Résumé
Objective To identify PDZ domain containing proteins interacting with PTEN and its characterization with NHERF-1 by proteomic analysis. Methods The interactions between PTEN and PDZ domain containing proteins were screened with PDZ protein array, and the novel one was then identified with GST pull-down and co-immunoprecipitation assay. Results Using a PDZ protein array, we proved PTEN binding with NHERF-1. The interaction of PTEN and NHERF-1 was further characterized by GST pull down assay, and we demonstrated that PTEN associated with NHERF-1 via the binding of PTEN carboxyl-terminal with the PDZ domain 1 (PDZ1) of NHERF-1. The last four amino acids (I-T-K-V) of the PTEN were the key determinants of this interaction as mutation of any of the four amino acids to alanine resulted in markedly reducing association of PTEN with NHERF-1. In addition, the full-length of PTEN robustly associated with NHERF-1 was also determined by co-immunoprecipitation experiment in cos-7 cells. Conclusion PTEN/NHERF-1 association was mediated via the binding of PTEN carboxyl-terminal]with the PDZ1 of NHERF-1, and the last four amino acids of the PTEN carboxyl-terminal were important for PTEN/NHERF-1 interaction.
Résumé
EBP50(ERM-binding phosphoprotein-50),a multifunctional adapter protein with 358 amino acids and two PDZ domains, regulates cell growth and migration. Lines of evidences indicate that it is a potential cancer suppressor protein. Loss of heterozygosity (LOH) and intragenic mutation of the ebp50 gene have been found in both primary breast tumors and breast cancer cell lines. EBP50 suppresses the breast cancer cell proliferation via its interaction with many tumor suppressor protein including PTEN, SYK, MERLIN, etc. Here the molecular structure of EBP50, signal pathway regulated by EBP50, and the relationship between breast cancer development and EBP50 are discussed.