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Chiurillo MA, Carlson J, Bertolini MS, Raja A, Lander N. Dual localization of receptor-type adenylate cyclases and cAMP response protein 3 unveils the presence of two putative signaling microdomains in Trypanosoma cruzi. mBio 2023; 14:e0106423. [PMID: 37477489 PMCID: PMC10470820 DOI: 10.1128/mbio.01064-23] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 06/02/2023] [Indexed: 07/22/2023] Open
Abstract
Trypanosoma cruzi is the etiologic agent of Chagas disease, a leading cause of disability and premature death in the Americas. This parasite spends its life between a triatomine insect and a mammalian host, transitioning between developmental stages in response to microenvironmental changes. Among the second messengers driving differentiation in T. cruzi, cAMP has been shown to mediate metacyclogenesis and response to osmotic stress, but this signaling pathway remains largely unexplored in this parasite. Adenylate cyclases (ACs) catalyze the conversion of ATP to cAMP. They comprise a multigene family encoding putative receptor-type ACs in T. cruzi. Using protein sequence alignment, we classified them into five groups and chose a representative member from each group to study their localization (TcAC1-TcAC5). We expressed an HA-tagged version of each protein in T. cruzi and performed immunofluorescence analysis. A peculiar dual localization of TcAC1 and TcAC2 was observed in the flagellar distal domain and in the contractile vacuole complex (CVC), and their enzymatic activity was confirmed by gene complementation in yeast. Furthermore, TcAC1 overexpressing parasites showed an increased metacyclogenesis, a defect in host cell invasion, and a reduced intracellular replication, highlighting the importance of this protein throughout T. cruzi life cycle. These mutants were more tolerant to hypoosmotic stress and showed a higher adhesion capacity during in vitro metacyclogenesis, whereas the wild-type phenotype was restored after disrupting TcAC1 localization. Finally, TcAC1 was found to interact with cAMP response protein 3 (TcCARP3), co-localizing with this protein in the flagellar tip and CVC. IMPORTANCE We identified three components of the cAMP signaling pathway (TcAC1, TcAC2, and TcCARP3) with dual localization in Trypanosoma cruzi: the flagellar distal domain and the CVC, structures involved in cell adhesion and osmoregulation, respectively. We found evidence on the role of TcAC1 in both cellular processes, as well as in metacyclogenesis. Our data suggest that TcACs act as signal sensors and transducers through cAMP synthesis in membrane microdomains. We propose a model in which TcACs sense the harsh conditions in the triatomine hindgut (nutrient deprivation, acidic pH, osmotic stress, ionic composition, hydrophobic interactions) and become active. Synthesis of cAMP then triggers cell adhesion prior completion of metacyclogenesis, while mediating a response to osmotic stress in the parasite. These results shed light into the mechanisms driving cAMP-mediated cell differentiation in T. cruzi, while raising new questions on the activation of TcACs and the role of downstream components of this pathway.
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Affiliation(s)
- Miguel A. Chiurillo
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, USA
| | - Joshua Carlson
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, USA
| | - Mayara S. Bertolini
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, Georgia, USA
- Department of Cellular Biology, University of Georgia, Athens, Georgia, USA
| | - Aqsa Raja
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, USA
| | - Noelia Lander
- Department of Biological Sciences, University of Cincinnati, Cincinnati, Ohio, USA
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Chiurillo MA, Ahmed M, González C, Raja A, Lander N. Gene editing of putative cAMP and Ca 2+ -regulated proteins using an efficient cloning-free CRISPR/Cas9 system in Trypanosoma cruzi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.09.548290. [PMID: 37502958 PMCID: PMC10369910 DOI: 10.1101/2023.07.09.548290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Trypanosoma cruzi , the agent of Chagas disease, must adapt to a diversity of environmental conditions that it faces during its life cycle. The adaptation to these changes is mediated by signaling pathways that coordinate the cellular responses to the new environmental settings. Cyclic AMP (cAMP) and Calcium (Ca 2+ ) signaling pathways regulate critical cellular processes in this parasite, such as differentiation, osmoregulation, host cell invasion and cell bioenergetics. Although the use of CRISPR/Cas9 technology prompted reverse genetics approaches for functional analysis in T. cruzi , it is still necessary to expand the toolbox for genome editing in this parasite, as for example to perform multigene analysis. Here we used an efficient T7RNAP/Cas9 strategy to tag and delete three genes predicted to be involved in cAMP and Ca 2+ signaling pathways: a putative Ca 2+ /calmodulin-dependent protein kinase ( CAMK ), Flagellar Member 6 ( FLAM6 ) and Cyclic nucleotide-binding domain/C2 domain-containing protein ( CC2CP ). We endogenously tagged these three genes and determined the subcellular localization of the tagged proteins. Furthermore, the strategy used to knockout these genes allow us to presume that TcCC2CP is an essential gene in T. cruzi epimastigotes. Our results will open new venues for future research on the role of these proteins in T. cruzi .
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Abstract
Acidocalcisomes are electron-dense organelles rich in polyphosphate and inorganic and organic cations that are acidified by proton pumps, and possess several channels, pumps, and transporters. They are present in bacteria and eukaryotes and have been studied in greater detail in trypanosomatids. Biogenesis studies of trypanosomatid acidocalcisomes found that they share properties with lysosome-related organelles of animal cells. In addition to their described roles in autophagy, cation and phosphorus storage, osmoregulation, pH homeostasis, and pathogenesis, recent studies have defined the role of these organelles in phosphate utilization, calcium ion (Ca2+ ) signaling, and bioenergetics, and will be the main subject of this review.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | - Guozhong Huang
- Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
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4
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Xanthine Analogs Suppress Trypanosoma cruzi Infection In Vitro Using PDEs as Targets. MICROBIOLOGY RESEARCH 2022. [DOI: 10.3390/microbiolres13040052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Trypanosoma cruzi (T. cruzi), the causative agent of Chagas disease, has infected 6 million people, putting 70 million people at risk worldwide. Presently, very limited drugs are available, and these have severe side effects. Hence, there is an urgency to delve into other pathways and targets for novel drugs. Trypanosoma cruzi (T. cruzi) expresses a number of different cyclic AMP (cAMP)-specific phosphodiesterases (PDEs). cAMP is one of the key regulators of mammalian cell proliferation and differentiation, and it also plays an important role in T. cruzi growth. Very few studies have demonstrated the important role of cyclic nucleotide-specific PDEs in T. cruzi’s survival. T. cruzi phosphodiesterase C (TcrPDEC) has been proposed as a potential new drug target for treating Chagas disease. In the current study, we screen several analogs of xanthine for potency against trypomastigote and amastigote growth in vitro using three different strains of T. cruzi (Tulahuen, Y and CA-1/CL72). One of the potent analogs, GVK14, has been shown to inhibit all three strains of amastigotes in host cells as well as axenic cultures. In conclusion, xanthine analogs that inhibit T. cruzi PDE may provide novel alternative therapeutic options for Chagas disease.
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Zheng Y, Müller J, Kunz S, Siderius M, Maes L, Caljon G, Müller N, Hemphill A, Sterk GJ, Leurs R. 3-nitroimidazo[1,2-b]pyridazine as a novel scaffold for antiparasitics with sub-nanomolar anti-Giardia lamblia activity. Int J Parasitol Drugs Drug Resist 2022; 19:47-55. [PMID: 35716585 PMCID: PMC9213561 DOI: 10.1016/j.ijpddr.2022.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 11/26/2022]
Abstract
As there is a continuous need for novel anti-infectives, the present study aimed to fuse two modes of action into a novel 3-nitroimidazo[1,2-b]pyridazine scaffold to improve antiparasitic efficacy. For this purpose, we combined known structural elements of phosphodiesterase inhibitors, a target recently proposed for Trypanosoma brucei and Giardia lamblia, with a nitroimidazole scaffold to generate nitrosative stress. The compounds were evaluated in vitro against a panel of protozoal parasites, namely Giardia lamblia, Trypanosoma brucei, T. cruzi, Leishmania infantum and Plasmodium falciparum and for cytotoxicity on MRC-5 cells. Interestingly, selective sub-nanomolar activity was obtained against G. lamblia, and by testing several analogues with and without the nitro group, it was shown that the presence of a nitro group, but not PDE inhibition, is responsible for the low IC50 values of these novel compounds. Adding the favourable drug-like properties (low molecular weight, cLogP (1.2–4.1) and low polar surface area), the key compounds from the 3-nitroimidazo[1,2-b]pyridazine series can be considered as valuable hits for further anti-giardiasis drug exploration and development. Analogues fusing a nitroimidazole moiety and a PDE inhibitor scaffold were prepared. These compounds were tested in vitro against a panel of protozoal parasites. Against Giardia lamblia, sub-nanomolar IC50 values were determined. PDE inhibition provided no significant contribution to the anti-Giardia potency. High potency with drug-like properties warrants further study of this hit series.
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Llanos MA, Alberca LN, Larrea SCV, Schoijet AC, Alonso GD, Bellera CL, Gavenet L, Talevi A. Homology Modeling and Molecular Dynamics Simulations of Trypanosoma cruzi Phosphodiesterase b1. Chem Biodivers 2021; 19:e202100712. [PMID: 34813143 DOI: 10.1002/cbdv.202100712] [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: 08/31/2021] [Accepted: 11/22/2021] [Indexed: 11/07/2022]
Abstract
Cyclic nucleotide phosphodiesterases have been implicated in the proliferation, differentiation and osmotic regulation of trypanosomatids; in some trypanosomatid species, they have been validated as molecular targets for the development of new therapeutic agents. Because the experimental structure of Trypanosoma cruzi PDEb1 (TcrPDEb1) has not been solved so far, an homology model of the target was created using the structure of Trypanosoma brucei PDEb1 (TbrPDEb1) as a template. The model was refined by extensive enhanced sampling molecular dynamics simulations, and representative snapshots were extracted from the trajectory by combined clustering analysis. This structural ensemble was used to develop a structure-based docking model of the target. The docking accuracy of the model was validated by redocking and cross-docking experiments using all available crystal structures of TbrPDEb1, whereas the scoring accuracy was validated through a retrospective screen, using a carefully curated dataset of compounds assayed against TbrPDEb1 and/or TcrPDEb1. Considering the results from in silico validations, the model may be applied in prospective virtual screening campaigns to identify novel hits, as well as to guide the rational design of potent and selective inhibitors targeting this enzyme.
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Affiliation(s)
- Manuel A Llanos
- Laboratory of Bioactive Research and Development (LIDeB), Faculty of Exact Sciences, University of La Plata - 47 and 115, La Plata, Buenos Aires, Argentina
| | - Lucas N Alberca
- Laboratory of Bioactive Research and Development (LIDeB), Faculty of Exact Sciences, University of La Plata - 47 and 115, La Plata, Buenos Aires, Argentina
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
| | - Salomé C Vilchez Larrea
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
| | - Alejandra C Schoijet
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
| | - Guillermo D Alonso
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Buenos Aires, Argentina
| | - Carolina L Bellera
- Laboratory of Bioactive Research and Development (LIDeB), Faculty of Exact Sciences, University of La Plata - 47 and 115, La Plata, Buenos Aires, Argentina
- National Scientific and Technical Research Council (CONICET) - CCT, La Plata, Argentina
| | - Luciana Gavenet
- Laboratory of Bioactive Research and Development (LIDeB), Faculty of Exact Sciences, University of La Plata - 47 and 115, La Plata, Buenos Aires, Argentina
- National Scientific and Technical Research Council (CONICET) - CCT, La Plata, Argentina
| | - Alan Talevi
- Laboratory of Bioactive Research and Development (LIDeB), Faculty of Exact Sciences, University of La Plata - 47 and 115, La Plata, Buenos Aires, Argentina
- National Scientific and Technical Research Council (CONICET) - CCT, La Plata, Argentina
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7
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De Araújo JS, da Silva PB, Batista MM, Peres RB, Cardoso-Santos C, Kalejaiye TD, Munday JC, De Heuvel E, Sterk GJ, Augustyns K, Salado IG, Matheeussen A, De Esch I, De Koning HP, Leurs R, Maes L, Soeiro MDNC. Evaluation of phthalazinone phosphodiesterase inhibitors with improved activity and selectivity against Trypanosoma cruzi. J Antimicrob Chemother 2021; 75:958-967. [PMID: 31860098 DOI: 10.1093/jac/dkz516] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/15/2019] [Accepted: 11/08/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi, needs urgent alternative therapeutic options as the treatments currently available display severe limitations, mainly related to efficacy and toxicity. OBJECTIVES As phosphodiesterases (PDEs) have been claimed as novel targets against T. cruzi, our aim was to evaluate the biological aspects of 12 new phthalazinone PDE inhibitors against different T. cruzi strains and parasite forms relevant for human infection. METHODS In vitro trypanocidal activity of the inhibitors was assessed alone and in combination with benznidazole. Their effects on parasite ultrastructural and cAMP levels were determined. PDE mRNA levels from the different T. cruzi forms were measured by quantitative reverse transcription PCR. RESULTS Five TcrPDEs were found to be expressed in all parasite stages. Four compounds displayed strong effects against intracellular amastigotes. Against bloodstream trypomastigotes (BTs), three were at least as potent as benznidazole. In vitro combination therapy with one of the most active inhibitors on both parasite forms (NPD-040) plus benznidazole demonstrated a quite synergistic profile (xΣ FICI = 0.58) against intracellular amastigotes but no interaction (xΣ FICI = 1.27) when BTs were assayed. BTs treated with NPD-040 presented disrupted Golgi apparatus, a swollen flagellar pocket and signs of autophagy. cAMP measurements of untreated parasites showed that amastigotes have higher ability to efflux this second messenger than BTs. NPD-001 and NPD-040 increase the intracellular cAMP content in both BTs and amastigotes, which is also released into the extracellular milieu. CONCLUSIONS The findings demonstrate the potential of PDE inhibitors as anti-T. cruzi drug candidates.
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Affiliation(s)
| | | | - Marcos Meuser Batista
- Laboratório de Biologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Raiza Brandão Peres
- Laboratório de Biologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Camila Cardoso-Santos
- Laboratório de Biologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Titilola D Kalejaiye
- Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Jane C Munday
- Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Erik De Heuvel
- Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines & Systems, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Geert Jan Sterk
- Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines & Systems, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Koen Augustyns
- Laboratory of Medicinal Chemistry, University of Antwerp, Antwerp, Belgium
| | - Irene G Salado
- Laboratory of Medicinal Chemistry, University of Antwerp, Antwerp, Belgium
| | - An Matheeussen
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Antwerp, Belgium
| | - Iwan De Esch
- Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines & Systems, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Harry P De Koning
- Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
| | - Rob Leurs
- Medicinal Chemistry, Amsterdam Institute for Molecules, Medicines & Systems, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Louis Maes
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Antwerp, Belgium
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8
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Lander N, Chiurillo MA, Docampo R. Signaling pathways involved in environmental sensing in Trypanosoma cruzi. Mol Microbiol 2021; 115:819-828. [PMID: 33034088 PMCID: PMC8032824 DOI: 10.1111/mmi.14621] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/28/2020] [Accepted: 09/30/2020] [Indexed: 12/18/2022]
Abstract
Trypanosoma cruzi is a unicellular parasite and the etiologic agent of Chagas disease. The parasite has a digenetic life cycle alternating between mammalian and insect hosts, where it faces a variety of environmental conditions to which it must adapt in order to survive. The adaptation to these changes is mediated by signaling pathways that coordinate the cellular responses to the new environmental settings. Major environmental changes include temperature, nutrient availability, ionic composition, pH, osmolarity, oxidative stress, contact with host cells and tissues, host immune response, and intracellular life. Some of the signaling pathways and second messengers potentially involved in the response to these changes have been elucidated in recent years and will be the subject of this review.
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Affiliation(s)
- Noelia Lander
- Center for Tropical and Emerging Global Diseases, and Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Miguel A. Chiurillo
- Center for Tropical and Emerging Global Diseases, and Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Roberto Docampo
- Center for Tropical and Emerging Global Diseases, and Department of Cellular Biology, University of Georgia, Athens, GA, 30602, USA
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Abstract
AbstractDuring three decades, only about 20 new drugs have been developed for malaria, tuberculosis and all neglected tropical diseases (NTDs). This critical situation was reached because NTDs represent only 10% of health research investments; however, they comprise about 90% of the global disease burden. Computational simulations applied in virtual screening (VS) strategies are very efficient tools to identify pharmacologically active compounds or new indications for drugs already administered for other diseases. One of the advantages of this approach is the low time-consuming and low-budget first stage, which filters for testing experimentally a group of candidate compounds with high chances of binding to the target and present trypanocidal activity. In this work, we review the most common VS strategies that have been used for the identification of new drugs with special emphasis on those applied to trypanosomiasis and leishmaniasis. Computational simulations based on the selected protein targets or their ligands are explained, including the method selection criteria, examples of successful VS campaigns applied to NTDs, a list of validated molecular targets for drug development and repositioned drugs for trypanosomatid-caused diseases. Thereby, here we present the state-of-the-art of VS and drug repurposing to conclude pointing out the future perspectives in the field.
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10
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Schoijet AC, Sternlieb T, Alonso GD. Signal Transduction Pathways as Therapeutic Target for Chagas Disease. Curr Med Chem 2019; 26:6572-6589. [PMID: 31218950 DOI: 10.2174/0929867326666190620093029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 12/26/2018] [Accepted: 02/20/2019] [Indexed: 01/23/2023]
Abstract
Trypanosomatids are a group of flagellated unicellular eukaryotes, causing serious human diseases including Chagas disease (Trypanosoma cruzi), sleeping sickness (Trypanosoma brucei spp.) and Leishmaniasis (Leishmania spp.). The second messenger cAMP is involved in numerous and fundamental processes in these parasites including differentiation between stages, proliferation, osmoregulation, oxidative stress and quorum sensing. Interestingly, its signaling pathway is quite different from that of mammals, including structurally different adenylyl cyclases, the shortage of orthologous effector proteins and the absence of G-protein-coupled-receptors, among others. These characteristics make the proteins involved in these transduction pathways good candidates for therapeutic targets. However, the identification of new unknown druggable targets involves extensive research time and is economically very expensive, making difficult the transition from basic research to the clinical phase. Trypanosomatid PDEs have characteristic binding pockets that allow for a differential inhibition from their human orthologs. Modification in the approved drugs for human to convert them into trypanocidal treatments could lead to more effective therapies, shorter lab time and lower costs. In view of the fact that kinetoplastid PDEs are highly conserved with their mammalian counterparts, and since there are already numerous drugs on the market against human PDEs, the drug repositioning approach is highly promising. The development of new technologies, higher government and industrial involvement and more scientists committed to basic investigation, are the key to ultimately find an effective treatment and cure for the neglected tropical diseases.
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Affiliation(s)
- Alejandra Cecilia Schoijet
- Laboratorio de Senalizacion y Mecanismos Adaptativos en Tripanosomatidos, Instituto de Investigaciones en Ingenieria Genetica y Biologia Molecular "Dr. Hector N. Torres"; Vuelta de Obligado 2490 (C1428ADN), Buenos Aires, Argentina
| | - Tamara Sternlieb
- Laboratorio de Senalizacion y Mecanismos Adaptativos en Tripanosomatidos, Instituto de Investigaciones en Ingenieria Genetica y Biologia Molecular "Dr. Hector N. Torres"; Vuelta de Obligado 2490 (C1428ADN), Buenos Aires, Argentina
| | - Guillermo Daniel Alonso
- Laboratorio de Senalizacion y Mecanismos Adaptativos en Tripanosomatidos, Instituto de Investigaciones en Ingenieria Genetica y Biologia Molecular "Dr. Hector N. Torres"; Vuelta de Obligado 2490 (C1428ADN), Buenos Aires, Argentina.,Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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11
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Salas-Sarduy E, Niemirowicz GT, José Cazzulo J, Alvarez VE. Target-based Screening of the Chagas Box: Setting Up Enzymatic Assays to Discover Specific Inhibitors Across Bioactive Compounds. Curr Med Chem 2019; 26:6672-6686. [PMID: 31284853 DOI: 10.2174/0929867326666190705160637] [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: 06/01/2018] [Revised: 09/10/2018] [Accepted: 11/07/2018] [Indexed: 11/22/2022]
Abstract
Chagas disease is a neglected tropical illness caused by the protozoan parasite Trypanosoma cruzi. The disease is endemic in Latin America with about 6 million people infected and many more being at risk. Only two drugs are available for treatment, Nifurtimox and Benznidazole, but they have a number of side effects and are not effective in all cases. This makes urgently necessary the development of new drugs, more efficient, less toxic and affordable to the poor people, who are most of the infected population. In this review we will summarize the current strategies used for drug discovery considering drug repositioning, phenotyping screenings and target-based approaches. In addition, we will describe in detail the considerations for setting up robust enzymatic assays aimed at identifying and validating small molecule inhibitors in high throughput screenings.
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Affiliation(s)
- Emir Salas-Sarduy
- Instituto de Investigaciones Biotecnologicas Dr. Rodolfo A. Ugalde - Instituto Tecnologico de Chascomus (IIB-INTECH), Universidad Nacional de San Martin (UNSAM) - Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), Campus Miguelete, Av. 25 de Mayo y Francia, 1650 San Martin, Buenos Aires, Argentina
| | - Gabriela T Niemirowicz
- Instituto de Investigaciones Biotecnologicas Dr. Rodolfo A. Ugalde - Instituto Tecnologico de Chascomus (IIB-INTECH), Universidad Nacional de San Martin (UNSAM) - Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), Campus Miguelete, Av. 25 de Mayo y Francia, 1650 San Martin, Buenos Aires, Argentina
| | - Juan José Cazzulo
- Instituto de Investigaciones Biotecnologicas Dr. Rodolfo A. Ugalde - Instituto Tecnologico de Chascomus (IIB-INTECH), Universidad Nacional de San Martin (UNSAM) - Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), Campus Miguelete, Av. 25 de Mayo y Francia, 1650 San Martin, Buenos Aires, Argentina
| | - Vanina E Alvarez
- Instituto de Investigaciones Biotecnologicas Dr. Rodolfo A. Ugalde - Instituto Tecnologico de Chascomus (IIB-INTECH), Universidad Nacional de San Martin (UNSAM) - Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), Campus Miguelete, Av. 25 de Mayo y Francia, 1650 San Martin, Buenos Aires, Argentina
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12
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Quantitative Structure-Activity Relationships for Structurally Diverse Chemotypes Having Anti- Trypanosoma cruzi Activity. Int J Mol Sci 2019; 20:ijms20112801. [PMID: 31181717 PMCID: PMC6600563 DOI: 10.3390/ijms20112801] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 05/17/2019] [Accepted: 05/17/2019] [Indexed: 12/17/2022] Open
Abstract
Small-molecule compounds that have promising activity against macromolecular targets from Trypanosoma cruzi occasionally fail when tested in whole-cell phenotypic assays. This outcome can be attributed to many factors, including inadequate physicochemical and pharmacokinetic properties. Unsuitable physicochemical profiles usually result in molecules with a poor ability to cross cell membranes. Quantitative structure-activity relationship (QSAR) analysis is a valuable approach to the investigation of how physicochemical characteristics affect biological activity. In this study, artificial neural networks (ANNs) and kernel-based partial least squares regression (KPLS) were developed using anti-T. cruzi activity data for broadly diverse chemotypes. The models exhibited a good predictive ability for the test set compounds, yielding q2 values of 0.81 and 0.84 for the ANN and KPLS models, respectively. The results of this investigation highlighted privileged molecular scaffolds and the optimum physicochemical space associated with high anti-T. cruzi activity, which provided important guidelines for the design of novel trypanocidal agents having drug-like properties.
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13
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Silva BN, Sales Junior PA, Romanha AJ, Murta SM, Lima CH, Albuquerque MG, D'Elia E, Rodrigues JG, Ferreira VF, Silva FC, Pinto AC, Silva BV. Synthesis of New Thiosemicarbazones and Semicarbazones Containing the 1,2,3-1H-triazole-isatin Scaffold: Trypanocidal, Cytotoxicity, Electrochemical Assays, and Molecular Docking. Med Chem 2019; 15:240-256. [DOI: 10.2174/1573406414666180912120502] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 07/09/2018] [Accepted: 08/22/2018] [Indexed: 01/17/2023]
Abstract
Background:
Chagas disease, also known as American trypanosomiasis, is classified as
one of the 17 most important neglected diseases by the World Health Organization. The only drugs
with proven efficacy against Chagas disease are benznidazole and nifurtimox, however both show
adverse effects, poor clinical efficacy, and development of resistance. For these reasons, the search
for new effective chemical entities is a challenge to research groups and the pharmaceutical industry.
Objective:
Synthesis and evaluation of antitrypanosomal activities of a series of thiosemicarbazones
and semicarbazones containing 1,2,3-1H triazole isatin scaffold.
Method:
5&'-(4-alkyl/aryl)-1H-1,2,3-triazole-isatins were prepared by Huisgen 1,3-dipolar
cycloaddition and the thiosemicarbazones and semicarbazones were obtained by the 1:1 reactions
of the carbonylated derivatives with thiosemicarbazide and semicarbazide hydrochloride,
respectively, in methanol, using conventional reflux or microwave heating. The compounds were
assayed for in vitro trypanocidal activity against Trypanosoma cruzi, the aetiological agent of
Chagas disease. Beyond the thio/semicarbazone derivatives, isatin and triazole synthetic
intermediates were also evaluated for comparison.
Results:
A series of compounds were prepared in good yields. Among the 37 compounds evaluated,
18 were found to be active, in particular thiosemicarbazones containing a non-polar saturated
alkyl chain (IC50 = 24.1, 38.6, and 83.2 &µM; SI = 11.6, 11.8, and 14.0, respectively). To further
elucidate the mechanism of action of these new compounds, the redox behaviour of some active
and inactive derivatives was studied by cyclic voltammetry. Molecular docking studies were also
performed in two validated protein targets of Trypanosoma cruzi, i.e., cruzipain (CRZ) and phosphodiesterase
C (TcrPDEC).
Conclusion:
A class of thio/semicarbazones structurally simple and easily accessible was synthesized.
Compounds containing thiosemicarbazone moieties showed the best results in the series, being
more active than the corresponding semicarbazones. Our results indicated that the activity of
these compounds does not originate from an oxidation-reduction pathway but probably from the
interactions with trypanosomal enzymes.
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Affiliation(s)
- Bianca N.M. Silva
- Instituto de Quimica (IQ), Universidade Federal do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, 149, Cidade Universitaria, Ilha do Fundao, 21949-900, Rio de Janeiro, RJ, Brazil
| | - Policarpo A. Sales Junior
- Centro de Pesquisas Rene Rachou (CPqRR), Fundacao Oswaldo Cruz (FIOCRUZ), Av. Augusto de Lima, 1715, Barro Preto, 30190-002, Belo Horizonte, MG, Brazil
| | - Alvaro J. Romanha
- Centro de Pesquisas Rene Rachou (CPqRR), Fundacao Oswaldo Cruz (FIOCRUZ), Av. Augusto de Lima, 1715, Barro Preto, 30190-002, Belo Horizonte, MG, Brazil
| | - Silvane M.F. Murta
- Centro de Pesquisas Rene Rachou (CPqRR), Fundacao Oswaldo Cruz (FIOCRUZ), Av. Augusto de Lima, 1715, Barro Preto, 30190-002, Belo Horizonte, MG, Brazil
| | - Camilo H.S. Lima
- Faculdade de Farmacia (FF), Universidade Federal Fluminense (UFF), R. Mario Viana, 523, Santa Rosa, 24241- 000, Niteroi, RJ, Brazil
| | - Magaly G. Albuquerque
- Instituto de Quimica (IQ), Universidade Federal do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, 149, Cidade Universitaria, Ilha do Fundao, 21949-900, Rio de Janeiro, RJ, Brazil
| | - Eliane D'Elia
- Instituto de Quimica (IQ), Universidade Federal do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, 149, Cidade Universitaria, Ilha do Fundao, 21949-900, Rio de Janeiro, RJ, Brazil
| | - José G.A. Rodrigues
- Instituto de Quimica (IQ), Universidade Federal do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, 149, Cidade Universitaria, Ilha do Fundao, 21949-900, Rio de Janeiro, RJ, Brazil
| | - Vitor F. Ferreira
- Instituto de Quimica (IQ), Universidade Federal Fluminense (UFF), 24020-141 Niteroi, RJ, Brazil
| | - Fernando C. Silva
- Instituto de Quimica (IQ), Universidade Federal Fluminense (UFF), 24020-141 Niteroi, RJ, Brazil
| | - Angelo C. Pinto
- Instituto de Quimica (IQ), Universidade Federal do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, 149, Cidade Universitaria, Ilha do Fundao, 21949-900, Rio de Janeiro, RJ, Brazil
| | - Bárbara V. Silva
- Instituto de Quimica (IQ), Universidade Federal do Rio de Janeiro (UFRJ), Av. Athos da Silveira Ramos, 149, Cidade Universitaria, Ilha do Fundao, 21949-900, Rio de Janeiro, RJ, Brazil
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14
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Sebastián-Pérez V, Hendrickx S, Munday JC, Kalejaiye T, Martínez A, Campillo NE, de Koning H, Caljon G, Maes L, Gil C. Cyclic Nucleotide-Specific Phosphodiesterases as Potential Drug Targets for Anti-Leishmania Therapy. Antimicrob Agents Chemother 2018; 62:e00603-18. [PMID: 30104270 PMCID: PMC6153811 DOI: 10.1128/aac.00603-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 08/05/2018] [Indexed: 01/22/2023] Open
Abstract
The available treatments for leishmaniasis are less than optimal due to inadequate efficacy, toxic side effects, and the emergence of resistant strains, clearly endorsing the urgent need for discovery and development of novel drug candidates. Ideally, these should act via an alternative mechanism of action to avoid cross-resistance with the current drugs. As cyclic nucleotide-specific phosphodiesterases (PDEs) of Leishmania major have been postulated as putative drug targets, a series of potential inhibitors of Leishmania PDEs were explored. Several displayed potent and selective in vitro activity against L. infantum intracellular amastigotes. One imidazole derivative, compound 35, was shown to reduce the parasite loads in vivo and to increase the cellular cyclic AMP (cAMP) level at in a dose-dependent manner at just 2× and 5× the 50% inhibitory concentration (IC50), indicating a correlation between antileishmanial activity and increased cellular cAMP levels. Docking studies and molecular dynamics simulations pointed to imidazole 35 exerting its activity through PDE inhibition. This study establishes for the first time that inhibition of cAMP PDEs can potentially be exploited for new antileishmanial chemotherapy.
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Affiliation(s)
| | - Sarah Hendrickx
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Antwerp, Belgium
| | - Jane C Munday
- Institute of Infection, Inflammation and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Titilola Kalejaiye
- Institute of Infection, Inflammation and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Ana Martínez
- Centro de Investigaciones Biológicas (CIB, CSIC), Madrid, Spain
| | | | - Harry de Koning
- Institute of Infection, Inflammation and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Guy Caljon
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Antwerp, Belgium
| | - Louis Maes
- Laboratory for Microbiology, Parasitology and Hygiene (LMPH), University of Antwerp, Antwerp, Belgium
| | - Carmen Gil
- Centro de Investigaciones Biológicas (CIB, CSIC), Madrid, Spain
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15
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Abstract
Inorganic polyphosphate (polyP) accumulates in acidocalcisomes, acidic calcium stores that have been found from bacteria to human cells. Proton pumps, such as the vacuolar proton pyrophosphatase (V-H(+)-PPase or VP1), the vacuolar proton ATPase (V-H(+)-ATPase) or both, maintain their acidity. A vacuolar transporter chaperone (VTC) complex is involved in the synthesis and translocation of polyP to these organelles in several eukaryotes, such as yeast, trypanosomatids, Apicomplexan and algae. Studies in trypanosomatids have revealed the role of polyP and acidocalcisomes in osmoregulation and calcium signalling.
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16
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Docampo R. The origin and evolution of the acidocalcisome and its interactions with other organelles. Mol Biochem Parasitol 2015; 209:3-9. [PMID: 26523947 DOI: 10.1016/j.molbiopara.2015.10.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 10/04/2015] [Accepted: 10/19/2015] [Indexed: 01/11/2023]
Abstract
Acidocalcisomes are acidic calcium stores that have been found from bacteria to human cells. They are rich in phosphorus compounds in the form of orthophosphate (Pi), pyrophosphate (PPi), and polyphosphate (polyP) and their acidity is maintained by proton pumps such as the vacuolar proton pyrophosphatase (V-H+-PPase, or VP1), the vacuolar proton ATPase (V-H+-ATPase), or both. Recent studies in trypanosomatids and in other species have revealed their role in phosphate metabolism, and cation and water homeostasis, as suggested by the presence of novel pumps, transporters, and channels. An important role in autophagy has also been described. The study of the biogenesis of acidocalcisomes as well as of the interactions of these lysosome-related organelles with other organelles have uncovered important roles in calcium signaling and osmoregulation. Significantly, despite conservation of acidocalcisomes across all of cellular life, there is evidence for intimate integration of these organelles with eukaryotic cellular functions, and which are directly relevant to parasites.
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Affiliation(s)
- Roberto Docampo
- Center for Tropical and Global Emerging Diseases and Department of Cellular Biology, University of Georgia, Athens 30602, USA; Departamento de Patología Clínica, Universidade Estadual de Campinas, São Paulo 13083-877, Brazil.
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17
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Makin L, Gluenz E. cAMP signalling in trypanosomatids: role in pathogenesis and as a drug target. Trends Parasitol 2015; 31:373-9. [PMID: 26004537 PMCID: PMC4534343 DOI: 10.1016/j.pt.2015.04.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 04/24/2015] [Accepted: 04/24/2015] [Indexed: 12/25/2022]
Abstract
Trypanosoma brucei adenylate cyclases are implicated in modulation of host immune response and social motility. First effectors downstream of cAMP signalling were identified in Trypanosoma cruzi and T. brucei. Crystal structures reveal a unique pocket in trypanosomatid phosphodiesterases. Trypanosomatid phosphodiesterase inhibitors are promising drug candidates.
Despite recent research linking cAMP signalling to virulence in trypanosomatids and detailed studies of trypanosomatid adenylyl cyclases (ACs) and phosphodiesterases (PDEs) since their discoveries 40 years ago, downstream components of the pathway and their biological functions have remained remarkably elusive. However, in recent years, significant discoveries have been made: a role for parasite ACs has been proposed in cytokinesis, evasion of the host immune response, and social motility. cAMP phosphodiesterases PDEB1 and PDEB2 were found to be essential for survival and virulence of Trypanosoma brucei and, in Trypanosoma cruzi, PDEC2 was shown to be required for normal osmoregulation. As we discuss here, these breakthroughs have led to an ongoing surge in the development of PDE inhibitors as lead compounds for trypanocidal drugs.
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Affiliation(s)
- Laura Makin
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
| | - Eva Gluenz
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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18
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Woodring JL, Pollastri MP. Inhibitors of Protozoan Phosphodiesterases as Potential Therapeutic Approaches for Tropical Diseases. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/9783527682348.ch12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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19
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Jansen C, Wang H, Kooistra AJ, de Graaf C, Orrling KM, Tenor H, Seebeck T, Bailey D, de Esch IJP, Ke H, Leurs R. Discovery of novel Trypanosoma brucei phosphodiesterase B1 inhibitors by virtual screening against the unliganded TbrPDEB1 crystal structure. J Med Chem 2013; 56:2087-96. [PMID: 23409953 DOI: 10.1021/jm3017877] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Trypanosoma brucei cyclic nucleotide phosphodiesterase B1 (TbrPDEB1) and TbrPDEB2 have recently been validated as new therapeutic targets for human African trypanosomiasis by both genetic and pharmacological means. In this study we report the crystal structure of the catalytic domain of the unliganded TbrPDEB1 and its use for the in silico screening for new TbrPDEB1 inhibitors with novel scaffolds. The TbrPDEB1 crystal structure shows the characteristic folds of human PDE enzymes but also contains the parasite-specific P-pocket found in the structures of Leishmania major PDEB1 and Trypanosoma cruzi PDEC. The unliganded TbrPDEB1 X-ray structure was subjected to a structure-based in silico screening approach that combines molecular docking simulations with a protein-ligand interaction fingerprint (IFP) scoring method. This approach identified six novel TbrPDEB1 inhibitors with IC50 values of 10-80 μM, which may be further optimized as potential selective TbrPDEB inhibitors.
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Affiliation(s)
- Chimed Jansen
- Division of Medicinal Chemistry, Faculty of Sciences, Amsterdam Institute of Molecules, Medicines and Systems (AIMMS), VU University Amsterdam, Amsterdam, The Netherlands
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20
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New insights into roles of acidocalcisomes and contractile vacuole complex in osmoregulation in protists. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:69-113. [PMID: 23890380 DOI: 10.1016/b978-0-12-407695-2.00002-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
While free-living protists are usually subjected to hyposmotic environments, parasitic protists are also in contact with hyperosmotic habitats. Recent work in one of these parasites, Trypanosoma cruzi, has revealed that its contractile vacuole complex, which usually collects and expels excess water as a mechanism of regulatory volume decrease after hyposmotic stress, has also a role in cell shrinking when the cells are submitted to hyperosmotic stress. Trypanosomes also have an acidic calcium store rich in polyphosphate (polyP), named the acidocalcisome, which is involved in their response to osmotic stress. Here, we review newly emerging insights on the role of acidocalcisomes and the contractile vacuole complex in the cellular response to hyposmotic and hyperosmotic stresses. We also review the current state of knowledge on the composition of these organelles and their other roles in calcium homeostasis and protein trafficking.
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21
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Wang H, Kunz S, Chen G, Seebeck T, Wan Y, Robinson H, Martinelli S, Ke H. Biological and structural characterization of Trypanosoma cruzi phosphodiesterase C and Implications for design of parasite selective inhibitors. J Biol Chem 2012; 287:11788-97. [PMID: 22356915 DOI: 10.1074/jbc.m111.326777] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Trypanosoma cruzi phosphodiesterase C (TcrPDEC) is a potential new drug target for the treatment of Chagas disease but has not been well studied. This study reports the enzymatic properties of various kinetoplastid PDECs and the crystal structures of the unliganded TcrPDEC1 catalytic domain and its complex with an inhibitor. Mutations of PDEC during the course of evolution led to inactivation of PDEC in Trypanosoma brucei/Trypanosoma evansi/Trypanosoma congolense, whereas the enzyme is active in all other kinetoplastids. The TcrPDEC1 catalytic domain hydrolyzes both cAMP and cGMP with a K(m) of 23.8 μm and a k(cat) of 31 s(-1) for cAMP and a K(m) of 99.1 μm and a k(cat) of 17 s(-1) for cGMP, thus confirming its dual specificity. The crystal structures show that the N-terminal fragment wraps around the TcrPDEC catalytic domain and may thus regulate its enzymatic activity via direct interactions with the active site residues. A PDE5 selective inhibitor that has an IC(50) of 230 nm for TcrPDEC1 binds to TcrPDEC1 in an orientation opposite to that of sildenafil. This observation, together with the screen of the inhibitory potency of human PDE inhibitors against TcrPDEC, implies that the scaffold of some human PDE inhibitors might be used as the starting model for design of parasite PDE inhibitors. The structural study also identified a unique parasite pocket that neighbors the active site and may thus be valuable for the design of parasite-specific inhibitors.
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Affiliation(s)
- Huanchen Wang
- Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599-7260, USA
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22
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Abstract
Infectious diseases are an enormous burden to global health and ,since drug discovery is costly, those infectious diseases that affect the developing world are often not pursued by commercial drug-discovery efforts. Therefore, pragmatic means by which new therapeutics can be discovered are needed. One such approach is target repurposing, where pathogen targets are matched with homologous human targets that have been pursued for drug discovery for other indications. In many cases, the medicinal chemistry, structural biology and biochemistry knowledge around these human targets can be directly repurposed to launch and accelerate new drug-discovery efforts against the pathogen targets. This article describes the overarching strategy of target repurposing as a tool for initiating and prosecuting neglected disease drug-discovery programs, highlighting this approach with three case studies.
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23
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Docampo R, Jimenez V, King-Keller S, Li ZH, Moreno SNJ. The role of acidocalcisomes in the stress response of Trypanosoma cruzi. ADVANCES IN PARASITOLOGY 2011; 75:307-24. [PMID: 21820562 DOI: 10.1016/b978-0-12-385863-4.00014-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acidocalcisomes of Trypanosoma cruzi are acidic calcium-containing organelles rich in phosphorus in the form of pyrophosphate (PP(i)) and polyphosphate (poly P). Acidification of the organelles is driven by vacuolar proton pumps, one of which, the vacuolar-type proton pyrophosphatase, is absent in mammalian cells. A calcium ATPase is involved in calcium uptake, and an aquaporin is important for water transport. Enzymes involved in the synthesis and degradation of PPi and poly P are present within the organelle. Acidocalcisomes function as storage sites for cations and phosphorus, participate in PP(i) and poly P metabolism and volume regulation and are essential for virulence. A signalling pathway involving cyclic AMP generation is important for fusion of acidocalcisomes to the contractile vacuole complex, transference of aquaporin and volume regulation. This pathway is an excellent target for chemotherapy as shown by the effects of phosphodiesterase C inhibitors on parasite survival.
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Affiliation(s)
- Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, GA, USA
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24
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Seebeck T, Sterk GJ, Ke H. Phosphodiesterase inhibitors as a new generation of antiprotozoan drugs: exploiting the benefit of enzymes that are highly conserved between host and parasite. Future Med Chem 2011; 3:1289-306. [PMID: 21859303 PMCID: PMC3164761 DOI: 10.4155/fmc.11.77] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Protozoan infections remain a major unsolved medical problem in many parts of our world. A major obstacle to their treatment is the blatant lack of medication that is affordable, effective, safe and easy to administer. For some of these diseases, including human sleeping sickness, very few compounds are available, many of them old and all of them fraught with toxic side effects. We explore a new concept for developing new-generation antiprotozoan drugs that are based on phosphodiesterase (PDE) inhibitors. Such inhibitors are already used extensively in human pharmacology. Given the high degree of structural similarity between the human and the protozoan PDEs, the vast expertise available in the human field can now be applied to developing disease-specific PDE inhibitors as new antiprotozoan drugs.
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Affiliation(s)
- Thomas Seebeck
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, CH-3012 Bern, Switzerland.
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25
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Bustamante JM, Park HJ, Tarleton RL. Report of the 2nd Chagas Drug Discovery Consortium meeting, held on 3 November 2010; Atlanta GA, USA. Expert Opin Drug Discov 2011; 6:965-73. [PMID: 22646217 DOI: 10.1517/17460441.2011.602063] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Chagas disease is an infectious disease with the highest impact in Latin America and a growing worldwide problem. Chagas disease is the result of long-term, persistent infection with the protozoan parasite Trypanosoma cruzi. The current therapies for treating T. cruzi infection and thus preventing Chagas disease often have adverse effects, unpredictable efficacy and require long courses of treatment. Development of new therapies has been very limited, in part due to lack of interest but also as a result of poor support and inappropriate models for discovering and evaluating candidate drugs. The Chagas Drug Discovery Consortium (CDDC) was created with funding from the US National Institutes of Health to help address some of these issues. The goals of the CDDC are to discover and evaluate new candidate drugs and develop rigorous assays of drug efficacy. This report summarizes the second meeting of the CDDC in November 2010.
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Affiliation(s)
- Juan M Bustamante
- University of Georgia, Center for Tropical and Emerging Global Diseases , Department of Cellular Biology , Athens, 500 D.W Brooks Dr. S310 Coverdell Center, GA 30602 , USA +1 706 542 3378 ; +1 706 542 3582 ;
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26
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Abstract
Acidocalcisomes are acidic organelles containing calcium and a high concentration of phosphorus in the form of pyrophosphate (PP(i)) and polyphosphate (poly P). Organelles with these characteristics have been found from bacteria to human cells implying an early appearance and persistence over evolutionary time or their appearance by convergent evolution. Acidification of the organelles is driven by the presence of vacuolar proton pumps, one of which, the vacuolar proton pyrophosphatase, is absent in animals, where it is substituted by a vacuolar proton ATPase. A number of other pumps, antiporters, and channels have been described in acidocalcisomes of different species and are responsible for their internal content. Enzymes involved in the synthesis and degradation of PP(i) and poly P are present within the organelle. Acidocalcisomes function as storage sites for cations and phosphorus, and participate in PP(i) and poly P metabolism, calcium homeostasis, maintenance of intracellular pH, and osmoregulation. Experiments in which the acidocalcisome Ca(2+)-ATPase of different parasites were downregulated or eliminated, or acidocalcisome Ca(2+) was depleted revealed the importance of this store in Ca(2+) signaling needed for host invasion and virulence. Acidocalcisomes interact with other organelles in a number of organisms suggesting their association with the endosomal/lysosomal pathway, and are considered part of the lysosome-related group of organelles.
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27
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Abstract
Compared with the impressive progress in understanding signal transduction pathways and mechanisms in mammalian systems, advances in protozoan signalling processes, including cyclic nucleotide metabolism, have been very slow. This is in large part connected to the fact that the components of these pathways are very different in the protozoan parasites, as confirmed by the recently completed genome. For instance, kinetoplastids have no equivalents to the mammalian Class I adenylyl cyclases (ACs) in their genomes nor any of the subunits of the associated G-proteins. The cyclases in kinetoplastid parasites contain a single transmembrane domain, a conserved intracellular catalytic domain and a highly variable extracellular domain - consistent with the expression of multiple receptor-activated cyclases - but no receptor ligands, agonists or antagonists have been identified. Apicomplexan AC and guanylyl cyclase (GC) are even more unusual, potentially being bifunctional, harbouring either a putative ion channel (AC) or a P-type ATPase-like domain (GC) alongside the catalytic region. Phosphodiesterases (PDEs) and cyclic-nucleotide-activated protein kinases are essentially conserved in protozoa, although mostly insensitive to inhibitors of the mammalian proteins. Some of the PDEs have now been validated as promising drug targets. In the following manuscript, we will summarize the existing literature on cAMP and cGMP in protozoa: cyclases, PDEs and cyclic-nucleotide-dependent kinases.
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Affiliation(s)
- Matthew K Gould
- Biomedical Research Centre, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
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28
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Schoijet AC, Miranda K, Medeiros LCS, de Souza W, Flawiá MM, Torres HN, Pignataro OP, Docampo R, Alonso GD. Defining the role of a FYVE domain in the localization and activity of a cAMP phosphodiesterase implicated in osmoregulation in Trypanosoma cruzi. Mol Microbiol 2010; 79:50-62. [PMID: 21166893 DOI: 10.1111/j.1365-2958.2010.07429.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Intracellular levels of cyclic nucleotide second messengers are regulated predominantly by a large superfamily of phosphodiesterases (PDEs). Trypanosoma cruzi, the causative agent of Chagas disease, encodes four different PDE families. One of these PDEs, T. cruzi PDE C2 (TcrPDEC2) has been characterized as a FYVE domain containing protein. Here, we report a novel role for TcrPDEC2 in osmoregulation in T. cruzi and reveal the relevance of its FYVE domain. Our data show that treatment of epimastigotes with TcrPDEC2 inhibitors improves their regulatory volume decrease, whereas cells overexpressing this enzyme are unaffected by the same inhibitors. Consistent with these results, TcrPDEC2 localizes to the contractile vacuole complex, showing strong labelling in the region corresponding to the spongiome. Furthermore, transgenic parasites overexpressing a truncated version of TcrPDEC2 without the FYVE domain show a failure in its targeting to the contractile vacuole complex and a marked decrease in PDE activity, supporting the importance of this domain to the localization and activity of TcrPDEC2. Taking together, the results here presented are consistent with the importance of the cyclic AMP signalling pathway in regulatory volume decrease and implicate TcrPDEC2 as a specifically localized PDE involved in osmoregulation in T. cruzi.
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Affiliation(s)
- Alejandra C Schoijet
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Vuelta de Obligado 2490, C1428ADN Buenos Aires, Argentina
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