bims-toxgon 2024-01-07 papers

bims-toxgon

Biomed News

on Toxoplasma gondii metabolism

Issue of 2024–01–07
thirteen papers selected by
Lakesh Kumar, BITS Pilani

The initiation and early development of the tubulin-containing cytoskeleton in the human parasite Toxoplasma gondii.
Editorial overview: Modern approaches to dissect host-pathogen interactions.
Toxoplasma gondii surface antigen 1 (SAG1) interacts in vitro with host cell receptor for activated C kinase 1 (RACK1).
Toxoplasma membrane inositol phospholipid binding protein TgREMIND is essential for secretory organelle function and host infection.
Toxoplasma protein export and effector function.
Host E3 ubiquitin ligase ITCH mediates Toxoplasma gondii effector GRA35-triggered NLRP1 inflammasome activation and cell-autonomous immunity.
Biomechanics of parasite migration within hosts.
Metabolic reprogramming by histone deacetylase inhibition preferentially targets NRF2-activated tumors.
Pyrimidine salvage in Toxoplasma gondii as a target for new treatment.
Deacetylation of Histones and Non-histone Proteins in Inflammatory Diseases and Cancer Therapeutic Potential of Histone Deacetylase Inhibitors.
Specific regulation of epigenome landscape by metabolic enzymes and metabolites.
Plasmodium falciparum ZIP1 Is a Zinc-Selective Transporter with Stage-Dependent Targeting to the Apicoplast and Plasma Membrane in Erythrocytic Parasites.
An autophagy-independent role of ULK1/ULK2 in mechanotransduction and breast cancer cell migration.

Mol Biol Cell. 2024 Jan 03. mbcE23110418

The initiation and early development of the tubulin-containing cytoskeleton in the human parasite Toxoplasma gondii.

Luisa F Arias Padilla, John M Murray, Ke Hu.

The tubulin-containing cytoskeleton of the human parasite Toxoplasma gondii includes several distinct structures: the conoid, formed of 14 ribbon-like tubulin polymers, and the array of 22 cortical microtubules (MTs) rooted in the apical polar ring. Here we analyze the structure of developing daughter parasites using both 3D-SIM and expansion microscopy. Cortical MTs and the conoid start to develop almost simultaneously, but from distinct precursors near the centrioles. Cortical MTs are initiated in a fixed sequence, starting around the periphery of a short arc that extends to become a complete circle. The conoid also develops from an open arc into a full circle, with a fixed spatial relationship to the centrioles. The patterning of the MT array starts from a "blueprint" with ∼ 5-fold symmetry, switching to 22-fold rotational symmetry in the final product, revealing a major structural rearrangement during daughter growth. The number of MT is essentially invariant in the wild-type array, but is perturbed by the loss of some structural components of the apical polar ring. This study provides insights into the development of tubulin-containing structures that diverge from conventional models, insights that are critical for understanding the evolutionary paths leading to construction and divergence of cytoskeletal frameworks.

DOI: https://doi.org/10.1091/mbc.E23-11-0418
Curr Res Microb Sci. 2023 ;5 100197

Editorial overview: Modern approaches to dissect host-pathogen interactions.

Marcio C Silva-Filho, Celia R S Garcia.



Keywords:  Drug-resistant bacteria; IP3 receptor; MDR1; Plasmodium falciparum; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.crmicr.2023.100197
Acta Trop. 2023 Dec 27. pii: S0001-706X(23)00299-1. [Epub ahead of print]251 107112

Toxoplasma gondii surface antigen 1 (SAG1) interacts in vitro with host cell receptor for activated C kinase 1 (RACK1).

Dawei Wang, Yuming Liu, Baoling Yang, Zixuan Zhang, Saeed El-Ashram, Xiaogang Liu, Bing Li.

  Toxoplasma gondii (T. gondii) surface antigen 1 (SAG1) is crucial for tachyzoite invasion into host cells. However, the role of SAG1 in interaction with host cells remains unknown. The primary objective of this study was to analyze and validate the interaction between SAG1 and host cells. RACK1, an intracellular multifunctional protein, was identified as a SAG1 binding partner in host cells. Furthermore, the expression of RACK1 is manipulated by SAG1, and depletion of RACK1 negatively regulated host cell viability. These results imply that through interaction with RACK1, SAG1 preserves the viability of host cells to satisfy the survival needs of T. gondii. Our findings suggest a novel role for SAG1 in intracellular parasitism.

Keywords:  Cell viability; Interaction; RACK1; SAG1; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.actatropica.2023.107112
Cell Rep. 2023 Dec 28. pii: S2211-1247(23)01613-3. [Epub ahead of print]43(1): 113601

Toxoplasma membrane inositol phospholipid binding protein TgREMIND is essential for secretory organelle function and host infection.

Rodrigue Houngue, Lamba Omar Sangaré, Tchilabalo Dilezitoko Alayi, Aissatou Dieng, Tristan Bitard-Feildel, Claire Boulogne, Christian Slomianny, Cynthia Menonve Atindehou, Lucie Ayi Fanou, Yetrib Hathout, Isabelle Callebaut, Stanislas Tomavo.

  Apicomplexan parasites possess specialized secretory organelles called rhoptries, micronemes, and dense granules that play a vital role in host infection. In this study, we demonstrate that TgREMIND, a protein found in Toxoplasma gondii, is necessary for the biogenesis of rhoptries and dense granules. TgREMIND contains a Fes-CIP4 homology-Bin/Amphiphysin/Rvs (F-BAR) domain, which binds to membrane phospholipids, as well as a novel uncharacterized domain that we have named REMIND (regulator of membrane-interacting domain). Both the F-BAR domain and the REMIND are crucial for TgREMIND functions. When TgREMIND is depleted, there is a significant decrease in the abundance of dense granules and abnormal transparency of rhoptries, leading to a reduction in protein secretion from these organelles. The absence of TgREMIND inhibits host invasion and parasite dissemination, demonstrating that TgREMIND is essential for the proper function of critical secretory organelles required for successful infection by Toxoplasma.

Keywords:  CP: Microbiology; F-BAR-containing protein; REMIND domain; TgREMIND protein; Toxoplasma gondii; apicomplexan parasites; host cell infection; lineage-specific organelles; membrane lipid binding

DOI:  https://doi.org/10.1016/j.celrep.2023.113601
Nat Microbiol. 2024 Jan;9(1): 17-28

Toxoplasma protein export and effector function.

Simona Seizova, Abel Ferrel, John Boothroyd, Christopher J Tonkin.

Toxoplasma gondii is a single-celled eukaryotic parasite with a considerable host range that must invade the cells of warm-blooded hosts to survive and replicate. The challenges and opportunities that such a strategy represent have been met by the evolution of effectors that are delivered into host cells, counter host defences and co-opt host cell functions for their own purposes. These effectors are delivered in two waves using distinct machinery for each. In this Review, we focus on understanding the architecture of these protein-export systems and how their protein cargo is recognized and selected. We discuss the recent findings on the role that host manipulation has in latent Toxoplasma infections. We also discuss how these recent findings compare to protein export in the related Plasmodium spp. (the causative agent of malaria) and how this can inform our understanding of host manipulation in the larger Apicomplexa phylum and its evolution.

DOI: https://doi.org/10.1038/s41564-023-01563-z
bioRxiv. 2023 Dec 14. pii: 2023.12.13.571530. [Epub ahead of print]

Host E3 ubiquitin ligase ITCH mediates Toxoplasma gondii effector GRA35-triggered NLRP1 inflammasome activation and cell-autonomous immunity.

Yifan Wang, L Robert Hollingsworth, Lamba Omar Sangaré, Tatiana C Paredes-Santos, Shruthi Krishnamurthy, Bennett H Penn, Hao Wu, Jeroen P J Saeij.

Toxoplasma gondii is an intracellular parasite that can activate the NLRP1 inflammasome leading to macrophage pyroptosis in Lewis rats, but the underlying mechanism is not well understood. In this study, we performed a genome-wide CRISPR screen and identified the dense granule proteins GRA35, GRA42, and GRA43 as the Toxoplasma effectors mediating cell death in Lewis rat macrophages. GRA35 localizes on the parasitophorous vacuole membrane, where it interacts with the host E3 ubiquitin ligase ITCH. Inhibition of proteasome activity or ITCH knockout prevented pyroptosis in Toxoplasma -infected Lewis rat macrophages, consistent with the "NLRP1 functional degradation model". However, there was no evidence that ITCH directly ubiquitinates or interacts with rat NLRP1. We also found that GRA35-ITCH interaction affected Toxoplasma fitness in IFNγ-activated human fibroblasts, likely due to ITCH's role in recruiting ubiquitin and the parasite-restriction factor RNF213 to the parasitophorous vacuole membrane. These findings identify a new role of host E3 ubiquitin ligase ITCH in mediating effector-triggered immunity, a critical concept that involves recognizing intracellular pathogens and initiating host innate immune responses.
IMPORTANCE: Effector-triggered immunity represents an innate immune defense mechanism that plays a crucial role in sensing and controlling intracellular pathogen infection. The NLRP1 inflammasome in the Lewis rats can detect Toxoplasma infection, which triggers proptosis in infected macrophages and eliminates the parasite's replication niche. The work reported here revealed that host E3 ubiquitin ligase ITCH is able to recognize and interact with Toxoplasma effector protein GRA35 localized on the parasite-host interface, leading to NLRP1 inflammasome activation in Lewis rat macrophages. Furthermore, ITCH-GRA35 interaction contributes to the restriction of Toxoplasma in human fibroblasts stimulated by IFNγ. Thus, this research provides valuable insights into understanding pathogen recognition and restriction mediated by host E3 ubiquitin ligase.

DOI: https://doi.org/10.1101/2023.12.13.571530
Trends Parasitol. 2024 Jan 02. pii: S1471-4922(23)00292-1. [Epub ahead of print]

Biomechanics of parasite migration within hosts.

Yi-Ting Yeh, Juan C Del Álamo, Conor R Caffrey.

  The dissemination of protozoan and metazoan parasites through host tissues is hindered by cellular barriers, dense extracellular matrices, and fluid forces in the bloodstream. To overcome these diverse biophysical impediments, parasites implement versatile migratory strategies. Parasite-exerted mechanical forces and upregulation of the host's cellular contractile machinery are the motors for these strategies, and these are comparably better characterized for protozoa than for helminths. Using the examples of the protozoans, Toxoplasma gondii and Plasmodium, and the metazoan, Schistosoma mansoni, we highlight how quantitative tools such as traction force and reflection interference contrast microscopies have improved our understanding of how parasites alter host mechanobiology to promote their migration.

Keywords:  biomechanics; metazoan; parasite migration; protozoan; traction force

DOI:  https://doi.org/10.1016/j.pt.2023.12.001
Cell Rep. 2023 Dec 30. pii: S2211-1247(23)01640-6. [Epub ahead of print]43(1): 113629

Metabolic reprogramming by histone deacetylase inhibition preferentially targets NRF2-activated tumors.

Dimitris Karagiannis, Warren Wu, Albert Li, Makiko Hayashi, Xiao Chen, Michaela Yip, Vaibhav Mangipudy, Xinjing Xu, Francisco J Sánchez-Rivera, Yadira M Soto-Feliciano, Jiangbin Ye, Thales Papagiannakopoulos, Chao Lu.

  The interplay between metabolism and chromatin signaling is implicated in cancer progression. However, whether and how metabolic reprogramming in tumors generates chromatin vulnerabilities remain unclear. Lung adenocarcinoma (LUAD) tumors frequently harbor aberrant activation of the NRF2 antioxidant pathway, which drives aggressive and chemo-resistant disease. Using a chromatin-focused CRISPR screen, we report that NRF2 activation sensitizes LUAD cells to genetic and chemical inhibition of class I histone deacetylases (HDACs). This association is observed across cultured cells, mouse models, and patient-derived xenografts. Integrative epigenomic, transcriptomic, and metabolomic analysis demonstrates that HDAC inhibition causes widespread redistribution of H4ac and its reader protein, which transcriptionally downregulates metabolic enzymes. This results in reduced flux into amino acid metabolism and de novo nucleotide synthesis pathways that are preferentially required for the survival of NRF2-active cancer cells. Together, our findings suggest NRF2 activation as a potential biomarker for effective repurposing of HDAC inhibitors to treat solid tumors.

Keywords:  CP: Cancer; HDAC inhibitors; NRF2 pathway; cancer epigenetics; cancer metabolism; cancer targeted therapy; epigenetic reprogramming; lung cancer

DOI:  https://doi.org/10.1016/j.celrep.2023.113629
Front Cell Infect Microbiol. 2023 ;13 1320160

Pyrimidine salvage in Toxoplasma gondii as a target for new treatment.

Hamza A A Elati, Amber L Goerner, Bruno Martorelli Di Genova, Lilach Sheiner, Harry P de Koning.

  Toxoplasmosis is a common protozoan infection that can have severe outcomes in the immunocompromised and during pregnancy, but treatment options are limited. Recently, nucleotide metabolism has received much attention as a target for new antiprotozoal agents and here we focus on pyrimidine salvage by Toxoplasma gondii as a drug target. Whereas uptake of [3H]-cytidine and particularly [3H]-thymidine was at most marginal, [3H]-uracil and [3H]-uridine were readily taken up. Kinetic analysis of uridine uptake was consistent with a single transporter with a Km of 3.3 ± 0.8 µM, which was inhibited by uracil with high affinity (Ki = 1.15 ± 0.07 µM) but not by thymidine or 5-methyluridine, showing that the 5-Me group is incompatible with uptake by T. gondii. Conversely, [3H]-uracil transport displayed a Km of 2.05 ± 0.40 µM, not significantly different from the uracil Ki on uridine transport, and was inhibited by uridine with a Ki of 2.44 ± 0.59 µM, also not significantly different from the experimental uridine Km. The reciprocal, complete inhibition, displaying Hill slopes of approximately -1, strongly suggest that uridine and uracil share a single transporter with similarly high affinity for both, and we designate it uridine/uracil transporter 1 (TgUUT1). While TgUUT1 excludes 5-methyl substitutions, the smaller 5F substitution was tolerated, as 5F-uracil inhibited uptake of [3H]-uracil with a Ki of 6.80 ± 2.12 µM (P > 0.05 compared to uracil Km). Indeed, we found that 5F-Uridine, 5F-uracil and 5F,2'-deoxyuridine were all potent antimetabolites against T. gondii with EC50 values well below that of the current first line treatment, sulfadiazine. In vivo evaluation also showed that 5F-uracil and 5F,2'-deoxyuridine were similarly effective as sulfadiazine against acute toxoplasmosis. Our preliminary conclusion is that TgUUT1 mediates potential new anti-toxoplasmosis drugs with activity superior to the current treatment.

Keywords:  5-fluorodeoxyuridine; 5-fluorouracil; Toxoplasma gondi; antimetabolite; fluoropyrimidines; pyrimidine salvage; uracil transporter; uridine transport

DOI:  https://doi.org/10.3389/fcimb.2023.1320160
Curr Genomics. 2023 Nov 22. 24(3): 136-145

Deacetylation of Histones and Non-histone Proteins in Inflammatory Diseases and Cancer Therapeutic Potential of Histone Deacetylase Inhibitors.

Ezgi Man, Serap Evran.

  Epigenetic changes play an important role in the pathophysiology of autoimmune diseases such as allergic asthma, multiple sclerosis, lung diseases, diabetes, cystic fibrosis, atherosclerosis, rheumatoid arthritis, and COVID-19. There are three main classes of epigenetic alterations: post-translational modifications of histone proteins, control by non-coding RNA and DNA methylation. Since histone modifications can directly affect chromatin structure and accessibility, they can regulate gene expression levels. Abnormal expression and activity of histone deacetylases (HDACs) have been reported in immune mediated diseases. Increased acetylated levels of lysine residues have been suggested to be related to the overexpression of inflammatory genes. This review focuses on the effect of HDAC modifications on histone and non-histone proteins in autoimmune diseases. Furthermore, we discuss the potential therapeutic effect of HDAC inhibitors (HDACi) used in these diseases.

Keywords:  Autoimmune diseases; HDAC inhibitors; HDACs; epigenetics; histone deacetylase; histone protein modifications; lysine deacetylation; non-histone protein modifications

DOI:  https://doi.org/10.2174/0113892029265046231011100327
Biol Rev Camb Philos Soc. 2024 Jan 04.

Specific regulation of epigenome landscape by metabolic enzymes and metabolites.

Xilan Yu, Shanshan Li.

  Metabolism includes anabolism and catabolism, which play an essential role in many biological processes. Chromatin modifications are post-translational modifications of histones and nucleic acids that play important roles in regulating chromatin-associated processes such as gene transcription. There is a tight connection between metabolism and chromatin modifications. Many metabolic enzymes and metabolites coordinate cellular activities with alterations in nutrient availability by regulating gene expression through epigenetic mechanisms such as DNA methylation and histone modifications. The dysregulation of gene expression by metabolism and epigenetic modifications may lead to diseases such as diabetes and cancer. Recent studies reveal that metabolic enzymes and metabolites specifically regulate chromatin modifications, including modification types, modification residues and chromatin regions. This specific regulation has been implicated in the development of human diseases, yet the underlying mechanisms are only beginning to be uncovered. In this review, we summarise recent studies of the molecular mechanisms underlying the metabolic regulation of histone and DNA modifications and discuss how they contribute to pathogenesis. We also describe recent developments in technologies used to address the key questions in this field. We hope this will inspire further in-depth investigations of the specific regulatory mechanisms involved, and most importantly will shed lights on the development of more effective disease therapies.

Keywords:  DNA methylation; cell fate determination; chromatin structure; epigenetic modifications; gene transcription; histone modifications; metabolism; oncogenesis

DOI:  https://doi.org/10.1111/brv.13049
ACS Infect Dis. 2024 Jan 01.

Plasmodium falciparum ZIP1 Is a Zinc-Selective Transporter with Stage-Dependent Targeting to the Apicoplast and Plasma Membrane in Erythrocytic Parasites.

Deepti Shrivastava, Akanksha Jha, Rajlakshmi Kabrambam, Jyoti Vishwakarma, Kalyan Mitra, Ravishankar Ramachandran, Saman Habib.

  Replication of the malarial parasite in human erythrocytes requires massive zinc fluxes, necessitating the action of zinc transporters across the parasite plasma and organellar membranes. Although genetic knockout studies have been conducted on a few "orphan" zinc transporters in Plasmodium spp., none of them have been functionally characterized. We used the recombinant Plasmodium falciparum Zrt-/Irt-like protein (PfZIP1) and specific antibodies generated against it to explore the subcellular localization, function, metal-ion selectivity, and response to cellular zinc levels. PfZIP1 expression was enhanced upon the depletion of cytosolic Zn2+. The protein transitioned from the processed to unprocessed form through blood stages, localizing to the apicoplast in trophozoites and to the parasite plasma membrane in schizonts and gametocytes, indicating stage-specific functional role. The PfZIP1 dimer mediated Zn2+ influx in proteoliposomes. It exhibited preferential binding to Zn2+ compared to Fe2+, with the selectivity for zinc being driven by a C-terminal histidine-rich region conserved only in primate-infecting Plasmodium species.

Keywords:  Plasmodium falciparum; ZIP1; apicoplast; histidine-rich loop; zinc transport

DOI:  https://doi.org/10.1021/acsinfecdis.3c00426
Autophagy. 2024 Jan 01. 1-2

An autophagy-independent role of ULK1/ULK2 in mechanotransduction and breast cancer cell migration.

Peigang Liang, Bo Wang.

  The progression of breast cancer is often accompanied by changes in extracellular matrix stiffness and cell adhesion ability, which are closely related to cellular mechanotransduction. However, the underlying regulatory mechanisms remain mysterious. Our study reveals that the macroautophagy/autophagy-inducing kinases, ULK1 and ULK2, inhibit the assembly of focal adhesions and F-actin by phosphorylating the adhesion protein PXN, to prevent breast cancer cell migration in an autophagy-independent fashion. Interestingly, ULK1/ULK2-mediated serine phosphorylation of PXN counteracts PXN phosphorylation at the adjacent tyrosine residues by PTK2 and SRC, to gatekeep cellular mechanotransduction. Our research establishes a new function of ULK1/ULK2 in governing cellular mechanotransduction that might be harnessed for treating breast cancer.

Keywords:  Breast cancer; PXN; ULK1/2; cell migration; focal adhesions; mechanotransduction

DOI:  https://doi.org/10.1080/15548627.2023.2300916