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© The Rockefeller University Press,
0021-9525/2001//465 $5.00
The Journal of Cell Biology, Volume 153, Number 3,
, 2001 465-478
Original Article |
Inhibitory Role of 
6β4-Associated Erbb-2 and Phosphoinositide 3-Kinase in Keratinocyte Haptotactic Migration Dependent on 3β1 Integrin
quaranta{at}scripps.edu
Keratinocytes and other epithelial cells express two receptors for the basement membrane (BM) extracellular matrix component laminin-5 (Ln-5), integrins
3β1 and 6β4. While 3β1 mediates adhesion, spreading, and migration (Kreidberg, J.A. 2000. Curr. Opin. Cell Biol. 12:548–553), 6β4 is involved in BM anchorage via hemidesmosomes (Borradori, L., and A. Sonnenberg. 1999. J. Invest. Dermatol. 112:411–418). We investigated a possible regulatory interplay between 3β1 and 6β4 in cell motility using HaCaT keratinocytes as a model. We found that 6β4 antibodies inhibit 3β1-mediated migration on Ln-5, but only when migration is haptotactic (i.e., spontaneous or stimulated by 3β1 activation), and not when chemotactic (i.e., triggered by epidermal growth factor receptor). Inhibition of migration by 6β4 depends upon phosphoinositide 3-kinase (PI3-K) since it is abolished by PI3-K blockers and by dominant-negative PI3-K, and constitutively active PI3-K prevents haptotaxis. In HaCaT cells incubated with anti–6β4 antibodies, activation of PI3-K is mediated by 6β4-associated erbB-2, as indicated by erbB-2 autophosphorylation and erbB-2/p85 PI3-K coprecipitation. Furthermore, dominant-negative erbB-2 abolishes inhibition of haptotaxis by anti–6β4 antibodies. These results support a model whereby (a) haptotactic cell migration on Ln-5 is regulated by concerted action of 3β1 and 6β4 integrins, (b) 6β4-associated erbB-2 and PI3-K negatively affect haptotaxis, and (c) chemotaxis on Ln-5 is not affected by 6β4 antibodies and may require PI3-K activity. This model could be of general relevance to motility of epithelial cells in contact with BM.
Key Words: erbB-2 • integrin • keratinocytes • laminin-5 • phosphoinositide 3-kinase
© 2001 The Rockefeller University Press
Abbreviations used in this paper: BM, basement membrane; ECM, extracellular matrix; ERK, extracellular signal-regulated kinase; FAK, focal adhesion kinase; Ln-5, laminin-5; MAP kinase, mitogen-activated protein kinase; ON, overnight; PI3-K, phosphoinositide 3-kinase; RT, room temperature.
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