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Molecular Biology of the Cell Apr 2024Intracellular cargo transport is a ubiquitous cellular process in all eukaryotes. In many cell types, membrane bound cargo is associated with molecular motors which...
Intracellular cargo transport is a ubiquitous cellular process in all eukaryotes. In many cell types, membrane bound cargo is associated with molecular motors which transport cargo along microtubule and actin tracks. In (), an obligate intracellular parasite in the phylum Apicomplexa, organization of the endomembrane pathway depends on actin and an unconventional myosin motor, myosin F (MyoF). Loss of MyoF and actin disrupts vesicle transport, organelle positioning, and division of the apicoplast, a nonphotosynthetic plastid organelle. How this actomyosin system contributes to these cellular functions is still unclear. Using live-cell imaging, we observed that MyoF-EmeraldFP (MyoF-EmFP) displayed a dynamic and filamentous-like organization in the parasite cytosol, reminiscent of cytosolic actin filament dynamics. MyoF was not associated with the Golgi, apicoplast or dense granule surfaces, suggesting that it does not function using the canonical cargo transport mechanism. Instead, we found that loss of MyoF resulted in a dramatic rearrangement of the actin cytoskeleton in interphase parasites accompanied by significantly reduced actin dynamics. However, actin organization during parasite replication and motility was unaffected by the loss of MyoF. These findings revealed that MyoF is an actin organizing protein in and facilitates cargo movement using an unconventional transport mechanism.
Topics: Animals; Actins; Toxoplasma; Myosins; Cytoskeleton; Actin Cytoskeleton; Parasites
PubMed: 38416592
DOI: 10.1091/mbc.E23-12-0510 -
BioRxiv : the Preprint Server For... Jan 2024Morphological modifications and shifts in organelle relationships are hallmarks of dormancy in eukaryotic cells. Communications between altered mitochondria and nuclei...
Morphological modifications and shifts in organelle relationships are hallmarks of dormancy in eukaryotic cells. Communications between altered mitochondria and nuclei are associated with metabolic quiescence of cancer cells that can survive chemotherapy. In plants, changes in the pathways between nuclei, mitochondria, and chloroplasts are associated with cold stress and bud dormancy. parasites, the deadliest agent of malaria in humans, contain a chloroplast-like organelle (apicoplast) derived from an ancient photosynthetic symbiont. Antimalarial treatments can fail because a small fraction of the blood stage parasites enter dormancy and recrudesce after drug exposure. Altered mitochondrial-nuclear interactions in these persisters have been described for , but interactions of the apicoplast remained to be characterized. In the present study, we examined the apicoplasts of dormant persisters obtained after exposure to dihydroartemisinin (a first-line antimalarial drug) followed by sorbitol treatment, or after exposure to sorbitol treatment alone. As previously observed, the mitochondrion of persisters was consistently enlarged and in close association with the nucleus. In contrast, the apicoplast varied from compact and oblate, like those of active ring stage parasites, to enlarged and irregularly shaped. Enlarged apicoplasts became more prevalent later in dormancy, but regular size apicoplasts subsequently predominated when actively replicating parasites recrudesced. All three organelles, nucleus, mitochondrion, and apicoplast, became closer during dormancy. Understanding their relationships in erythrocytic-stage persisters may lead to new strategies to prevent recrudescences and protect the future of malaria chemotherapy.
PubMed: 38410435
DOI: 10.1101/2024.01.03.574077 -
Veterinary Sciences Feb 2024Apicomplexan and nematodes are food-borne parasites whose life cycle is carried-out in various wildlife and domestic animals. The gray wolf () is an apex predator...
Apicomplexan and nematodes are food-borne parasites whose life cycle is carried-out in various wildlife and domestic animals. The gray wolf () is an apex predator acting as an ecosystem engineer. This study aimed to identify the species of and found in the muscles of gray wolves in Lithuania. During the 2017-2022 period, diaphragm, heart, and hind leg samples of 15 animals were examined. Microscopical analysis showed the presence of two types of parasites in 26.7% of the analyzed muscle samples. Based on the sequencing of five loci, nuclear rDNA, rDNA, , mitochondrial , and apicoplast , , and were identified. The current work presents the first report of in gray wolf. Phylogenetically, clustered together with , infecting various carnivorans, and was most closely related to from domestic cats. spp. were found in 12 gray wolves (80%). For the first time, species were molecularly identified in gray wolves from Lithuania. was confirmed in all of the isolated larvae using a multiplex PCR. Gray wolves in Lithuania may serve as a major source of zoonotic pathogens due to the presence of these parasites.
PubMed: 38393103
DOI: 10.3390/vetsci11020085 -
International Journal of Antimicrobial... May 2024The control and elimination of malaria caused by Plasmodium vivax is hampered by the threat of relapsed infection resulting from the activation of dormant hepatic...
The control and elimination of malaria caused by Plasmodium vivax is hampered by the threat of relapsed infection resulting from the activation of dormant hepatic hypnozoites. Currently, only the 8-aminoquinolines, primaquine and tafenoquine, have been approved for the elimination of hypnozoites, although their use is hampered by potential toxicity. Therefore, an alternative radical curative drug that safely eliminates hypnozoites is a pressing need. This study assessed the potential hypnozoiticidal activity of the antibiotic azithromycin, which is thought to exert antimalarial activity by inhibiting prokaryote-like ribosomal translation within the apicoplast, an indispensable organelle. The results show that azithromycin inhibited apicoplast development during liver-stage schizogony in P. vivax and Plasmodium cynomolgi, leading to impaired parasite maturation. More importantly, this study found that azithromycin is likely to impair the hypnozoite's apicoplast, resulting in the loss of this organelle. Subsequently, using a recently developed long-term hepatocyte culture system, this study found that this loss likely induces a delay in the hypnozoite activation rate, and that those parasites that do proceed to schizogony display liver-stage arrest prior to differentiating into hepatic merozoites, thus potentially preventing relapse. Overall, this work provides evidence for the potential use of azithromycin for the radical cure of relapsing malaria, and identifies apicoplast functions as potential drug targets in quiescent hypnozoites.
Topics: Azithromycin; Plasmodium vivax; Plasmodium cynomolgi; Antimalarials; Liver; Apicoplasts; Animals; Hepatocytes; Humans; Organelle Biogenesis; Malaria, Vivax; Mice; Malaria
PubMed: 38367843
DOI: 10.1016/j.ijantimicag.2024.107112 -
BioRxiv : the Preprint Server For... May 2024The malaria causing parasite, , replicates through a tightly orchestrated process termed schizogony, where approximately 32 daughter parasites are formed in a single...
The malaria causing parasite, , replicates through a tightly orchestrated process termed schizogony, where approximately 32 daughter parasites are formed in a single infected red blood cell and thousands of daughter cells in mosquito or liver stages. One-per-cell organelles, such as the mitochondrion and apicoplast, need to be properly divided and segregated to ensure a complete set of organelles per daughter parasites. Although this is highly essential, details about the processes and mechanisms involved remain unknown. We developed a new reporter parasite line that allows visualization of the mitochondrion in blood and mosquito stages. Using high-resolution 3D-imaging, we found that the mitochondrion orients in a cartwheel structure, prior to stepwise, non-geometric division during the last stage of schizogony. Analysis of focused ion beam scanning electron microscopy (FIB-SEM) data confirmed these mitochondrial division stages. Furthermore, these data allowed us to elucidate apicoplast division steps, highlighted its close association with the mitochondrion, and showed putative roles of the centriolar plaques (CPs) in apicoplast segregation. These observations form the foundation for a new detailed mechanistic model of mitochondrial and apicoplast division and segregation during schizogony and pave the way for future studies into the proteins and protein complexes involved in organelle division and segregation.
PubMed: 38352445
DOI: 10.1101/2024.01.30.577899 -
Molecules (Basel, Switzerland) Jan 2024Repurposing is a universal mechanism for innovation, from the evolution of feathers to the invention of Velcro tape. Repurposing is particularly attractive for drug... (Review)
Review
Repurposing is a universal mechanism for innovation, from the evolution of feathers to the invention of Velcro tape. Repurposing is particularly attractive for drug development, given that it costs more than a billion dollars and takes longer than ten years to make a new drug from scratch. The COVID-19 pandemic has triggered a large number of drug repurposing activities. At the same time, it has highlighted potential pitfalls, in particular when concessions are made to the target product profile. Here, we discuss the pros and cons of drug repurposing for infectious diseases and analyze different ways of repurposing. We distinguish between opportunistic and rational approaches, i.e., just saving time and money by screening compounds that are already approved versus repurposing based on a particular target that is common to different pathogens. The latter can be further distinguished into divergent and convergent: points of attack that are divergent share common ancestry (e.g., prokaryotic targets in the apicoplast of malaria parasites), whereas those that are convergent arise from a shared lifestyle (e.g., the susceptibility of bacteria, parasites, and tumor cells to antifolates due to their high rate of DNA synthesis). We illustrate how such different scenarios can be capitalized on by using examples of drugs that have been repurposed to, from, or within the field of anti-infective chemotherapy.
Topics: Animals; Humans; Drug Repositioning; Pandemics; Communicable Diseases; COVID-19; Bacteria
PubMed: 38338378
DOI: 10.3390/molecules29030635 -
BioRxiv : the Preprint Server For... Jan 2024Babesiosis, caused by protozoan parasites of the genus , is an emerging tick-borne disease of significance for both human and animal health. parasites infect...
Babesiosis, caused by protozoan parasites of the genus , is an emerging tick-borne disease of significance for both human and animal health. parasites infect erythrocytes of vertebrate hosts where they develop and multiply rapidly to cause the pathological symptoms associated with the disease. The identification of various species underscores the ongoing risk of new zoonotic pathogens capable of infecting humans, a concern amplified by anthropogenic activities and environmental shifts impacting the distribution and transmission dynamics of parasites, their vectors, and reservoir hosts. One such species, MO1, previously implicated in severe cases of human babesiosis in the midwestern United States, was initially considered closely related to , the predominant agent of human babesiosis in Europe. Yet, uncertainties persist regarding whether these pathogens represent distinct variants of the same species or are entirely separate species. We show that although both MO1 and share similar genome sizes, comprising three nuclear chromosomes, one linear mitochondrial chromosome, and one circular apicoplast chromosome, major differences exist in terms of genomic sequence divergence, gene functions, transcription profiles, replication rates and susceptibility to antiparasitic drugs. Furthermore, both pathogens have evolved distinct classes of multigene families, crucial for their pathogenicity and adaptation to specific mammalian hosts. Leveraging genomic information for MO1, , and other members of the Babesiidae family within Apicomplexa provides valuable insights into the evolution, diversity, and virulence of these parasites. This knowledge serves as a critical tool in preemptively addressing the emergence and rapid transmission of more virulent strains.
PubMed: 38293033
DOI: 10.1101/2024.01.17.575932 -
Microorganisms Dec 2023is an apicomplexan protozoan parasite responsible for causing neosporosis in a range of animal species. It results in substantial economic losses in the livestock...
is an apicomplexan protozoan parasite responsible for causing neosporosis in a range of animal species. It results in substantial economic losses in the livestock industry and poses significant health risks to companion and wild animals. Central to its survival and pathogenicity is the process of cell division, which remains poorly understood in this parasite. In this study, we explored the cell division of using a combination of modern and classic imaging tools, emphasizing its pivotal role in perpetuating the parasite's life cycle and contributing to its ability to persist within host organisms. We described the intricacies of endodyogeny in , detailing the dynamics of the cell assembly and the nuclear division by ultrastructure expansion microscopy and regular confocal microscopy. Furthermore, we explored the centrosome dynamics, the centrioles and the apicoplast through the advancement of the cell cycle. Our analysis described with unprecedented detail, the endodyogeny in this parasite. By advancing our understanding of these molecular mechanisms, we aimed to inspire innovative strategies for disease management and control, with the ultimate goal of mitigating the devastating impact of neosporosis on animal health and welfare.
PubMed: 38257886
DOI: 10.3390/microorganisms12010061 -
Life (Basel, Switzerland) Jan 2024Cryptosporidiosis is the leading cause of life-threatening diarrheal infection, especially in infants. Oocysts contaminate the environment, and also, being a zoonotic... (Review)
Review
Cryptosporidiosis is the leading cause of life-threatening diarrheal infection, especially in infants. Oocysts contaminate the environment, and also, being a zoonotic disease, cryptosporidiosis is a threat to One Health. Nitazoxanide is the only FDA-approved drug, effective only in immunocompetent adults, and is not safe for infants. The absence of mitochondria and apicoplast, the presence of an electron-dense band (ED band), hindrances in its genetic and phenotypic manipulations, and its unique position inside the host cell are some challenges to the anti-cryptosporidial drug-discovery process. However, many compounds, including herbal products, have shown efficacy against during and trials. Still, the "drug of choice" against this protozoan parasite, especially in immunocompromised individuals and infants, has not yet been explored. The One-Health approach addresses this issue, focusing on the intersection of animal, human, and environmental health. The objective of this review is to provide knowledge about novel anti-cryptosporidial drug targets, available treatment options with associated limitations, and possible future shifts toward natural products to treat cryptosporidiosis. The current review is organized to address the treatment and prevention of cryptosporidiosis. An anti-cryptosporidial drug that is effective in immunocompromised individuals and infants is a necessity of our time.
PubMed: 38255695
DOI: 10.3390/life14010080 -
Veterinary Research Jan 2024Toxoplasma gondii is among the most important parasites worldwide. The apicoplast is a unique organelle shared by all Apicomplexan protozoa. Increasing lines of evidence...
Toxoplasma gondii is among the most important parasites worldwide. The apicoplast is a unique organelle shared by all Apicomplexan protozoa. Increasing lines of evidence suggest that the apicoplast possesses its own ubiquitination system. Deubiquitination is a crucial step executed by deubiquitinase (DUB) during protein ubiquitination. While multiple components of ubiquitination have been identified in T. gondii, the deubiquitinases involved remain unknown. The aim of the current study was to delineate the localization of TgOTU7 and elucidate its functions. TgOTU7 was specifically localized at the apicoplast, and its expression was largely regulated during the cell cycle. Additionally, TgOTU7 efficiently breaks down ubiquitin chains, exhibits linkage-nonspecific deubiquitinating activity and is critical for the lytic cycle and apicoplast biogenesis, similar to the transcription of the apicoplast genome and the nuclear genes encoding apicoplast-targeted proteins. Taken together, the results indicate that the newly described deubiquitinase TgOTU7 specifically localizes to the apicoplast and affects the cell growth and apicoplast homeostasis of T. gondii.
Topics: Animals; Toxoplasma; Apicoplasts; Cell Cycle; Homeostasis; Deubiquitinating Enzymes; Protozoan Proteins
PubMed: 38233899
DOI: 10.1186/s13567-023-01261-y