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A more recent version of this article appeared on January 1, 2009
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Submitted on April 6, 2008
Revised on October 1, 2008
Accepted on October 29, 2008
Departments of Pathology and Dermatology, and the R.H. Lurie Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
Monitoring Editor: Asma Nusrat
Regulation of classic cadherins plays a critical role in tissue remodeling during development and cancer; however, less attention has been paid to the importance of desmosomal cadherins. We previously showed that EGFR inhibition results in accumulation of the desmosomal cadherin, desmoglein 2 (Dsg2), at cell-cell interfaces accompanied by inhibition of matrix metalloprotease (MMP)-dependent shedding of the Dsg2 ectodomain and tyrosine phosphorylation of its cytoplasmic domain. Here, we show that EGFR inhibition stabilizes Dsg2 at intercellular junctions by interfering with its accumulation in an internalized cytoplasmic pool. Furthermore, MMP inhibition and ADAM17 RNAi, blocked shedding and depleted internalized Dsg2, but less so E-cadherin, in highly invasive SCC68 cells. ADAM9 and 15 silencing also impaired Dsg2 processing, supporting the idea that this desmosomal cadherin can be regulated by multiple ADAM family members. In contrast, ADAM10 siRNA enhanced accumulation of a 100 kDa Dsg2 cleavage product and internalized pool of Dsg2. While both MMP and EGFR inhibition increased intercellular adhesive strength in control cells, the response to MMP-inhibition was Dsg2-dependent. These data support a role for endocytic trafficking in regulating desmosomal cadherin turnover and function, and raise the possibility that internalization and regulation of desmosomal and classic cadherin function can be uncoupled mechanistically.
Present adress: Departments of Dermatology, Cell and Molecular Biology, and the R.H. Lurie Cancer Center.
Address correspondence to:
Kathleen J. Green (kgreen{at}northwestern.edu)