Inducing controlled cell cycle arrest and re-entry during asexual proliferation ofPlasmodium falciparummalaria parasites

• DOI: 10.1101/368431
• Publication Date: 2018-07-13T07:57:20Z
• Authors: Riëtte van Biljon; Jandeli Niemand; Roelof van Wyk; Katherine Clark; Bianca Verlinden; Clarissa Abrie; Hilde von Grüning; Werner Smidt; Annél Smit; Janette Reader; Heather Painter; Manuel Llinás; Christian Doerig; Lyn-Marié Birkholtz
• Keywords: DNA Replication; 0303 health sciences; Eflornithine; Malaria parasites; Cell Cycle; Plasmodium falciparum; Protozoan Proteins; Depletion of polyamines; Article; 3. Good health; DNA-Binding Proteins; 03 medical and health sciences; Gene Expression Regulation; Synchronisation; Cell cycle progression; Polyamines; NIMA-Related Kinases; DL-α-difluoromethylornithine (DFMO); Transcription Factors

ABSTRACTThe life cycle of the malaria parasitePlasmodium falciparumis tightly regulated, oscillating between stages of intense proliferation and quiescence. Cyclic 48-hour asexual replication ofPlasmodiumis markedly different from cell division in higher eukaryotes, and mechanistically poorly understood. Here, we report tight synchronisation of malaria parasites during the early phases of the cell cycle by exposure to DL-α-difluoromethylornithine (DFMO), which results in the depletion of polyamines. This induces an inescapable cell cycle arrest in G1(~15 hours post-invasion) by blocking G1/S transition. Cell cycle-arrested parasites enter a quiescent G0-like state but, upon addition of exogenous polyamines, re-initiate their cell cycle in a coordinated fashion. This ability to halt malaria parasites at a specific point in their cell cycle, and to subsequently trigger re-entry into the cell cycle, provides a valuable framework to investigate cell cycle regulation in these parasites. We therefore used gene expression analyses to show that re-entry into the cell cycle involves expression of Ca2+-sensitive (cdpk4andpk2)and mitotic kinases (nimaandark2),with deregulation of the pre-replicative complex associated with expression ofpk2. Changes in gene expression could be driven through transcription factors MYB1 and two ApiAP2 family members. This new approach to parasite synchronisation therefore expands our currently limited toolkit to investigate cell cycle regulation in malaria parasites.