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How polarized epithelial cells maintain their unique asymmetry

From eggs to adults, the establishment and maintenance of asymmetry is essential for life. Throughout biology, this asymmetry results in polarized cells, tissues and organs that require asymmetry to function correctly. For many years, biologists have studied the processes that contribute to cell polarity. These include receiving and responding to external signals, the re-organization of the cytoskeleton and the directional transport of molecules to specific sites at the cell surface. When these processes go awry, polarity is disrupted. In humans, this can result in a variety of disease states of varying severity.

Researchers at the MPI-CBG in collaboration with the Hoflack lab at the Technische Universität Dresden have recently reported on one of the processes required to maintain epithelial cell polarity. With the aid of a technique newly developed in the Hoflack lab, they identified a mechanism essential for maintaining the levels and localization of a key polarity determinant, Crumbs. They found that the transport of Crumbs by the retromer trafficking machinery prevents Crumbs entering a default degradation pathway. In the absence of retromer, the ensuing loss of Crumbs leads to the loss of polarity and finally the loss of tissue integrity. These findings reveal a new route by which polarized epithelial cells maintain their unique asymmetry.

original publication:
Pocha SM, Wassmer T, Niehage C, Hoflack B, Knust E:
Retromer controls epithelial cell polarity by trafficking the apical determinant Crumbs.
Curr Biol. 2011 Jul 12;21(13):1111-7. Epub 2011 Jun 23.