| 1. |
- Dziedziech, Alexis, 1991-, et al.
(författare)
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Convergent evolution of mammalian inflammatory cell death mechanism, pyroptosis in Drosophila melanogaster
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Pyroptosis has been described in mammalian systems to be a form of programmed cell death that is important in immune function through the subsequent release of cytokines upon cell bursting. This form of cell death has been increasingly well-characterized in mammals but there has been little evidence for the existence of pyroptosis across phyla. Here we provide evidence for convergent evolution of pyroptosis in an in vivo immune scenario in Drosophila melanogaster. Crystal cells, a type of insect blood cell, were recruited to the wound and ruptured subsequently releasing their cytosolic content in a caspase-dependent manner. This inflammatory based programmed cell death mechanism fits the features of pyroptosis, never before described in an in vivo immune scenario in insects. Further, we unveil key players upstream in the activation of cell death in these cells., Thus, Drosophila may be a suitable model for studying the functional significance of pyroptosis in the innate immune system.
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| 2. |
- Dziedziech, Alexis, 1991-, et al.
(författare)
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Proto-pyroptosis : An Ancestral Origin for Mammalian Inflammatory Cell Death Mechanism in Drosophila melanogaster
- 2022
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 434:4
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Tidskriftsartikel (refereegranskat)abstract
- Pyroptosis has been described in mammalian systems to be a form of programmed cell death that is important in immune function through the subsequent release of cytokines and immune effectors upon cell bursting. This form of cell death has been increasingly well-characterized in mammals and can occur using alternative routes however, across phyla, there has been little evidence for the existence of pyroptosis. Here we provide evidence for an ancient origin of pyroptosis in an in vivo immune scenario in Drosophila melanogaster. Crystal cells, a type of insect blood cell, were recruited to wounds and ruptured subsequently releasing their cytosolic content in a caspase-dependent manner. This inflammatory-based programmed cell death mechanism fits the features of pyroptosis, never before described in an in vivo immune scenario in insects and relies on ancient apoptotic machinery to induce proto-pyroptosis. Further, we unveil key players upstream in the activation of cell death in these cells including the apoptosome which may play an alternative role akin to the inflammasome in proto-pyroptosis. Thus, Drosophila may be a suitable model for studying the functional significance of pyroptosis in the innate immune system.
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| 3. |
- Dziedziech, Alexis, 1991-
(författare)
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Timing Matters : Wounding and entomopathogenic nematode infection kinetics
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over time, insects have developed complex strategies to defend themselves against presenting threats. However, in the evolutionary arms race of survival, pathogens have adapted to quickly overcome the immune response mounted by the host. In this thesis, we assess how quickly entomopathogenic nematodes (EPNs) can overcome the host, Drosophila melanogaster. We then look at the clotting reaction at a hypothetical point of entry for the nematode and bring resolution to the order of protein interaction focusing on three proteins important in the anti-nematode defense. Finally, we look closer into detail at how crystal cells secrete one of those proteins, prophenoloxidase (PPOII) using a mode of programmed cell death. (Paper I) In the course of EPN infection, little was known about how quickly the worms can overcome the host immune system. Here we found that after penetrating the host, EPNs cause septicemia within 4 to 6 hours. (Paper II) Three proteins, Glutactin (Glt), Transglutaminase (Tg), and PPOII have been found to be important in the anti-nematode response. Here we created GFP-tagged fly constructs to follow their role in clot formation. In early clot formation, Tg was immediately secreted from hemocytes though it was localized around the cell membrane, Glt then entered clot fibers followed by PPOII which acted in late clot formation. (Paper III) Here we looked closer into Tg and PPOII secretion variability. PPOII from immature, but not mature crystal cells colocalized with a membrane marker. Tg, when driven with a pan tissue driver, was found located in clotting fibers, in contrast with paper II. (Paper IV) In an in vivo immune scenario, crystal cells were recruited to the wound site and burst rapidly in a caspase-dependent manner. We demonstrate that the mode of programmed cell death, pyroptosis, exists in Drosophila by way of convergent evolution.This thesis brings to light the variation found within the infection process for EPNs as well as the clotting response based on larval age, tissue type, and the maturity of a single cell type. Timing in each of these immune scenarios can give very different indications about the kind of immune response mounted and even the role of an individual cell.
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| 4. |
- Hildebrandt, Franziska, 1994-, et al.
(författare)
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scDual-Seq of Toxoplasma gondii-infected mouse BMDCs reveals heterogeneity and differential infection dynamics
- 2023
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Ingår i: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Dendritic cells and macrophages are integral parts of the innate immune system and gatekeepers against infection. The protozoan pathogen, Toxoplasma gondii, is known to hijack host immune cells and modulate their immune response, making it a compelling model to study host-pathogen interactions. Here we utilize single cell Dual RNA-seq to parse out heterogeneous transcription of mouse bone marrow-derived dendritic cells (BMDCs) infected with two distinct genotypes of T. gondii parasites, over multiple time points post infection. We show that the BMDCs elicit differential responses towards T. gondii infection and that the two parasite lineages distinctly manipulate subpopulations of infected BMDCs. Co-expression networks define host and parasite genes, with implications for modulation of host immunity. Integrative analysis validates previously established immune pathways and additionally, suggests novel candidate genes involved in host-pathogen interactions. Altogether, this study provides a comprehensive resource for characterizing host-pathogen interplay at high-resolution.
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| 5. |
- Mohammed, Mubasher, Msc, et al.
(författare)
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Single-cell transcriptomics reveals transcriptional programs underlying male and female cell fate during Plasmodium falciparum gametocytogenesis
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Apicomplexa constitute a large phylum of parasitic protozoa with complex life cycles that typically include meiotic sex. The life cycle of the malaria parasite, Plasmodium falciparum, includes obligate transition and stage development between a human and mosquito host. Asexual parasite replication in the human erythrocytes is followed by differentiation which leads to the formation of a precursor gamete stage, referred to as gametocytes. The gametocyte stage is solely responsible for malaria transmission into the mosquito vector where gamete fusion followed by meiosis occurs. How the parasite differentiates into male and female gametocytes in the absence of sex chromosomes largely remains an open question. Here we combine FACS-based cell enrichment of a gametocyte reporter line followed by single-cell RNA-seq, to enable targeted characterization of the entire gametocyte developmental stage. Our data defines differential transcriptional programs during male and female gametocyte development and highlights a bifurcation point for sexual cell fate. We perform prediction analyses of novel candidate driver genes underlying P. falciparum male and female lineage development. Our data indicate that a large panel of genes linked to the inner membrane complex, known to be involved in morphological life cycle changes, appears to be uniquely expressed in the female gametocyte lineage. Additionally, we delineate the timing of expression of members of the ApiAP2 family of transcription factors and predict their specificity in male and female P. falciparum gametocyte development. A motif-driven gene regulatory network analysis indicates a major role for AP2-G5 in downstream gene regulation along the male lineage developmental trajectory. In total, we anticipate that this study provides the malaria community with an important resource for the development of transmission-blocking intervention strategies.
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| 6. |
- Mohammed, Mubasher, Msc, et al.
(författare)
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Single-Cell Transcriptomics To Define Plasmodium falciparum Stage Transition in the Mosquito Midgut
- 2023
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Ingår i: Microbiology Spectrum. - : American Society for Microbiology. - 2165-0497. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- Malaria inflicts the highest rate of morbidity and mortality among the vector-borne diseases. The dramatic bottleneck of parasite numbers that occurs in the gut of the obligatory mosquito vector provides a promising target for novel control strategies. Using single-cell transcriptomics, we analyzed Plasmodium falciparum development in the mosquito gut, from unfertilized female gametes through the first 20 h after blood feeding, including the zygote and ookinete stages. This study revealed the temporal gene expression of the ApiAP2 family of transcription factors and of parasite stress genes in response to the harsh environment of the mosquito midgut. Further, employing structural protein prediction analyses, we found several upregulated genes predicted to encode intrinsically disordered proteins (IDPs), a category of proteins known for their importance in regulation of transcription, translation, and protein-protein interactions. IDPs are known for their antigenic properties and may serve as suitable targets for antibody- or peptide-based transmission suppression strategies. In total, this study uncovers the P. falciparum transcriptome from early to late parasite development in the mosquito midgut, inside its natural vector, which provides an important resource for future malaria transmission-blocking initiatives.
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