Truncated E-cadherin potentiates cell death in prostate epithelial cells.
BACKGROUND
E-cadherin, a fundamental component of the adherens junction, is known to mediate aggregation-dependent cell survival. We have previously identified a novel, calpain-dependent proteolytic cleavage of E-cadherin that resulted in the generation of a stable 100-kDa E-cadherin fragment (E-cad(100)) in prostate epithelial cells in response to cell death stimuli. We postulated that the E-cad(100) fragment may play a role in abrogating survival of LNCaP cells following induction of apoptosis.


METHODS
Wild-type E-cadherin and E-cad(100) were engineered, tagged with GFP, and stably expressed in LNCaP cells. These cell lines were characterized for E-cadherin-GFP/beta-catenin interactions, endogenous E-cadherin and beta-catenin expression, and sensitivity to apoptosis induced by PKC activation.


RESULTS
E-cad(100)-GFP demonstrated a punctuate expression pattern, in contrast to E-cad(120)-GFP, which was membrane-localized. E-cad(100)-GFP, unlike E-cad(120)-GFP, failed to bind to and co-localize with beta-catenin. Transient or stable overexpression of E-cad(100) resulted in the downregulation of endogenous E-cadherin expression at the cell membrane. Activation of PKC in LNCaP cells which overexpressed E-cad(100) potentiated cell death.


CONCLUSIONS
Truncated E-cadherin may play a role in the regulation of endogenous E-cadherin expression and epithelial cell survival.
Rios-Doria
Jonathan
J
Department of Urology, University of Michigan, Ann Arbor, Michigan, USA.
Day
Mark L
ML
D000595:Amino Acid Sequence; D017209:Apoptosis / Q000187:drug effects*; D015820:Cadherins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002154:Calpain / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D003598:Cytoskeletal Proteins / Q000235:genetics; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000737:chemistry / Q000166:cytology*; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics / Q000502:physiology*; D011467:Prostate / Q000166:cytology*; D011493:Protein Kinase C / Q000378:metabolism; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators / Q000235:genetics; D014162:Transfection; D051176:beta Catenin
C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D051176:beta Catenin; D049452:Green Fluorescent Proteins; D011493:Protein Kinase C; D002154:Calpain