Ablation of the single dynamin of <i>T. brucei</i> blocks mitochondrial fission and endocytosis and leads to a precise cytokinesis arrest

Chanez, Anne-Laure; Hehl, Adrian B.; Engstler, Markus; Schneider, André

doi:10.1242/jcs.03023

Cited by 84 publications

(109 citation statements)

References 40 publications

(62 reference statements)

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“…The GTPase dynamin was shown to be essential for division of mitochondria in eukaryotic cells (Legesse-Miller et al, 2003;Shpetner and Vallee, 1989), and knockdown of the single dynamin-like protein in T. brucei regulates mitochondrial division (Morgan et al, 2004). Further work showed that knockdown led to a precise cell cycle arrest with an accumulation of cells that were still connected at their posterior ends only (Chanez et al, 2006) and thus, were highly similar to the stage 8 cells outlined in this work. We did not observe any fragmentation of the mitochondrion, but branching was observed via expansion into flattened areas and appearance of fenestrations.…”

Section: Discussionsupporting

confidence: 64%

Patterns of organelle ontogeny through a cell cycle revealed by whole-cell reconstructions using 3D electron microscopy

Hughes

Borrett

Towers

et al. 2017

Journal of Cell Science

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The major mammalian bloodstream form of the African sleeping sickness parasite Trypanosoma brucei multiplies rapidly, and it is important to understand how these cells divide. Organelle inheritance involves complex spatiotemporal re-arrangements to ensure correct distribution to daughter cells. Here, serial block face scanning electron microscopy (SBF-SEM) was used to reconstruct whole individual cells at different stages of the cell cycle to give an unprecedented temporal, spatial and quantitative view of organelle division, inheritance and abscission in a eukaryotic cell. Extensive mitochondrial branching occurred only along the ventral surface of the parasite, but the mitochondria returned to a tubular form during cytokinesis. Fission of the mitochondrion occurred within the cytoplasmic bridge during the final stage of cell division, correlating with cell abscission. The nuclei were located underneath each flagellum at mitosis and the mitotic spindle was located along the ventral surface, further demonstrating the asymmetric arrangement of cell cleavage in trypanosomes. Finally, measurements demonstrated that multiple Golgi bodies were accurately positioned along the flagellum attachment zone, suggesting a mechanism for determining the location of Golgi bodies along each flagellum during the cell cycle.

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Section: Discussionsupporting

confidence: 64%

Patterns of organelle ontogeny through a cell cycle revealed by whole-cell reconstructions using 3D electron microscopy

Hughes

Borrett

Towers

et al. 2017

Journal of Cell Science

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“…One possible explanation for this effect could be that the inability of the kinetoplast DNA to replicate or segregate activates a cell-cycle checkpoint, which results in a cell-cycle block. In a recent report, the ablation of the single DYNAMIN gene in T. brucei by RNAi, resulted in the inhibition of the kDNA segregation and, as a consequence, in cell cycle arrest and a disturbance of the cytokinesis process (29). We suggest the existence of a checkpoint, which could be activated when either minicircle replication does not initiate properly or kinetoplast DNA segregation is compromised.…”

Section: Discussionmentioning

confidence: 61%

Mitochondrial origin-binding protein UMSBP mediates DNA replication and segregation in trypanosomes

Milman

Motyka

Englund

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Kinetoplast DNA (kDNA) is the remarkable mitochondrial genome of trypanosomatids. Its major components are several thousands of topologically linked DNA minicircles, whose replication origins are bound by the universal minicircle sequence-binding protein (UMSBP). The cellular function of UMSBP has been studied in Trypanosoma brucei by using RNAi analysis. Silencing of the trypanosomal UMSBP genes resulted in remarkable effects on the trypanosome cell cycle. It significantly inhibited the initiation of minicircle replication, blocked nuclear DNA division, and impaired the segregation of the kDNA network and the flagellar basal body, resulting in growth arrest. These observations, revealing the function of UMSBP in kDNA replication initiation and segregation as well as in mitochondrial and nuclear division, imply a potential role for UMSBP in linking kDNA replication and segregation to the nuclear S-phase control during the trypanosome cell cycle.kDNA replication initiation ͉ kDNA segregation ͉ kinetoplast DNA ͉ trypanosomes cell cycle control ͉ universal minicircle sequence-binding protein K inetoplast DNA (kDNA) is a unique extrachromosomal DNA, found in the single mitochondrion of trypanosomatids. It consists, in the different species, of a few dozen maxicircles (20-40 kb each) and a few thousand minicircles (0.5-10 kb each), that are interlocked topologically into a DNA network (1, 2). Minicircles in most trypanosomatid species contain two short sequences that are associated with replication initiation: a dodecamer, designated the universal minicircle sequence (UMS), and a hexamer. These sequences have been mapped to the replication origins of the minicircle's light (L) and heavy (H) strands, respectively. kDNA replication occurs during S phase of the cell cycle, approximately in parallel with nuclear DNA replication (3). Minicircles are released from the network into the kinetoflagellar zone, located in the mitochondrial matrix, between the kDNA network and the flagellar basal body. Each minicircle replicates as an individual replicon, forming gapped and nicked progeny molecules. Minicircle replication intermediates then migrate onto two antipodal sites, flanking the kDNA disk, in which primer-removal, repair of the gaps between Okazaki fragments and reattachment of the progeny minicircles to the network occurs. The final gap-filling and sealing of the topologically linked minicircles take place before the network division (recently reviewed in refs. 1 and 2).We have previously reported the presence in Crithidia fasciculata of a UMS-binding protein (UMSBP). The protein, which contains five tandemly arranged CCHC-type zinc-finger motifs, has been purified from cell extracts, and its encoding gene and genomic locus were cloned and analyzed (4-7). Genes encoding orthologous proteins have been identified in other trypanosomatid species [ref. 8 and supporting information (SI) Table 1]. UMSBP binds specifically the two conserved sequences, located at the minicircle replication origins: the UMS dodecamer and an H-st...

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“…250 nm. Is Plasmodium dynamin-2 involved in the division of both the mitochondrion and apicoplast, akin to the use of only one dynamin by Trypanosoma brucei for mitochondrial fission and endocytosis (Chanez et al, 2006)? If so, how is dynamin-mediated fission of these organelles controlled, when at least in erythrocytic stages, division of the mitochondrion and apicoplast do not occur synchronously?…”

Section: Examination Of the Apicoplast Throughout The P Berghei Lifementioning

confidence: 99%

GFP‐targeting allows visualization of the apicoplast throughout the life cycle of live malaria parasites

Stanway

Witt

Zobiak

et al. 2009

Biology of the Cell

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Background information. The Plasmodium parasite, during its life cycle, undergoes three phases of asexual reproduction, these being repeated rounds of erythrocytic schizogony, sporogony within oocysts on the mosquito midgut wall and exo-erythrocytic schizogony within the hepatocyte. During each phase of asexual reproduction, the parasite must ensure that every new daughter cell contains an apicoplast, as this organelle cannot be formed de novo and is essential for parasite survival. To date, studies visualizing the apicoplast in live Plasmodium parasites have been restricted to the blood stages of Plasmodium falciparum.Results. In the present study, we have generated Plasmodium berghei parasites in which GFP (green fluorescent protein) is targeted to the apicoplast using the specific targeting sequence of ACP (acyl carrier protein), which has allowed us to visualize this organelle in live Plasmodium parasites. During each phase of asexual reproduction, the apicoplast becomes highly branched, but remains as a single organelle until the completion of nuclear division, whereupon it divides and is rapidly segregated into newly forming daughter cells. We have shown that the antimicrobial agents azithromycin, clindamycin and doxycycline block development of the apicoplast during exo-erythrocytic schizogony in vitro, leading to impaired parasite maturation.Conclusions. Using a range of powerful live microscopy techniques, we show for the first time the development of a Plasmodium organelle through the entire life cycle of the parasite. Evidence is provided that interference with the development of the Plasmodium apicoplast results in the failure to produce red-blood-cell-infective merozoites.

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Ablation of the single dynamin of T. brucei blocks mitochondrial fission and endocytosis and leads to a precise cytokinesis arrest

Abstract: SummaryAblation of the single dynamin of T. brucei blocks mitochondrial fission and endocytosis and leads to a precise cytokinesis arrest

Cited by 84 publications

References 40 publications

Patterns of organelle ontogeny through a cell cycle revealed by whole-cell reconstructions using 3D electron microscopy

Patterns of organelle ontogeny through a cell cycle revealed by whole-cell reconstructions using 3D electron microscopy

Mitochondrial origin-binding protein UMSBP mediates DNA replication and segregation in trypanosomes

GFP‐targeting allows visualization of the apicoplast throughout the life cycle of live malaria parasites

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