Damage Detection

Science's STKE  25 Mar 2003:
Vol. 2003, Issue 175, pp. tw114-TW114
DOI: 10.1126/stke.2003.175.tw114

Protein complexes called tight junctions hold adjacent cells of an epithelial monolayer tightly together, creating a physical barrier between apical and basolateral membranes. Vermeer et al. show that in human airway epithelia, tight junctions keep the growth factor heregulin, and its receptor, erbB2, apically and basolaterally localized, respectively. Why this distinct localization? The authors suggest that this may be a strategy for a polarized epithelium to sense tissue damage. When tight junction integrity of an epithelial monolayer was disrupted, either by mechanical damage or by chelation of extracellular calcium, erbB2 became activated through access to heregulin. Heregulin is normally cleaved from the outer surface of the apical plasma membrane and is found in fluid that coats the airways. The authors propose that this mechanism could initiate cell proliferation and other processes to heal damaged tissue.

P. D. Vermeer, L. A. Einwalter, T. O. Moninger, T. Rokhlina, J. A. Kern, J. Zabner, M. J. Welsh, Segregation of receptor and ligand regulates activation of epithelial growth factor receptor. Nature 422, 322-326 (2003). [Online Journal]