scholarly journals m6A RNA methylation facilitates pre-mRNA 3’-end formation and is essential for viability of Toxoplasma gondii

2021 ◽  
Vol 17 (7) ◽  
pp. e1009335
Author(s):  
Michael J. Holmes ◽  
Leah R. Padgett ◽  
Matheus S. Bastos ◽  
William J. Sullivan
Keyword(s):  
Gene Regulation ◽  
Toxoplasma Gondii ◽  
Congenital Infection ◽  
Epigenetic Factors ◽  
Obligate Intracellular ◽  
Opportunistic Disease ◽  
Cleavage And Polyadenylation ◽  
Parasite Replication ◽  
Parasite Viability ◽  
M6a Rna Methylation

Toxoplasma gondii is an obligate intracellular parasite that can cause serious opportunistic disease in the immunocompromised or through congenital infection. To progress through its life cycle, Toxoplasma relies on multiple layers of gene regulation that includes an array of transcription and epigenetic factors. Over the last decade, the modification of mRNA has emerged as another important layer of gene regulation called epitranscriptomics. Here, we report that epitranscriptomics machinery exists in Toxoplasma, namely the methylation of adenosines (m6A) in mRNA transcripts. We identified novel components of the m6A methyltransferase complex and determined the distribution of m6A marks within the parasite transcriptome. m6A mapping revealed the modification to be preferentially located near the 3’-boundary of mRNAs. Knockdown of the m6A writer components METTL3 and WTAP resulted in diminished m6A marks and a complete arrest of parasite replication. Furthermore, we examined the two proteins in Toxoplasma that possess YTH domains, which bind m6A marks, and showed them to be integral members of the cleavage and polyadenylation machinery that catalyzes the 3’-end processing of pre-mRNAs. Loss of METTL3, WTAP, or YTH1 led to a defect in transcript 3’-end formation. Together, these findings establish that the m6A epitranscriptome is essential for parasite viability by contributing to the processing of mRNA 3’-ends.

scholarly journals m6A RNA methylation facilitates pre-mRNA 3’-end formation and is essential for viability of Toxoplasma gondii

2021 ◽  
Author(s):  
Michael J. Holmes ◽  
Leah R. Padgett ◽  
Matheus S. Bastos ◽  
William J. Sullivan
Keyword(s):  
Gene Regulation ◽  
Life Cycle ◽  
Toxoplasma Gondii ◽  
Consensus Sequence ◽  
Congenital Infection ◽  
Messenger Rnas ◽  
Parasite Life Cycle ◽  
Opportunistic Disease ◽  
Mrna Maturation ◽  
Parasite Replication

AbstractToxoplasma gondii is an obligate intracellular parasite that can cause serious opportunistic disease in the immunocompromised or through congenital infection. To progress through its life cycle, Toxoplasma relies on multiple layers of gene regulation that includes an array of transcription and epigenetic factors. Over the last decade, the modification of mRNA has emerged as another important layer of gene regulation called epitranscriptomics. Here, we report that epitranscriptomics machinery exists in Toxoplasma, namely the methylation of adenosines (m6A) in mRNA transcripts. We identified novel components of the m6A methyltransferase complex and determined the distribution of m6A marks within the parasite transcriptome. m6A mapping revealed the modification to be preferentially located near the 3’-boundary of mRNAs within the consensus sequence, YGCAUGCR. Knockdown of the m6A writer enzyme METTL3 resulted in diminished m6A marks, loss of a target transcript, and a complete arrest of parasite replication. Furthermore, we examined the two proteins in Toxoplasma that possess YTH domains, which bind m6A marks, and showed them to be integral members of the cleavage and polyadenylation machinery that catalyzes the 3’-end processing of pre-mRNAs. Together, these findings establish that the m6A epitranscriptome is essential for parasite viability by contributing to the processing of mRNA 3’-ends.Author SummaryToxoplasma gondii is a parasite of medical importance that causes disease upon immuno-suppression. Uncovering essential pathways that the parasite uses for its basic biological processes may reveal opportunities for new anti-parasitic drug therapies. Here, we describe the machinery that Toxoplasma uses to modify specific adenosine residues within its messenger RNAs (mRNA) by N6-adenosine methylation (m6A). We discovered that m6A mRNA methylation is prevalent in multiple stages of the parasite life cycle and is required for parasite replication. We also establish that m6A plays a major role in the proper maturation of mRNA. Two proteins that bind m6A modifications on mRNA associate with factors responsible for the cleavage and final processing steps of mRNA maturation. Since all of the machinery is conserved from plants to Toxoplasma and other related parasites, we propose that this system operates similarly in these organisms.

scholarly journals Prevalence of Toxoplasmosis antibodies in blood donors in Tripoli area

2021 ◽  
Vol 10 (2) ◽  
pp. 169-175
Author(s):  
Khaled A. Alawaini ◽  
Safia O. Albhlool ◽  
Entesar O. Shaife ◽  
Hanein A. Qreiwa ◽  
Manal K. Abodena
Keyword(s):  
Toxoplasma Gondii ◽  
Blood Transfusion ◽  
High Performance ◽  
Blood Donors ◽  
Congenital Infection ◽  
Capital City ◽  
Obligate Intracellular ◽  
Performance Techniques ◽  
Immunocompromised Individual ◽  
Blood Screening

Toxoplasma gondii is the organism that is responsible for toxoplasmosis disease. Toxoplasma gondii: is a crucial obligate intracellular parasite of humans and animals worldwide and infects nearly one-third of humanity; the disease can be severe and can lead to abortion or neonate’s death. In addition, an immunocompromised individual may develop several syndromes such as encephalitis, chorioretinitis, congenital infection and neonatal mortality. In this study, our objective is to determine the prevalence of Toxoplasma gondii antibodies through blood transfusion. Therefore, our study was conducted from 1 May 2010 to 31 of May 2010 among Libyan donors. We tested 164 blood donors from different ages for Toxoplasma gondii antibodies in Tripoli, a capital city of Libya. The results showed that 33.5% of blood donors had positive IgG antibodies. Therefore, this study suggest blood screening with high-performance techniques for Toxoplasma gondii before blood transfusion should be routinely done to avoid severe complications.

scholarly journals Toxoplasma gondiisalvages sphingolipids from the host Golgi through the rerouting of selected Rab vesicles to the parasitophorous vacuole

2013 ◽  
Vol 24 (12) ◽  
pp. 1974-1995 ◽  
Author(s):  
Julia D. Romano ◽  
Sabrina Sonda ◽  
Emily Bergbower ◽  
Maria Elisa Smith ◽  
Isabelle Coppens
Keyword(s):  
Toxoplasma Gondii ◽  
Mammalian Cells ◽  
De Novo ◽  
Parasitophorous Vacuole ◽  
Parasite Growth ◽  
Sphingolipid Metabolism ◽  
Obligate Intracellular ◽  
Membrane Bound ◽  
Parasite Replication

The obligate intracellular protozoan Toxoplasma gondii actively invades mammalian cells and, upon entry, forms its own membrane-bound compartment, named the parasitophorous vacuole (PV). Within the PV, the parasite replicates and scavenges nutrients, including lipids, from host organelles. Although T. gondii can synthesize sphingolipids de novo, it also scavenges these lipids from the host Golgi. How the parasite obtains sphingolipids from the Golgi remains unclear, as the PV avoids fusion with host organelles. In this study, we explore the host Golgi–PV interaction and evaluate the importance of host-derived sphingolipids for parasite growth. We demonstrate that the PV preferentially localizes near the host Golgi early during infection and remains closely associated with this organelle throughout infection. The parasite subverts the structure of the host Golgi, resulting in its fragmentation into numerous ministacks, which surround the PV, and hijacks host Golgi–derived vesicles within the PV. These vesicles, marked with Rab14, Rab30, or Rab43, colocalize with host-derived sphingolipids in the vacuolar space. Scavenged sphingolipids contribute to parasite replication since alterations in host sphingolipid metabolism are detrimental for the parasite's growth. Thus our results reveal that T. gondii relies on host-derived sphingolipids for its development and scavenges these lipids via Golgi-derived vesicles.

scholarly journals Recent Advances in the Roles of Autophagy and Autophagy Proteins in Host Cells During Toxoplasma gondii Infection and Potential Therapeutic Implications

2021 ◽  
Vol 9 ◽  
Author(s):  
Carlos S. Subauste
Keyword(s):  
Toxoplasma Gondii ◽  
Parasitophorous Vacuole ◽  
Host Cells ◽  
Lysosomal Degradation ◽  
Therapeutic Implications ◽  
Obligate Intracellular ◽  
Recent Advances ◽  
Parasite Replication ◽  
Toxoplasma Gondii Infection ◽  
The Brain

Toxoplasma gondii is an obligate intracellular protozoan that can cause encephalitis and retinitis in humans. The success of T. gondii as a pathogen depends in part on its ability to form an intracellular niche (parasitophorous vacuole) that allows protection from lysosomal degradation and parasite replication. The parasitophorous vacuole can be targeted by autophagy or by autophagosome-independent processes triggered by autophagy proteins. However, T. gondii has developed many strategies to preserve the integrity of the parasitophorous vacuole. Here, we review the interaction between T. gondii, autophagy, and autophagy proteins and expand on recent advances in the field, including the importance of autophagy in the regulation of invasion of the brain and retina by the parasite. We discuss studies that have begun to explore the potential therapeutic applications of the knowledge gained thus far.

scholarly journals Secreted Effectors Modulating Immune Responses to Toxoplasma gondii

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 988
Author(s):  
Tadakimi Tomita ◽  
Rebekah B. Guevara ◽  
Lamisha M. Shah ◽  
Andrews Y. Afrifa ◽  
Louis M. Weiss
Keyword(s):  
Toxoplasma Gondii ◽  
Immune Responses ◽  
Inflammatory Responses ◽  
Parasitophorous Vacuole ◽  
Congenital Infection ◽  
Dense Granule ◽  
Obligate Intracellular ◽  
Host Cytoplasm ◽  
Life Threatening ◽  
Intracellular Milieu

Toxoplasma gondii is an obligate intracellular parasite that chronically infects a third of humans. It can cause life-threatening encephalitis in immune-compromised individuals. Congenital infection also results in blindness and intellectual disabilities. In the intracellular milieu, parasites encounter various immunological effectors that have been shaped to limit parasite infection. Parasites not only have to suppress these anti-parasitic inflammatory responses but also ensure the host organism’s survival until their subsequent transmission. Recent advancements in T. gondii research have revealed a plethora of parasite-secreted proteins that suppress as well as activate immune responses. This mini-review will comprehensively examine each secreted immunomodulatory effector based on the location of their actions. The first section is focused on secreted effectors that localize to the parasitophorous vacuole membrane, the interface between the parasites and the host cytoplasm. Murine hosts are equipped with potent IFNγ-induced immune-related GTPases, and various parasite effectors subvert these to prevent parasite elimination. The second section examines several cytoplasmic and ER effectors, including a recently described function for matrix antigen 1 (MAG1) as a secreted effector. The third section covers the repertoire of nuclear effectors that hijack transcription factors and epigenetic repressors that alter gene expression. The last section focuses on the translocation of dense-granule effectors and effectors in the setting of T. gondii tissue cysts (the bradyzoite parasitophorous vacuole).

scholarly journals Untargeted Metabolomics Uncovers the Essential Lysine Transporter in Toxoplasma gondii

Metabolites ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 476
Author(s):  
Joachim Kloehn ◽  
Matteo Lunghi ◽  
Emmanuel Varesio ◽  
David Dubois ◽  
Dominique Soldati-Favre
Keyword(s):  
Amino Acids ◽  
Toxoplasma Gondii ◽  
Rna Degradation ◽  
Major Facilitator Superfamily ◽  
Untargeted Metabolomics ◽  
Apicomplexan Parasites ◽  
Obligate Intracellular ◽  
Intracellular Parasites ◽  
Major Facilitator ◽  
Plasma Membrane Transporter

Apicomplexan parasites are responsible for devastating diseases, including malaria, toxoplasmosis, and cryptosporidiosis. Current treatments are limited by emerging resistance to, as well as the high cost and toxicity of existing drugs. As obligate intracellular parasites, apicomplexans rely on the uptake of many essential metabolites from their host. Toxoplasma gondii, the causative agent of toxoplasmosis, is auxotrophic for several metabolites, including sugars (e.g., myo-inositol), amino acids (e.g., tyrosine), lipidic compounds and lipid precursors (cholesterol, choline), vitamins, cofactors (thiamine) and others. To date, only few apicomplexan metabolite transporters have been characterized and assigned a substrate. Here, we set out to investigate whether untargeted metabolomics can be used to identify the substrate of an uncharacterized transporter. Based on existing genome- and proteome-wide datasets, we have identified an essential plasma membrane transporter of the major facilitator superfamily in T. gondii—previously termed TgApiAT6-1. Using an inducible system based on RNA degradation, TgApiAT6-1 was depleted, and the mutant parasite’s metabolome was compared to that of non-depleted parasites. The most significantly reduced metabolite in parasites depleted in TgApiAT6-1 was identified as the amino acid lysine, for which T. gondii is predicted to be auxotrophic. Using stable isotope-labeled amino acids, we confirmed that TgApiAT6-1 is required for efficient lysine uptake. Our findings highlight untargeted metabolomics as a powerful tool to identify the substrate of orphan transporters.

scholarly journals Loss of the Conserved Alveolate Kinase MAPK2 Decouples Toxoplasma Cell Growth from Cell Division

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Xiaoyu Hu ◽  
William J. O’Shaughnessy ◽  
Tsebaot G. Beraki ◽  
Michael L. Reese
Keyword(s):  
Toxoplasma Gondii ◽  
Protein Kinases ◽  
Daughter Cell ◽  
Protozoan Parasite ◽  
Productive Infection ◽  
Centrosome Duplication ◽  
Loss Of Function ◽  
Content Type ◽  
Mitogen Activated Protein ◽  
Parasite Replication

ABSTRACT Mitogen-activated protein kinases (MAPKs) are a conserved family of protein kinases that regulate signal transduction, proliferation, and development throughout eukaryotes. The apicomplexan parasite Toxoplasma gondii expresses three MAPKs. Two of these, extracellular signal-regulated kinase 7 (ERK7) and MAPKL1, have been implicated in the regulation of conoid biogenesis and centrosome duplication, respectively. The third kinase, MAPK2, is specific to and conserved throughout the Alveolata, although its function is unknown. We used the auxin-inducible degron system to determine phenotypes associated with MAPK2 loss of function in Toxoplasma. We observed that parasites lacking MAPK2 failed to duplicate their centrosomes and therefore did not initiate daughter cell budding, which ultimately led to parasite death. MAPK2-deficient parasites initiated but did not complete DNA replication and arrested prior to mitosis. Surprisingly, the parasites continued to grow and replicate their Golgi apparatus, mitochondria, and apicoplasts. We found that the failure in centrosome duplication is distinct from the phenotype caused by the depletion of MAPKL1. As we did not observe MAPK2 localization at the centrosome at any point in the cell cycle, our data suggest that MAPK2 regulates a process at a distal site that is required for the completion of centrosome duplication and the initiation of parasite mitosis. IMPORTANCE Toxoplasma gondii is a ubiquitous intracellular protozoan parasite that can cause severe and fatal disease in immunocompromised patients and the developing fetus. Rapid parasite replication is critical for establishing a productive infection. Here, we demonstrate that a Toxoplasma protein kinase called MAPK2 is conserved throughout the Alveolata and essential for parasite replication. We found that parasites lacking MAPK2 protein were defective in the initiation of daughter cell budding and were rendered inviable. Specifically, T. gondii MAPK2 (TgMAPK2) appears to be required for centrosome replication at the basal end of the nucleus, and its loss causes arrest early in parasite division. MAPK2 is unique to the Alveolata and not found in metazoa and likely is a critical component of an essential parasite-specific signaling network.

scholarly journals Novel Gene Regulation in Normal and Abnormal Spermatogenesis

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 666
Author(s):  
Li Du ◽  
Wei Chen ◽  
Zixin Cheng ◽  
Si Wu ◽  
Jian He ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Leydig Cells ◽  
Molecular Mechanisms ◽  
New Technologies ◽  
Genetic Regulation ◽  
Myoid Cells ◽  
Epigenetic Factors ◽  
Future Directions ◽  
New Genes ◽  
Human Spermatogenesis

Spermatogenesis is a complex and dynamic process which is precisely controlledby genetic and epigenetic factors. With the development of new technologies (e.g., single-cell RNA sequencing), increasingly more regulatory genes related to spermatogenesis have been identified. In this review, we address the roles and mechanisms of novel genes in regulating the normal and abnormal spermatogenesis. Specifically, we discussed the functions and signaling pathways of key new genes in mediating the proliferation, differentiation, and apoptosis of rodent and human spermatogonial stem cells (SSCs), as well as in controlling the meiosis of spermatocytes and other germ cells. Additionally, we summarized the gene regulation in the abnormal testicular microenvironment or the niche by Sertoli cells, peritubular myoid cells, and Leydig cells. Finally, we pointed out the future directions for investigating the molecular mechanisms underlying human spermatogenesis. This review could offer novel insights into genetic regulation in the normal and abnormal spermatogenesis, and it provides new molecular targets for gene therapy of male infertility.

Microtubules, but not actin filaments, drive daughter cell budding and cell division in Toxoplasma gondii

2000 ◽  
Vol 113 (7) ◽  
pp. 1241-1254 ◽  
Author(s):  
M.K. Shaw ◽  
H.L. Compton ◽  
D.S. Roos ◽  
L.G. Tilney
Keyword(s):  
Toxoplasma Gondii ◽  
Actin Cytoskeleton ◽  
Daughter Cell ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Actin Dynamics ◽  
Residual Body ◽  
Cell Organelles ◽  
Infection Period ◽  
Parasite Replication

We have used drugs to examine the role(s) of the actin and microtubule cytoskeletons in the intracellular growth and replication of the intracellular protozoan parasite, Toxoplasma gondii. By using a 5 minute infection period and adding the drugs shortly after entry we can treat parasites at the start of intracellular development and 6–8 hours prior to the onset of daughter cell budding. Using this approach we found, somewhat surprisingly, that reagents that perturb the actin cytoskeleton in different ways (cytochalasin D, latrunculin A and jasplakinolide) had little effect on parasite replication although they had the expected effects on the host cells. These actin inhibitors did, however, disrupt the orderly turnover of the mother cell organelles leading to the formation of a large residual body at the posterior end of each pair of budding parasites. Treating established parasite cultures with the actin inhibitors blocked ionophore-induced egression of tachyzoites from the host cells, demonstrating that intracellular parasites were susceptible to the effects of these inhibitors. In contrast, the anti-microtubule drugs oryzalin and taxol, and to a much lesser extent nocodazole, which affect microtubule dynamics in different ways, blocked parasite replication by disrupting the normal assembly of the apical conoid and the microtubule inner membrane complex (IMC) in the budding daughter parasites. Centrosome replication and assembly of intranuclear spindles, however, occurred normally. Thus, daughter cell budding per se is dependent primarily on the parasite microtubule system and does not require a dynamic actin cytoskeleton, although disruption of actin dynamics causes problems in the turnover of parasite organelles.

scholarly journals Report of an unsual case of anophthalmia and craniofacial cleft in a newborn with Toxoplasma gondii congenital infection

2017 ◽  
Vol 17 (1) ◽  
Author(s):  
Gabriel Emmanuel Arce-Estrada ◽  
Valeria Gómez-Toscano ◽  
Carlos Cedillo-Peláez ◽  
Ana Luisa Sesman-Bernal ◽  
Vanessa Bosch-Canto ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Congenital Infection
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