ORCID Profile
0000-0003-1716-168X
Current Organisation
Umeå University
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 23-08-2019
Abstract: Several species of the parasite Plasmodium cause human malarial diseases, and, despite determined control efforts, a huge global disease burden remains. Howick et al. present a single-cell analysis of transcription across the malaria parasite life cycle (see the Perspective by Winzeler). Single-cell transcriptomes generated from 10 different life-cycle stages of the rodent-model malaria parasite P. berghei identified 20 “modules” among 5156 core transcriptome genes. These clusters enabled functional assignment of hypothetical and conserved genes, and they hint at further substructure of established life-cycle stages. The atlas also allowed for P. falciparum and P. malariae transcriptomes from patient isolates to be deconvoluted and for classification of parasitemia according to developmental stage. Science , this issue p. eaaw2619 see also p. 753
Publisher: Springer Science and Business Media LLC
Date: 22-06-2016
Publisher: American Association for the Advancement of Science (AAAS)
Date: 31-03-2017
DOI: 10.1126/SCIIMMUNOL.AAL2192
Abstract: Computational modeling defines T helper cell differentiation toward multiple fates during experimental malaria.
Publisher: Public Library of Science (PLoS)
Date: 21-11-2013
Publisher: Public Library of Science (PLoS)
Date: 25-01-2011
Publisher: Cold Spring Harbor Laboratory
Date: 30-10-2020
DOI: 10.1101/2020.10.28.360123
Abstract: Malaria is a mosquito-borne disease caused by apicomplexan parasites of the genus Plasmodium. Completion of the parasite’s life cycle depends on the transmission of sexual stages, the gametocytes, from an infected human host to the mosquito vector. Sexual commitment occurs in only a small fraction of asexual blood stage parasites and is initiated by external cues. The gametocyte development protein 1 (GDV1) has been described as a key facilitator to trigger sexual commitment. GDV1 interacts with the silencing factor heterochromatin protein 1 (HP1), leading to its dissociation from heterochromatic DNA at the genomic locus encoding AP2-G, the master transcription factor of gametocytogenesis. How this process is regulated is not known. In this study we have addressed the role of protein kinases implicated in gametocyte development. From a pool of available protein kinase KO lines, we identified two kinase knockout lines which fail to produce gametocytes. However, independent genetic verification revealed that both kinases are not required for gametocytogenesis but both lines harbour the same mutation that leads to a truncation in the extreme C-terminus of GDV1. Introduction of the identified nonsense mutation into the genome of wild type parasite lines replicates the observed phenotype. Using a GDV1 overexpression line we show that the truncation in the GDV1 C-terminus does neither interfere with the nuclear import of GDV1 nor its interaction with HP1 in vitro , but appears important to sustain GDV1 protein levels and thereby sexual commitment. Transmission of malaria causing Plasmodium species by mosquitos requires the parasite to change from a continuously growing asexual parasite form growing in the blood, to a sexually differentiated form, the gametocyte. Only a small subset of asexual parasites differentiates into gametocytes that are taken up by the mosquito. Transmission represents a bottleneck in the lifecycle of the parasite, so a molecular understanding of the events that lead to stage conversion may identify novel intervention points. Here we screened a subset of kinases we hypothesized to play a role in this process. While we did not identify kinases required for sexual conversion, we identified a mutation in the C-terminus of the Gametocyte Development 1 protein (GDV1), which abrogates sexual development. The mutation destabilises the protein but not its interaction with its cognate binding partner HP1. This suggest an important role for the GDV1 C-terminus beyond trafficking and protein stability.
Publisher: Springer Science and Business Media LLC
Date: 12-05-2016
Publisher: Elsevier BV
Date: 02-2023
Publisher: Springer Science and Business Media LLC
Date: 11-08-2020
DOI: 10.1038/S41467-020-17829-7
Abstract: Intracellular pathogens mobilize host signaling pathways of their host cell to promote their own survival. Evidence is emerging that signal transduction elements are activated in a-nucleated erythrocytes in response to infection with malaria parasites, but the extent of this phenomenon remains unknown. Here, we fill this knowledge gap through a comprehensive and dynamic assessment of host erythrocyte signaling during infection with Plasmodium falciparum . We used arrays of 878 antibodies directed against human signaling proteins to interrogate the activation status of host erythrocyte phospho-signaling pathways at three blood stages of parasite asexual development. This analysis reveals a dynamic modulation of many host signalling proteins across parasite development. Here we focus on the hepatocyte growth factor receptor (c-MET) and the MAP kinase pathway component B-Raf, providing a proof of concept that human signaling kinases identified as activated by malaria infection represent attractive targets for antimalarial intervention.
Publisher: Springer Science and Business Media LLC
Date: 12-10-2018
DOI: 10.1038/S41467-018-06733-W
Abstract: In malaria parasites, evolution of parasitism has been linked to functional optimisation. Despite this optimisation, most members of a calcium-dependent protein kinase (CDPK) family show genetic redundancy during erythrocytic proliferation. To identify relationships between phospho-signalling pathways, we here screen 294 genetic interactions among protein kinases in Plasmodium berghei . This reveals a synthetic negative interaction between a hypomorphic allele of the protein kinase G (PKG) and CDPK4 to control erythrocyte invasion which is conserved in P. falciparum . CDPK4 becomes critical when PKG-dependent calcium signals are attenuated to phosphorylate proteins important for the stability of the inner membrane complex, which serves as an anchor for the acto-myosin motor required for motility and invasion. Finally, we show that multiple kinases functionally complement CDPK4 during erythrocytic proliferation and transmission to the mosquito. This study reveals how CDPKs are wired within a stage-transcending signalling network to control motility and host cell invasion in malaria parasites.
Publisher: Elsevier BV
Date: 07-2009
Publisher: Elsevier BV
Date: 09-2005
Publisher: Elsevier BV
Date: 12-2005
DOI: 10.1016/J.BBAPAP.2005.08.027
Abstract: The surge of interest in protein kinases as targets for chemotherapeutic intervention in a number of diseases such as cancer and neurodegenerative disorders has stimulated research aimed at determining whether enzymes of this class might also be considered as targets in the context of diseases caused by parasitic protists. Here, we present an overview of recent developments in this field, concentrating (i) on the benefits gained from the availability of genomic databases for a number of parasitic protozoa, (ii) on the emerging field of structure-aided design of inhibitors targeting protein kinases of parasitic protists, (iii) on the concept known as transmission-blockade, whereby kinases implicated in the development of the parasite in their arthropod vector might be targeted to interfere with disease transmission, and (iv) on the possibility of controlling parasitic diseases through the inhibition of host cell protein kinases that are required for the establishment of infection by the parasites.
Publisher: Elsevier BV
Date: 12-2008
Abstract: Protein kinases (PKs) play crucial roles in the control of proliferation and differentiation in eukaryotic cells. Research on protein phosphorylation has expanded tremendously in the past few years, in part as a consequence of the realization that PKs represent attractive drug targets in a variety of diseases. Activity in Plasmodium PK research has followed this trend, and several reports on various aspects of this subject were delivered at the Molecular Approaches to Malaria 2008 meeting (MAM2008), a sharp increase from the previous meeting. Here, the authors of most of these communications join to propose an integrated update of the development of the rapidly expanding field of Plasmodium kinomics.
Publisher: Cold Spring Harbor Laboratory
Date: 22-01-2019
DOI: 10.1101/527556
Abstract: Malaria parasites adopt a remarkable variety of morphological life stages as they transition through multiple mammalian host and mosquito vector environments. Here we profile the single-cell transcriptomes of thousands of in idual parasites, deriving the first high-resolution transcriptional atlas of the entire Plasmodium berghei life cycle. We then use our atlas to precisely define developmental stages of single cells from three different human malaria parasite species, including parasites isolated directly from infected in iduals. The Malaria Cell Atlas provides both a comprehensive view of gene usage in a complex eukaryotic parasite and an open access reference data set for the study of malaria parasites.
Publisher: Cold Spring Harbor Laboratory
Date: 04-08-2021
DOI: 10.1101/2021.08.04.455056
Abstract: The transmission of malaria parasites from vertebrate host to mosquito vector requires a developmental switch in asexually iding blood-stage parasites to sexual reproduction. In Plasmodium berghei the transcription factor AP2-G is required and sufficient for this switch, but how a particular sex is determined in a haploid parasite remains unknown. Using a global screen of barcoded mutants, we here identify ten genes essential for the formation of either male or female sexual forms and validate their importance for transmission. High-resolution single-cell transcriptomics of wild-type and mutant parasites portrays the developmental bifurcation and reveals a regulatory cascade of putative gene functions in determination and subsequent differentiation of each sex. A male-determining gene with a LOTUS/OST-HTH domain points towards unexpected conservation of molecular mechanisms of gametogenesis in animals and a distantly related eukaryotic parasite.
Publisher: Springer Science and Business Media LLC
Date: 05-2010
DOI: 10.1038/NSMB0510-541
Publisher: Wiley
Date: 31-08-2005
DOI: 10.1111/J.1365-2958.2005.04793.X
Abstract: The transmission of malaria parasites to the mosquito depends critically on the rapid initiation of sexual reproduction in response to triggers from the mosquito midgut environment. We here identify an essential function for an atypical mitogen-activated protein kinase of the rodent malaria parasite Plasmodium berghei, Pbmap-2, in male sexual differentiation and parasite transmission to the mosquito. A deletion mutant no longer expressing the Pbmap-2 protein develops as wild type throughout the asexual erythrocytic phase of the life cycle. Gametocytes, the sexual transmission stages, form normally and respond in vitro to the appropriate environmental cues by rounding up and emerging from their host cells. However, microgametocytes fail to release flagellated microgametes. Female development is not affected, as judged by the ability of macrogametes to become cross-fertilized by microgametes from a donor strain. Cellular differentiation of Pbmap-2 KO microgametocytes is blocked at a late stage of male gamete formation, after replication and mitoses have been completed and axonemes have been assembled. These data demonstrate a function for Pbmap-2 in initiating cytokinesis and axoneme motility, possibly downstream of a cell cycle checkpoint for the completion of replication and/or mitosis, which are extraordinarily rapid in the male gametocyte.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Oliver Billker.