| 1. |
- Akkaya, Munir, et al.
(författare)
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A single-nucleotide polymorphism in a Plasmodium berghei ApiAP2 transcription factor alters the development of host immunity
- 2020
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Ingår i: Science Advances. - : American Association for the Advancement of Science. - 2375-2548. ; 6:6
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Tidskriftsartikel (refereegranskat)abstract
- The acquisition of malaria immunity is both remarkably slow and unpredictable. At present, we know little about the malaria parasite genes that influence the host's ability to mount a protective immune response. Here, we show that a single-nucleotide polymorphism (SNP) resulting in a single amino acid change (S to F) in an ApiAP2 transcription factor in the rodent malaria parasite Plasmodium berghei (Pb) NK65 allowed infected mice to mount a T helper cell 1 (T(H)1)-type immune response that controlled subsequent infections. As compared to PbNK65(S), PbNK65(F) parasites differentially expressed 46 genes, most of which are predicted to play roles in immune evasion. PbNK65(F) infections resulted in an early interferon-gamma response and a later expansion of germinal centers, resulting in high levels of infected red blood cell-specific T(H)1-type immunoglobulin G2b (IgG2b) and IgG2c antibodies. Thus, the Pb ApiAP2 transcription factor functions as a critical parasite virulence factor in malaria infections.
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| 2. |
- Mancio-Silva, Liliana, et al.
(författare)
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Nutrient sensing modulates malaria parasite virulence
- 2017
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Ingår i: Nature. - : Macmillan Publishers Ltd.. - 0028-0836 .- 1476-4687. ; 547:7662, s. 213-216
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Tidskriftsartikel (refereegranskat)abstract
- The lifestyle of intracellular pathogens, such as malaria parasites, is intimately connected to that of their host, primarily for nutrient supply. Nutrients act not only as primary sources of energy but also as regulators of gene expression, metabolism and growth, through various signalling networks that enable cells to sense and adapt to varying environmental conditions. Canonical nutrient-sensing pathways are presumed to be absent from the causative agent of malaria, Plasmodium, thus raising the question of whether these parasites can sense and cope with fluctuations in host nutrient levels. Here we show that Plasmodium blood-stage parasites actively respond to host dietary calorie alterations through rearrangement of their transcriptome accompanied by substantial adjustment of their multiplication rate. A kinome analysis combined with chemical and genetic approaches identified KIN as a critical regulator that mediates sensing of nutrients and controls a transcriptional response to the host nutritional status. KIN shares homology with SNF1/AMPKα, and yeast complementation studies suggest that it is part of a functionally conserved cellular energy-sensing pathway. Overall, these findings reveal a key parasite nutrient-sensing mechanism that is critical for modulating parasite replication and virulence.
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| 3. |
- Pino, Paco, et al.
(författare)
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A tetracycline-repressible transactivator system to study essential genes in malaria parasites
- 2012
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Ingår i: Cell Host and Microbe. - : Elsevier. - 1931-3128 .- 1934-6069. ; 12:6, s. 824-834
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Tidskriftsartikel (refereegranskat)abstract
- A major obstacle in analyzing gene function in apicomplexan parasites is the absence of a practical regulatable expression system. Here, we identified functional transcriptional activation domains within Apicomplexan AP2 (ApiAP2) family transcription factors. These ApiAP2 transactivation domains were validated in blood-, liver-, and mosquito-stage parasites and used to create a robust conditional expression system for stage-specific, tetracycline-dependent gene regulation in Toxoplasma gondii, Plasmodium berghei, and Plasmodium falciparum. To demonstrate the utility of this system, we created conditional knockdowns of two essential P. berghei genes: profilin (PRF), a protein implicated in parasite invasion, and N-myristoyltransferase (NMT), which catalyzes protein acylation. Tetracycline-induced repression of PRF and NMT expression resulted in a dramatic reduction in parasite viability. This efficient regulatable system will allow for the functional characterization of essential proteins that are found in these important parasites.
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| 4. |
- Sinha, Abhinav, et al.
(författare)
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A cascade of DNA-binding proteins for sexual commitment and development in Plasmodium
- 2014
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Ingår i: Nature. - : Macmillan Publishers Ltd.. - 0028-0836 .- 1476-4687. ; 507:7491, s. 253-257
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Tidskriftsartikel (refereegranskat)abstract
- Commitment to and completion of sexual development are essential for malaria parasites (protists of the genus Plasmodium) to be transmitted through mosquitoes. The molecular mechanism(s) responsible for commitment have been hitherto unknown. Here we show that PbAP2-G, a conserved member of the apicomplexan AP2 (ApiAP2) family of DNA-binding proteins, is essential for the commitment of asexually replicating forms to sexual development in Plasmodium berghei, a malaria parasite of rodents. PbAP2-G was identified from mutations in its encoding gene, PBANKA_143750, which account for the loss of sexual development frequently observed in parasites transmitted artificially by blood passage. Systematic gene deletion of conserved ApiAP2 genes in Plasmodium confirmed the role of PbAP2-G and revealed a second ApiAP2 member (PBANKA_103430, here termed PbAP2-G2) that significantly modulates but does not abolish gametocytogenesis, indicating that a cascade of ApiAP2 proteins are involved in commitment to the production and maturation of gametocytes. The data suggest a mechanism of commitment to gametocytogenesis in Plasmodium consistent with a positive feedback loop involving PbAP2-G that could be exploited to prevent the transmission of this pernicious parasite.
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