Absence of a conventional spindle mitotic checkpoint in the binucleated single-celled parasite Giardia intestinalis
Jazyk angličtina Země Německo Médium print-electronic
Typ dokumentu časopisecké články
PubMed
27496292
DOI
10.1016/j.ejcb.2016.07.003
PII: S0171-9335(16)30060-7
Knihovny.cz E-zdroje
- Klíčová slova
- Albendazole, Giardia, Kinetochore, Mad2, Single-celled eukaryote, Spindle assembly checkpoint,
- MeSH
- aparát dělícího vřeténka fyziologie MeSH
- Giardia lamblia genetika izolace a purifikace fyziologie MeSH
- kinetochory fyziologie MeSH
- kontrolní body M fáze buněčného cyklu fyziologie MeSH
- proteiny buněčného cyklu metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- proteiny buněčného cyklu MeSH
The spindle assembly checkpoint (SAC) joins the machinery of chromosome-to-spindle microtubule attachment with that of the cell cycle to prevent missegregation of chromosomes during mitosis. Although a functioning SAC has been verified in a limited number of organisms, it is regarded as an evolutionarily conserved safeguard mechanism. In this report, we focus on the existence of the SAC in a single-celled parasitic eukaryote, Giardia intestinalis. Giardia belongs to Excavata, a large and diverse supergroup of unicellular eukaryotes in which SAC control has been nearly unexplored. We show that Giardia cells with absent or defective mitotic spindles due to the inhibitory effects of microtubule poisons do not arrest in mitosis; instead, they divide without any delay, enter the subsequent cell cycle and even reduplicate DNA before dying. We identified a limited repertoire of kinetochore and SAC components in the Giardia genome, indicating that this parasite is ill equipped to halt mitosis before the onset of anaphase via SAC control of chromosome-spindle microtubule attachment. Finally, based on overexpression, we show that Giardia Mad2, a core SAC protein in other eukaryotes, localizes along intracytoplasmic portions of caudal flagellar axonemes, but never within nuclei, even in mitotic cells with blocked spindles, where the SAC should be active. These findings are consistent with the absence of a conventional SAC, known from yeast and metazoans, in the parasitic protist Giardia.
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