Direct interaction of tumor suppressor CEACAM1 with beta catenin: identification of key residues in the long cytoplasmic domain.
CEACAM1-4L (carcinoembryonic antigen cell adhesion molecule 1, with 4 extracellular Ig-like domains and a long, 71 amino acid cytoplasmic domain) is expressed in epithelial cells and activated T-cells, but is down-regulated in most epithelial cell cancers and T-cell leukemias. A highly conserved sequence within the cytoplasmic domain has ca 50% sequence homology with Tcf-3 and -4, transcription factors that bind beta-catenin, and to a lesser extent (32% homology), with E-cadherin that also binds beta-catenin. We show by quantitative yeast two-hybrid, BIAcore, GST-pull down, and confocal analyses that this domain directly interacts with beta-catenin, and that H-469 and K-470 are key residues that interact with the armadillo repeats of beta-catenin. Jurkat cells transfected with CEACAM1-4L have 2-fold less activity in the TOPFLASH reporter assay, and in MCF7 breast cancer cells that fail to express CEACAM1, transfection with CEACAM1 and growth in Ca2+ media causes redistribution of beta-catenin from the cytoplasm to the cell membrane, demonstrating a functional role for the long cytoplasmic domain of CEACAM1 in regulation of beta-catenin activity.
Jin
Lan
L
Division of Immunology, Beckman Research Institute of the City of Hope, 1450 E. Duarte Rd., Duarte, CA 91010, USA.
Li
Yun
Y
Chen
Charng-Jui
CJ
Sherman
Mark A
MA
Le
Keith
K
Shively
John E
JE
D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000032:analysis / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D019169:Jurkat Cells; D015458:Leukemia, T-Cell / Q000378:metabolism / Q000473:pathology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism* / Q000473:pathology; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D051176:beta Catenin / Q000032:analysis / Q000378:metabolism*
D015703:Antigens, CD; C069847:CD66 antigens; D015815:Cell Adhesion Molecules; D051176:beta Catenin