Alternate histories of cytokinesis: lessons from the trypanosomatids

Abstract

Popular culture has recently produced several “alternate histories” that describe worlds where key historical events had different outcomes. Beyond entertainment, asking “could this have happened a different way?” and “what would the consequences be?” are valuable approaches for exploring molecular mechanisms in many areas of research, including cell biology. Analogous to alternate histories, studying how the evolutionary trajectories of related organisms have been selected to provide a range of outcomes can tell us about the plasticity and potential contained within the genome of the ancestral cell. Among eukaryotes, a group of model organisms has been employed with great success to identify a core, conserved framework of proteins that segregate the duplicated cellular organelles into two daughter cells during cell division, a process known as cytokinesis. However, these organisms provide relatively sparse sampling across the broad evolutionary distances that exist, which has limited our understanding of the true potential of the ancestral eukaryotic toolkit. Recent work on the trypanosomatids, a group of eukaryotic parasites, exemplifies alternate historical routes for cytokinesis that illustrate the range of eukaryotic diversity, especially among unicellular organisms.

Kinetoplastid-specific X2-family kinesins interact with a kinesin-like pleckstrin homology domain protein that localizes to the trypanosomal microtubule quartet

“…First, most of the proteins identified in our study were also observed in the TOEFAZ1/CIF1 proxisome with high confidence (28). This verifies our localization of TbKifX2/TbPH1 along the whole length of the MtQ and not just the proximal end, since TOEFAZ1/CIF1 is enriched in the distal tip of a newly formed FAZ, which also incorporates a new MtQ (8,58). Second, the TbPH1 proxisome contains DLP1/2, which are involved in clathrin-mediated endocytosis (41-43) and FP45, which surrounds the flagellar pocket where endocytosis takes place.…”

Actin-based myosin XXI (13) molecular motor is involved in early phase ofLeishmaniacytokinesis

“…In Trypanosoma, the mechanisms and proteins involved in cytokinesis are relatively well studied [9,26]. However, in Leishmania, only a few proteins, which are involved in cytokinesis, have been identified, but mechanistic details are still obscure.…”

Cell Cycle, Telomeres, and Telomerase in Leishmania spp.: What Do We Know So Far?

“…During the M phase, Leishmania spp. and all other trypanosomatids do not disassemble their nuclear envelope and perform a closed mitosis process, which is organized by spindle pole body-like structures [52]. Moreover, due to the absence of the N-terminal portion and globular domain of histone H1 and the absence of phosphorylation on serine 10 of histone H3 (H3S10), Leishmania spp.…”

“…Once mitosis ends, Leishmania spp. undergo a rapid remodeling in shape, first growing in length and then in width prior to cytokinesis, which ends cell division [52,55]. Although it is challenging, all these peculiarities related to the cell cycle phases may provide new routes toward the search for suitable targets for parasite cell cycle interventions aiming at their elimination.…”