Polarity sets the stage for cytokinesis

Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Molecular biology of the cell (Impact Factor: 4.47). 01/2012; 23(1):7-11. DOI: 10.1091/mbc.E11-06-0512
Source: PubMed


Cell polarity is important for a number of processes, from chemotaxis to embryogenesis. Recent studies suggest a new role for polarity in the orchestration of events during the final cell separation step of cell division called abscission. Abscission shares several features with cell polarization, including rearrangement of phosphatidylinositols, reorganization of microtubules, and trafficking of exocyst-associated membranes. Here we focus on how the canonical pathways for cell polarization and cell migration may play a role in spatiotemporal membrane trafficking events required for the final stages of cytokinesis.

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    • "Recently, it has been shown that mitochondria accumulate around the nucleus in arterial endothelial cells under hypoxic conditions, leading to an increase of ROS in the nucleus and induction of transcription [69]. During cytokinesis, the cell becomes highly polarized [70] and may, therefore, have specific energetic and metabolic requirements that would necessitate the local enrichment of mitochondria at the cleavage furrow. For example, ATP produced by mitochondria is required for the assembly and contraction of the cytokinetic ring [71]–[74] and is utilized by kinases at the cleavage furrow and kinesin motors in the spindle [74]–[79]. "
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    ABSTRACT: Mitochondria are dynamic organelles with multiple cellular functions, including ATP production, calcium buffering, and lipid biosynthesis. Several studies have shown that mitochondrial positioning is regulated by the cytoskeleton during cell division in several eukaryotic systems. However, the distribution of mitochondria during mammalian cytokinesis and whether the distribution is regulated by the cytoskeleton has not been examined. Using live spinning disk confocal microscopy and quantitative analysis of mitochondrial fluorescence intensity, we demonstrate that mitochondria are recruited to the cleavage furrow during cytokinesis in HeLa cells. After anaphase onset, the mitochondria are recruited towards the site of cleavage furrow formation, where they remain enriched as the furrow ingresses and until cytokinesis completion. Furthermore, we show that recruitment of mitochondria to the furrow occurs in multiple mammalian cells lines as well as in monopolar, bipolar, and multipolar divisions, suggesting that the mechanism of recruitment is conserved and robust. Using inhibitors of cytoskeleton dynamics, we show that the microtubule cytoskeleton, but not actin, is required to transport mitochondria to the cleavage furrow. Thus, mitochondria are specifically recruited to the cleavage furrow in a microtubule-dependent manner during mammalian cytokinesis. Two possible reasons for this could be to localize mitochondrial function to the furrow to facilitate cytokinesis and / or ensure accurate mitochondrial inheritance.
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    ABSTRACT: During the final stage of cell division, the future daughter cells are physically separated through abscission. This process requires coordination of many molecular machines, including endocytic and secretory vesicle trafficking proteins as well as ESCRT (endosomal sorting complex required for transport) proteins, that mediate a complex series of events to culminate in the final separation of daughter cells. Abscission is coordinated with other cellular processes (for example, nuclear pore reassembly) through mitotic kinases such as Aurora B and Polo-like kinase 1, which act as master regulators to ensure proper progression of abscission.
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