Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1069884 | ENA |
REPOSITORIES: ENA
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Project description:Mitosis is an important process in the cell cycle required for cells to divide. Never in mitosis (NIMA)-like kinases (NEKs) are regulators of mitotic functions in diverse organisms. Plasmodium spp, the causative agent of malaria is a divergent unicellular haploid eukaryote with some unusual features in terms of its mitotic and nuclear division cycle that presumably facilitate proliferation in varied environments. For example, during the sexual stage of male gametogenesis that occurs within the mosquito host, an atypical rapid closed endomitosis is observed. Three rounds of genome replication from 1N to 8N and successive cycles of multiple spindle formation and chromosome segregation occur within eight minutes followed by karyokinesis to generate haploid gametes. Our previous Plasmodium berghei kinome screen identified four Nek genes, of which two, NEK2 and NEK4, are required for meiosis. NEK1 is likely to be essential for mitosis in asexual blood stage schizogony in the vertebrate host, but its function during male gametogenesis is unknown. Here, we study NEK1 location and function, using live cell imaging, ultrastructure expansion microscopy (U-ExM) and electron microscopy, together with conditional gene knockdown and proteomic approaches. We report spatiotemporal NEK1 location in real-time, coordinated with microtubule organising centre (MTOC) dynamics during the unusual mitoses at various stages of the Plasmodium spp. life cycle. Knockdown studies reveal NEK1 to be an essential component of the MTOC in male cell differentiation, associated with rapid mitosis, spindle formation and kinetochore attachment. These data suggest that Plasmodium berghei NEK1 kinase is an important component of MTOC organisation and essential regulator of chromosome segregation during male gamete formation.
2024-08-08 | PXD053559 | Pride
Project description:PP1 is a conserved serine/threonine phosphatase that regulates many aspects of mitosis and meiosis, often working in concert with other phosphatases, such as CDC14 and CDC25, in model eukaryotes. However, the malaria parasite, Plasmodium spp. lacks the CDC14 and CDC25 genes. The proliferative stages of the parasite life cycle include sexual development within the mosquito vector, with male gamete formation characterized by an atypical rapid mitosis, with three rounds of DNA synthesis, successive spindle formation with clustered kinetochore, and a meiotic stage during zygote to ookinete development following fertilization. It is unclear how PP1 is involved these unusual processes. Using real-time live-cell imaging, conditional gene knockdown, RNAseq and proteomic approaches, we show that Plasmodium PP1 is involved in both chromosome segregation during mitotic exit, and establishment of cell polarity during these sexual stages, suggesting that PP1 inhibitors may block parasite transmission.
2021-07-08 | GSE164175 | GEO
Project description:PP1 is a conserved eukaryotic serine/threonine phosphatase that regulates many aspects of mitosis and meiosis, often working in concert with other phosphatases, such as CDC14 and CDC25. The proliferative stages of the parasite life cycle include sexual development within the mosquito vector, with male gamete formation characterized by an atypical rapid mitosis, consisting of three rounds of DNA synthesis, successive spindle formation with clustered kinetochores, and a meiotic stage during zygote to ookinete development following fertilization. It is unclear how PP1 is involved in these unusual processes. Using real-time live-cell imaging, conditional gene knockdown, RNA-seq and proteomic approaches, we show that Plasmodium PP1 is involved in both chromosome segregation during mitotic exit, and potentially establishment of cell polarity during zygote development in the mosquito midgut, suggesting that chemical inhibitors of PP1 may be explored for blocking parasite transmission
2021-09-10 | PXD023571 | Pride
Project description:Chromosome segregation depends on proper attachment of sister kinetochores to microtubules. Merotelic kinetochore orientation is an error which occurs when a single kinetochore is attached to microtubules emanating form opposite poles. Mechanisms preventing or correcting the merotelic attachment must operate to avoid chromosome missegregation. Pcs1 has been implicated in preventing merotelic attachment in mitosis and meiosis II. We describe here the identification of Mde4 protein which forms a complex with the Pcs1. Both Mde4 and Pcs1 localize to the central core of the centromere. Similarly to the pcs1 mutant, in the absence of mde4 lagging chromosomes are frequently observed during mitosis and meiosis II . We provide the first evidence that the lagging chromosomes in pcs1 and mde4 mutants are due to merotelic kinetochore orientation. Keywords: ChIP-chip analysis ChIP-chip analysis: In all cases, hybridization data for ChIP fraction was compared with that of SUP (supernatant) fraction. Pombe whole chromosome array was used.
2010-06-10 | E-GEOD-5257 | biostudies-arrayexpress
Project description:Chromosome segregation depends on proper attachment of sister kinetochores to microtubules. Merotelic kinetochore orientation is an error which occurs when a single kinetochore is attached to microtubules emanating form opposite poles. Mechanisms preventing or correcting the merotelic attachment must operate to avoid chromosome missegregation. Pcs1 has been implicated in preventing merotelic attachment in mitosis and meiosis II. We describe here the identification of Mde4 protein which forms a complex with the Pcs1. Both Mde4 and Pcs1 localize to the central core of the centromere. Similarly to the pcs1 mutant, in the absence of mde4 lagging chromosomes are frequently observed during mitosis and meiosis II . We provide the first evidence that the lagging chromosomes in pcs1 and mde4 mutants are due to merotelic kinetochore orientation. Keywords: ChIP-chip analysis
2007-06-18 | GSE5257 | GEO
Project description:Sexual differentiation of malaria parasites into gametocytes in the vertebrate host and subsequent gamete fertilisation in mosquitoes is essential for the spreading of the disease. The molecular processes orchestrating these transitions are far from fully understood. Here we report the first transcriptome analysis of male and female Plasmodium falciparum gametocytes coupled with a comprehensive proteome analysis. In male gametocytes there is an enrichment of proteins involved in the formation of flagellated gametes; proteins involved in DNA replication, chromatin organisation and axoneme formation. On the other hand, female gametocytes are enriched in proteins required for zygote formation and functions after fertilisation; protein-, lipid- and energy-metabolism. Integration of transcriptome and proteome data revealed 512 highly expressed maternal transcripts without corresponding protein expression indicating large scale translational repression in P. falciparum female gametocytes for the first time. Despite a high degree of conservation between Plasmodium species, 260 of these ârepressed transcriptsâ have not been previously described. Moreover, for some of these genes, protein expression is only reported in oocysts and sporozoites indicating that repressed transcripts can be partitioned into short- and long-term storage. Finally, these data sets provide an essential resource for identification of vaccine/drug targets and for further mechanistic studies. Examining the transcriptome of p47-mCherry positive female and pDynGFP positive (or double positive) male gametocytes by RNA-seq.
2016-06-28 | E-GEOD-75795 | biostudies-arrayexpress
Project description:Sexual differentiation of malaria parasites into gametocytes in the vertebrate host and subsequent gamete fertilisation in mosquitoes is essential for the spreading of the disease. The molecular processes orchestrating these transitions are far from fully understood. Here we report the first transcriptome analysis of male and female Plasmodium falciparum gametocytes coupled with a comprehensive proteome analysis. In male gametocytes there is an enrichment of proteins involved in the formation of flagellated gametes; proteins involved in DNA replication, chromatin organisation and axoneme formation. On the other hand, female gametocytes are enriched in proteins required for zygote formation and functions after fertilisation; protein-, lipid- and energy-metabolism. Integration of transcriptome and proteome data revealed 512 highly expressed maternal transcripts without corresponding protein expression indicating large scale translational repression in P. falciparum female gametocytes for the first time. Despite a high degree of conservation between Plasmodium species, 260 of these ‘repressed transcripts’ have not been previously described. Moreover, for some of these genes, protein expression is only reported in oocysts and sporozoites indicating that repressed transcripts can be partitioned into short- and long-term storage. Finally, these data sets provide an essential resource for identification of vaccine/drug targets and for further mechanistic studies.
2016-06-28 | GSE75795 | GEO
Project description:Precise regulation of kinetochore-microtubules is essential for successful chromosome segregation. Central to this regulation is Aurora B kinase, which phosphorylates kinetochore substrates to promote microtubule turnover. A critical target of Aurora B is the N-terminal “tail” domain of Hec1/NDC80, which is a component of the NDC80 complex, a force-transducing link between kinetochores and microtubules. While Aurora B is regarded as the “master regulator” of kinetochore-microtubule attachment, it is likely that other mitotic kinases contribute to Hec1phosphorylation. Here we show that Aurora A kinase phosphorylates the tail domain of Hec1 at Serine 69, a previously uncharacterized phosphorylation target site, and plays an important role in controlling kinetochore-microtubule attachment dynamics. Using phospho-specific antibodies, Hec1 phospho-deficient mutants, and kinase inhibitors, we demonstrate that Aurora A is required for the regulation of kinetochore-microtubule dynamics of metaphase chromosomes and identify Hec1 Serine 69 as a critical Aurora A substrate for this regulation. Additionally, we demonstrate that Aurora A kinase associates with INCENP during mitosis and that INCENP is competent to drive accumulation of the kinase to the centromere region of mitotic chromosomes. These findings reveal that both Aurora A and Aurora B contribute to kinetochore-microtubule attachment dynamics, and they uncover an unexpected role for Aurora A in mitosis.
2017-11-28 | PXD006892 | Pride
Project description:Kinetochores form the link between chromosomes and microtubules of the mitotic spindle. The heterodecameric Dam1 complex (Dam1c) is a major component of the S. cerevisiae outer kinetochore, assembling into 3 MDa-sized microtubule-embracing rings, but how ring assembly is specifically initiated at kinetochores remains to be understood. Here, we describe a molecular pathway that provides local control of ring assembly during the establishment of sister kinetochore bi-orientation. We show that Dam1c and the general microtubule plus-end-associated protein (+TIP) Bim1/EB1 form a stable complex depending on a conserved motif in the Duo1 subunit of Dam1c. EM analyses reveal that Bim1 crosslinks protrusion domains of adjacent Dam1c heterodecamers and promotes the formation of oligomers with defined curvature. Disruption of the Dam1c-Bim1 interaction impairs kinetochore localization of Dam1c in metaphase and delays mitosis. Phosphorylation promotes Dam1c-Bim1 binding by relieving an intramolecular inhibition of the Dam1 C-terminus. In addition, Bim1 recruits Bik1/CLIP-170 to Dam1c and induces formation of full rings even in the absence of microtubules. Our data help to explain how new kinetochore end-on attachments are formed during the process of attachment error correction.
2021-06-28 | PXD026935 | Pride
Project description:Plasmodium, the malaria parasite, undergoes a complex life cycle, which alternates between a vertebrate host and a mosquito vector of the genus Anopheles. In red blood cells of the vertebrate host, Plasmodium multiplies asexually or differentiates into gamete precursors, the male and female gametocytes, responsible for parasite transmission. Sexual stage maturation occurs in the midgut of the mosquito vector, where male and female gametes egress from the host erythrocyte to form a zygote. Gamete egress entails the successive rupture of two membranes surrounding the parasite, the parasitophorous vacuole membrane and the erythrocyte plasma membrane.
In this study, we applied a proteomic approach to identify proteins differentially released/secreted by female and male gametocytes of the rodent Plasmodium berghei activated to form gametes. We compared secreted molecules of the wild type gametocytes with those of a transgenic line defective in male gamete maturation and egress. This enabled us to provide a comprehensive dataset of egress-related molecules and their gender specificity. Using specific antibodies, we validated eleven candidate molecules, predicted as either gender-specific or common to both male and female gametocytes. All of them localize to punctuate, vesicle-like structures that relocate to cell periphery upon activation, but only three of them localize to the gametocyte-specific secretory vesicles named osmiophilic bodies. Our results confirm that the egress process involves a tightly coordinated secretory apparatus that includes different types of vesicles and may put the basis for functional studies aimed at designing novel transmission-blocking molecules.
2020-06-30 | MSV000085650 | MassIVE