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Rawat RS, Gupta A, Antil N, Bhatnagar S, Singh M, Rawat A, Prasad TSK, Sharma P. Protein kinase PfPK2 mediated signalling is critical for host erythrocyte invasion by malaria parasite. PLoS Pathog 2023; 19:e1011770. [PMID: 37988347 PMCID: PMC10662742 DOI: 10.1371/journal.ppat.1011770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 10/23/2023] [Indexed: 11/23/2023] Open
Abstract
Signalling pathways in malaria parasite remain poorly defined and major reason for this is the lack of understanding of the function of majority of parasite protein kinases and phosphatases in parasite signalling and its biology. In the present study, we have elucidated the function of Protein Kinase 2 (PfPK2), which is known to be indispensable for the survival of human malaria parasite Plasmodium falciparum. We demonstrate that it is involved in the invasion of host erythrocytes, which is critical for establishing infection. In addition, PfPK2 may also be involved in the maturation of the parasite post-invasion. PfPK2 regulates the release of microneme proteins like Apical Membrane Antigen 1 (AMA1), which facilitates the formation of Tight Junction between the merozoite and host erythrocyte- a key step in the process of invasion. Comparative phosphoproteomics studies revealed that PfPK2 may be involved in regulation of several key proteins involved in invasion and signalling. Furthermore, PfPK2 regulates the generation of cGMP and the release of calcium in the parasite, which are key second messengers for the process of invasion. These and other studies have shed light on a novel signalling pathway in which PfPK2 acts as an upstream regulator of important cGMP-calcium signalling, which plays an important role in parasite invasion.
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Affiliation(s)
- Rahul Singh Rawat
- Eukaryotic Gene Expression Laboratory, National Institute of Immunology, New Delhi, India
| | - Ankit Gupta
- Eukaryotic Gene Expression Laboratory, National Institute of Immunology, New Delhi, India
| | - Neelam Antil
- Institute of Bioinformatics, International Tech Park, Bangalore, India
- Amrita School of Biotechnology, Amrita Vishwa Vidyapeetham, Kollam, India
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Sonika Bhatnagar
- Eukaryotic Gene Expression Laboratory, National Institute of Immunology, New Delhi, India
| | - Monika Singh
- Eukaryotic Gene Expression Laboratory, National Institute of Immunology, New Delhi, India
| | - Akanksha Rawat
- Eukaryotic Gene Expression Laboratory, National Institute of Immunology, New Delhi, India
| | - T. S. Keshava Prasad
- Center for Systems Biology and Molecular Medicine, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, India
| | - Pushkar Sharma
- Eukaryotic Gene Expression Laboratory, National Institute of Immunology, New Delhi, India
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2
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Kumar S, Kapkoti DS, Mina PR, Gupta M, Kumar R, Kumar P, Pathak P, Bhakuni RS, Rout P, Pal A, Darokar MP. Effect of liquiritigenin on chloroquine accumulation in digestive vacuole leading to apoptosis-like death of chloroquine-resistant P. falciparum. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 114:154738. [PMID: 36940579 DOI: 10.1016/j.phymed.2023.154738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 02/23/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Malaria remains one of the major health concerns, especially in tropical countries. Although drugs such as artemisinin-based combinations are efficient for treating Plasmodium falciparum, the growing threat from multi-drug resistance has become a major challenge. Thus, there is a constant need to identify and validate new combinations to sustain current disease control strategies to overcome the challenge of drug resistance in the malaria parasites. To meet this demand, liquiritigenin (LTG) has been found to positively interact in combination with the existing clinically used drug chloroquine (CQ), which has become unfunctional due to acquired drug resistance. PURPOSE To evaluate the best interaction between LTG and CQ against CQ- resistant strain of P. falciparum. Furthermore, the in vivo antimalarial efficacy and possible mechanism of action of the best combination was also assessed. METHODS The in vitro anti-plasmodial potential of LTG against CQ- resistant strain K1 of P. falciparum was tested using Giemsa staining method. The behaviour of the combinations was evaluated using the fix ratio method and evaluated the interaction of LTG and CQ by calculating the fractional inhibitory concentration index (FICI). Oral toxicity study was carried out in a mice model. In vivo antimalarial efficacy of LTG alone and in combination with CQ was evaluated using a four-day suppression test in a mouse model. The effect of LTG on CQ accumulation was measured using HPLC and the rate of alkalinization of the digestive vacuole. Cytosolic Ca2+ level, mitochondrial membrane potential, caspase-like activity, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, and Annexin V Apoptosis assay to assess anti-plasmodial potential. Proteomics analysis was evaluated by LC-MS/MS analysis. RESULTS LTG possesses anti-plasmodial activity on its own and it showed to be an adjuvant of CQ. In in vitro studies, LTG showed synergy with CQ only in the ratio (CQ: LTG-1:4) against CQ-resistant strain (K1) of P. falciparum. Interestingly, in vivo studies, LTG in combination with CQ showed higher chemo-suppression and enhanced mean survival time at much lower concentrations compared to individual doses of LTG and CQ against CQ- resistant strain (N67) of Plasmodium yoelli nigeriensis. LTG was found to increase the CQ accumulation into digestive vacuole, reducing the rate of alkalinization, in turn increasing cytosolic Ca2+ level, loss of mitochondrial potential, caspase-3 activity, DNA damage and externalization of phosphatidylserine of the membrane (in vitro). These observations indicate the involvement of apoptosis-like death of P. falciparum that might be due to the accumulation of CQ. CONCLUSION LTG showed synergy with CQ in the ratio LTG: CQ, 4:1) in vitro and was able to curtail the IC50 of CQ and LTG. Interestingly, in vivo in combination with CQ, LTG showed higher chemo-suppression as well as enhanced mean survival time at a much lower concentrations of both the partners as compared to an individual dose of CQ and LTG. Thus, synergistic drug combination offers the possibility to enhance CQ efficacy in chemotherapy.
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Affiliation(s)
- Saurabh Kumar
- Bioprospection and Product Development Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Deepak Singh Kapkoti
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Pooja Rani Mina
- Bioprospection and Product Development Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Madhuri Gupta
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Ravi Kumar
- Bioprospection and Product Development Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Parmanand Kumar
- Bioprospection and Product Development Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Priyanka Pathak
- Bioprospection and Product Development Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - R S Bhakuni
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Prasant Rout
- Phytochemistry Division, CSIR-Central Institute of Medicinal and Aromatic Plants, Lucknow, India
| | - Anirban Pal
- Bioprospection and Product Development Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow, India.
| | - Mahendra P Darokar
- Bioprospection and Product Development Division, CSIR- Central Institute of Medicinal and Aromatic Plants, Lucknow, India.
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Long H, Fang J, Ye L, Zhang B, Hui C, Deng X, Merchant SS, Huang K. Structural and functional regulation of Chlamydomonas lysosome-related organelles during environmental changes. PLANT PHYSIOLOGY 2023; 192:927-944. [PMID: 36946208 PMCID: PMC10231462 DOI: 10.1093/plphys/kiad189] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 02/01/2023] [Accepted: 02/16/2023] [Indexed: 06/01/2023]
Abstract
Lysosome-related organelles (LROs) are a class of heterogeneous organelles conserved in eukaryotes that primarily play a role in storage and secretion. An important function of LROs is to mediate metal homeostasis. Chlamydomonas reinhardtii is a model organism for studying metal ion metabolism; however, structural and functional analyses of LROs in C. reinhardtii are insufficient. Here, we optimized a method for purifying these organelles from 2 populations of cells: stationary phase or overloaded with iron. The morphology, elemental content, and lysosomal activities differed between the 2 preparations, even though both have phosphorus and metal ion storage functions. LROs in stationary phase cells had multiple non-membrane-bound polyphosphate granules to store phosphorus. Those in iron-overloaded cells were similar to acidocalcisomes (ACs), which have a boundary membrane and contain 1 or 2 large polyphosphate granules to store more phosphorus. We established a method for quantifying the capacity of LROs to sequester individual trace metals. Based on a comparative proteomic analysis of these 2 types of LROs, we present a comprehensive AC proteome and identified 113 putative AC proteins. The methods and protein inventories provide a framework for studying the biogenesis and modification of LROs and the mechanisms by which they participate in regulating metal ion metabolism.
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Affiliation(s)
- Huan Long
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jinhua Fang
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei Province 430072, China
| | - Lian Ye
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Baolong Zhang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China
| | - Colleen Hui
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Chemical Sciences Division, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Xuan Deng
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China
| | - Sabeeha S Merchant
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, USA
| | - Kaiyao Huang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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4
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Down the membrane hole: Ion channels in protozoan parasites. PLoS Pathog 2022; 18:e1011004. [PMID: 36580479 PMCID: PMC9799330 DOI: 10.1371/journal.ppat.1011004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Parasitic diseases caused by protozoans are highly prevalent around the world, disproportionally affecting developing countries, where coinfection with other microorganisms is common. Control and treatment of parasitic infections are constrained by the lack of specific and effective drugs, plus the rapid emergence of resistance. Ion channels are main drug targets for numerous diseases, but their potential against protozoan parasites is still untapped. Ion channels are membrane proteins expressed in all types of cells, allowing for the flow of ions between compartments, and regulating cellular functions such as membrane potential, excitability, volume, signaling, and death. Channels and transporters reside at the interface between parasites and their hosts, controlling nutrient uptake, viability, replication, and infectivity. To understand how ion channels control protozoan parasites fate and to evaluate their suitability for therapeutics, we must deepen our knowledge of their structure, function, and modulation. However, methodological approaches commonly used in mammalian cells have proven difficult to apply in protozoans. This review focuses on ion channels described in protozoan parasites of clinical relevance, mainly apicomplexans and trypanosomatids, highlighting proteins for which molecular and functional evidence has been correlated with their physiological functions.
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Alves E, Nakaya H, Guimarães E, Garcia CR. Combining IP 3 affinity chromatography and bioinformatics reveals a novel protein-IP 3 binding site on Plasmodium falciparum MDR1 transporter. CURRENT RESEARCH IN MICROBIAL SCIENCES 2022; 4:100179. [PMID: 36582189 PMCID: PMC9792294 DOI: 10.1016/j.crmicr.2022.100179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Intracellular Ca2+ mobilization induced by second messenger IP3 controls many cellular events in most of the eukaryotic groups. Despite the increasing evidence of IP3-induced Ca2+ in apicomplexan parasites like Plasmodium, responsible for malaria infection, no protein with potential function as an IP3-receptor has been identified. The use of bioinformatic analyses based on previously known sequences of IP3-receptor failed to identify potential IP3-receptor candidates in any Apicomplexa. In this work, we combine the biochemical approach of an IP3 affinity chromatography column with bioinformatic meta-analyses to identify potential vital membrane proteins that present binding with IP3 in Plasmodium falciparum. Our analyses reveal that PF3D7_0523000, a gene that codes a transport protein associated with multidrug resistance as a potential target for IP3. This work provides a new insight for probing potential candidates for IP3-receptor in Apicomplexa.
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Affiliation(s)
- Eduardo Alves
- Life Science Department, Imperial College London, London, United Kingdom
| | - Helder Nakaya
- Department of Clinical and Toxicological Analyses of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil,Computational Systems Biology Laboratory, INOVA, University of Sao Paulo, Sao Paulo, Brazil
| | - Euzébio Guimarães
- Federal University of Rio Grande do Norte, Pharmacy Department, Health Science Center, Natal, Brazil
| | - Célia R.S. Garcia
- Department of Clinical and Toxicological Analyses of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil,Corresponding author.
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Hidayati AR, Melinda, Ilmi H, Sakura T, Sakaguchi M, Ohmori J, Hartuti ED, Tumewu L, Inaoka DK, Tanjung M, Yoshida E, Tokumasu F, Kita K, Mori M, Dobashi K, Nozaki T, Syafruddin D, Hafid AF, Waluyo D, Widyawaruyanti A. Effect of geranylated dihydrochalcone from Artocarpus altilis leaves extract on Plasmodium falciparum ultrastructural changes and mitochondrial malate: Quinone oxidoreductase. Int J Parasitol Drugs Drug Resist 2022; 21:40-50. [PMID: 36565667 PMCID: PMC9798170 DOI: 10.1016/j.ijpddr.2022.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022]
Abstract
Nearly half of the world's population is at risk of being infected by Plasmodium falciparum, the pathogen of malaria. Increasing resistance to common antimalarial drugs has encouraged investigations to find compounds with different scaffolds. Extracts of Artocarpus altilis leaves have previously been reported to exhibit in vitro antimalarial activity against P. falciparum and in vivo activity against P. berghei. Despite these initial promising results, the active compound from A. altilis is yet to be identified. Here, we have identified 2-geranyl-2', 4', 3, 4-tetrahydroxy-dihydrochalcone (1) from A. altilis leaves as the active constituent of its antimalarial activity. Since natural chalcones have been reported to inhibit food vacuole and mitochondrial electron transport chain (ETC), the morphological changes in food vacuole and biochemical inhibition of ETC enzymes of (1) were investigated. In the presence of (1), intraerythrocytic asexual development was impaired, and according to the TEM analysis, this clearly affected the ultrastructure of food vacuoles. Amongst the ETC enzymes, (1) inhibited the mitochondrial malate: quinone oxidoreductase (PfMQO), and no inhibition could be observed on dihydroorotate dehydrogenase (DHODH) as well as bc1 complex activities. Our study suggests that (1) has a dual mechanism of action affecting the food vacuole and inhibition of PfMQO-related pathways in mitochondria.
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Affiliation(s)
- Agriana Rosmalina Hidayati
- Doctoral Program, Faculty of Pharmacy, Universitas Airlangga, Surabaya, Indonesia,Department of Pharmacy, Faculty of Medicine, Universitas Mataram, Mataram, Indonesia
| | - Melinda
- Research Center for Genetic Engineering, National Research and Innovation Agency (BRIN), Bogor, Indonesia
| | - Hilkatul Ilmi
- Center of Natural Product Medicine Research and Development, Institute of Tropical Disease, Universitas Airlangga, Surabaya, Indonesia
| | - Takaya Sakura
- Department of Molecular Infection Dynamics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan,School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Miako Sakaguchi
- Central Laboratory, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Junko Ohmori
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Endah Dwi Hartuti
- Research Center for Genetic Engineering, National Research and Innovation Agency (BRIN), Bogor, Indonesia,Graduate School of Biomedical Science, Nagasaki University, Nagasaki, Japan
| | - Lidya Tumewu
- Center of Natural Product Medicine Research and Development, Institute of Tropical Disease, Universitas Airlangga, Surabaya, Indonesia
| | - Daniel Ken Inaoka
- Department of Molecular Infection Dynamics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan,School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan,Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Japan
| | - Mulyadi Tanjung
- Department of Chemistry, Faculty of Science and Technology, Universitas Airlangga, Surabaya, Indonesia
| | - Eri Yoshida
- Department of Molecular Infection Dynamics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Fuyuki Tokumasu
- Department of Cellular Architecture Studies, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Kiyoshi Kita
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan,Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Japan,Department of Host-Defense Biochemistry, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Mihoko Mori
- Kitasato Institute for Life Science, Kitasato University, Tokyo, Japan
| | - Kazuyuki Dobashi
- Kitasato Institute for Life Science, Kitasato University, Tokyo, Japan
| | - Tomoyoshi Nozaki
- Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Japan
| | - Din Syafruddin
- Department of Parasitology, Faculty of Medicine, Hasanudin University, Makassar, Indonesia
| | - Achmad Fuad Hafid
- Center of Natural Product Medicine Research and Development, Institute of Tropical Disease, Universitas Airlangga, Surabaya, Indonesia,Department of Pharmaceutical Sciences, Faculty of Pharmacy, Universitas Airlangga, Surabaya, Indonesia
| | - Danang Waluyo
- Research Center for Genetic Engineering, National Research and Innovation Agency (BRIN), Bogor, Indonesia
| | - Aty Widyawaruyanti
- Center of Natural Product Medicine Research and Development, Institute of Tropical Disease, Universitas Airlangga, Surabaya, Indonesia,Department of Pharmaceutical Sciences, Faculty of Pharmacy, Universitas Airlangga, Surabaya, Indonesia,Corresponding author. Center of Natural Product Medicine Research and Development, Institute of Tropical Disease, Universitas Airlangga, Surabaya, Indonesia.
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Stasic AJ, Moreno SNJ, Carruthers VB, Dou Z. The Toxoplasma plant-like vacuolar compartment (PLVAC). J Eukaryot Microbiol 2022; 69:e12951. [PMID: 36218001 PMCID: PMC10576567 DOI: 10.1111/jeu.12951] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 10/06/2022] [Accepted: 10/07/2022] [Indexed: 11/28/2022]
Abstract
Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. T. gondii shares several characteristics with plants including a nonphotosynthetic plastid termed apicoplast and a multivesicular organelle that was named the plant-like vacuole (PLV) or vacuolar compartment (VAC). The name plant-like vacuole was selected based on its resemblance in composition and function to plant vacuoles. The name VAC represents its general vacuolar characteristics. We will refer to the organelle as PLVAC in this review. New findings in recent years have revealed that the PLVAC represents the lysosomal compartment of T. gondii which has adapted peculiarities to fulfill specific Toxoplasma needs. In this review, we discuss the composition and functions of the PLVAC highlighting its roles in ion storage and homeostasis, endocytosis, exocytosis, and autophagy.
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Affiliation(s)
- Andrew J Stasic
- Department of Microbiology, Heartland FPG, Carmel, Indiana, USA
| | - Silvia N J Moreno
- Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Georgia, Athens, USA
| | - Vern B Carruthers
- Department of Microbiology & Immunology, University of Michigan Medical School, Michigan, Ann Arbor, USA
| | - Zhicheng Dou
- Department of Biological Sciences, Clemson University, South Carolina, Clemson, USA
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8
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Edgar RCS, Counihan NA, McGowan S, de Koning-Ward TF. Methods Used to Investigate the Plasmodium falciparum Digestive Vacuole. Front Cell Infect Microbiol 2022; 11:829823. [PMID: 35096663 PMCID: PMC8794586 DOI: 10.3389/fcimb.2021.829823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 12/22/2021] [Indexed: 11/13/2022] Open
Abstract
Plasmodium falciparum malaria remains a global health problem as parasites continue to develop resistance to all antimalarials in use. Infection causes clinical symptoms during the intra-erythrocytic stage of the lifecycle where the parasite infects and replicates within red blood cells (RBC). During this stage, P. falciparum digests the main constituent of the RBC, hemoglobin, in a specialized acidic compartment termed the digestive vacuole (DV), a process essential for survival. Many therapeutics in use target one or multiple aspects of the DV, with chloroquine and its derivatives, as well as artemisinin, having mechanisms of action within this organelle. In order to better understand how current therapeutics and those under development target DV processes, techniques used to investigate the DV are paramount. This review outlines the involvement of the DV in therapeutics currently in use and focuses on the range of techniques that are currently utilized to study this organelle including microscopy, biochemical analysis, genetic approaches and metabolomic studies. Importantly, continued development and application of these techniques will aid in our understanding of the DV and in the development of new therapeutics or therapeutic partners for the future.
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Affiliation(s)
- Rebecca C. S. Edgar
- School of Medicine, Deakin University, Geelong, VIC, Australia
- The Institute for Mental and Physical Health and Clinical Translation, Deakin University, Geelong, VIC, Australia
| | - Natalie A. Counihan
- School of Medicine, Deakin University, Geelong, VIC, Australia
- The Institute for Mental and Physical Health and Clinical Translation, Deakin University, Geelong, VIC, Australia
| | - Sheena McGowan
- Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC, Australia
- Centre to Impact AMR, Monash University, Monash University, Clayton, VIC, Australia
| | - Tania F. de Koning-Ward
- School of Medicine, Deakin University, Geelong, VIC, Australia
- The Institute for Mental and Physical Health and Clinical Translation, Deakin University, Geelong, VIC, Australia
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9
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Hoff CC, Azevedo MF, Thurler AB, Maluf SEC, Melo PMS, del Rivero MA, González-Bacerio J, Carmona AK, Budu A, Gazarini ML. Overexpression of Plasmodium falciparum M1 Aminopeptidase Promotes an Increase in Intracellular Proteolysis and Modifies the Asexual Erythrocytic Cycle Development. Pathogens 2021; 10:pathogens10111452. [PMID: 34832608 PMCID: PMC8618464 DOI: 10.3390/pathogens10111452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 11/16/2022] Open
Abstract
Plasmodium falciparum, the most virulent of the human malaria parasite, is responsible for high mortality rates worldwide. We studied the M1 alanyl-aminopeptidase of this protozoan (PfA-M1), which is involved in the final stages of hemoglobin cleavage, an essential process for parasite survival. Aiming to help in the rational development of drugs against this target, we developed a new strain of P. falciparum overexpressing PfA-M1 without the signal peptide (overPfA-M1). The overPfA-M1 parasites showed a 2.5-fold increase in proteolytic activity toward the fluorogenic substrate alanyl-7-amido-4-methylcoumarin, in relation to the wild-type group. Inhibition studies showed that overPfA-M1 presented a lower sensitivity against the metalloaminopeptidase inhibitor bestatin and to other recombinant PfA-M1 inhibitors, in comparison with the wild-type strain, indicating that PfA-M1 is a target for the in vitro antimalarial activity of these compounds. Moreover, overPfA-M1 parasites present a decreased in vitro growth, showing a reduced number of merozoites per schizont, and also a decrease in the iRBC area occupied by the parasite in trophozoite and schizont forms when compared to the controls. Interestingly, the transgenic parasite displays an increase in the aminopeptidase activity toward Met-, Ala-, Leu- and Arg-7-amido-4-methylcoumarin. We also investigated the potential role of calmodulin and cysteine proteases in PfA-M1 activity. Taken together, our data show that the overexpression of PfA-M1 in the parasite cytosol can be a suitable tool for the screening of antimalarials in specific high-throughput assays and may be used for the identification of intracellular molecular partners that modulate their activity in P. falciparum.
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Affiliation(s)
- Carolina C. Hoff
- Department of Biosciences, Federal University of São Paulo, Santos 11015-020, Brazil; (C.C.H.); (M.F.A.)
| | - Mauro F. Azevedo
- Department of Biosciences, Federal University of São Paulo, Santos 11015-020, Brazil; (C.C.H.); (M.F.A.)
| | - Adriana B. Thurler
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Sarah El Chamy Maluf
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Pollyana M. S. Melo
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Maday Alonso del Rivero
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, La Habana 10400, Cuba; (M.A.d.R.); (J.G.-B.)
| | - Jorge González-Bacerio
- Center for Protein Studies, Faculty of Biology, University of Havana, Vedado, La Habana 10400, Cuba; (M.A.d.R.); (J.G.-B.)
| | - Adriana K. Carmona
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
| | - Alexandre Budu
- Department of Biophysics, Federal University of São Paulo, São Paulo 04039-032, Brazil; (A.B.T.); (S.E.C.M.); (P.M.S.M.); (A.K.C.)
- Correspondence: (A.B.); (M.L.G.)
| | - Marcos L. Gazarini
- Department of Biosciences, Federal University of São Paulo, Santos 11015-020, Brazil; (C.C.H.); (M.F.A.)
- Correspondence: (A.B.); (M.L.G.)
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Sharma M, Choudhury H, Roy R, Michaels SA, Ojo KK, Bansal A. CDPKs: The critical decoders of calcium signal at various stages of malaria parasite development. Comput Struct Biotechnol J 2021; 19:5092-5107. [PMID: 34589185 PMCID: PMC8453137 DOI: 10.1016/j.csbj.2021.08.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 08/31/2021] [Accepted: 08/31/2021] [Indexed: 12/13/2022] Open
Abstract
Calcium ions are used as important signals during various physiological processes. In malaria parasites, Plasmodium spp., calcium dependent protein kinases (CDPKs) have acquired the unique ability to sense and transduce calcium signals at various critical steps during the lifecycle, either through phosphorylation of downstream substrates or mediating formation of high molecular weight protein complexes. Calcium signaling cascades establish important crosstalk events with signaling pathways mediated by other secondary messengers such as cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). CDPKs play critical roles at various important physiological steps during parasite development in vertebrates and mosquitoes. They are also important for transmission of the parasite between the two hosts. Combined with the fact that CDPKs are not present in humans, they continue to be pursued as important targets for development of anti-malarial drugs.
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Affiliation(s)
- Manish Sharma
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Himashree Choudhury
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rajarshi Roy
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Samantha A. Michaels
- Center for Emerging and Re-emerging Infectious Diseases, Division of Allergy & Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109 USA
| | - Kayode K. Ojo
- Center for Emerging and Re-emerging Infectious Diseases, Division of Allergy & Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA 98109 USA
| | - Abhisheka Bansal
- Molecular Parasitology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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11
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de Oliveira LS, Alborghetti MR, Carneiro RG, Bastos IMD, Amino R, Grellier P, Charneau S. Calcium in the Backstage of Malaria Parasite Biology. Front Cell Infect Microbiol 2021; 11:708834. [PMID: 34395314 PMCID: PMC8355824 DOI: 10.3389/fcimb.2021.708834] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/14/2021] [Indexed: 12/26/2022] Open
Abstract
The calcium ion (Ca2+) is a ubiquitous second messenger involved in key biological processes in prokaryotes and eukaryotes. In Plasmodium species, Ca2+ signaling plays a central role in the parasite life cycle. It has been associated with parasite development, fertilization, locomotion, and host cell infection. Despite the lack of a canonical inositol-1,4,5-triphosphate receptor gene in the Plasmodium genome, pharmacological evidence indicates that inositol-1,4,5-triphosphate triggers Ca2+ mobilization from the endoplasmic reticulum. Other structures such as acidocalcisomes, food vacuole and mitochondria are proposed to act as supplementary intracellular Ca2+ reservoirs. Several Ca2+-binding proteins (CaBPs) trigger downstream signaling. Other proteins with no EF-hand motifs, but apparently involved with CaBPs, are depicted as playing an important role in the erythrocyte invasion and egress. It is also proposed that a cross-talk among kinases, which are not members of the family of Ca2+-dependent protein kinases, such as protein kinases G, A and B, play additional roles mediated indirectly by Ca2+ regulation. This statement may be extended for proteins directly related to invasion or egress, such as SUB1, ERC, IMC1I, IMC1g, GAP45 and EBA175. In this review, we update our understanding of aspects of Ca2+-mediated signaling correlated to the developmental stages of the malaria parasite life cycle.
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Affiliation(s)
- Lucas Silva de Oliveira
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
- UMR 7245 MCAM, Molécules de Communication et Adaptation des Micro-organismes, Muséum National d’Histoire Naturelle, CNRS, Équipe Parasites et Protistes Libres, Paris, France
| | - Marcos Rodrigo Alborghetti
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, Brazil
| | - Renata Garcia Carneiro
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
| | - Izabela Marques Dourado Bastos
- Laboratory of Host-Pathogen Interaction, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
| | - Rogerio Amino
- Unité Infection et Immunité Paludéennes, Institut Pasteur, Paris, France
| | - Philippe Grellier
- UMR 7245 MCAM, Molécules de Communication et Adaptation des Micro-organismes, Muséum National d’Histoire Naturelle, CNRS, Équipe Parasites et Protistes Libres, Paris, France
| | - Sébastien Charneau
- Laboratory of Biochemistry and Protein Chemistry, Department of Cell Biology, Institute of Biology, University of Brasilia, Brasilia, Brazil
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12
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Scarpelli PH, Pecenin MF, Garcia CRS. Intracellular Ca 2+ Signaling in Protozoan Parasites: An Overview with a Focus on Mitochondria. Int J Mol Sci 2021; 22:ijms22010469. [PMID: 33466510 PMCID: PMC7796463 DOI: 10.3390/ijms22010469] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/07/2020] [Accepted: 12/29/2020] [Indexed: 02/06/2023] Open
Abstract
Ca2+ signaling has been involved in controling critical cellular functions such as activation of proteases, cell death, and cell cycle control. The endoplasmatic reticulum plays a significant role in Ca2+ storage inside the cell, but mitochondria have long been recognized as a fundamental Ca2+ pool. Protozoan parasites such as Plasmodium falciparum, Toxoplasma gondii, and Trypanosoma cruzi display a Ca2+ signaling toolkit with similarities to higher eukaryotes, including the participation of mitochondria in Ca2+-dependent signaling events. This review summarizes the most recent knowledge in mitochondrial Ca2+ signaling in protozoan parasites, focusing on the mechanism involved in mitochondrial Ca2+ uptake by pathogenic protists.
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13
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Borges-Pereira L, Thomas SJ, Dos Anjos E Silva AL, Bartlett PJ, Thomas AP, Garcia CRS. The genetic Ca 2+ sensor GCaMP3 reveals multiple Ca 2+ stores differentially coupled to Ca 2+ entry in the human malaria parasite Plasmodium falciparum. J Biol Chem 2020; 295:14998-15012. [PMID: 32848018 DOI: 10.1074/jbc.ra120.014906] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/12/2020] [Indexed: 12/31/2022] Open
Abstract
Cytosolic Ca2+ regulates multiple steps in the host-cell invasion, growth, proliferation, and egress of blood-stage Plasmodium falciparum, yet our understanding of Ca2+ signaling in this endemic malaria parasite is incomplete. By using a newly generated transgenic line of P. falciparum (PfGCaMP3) that expresses constitutively the genetically encoded Ca2+ indicator GCaMP3, we have investigated the dynamics of Ca2+ release and influx elicited by inhibitors of the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase pumps, cyclopiazonic acid (CPA), and thapsigargin (Thg). Here we show that in isolated trophozoite phase parasites: (i) both CPA and Thg release Ca2+ from intracellular stores in P. falciparum parasites; (ii) Thg is able to induce Ca2+ release from an intracellular compartment insensitive to CPA; (iii) only Thg is able to activate Ca2+ influx from extracellular media, through a mechanism resembling store-operated Ca2+ entry, typical of mammalian cells; and (iv) the Thg-sensitive Ca2+ pool is unaffected by collapsing the mitochondria membrane potential with the uncoupler carbonyl cyanide m-chlorophenyl hydrazone or the release of acidic Ca2+ stores with nigericin. These data suggest the presence of two Ca2+ pools in P. falciparum with differential sensitivity to the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase pump inhibitors, and only the release of the Thg-sensitive Ca2+ store induces Ca2+ influx. Activation of the store-operated Ca2+ entry-like Ca2+ influx may be relevant for controlling processes such as parasite invasion, egress, and development mediated by kinases, phosphatases, and proteases that rely on Ca2+ levels for their activation.
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Affiliation(s)
- Lucas Borges-Pereira
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brasil; Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA
| | - Samantha J Thomas
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA
| | | | - Paula J Bartlett
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA
| | - Andrew P Thomas
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University, New Jersey Medical School, Newark, New Jersey, USA.
| | - Célia R S Garcia
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brasil.
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14
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Guerra ED, Baakdah F, Gourgas O, Tam M, Stevenson MM, Georges E, Bohle DS, Cerruti M. Inorganic ions on hemozoin surface provide a glimpse into Plasmodium biology. J Inorg Biochem 2019; 200:110808. [PMID: 31487576 DOI: 10.1016/j.jinorgbio.2019.110808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 08/23/2019] [Accepted: 08/24/2019] [Indexed: 11/30/2022]
Abstract
In malaria, Plasmodium parasites produce hemozoin (Hz) as a route to detoxify free heme released from the catabolism of hemoglobin. Hz isolated from the parasites is encapsulated in an organic layer constituted by parasite and host components. This organic coating may play a role in Hz formation and in the immunomodulatory properties attributed to Hz, and they may influence the mode of action of antimalarials that block Hz formation. In this work, we analyze the organic layer adhered to Hz, and find Na, Cl, Si, Ca and P present, in addition to organic material. Our results suggest that Na, Cl, and P adsorb during Hz release from the red blood cells, while Si and Ca derive from components present during Hz biomineralization within the digestive vacuole of the parasite. Overall, we show that inorganic elements associated with Hz surface provide insights into the biological functions of Plasmodium parasites.
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Affiliation(s)
- E Danae Guerra
- Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 2B2, Canada
| | - Fadi Baakdah
- Institute of Parasitology, McGill University, Ste Anne de Bellevue, Quebec H9X 3V9, Canada
| | - Ophélie Gourgas
- Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 2B2, Canada
| | - Mifong Tam
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Mary M Stevenson
- Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada; Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada
| | - Elias Georges
- Institute of Parasitology, McGill University, Ste Anne de Bellevue, Quebec H9X 3V9, Canada
| | - D Scott Bohle
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0C5, Canada
| | - Marta Cerruti
- Department of Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 2B2, Canada.
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15
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Evidence for Regulation of Hemoglobin Metabolism and Intracellular Ionic Flux by the Plasmodium falciparum Chloroquine Resistance Transporter. Sci Rep 2018; 8:13578. [PMID: 30206341 PMCID: PMC6134138 DOI: 10.1038/s41598-018-31715-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 08/22/2018] [Indexed: 11/30/2022] Open
Abstract
Plasmodium falciparum multidrug resistance constitutes a major obstacle to the global malaria elimination campaign. Specific mutations in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) mediate resistance to the 4-aminoquinoline drug chloroquine and impact parasite susceptibility to several partner agents used in current artemisinin-based combination therapies, including amodiaquine. By examining gene-edited parasites, we report that the ability of the wide-spread Dd2 PfCRT isoform to mediate chloroquine and amodiaquine resistance is substantially reduced by the addition of the PfCRT L272F mutation, which arose under blasticidin selection. We also provide evidence that L272F confers a significant fitness cost to asexual blood stage parasites. Studies with amino acid-restricted media identify this mutant as a methionine auxotroph. Metabolomic analysis also reveals an accumulation of short, hemoglobin-derived peptides in the Dd2 + L272F and Dd2 isoforms, compared with parasites expressing wild-type PfCRT. Physiologic studies with the ionophores monensin and nigericin support an impact of PfCRT isoforms on Ca2+ release, with substantially reduced Ca2+ levels observed in Dd2 + L272F parasites. Our data reveal a central role for PfCRT in regulating hemoglobin catabolism, amino acid availability, and ionic balance in P. falciparum, in addition to its role in determining parasite susceptibility to heme-binding 4-aminoquinoline drugs.
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16
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High-Content Screening of the Medicines for Malaria Venture Pathogen Box for Plasmodium falciparum Digestive Vacuole-Disrupting Molecules Reveals Valuable Starting Points for Drug Discovery. Antimicrob Agents Chemother 2018; 62:AAC.02031-17. [PMID: 29311064 DOI: 10.1128/aac.02031-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/20/2017] [Indexed: 02/06/2023] Open
Abstract
Plasmodium falciparum infections leading to malaria have severe clinical manifestations and high mortality rates. Chloroquine (CQ), a former mainstay of malaria chemotherapy, has been rendered ineffective due to the emergence of widespread resistance. Recent studies, however, have unveiled a novel mode of action in which low-micromolar levels of CQ permeabilized the parasite's digestive vacuole (DV) membrane, leading to calcium efflux, mitochondrial depolarization, and DNA degradation. These phenotypes implicate the DV as an alternative target of CQ and suggest that DV disruption is an attractive target for exploitation by DV-disruptive antimalarials. In the current study, high-content screening of the Medicines for Malaria Venture (MMV) Pathogen Box (2015) was performed to select compounds which disrupt the DV membrane, as measured by the leakage of intravacuolar Ca2+ using the calcium probe Fluo-4 AM. The hits were further characterized by hemozoin biocrystallization inhibition assays and dose-response half-maximal (50%) inhibitory concentration (IC50) assays across resistant and sensitive strains. Three hits, MMV676380, MMV085071, and MMV687812, were shown to demonstrate a lack of CQ cross-resistance in parasite strains and field isolates. Through systematic analyses, MMV085071 emerged as the top hit due to its rapid parasiticidal effect, low-nanomolar IC50, and good efficacy in triggering DV disruption, mitochondrial degradation, and DNA fragmentation in P. falciparum These programmed cell death (PCD)-like phenotypes following permeabilization of the DV suggests that these compounds kill the parasite by a PCD-like mechanism. From the drug development perspective, MMV085071, which was identified to be a potent DV disruptor, offers a promising starting point for subsequent hit-to-lead generation and optimization through structure-activity relationships.
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17
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Suárez-Cortés P, Gambara G, Favia A, Palombi F, Alano P, Filippini A. Ned-19 inhibition of parasite growth and multiplication suggests a role for NAADP mediated signalling in the asexual development of Plasmodium falciparum. Malar J 2017; 16:366. [PMID: 28899381 PMCID: PMC5596470 DOI: 10.1186/s12936-017-2013-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 09/04/2017] [Indexed: 11/26/2022] Open
Abstract
Background Although malaria is a preventable and curable human disease, millions of people risk to be infected by the Plasmodium parasites and to develop this illness. Therefore, there is an urgent need to identify new anti-malarial drugs. Ca2+ signalling regulates different processes in the life cycle of Plasmodium falciparum, representing a suitable target for the development of new drugs. Results This study investigated for the first time the effect of a highly specific inhibitor of nicotinic acid adenine dinucleotide phosphate (NAADP)-induced Ca2+ release (Ned-19) on P. falciparum, revealing the inhibitory effect of this compound on the blood stage development of this parasite. Ned-19 inhibits both the transition of the parasite from the early to the late trophozoite stage and the ability of the late trophozoite to develop to the multinucleated schizont stage. In addition, Ned-19 affects spontaneous intracellular Ca2+ oscillations in ring and trophozoite stage parasites, suggesting that the observed inhibitory effects may be associated to regulation of intracellular Ca2+ levels. Conclusions This study highlights the inhibitory effect of Ned-19 on progression of the asexual life cycle of P. falciparum. The observation that Ned-19 inhibits spontaneous Ca2+ oscillations suggests a potential role of NAADP in regulating Ca2+ signalling of P. falciparum. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-2013-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pablo Suárez-Cortés
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Viale Regina Elena n. 299, 00161, Rome, Italy.,Department of Vector Biology, Max-Planck Institute for Infection Biology, Charitéplatz 1, 10117, Berlin, Germany
| | - Guido Gambara
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Annarita Favia
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy.,Nucleic Acids Laboratory, Institute of Molecular Biology and Pathology, National Research Council (IBPM-CNR), Department of Biology and Biotechnologies, Sapienza University, Rome, Italy
| | - Fioretta Palombi
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Viale Regina Elena n. 299, 00161, Rome, Italy.
| | - Antonio Filippini
- Department of Anatomy, Histology, Forensic Medicine and Orthopedics, Section of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy.
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18
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Abstract
Some hours after invading the erythrocytes of its human host, the malaria parasite Plasmodium falciparum induces an increase in the permeability of the erythrocyte membrane to monovalent ions. The resulting net influx of Na(+) and net efflux of K(+), down their respective concentration gradients, converts the erythrocyte cytosol from an initially high-K(+), low-Na(+) solution to a high-Na(+), low-K(+) solution. The intraerythrocytic parasite itself exerts tight control over its internal Na(+), K(+), Cl(-), and Ca(2+) concentrations and its intracellular pH through the combined actions of a range of membrane transport proteins. The molecular mechanisms underpinning ion regulation in the parasite are receiving increasing attention, not least because PfATP4, a P-type ATPase postulated to be involved in Na(+) regulation, has emerged as a potential antimalarial drug target, susceptible to inhibition by a wide range of chemically unrelated compounds.
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Affiliation(s)
- Kiaran Kirk
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia;
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19
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Chen WJ. Honoring antiparasitics: The 2015 Nobel Prize in Physiology or Medicine. Biomed J 2016; 39:93-7. [PMID: 27372164 PMCID: PMC6139675 DOI: 10.1016/j.bj.2016.04.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 12/31/2015] [Indexed: 11/16/2022] Open
Abstract
Protozoa and helminths are the two main groups that cause parasitic diseases with a broad spectrum of clinical symptoms. Protozoa are unicellular organisms like the malaria parasite Plasmodium, which is responsible for the majority of deaths associated with parasitic infections. Helminths are alternative parasites that can produce debilitating diseases in hosts, some of which result in chronic infections. The discovery of effective therapeutic drugs is the key to improving health in regions of poverty and poor sanitation where these parasites usually occur. It is very encouraging that the 2015 Nobel Prize in Physiology or Medicine was awarded to Youyou Tu as well as William C. Campbell and Satoshi Õmura for their considerable contributions in discovering artemisinin and avermectin, respectively. Both drugs revolutionized therapies for filariasis and malaria, significantly reducing by large percentages their morbidity and mortality.
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Affiliation(s)
- Wei-June Chen
- Department of Public Health and Parasitology, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan; Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan.
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20
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Pandey K, Ferreira PE, Ishikawa T, Nagai T, Kaneko O, Yahata K. Ca(2+) monitoring in Plasmodium falciparum using the yellow cameleon-Nano biosensor. Sci Rep 2016; 6:23454. [PMID: 27006284 PMCID: PMC4804237 DOI: 10.1038/srep23454] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 03/07/2016] [Indexed: 11/09/2022] Open
Abstract
Calcium (Ca(2+))-mediated signaling is a conserved mechanism in eukaryotes, including the human malaria parasite, Plasmodium falciparum. Due to its small size (<10 μm) measurement of intracellular Ca(2+) in Plasmodium is technically challenging, and thus Ca(2+) regulation in this human pathogen is not well understood. Here we analyze Ca(2+) homeostasis via a new approach using transgenic P. falciparum expressing the Ca(2+) sensor yellow cameleon (YC)-Nano. We found that cytosolic Ca(2+) concentration is maintained at low levels only during the intraerythrocytic trophozoite stage (30 nM), and is increased in the other blood stages (>300 nM). We determined that the mammalian SERCA inhibitor thapsigargin and antimalarial dihydroartemisinin did not perturb SERCA activity. The change of the cytosolic Ca(2+) level in P. falciparum was additionally detectable by flow cytometry. Thus, we propose that the developed YC-Nano-based system is useful to study Ca(2+) signaling in P. falciparum and is applicable for drug screening.
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Affiliation(s)
- Kishor Pandey
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
- Nepal Academy of Science and Technology (NAST), GPO Box: 3323, Khumaltar, Lalitpur, Nepal
| | - Pedro E. Ferreira
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
- School of Biological Science, Nanyang Technological University, Singapore
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal
| | - Takeshi Ishikawa
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Takeharu Nagai
- The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Osamu Kaneko
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Kazuhide Yahata
- Department of Protozoology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
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21
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Ultraviolet-visible study on acid-base equilibria of aporphine alkaloids with antiplasmodial and antioxidant activities from Alseodaphne corneri and Dehaasia longipedicellata. Sci Rep 2016; 6:21517. [PMID: 26898753 PMCID: PMC4761911 DOI: 10.1038/srep21517] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 01/26/2016] [Indexed: 11/23/2022] Open
Abstract
The UV-vis spectra of isocorydine 1, norisocorydine 2 and boldine 3 were studied in 2% v/v acetonitrile, at constant ionic strength (0.1 M NaCl, 35 degree Celsius). The pKa values of isocorydine 1 and norisocorydine 2 were 11.75 and 12.07, respectively. Boldine 3 gave a pKa value of 9.16 and 10.44. All of the alkaloids 1–3 were stable at physiological pH; thereby all of them will not ionize, thus permitting the basic nitrogen to be protonated and accumulated within the acidic food vacuole of Plasmodium via pH trapping. Subsequently, acidic food vacuoles that have been neutralized by alkaloids would result in enhancement of the antiplasmodial activity. The alkaloids showed antiplasmodial activity against Plasmodium falciparum and antioxidant activities; DPPH radical scavenging, metal chelating and ferric reducing power. The antioxidant properties of the alkaloids under investigation revealed that in addition to the antiplasmodial activity, the alkaloids can also prevent oxidative damage. It can be prevented by binding free heme and neutralizing the electrons produced during the Plasmodium falciparum mediated haemoglobin destruction in the host. Slightly basic properties of the aforementioned alkaloids, along with their antioxidant activities, are advantageous in improving the suppression of malaria infection that cause less damage to the host.
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22
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Screening for Drugs Against the Plasmodium falciparum Digestive Vacuole by Imaging Flow Cytometry. Methods Mol Biol 2016; 1389:195-205. [PMID: 27460247 DOI: 10.1007/978-1-4939-3302-0_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Phenotypic assays are increasingly employed to provide clues about drug mechanisms. In antimalarial drug screening, however, the majority of assays are designed to only measure parasite-killing activity. We describe here a high-content assay to detect drug-mediated perturbation of the digestive vacuole integrity in the trophozoite stage of Plasmodium falciparum, using the ImageStream imaging flow cytometer.
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23
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Budu A, Gomes MM, Melo PM, El Chamy Maluf S, Bagnaresi P, Azevedo MF, Carmona AK, Gazarini ML. Calmidazolium evokes high calcium fluctuations in Plasmodium falciparum. Cell Signal 2015; 28:125-135. [PMID: 26689736 DOI: 10.1016/j.cellsig.2015.12.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 11/30/2015] [Accepted: 12/07/2015] [Indexed: 10/22/2022]
Abstract
Calcium and calmodulin (CaM) are important players in eukaryote cell signaling. In the present study, by using a knockin approach, we demonstrated the expression and localization of CaM in all erythrocytic stages of Plasmodium falciparum. Under extracellular Ca(2+)-free conditions, calmidazolium (CZ), a potent CaM inhibitor, promoted a transient cytosolic calcium ([Ca(2+)]cyt) increase in isolated trophozoites, indicating that CZ mobilizes intracellular sources of calcium. In the same extracellular Ca(2+)-free conditions, the [Ca(2+)]cyt rise elicited by CZ treatment was ~3.5 fold higher when the endoplasmic reticulum (ER) calcium store was previously depleted ruling out the mobilization of calcium from the ER by CZ. The effects of the Ca(2+)/H(+) ionophore ionomycin (ION) and the Na(+)/H(+) ionophore monensin (MON) suggest that the [Ca(2+)]cyt-increasing effect of CZ is driven by the removal of Ca(2+) from at least one Ca(2+)-CaM-related (CaMR) protein as well as by the mobilization of Ca(2+) from intracellular acidic calcium stores. Moreover, we showed that the mitochondrion participates in the sequestration of the cytosolic Ca(2+) elicited by CZ. Finally, the modulation of membrane Ca(2+) channels by CZ and thapsigargin (THG) was demonstrated. The opened channels were blocked by the unspecific calcium channel blocker Co(2+) but not by 2-APB (capacitative calcium entry inhibitor) or nifedipine (L-type Ca(2+) channel inhibitor). Taken together, the results suggested that one CaMR protein is an important modulator of calcium signaling and homeostasis during the Plasmodium intraerythrocytic cell cycle, working as a relevant intracellular Ca(2+) reservoir in the parasite.
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Affiliation(s)
- Alexandre Budu
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mayrim M Gomes
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil
| | - Pollyana M Melo
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Sarah El Chamy Maluf
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Piero Bagnaresi
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Mauro F Azevedo
- Instituto de Ciências Biomédicas, Universidade de São Paulo, SP, Brazil
| | - Adriana K Carmona
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
| | - Marcos L Gazarini
- Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil.
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Lourido S, Moreno SNJ. The calcium signaling toolkit of the Apicomplexan parasites Toxoplasma gondii and Plasmodium spp. Cell Calcium 2014; 57:186-93. [PMID: 25605521 DOI: 10.1016/j.ceca.2014.12.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 12/15/2014] [Indexed: 12/21/2022]
Abstract
Apicomplexan parasites have complex life cycles, frequently split between different hosts and reliant on rapid responses as the parasites react to changing environmental conditions. Calcium ion (Ca(2+)) signaling is consequently essential for the cellular and developmental changes that support Apicomplexan parasitism. Apicomplexan genomes reveal a rich repertoire of genes involved in calcium signaling, although many of the genes responsible for observed physiological changes remain unknown. There is evidence, for example, for the presence of a nifedipine-sensitive calcium entry mechanism in Toxoplasma, but the molecular components involved in Ca(2+) entry in both Toxoplasma and Plasmodium, have not been identified. The major calcium stores are the endoplasmic reticulum (ER), the acidocalcisomes, and the plant-like vacuole in Toxoplasma, or the food vacuole in Plasmodium spp. Pharmacological evidence suggests that Ca(2+) release from intracellular stores may be mediated by inositol 1,4,5-trisphosphate (IP3) or cyclic ADP ribose (cADPR) although there is no molecular evidence for the presence of receptors for these second messengers in the parasites. Several Ca(2+)-ATPases are present in Apicomplexans and a putative mitochondrial Ca(2+)/H(+) exchanger has been identified. Apicomplexan genomes contain numerous genes encoding Ca(2+)-binding proteins, with the notable expansion of calcium-dependent protein kinases (CDPKs), whose study has revealed roles in gliding motility, microneme secretion, host cell invasion and egress, and parasite differentiation. Microneme secretion has also been shown to depend on the C2 domain containing protein DOC2 in both Plasmodium spp. and Toxoplasma, providing further evidence for the complex transduction of Ca(2+) signals in these organisms. The characterization of these pathways could lead to the discovery of novel drug targets and to a better understanding of the role of Ca(2+) in these parasites.
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Affiliation(s)
- Sebastian Lourido
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases, Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA.
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Friedrich O, Reiling SJ, Wunderlich J, Rohrbach P. Assessment of Plasmodium falciparum PfMDR1 transport rates using Fluo-4. J Cell Mol Med 2014; 18:1851-62. [PMID: 24889967 PMCID: PMC4196660 DOI: 10.1111/jcmm.12313] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 03/31/2014] [Indexed: 12/18/2022] Open
Abstract
Mutations in the multidrug resistance transporter of Plasmodium falciparum PfMDR1 have been implicated to play a significant role in the emergence of worldwide drug resistance, yet the molecular and biochemical mechanisms of this transporter are not well understood. Although it is generally accepted that drug resistance in P. falciparum is partly associated with PfMDR1 transport activity situated in the membrane of the digestive vacuole, direct estimates of the pump rate of this transport process in the natural environment of the intact host–parasite system have never been analysed. The fluorochrome Fluo-4 is a well-documented surrogate substrate of PfMDR1 and has been found to accumulate by actively being transported into the digestive vacuole of several parasitic strains. In the present study, we designed an approach to use Fluo-4 fluorescence uptake as a measure of compartmental Fluo-4 concentration accumulation in the different compartments of the host–parasite system. We performed a ‘reverse Fluo-4 imaging' approach to relate fluorescence intensity to changes in dye concentration rather than Ca2+ fluctuations and were able to calculate the overall rate of transport for PfMDR1 in Dd2 parasites. With this assay, we provide a powerful method to selectively measure the effect of PfMDR1 mutations on substrate transport kinetics. This will be of high significance for future compound screening to test for new drugs in resistant P. falciparum strains.
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Affiliation(s)
- O Friedrich
- Institute of Medical Biotechnology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany; SAOT, Erlangen Graduate School of Advanced Optical Technologies, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany
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Abstract
As it grows and replicates within the erythrocytes of its host the malaria parasite takes up nutrients from the extracellular medium, exports metabolites and maintains a tight control over its internal ionic composition. These functions are achieved via membrane transport proteins, integral membrane proteins that mediate the passage of solutes across the various membranes that separate the biochemical machinery of the parasite from the extracellular environment. Proteins of this type play a key role in antimalarial drug resistance, as well as being candidate drug targets in their own right. This review provides an overview of recent work on the membrane transport biology of the malaria parasite-infected erythrocyte, encompassing both the parasite-induced changes in the membrane transport properties of the host erythrocyte and the cell physiology of the intracellular parasite itself.
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Koyama FC, Carvalho TLG, Alves E, da Silva HB, de Azevedo MF, Hemerly AS, Garcia CRS. The Structurally Related Auxin and Melatonin Tryptophan-Derivatives and their Roles in Arabidopsis thaliana
and in the Human Malaria Parasite Plasmodium falciparum. J Eukaryot Microbiol 2013; 60:646-51. [DOI: 10.1111/jeu.12080] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 07/25/2013] [Accepted: 07/25/2013] [Indexed: 11/29/2022]
Affiliation(s)
- Fernanda C. Koyama
- Departamento de Parasitologia; Instituto de Ciências Biomédicas; Universidade de São Paulo; 05508-000 São Paulo Brazil
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; 05508-090 São Paulo Brazil
| | - Thais L. G. Carvalho
- Laboratório de Biologia Molecular de Plantas; Instituto de Bioquímica Médica; Universidade Federal do Rio de Janeiro; 21941-590 Rio de Janeiro Brazil
| | - Eduardo Alves
- Departamento de Parasitologia; Instituto de Ciências Biomédicas; Universidade de São Paulo; 05508-000 São Paulo Brazil
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; 05508-090 São Paulo Brazil
| | - Henrique B. da Silva
- Departamento de Imunologia; Instituto de Ciências Biomédicas; Universidade de São Paulo; 05508-900 São Paulo Brazil
| | - Mauro F. de Azevedo
- Centre for Immunology; Macfarlane Burnet Institute of Medical Research and Public Health; Melbourne Victoria 3004 Australia
| | - Adriana S. Hemerly
- Laboratório de Biologia Molecular de Plantas; Instituto de Bioquímica Médica; Universidade Federal do Rio de Janeiro; 21941-590 Rio de Janeiro Brazil
| | - Célia R. S. Garcia
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; 05508-090 São Paulo Brazil
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Lima WR, Holder AA, Garcia CRS. Melatonin signaling and its modulation of PfNF-YB transcription factor expression in Plasmodium falciparum. Int J Mol Sci 2013; 14:13704-18. [PMID: 23839089 PMCID: PMC3742212 DOI: 10.3390/ijms140713704] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Revised: 06/23/2013] [Accepted: 06/25/2013] [Indexed: 12/15/2022] Open
Abstract
Malaria is one of the most severe tropical infectious diseases. More than 220 million people around the world have a clinical malaria infection and about one million die because of Plasmodium annually. This parasitic pathogen replicates efficiently in its human host making it difficult to eradicate. It is transmitted by mosquito vectors and so far mosquito control programs have not effectively eliminated this transmission. Because of malaria's enormous health and economic impact and the need to develop new control and eventual elimination strategies, a big research effort has been made to better understand the biology of this parasite and its interactions with its vertebrate host. Determination of the genome sequence and organization, the elucidation of the role of key proteins, and cell signaling studies have helped to develop an understanding of the molecular mechanisms that provide the parasite's versatility. The parasite can sense its environment and adapt to benefit its survival, indeed this is essential for it to complete its life cycle. For many years we have studied how the Plasmodium parasite is able to sense melatonin. In this review we discuss the melatonin signaling pathway and its role in the control of Plasmodium replication and development.
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Affiliation(s)
- Wânia Rezende Lima
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508900, Brazil; E-Mail:
| | - Anthony A. Holder
- Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK; E-Mail:
| | - Célia R. S. Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508900, Brazil; E-Mail:
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Orjih AU. Hemozoin accumulation in Garnham bodies of Plasmodium falciparum gametocytes. Parasitol Res 2012; 111:2353-9. [PMID: 22926648 DOI: 10.1007/s00436-012-3090-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 08/13/2012] [Indexed: 11/30/2022]
Abstract
Garnham bodies are curious objects exclusive in erythrocytes containing sexual forms (gametocytes) of Plasmodium falciparum. Although the name is familiar, only a few photographs of Garnham bodies (G-bodies) have been published. Considering that other objects in malaria-infected erythrocytes, such as Schuffner's dots of Plasmodium vivax and Maurer's clefts of P. falciparum, have been found to have some functions, it has become necessary to pay closer attention to G-bodies. The present study presents previously unknown features of G-bodies and suggests a protective role for them. Wild isolates of P. falciparum were encouraged to grow in vitro under conditions that promote gametocytogenesis. Thin and thick smears of the cells were stained with Giemsa stain and examined under a light microscope. Production of G-bodies was detected in two isolates both in immature and mature gametocytes. Sometimes, the objects are found both at the top and below the parasite, contrary to previous suggestion of it being only on one side. They are highly diverse in morphology, including those that are shaped like m or S. Hemozoin accumulation was detected in some of the bodies, indicating direct opening into the cystoplasm of the parasite. It is possible that hemozoin was first produced in the parasite's food vacuole before being transported to G-bodies. Alternatively, hemoglobin transport vesicles could first accumulate in G-bodies where metabolically released ferriprotoporphyrin IX (FP) could be polymerized; but this would need acidic environment comparable to that in food vacuole. Electron microscopy has revealed that G-bodies consist of membranous whorls and it has been demonstrated experimentally that both infected and uninfected membranes promote β-hematin formation. Whatever the mechanism, storing hemozoin in G-bodies outside the cytoplasm of the parasite could provide intraerythrocytic sexual forms of P. falciparum additional protection against FP toxicity.
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Affiliation(s)
- Augustine U Orjih
- Faculty of Allied Health Sciences, Department of Medical Laboratory Sciences, Kuwait University, PO Box 31740, Sulaibikhat 90805, Kuwait.
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Salcedo-Sora JE, Ward SA, Biagini GA. A yeast expression system for functional and pharmacological studies of the malaria parasite Ca²⁺/H⁺ antiporter. Malar J 2012; 11:254. [PMID: 22853777 PMCID: PMC3488005 DOI: 10.1186/1475-2875-11-254] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Accepted: 07/23/2012] [Indexed: 12/26/2022] Open
Abstract
Background Calcium (Ca2+) signalling is fundamental for host cell invasion, motility, in vivo synchronicity and sexual differentiation of the malaria parasite. Consequently, cytoplasmic free Ca2+ is tightly regulated through the co-ordinated action of primary and secondary Ca2+ transporters. Identifying selective inhibitors of Ca2+ transporters is key towards understanding their physiological role as well as having therapeutic potential, therefore screening systems to facilitate the search for potential inhibitors are a priority. Here, the methodology for the expression of a Calcium membrane transporter that can be scaled to high throughputs in yeast is presented. Methods The Plasmodium falciparum Ca2+/H+ antiporter (PfCHA) was expressed in the yeast Saccharomyces cerevisiae and its activity monitored by the bioluminescence from apoaequorin triggered by divalent cations, such as calcium, magnesium and manganese. Results Bioluminescence assays demonstrated that PfCHA effectively suppressed induced cytoplasmic peaks of Ca2+, Mg2+ and Mn2+ in yeast mutants lacking the homologue yeast antiporter Vcx1p. In the scalable format of 96-well culture plates pharmacological assays with a cation antiporter inhibitor allowed the measurement of inhibition of the Ca2+ transport activity of PfCHA conveniently translated to the familiar concept of fractional inhibitory concentrations. Furthermore, the cytolocalization of this antiporter in the yeast cells showed that whilst PfCHA seems to locate to the mitochondrion of P. falciparum, in yeast PfCHA is sorted to the vacuole. This facilitates the real-time Ca2+-loading assays for further functional and pharmacological studies. Discussion The functional expression of PfCHA in S. cerevisiae and luminescence-based detection of cytoplasmic cations as presented here offer a tractable system that facilitates functional and pharmacological studies in a high-throughput format. PfCHA is shown to behave as a divalent cation/H+ antiporter susceptible to the effects of cation/H+ inhibitors such as KB-R7943. This type of gene expression systems should advance the efforts for the screening of potential inhibitors of this type of divalent cation transporters as part of the malaria drug discovery initiatives and for functional studies in general. Conclusion The expression and activity of the PfCHA detected in yeast by a bioluminescence assay that follows the levels of cytoplasmic Ca2+ as well as Mg2+ and Mn2+ lend itself to high-throughput and quantitative settings for pharmacological screening and functional studies.
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Enomoto M, Kawazu SI, Kawai S, Furuyama W, Ikegami T, Watanabe JI, Mikoshiba K. Blockage of spontaneous Ca2+ oscillation causes cell death in intraerythrocitic Plasmodium falciparum. PLoS One 2012; 7:e39499. [PMID: 22792177 PMCID: PMC3391199 DOI: 10.1371/journal.pone.0039499] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 05/21/2012] [Indexed: 11/18/2022] Open
Abstract
Malaria remains one of the world’s most important infectious diseases and is responsible for enormous mortality and morbidity. Resistance to antimalarial drugs is a challenging problem in malaria control. Clinical malaria is associated with the proliferation and development of Plasmodium parasites in human erythrocytes. Especially, the development into the mature forms (trophozoite and schizont) of Plasmodium falciparum (P. falciparum) causes severe malaria symptoms due to a distinctive property, sequestration which is not shared by any other human malaria. Ca2+ is well known to be a highly versatile intracellular messenger that regulates many different cellular processes. Cytosolic Ca2+ increases evoked by extracellular stimuli are often observed in the form of oscillating Ca2+ spikes (Ca2+ oscillation) in eukaryotic cells. However, in lower eukaryotic and plant cells the physiological roles and the molecular mechanisms of Ca2+ oscillation are poorly understood. Here, we showed the observation of the inositol 1,4,5-trisphospate (IP3)-dependent spontaneous Ca2+ oscillation in P. falciparum without any exogenous extracellular stimulation by using live cell fluorescence Ca2+ imaging. Intraerythrocytic P. falciparum exhibited stage-specific Ca2+ oscillations in ring form and trophozoite stages which were blocked by IP3 receptor inhibitor, 2-aminoethyl diphenylborinate (2-APB). Analyses of parasitaemia and parasite size and electron micrograph of 2-APB-treated P. falciparum revealed that 2-APB severely obstructed the intraerythrocytic maturation, resulting in cell death of the parasites. Furthermore, we confirmed the similar lethal effect of 2-APB on the chloroquine-resistant strain of P. falciparum. To our best knowledge, we for the first time showed the existence of the spontaneous Ca2+ oscillation in Plasmodium species and clearly demonstrated that IP3-dependent spontaneous Ca2+ oscillation in P. falciparum is critical for the development of the blood stage of the parasites. Our results provide a novel concept that IP3/Ca2+ signaling pathway in the intraerythrocytic malaria parasites is a promising target for antimalarial drug development.
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Affiliation(s)
- Masahiro Enomoto
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako-shi, Saitama, Japan
| | - Shin-ichiro Kawazu
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Satoru Kawai
- Laboratory of Tropical Medicine and Parasitology, Dokkyo Medical University, Mibu, Tochigi, Japan
| | - Wakako Furuyama
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Tohru Ikegami
- Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Jun-ichi Watanabe
- Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako-shi, Saitama, Japan
- Japan Science and Technology Agency, International Cooperative Research Project and Solution-Oriented Research for Science and Technology, Calcium Oscillation Project, Saitama, Japan
- * E-mail:
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Generation of second messengers in Plasmodium. Microbes Infect 2012; 14:787-95. [PMID: 22584103 DOI: 10.1016/j.micinf.2012.04.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Revised: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 02/05/2023]
Abstract
Signalling in malaria parasites is a field of growing interest as its components may prove to be valuable drug targets, especially when one considers the burden of a disease that is responsible for up to 500 million infections annually. The scope of this review is to discuss external stimuli in the parasite life cycle and the upstream machinery responsible for translating them into intracellular responses, focussing particularly on the calcium signalling pathway.
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Holder AA, Mohd Ridzuan MA, Green JL. Calcium dependent protein kinase 1 and calcium fluxes in the malaria parasite. Microbes Infect 2012; 14:825-30. [PMID: 22584104 DOI: 10.1016/j.micinf.2012.04.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 04/11/2012] [Accepted: 04/11/2012] [Indexed: 01/20/2023]
Abstract
Calcium dependent protein kinases (CDPKs) are found only in plants and alveolates and are distinguished from other kinases by an activation domain that binds calcium directly. Plants contain families of these kinases and their functions are modulated by post translational modifications as well as calcium activation. Apicomplexan parasites also contain CDPK families and this review is focused on CDPK1 in Plasmodium spp. This enzyme has been implicated in parasite motility and host cell invasion and at least two substrates associated with the actomyosin motor complex have been identified. By analogy with the plant CDPKs we propose that its activity is modulated both by post translational modifications and by its subcellular location in a compartment within the parasite's pellicle, which may regulate the calcium concentration required for activation.
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Affiliation(s)
- Anthony A Holder
- Division of Parasitology, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
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Plattner H, Sehring IM, Mohamed IK, Miranda K, De Souza W, Billington R, Genazzani A, Ladenburger EM. Calcium signaling in closely related protozoan groups (Alveolata): non-parasitic ciliates (Paramecium, Tetrahymena) vs. parasitic Apicomplexa (Plasmodium, Toxoplasma). Cell Calcium 2012; 51:351-82. [PMID: 22387010 DOI: 10.1016/j.ceca.2012.01.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/10/2012] [Accepted: 01/12/2012] [Indexed: 12/20/2022]
Abstract
The importance of Ca2+-signaling for many subcellular processes is well established in higher eukaryotes, whereas information about protozoa is restricted. Recent genome analyses have stimulated such work also with Alveolates, such as ciliates (Paramecium, Tetrahymena) and their pathogenic close relatives, the Apicomplexa (Plasmodium, Toxoplasma). Here we compare Ca2+ signaling in the two closely related groups. Acidic Ca2+ stores have been characterized in detail in Apicomplexa, but hardly in ciliates. Two-pore channels engaged in Ca2+-release from acidic stores in higher eukaryotes have not been stingently characterized in either group. Both groups are endowed with plasma membrane- and endoplasmic reticulum-type Ca2+-ATPases (PMCA, SERCA), respectively. Only recently was it possible to identify in Paramecium a number of homologs of ryanodine and inositol 1,3,4-trisphosphate receptors (RyR, IP3R) and to localize them to widely different organelles participating in vesicle trafficking. For Apicomplexa, physiological experiments suggest the presence of related channels although their identity remains elusive. In Paramecium, IP3Rs are constitutively active in the contractile vacuole complex; RyR-related channels in alveolar sacs are activated during exocytosis stimulation, whereas in the parasites the homologous structure (inner membrane complex) may no longer function as a Ca2+ store. Scrutinized comparison of the two closely related protozoan phyla may stimulate further work and elucidate adaptation to parasitic life. See also "Conclusions" section.
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Affiliation(s)
- H Plattner
- Department of Biology, University of Konstanz, P.O. Box 5560, 78457 Konstanz, Germany.
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Drug-induced permeabilization of parasite's digestive vacuole is a key trigger of programmed cell death in Plasmodium falciparum. Cell Death Dis 2011; 2:e216. [PMID: 21993392 PMCID: PMC3219093 DOI: 10.1038/cddis.2011.97] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Having previously characterized chloroquine (CQ)-induced programmed cell death (PCD) hallmarks in the malaria parasite Plasmodium falciparum and delineating a pathway linking these features, the roles of non-classical mediators were investigated in this paper. It was shown that the later stages of this pathway are Ca2+-dependent and transcriptionally regulated. Moreover, it was demonstrated for the first time that micromolar concentrations of CQ partially permeabilized the parasite's digestive vacuole (DV) membrane and that this important upstream event appears to precede mitochondrial dysfunction. This permeabilization of the DV occurred without rupture of the DV membrane and was reminiscent of lysosome-mediated cell death in mammalian cells. As such micromolar concentrations of CQ are found in the patient's plasma after initial CQ loading, this alludes to a clinically relevant antimalarial mechanism of the drug which has yet to be recognized. Furthermore, other ‘non-antimalarial' lysosomotropic compounds were also shown to cause DV permeabilization, triggering PCD in both CQ-sensitive and -resistant parasites. These findings present new avenues for antimalarial developments, which induce DV destabilization to kill parasites.
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Bagnaresi P, Nakabashi M, Thomas AP, Reiter RJ, Garcia CRS. The role of melatonin in parasite biology. Mol Biochem Parasitol 2011; 181:1-6. [PMID: 21982826 DOI: 10.1016/j.molbiopara.2011.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 09/21/2011] [Accepted: 09/23/2011] [Indexed: 10/17/2022]
Abstract
Regarded as the circadian hormone in mammals, melatonin is a highly conserved molecule, present in nearly all species. In this review, we discuss the role of this indolamine and its precursors in the cell biology of parasites and the role of the molecule in the physiology of the host. In Plasmodium, melatonin can modulate intracellular concentrations of calcium and cAMP, which in turn can regulate kinase activity and cell cycle. In Trypanosoma infections, modulation of the immune system by melatonin is extremely important in controlling the parasite population. Melatonin also contributes to the inflammatory response to Toxoplasma gondii infection. Thus, there are a number of unique adaptations involving intricate connections between melatonin and the biology of the parasite-host relationship.
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Affiliation(s)
- Piero Bagnaresi
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil
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Alves E, Bartlett PJ, Garcia CRS, Thomas AP. Melatonin and IP3-induced Ca2+ release from intracellular stores in the malaria parasite Plasmodium falciparum within infected red blood cells. J Biol Chem 2010; 286:5905-12. [PMID: 21149448 DOI: 10.1074/jbc.m110.188474] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
IP(3)-dependent Ca(2+) signaling controls a myriad of cellular processes in higher eukaryotes and similar signaling pathways are evolutionarily conserved in Plasmodium, the intracellular parasite that causes malaria. We have reported that isolated, permeabilized Plasmodium chabaudi, releases Ca(2+) upon addition of exogenous IP(3). In the present study, we investigated whether the IP(3) signaling pathway operates in intact Plasmodium falciparum, the major disease-causing human malaria parasite. P. falciparum-infected red blood cells (RBCs) in the trophozoite stage were simultaneously loaded with the Ca(2+) indicator Fluo-4/AM and caged-IP(3). Photolytic release of IP(3) elicited a transient Ca(2+) increase in the cytosol of the intact parasite within the RBC. The intracellular Ca(2+) pools of the parasite were selectively discharged, using thapsigargin to deplete endoplasmic reticulum (ER) Ca(2+) and the antimalarial chloroquine to deplete Ca(2+) from acidocalcisomes. These data show that the ER is the major IP(3)-sensitive Ca(2+) store. Previous work has shown that the human host hormone melatonin regulates P. falciparum cell cycle via a Ca(2+)-dependent pathway. In the present study, we demonstrate that melatonin increases inositol-polyphosphate production in intact intraerythrocytic parasite. Moreover, the Ca(2+) responses to melatonin and uncaging of IP(3) were mutually exclusive in infected RBCs. Taken together these data provide evidence that melatonin activates PLC to generate IP(3) and open ER-localized IP(3)-sensitive Ca(2+) channels in P. falciparum. This receptor signaling pathway is likely to be involved in the regulation and synchronization of parasite cell cycle progression.
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Affiliation(s)
- Eduardo Alves
- Department of Pharmacology and Physiology, UMDNJ, New Jersey Medical School, Newark, New Jersey 07103, USA
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Krishna S, Pulcini S, Fatih F, Staines H. Artemisinins and the biological basis for the PfATP6/SERCA hypothesis. Trends Parasitol 2010; 26:517-23. [DOI: 10.1016/j.pt.2010.06.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 06/21/2010] [Accepted: 06/22/2010] [Indexed: 11/28/2022]
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Levano-Garcia J, Dluzewski AR, Markus RP, Garcia CRS. Purinergic signalling is involved in the malaria parasite Plasmodium falciparum invasion to red blood cells. Purinergic Signal 2010; 6:365-72. [PMID: 21437007 DOI: 10.1007/s11302-010-9202-y] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Accepted: 09/30/2010] [Indexed: 10/18/2022] Open
Abstract
UNLABELLED Plasmodium falciparum, the most important etiological agent of human malaria, is endowed with a highly complex cell cycle that is essential for its successful replication within the host. A number of evidence suggest that changes in parasite Ca(2+) levels occur during the intracellular cycle of the parasites and play a role in modulating its functions within the RBC. However, the molecular identification of Plasmodium receptors linked with calcium signalling and the causal relationship between Ca(2+) increases and parasite functions are still largely mysterious. We here describe that increases in P. falciparum Ca(2+) levels, induced by extracellular ATP, modulate parasite invasion. In particular, we show that addition of ATP leads to an increase of cytosolic Ca(2+) in trophozoites and segmented schizonts. Addition of the compounds KN62 and Ip5I on parasites blocked the ATP-induced rise in [Ca(2+)](c). Besides, the compounds or hydrolysis of ATP with apyrase added in culture drastically reduce RBC infection by parasites, suggesting strongly a role of extracellular ATP during RBC invasion. The use of purinoceptor antagonists Ip5I and KN62 in this study suggests the presence of putative purinoceptor in P. falciparum. In conclusion, we have demonstrated that increases in [Ca(2+)](c) in the malarial parasite P. falciparum by ATP leads to the modulation of its invasion of red blood cells. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s11302-010-9202-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Giel G van Dooren
- Plant Cell Biology Research Centre, School of Botany, The University of Melbourne, Melbourne, Vic 3010, Australia.
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Rotmann A, Sanchez C, Guiguemde A, Rohrbach P, Dave A, Bakouh N, Planelles G, Lanzer M. PfCHA is a mitochondrial divalent cation/H+ antiporter in Plasmodium falciparum. Mol Microbiol 2010; 76:1591-606. [PMID: 20487273 DOI: 10.1111/j.1365-2958.2010.07187.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human malaria parasite Plasmodium falciparum is capable of adapting to vastly different extracellular Ca(2+) environments while maintaining tight control of its intracellular Ca(2+) concentration. The mechanisms underpinning Ca(2+) homeostasis in this important pathogen are only partly understood. Here we have functionally expressed the putative Ca(2+)/H(+) antiporter PfCHA in Xenopus laevis oocytes. Our data suggest that PfCHA mediates H(+)-coupled Ca(2+) and Mn(2+) exchange. The apparent dissociation constant K(M) for Ca(2+) of 2.2 +/- 0.7 mM and the maximal velocity V(max) of 0.6 +/- 0.1 nmol per oocyte per hour are consistent with PfCHA being a low-affinity high-capacity Ca(2+) carrier. In the parasite, PfCHA was found to localize to the mitochondrion. Physiological studies conducted with live parasitized erythrocytes, and using Fluo-4 and Rhod-2 to monitor cytoplasmic and mitochondrial Ca(2+) dynamics, suggest that the mitochondrion serves as a dynamic Ca(2+) store and that PfCHA functions as a Ca(2+) efflux system expelling excess Ca(2+) from the mitochondrion. PfCHA lacks appreciable homologies to the human mitochondrial Ca(2+)/H(+) exchanger and might represent an evolutionary divergent class of mitochondrial cation antiporter, which, in turn, might provide novel opportunities for intervention.
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Affiliation(s)
- Alexander Rotmann
- Hygiene Institut, Abteilung Parasitologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
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Rohrbach P. Imaging ion flux and ion homeostasis in blood stage malaria parasites. Biotechnol J 2009; 4:812-25. [DOI: 10.1002/biot.200900084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
Apicomplexan parasites rely on calcium-mediated signaling for a variety of vital functions including protein secretion, motility, cell invasion, and differentiation. These functions are controlled by a variety of specialized systems for uptake and release of calcium, which acts as a second messenger, and on the functions of calcium-dependent proteins. Defining these systems in parasites has been complicated by their evolutionary distance from model organisms and practical concerns in working with small, and somewhat fastidious cells. Comparative genomic analyses of Toxoplasma gondii, Plasmodium spp. and Cryptosporidium spp. reveal several interesting adaptations for calcium-related processes in parasites. Apicomplexans contain several P-type Ca2+ ATPases including an ER-type reuptake mechanism (SERCA), which is the proposed target of artemisinin. All three organisms also contain several genes related to Golgi PMR-like calcium transporters, and a Ca2+/H+ exchanger, while plasma membrane-type (PMCA) Ca2+ ATPases and voltage-dependent calcium channels are exclusively found in T. gondii. Pharmacological evidence supports the presence of IP3 and ryanodine channels for calcium-mediated release. Collectively these systems regulate calcium homeostasis and release calcium to act as a signal. Downstream responses are controlled by a family of EF-hand containing calcium binding proteins including calmodulin, and an array of centrin and caltractin-like genes. Most surprising, apicomplexans contain a diversity of calcium-dependent protein kinases (CDPK), which are commonly found in plants. Toxoplasma contains more than 20 CDPK or CDPK-like proteases, while Plasmodium and Cryptosporidium have fewer than half this number. Several of these CDPKs have been shown to play vital roles in protein secretion, invasion, and differentiation, indicating that disruption of calcium-regulated pathways may provide a novel means for selective inhibition of parasites.
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Kato K, Sudo A, Kobayashi K, Tohya Y, Akashi H. Characterization of Plasmodium falciparum protein kinase 2. Mol Biochem Parasitol 2008; 162:87-95. [PMID: 18762219 DOI: 10.1016/j.molbiopara.2008.07.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2008] [Revised: 07/28/2008] [Accepted: 07/28/2008] [Indexed: 10/21/2022]
Abstract
A sustained elevation of free Ca(2+) is observed on the rupture and release of merozoites of Plasmodium falciparum from the erythrocytes. The immunoelectron micrographs demonstrate that calmodulin is localized in merozoites. To elucidate the Ca(2+) signal of P. falciparum invasion, we attempted to characterize P. falciparum protein kinase 2 (PfPK2), which is homologous to human calcium calmodulin-dependent protein kinase (CaMK). PfPK2 was purified as a fusion protein that was labeled with [gamma-(32)P]ATP; this labeling was then eliminated by phosphatase. This phosphorylation was eliminated when the putative catalytic lysine residue of PfPK2 was replaced with alanine. PfPK2 phosphorylated histone II(AS) as a representative substrate in a Ca(2+)- and calmodulin-dependent manner. Calmodulin antagonists inhibited the phosphorylation of PfPK2 in vitro and markedly decreased the parasitemia of ring forms in an invasion assay, whereas CaMKII-specific inhibitors had no effect. PfPK2 was localized in the merozoites in the culture of P. falciparum. Thus, purified PfPK2 possesses protein kinase activity in a Ca(2+)- and calmodulin-dependent manner and the catalytic lysine of this protein was determined. These data suggest that PfPK2 is the Plasmodium protein kinase expressed in the merozoites during the invasion stage.
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Affiliation(s)
- Kentaro Kato
- Department of Veterinary Microbiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
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A magneto-optic route toward the in vivo diagnosis of malaria: preliminary results and preclinical trial data. Biophys J 2008; 95:994-1000. [PMID: 18390603 DOI: 10.1529/biophysj.107.128140] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report the development of magneto-optic technology for the rapid quantitative diagnosis of malaria that may also be realizable in a noninvasive format. Hemozoin, the waste product of malarial parasitic action on hemoglobin, is produced in a form that under the action of an applied magnetic field gives rise to an induced optical dichroism characteristic of the hemozoin concentration. Here we show that precise measurement of this induced dichroism may be used to determine the level of malarial infection because this correlates, albeit in a complex manner throughout the infection cycle, with the concentration of hemozoin in the blood and tissues of infected patients. Under conservative assumptions for the production of hemozoin as a function of parasitemia, initial results indicate that the technique can match or exceed other current diagnostic techniques. The validity of the approach is confirmed by a small preliminary clinical trial on 13 patients, and measurements on live parasitized cells obtained from in vitro culture verify the possibility of producing in vivo diagnostic instrumentation.
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Garcia CRS, de Azevedo MF, Wunderlich G, Budu A, Young JA, Bannister L. Plasmodium in the postgenomic era: new insights into the molecular cell biology of malaria parasites. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 266:85-156. [PMID: 18544493 DOI: 10.1016/s1937-6448(07)66003-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this review, we bring together some of the approaches toward understanding the cellular and molecular biology of Plasmodium species and their interaction with their host red blood cells. Considerable impetus has come from the development of new methods of molecular genetics and bioinformatics, and it is important to evaluate the wealth of these novel data in the context of basic cell biology. We describe how these approaches are gaining valuable insights into the parasite-host cell interaction, including (1) the multistep process of red blood cell invasion by the merozoite; (2) the mechanisms by which the intracellular parasite feeds on the red blood cell and exports parasite proteins to modify its cytoadherent properties; (3) the modulation of the cell cycle by sensing the environmental tryptophan-related molecules; (4) the mechanism used to survive in a low Ca(2+) concentration inside red blood cells; (5) the activation of signal transduction machinery and the regulation of intracellular calcium; (6) transfection technology; and (7) transcriptional regulation and genome-wide mRNA studies in Plasmodium falciparum.
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Affiliation(s)
- Celia R S Garcia
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, CEP 05508-900, São Paulo, SP, Brazil
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Gazarini ML, Sigolo CAO, Markus RP, Thomas AP, Garcia CRS. Antimalarial drugs disrupt ion homeostasis in malarial parasites. Mem Inst Oswaldo Cruz 2007; 102:329-34. [PMID: 17568938 DOI: 10.1590/s0074-02762007000300012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Indexed: 11/21/2022] Open
Abstract
Plasmodium chabaudi malaria parasite organelles are major elements for ion homeostasis and cellular signaling and also target for antimalarial drugs. By using confocal imaging of intraerythrocytic parasites we demonstrated that the dye acridine orange (AO) is accumulated into P. chabaudi subcellular compartments. The AO could be released from the parasite organelles by collapsing the pH gradient with the K+/H+ ionophore nigericin (20 microM), or by inhibiting the H+-pump with bafilomycin (4 microM). Similarly, in isolated parasites loaded with calcium indicator Fluo 3-AM, bafilomycin caused calcium mobilization of the acidic calcium pool that could also be release with nigericin. Interestingly after complete release of the acidic compartments, addition of thapsigargin at 10 microM was still effective in releasing parasite intracellular calcium stores in parasites at trophozoite stage. The addition of antimalarial drugs chloroquine and artemisinin resulted in AO release from acidic compartments and also affected maintenance of calcium in ER store by using different drug concentrations.
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Affiliation(s)
- Marcos L Gazarini
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Súo Paulo, Brasil.
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Oliveras-Vergés A, Espel-Masferrer E. Elevated basal hepcidin levels in the liver may inhibit the development of malaria infection: another piece towards solving the malaria puzzle? Med Hypotheses 2007; 70:630-4. [PMID: 17766053 DOI: 10.1016/j.mehy.2007.07.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Accepted: 07/05/2007] [Indexed: 10/22/2022]
Abstract
BACKGROUND Inflammatory cytokines play a crucial role in the human immune response to infection by malaria. During the initial sporozoite infection of the liver the presence of Interleukin-6 (IL-6) can be determinant. IL-6 controls systemic iron homeostasis through hepcidin, which is produced mainly by hepatocytes. An elevated basal hepcidin level in the liver can be induced by chronic inflammatory disease. Hepcidin is also a peptide with antimicrobial properties. PRESENTATION OF THE HYPOTHESIS We hypothesize that elevated basal hepcidin levels in the liver inhibit the development of malaria infection. When hepcidin is abundant, hepatocytes sequester iron, and this inhibits sporozoite development in liver-stage malaria infection. TESTING THE HYPOTHESIS The validity of our hypothesis can be proven by observing sporozoite growth in hepcidin-treated hepatocytes, or in hepatocytes, stimulated with IL-6 to increase hepcidin levels before incubation with malaria sporozoites and observing the effect the hepcidin knockout function has on the infection. IMPLICATIONS OF THE HYPOTHESIS Confirmation of our hypothesis could help to understand the complexity of the malaria infection.
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Affiliation(s)
- Albert Oliveras-Vergés
- Department of Signal Theory and Communications, Technical University of Catalonia-UPC, Jordi Girona 1-3, 08034 Barcelona, Spain.
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Reeves DC, Liebelt DA, Lakshmanan V, Roepe PD, Fidock DA, Akabas MH. Chloroquine-resistant isoforms of the Plasmodium falciparum chloroquine resistance transporter acidify lysosomal pH in HEK293 cells more than chloroquine-sensitive isoforms. Mol Biochem Parasitol 2006; 150:288-99. [PMID: 17014918 PMCID: PMC1687154 DOI: 10.1016/j.molbiopara.2006.09.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 08/31/2006] [Accepted: 09/03/2006] [Indexed: 01/04/2023]
Abstract
The emergence of chloroquine-resistant Plasmodium falciparum malaria imperils the lives of millions of people in Africa, Southeast Asia and South America. Chloroquine resistance is associated with mutations in the P. falciparum chloroquine resistance transporter (PfCRT). We expressed chloroquine-sensitive (HB3) and resistant (Dd2) pfcrt alleles in HEK293 human embryonic kidney cells. PfCRT localized to the lysosomal limiting membrane and was not detected in the plasma membrane. We observed significant acidification of lysosomes containing PfCRT HB3 and Dd2, with Dd2 acidifying significantly more than HB3. A mutant HB3 allele expressing the K76T mutation (earlier found to be key for chloroquine resistance) acidified to the same extent as Dd2, whereas the acidification by a Dd2 allele expressing the T76K "back mutation" was significantly less than Dd2. Thus, the amino acid at position 76 is both an important determinant of chloroquine resistance in parasites and of lysosomal acidification following heterologous expression. PfCRT may be capable of modulating the pH of the parasite digestive vacuole, and thus chloroquine availability. Chloroquine accumulation and glycyl-phenylalanine-2-naphthylamide-induced release of lysosomal Ca(2+) stores were unaffected by PfCRT expression. Cytoplasmic domain mutations did not alter PfCRT sorting to the lysosomal membrane. This heterologous expression system will be useful to characterize PfCRT protein structure and function, and elucidate its molecular role in chloroquine resistance.
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Affiliation(s)
- David C Reeves
- Department of Physiology and Biophysics, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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Sturm A, Amino R, van de Sand C, Regen T, Retzlaff S, Rennenberg A, Krueger A, Pollok JM, Menard R, Heussler VT. Manipulation of host hepatocytes by the malaria parasite for delivery into liver sinusoids. Science 2006; 313:1287-90. [PMID: 16888102 DOI: 10.1126/science.1129720] [Citation(s) in RCA: 347] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The merozoite stage of the malaria parasite that infects erythrocytes and causes the symptoms of the disease is initially formed inside host hepatocytes. However, the mechanism by which hepatic merozoites reach blood vessels (sinusoids) in the liver and escape the host immune system before invading erythrocytes remains unknown. Here, we show that parasites induce the death and the detachment of their host hepatocytes, followed by the budding of parasite-filled vesicles (merosomes) into the sinusoid lumen. Parasites simultaneously inhibit the exposure of phosphatidylserine on the outer leaflet of host plasma membranes, which act as "eat me" signals to phagocytes. Thus, the hepatocyte-derived merosomes appear to ensure both the migration of parasites into the bloodstream and their protection from host immunity.
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Affiliation(s)
- Angelika Sturm
- Bernhard Nocht Institute for Tropical Medicine, Bernhard-Nocht-Strasse 74, 20359 Hamburg, Germany
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