scholarly journals Expansion microsopy reveals Plasmodium falciparum blood-stage parasites undergo anaphase with a chromatin bridge in the absence of mini-chromosome maintenance complex binding protein

2021 ◽  
Author(s):  
Benjamin Liffner ◽  
Sabrina Absalon
Keyword(s):  
Plasmodium Falciparum ◽  
Nuclear Envelope ◽  
Malaria Parasite ◽  
Binding Protein ◽  
Nuclear Morphology ◽  
Mitotic Spindles ◽  
Human Host ◽  
The Individual ◽  
Chromatin Bridges

ABSTRACTMitosis in the malaria parasite Plasmodium falciparum undergoes closed mitosis, which occurs within an intact nuclear envelope, and differs significantly from its human host. Mitosis is underpinned by the dynamics of microtubules and the nuclear envelope. To date, our ability to study P. falciparum mitosis by microscopy has been hindered by the small size of P. falciparum nuclei. Ultrastructure expansion microscopy (U-ExM) has recently been developed for P. falciparum, allowing visualization of mitosis at the individual nucleus level. Using U-ExM, three intranuclear microtubule structures are observed: hemispindles, mitotic spindles and interpolar spindles. A previous study demonstrated that the mini-chromosome maintenance complex binding-protein (MCMBP) depletion caused abnormal nuclear morphology and microtubule defects. To investigate the role of microtubules following MCMBP depletion and study the nuclear envelope in these parasites, we developed the first nuclear stain enabled by U-ExM in P. falciparum. MCMBP deficient parasites show aberrant hemispindles and mitotic spindles. Moreover, anaphase chromatin bridges, and individual nuclei containing multiple microtubule structures were observed following MCMBP knockdown. Collectively, this study refines our model for the phenotype of MCMBP-deficient parasites and highlights the utility of U-ExM coupled with a nuclear envelope stain for studying mitosis in P. falciparum.

scholarly journals Expansion Microscopy Reveals Plasmodium falciparum Blood-Stage Parasites Undergo Anaphase with A Chromatin Bridge in the Absence of Mini-Chromosome Maintenance Complex Binding Protein

2021 ◽  
Vol 9 (11) ◽  
pp. 2306
Author(s):  
Benjamin Liffner ◽  
Sabrina Absalon
Keyword(s):  
Plasmodium Falciparum ◽  
Nuclear Envelope ◽  
Malaria Parasite ◽  
Binding Protein ◽  
Mitotic Spindles ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
The Individual ◽  
Chromatin Bridges

The malaria parasite Plasmodium falciparum undergoes closed mitosis, which occurs within an intact nuclear envelope, and differs significantly from its human host. Mitosis is underpinned by the dynamics of microtubules and the nuclear envelope. To date, our ability to study P. falciparum mitosis by microscopy has been hindered by the small size of the P. falciparum nuclei. Ultrastructure expansion microscopy (U-ExM) has recently been developed for P. falciparum, allowing the visualization of mitosis at the individual nucleus level. Using U-ExM, three intranuclear microtubule structures are observed: hemispindles, mitotic spindles, and interpolar spindles. A previous study demonstrated that the mini-chromosome maintenance complex binding-protein (MCMBP) depletion caused abnormal nuclear morphology and microtubule defects. To investigate the role of microtubules following MCMBP depletion and study the nuclear envelope in these parasites, we developed the first nuclear stain enabled by U-ExM in P. falciparum. MCMBP-deficient parasites show aberrant hemispindles and mitotic spindles. Moreover, anaphase chromatin bridges and individual nuclei containing multiple microtubule structures were observed following MCMBP knockdown. Collectively, this study refines our understanding of MCMBP-deficient parasites and highlights the utility of U-ExM coupled with a nuclear envelope stain for studying mitosis in P. falciparum.

scholarly journals SUN proteins facilitate the removal of membranes from chromatin during nuclear envelope breakdown

2014 ◽  
Vol 204 (7) ◽  
pp. 1099-1109 ◽  
Author(s):  
Yagmur Turgay ◽  
Lysie Champion ◽  
Csaba Balazs ◽  
Michael Held ◽  
Alberto Toso ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Dominant Negative ◽  
Mitotic Spindles ◽  
Mitotic Progression ◽  
Microtubule Depolymerization ◽  
Nuclear Envelope Breakdown ◽  
And Migration ◽  
Delayed Removal

SUN proteins reside in the inner nuclear membrane and form complexes with KASH proteins of the outer nuclear membrane that connect the nuclear envelope (NE) to the cytoskeleton. These complexes have well-established functions in nuclear anchorage and migration in interphase, but little is known about their involvement in mitotic processes. Our analysis demonstrates that simultaneous depletion of human SUN1 and SUN2 delayed removal of membranes from chromatin during NE breakdown (NEBD) and impaired the formation of prophase NE invaginations (PNEIs), similar to microtubule depolymerization or down-regulation of the dynein cofactors NudE/EL. In addition, overexpression of dominant-negative SUN and KASH constructs reduced the occurrence of PNEI, indicating a requirement for functional SUN–KASH complexes in NE remodeling. Codepletion of SUN1/2 slowed cell proliferation and resulted in an accumulation of morphologically defective and disoriented mitotic spindles. Quantification of mitotic timing revealed a delay between NEBD and chromatin separation, indicating a role of SUN proteins in bipolar spindle assembly and mitotic progression.

scholarly journals Genetic alteration of ferredoxin NADP+-reductase or cysteine desulfurase in piperaquine-resistant Plasmodium berghei restores susceptibility to lumefantrine and abolishes the impact of probenecid, verapamil, and cyproheptadine

2019 ◽  
Author(s):  
Fagdéba David Bara ◽  
Loise Ndung’u ◽  
Noah Machuki Onchieku ◽  
Beatrice Irungu ◽  
Simplice Damintoti Karou ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Berghei ◽  
Malaria Parasite ◽  
Drug Action ◽  
Cysteine Desulfurase ◽  
Human Malaria Parasite ◽  
Human Malaria ◽  
Essential Components ◽  
The Impact

AbstractChemotherapy remains central in the control of malaria; however, resistance has consistently thwarted these efforts. Currently, lumefantrine (LM), and piperaquine (PQ) drugs, are essential components in the mainstay artemisinin-based therapies used for the treatment of malaria globally. Using LM and PQ-resistant Plasmodium berghei, we measured the effect of known chemosensitizers: probenecid, verapamil, or cyproheptadine on the activity of LM or PQ. Using PlasmoGEM vectors, we then evaluated the impact of deleting cysteine desulfurase (SufS) or over-expressing Ferredoxin NADP+ reductase (FNR), genes that mediate drug action. Our data showed that, only cyproheptadine at 5mgkg−1 restored LM activity by above 65% against the LM-resistant parasites (LMR) but failed to reinstate PQ activity against the PQ-resistant parasites (PQR). Whereas the PQR had lost significant susceptibility to LM, the three chemosensitizers; cyproheptadine, probenecid, and verapamil, restored LM potency against the PQR by above 70%, 60%, and 55% respectively. We thus focused on LM resistance in PQR. Deletion of the SufS or overexpression of the FNR genes in the PQR abolished the impact of the chemosensitizers on the LM activity, and restored the susceptibility of the PQR parasites to LM. Taken together, we demonstrate the association between SufS or FNR genes with the action of LM and chemosensitizers in PQR parasites. There is, however, need to interrogate the impact of the chemosensitizers and the role of SufS or FNR genes on LM action in the human malaria parasite, Plasmodium falciparum.

scholarly journals Role of Known Molecular Markers of Resistance in the Antimalarial Potency of Piperaquine and Dihydroartemisinin In Vitro

2009 ◽  
Vol 53 (4) ◽  
pp. 1362-1366 ◽  
Author(s):  
Sant Muangnoicharoen ◽  
David J. Johnson ◽  
Sornchai Looareesuwan ◽  
Srivicha Krudsood ◽  
Stephen A. Ward
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Artemisinin Combination Therapy ◽  
Parasite Line ◽  
South American ◽  
Resistance Markers ◽  
Positive Correlations ◽  
The Individual

ABSTRACT Using a range of laboratory-adapted and genetically modified Plasmodium falciparum parasite isolates, we investigated the interaction between dihydroartemisinin and piperaquine (PIP), the individual components of an artemisinin combination therapy currently under development, in addition to the role of known drug resistance genes in parasite susceptibility in vitro. All but one parasite line investigated displayed an interaction of dihydroartemisinin and PIP that was antagonistic, although the degree of antagonism was isolate dependent. In terms of resistance markers, the pfcrt haplotypes CVIET and SVMNT were positively associated with reduced sensitivity to PIP, with parasites carrying the South American CQR (SVMNT) allele being generally less sensitive than CVIET parasites. Parasites carrying the CQS (CVMNK) allele displayed a further increase in PIP sensitivity compared with CVIET and SVMNT parasites. Our data indicate that PIP sensitivity was not affected by pfmdr1 sequence status, despite positive correlations between the structurally related compound amodiaquine and pfmdr1 mutations in other studies. In contrast, neither the pfcrt nor pfmdr1 sequence status had any significant impact on susceptibility to dihydroartemisinin.

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