Cell Biology

Just Being Neighborly

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Science  21 Dec 2001:
Vol. 294, Issue 5551, pp. 2431
DOI: 10.1126/science.294.5551.2431d

In tissues and organs, epithelial cells form tight barriers that demarcate extracellular compartments. On occasion, one of these cells may undergo apoptosis (programmed cell death). Clearance of apoptotic cells by phagocytosis is known to occur elsewhere, but in an epithelium this process might create a hole or promote leakage with deleterious consequences.

Rosenblatt et al. describe how an epithelium actively evicts dying cells. When a cell enters the apoptotic pathway, its neighbors construct and contract an encircling network of actin and myosin. It appears that apoptotic cells directly signal their neighbors to expel them; indeed, an apoptotic cell simply placed on top of an epithelial layer also stimulates the formation of these actin cables. Precisely how the contraction of the surrounding cells is orchestrated to retain epithelial integrity is not yet clear, but even when multiple cells simultaneously undergo apoptosis, electrical integrity of the epithelial barrier is maintained.—SMH

Curr. Biol.11, 1847 (2001).

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