Biology subjects

Adderley, J.

Publications and source records attributed to Adderley, J..

4 recordsLinked to original sources

bioRxiv2023

Plasmodium falciparum MORC protein modulates gene expression through interaction with heterochromatin

Dynamic control of gene expression is critical for blood stage development of malaria parasites. Here, we used multi-omic analyses to investigate transcriptional regulation by the chromatin-associated microrchidia protein, MORC, during asexual blood stage development of the human malaria parasite Plasmodium falciparum. We show that PfMORC (PF3D7_1468100) interacts with a suite of nuclear proteins, including APETALA2 (AP2) transcription factors (PfAP2-G5, PfAP2-O5, PfAP2-I, PF3D7_0420300, PF3D7_0613800, PF3D7_1107800, and PF3D7_1239200), a DNA helicase DS60 (PF3D7_1227100), and other chromatin remodelers (PfCHD1 and PfEELM2). Transcriptomic analysis of PfMORCHA-glmS knockdown parasites revealed 163 differentially expressed genes belonging to hypervariable multigene families, along with upregulation of genes mostly involved in host cell invasion. In vivo genome-wide chromatin occupancy analysis during both trophozoite and schizont stages of development demonstrates that PfMORC is recruited to repressed, multigene families, including the var genes in subtelomeric chromosomal regions. Collectively, we find that PfMORC is found in chromatin complexes that play a role in the epigenetic control of asexual blood stage transcriptional regulation and chromatin organization.

microbiology↗

bioRxiv2023

Mammalian cells internalize bacteriophages and utilize them as a food source to enhance cellular growth and survival

There is a growing appreciation that the direct interaction between bacteriophages and the mammalian host can facilitate diverse and unexplored symbioses. Yet the impact these bacteriophages may have on mammalian cellular and immunological processes is poorly understood. Here we applied highly purified phage T4, free from bacterial by-products and endotoxins to mammalian cells and analyzed the cellular responses using luciferase reporter and antibody microarray assays. Phage preparations were applied in vitro to either A549 lung epithelial cells, MDCK-I kidney cells, or primary mouse bone marrow derived macrophages with the phage-free supernatant serving as a comparative control. Highly purified T4 phages were rapidly internalized by mammalian cells and accumulated within macropinosomes but did not activate the inflammatory DNA response TLR9 or cGAS-STING pathways. Following eight hours of incubation with T4 phage, whole cell lysates were analyzed via antibody microarray that detected expression and phosphorylation levels of human signaling proteins. T4 phage internalization led to the activation of AKT-dependent pathways, resulting in an increase in cell metabolism, survival, and actin reorganization, the last being critical for macropinocytosis and potentially regulating a positive feedback loop to drive further phage internalization. T4 phages additionally down-regulated CDK1 and its downstream effectors, leading to an inhibition of cell cycle progression and an increase in cellular growth through a prolonged G1 phase. These interactions demonstrate that highly purified T4 phages do not activate DNA-mediated inflammatory pathways but do trigger protein phosphorylation cascades that promote cellular growth and survival. We conclude that mammalian cells are internalizing bacteriophages as a food source to promote cellular growth and metabolism.

microbiology↗

bioRxiv2021

Network analysis of large phospho-signalling datasets: application to Plasmodium-erythrocyte interactions

Phosphorylation based signalling is a complicated and intertwined series of pathways critical to all domains of life. This interconnectivity, though essential to life, makes understanding and decoding the interactions difficult. Large datasets of phosphorylation interactions through the activity of kinases on their numerous effectors are now being generated, however interpretation of the network environment remains challenging. In humans, many phosphorylation interactions have been identified across published works to form the known phosphorylation interaction network. We overlayed phosphorylation datasets onto this network which provided information to each of the connections. To analyse the datasets now mapped into a network, we designed a pathway analysis that uses random walks to identify chains of phosphorylation events occurring much more or much less frequently than expected. This analysis highlights pathways of phosphorylation that work synergistically, providing a rapid interpretation of the most critical pathways in a given dataset. Here we used datasets of human red blood cells infected with the notable stages of Plasmodium falciparum asexual development. The analysis identified several known signalling interactions, and additional interactions which could form the basis of numerous future studies. The network analysis designed here is widely applicable to any comparative phosphorylation dataset across infection and disease and can provide a rapid and reliable analysis to guide validation studies.

microbiology↗

bioRxiv2020

Signalome-wide assessment of erythrocyte response to Plasmodium reveals novel targets for host-directed antimalarial intervention

Intracellular pathogens are known to mobilise host signaling pathways to manipulate gene expression in their host cell to promote their own survival. Surprisingly, evidence is emerging that specific 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 by providing a comprehensive and dynamic assessment of host erythrocyte signaling during the course of infection with Plasmodium falciparum. We used an antibody microarray that comprises 878 antibodies directed against human signaling proteins, >600 of which are phospho-specific, to interrogate the status of host erythrocyte signaling pathways at three stages of parasite development during the asexual cycle. This confirmed the pre-existing fragmentary data on the activation of a PAK-MEK pathway, and revealed the modulation of a large number of additional signaling elements during infection. We focussed on the receptor tyrosine kinase c-MET, also known as the hepatocyte growth factor receptor, and the MAP kinase pathway component B-Raf that is reported to lie downstream of c-MET in a number of cell types. Array data validated by Western blotting revealed that activation sites of c-MET are phosphorylated in trophozoite-infected erythrocytes, and we show that treatment of parasite cultures with c-MET or B-Raf selective inhibitors have nanomolar potency against in vitro proliferation of P. falciparum and the phylogenetically distant species P. knowlesi. Furthermore, we demonstrate that a c-MET inhibitor impairs in vivo proliferation of the rodent malaria parasite P. berghei in mice. Overall, we provide a comprehensive dataset on the modulation of host erythrocyte signaling during infection with malaria parasites, as well as a proof of concept that human signaling kinases identified as activated by malaria infection represent attractive targets for antimalarial intervention.

microbiology↗