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.
Highlights
Cytokinesis is the final stage of cell division in which one parent cell is physically divided into two daughter cells
Representative images of five stages of mitosis from metaphase to late cytokinesis are shown in Figure 1A and the complete time-series can be viewed in Movie S1
As the cleavage furrow formed in early cytokinesis, the mitochondria were further enriched at the furrow and reduced at the cell poles
Summary
Cytokinesis is the final stage of cell division in which one parent cell is physically divided into two daughter cells. Astral and spindle microtubules specify the assembly of an actomyosin contractile ring at the equator of the cell between separating chromosomes [1,2,3,4,5,6,7]. This ensures that daughter cells inherit a proper complement of genetic and cytoplasmic material. A multitude of cellular and molecular processes take place at the furrow in order for cytokinesis to proceed, including actin polymerization, actomyosin contraction, signaling events, motor activity and membrane trafficking and fusion [8]
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