Figure 2

Subcelluar localization and protein structure of E-cadherin. Two different E-cadherin antibodies were used to localize E-cadherin in tumors. An E-cadherin extracellular domain-based immunogen showed loss or reduced E-cadherin expression, whereas the same tumors showed increased nuclear accumulation of E-cadherin when an E-cadherin antibody raised against the intracellular domain was used (a). These results indicate that extracellular part of E-cadherin is lost in tumors, whereas the C-terminal domain is released into the cytoplasm and accumulates in the nucleus. The two constructs used in this study expressed aa 725–882 (Ecad-2301) and aa 594–882 (Ecad-1904), the latter of which, in addition to intracellular domains of E-cadherin, also contains one extracellular domain and the transmembrane domain (a). To examine whether the cytoplasmic domains of E-cadherin can translocate to the nucleus, HEK293 cells were transfected with either Ecad-2301 or Ecad-1904 constructs (b). Cell extracts were fractionated and cytoplasmic and nuclear lysates were resolved by western blot analysis using an E-cadherin antibody raised against the cytoplasmic tail of the protein. Ecad-1904 clearly translocated to the nucleus, whereas Ecad-2301 was efficiently cleaved and was found predominantly in the cytosol. Both E-cadherin recombinant proteins (Ecad-2301 and Ecad-1904) undergo cleavage (b).