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Polanco G, Scott NE, Lye LF, Beverley SM. Expanded Proteomic Survey of the Human Parasite Leishmania major Focusing on Changes in Null Mutants of the Golgi GDP-Mannose/Fucose/Arabinopyranose Transporter LPG2 and of the Mitochondrial Fucosyltransferase FUT1. Microbiol Spectr 2022; 10:e0305222. [PMID: 36394313 PMCID: PMC9769760 DOI: 10.1128/spectrum.03052-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/31/2022] [Indexed: 11/19/2022] Open
Abstract
The trypanosomatid protozoan parasite Leishmania has a significant impact on human health globally. Understanding the pathways associated with virulence within this significant pathogen is critical for identifying novel vaccination and chemotherapy targets. Within this study we leverage an ultradeep proteomic approach to improve our understanding of two virulence-associated genes in Leishmania, encoding the Golgi mannose/arabinopyranose/fucose nucleotide-sugar transporter (LPG2) and the mitochondrial fucosyltransferase (FUT1). Using deep peptide fractionation followed by complementary fragmentation approaches with higher-energy collisional dissociation (HCD) and electron transfer dissociation (ETD) allowed the identification of over 6,500 proteins, nearly doubling the experimentally known Leishmania major proteome. This deep proteomic analysis revealed significant quantitative differences in both Δlpg2- and Δfut1s mutants with FUT1-dependent changes linked to marked alterations within mitochondrion-associated proteins, while LPG2-dependent changes impacted many pathways, including the secretory pathway. While the FUT1 enzyme has been shown to fucosylate peptides in vitro, no evidence for protein fucosylation was identified within our ultradeep analysis, nor did we observe fucosylated glycans within Leishmania glycopeptides isolated using hydrophilic interaction liquid chromatography (HILIC) enrichment. This work provides a critical resource for the community on the observable Leishmania proteome as well as highlighting phenotypic changes associated with LPG2 or FUT1, ablation of which may guide the development of future therapeutics. IMPORTANCE Leishmania is a widespread trypanosomatid protozoan parasite of humans, with ~12 million cases currently, ranging from mild to fatal, and hundreds of millions asymptomatically infected. This work advances knowledge of the experimental proteome by nearly 2-fold, to more than 6,500 proteins and thus provides a great resource to investigators seeking to decode how this parasite is transmitted and causes disease and to identify new targets for therapeutic intervention. The ultradeep proteomics approach identified potential proteins underlying the "persistence-without-pathology" phenotype of mutants with deletion of the Golgi nucleotide transporter LPG2, showing many alterations and several candidates. Studies of a rare mutant with deletion of the mitochondrial fucosyltransferase FUT1 revealed changes underlying its strong mitochondrial dysfunction but did not reveal examples of fucosylation of either peptides or N-glycans. This suggests that this vital protein's elusive target(s) may be more complex than the methods used could detect or that this target may not be a protein but perhaps another glycoconjugate or glycolipid.
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Affiliation(s)
- Gloria Polanco
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Nichollas E. Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Lon F. Lye
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, USA
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2
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Kuhlmann FM, Key PN, Hickerson SM, Turk J, Hsu FF, Beverley SM. Inositol phosphorylceramide synthase null Leishmania are viable and virulent in animal infections where salvage of host sphingomyelin predominates. J Biol Chem 2022; 298:102522. [PMID: 36162499 PMCID: PMC9637897 DOI: 10.1016/j.jbc.2022.102522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 09/14/2022] [Accepted: 09/16/2022] [Indexed: 12/03/2022] Open
Abstract
Many pathogens synthesize inositol phosphorylceramide (IPC) as the major sphingolipid (SL), differing from the mammalian host where sphingomyelin (SM) or more complex SLs predominate. The divergence between IPC synthase and mammalian SL synthases has prompted interest as a potential drug target. However, in the trypanosomatid protozoan Leishmania, cultured insect stage promastigotes lack de novo SL synthesis (Δspt2-) and SLs survive and remain virulent, as infective amastigotes salvage host SLs and continue to produce IPC. To further understand the role of IPC, we generated null IPCS mutants in Leishmania major (Δipcs-). Unexpectedly and unlike fungi where IPCS is essential, Δipcs- was remarkably normal in culture and highly virulent in mouse infections. Both IPCS activity and IPC were absent in Δipcs- promastigotes and amastigotes, arguing against an alternative route of IPC synthesis. Notably, salvaged mammalian SM was highly abundant in purified amastigotes from both WT and Δipcs-, and salvaged SLs could be further metabolized into IPC. SM was about 7-fold more abundant than IPC in WT amastigotes, establishing that SM is the dominant amastigote SL, thereby rendering IPC partially redundant. These data suggest that SM salvage likely plays key roles in the survival and virulence of both WT and Δipcs- parasites in the infected host, confirmation of which will require the development of methods or mutants deficient in host SL/SM uptake in the future. Our findings call into question the suitability of IPCS as a target for chemotherapy, instead suggesting that approaches targeting SM/SL uptake or catabolism may warrant further emphasis.
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Affiliation(s)
- F. Matthew Kuhlmann
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA,Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Phillip N. Key
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Suzanne M. Hickerson
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - John Turk
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Fong-Fu Hsu
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA
| | - Stephen M. Beverley
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, Missouri, USA,For correspondence: Stephen M. Beverley
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Chen P, Yang J, Wu N, Han B, Kastelic JP, Gao J. Streptococcus lutetiensis Induces Autophagy via Oxidative Stress in Bovine Mammary Epithelial Cells. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:2549772. [PMID: 35178153 PMCID: PMC8843784 DOI: 10.1155/2022/2549772] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 01/11/2022] [Indexed: 02/07/2023]
Abstract
Streptococcus lutetiensis, an emerging pathogen causing bovine mastitis, has not been well characterized. We reported that S. lutetiensis was pathogenic both in vivo and in vitro and caused inflammatory reactions in the mammary gland. However, roles of autophagy and oxidative stress in the pathogenesis of S. lutetiensis-induced mastitis are unclear. In this study, an autophagy model of S. lutetiensis-infected bovine mammary epithelial cells (bMECs) was used to assess oxidative stress and autophagy flux. Expressions of Beclin1, light chain 3II, and Sequestosome 1/p62 were elevated in bMECs after S. lutetiensis infection. In addition, autophagosome and lysosome formation confirmed autophagy occurred. Based on LysoTracker Red and acridine orange, lysosome degradation was blocked, and lower expressions of lysosomal-associated membrane protein 2, cathepsins D, and cathepsins L confirmed lysosomal damage. Concurrently, the nuclear factor erythroid 2-related factor 2 (Nrf2), kelch-like ECH-associated protein 1 (Keap1), heme oxygenase 1 (HO1), and NAD (P)H: quinone oxidoreductase 1 (NQO1), and basilic proteins associated with the Nrf2/Keap1 signaling pathway, were detected. Decreased keap1 and increased Nrf2, HO1, NQO1, and reactive oxygen species (ROS) indicated increased oxidative stress. Treatment with N-Acetyl-L-cysteine (NAC), an ROS inhibitor, decreased both oxidative stress and autophagy. Therefore, we concluded that S. lutetiensis caused intracellular oxidative stress and autophagy in bMECs. In addition, crosstalk between autophagy and oxidative stress affected the autophagic flux and blocked downstream autophagy. The Nrf2-keap1-p62 pathway participated in this process, with ROS acting upstream of these effects, interfering with normal cell functions.
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Affiliation(s)
- Peng Chen
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Jingyue Yang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Naiwen Wu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - Bo Han
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
| | - John P. Kastelic
- Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N 4N1
| | - Jian Gao
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China
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Geng N, Wang X, Yu X, Wang R, Zhu Y, Zhang M, Liu J, Liu Y. Staphylococcus aureus Avoids Autophagy Clearance of Bovine Mammary Epithelial Cells by Impairing Lysosomal Function. Front Immunol 2020; 11:746. [PMID: 32431700 PMCID: PMC7214833 DOI: 10.3389/fimmu.2020.00746] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/01/2020] [Indexed: 12/26/2022] Open
Abstract
In dairy herds, mastitis caused by Staphylococcus aureus is difficult to completely cure on the account that S. aureus can invade bovine mammary epithelial cells (BMECs) and result in persistent infection in the mammary gland. Recent studies have demonstrated that autophagy can participate in cell homeostasis by eliminating intracellular microorganisms. The aim of the study was to investigate why S. aureus can evade autophagy clearance and survive in BMECs. The intracellular infection model was first constructed; then, the bacteria in autophagosome was detected by transmission electron microscopy. The autophagy flux induced by the S. aureus was also evaluated by immunoblot analysis and fluorescent labeling method for autophagy marker protein LC3. In addition, lysosomal alkalization and degradation ability were assessed using confocal microscopy. Results showed that, after infection, a double-layer membrane structure around the S. aureus was observed in BMECs, indicating that autophagy occurred. The change in autophagy marker protein and fluorescent labeling of autophagosome also confirmed autophagy. However, as time prolonged, the autophagy flux was markedly inhibited, leading to obvious autophagosome accumulation. At the same time, the lysosomal alkalization and degradation ability of BMECs were impaired. Collectively, these results indicated that S. aureus could escape autophagic degradation by inhibiting autophagy flux and damaging lysosomal function after invading BMECs.
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Affiliation(s)
- Na Geng
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Xiaozhou Wang
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Xiaohui Yu
- China Animal Health and Epidemiology Center, Qingdao, China
| | - Run Wang
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Yiran Zhu
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Meihua Zhang
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Jianzhu Liu
- Research Center for Animal Disease Control Engineering, Shandong Agricultural University, Tai'an, China
| | - Yongxia Liu
- College of Veterinary Medicine, Shandong Agricultural University, Tai'an, China
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Activity of Chitosan and Its Derivatives against Leishmania major and Leishmania mexicana In Vitro. Antimicrob Agents Chemother 2020; 64:AAC.01772-19. [PMID: 31871082 PMCID: PMC7038302 DOI: 10.1128/aac.01772-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/08/2019] [Indexed: 12/18/2022] Open
Abstract
There is an urgent need for safe, efficacious, affordable, and field-adapted drugs for the treatment of cutaneous leishmaniasis, which newly affects around 1.5 million people worldwide annually. Chitosan, a biodegradable cationic polysaccharide, has previously been reported to have antimicrobial, antileishmanial, and immunostimulatory activities. There is an urgent need for safe, efficacious, affordable, and field-adapted drugs for the treatment of cutaneous leishmaniasis, which newly affects around 1.5 million people worldwide annually. Chitosan, a biodegradable cationic polysaccharide, has previously been reported to have antimicrobial, antileishmanial, and immunostimulatory activities. We investigated the in vitro activity of chitosan and several of its derivatives and showed that the pH of the culture medium plays a critical role in antileishmanial activity of chitosan against both extracellular promastigotes and intracellular amastigotes of Leishmania major and Leishmania mexicana. Chitosan and its derivatives were approximately 7 to 20 times more active at pH 6.5 than at pH 7.5, with high-molecular-weight chitosan being the most potent. High-molecular-weight chitosan stimulated the production of nitric oxide and reactive oxygen species by uninfected and Leishmania-infected macrophages in a time- and dose-dependent manner at pH 6.5. Despite the in vitro activation of bone marrow macrophages by chitosan to produce nitric oxide and reactive oxygen species, we showed that the antileishmanial activity of chitosan was not mediated by these metabolites. Finally, we showed that rhodamine-labeled chitosan is taken up by pinocytosis and accumulates in the parasitophorous vacuole of Leishmania-infected macrophages.
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Mukherjee S, Xu W, Hsu FF, Patel J, Huang J, Zhang K. Sterol methyltransferase is required for optimal mitochondrial function and virulence in Leishmania major. Mol Microbiol 2019; 111:65-81. [PMID: 30260041 PMCID: PMC6351164 DOI: 10.1111/mmi.14139] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2018] [Indexed: 12/24/2022]
Abstract
Limited knowledge on the exact functions of ergostane-based sterols has hampered the application of sterol synthesis inhibitors against trypanosomatid parasites. Sterol methyltransferase (SMT) is directly involved in the synthesis of parasite-specific C24-methylated sterols, including ergosterol and 5-dehydroepisterol. While pharmacological studies hint at its potential as a drug target against trypanosomatids, direct evidence for the cellular function and essentiality of SMT is lacking. Here, we characterized the SMT knockout mutants and their complemented strains in Leishmania major, the causative agent for cutaneous leishmaniasis. Deletion of SMT alleles led to a complete loss of C24-methylated sterols, which were replaced by cholestane-based sterols. SMT-null mutants were fully viable and replicative in culture but showed increased sensitivity to sphingolipid synthesis inhibition. They were not particularly vulnerable to heat, acidic pH, nitrosative or oxidative stress, yet exhibited high mitochondrial membrane potential and increased superoxide generation indicating altered physiology of the mitochondria. Despite possessing high levels of GPI-anchored glycoconjugates, SMT-null mutants showed significantly attenuated virulence in mice. In total, our study reveals that the biosynthesis of ergostane-based sterols is crucial for the proper function of mitochondria and the proliferation of Leishmania parasites in mammals.
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Affiliation(s)
- Sumit Mukherjee
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Wei Xu
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
- Current address: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jigesh Patel
- Department of Physics, Texas Tech University, Lubbock, TX 79409, USA
| | - Juyang Huang
- Department of Physics, Texas Tech University, Lubbock, TX 79409, USA
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
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7
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Abstract
The kinetoplastid parasite Trypanosoma brucei causes African trypanosomiasis in both humans and animals. Infections place a significant health and economic burden on developing nations in sub-Saharan Africa, but few effective anti-parasitic treatments are currently available. Hence, there is an urgent need to identify new leads for drug development. The T. brucei neutral sphingomyelinase (TbnSMase) was previously established as essential to parasite survival, consequently being identified as a potential drug target. This enzyme may catalyse the single route to sphingolipid catabolism outside the T. brucei lysosome. To obtain new insight into parasite sphingolipid catabolism, the substrate specificity of TbnSMase was investigated using electrospray ionization tandem mass spectrometry (ESI-MS/MS). Recombinant TbnSMase was shown to degrade sphingomyelin, inositol-phosphoceramide and ethanolamine-phosphoceramide sphingolipid substrates, consistent with the sphingolipid complement of the parasites. TbnSMase also catabolized ceramide-1-phosphate, but was inactive towards sphingosine-1-phosphate. The broad-range specificity of this enzyme towards sphingolipid species is a unique feature of TbnSMase. Additionally, ESI-MS/MS analysis revealed previously uncharacterized activity towards lyso-phosphatidylcholine despite the enzyme's inability to degrade phosphatidylcholine. Collectively, these data underline the enzyme's importance in choline homoeostasis and the turnover of sphingolipids in T. brucei.
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Bhat OM, Yuan X, Li G, Lee R, Li PL. Sphingolipids and Redox Signaling in Renal Regulation and Chronic Kidney Diseases. Antioxid Redox Signal 2018; 28:1008-1026. [PMID: 29121774 PMCID: PMC5849286 DOI: 10.1089/ars.2017.7129] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 10/30/2017] [Accepted: 11/04/2017] [Indexed: 01/04/2023]
Abstract
Significance: Sphingolipids play critical roles in the membrane biology and intracellular signaling events that influence cellular behavior and function. Our review focuses on the cellular mechanisms and functional relevance of the cross talk between sphingolipids and redox signaling, which may be critically implicated in the pathogenesis of different renal diseases. Recent Advances: Reactive oxygen species (ROS) and sphingolipids can regulate cellular redox homeostasis through the regulation of NADPH oxidase, mitochondrial integrity, nitric oxide synthase (NOS), and antioxidant enzymes. Over the last two decades, there have been significant advancements in the field of sphingolipid research, and it was in 2010 for the first time that sphingolipid receptor modulator was exploited as a therapeutic in humans. The cross talk of sphingolipids with redox signaling pathways becomes an important mechanism in the development of many different diseases such as renal diseases. Critical Issues: The critical issues to be addressed in this review are how sphingolipids interact with the redox signaling pathway to regulate renal function and even result in chronic kidney diseases. Ceramide, sphingosine, and sphingosine-1-phosphate (S1P) as main signaling sphingolipids are discussed in more detail. Future Directions: Although sphingolipids and ROS may mediate or modulate cellular responses to physiological and pathological stimuli, more translational studies and mechanistic pursuit in a tissue- or cell-specific way are needed to enhance our understanding of this important topic and to develop effective therapeutic strategies to treat diseases associated with redox signaling and sphingolipid cross talk. Antioxid. Redox Signal. 28, 1008-1026.
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Affiliation(s)
- Owais M Bhat
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Xinxu Yuan
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Guangbi Li
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - RaMi Lee
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Pin-Lan Li
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
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Xu W, Mukherjee S, Ning Y, Hsu FF, Zhang K. Cyclopropane fatty acid synthesis affects cell shape and acid resistance in Leishmania mexicana. Int J Parasitol 2017; 48:245-256. [PMID: 29180119 DOI: 10.1016/j.ijpara.2017.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 09/15/2017] [Indexed: 10/18/2022]
Abstract
Cyclopropane fatty acid synthase (CFAS) catalyzes the transfer of a methylene group from S-adenosyl methionine to an unsaturated fatty acid, generating a cyclopropane fatty acid (CFA). The gene encoding CFAS is present in many bacteria and several Leishmania spp. including Leishmania mexicana, Leishmania infantum and Leishmania braziliensis. In this study, we characterised the CFAS-null and -overexpression mutants in L. mexicana, the causative agent for cutaneous leishmaniasis in Mexico and central America. Our data indicate that L. mexicana CFAS modifies the fatty acid chain of plasmenylethanolamine (PME), the dominant class of ethanolamine glycerophospholipids in Leishmania, generating CFA-PME. While the endogenous level of CFA-PME is extremely low in wild type L. mexicana, overexpression of CFAS results in a significant increase. CFAS-null mutants (cfas-) exhibit altered cell shape, increased sensitivity to acidic pH, and aberrant growth in serum-free media. In addition, the CFAS protein is preferentially expressed during the proliferative stage of L. mexicana and is required for the cell membrane targeting of lipophosphoglycan. Finally, the maturation and localization of CFAS protein are dependent upon the downstream sequence of the CFAS coding region. Without the downstream sequence, the mis-localised CFAS protein cannot fully rescue the defects of cfas-. Our data suggest that CFA modification of phospholipids can significantly affect the parasite's response to certain adverse conditions. These findings are distinct from the roles of CFAS in L. infantum, highlighting the functional divergence in lipid modification among Leishmania spp.
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Affiliation(s)
- Wei Xu
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Sumit Mukherjee
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Yu Ning
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Fong-Fu Hsu
- Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid research, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA.
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Mandlik V, Singh S. Integrative approaches for identification of novel ISCL inhibitors in Leishmaniasis: A computational insight into the structure. GENE REPORTS 2016. [DOI: 10.1016/j.genrep.2016.05.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Pawlowic M, Hsu FF, Moitra S, Biyani N, Zhang K. Plasmenylethanolamine synthesis in Leishmania major. Mol Microbiol 2016; 101:238-49. [PMID: 27062077 PMCID: PMC4935589 DOI: 10.1111/mmi.13387] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/28/2016] [Indexed: 02/06/2023]
Abstract
Ethanolamine glycerophospholipids are ubiquitous cell membrane components. Trypanosomatid parasites of the genus Leishmania synthesize the majority of their ethanolamine glycerophospholipids as 1-O-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine or plasmenylethanolamine (PME) through the Kennedy pathway. PME is a subtype of ether phospholipids also known as ethanolamine plasmalogen whose functions are not well characterized. In this study, we investigated the role of PME synthesis in Leishmania major through the characterization of an ethanolamine phosphotransferase (EPT) mutant. EPT-null parasites are largely devoid of PME and fully viable in regular medium but fail to proliferate in the absence of fetal bovine serum. They exhibit significant abnormalities in the synthesis and localization of GPI-anchored surface molecules. EPT-null mutants also show attenuated virulence in BALB/c mice. Furthermore, in addition to PME synthesis, ethanolamine also contributes to the production of phosphatidylcholine, the most abundant class of lipids in Leishmania. Together, these findings suggest that ethanolamine production is likely required for Leishmania promastigotes to generate bulk phospholipids, to handle stress, and to control the expression of membrane bound virulence factors.
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Affiliation(s)
- Mattie Pawlowic
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Fong-fu Hsu
- Department of Internal Medicine, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110, USA
| | - Samrat Moitra
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Neha Biyani
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
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12
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Dillon LAL, Suresh R, Okrah K, Corrada Bravo H, Mosser DM, El-Sayed NM. Simultaneous transcriptional profiling of Leishmania major and its murine macrophage host cell reveals insights into host-pathogen interactions. BMC Genomics 2015; 16:1108. [PMID: 26715493 PMCID: PMC4696162 DOI: 10.1186/s12864-015-2237-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/24/2015] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Parasites of the genus Leishmania are the causative agents of leishmaniasis, a group of diseases that range in manifestations from skin lesions to fatal visceral disease. The life cycle of Leishmania parasites is split between its insect vector and its mammalian host, where it resides primarily inside of macrophages. Once intracellular, Leishmania parasites must evade or deactivate the host's innate and adaptive immune responses in order to survive and replicate. RESULTS We performed transcriptome profiling using RNA-seq to simultaneously identify global changes in murine macrophage and L. major gene expression as the parasite entered and persisted within murine macrophages during the first 72 h of an infection. Differential gene expression, pathway, and gene ontology analyses enabled us to identify modulations in host and parasite responses during an infection. The most substantial and dynamic gene expression responses by both macrophage and parasite were observed during early infection. Murine genes related to both pro- and anti-inflammatory immune responses and glycolysis were substantially upregulated and genes related to lipid metabolism, biogenesis, and Fc gamma receptor-mediated phagocytosis were downregulated. Upregulated parasite genes included those aimed at mitigating the effects of an oxidative response by the host immune system while downregulated genes were related to translation, cell signaling, fatty acid biosynthesis, and flagellum structure. CONCLUSIONS The gene expression patterns identified in this work yield signatures that characterize multiple developmental stages of L. major parasites and the coordinated response of Leishmania-infected macrophages in the real-time setting of a dual biological system. This comprehensive dataset offers a clearer and more sensitive picture of the interplay between host and parasite during intracellular infection, providing additional insights into how pathogens are able to evade host defenses and modulate the biological functions of the cell in order to survive in the mammalian environment.
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Affiliation(s)
- Laura A L Dillon
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA. .,Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD, 20742, USA.
| | - Rahul Suresh
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA.
| | - Kwame Okrah
- Department of Mathematics, University of Maryland, College Park, MD, 20742, USA.
| | - Hector Corrada Bravo
- Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD, 20742, USA. .,Department of Computer Science, University of Maryland, College Park, MD, 20742, USA.
| | - David M Mosser
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA.
| | - Najib M El-Sayed
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA. .,Center for Bioinformatics and Computational Biology, University of Maryland, College Park, MD, 20742, USA. .,Present Address: 3128 Bioscience Research Bldg., University of Maryland, College Park, MD, 20742, USA.
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13
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Xu W, Hsu FF, Baykal E, Huang J, Zhang K. Sterol biosynthesis is required for heat resistance but not extracellular survival in leishmania. PLoS Pathog 2014; 10:e1004427. [PMID: 25340392 PMCID: PMC4207814 DOI: 10.1371/journal.ppat.1004427] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 08/27/2014] [Indexed: 12/25/2022] Open
Abstract
Sterol biosynthesis is a crucial pathway in eukaryotes leading to the production of cholesterol in animals and various C24-alkyl sterols (ergostane-based sterols) in fungi, plants, and trypanosomatid protozoa. Sterols are important membrane components and precursors for the synthesis of powerful bioactive molecules, including steroid hormones in mammals. Their functions in pathogenic protozoa are not well characterized, which limits the development of sterol synthesis inhibitors as drugs. Here we investigated the role of sterol C14α-demethylase (C14DM) in Leishmania parasites. C14DM is a cytochrome P450 enzyme and the primary target of azole drugs. In Leishmania, genetic or chemical inactivation of C14DM led to a complete loss of ergostane-based sterols and accumulation of 14-methylated sterols. Despite the drastic change in lipid composition, C14DM-null mutants (c14dm(-)) were surprisingly viable and replicative in culture. They did exhibit remarkable defects including increased membrane fluidity, failure to maintain detergent resistant membrane fraction, and hypersensitivity to heat stress. These c14dm(-) mutants showed severely reduced virulence in mice but were highly resistant to itraconazole and amphotericin B, two drugs targeting sterol synthesis. Our findings suggest that the accumulation of toxic sterol intermediates in c14dm(-) causes strong membrane perturbation and significant vulnerability to stress. The new knowledge may help improve the efficacy of current drugs against pathogenic protozoa by exploiting the fitness loss associated with drug resistance.
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Affiliation(s)
- Wei Xu
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Fong-Fu Hsu
- Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Eda Baykal
- Department of Physics, Texas Tech University, Lubbock, Texas, United States of America
| | - Juyang Huang
- Department of Physics, Texas Tech University, Lubbock, Texas, United States of America
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
- * E-mail:
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Haouas N, Remadi L, Chaara D, Chargui N, Dabghi R, Jbeniani H, Babba H, Ravel C. Unexpected co-detection of promastigote and amastigote Leishmania forms in a human cutaneous lesion: implications for leishmaniasis physiopathology and treatment. Diagn Microbiol Infect Dis 2014; 81:18-20. [PMID: 25312011 DOI: 10.1016/j.diagmicrobio.2014.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/09/2014] [Accepted: 09/15/2014] [Indexed: 10/24/2022]
Abstract
Cutaneous leishmaniasis pathogenicity depends on the survival and replication of the parasitic protozoa in the form of non-motile amastigotes inside macrophages. Here, we report the unprecedented observation of both Leishmania major amastigote and promastigote forms (the latter is normally detected only in the mid gut of the insect vector or in vitro culture) in a cutaneous lesion of a 6-year-old boy. This finding suggests that modifications of the skin lesion environment, such as maceration and changes in pH or temperature, could promote the in situ transformation of Leishmania amastigotes into promastigotes. This observation raises questions about the physiopathology of cutaneous leishmaniasis and the influence of micro-environmental changes on the efficiency of topical treatments.
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Affiliation(s)
- Najoua Haouas
- Laboratoire de Parasitologie-Mycologie Médicale et Moléculaire (code LR12ES08), Département de Biologie Clinique B, Faculté de Pharmacie, Université de Monastir, Tunisia.
| | - Latifa Remadi
- Laboratoire de Parasitologie-Mycologie Médicale et Moléculaire (code LR12ES08), Département de Biologie Clinique B, Faculté de Pharmacie, Université de Monastir, Tunisia
| | - Dhekra Chaara
- Laboratoire de Parasitologie-Mycologie Médicale et Moléculaire (code LR12ES08), Département de Biologie Clinique B, Faculté de Pharmacie, Université de Monastir, Tunisia
| | - Najla Chargui
- Laboratoire de Parasitologie-Mycologie Médicale et Moléculaire (code LR12ES08), Département de Biologie Clinique B, Faculté de Pharmacie, Université de Monastir, Tunisia
| | | | - Henda Jbeniani
- Centre d'Hygiène et des Soins de Santé de Base de Kairouan, Tunisia
| | - Hamouda Babba
- Laboratoire de Parasitologie-Mycologie Médicale et Moléculaire (code LR12ES08), Département de Biologie Clinique B, Faculté de Pharmacie, Université de Monastir, Tunisia
| | - Christophe Ravel
- French Reference Centre on Leishmaniasis, UMR5290 MIVEGEC, University of Montpellier, Department of Parasitology, Montpellier, France
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15
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Zhang O, Hsu FF, Xu W, Pawlowic M, Zhang K. Sphingosine kinase A is a pleiotropic and essential enzyme for Leishmania survival and virulence. Mol Microbiol 2013; 90:489-501. [PMID: 23980754 PMCID: PMC3938578 DOI: 10.1111/mmi.12378] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2013] [Indexed: 01/05/2023]
Abstract
Sphingosine kinase is a key enzyme in sphingolipid metabolism, catalysing the conversion of sphingosine or dihydrosphingosine into sphingosine-1-phosphate or dihydrosphingosine-1-phosphate respectively. In mammals, sphingosine-1-phosphate is a powerful signalling molecule regulating cell growth, differentiation, apoptosis and immunity. Functions of sphingosine kinase or sphingosine-1-phosphate in pathogenic protozoans are virtually unknown. While most organisms possess two closely related sphingosine kinases, only one sphingosine kinase homologue (SKa) can be identified in Leishmania, which are vector-borne protozoan parasites responsible for leishmaniasis. Leishmania SKa is a large, cytoplasmic enzyme capable of phosphorylating both sphingosine and dihydrosphingosine. Remarkably, deletion of SKa leads to catastrophic defects in both the insect stage and mammalian stage of Leishmania parasites. Genetic and biochemical analyses demonstrate that proper expression of SKa is essential for Leishmania parasites to remove toxic metabolites, to survive stressful conditions, and to cause disease in mice. Therefore, SKa is a pleiotropic enzyme with vital roles throughout the life cycle of Leishmania. The essentiality of SKa and its apparent divergence from mammalian counterparts suggests that this enzyme can be selectively targeted to reduce Leishmania infection.
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Affiliation(s)
- Ou Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Fong-Fu Hsu
- Department of Internal Medicine, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110, USA
| | - Wei Xu
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Mattie Pawlowic
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
| | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
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16
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Mou Z, Muleme HM, Liu D, Jia P, Okwor IB, Kuriakose SM, Beverley SM, Uzonna JE. Parasite-derived arginase influences secondary anti-Leishmania immunity by regulating programmed cell death-1-mediated CD4+ T cell exhaustion. THE JOURNAL OF IMMUNOLOGY 2013; 190:3380-9. [PMID: 23460745 DOI: 10.4049/jimmunol.1202537] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The breakdown of L-arginine to ornithine and urea by host arginase supports Leishmania proliferation in macrophages. Studies using arginase-null mutants show that Leishmania-derived arginase plays an important role in disease pathogenesis. We investigated the role of parasite-derived arginase in secondary (memory) anti-Leishmania immunity in the resistant C57BL/6 mice. We found that C57BL/6 mice infected with arginase-deficient (arg(-)) L. major failed to completely resolve their lesion and maintained chronic pathology after 16 wk, a time when the lesion induced by wild-type L. major is completely resolved. This chronic disease was associated with impaired Ag-specific proliferation and IFN-γ production, a concomitant increase in programmed cell death-1 (PD-1) expression on CD4(+) T cells, and failure to induce protection against secondary L. major challenge. Treatment with anti-PD-1 mAb restored T cell proliferation and IFN-γ production in vitro and led to complete resolution of chronic lesion in arg(-) L. major-infected mice. These results show that infection with arg(-) L. major results in chronic disease due in part to PD-1-mediated clonal exhaustion of T cells, suggesting that parasite-derived arginase contributes to the overall quality of the host immune response and subsequent disease outcome in L. major-infected mice. They also indicate that persistent parasites alone do not regulate the quality of secondary anti-Leishmania immunity in mice and that the quality of the primary immune response may be playing a hitherto unrecognized dominant role in this process.
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Affiliation(s)
- Zhirong Mou
- Department of Immunology, University of Manitoba, Winnipeg, Manitoba R3E 0T5, Canada
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17
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Sphingolipid degradation in Leishmania (Leishmania) amazonensis. PLoS Negl Trop Dis 2012; 6:e1944. [PMID: 23285302 PMCID: PMC3527339 DOI: 10.1371/journal.pntd.0001944] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Accepted: 10/24/2012] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Human leishmaniasis is caused by more than 20 Leishmania species and has a wide range of symptoms. Our recent studies have demonstrated the essential role of sphingolipid degradation in the virulence of Leishmania (Leishmania) major, a species responsible for localized cutaneous leishmaniasis in the Old World. In this study, we investigated the function of sphingolipid degradation in Leishmania (Leishmania) amazonensis, an etiological agent of localized and diffuse cutaneous leishmaniasis in South America. METHODOLOGY/PRINCIPAL FINDINGS First, we identified the enzyme LaISCL which is responsible for sphingolipid degradation in L. amazonensis. Primarily localized in the mitochondrion, LaISCL shows increased expression as promastigotes progress from replicative log phase to non-replicative stationary phase. To study its function, null mutants of LaISCL (Laiscl(-)) were generated by targeted gene deletion and complemented through episomal gene add-back. In culture, loss of LaISCL leads to hypersensitivity to acidic pH and poor survival in murine macrophages. In animals, Laiscl(-) mutants exhibit severely attenuated virulence towards C57BL6 mice but are fully infective towards BALB/c mice. This is drastically different from wild type L. amazonensis which cause severe pathology in both BALB/c and C57BL 6 mice. CONCLUSIONS/SIGNIFICANCE A single enzyme LaISCL is responsible for the turnover of sphingolipids in L. amazonensis. LaISCL exhibits similar expression profile and biochemical property as its ortholog in L. major. Deletion of LaISCL reduces the virulence of L. amazonensis and the outcome of Laiscl(-)-infection is highly dependent on the host's genetic background. Therefore, compared to L. major, the role of sphingolipid degradation in virulence is substantially different in L. amazonensis. Future studies may reveal whether sphingolipid degradation is required for L. amazonensis to cause diffuse cutaneous infections in humans.
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18
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Pawlowic MC, Zhang K. Leishmania parasites possess a platelet-activating factor acetylhydrolase important for virulence. Mol Biochem Parasitol 2012; 186:11-20. [PMID: 22954769 DOI: 10.1016/j.molbiopara.2012.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 08/20/2012] [Accepted: 08/21/2012] [Indexed: 01/03/2023]
Abstract
Leishmania parasites are intracellular protozoans capable of salvaging and remodeling lipids from the host. To understand the role of lipid metabolism in Leishmania virulence, it is necessary to characterize the enzymes involved in the uptake and turnover of phospholipids. This study focuses on a putative phospholipase A2 (PLA2)/platelet-activating factor acetylhydrolase (PAF-AH) in Leishmania major. In mammals, PAF-AH is a subgroup of PLA2 catalyzing the hydrolysis/inactivation of platelet-activating factor (PAF), a potent mediator of many leukocyte functions. By immunofluorescence microscopy, L. major PLA2/PAF-AH is predominantly localized in the ER. While wild type L. major parasites are able to hydrolyze PAF, this activity is completely absent in the PLA2/PAF-AH-null mutants. Meanwhile, deletion of PLA2/PAF-AH had no significant effect on the turnover of common glycerophospholipids such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylglycerol. PLA2/PAF-AH is not required for the growth of L. major parasites in culture, or the production of GPI-anchored virulence factors. Nonetheless, it does play a key role in the mammalian host as the PLA2/PAF-AH null mutants exhibit attenuated virulence in BALB/c mice. In conclusion, these data suggest that Leishmania parasites possess a functional PAF-AH and the degradation of PAF or PAF-like lipids is an important step in infection.
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Affiliation(s)
- Mattie C Pawlowic
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA
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Soong L. Subversion and Utilization of Host Innate Defense by Leishmania amazonensis. Front Immunol 2012; 3:58. [PMID: 22566939 PMCID: PMC3342205 DOI: 10.3389/fimmu.2012.00058] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 03/06/2012] [Indexed: 01/07/2023] Open
Abstract
Infection with Leishmania amazonensis and other members of the Leishmania mexicana complex can lead to diverse clinical manifestations, some of which are relatively difficult to control, even with standard chemotherapy. Diffuse cutaneous leishmaniasis (CL) is a rare but severe form, and its clinical hallmark is excessive parasitic growth in infected cells accompanied by profound impairments in host immune responses to the parasites. Since these parasites also cause non-healing CL in most inbred strains of mice, these animals are valuable models for dissecting the mechanisms of persistent infection and disease pathogenesis. In comparison to other Leishmania species, L. amazonensis infections are most remarkable for their ability to repress the activation and effector functions of macrophages, dendritic cells, and CD4(+) T cells, implying discrete mechanisms at work. In addition to this multilateral suppression of host innate and adaptive immunity, the activation of types I and II interferon-mediated responses and autophagic/lipid metabolic pathways actually promotes rather than restrains L. amazonensis infection. These seemingly contradictory findings reflect the remarkable adaptation of the parasites to the ancient defense machinery of the host, as well as the complex parasite-host interactions at different stages of infection, which collectively contribute to non-healing leishmaniasis in the New World. This review article highlights new evidence that reveals the strategies utilized by L. amazonensis parasites to subvert or modulate host innate defense machinery in neutrophils and macrophages, as well as the regulatory roles of host innate responses in promoting parasite survival and replication within the huge parasitophorous vacuoles. A better understanding of unique features in host responses to these parasites at early and late stages of infection is important for the rational design of control strategies for non-healing leishmaniasis.
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Affiliation(s)
- Lynn Soong
- Center for Tropical Diseases, Sealy Center for Vaccine Development, Department of Microbiology and Immunology, The University of Texas Medical Branch Galveston, TX, USA
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20
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Sphingolipid and ceramide homeostasis: potential therapeutic targets. Biochem Res Int 2012; 2012:248135. [PMID: 22400113 PMCID: PMC3286894 DOI: 10.1155/2012/248135] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Accepted: 10/20/2011] [Indexed: 12/26/2022] Open
Abstract
Sphingolipids are ubiquitous in eukaryotic cells where they have been attributed a plethora of functions from the formation of structural domains to polarized cellular trafficking and signal transduction. Recent research has identified and characterised many of the key enzymes involved in sphingolipid metabolism and this has led to a heightened interest in the possibility of targeting these processes for therapies against cancers, Alzheimer's disease, and numerous important human pathogens. In this paper we outline the major pathways in eukaryotic sphingolipid metabolism and discuss these in relation to disease and therapy for both chronic and infectious conditions.
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Zhang O, Xu W, Balakrishna Pillai A, Zhang K. Developmentally regulated sphingolipid degradation in Leishmania major. PLoS One 2012; 7:e31059. [PMID: 22299050 PMCID: PMC3267774 DOI: 10.1371/journal.pone.0031059] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 01/01/2012] [Indexed: 12/22/2022] Open
Abstract
Leishmania parasites alternate between extracellular promastigotes in sandflies and intracellular amastigotes in mammals. These protozoans acquire sphingolipids (SLs) through de novo synthesis (to produce inositol phosphorylceramide) and salvage (to obtain sphingomyelin from the host). A single ISCL (Inositol phosphoSphingolipid phospholipase C-Like) enzyme is responsible for the degradation of both inositol phosphorylceramide (the IPC hydrolase or IPCase activity) and sphingomyelin (the SMase activity). Recent studies of a L. major ISCL-null mutant (iscl−) indicate that SL degradation is required for promastigote survival in stationary phase, especially under acidic pH. ISCL is also essential for L. major proliferation in mammals. To further understand the role of ISCL in Leishmania growth and virulence, we introduced a sole IPCase or a sole SMase into the iscl− mutant. Results showed that restoration of IPCase only complemented the acid resistance defect in iscl− promastigotes and improved their survival in macrophages, but failed to recover virulence in mice. In contrast, a sole SMase fully restored parasite infectivity in mice but was unable to reverse the promastigote defects in iscl−. These findings suggest that SL degradation in Leishmania possesses separate roles in different stages: while the IPCase activity is important for promastigote survival and acid tolerance, the SMase activity is required for amastigote proliferation in mammals. Consistent with these findings, ISCL was preferentially expressed in stationary phase promastigotes and amastigotes. Together, our results indicate that SL degradation by Leishmania is critical for parasites to establish and sustain infection in the mammalian host.
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Affiliation(s)
- Ou Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - Wei Xu
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | | | - Kai Zhang
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
- * E-mail:
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Endocytosis and Sphingolipid Scavenging in Leishmania mexicana Amastigotes. Biochem Res Int 2011; 2012:691363. [PMID: 21941657 PMCID: PMC3177366 DOI: 10.1155/2012/691363] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 07/18/2011] [Accepted: 07/22/2011] [Indexed: 01/03/2023] Open
Abstract
Leishmania species are the causative agents of the leishmaniases, a spectrum of neglected tropical diseases. Amastigote stage parasites exist within macrophages and scavenge host factors for survival, for example, Leishmania species utilise host sphingolipid for synthesis of complex sphingolipid. In this study L. mexicana endocytosis was shown to be significantly upregulated in amastigotes, indicating that sphingolipid scavenging may be enhanced. However, inhibition of host sphingolipid biosynthesis had no significant effect on amastigote proliferation within a macrophage cell line. In addition, infection itself did not directly influence host biosynthesis. Notably, in contrast to L. major, L. mexicana amastigotes are indicated to possess a complete biosynthetic pathway suggesting that scavenged sphingolipids may be nonessential for proliferation. This suggested that Old and New World species differ in their interactions with the macrophage host. This will need to be considered when targeting the Leishmania sphingolipid biosynthetic pathway with novel therapeutics.
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