Plasmodium APC3 mediates chromosome condensation and cytokinesis during atypical mitosis in male gametogenesis

Richard J Wall,Aline Freville,Chris J Janse,Rita Tewari,David S Guttery,Sally Wheatley,Andrew R Bottrill,Declan Brady,David J P Ferguson,Blandine Franke-Fayard,Andrew M Fry,Mohammad Zeeshan,Hiroyuki Yamano,Anthony A Holder

doi:10.1038/s41598-018-23871-9

Abstract

The anaphase promoting complex/cyclosome (APC/C) is a highly conserved multi-subunit E3 ubiquitin ligase that controls mitotic division in eukaryotic cells by tagging cell cycle regulators for proteolysis. APC3 is a key component that contributes to APC/C function. Plasmodium, the causative agent of malaria, undergoes atypical mitotic division during its life cycle. Only a small subset of APC/C components has been identified in Plasmodium and their involvement in atypical cell division is not well understood. Here, using reverse genetics we examined the localisation and function of APC3 in Plasmodium berghei. APC3 was observed as a single focus that co-localised with the centriolar plaque during asexual cell division in schizonts, whereas it appeared as multiple foci in male gametocytes. Functional studies using gene disruption and conditional knockdown revealed essential roles of APC3 during these mitotic stages with loss resulting in a lack of chromosome condensation, abnormal cytokinesis and absence of microgamete formation. Overall, our data suggest that Plasmodium utilises unique cell cycle machinery to coordinate various processes during endomitosis, and this warrants further investigation in future studies.

Highlights

The anaphase promoting complex/cyclosome (APC/C) is a highly conserved multi-subunit E3 ubiquitin ligase that controls mitotic division in eukaryotic cells by tagging cell cycle regulators for proteolysis
It has been found that a number of highly conserved cell cycle regulators, such as cell division cycle 25 (CDC25), CDC14 and classical cyclins are absent from Plasmodium[2,3,4]
A small number of APC/C components have been identified in the apicomplexan parasite Plasmodium, namely: APC3, APC10, APC11 and CDC2015

Summary

Introduction

The anaphase promoting complex/cyclosome (APC/C) is a highly conserved multi-subunit E3 ubiquitin ligase that controls mitotic division in eukaryotic cells by tagging cell cycle regulators for proteolysis. Functional studies using gene disruption and conditional knockdown revealed essential roles of APC3 during these mitotic stages with loss resulting in a lack of chromosome condensation, abnormal cytokinesis and absence of microgamete formation. Mammalian cell division involves an open mitosis, where mitotic spindle formation is accompanied by nuclear envelope disintegration and subsequent partition of the cytoplasm during cytokinesis[5]. During the Plasmodium life cycle, there are two atypical mitotic processes: one that resembles endomitosis occurs during asexual multiplication, for example, during blood stage schizogony[6,7], and another that occurs during the sexual stage - the formation of microgametes (male progenitor sex cells) in the mosquito midgut[10]. Only four APC/C components have been identified as coded by the Plasmodium genome: APC10, APC11 and APC3 (a tetratricopeptide repeat [TPR] containing subunit), along with CDC2015

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Results

Conclusion