Plasmodium kinesin-8X associates with mitotic spindles and is essential for oocyst development during parasite proliferation and transmission

Abstract

Kinesin-8 proteins are microtubule motors that are often involved in regulation of mitotic spindle length and chromosome alignment. They move towards the plus ends of spindle microtubules and regulate the dynamics of these ends due, at least in some species, to their microtubule depolymerization activity. Plasmodium spp. exhibit an atypical endomitotic cell division in which chromosome condensation and spindle dynamics in the different proliferative stages are not well understood. Genome-wide shared orthology analysis of Plasmodium spp. revealed the presence of two kinesin-8 motor proteins, kinesin-8X and kinesin-8B. Here we studied the biochemical properties of kinesin-8X and its role in parasite proliferation. In vitro, kinesin-8X has motility and depolymerization activities like other kinesin-8 motors. To understand the role of Plasmodium kinesin-8X in cell division, we used fluorescence-tagging and live cell imaging to define its location, and gene targeting to analyse its function, during all proliferative stages of the rodent malaria parasite P. berghei life cycle. The results revealed a spatio-temporal involvement of kinesin-8X in spindle dynamics and an association with both mitotic and meiotic spindles and the putative microtubule organising centre (MTOC). Deletion of the kinesin-8X gene revealed a defect in oocyst development, confirmed by ultrastructural studies, suggesting that this protein is required for oocyst development and sporogony. Transcriptome analysis of Δkinesin-8X gametocytes revealed modulated expression of genes involved mainly in microtubule-based processes, chromosome organisation and the regulation of gene expression, supporting a role for kinesin-8X in cell division. Kinesin-8X is thus required for parasite proliferation within the mosquito and for transmission to the vertebrate host.

Plasmodium bergheikinesin-5 associates with the spindle apparatus during cell division and is important for efficient production of infectious sporozoites

“…5B). This mirrors what has been seen in electron microscopy studies: nuclear spindles radiate from the nuclear poles, with attached kinetochores within an intact nuclear membrane during oocyst development [30,32].…”

“…The loss of kinesin-5 may have been compensated for by the over-expression of another member of the kinesin family, therefore we analysed the transcript level of kinesin-8B, kinesin-8X and kinesin-13 in gametocytes of Δ kinesin-5 parasites. These kinesins are highly expressed in gametocytes and have important role during male gametogony [23,30]. We found that the kinesin-13 transcript level was significantly upregulated ( Fig.…”

“…As cell division in Plasmodium is atypical, so the molecules regulating cell division are also divergent from those of higher eukaryotes [24][25][26][27]. The large family of kinesins includes molecular motors that are essential for several processes during cell division [28,29], and in Plasmodium berghei there are nine kinesin genes, including two kinesin-8 genes that are important in cell division and male gamete formation [23,30]. There is a single Plasmodium kinesin-5, and since this protein plays an important role during cell proliferation in many eukaryotes, and is considered as a strong target for the development of therapeutics against many diseases including malaria [31], we decided to study its role during cell division in the malaria parasite.…”

Plasmodium berghei Kinesin-5 Associates With the Spindle Apparatus During Cell Division and Is Important for Efficient Production of Infectious Sporozoites

“…The loss of kinesin-5 may have been compensated for by the over-expression of another member of the kinesin family, therefore we analyzed the transcript level of kinesin-8B, kinesin-8X and kinesin-13 in gametocytes of Δkinesin-5 parasites. These kinesins are highly expressed in gametocytes and have important role during male gametogony ( Zeeshan et al., 2019a ; Zeeshan et al., 2019b ). We found that the kinesin-13 transcript level was significantly upregulated ( Figure 1M ), suggesting that higher levels of kinesin-13 may - in some way - compensate for the kinesin-5 deletion.…”

“…As cell division in Plasmodium is atypical, so the molecules regulating cell division are also divergent from those of higher eukaryotes ( Tewari et al., 2010 ; Guttery et al., 2014 ; Roques et al., 2015 ; Wall et al., 2018 ). The large family of kinesins includes molecular motors that are essential for several processes during cell division ( Wordeman, 2010 ; Yount et al., 2015 ), and in Plasmodium berghei there are nine kinesin genes, including two kinesin-8 genes that are important in cell division and male gamete formation ( Zeeshan et al., 2019a ; Zeeshan et al., 2019b ). There is a single Plasmodium kinesin-5, and since this protein plays an important role during cell proliferation in many eukaryotes, and is considered as a strong target for the development of therapeutics against many diseases including malaria ( Liu et al., 2014 ), we decided to study its role during cell division in the malaria parasite.…”