Cell Biology

Squeezed Out by the Neighbors

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Science  02 Oct 2009:
Vol. 326, Issue 5949, pp. 21
DOI: 10.1126/science.326_21a
CREDIT: SLATTUM ET AL., J. CELL BIOL. 186, 693 (2009)

Organs and tissues are surrounded by an epithelial layer of cells that serves as a physical barrier between, for instance, the blood and the vascular smooth muscle cells. If and when cells within an epithelial layer die, they must be removed without breaching the integrity of the epithelial barrier. Slattum et al. have characterized the process by which apoptotic cells are actively extruded. There is a localized contraction of actin and myosin IIA within the cells (blue) that surround the dying cell—at their apical ends if the target cell is destined to exit into the tissue or, more commonly, at their basolateral surfaces if the cell is to be extruded into the luminal compartment. The latter requires microtubules (green) in the neighboring cells to reorient and to target a protein that controls actin and myosin activity, p115 RhoGEF, to the basolateral surface. In the whole organism, the direction of extrusion may figure in the subsequent fate of the ejected cell, particularly if, as may happen during tumorigenesis, the presumptive apoptotic cell does not in fact die.

J. Cell Biol. 186, 693 (2009).

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