A new job for ancient extracellular matrix proteins

Abstract

Interactions between extracellular matrix (ECM) proteins and transmembrane receptors mediate changes in cell shape during cell migration, adhesion, differentiation and polarization. Cytokinesis is the final step in cell division as cells employ a contractile ring composed of actin and myosin to partition one cell into two. During the partition process, an invagination in nascent membrane forms a new extracellular space called the cleavage furrow. Despite the dramatic changes in cell shape during cytokinesis, existing models include no role for the ECM. In a recent paper, we show that hemicentins assemble in the cleavage furrow of C. elegans germ cells and mouse embryo blastomeres. Hemicentin depletion results in membrane destabilization, cleavage furrow retraction and cytokinesis failure. The data suggest that hemicentins and other ECM proteins stabilize the cleavage furrow during cytokinesis of multiple cell types.

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Acknowledgments

This work was supported by funding from the National Science Foundation (MCB0744838) and the National Institutes of Health (GM65184).

Figures and Tables

Figure 1 Hemicentins assemble in the cleavage furrow. Schematic diagram of hemicentin (green) in the incomplete cleavage furrow of a conventional cell (e.g., mouse blastomere, top) and a syncytial germ cell of the C. elegans gonad (bottom). An expanded view (box 1) shows a simple model in which hemicentin (green) assembles as an elastic ring around the periphery of the cleavage furrow leading edge. An unconventional model (box 2) shows hemicentin in a distal position from the leading edge of the cleavage furrow. Hemicentin polymers may be assembled perpendicular to the membrane, linking the two cellular products of cytokinesis, a distribution that is more consistent with the role of hemicentins as elastic connectors between somatic cells in C. elegans. Also shown are nuclei (black circles) contractile rings (red circles) and putative transmembrane receptors (brown lines).

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