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Fischer Weinberger R, Bachmaier S, Ober V, Githure GB, Dandugudumula R, Phan IQ, Almoznino M, Polatoglou E, Tsigankov P, Nitzan Koren R, Myler PJ, Boshart M, Zilberstein D. A divergent protein kinase A regulatory subunit essential for morphogenesis of the human pathogen Leishmania. PLoS Pathog 2024; 20:e1012073. [PMID: 38551993 PMCID: PMC11006142 DOI: 10.1371/journal.ppat.1012073] [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: 08/25/2023] [Revised: 04/10/2024] [Accepted: 02/26/2024] [Indexed: 04/11/2024] Open
Abstract
Parasitic protozoa of the genus Leishmania cycle between the phagolysosome of mammalian macrophages, where they reside as rounded intracellular amastigotes, and the midgut of female sand flies, which they colonize as elongated extracellular promastigotes. Previous studies indicated that protein kinase A (PKA) plays an important role in the initial steps of promastigote differentiation into amastigotes. Here, we describe a novel regulatory subunit of PKA (which we have named PKAR3) that is unique to Leishmania and most (but not all) other Kinetoplastidae. PKAR3 is localized to subpellicular microtubules (SPMT) in the cell cortex, where it recruits a specific catalytic subunit (PKAC3). Promastigotes of pkar3 or pkac3 null mutants lose their elongated shape and become rounded but remain flagellated. Truncation of an N-terminal formin homology (FH)-like domain of PKAR3 results in its detachment from the SPMT, also leading to rounded promastigotes. Thus, the tethering of PKAC3 via PKAR3 at the cell cortex is essential for maintenance of the elongated shape of promastigotes. This role of PKAR3 is reminiscent of PKARIβ and PKARIIβ binding to microtubules of mammalian neurons, which is essential for the elongation of dendrites and axons, respectively. Interestingly, PKAR3 binds nucleoside analogs, but not cAMP, with a high affinity similar to the PKAR1 isoform of Trypanosoma. We propose that these early-diverged protists have re-purposed PKA for a novel signaling pathway that spatiotemporally controls microtubule remodeling and cell shape.
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Affiliation(s)
| | - Sabine Bachmaier
- Faculty of Biology, Genetics, Ludwig-Maximilians Universität München, Martinsried, Germany
| | - Veronica Ober
- Faculty of Biology, Genetics, Ludwig-Maximilians Universität München, Martinsried, Germany
| | - George B. Githure
- Faculty of Biology, Genetics, Ludwig-Maximilians Universität München, Martinsried, Germany
| | - Ramu Dandugudumula
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Isabelle Q. Phan
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
| | - Michal Almoznino
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Eleni Polatoglou
- Faculty of Biology, Genetics, Ludwig-Maximilians Universität München, Martinsried, Germany
| | - Polina Tsigankov
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Roni Nitzan Koren
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Peter J. Myler
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington, United States of America
- Center for Global Infectious Disease Research, Seattle Children’s Research Institute, Seattle, Washington, United States of America
- Department of Pediatrics, Department of Biomedical Informatics & Medical Education, and Department of Global Health, University of Washington, Seattle, Washington, United States of America
| | - Michael Boshart
- Faculty of Biology, Genetics, Ludwig-Maximilians Universität München, Martinsried, Germany
| | - Dan Zilberstein
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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Schoijet AC, Sternlieb T, Alonso GD. Signal Transduction Pathways as Therapeutic Target for Chagas Disease. Curr Med Chem 2019; 26:6572-6589. [PMID: 31218950 DOI: 10.2174/0929867326666190620093029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 12/26/2018] [Accepted: 02/20/2019] [Indexed: 01/23/2023]
Abstract
Trypanosomatids are a group of flagellated unicellular eukaryotes, causing serious human diseases including Chagas disease (Trypanosoma cruzi), sleeping sickness (Trypanosoma brucei spp.) and Leishmaniasis (Leishmania spp.). The second messenger cAMP is involved in numerous and fundamental processes in these parasites including differentiation between stages, proliferation, osmoregulation, oxidative stress and quorum sensing. Interestingly, its signaling pathway is quite different from that of mammals, including structurally different adenylyl cyclases, the shortage of orthologous effector proteins and the absence of G-protein-coupled-receptors, among others. These characteristics make the proteins involved in these transduction pathways good candidates for therapeutic targets. However, the identification of new unknown druggable targets involves extensive research time and is economically very expensive, making difficult the transition from basic research to the clinical phase. Trypanosomatid PDEs have characteristic binding pockets that allow for a differential inhibition from their human orthologs. Modification in the approved drugs for human to convert them into trypanocidal treatments could lead to more effective therapies, shorter lab time and lower costs. In view of the fact that kinetoplastid PDEs are highly conserved with their mammalian counterparts, and since there are already numerous drugs on the market against human PDEs, the drug repositioning approach is highly promising. The development of new technologies, higher government and industrial involvement and more scientists committed to basic investigation, are the key to ultimately find an effective treatment and cure for the neglected tropical diseases.
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Affiliation(s)
- Alejandra Cecilia Schoijet
- Laboratorio de Senalizacion y Mecanismos Adaptativos en Tripanosomatidos, Instituto de Investigaciones en Ingenieria Genetica y Biologia Molecular "Dr. Hector N. Torres"; Vuelta de Obligado 2490 (C1428ADN), Buenos Aires, Argentina
| | - Tamara Sternlieb
- Laboratorio de Senalizacion y Mecanismos Adaptativos en Tripanosomatidos, Instituto de Investigaciones en Ingenieria Genetica y Biologia Molecular "Dr. Hector N. Torres"; Vuelta de Obligado 2490 (C1428ADN), Buenos Aires, Argentina
| | - Guillermo Daniel Alonso
- Laboratorio de Senalizacion y Mecanismos Adaptativos en Tripanosomatidos, Instituto de Investigaciones en Ingenieria Genetica y Biologia Molecular "Dr. Hector N. Torres"; Vuelta de Obligado 2490 (C1428ADN), Buenos Aires, Argentina.,Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina
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Druggable Targets in Cyclic Nucleotide Signaling Pathways in Apicomplexan Parasites and Kinetoplastids against Disabling Protozoan Diseases in Humans. Int J Mol Sci 2019; 20:ijms20010138. [PMID: 30609697 PMCID: PMC6337498 DOI: 10.3390/ijms20010138] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 12/19/2018] [Accepted: 12/24/2018] [Indexed: 12/20/2022] Open
Abstract
Cell signaling in eukaryotes is an evolutionarily conserved mechanism to respond and adapt to various environmental changes. In general, signal sensation is mediated by a receptor which transfers the signal to a cascade of effector proteins. The cyclic nucleotides 3′,5′-cyclic adenosine monophosphate (cAMP) and 3′,5′-cyclic guanosine monophosphate (cGMP) are intracellular messengers mediating an extracellular stimulus to cyclic nucleotide-dependent kinases driving a change in cell function. In apicomplexan parasites and kinetoplastids, which are responsible for a variety of neglected, tropical diseases, unique mechanisms of cyclic nucleotide signaling are currently identified. Collectively, cyclic nucleotides seem to be essential for parasitic proliferation and differentiation. However, there is no a genomic evidence for canonical G-proteins in these parasites while small GTPases and secondary effector proteins with structural differences to host orthologues occur. Database entries encoding G-protein-coupled receptors (GPCRs) are still without functional proof. Instead, signals from the parasite trigger GPCR-mediated signaling in the host during parasite invasion and egress. The role of cyclic nucleotide signaling in the absence of G-proteins and GPCRs, with a particular focus on small GTPases in pathogenesis, is reviewed here. Due to the absence of G-proteins, apicomplexan parasites and kinetoplastids may use small GTPases or their secondary effector proteins and host canonical G-proteins during infection. Thus, the feasibility of targeting cyclic nucleotide signaling pathways in these parasites, will be an enormous challenge for the identification of selective, pharmacological inhibitors since canonical host proteins also contribute to pathogenesis.
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Sun H, Wang S, Zhao X, Yao C, Zhuang H, Huang Y, Chen X, Yang Y, Du A. Targeted overexpression of cyclic AMP-dependent protein kinase subunit in Toxoplasma gondii promotes replication and virulence in host cells. Vet Parasitol 2017; 243:248-255. [PMID: 28807302 DOI: 10.1016/j.vetpar.2017.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 05/20/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022]
Abstract
Toxoplasma gondii (T. gondii) is one of the most common parasite that can infect almost any warm-blooded animals including humans. The cyclic nucleotide-dependent protein kinase (PKA) regulates a spectrum of intracellular signal pathways in many organisms. Protein kinase catalytic subunit (PKAC) is the core of the whole protein, and plays an important role in the life cycle of T.gondii. Here, T.gondii PKAC (TgPKAC) overexpression strain (TgPKAC-OE) was constructed. The growth of the TgPKAC-OE, RH△Ku80, and TgPKAC inhibition strains (TgPKAC-H89) were analysed by SYBR-green real-time PCR, and the ultrastructure was observed by transmission electron microscopy. The survival rate in mice was also recorded to analyse the virulence of the parasites. We also investigated the subcellular localization of TgPKAC in Vero cells by laser scanning microscope. We found that TgPKAC-OE strain exhibited obviously increased growth rate in Vero cells in vitro, and infected mice survived for a shorter time compared to wild type strain. Ultrastructural analysis found more autophagosomes-like structures in TgPKAC-H89 parasite compared to RH△Ku80 strain, and the relative expression level of Toxoplasma gondii autophagy-related protein (ATG8) in TgPKAC-H89 parasite was higher than wild type parasite. Laser confocal results showed that TgPKAC was mainly expressed in the cytoplasm of Vero cells. In conclusion, we hypothesized that inhibition of TgPKAC could cause autophagy of Toxoplasma gondii and then influence the replication of the parasite. TgPKAC plays an important role in parasite virulence in vivo, and the subcellular localization was successfully detected in Vero cells. Our data will provide a basis for further study of TgPKAC function and help screen drug targets of T. gondii.
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Affiliation(s)
- Hongchao Sun
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Suhua Wang
- Wenzhou Entry-exit Inspection and Quarantine Bureau, Wenzhou, Zhejiang 325027, China
| | - Xianfeng Zhao
- Shenzhen Entry-exit Inspection and Quarantine Bureau, Shenzhen, Guangdong 518045, China
| | - Chaoqun Yao
- Department of Biomedical Sciences and One Health Center for Zoonoses and Tropical Veterinary Medicine, Ross University School of Veterinary Medicine, P.O. Box 334, Basseterre, St. Kitts, West Indies
| | - Haohan Zhuang
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yechuan Huang
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Xueqiu Chen
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Yi Yang
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China
| | - Aifang Du
- College of Animal Sciences, Zhejiang Provincial Key Laboratory of Preventive Veterinary Medicine, Zhejiang University, Hangzhou 310058, China.
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Tagoe DNA, Kalejaiye TD, de Koning HP. The ever unfolding story of cAMP signaling in trypanosomatids: vive la difference! Front Pharmacol 2015; 6:185. [PMID: 26441645 PMCID: PMC4561360 DOI: 10.3389/fphar.2015.00185] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/17/2015] [Indexed: 12/25/2022] Open
Abstract
Kinetoplastids are unicellular, eukaryotic, flagellated protozoans containing the eponymous kinetoplast. Within this order, the family of trypanosomatids are responsible for some of the most serious human diseases, including Chagas disease (Trypanosoma cruzi), sleeping sickness (Trypanosoma brucei spp.), and leishmaniasis (Leishmania spp). Although cAMP is produced during the life cycle stages of these parasites, its signaling pathways are very different from those of mammals. The absence of G-protein-coupled receptors, the presence of structurally different adenylyl cyclases, the paucity of known cAMP effector proteins and the stringent need for regulation of cAMP in the small kinetoplastid cells all suggest a significantly different biochemical pathway and likely cell biology. However, each of the main kinetoplastid parasites express four class 1-type cyclic nucleotide-specific phosphodiesterases (PDEA-D), which have highly similar catalytic domains to that of human PDEs. To date, only TbrPDEB, expressed as two slightly different isoforms TbrPDEB1 and B2, has been found to be essential when ablated. Although the genomes contain reasonably well conserved genes for catalytic and regulatory domains of protein kinase A, these have been shown to have varied structural and functional roles in the different species. Recent discovery of a role of cAMP/AMP metabolism in a quorum-sensing signaling pathway in T. brucei, and the identification of downstream cAMP Response Proteins (CARPs) whose expression levels correlate with sensitivity to PDE inhibitors, suggests a complex signaling cascade. The interplay between the roles of these novel CARPs and the quorum-sensing signaling pathway on cell division and differentiation makes for intriguing cell biology and a new paradigm in cAMP signal transduction, as well as potential targets for trypanosomatid-specific cAMP pathway-based therapeutics.
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Affiliation(s)
- Daniel N A Tagoe
- Wellcome Trust Centre for Molecular Parasitology, University of Glasgow , Glasgow, UK ; Institute of Infection, Inflammation and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK ; Department of Laboratory Technology, Division of Medical Laboratory Technology, University of Cape Coast , Cape Coast, Ghana
| | - Titilola D Kalejaiye
- Institute of Infection, Inflammation and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK
| | - Harry P de Koning
- Institute of Infection, Inflammation and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow , Glasgow, UK
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Bhattacharya A, Biswas A, Das PK. Identification of a protein kinase A regulatory subunit from Leishmania having importance in metacyclogenesis through induction of autophagy. Mol Microbiol 2012; 83:548-64. [PMID: 22168343 DOI: 10.1111/j.1365-2958.2011.07950.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
cAMP-mediated responses act as modulators of environmental sensing and cellular differentiation of many kinetoplastidae parasites including Leishmania. Although cAMP synthesizing (adenylate cyclase) and degrading (phosphodiesterase) enzymes have been cloned and characterized from Leishmania, no cAMP-binding effector molecule has yet been identified from this parasite. In this study, a regulatory subunit of cAMP-dependent protein kinase (Ldpkar1), homologous to mammalian class I cAMP-dependent protein kinase regulatory subunit, has been identified from L. donovani. Further characterization suggested possible interaction of LdPKAR1 with PKA catalytic subunits and inhibition of PKA activity. This PKA regulatory subunit is expressed in all life cycle stages and its expression attained maximum level in stationary phase promastigotes, which are biochemically similar to the infective metacyclic promastigotes. Starvation condition, the trigger for metacyclogenesis in the parasite, elevates LdPKAR1 expression and under starvation condition promastigotes overexpressing Ldpkar1 attained metacyclic features earlier than normal cells. Furthermore, Ldpkar1 overexpression accelerates autophagy, a starvation-induced cytological event necessary for metacyclogenesis and amastigote formation. Conditional silencing of Ldpkar1 delays the induction of autophagy in the parasite. The study, for the first time, reports the identification of a functional cAMP-binding effector molecule from Leishmania that may modulate important cytological events affecting metacyclogenesis.
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Biswas A, Bhattacharya A, Das PK. Role of cAMP Signaling in the Survival and Infectivity of the Protozoan Parasite, Leishmania donovani. Mol Biol Int 2011; 2011:782971. [PMID: 22091412 PMCID: PMC3200087 DOI: 10.4061/2011/782971] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 04/01/2011] [Indexed: 11/21/2022] Open
Abstract
Leishmania donovani, while invading macrophages, encounters striking shift in temperature and pH (from 22°C and pH 7.2 to 37°C and pH 5.5), which act as the key environmental trigger for differentiation, and increases cAMP level and cAMP-mediated responses. For comprehensive understanding of cAMP signaling, we studied the enzymes related to cAMP metabolism. A stage-specific and developmentally regulated isoform of receptor adenylate cyclase (LdRACA) showed to regulate differentiation-coupled induction of cAMP. The soluble acidocalcisomal pyrophosphatase, Ldvsp1, was the major isoform regulating cAMP level in association with LdRACA. A differentially expressed soluble cytosolic cAMP phosphodiesterase (LdPDEA) might be related to infection establishment by shifting trypanothione pool utilization bias toward antioxidant defense. We identified and cloned a functional cAMP-binding effector molecule from L. donovani (a regulatory subunit of cAMP-dependent protein kinase, LdPKAR) that may modulate metacyclogenesis through induction of autophagy. This study reveals the significance of cAMP signaling in parasite survival and infectivity.
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Affiliation(s)
- Arunima Biswas
- Molecular Cell Biology Laboratory, Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata 700032, India
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Abstract
Compared with the impressive progress in understanding signal transduction pathways and mechanisms in mammalian systems, advances in protozoan signalling processes, including cyclic nucleotide metabolism, have been very slow. This is in large part connected to the fact that the components of these pathways are very different in the protozoan parasites, as confirmed by the recently completed genome. For instance, kinetoplastids have no equivalents to the mammalian Class I adenylyl cyclases (ACs) in their genomes nor any of the subunits of the associated G-proteins. The cyclases in kinetoplastid parasites contain a single transmembrane domain, a conserved intracellular catalytic domain and a highly variable extracellular domain - consistent with the expression of multiple receptor-activated cyclases - but no receptor ligands, agonists or antagonists have been identified. Apicomplexan AC and guanylyl cyclase (GC) are even more unusual, potentially being bifunctional, harbouring either a putative ion channel (AC) or a P-type ATPase-like domain (GC) alongside the catalytic region. Phosphodiesterases (PDEs) and cyclic-nucleotide-activated protein kinases are essentially conserved in protozoa, although mostly insensitive to inhibitors of the mammalian proteins. Some of the PDEs have now been validated as promising drug targets. In the following manuscript, we will summarize the existing literature on cAMP and cGMP in protozoa: cyclases, PDEs and cyclic-nucleotide-dependent kinases.
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Affiliation(s)
- Matthew K Gould
- Biomedical Research Centre, Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, UK
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Nasereddin A, Schweynoch C, Schonian G, Jaffe CL. Characterization of Leishmania (Leishmania) tropica axenic amastigotes. Acta Trop 2010; 113:72-9. [PMID: 19782652 DOI: 10.1016/j.actatropica.2009.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 08/13/2009] [Accepted: 09/18/2009] [Indexed: 10/20/2022]
Abstract
Optimum conditions for generating Leishmania (Leishmania) tropica axenic amastigotes (AxA) in culture were determined, pH 5.5/36 degrees C, and the parasites characterized by different techniques, including light microscopy, macrophage infection, stage specific antigen expression and differential display. AxA were morphologically similar to amastigotes and 15.5-fold more infective than stationary phase promastigotes for mouse peritoneal macrophages. Western blotting with promastigote stage specific monoclonal antibodies to either lipophosphoglycan (T2) or a 60 kDa flagella antigen (F3) showed a dramatic decrease in antigen expression when AxA were compared to promastigotes. Similarly F3 gave strong immune fluorescent staining of the promastigote flagellum, but no fluorescence was detected when AxA were examined. Conversely, Western blotting with the amastigote specific monoclonal antibody (T16) showed that this antigen is more highly expressed in AxA than promastigotes. Differential display-PCR was used to identify several parasite genes showing stage specific expression. One gene selectively expressed by AxA was partially sequenced and identified as Leishmania (L.) tropicaamastin. Amastigote specific expression of this gene was further confirmed by reverse transcriptase-PCR (RT-PCR) using AxA and infected macrophages. No amastin expression was observed with promastigotes. Expression of the cysteine protease B (cpb) and protein kinase A catalytic isoform 1 subunit (pkac1) in promastigotes and AxA was also examined by RT-PCR. Pkac1 was strongly expressed by promastigotes, while cpb expression was only seen with AxA or infected macrophages. L. (L.) tropica AxA will prove useful for further studies on parasite differentiation and gene regulation, as well as for drug screening.
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Malki-Feldman L, Jaffe CL. Leishmania major: Effect of protein kinase A and phosphodiesterase activity on infectivity and proliferation of promastigotes. Exp Parasitol 2009; 123:39-44. [DOI: 10.1016/j.exppara.2009.05.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 04/30/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022]
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Shemarova IV. cAMP-dependent signal pathways in unicellular eukaryotes. Crit Rev Microbiol 2009; 35:23-42. [PMID: 19514907 DOI: 10.1080/10408410802645646] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The review summarizes current data about mechanisms of signal transduction with participation of cAMP (cyclic adenosine monophosphate) and elements of the complex cAMP-protein kinase A (PKA) signal pathway in unicellular eukaryotes. Conceptions of evolutionary origin of eukaryotic signal transduction systems are developed.
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Affiliation(s)
- Irina V Shemarova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia.
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Equinet L, Bapteste E, Thellier M, Ouarzane-Amara M, Vivarès CP, Desportes-Livage I, Doerig C. The genes encoding cAMP-dependent protein kinase catalytic subunit homologues of the microsporidia Encephalitozoon intestinalis and E. cuniculi: molecular characterisation and phylogenetic analysis. Parasitol Int 2005; 53:277-85. [PMID: 15464436 DOI: 10.1016/j.parint.2004.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2003] [Revised: 02/11/2004] [Accepted: 03/03/2004] [Indexed: 11/22/2022]
Abstract
A gene encoding a protein kinase was identified by homology-based PCR amplification in Encephalitozoon intestinalis, a microsporidian parasite pathogenic to humans, and its orthologue has been identified by database mining in the genome of the related species E. cuniculi, whose sequence has been recently published. Phylogenetic analysis revealed that the proteins encoded by these genes are homologues of the cAMP-dependent protein kinase catalytic subunits (PKAc). Southern blot analysis indicated that the EiPKAc gene is present in two copies in the E. intestinalis genome, whereas the E. cuniculi orthologue (EcPKAc) is a single copy gene. RT-PCR data showed that the EiPKAc gene is expressed in at least one of the intracellular stages during infection of the mammalian host cell by E. intestinalis.
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Affiliation(s)
- Leila Equinet
- INSERM U609, Wellcome Centre for Molecular Parasitology, University of Glasgow, 56 Dumbarton Road, Glasgow G11 6NU, Scotland, UK
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Galán-Caridad JM, Calabokis M, Uzcanga G, Aponte F, Bubis J. Identification of casein kinase 1, casein kinase 2, and cAMP-dependent protein kinase-like activities in Trypanosoma evansi. Mem Inst Oswaldo Cruz 2004; 99:845-54. [PMID: 15761601 DOI: 10.1590/s0074-02762004000800011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Trypanosoma evansi contains protein kinases capable of phosphorylating endogenous substrates with apparent molecular masses in the range between 20 and 205 kDa. The major phosphopolypeptide band, pp55, was predominantly localized in the particulate fraction. Anti-alpha and anti-beta tubulin monoclonal antibodies recognized pp55 by Western blot analyses, suggesting that this band corresponds to phosphorylated tubulin. Inhibition experiments in the presence of emodin, heparin, and 2,3-bisphosphoglycerate indicated that the parasite tubulin kinase was a casein kinase 2 (CK2)-like activity. GTP, which can be utilized instead of ATP by CK2, stimulated rather than inactivated the phosphorylation of tubulin in the parasite homogenate and particulate fraction. However, GTP inhibited the cytosolic CK2 responsible for phosphorylating soluble tubulin and other soluble substrates. Casein and two selective peptide substrates, P1 (RRKDLHDDEEDEAMSITA) for casein kinase (CK1) and P2 (RRRADDSDDDDD) for CK2, were recognized as substrates in T. evansi. While the enzymes present in the soluble fraction predominantly phosphorylated P1, P2 was preferentially labeled in the particulate fractions. These results demonstrated the existence of CK1-like and CK2-like activities primarily located in the parasite cytosolic and membranous fractions, respectively. Histone II-A and kemptide (LRRASVA) also behaved as suitable substrates, implying the existence of other Ser/Thr kinases in T. evansi. Cyclic AMP only increased the phosphorylation of histone II-A and kemptide in the cytosol, demonstrating the existence of soluble cAMP-dependent protein kinase-like activities in T. evansi. However, no endogenous substrates for this enzyme were identified in this fraction. Further evidences were obtained by using PKI (6-22), a reported inhibitor of the catalytic subunit of mammalian cAMP-dependent protein kinases, which specifically hindered the cAMP-dependent phosphorylation of histone II-A and kemptide in the parasite soluble fraction. Since the sum of the values obtained in the parasite cytosolic and particulate fractions were always higher than the values observed in the total T. evansi lysate, the kinase activities examined here appeared to be inhibited in the original extract.
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Affiliation(s)
- José Manuel Galán-Caridad
- Departamento de Biología Celular, Universidad Simón Bolívar, Apartado 89,000, Valle de Sartenejas, Baruta, Caracas 1081-A, Venezuela
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Campbell K, Popov V, Soong L. Identification and molecular characterization of a gene encoding a protective Leishmania amazonensis Trp-Asp (WD) protein. Infect Immun 2004; 72:2194-202. [PMID: 15039343 PMCID: PMC375213 DOI: 10.1128/iai.72.4.2194-2202.2004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2003] [Revised: 12/01/2003] [Accepted: 12/31/2003] [Indexed: 11/20/2022] Open
Abstract
Several Leishmania proteins have been identified and characterized in pursuit of understanding pathogenesis and protection in cutaneous leishmaniasis. In the present study, we utilized sera from infected BALB/c mice to screen a Leishmania amazonensis amastigote cDNA expression library and obtained the full-length gene that encodes a novel Trp-Asp (WD) protein designated LAWD (for Leishmania antigenic WD protein). The WD family of proteins mediates protein-protein interactions and coordinates the formation of protein complexes. The single-copy LAWD gene is transcribed as a approximately 3.1-kb mRNA in both promastigotes and amastigotes, with homologues being detected in several other Leishmania species. Immunoelectron microscopy revealed a predominant localization of the LAWD protein in the flagellar pocket. Analyses of sera from human patients with cutaneous and mucocutaneous leishmaniasis indicated that these individuals mounted significant humoral responses against LAWD. Given that recombinant LAWD protein elicited the production of high levels of gamma interferon, but no detectable levels of interleukin-10 (IL-10), in CD4(+) cells of L. amazonensis-infected mice, we further examined whether LAWD could elicit protective immunity. DNA vaccination with the LAWD and IL-12 genes significantly delayed lesion development, which correlated with a dramatic reduction in parasite burdens. Thus, we have successfully identified a promising vaccine candidate and antigenic vehicle to aid in the dissection of the complicated pathogenic immune response of L. amazonensis.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Protozoan/blood
- Antibodies, Protozoan/immunology
- Antigens, Protozoan/administration & dosage
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/genetics
- Antigens, Protozoan/immunology
- Aspartic Acid
- CD4-Positive T-Lymphocytes/immunology
- Cricetinae
- Female
- Humans
- Immunization
- Leishmania/genetics
- Leishmania/immunology
- Leishmania/metabolism
- Leishmaniasis, Cutaneous/immunology
- Leishmaniasis, Cutaneous/parasitology
- Mesocricetus
- Mice
- Mice, Inbred BALB C
- Molecular Sequence Data
- Protozoan Proteins/administration & dosage
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/immunology
- Protozoan Vaccines/administration & dosage
- Protozoan Vaccines/immunology
- Recombinant Proteins/administration & dosage
- Recombinant Proteins/immunology
- Sequence Analysis, DNA
- Tryptophan
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Affiliation(s)
- Kimberly Campbell
- Department of Microbiology and Immunology, Center for Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas 77555-1070, USA
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