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Mol. Cell. Biol., 09 1995, 5082-5091, Vol 15, No. 9
S Finnemann, M Kuhl, G Otto and D Wedlich
Cadherins are discussed not in terms of their adhesive function but rather
as morphoregulatory proteins. Changes in gene expression following cadherin
transfection of cells in culture or by overexpression in embryos have,
until now, not been reported. We established a protocol for stable
transfection of Xenopus XTC cells and generated cells bearing high levels
of membrane-integrated mouse uvomorulin (E-cadherin) or Xenopus
XB-cadherin. These cell lines showed drastically impaired substrate
adhesion on fibronectin and laminin. In immunoblot and
radioimmunoprecipitation experiments, we found that fibronectin and alpha
3/beta 1 integrin are downregulated. The reduced amounts of proteins result
from a decrease of the respective mRNAs as proven by RNase protection
assays. Coprecipitations revealed that transfected cadherin molecules are
complexed with alpha-catenin and beta-catenin at plasma membranes. However,
the alpha-catenin present in the XB-cadherin complex differs
immunologically from that found in the uvomorulin complex. When a truncated
form of XB-cadherin lacking 38 of the most C-terminal amino acids was
expressed in XTC cells, complex formation with endogenous catenins was
abolished. In these transfectants, substrate adhesion was not affected.
These results prove that complex formation of transfected cadherins in XTC
cells with endogenous beta-catenin correlates with altered synthesis of
certain substrate adhesion molecules.
Copyright © 1995, American Society for Microbiology
Cadherin transfection of Xenopus XTC cells downregulates expression of substrate adhesion molecules
Abteilung Biochemie, Universitat Ulm, Germany.
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