The action of α-amanitin, an inhibitor of RNA synthesis, on the induction by hydroxyurea (HU) of chromosomal aberrations in nucleolus organizer regions of barley was studied. The data obtained show that α-amanitin can effectively modify aberration induction in rDNA. Administered before mutagen treatment or in combination with the mutagen, the toxin significantly decreased the HU-induced aberration frequencies in NORs. The data obtained provide further evidence that α-amanitin is an effective modulator of aberration induction in NORs either by interfering with RNA synthesis or by modifying chromatin structure.
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Affiliation(s)
- H Nicoloff
- Zentralinstitut für Genetik und Kulturpflanzenforschung, DDR-4325, Gatersleben, German Democratic Republic
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Magalhães MC, Magalhães MM. Effects of alpha-amanitin on the fine structure of adrenal fasciculata cells in the young rat. Tissue Cell 1985; 17:27-37. [PMID: 4002211 DOI: 10.1016/0040-8166(85)90013-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The administration of 0.2 micrograms/g/bw of alpha-amanitin to approximately 20 g rats provoked the following nuclear modifications in rat adrenal fasciculata cells at 60 min: chromatin condensation, nucleolar fragmentation, increase in the number of PCG and clumping of ICG in the center of the nucleus. At longer time intervals (2.5 and 4.5 hr) these alterations were more evident, but at 24 hr the nuclear structure was back to normal with the exception of a persistent increased number of PCG. After injection of 0.75 micrograms/g/bw and at 2.5 hr, there was pulverization of condensed chromatin, fragmentation and partial segregation of the nucleolus with increased density of the fibrillar component. Cytoplasmic alterations were severe including cap-shaped mitochondria with electron-dense matrix surrounding lipid droplets, reduced endoplasmic reticulum of vesicular type and clusters of microvesicles with dense content in the Golgi trans-area. At 24 hr, the nuclear and cytoplasmic morphology returned to normal. These findings are interpreted as the morphological counterpart of a disturbance of extranucleolar and nucleolar RNA synthesis, as well as of lipid and lipoprotein metabolism, brought about by the drug.
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Abstract
Several potent and selective antiviral agents against herpes virus infections have been developed. However, the majority of compounds against other viral diseases has not yet reached such high standard. Based on progress in molecular virology it can, however, be anticipated that similar concepts of selective inhibition will also be developed for other virus groups. In addition to virus-induced enzymes, viral proteins other than enzymes with specific activities will be identified. The identification of active sites will lead to the design of new and specific inhibitors. Moreover, studies on the mode of action of the huge number of known antiviral compounds may provide the basis for new and potent approaches to specific virus chemotherapy. New inhibitors of viral replication may also be derived from 2'-5'A and other mediators of the interferon induced antiviral state. However, since 2'-5'A does not enter cells, is rapidly degraded by phosphodiesterases, and affects viral and cellular protein synthesis, only analogs which do not have these disadvantages may qualify as antiviral drugs. In addition to refinements at the molecular level quantitative assays for a better evaluation of antiviral agents for clinical use are required. For clinical trials, rapid diagnosis, early initiation of treatment, and quantitative evaluation of the antiviral effects of a drug need to be developed. Moreover, new methods of drug delivery and/or drug targeting will improve potency and selectivity of antiviral compounds. Drug carriers have already successfully been used in cancer therapy (Poste and Fidler, 1981) they should be also applicable to virus chemotherapy. Finally, a better understanding of the pathogenesis and the natural course of viral diseases will contribute to the development of more effective and safe antiviral agents.
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Abstract
Side effects of antiviral drugs might be circumvented by their selective delivery into infected cells. This targeting can be obtained by conjugation of the drugs to macromolecules which are taken up specifically by the infected cells. The experiments reviewed, on this approach to antiviral chemotherapy, are mainly directed at improving the chemotherapeutic index of adenine arabinoside (ara-A) in the treatment of chronic hepatitis B by its coupling to galactosyl terminating glycoproteins.
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Magalhães MC, Magalhães MM. Effects of thyroidectomy on the adrenal cortex zona fasciculata. JOURNAL OF ULTRASTRUCTURE RESEARCH 1981; 76:120-126. [PMID: 7299893 DOI: 10.1016/s0022-5320(81)80010-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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20
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Abstract
The acute toxic effects of phalloidin, a toxin from the green deathcup, Amanita phalloides, were tested in dogs. No fatalities occurred following intravenous injection; however, the biochemical parameters GPT, GOT, alkaline phosphatase, and total bilirubin yielded pathological values. Histologically the liver parenchyma revealed hemorrhagic necrosis and peliosis-like changes with penetration of red blood cells into hepatocytes.
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21
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Fakan S, Puvion E. The ultrastructural visualization of nucleolar and extranucleolar RNA synthesis and distribution. INTERNATIONAL REVIEW OF CYTOLOGY 1980; 65:255-99. [PMID: 6156137 DOI: 10.1016/s0074-7696(08)61962-2] [Citation(s) in RCA: 256] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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22
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Derenzini M. Fine structure of chromatin as visualized in thin sections with the Gautier selective stain for DNA. JOURNAL OF ULTRASTRUCTURE RESEARCH 1979; 69:239-48. [PMID: 90735 DOI: 10.1016/s0022-5320(79)90113-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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23
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Derenzini M, Pession-Brizzi A, Bonetti E, Novello F. Relationship between ultrastructure and function of hepatocyte chromatin: a study with adrenalectomized rats after cortisol administration. JOURNAL OF ULTRASTRUCTURE RESEARCH 1979; 67:161-79. [PMID: 89202 DOI: 10.1016/s0022-5320(79)80005-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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24
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Wieland T, Faulstich H. Amatoxins, phallotoxins, phallolysin, and antamanide: the biologically active components of poisonous Amanita mushrooms. CRC CRITICAL REVIEWS IN BIOCHEMISTRY 1978; 5:185-260. [PMID: 363352 DOI: 10.3109/10409237809149870] [Citation(s) in RCA: 331] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This review gives a comprehensive account of the molecular toxicology of the bicyclic peptides obtained from the poisonous mushrooms of the genus Amanita. The discussion of the biochemical events will be preceded by a consideration of the chemistry of the toxic peptides. The structural features essential for biological activities of both the amatoxins and the phallotoxins will be discussed, also including the most important analytical data. Similar consideration will be given to antamanide, a cyclic peptide, which counteracts phalloidin. In addition, the phallolysins, three cytolytic proteins from Amanita phalloides will be discussed. The report on the biological activity of the amatoxins will deal with the sensitivity of the different RNA-polymerases towards the toxins and with their action on various cell types. Consideration will also be given to systems in which alpha-amanitin was used and can be used as a molecular tool; in the past, many investigators used the inhibitor in molecular biology, genetics, and even in physiological research. As for the phallotoxins, discussion of the affinity of these toxins for actin is provied. Further discussion attempts to understand the course of intoxication by filling in the gap between the first molecular event, formation of microfilaments, and the various lesions in hepatocytes during the intoxication.
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25
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Derenzini M, Betts CM, Busi C, Fiume L. Ultrastructural changes in beta-cells of pancreatic islets in alpha-amanitin-poisoned mice. VIRCHOWS ARCHIV. B, CELL PATHOLOGY 1978; 28:13-20. [PMID: 97854 DOI: 10.1007/bf02889052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In mice poisoned by alpha-amanitin nuclear changes typical of this toxin were observed in beta-cells of pancreatic islets. The lesions became progressively more severe and at 48 h after toxin injection some cells were necrotic. The damage to these cells could have implications in the changes in glycogen metabolism which occur after alpha-aminitin poisoning.
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26
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Brasch K, Sinclair GD. The organization, composition and matrix of hepatocyte nuclei exposed to alpha-amanitin. VIRCHOWS ARCHIV. B, CELL PATHOLOGY 1978; 27:193-204. [PMID: 96580 DOI: 10.1007/bf02888994] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Alterations in the structure and molecular composition of avian hepatocyte nuclei were compared following administration in vivo of lethal and sub-lethal doses of alpha-amanitin. This toxin interferes with extranucleolar transcription by direct inhibition of RNA polymerase II activity. the resultant effects include: extensive condensation of chromatin, displacement of nucleoplasmic contents and fragmentation of nucleoli. Changes in nuclear morphology were quantitated by stereometry and related to variations in RNA and residual, non-histone proteins (NHP). Gross alterations in nuclear structure and depletion of RNA and NHP levels were of similar magnitude with both doses of amanitin. The effects were fully reversible, however, with a minimal dose but terminal with a lethal dose. DNA and histone protein levels remained unchanged at all stages. These results imply that the process of transciption may itself keep and/or maintain chromatin in a dispersed state, and that in the absence of transcription chromatin naturally condenses. Modification of nuclear proteins may be necessary only to maintain chromatin compacted permanently or for extended periods of time. A model of nuclear organization is proposed to incorporate these considerations and to identify the probable location of the nuclear matrix in situ.
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27
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Lindell TJ, O'Malley AF, Puglisi B. Inhibition of nucleoplasmic transcription and the translation of rapidly labeled nuclear proteins by low concentrations of actinomycin D in vivo. Proposed role of messenger RNA in ribosomal RNA transcription. Biochemistry 1978; 17:1154-60. [PMID: 656380 DOI: 10.1021/bi00600a003] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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28
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Derenzini M, Novello F, Pession-Brizzi A. Perichromatin fibrils and chromatin ultrastructural pattern. Exp Cell Res 1978; 112:443-54. [PMID: 631227 DOI: 10.1016/0014-4827(78)90226-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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29
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Connan G, Rabotti GF. Effects of alpha-amanitin on RNA synthesis in cultured chicken fibroblasts transformed by Rous sarcoma virus. Biochimie 1978; 60:85-90. [PMID: 206293 DOI: 10.1016/s0300-9084(78)80203-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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30
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Derenzini M, Moyne G. The nucleolar origin of certain perichromatin-like granules: a study with alpha-Amanitin. JOURNAL OF ULTRASTRUCTURE RESEARCH 1978; 62:213-9. [PMID: 650735 DOI: 10.1016/s0022-5320(78)80018-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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31
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Ghosh S, Paweletz N, Ghosh I. Cytological identification and characterization of the nuclear matrix. Exp Cell Res 1978; 111:363-71. [PMID: 75108 DOI: 10.1016/0014-4827(78)90181-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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32
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Sinclair GD, Brasch K. The reversible action of alpha-amanitin on nuclear structure and molecular composition. Exp Cell Res 1978; 111:1-14. [PMID: 620689 DOI: 10.1016/0014-4827(78)90230-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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33
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Hadjiolov AA, Nikolaev N. Maturation of ribosomal ribonucleic acids and the biogenesis of ribosomes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1978; 31:95-144. [PMID: 790469 DOI: 10.1016/0079-6107(78)90006-8] [Citation(s) in RCA: 115] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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34
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Vergleichende Untersuchungen der Kernveränderungen von Rattenhepatocyten nach Actinomycin D- und α-Amanitin-Vergiftung. ACTA ACUST UNITED AC 1977. [DOI: 10.1007/bf02889123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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35
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Romen W, Altmann HW. [The structure of the nucleolus during the inhibition of RNA-and protein synthesis (author's transl)]. KLINISCHE WOCHENSCHRIFT 1977; 55:563-7. [PMID: 328999 DOI: 10.1007/bf01490508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In cells treated with antimetabolites to inhibit RNA- and protein synthesis, electron microscopic studies reveal structural alterations of the nucleolus. The morphological appearance of the nucleolus differs depending of the inhibitor used. If transcription is prevented, segregation of nucleolar components is observed. Inhibition of processing of newly synthesized RNA results in a degranulation and an increase in the amount of nucleolar fibrils. A disturbance of the release of nucleolar ribonucleoproteins into the cytoplasm leads to an enlargement and a hypergranulation of the nucleolus. On the other hand interruption of translation of mRNAs has no immediate effect on the appearance of the nucleolar structure. Only after longer treatment of the cells with the translation inhibitor the nucleolus shrinks and becomes degranulated. The use of inhibitors with clearly defined mechanisms of action in a morphological study should make it possible to interpret similar nucleolar alterations seen in cancer cells and virus-infected cells on a molecular biological basis.
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36
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Derenzini M, Lorenzoni E, Marinozzi V, Barsotti P. Ultrastructural cytochemistry of active chromatin in regenerating rat hepatocytes. JOURNAL OF ULTRASTRUCTURE RESEARCH 1977; 59:250-62. [PMID: 68123 DOI: 10.1016/s0022-5320(77)90037-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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37
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Kallio A, Pösö H, Scalabrino G, Jänne J. Regulation of ornithine decarboxylase by diamines in regenerating rat liver. FEBS Lett 1977; 73:229-34. [PMID: 14027 DOI: 10.1016/0014-5793(77)80987-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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38
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Laval M, Bouteille M, Moulé Y. Effect of the ionic environment on the transcriptional activity of rat liver nucleoli. Exp Cell Res 1976; 102:365-75. [PMID: 976353 DOI: 10.1016/0014-4827(76)90052-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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39
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40
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Derenzini M, Novello F. RNA synthesis in alpha-amanitin-poisoned rats: prevention of recovery by inhibition of protein synthesis. EXPERIENTIA 1976; 32:1184-6. [PMID: 971757 DOI: 10.1007/bf01927616] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The treatment with cycloheximide of rats previously poisoned with alpha-amanitin hinders the recovery of RNA synthesis observed in the liver of rats treated with alpha-amanitin alone. The recovery of RNA synthesis can be ascribed to the capability of poisoned rats to synthesize new RNA-polymerase II.
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41
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Derenzini M, Marinozzi V, Novello F. Effects of alpha-amanitine on chromatin in regenerating rat hepatocytes: a biochemical and morphologic study. VIRCHOWS ARCHIV. B, CELL PATHOLOGY 1976; 20:307-18. [PMID: 820061 DOI: 10.1007/bf02890349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Almost all the chromatin in nuclei of regenerating rat liver hepatocytes 15 h and particularly 24 h after partial hepatectomy appeared as decondensed chromatin. Treatment with alpha-amanitine induced a clear condensation of decondensed chromatin as early as 30 min after toxin injection. The degree of condensation increased further until, 2 h after poisoning, almost all the chromatin was found to be in condensed form. Because the synthesis of DNA, after toxin injection, was not modified during the first 2h and 30 min, our results indicate that the chromatin condensation did not affect the synthesis of DNA. In the present paper the relationships between the inhibition of RNA synthesis and the chromatin ultrastructural changes are also discussed.
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42
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Baccino FM, Cantino D, Zuretti MF. Studies on the hepatotoxicity of Amanita phalloides in the rat. 1. Liver cell vacuolation. Exp Mol Pathol 1976; 24:159-75. [PMID: 770185 DOI: 10.1016/0014-4800(76)90003-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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43
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Bonetti E, Derenzini M, Fiume L. Increased penetration of amanitine into hepatocytes when conjugated with albumin. Arch Toxicol 1976; 35:69-73. [PMID: 946409 DOI: 10.1007/bf00333987] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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44
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Fong WF, Fuchs MS. The long term effect of α-amanitin on RNA synthesis in adult female Aedes aegypti. ACTA ACUST UNITED AC 1976. [DOI: 10.1016/0020-1790(76)90020-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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45
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Derenzini M, Bonetti E. Cycloheximide-induced ultrastructural changes in hepatocyte nuclei in partially hepatectomized rats. VIRCHOWS ARCHIV. B, CELL PATHOLOGY 1975; 19:115-25. [PMID: 810957 DOI: 10.1007/bf02889361] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Nearly all the chromatin in regenerating rat hepatocytes appears to decondensed form 24 h after partial hepatectomy. When cycloheximide (CXM) is administered to partially hepatectomized rats, a marked condensation of chromatin occurs; 4 h after administration the quantity of condensed chromatin present is much higher than that found in the hepatocytes of sham-operated, untreated rats. No segregation or fragmentation of the nucleolus were, however, observed; this shows that the condensation of chromatin is not by itself sufficient to induce the segregation and fragmentation of the nucleolus. The mechanism governing CMX-induced chromatin condensation in regenerating hepatocytes is discussed.
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46
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Singer II. Ultrastructural studies of H-1 parvovirus replication. II. Induced changes in the deoxyribonucleoprotein and ribonucleoprotein components of human NB cell nuclei. Exp Cell Res 1975; 95:205-17. [PMID: 1193148 DOI: 10.1016/0014-4827(75)90625-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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47
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Herzog J, Farber JL. Fibrillar nucleolar remnants do not contain macromolecular precursors of ribosomal RNA. Demonstration by the effects of d-galactosamine. Exp Cell Res 1975; 93:502-5. [PMID: 50951 DOI: 10.1016/0014-4827(75)90482-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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48
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Paaso B, Harrison DC. A new look at an old problem: mushroom poisoning. Clinical presentations and new therapeutic approaches. Am J Med 1975; 58:505-9. [PMID: 1124787 DOI: 10.1016/0002-9343(75)90123-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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49
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Scheer U, Trendelenburg F, Franke WW. Effects of actinomycin D on the association of newly formed ribonucleoproteins with the cistrons of ribosomal RNA in Triturus oocytes. J Cell Biol 1975; 65:163-79. [PMID: 1127008 PMCID: PMC2111160 DOI: 10.1083/jcb.65.1.163] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The effect of actinomycin D(AMD) on the association of the nascent ribonucleo-protein (RNP) fibrils containing the precursors of ribosomal RNA (pre-rRNA) with their template deoxyribonucleoprotein (rDNP) strands has been studied in lampbrush stage oocytes from Triturus alpestris. Ovary pieces were incubated in vitro either in media containing radioactive ribonucleosides and then, for various times, in solutions containing 25 mug/ml AMD, or were directly exposed to the drug. The ultrastructure of the nucleoli and the nuclear periphery was studied by electron microscopy of thin sections and positively stained spread preparations of isolated nuclear contents, and by light and electron microscope autoradiography. The fate of the labeled pre-rRNA was followed by gel electrophoresis of RNA extracted from manually isolated nuclei. Our results show that the growing fibrils which contain the nascent pre-rRNA progressively detach from the DNP strands, the majority being released between 45 and 180 min after application of the drug. The release pattern seems to be random and does not show preference for regions close to the initiator or terminator sites of the transcribed rDNP units. There is a pronounced tendency to removal of groups of adjacent mascent fibrils. The effect of the drug is very heterogeneous. Even after 3 h of treatment with AMD the nucleoli exhibit several individual transcriptional units which appear almost completely covered with lateral fibrils. Autoradiography revealed that most of this released RNP remains within the confinements of the nucleoli which show some foci of aggregation and condensation of fibrillar components but no clear "segregation" phenomenon. In the gel-electrophoretic analysis, a significant but moderate decrease of labeled pre-rRNA was noted only in the first stable pre-rRNA component, whereas pre-rRNA classes of lower molecular weight are very stable under these conditions. The results are discussed in relation to the stability of rDNA transcription complexes and as a basis for an explanation of the ultrastructural changes which are generally observed in nucleoli of AMD-treated cells. It is postulated that inhibition of transcription results in a slow but progressive release of the arrested incomplete RNP fibrils from the template.
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50
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Kedinger C, Simard R. The action of alpha-amanitin on RNA synthesis in Chinese hamster ovary cells. Ultrastructural and biochemical studies. J Cell Biol 1974; 63:831-42. [PMID: 4474178 PMCID: PMC2109362 DOI: 10.1083/jcb.63.3.831] [Citation(s) in RCA: 45] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
alpha-Amanitin acts in vitro as a selective inhibitor of the nucleoplasmic form B RNA polymerases. Treatment of Chinese hamster ovary (CHO) cells with this drug leads principally to a severe fragmentation of the nucleoli. While the ultrastructural lesions induced by alpha-amanitin in CHO cells and in rat or mouse liver are quite similar, the results diverge concerning the effect on RNA synthesis. It has been shown that in rat or mouse liver alpha-amanitin blocks both extranucleolar and nucleolar RNA synthesis. Our autoradiographic and biochemical evidence indicates that in CHO cells high molecular weight extranucleolar RNA synthesis (HnRNA) is blocked by the alpha-amanitin treatment, whereas nucleolar RNA (preribosomal RNA) synthesis remains unaffected even several hours after the inhibition of extranucleolar RNA synthesis. Furthermore, the processing of this RNA as well as its transport to the cytoplasm seem only slightly affected by the treatment. Finally, under these conditions, the synthesis of the low molecular RNA species (4-5S) still occurs, though less actively. The results are interpreted as evidence for a selective impairment of HnRNA synthesis by alpha-amanitin in CHO cells.
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