Identification of proteins associating with glycosylphosphatidylinositol- anchored T-cadherin on the surface of vascular endothelial cells: Role for Grp78/BiP in T-cadherin-dependent cell survival

Maria Philippova, Danila Ivanov, Manjunath B. Joshi, Emmanouil Kyriakakis, Katharina Rupp, Taras Afonyushkin, Valery Bochkov, Paul Erne, Therese J. Resink

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There is scant knowledge regarding how cell surface lipid-anchored T-cadherin (T-cad) transmits signals through the plasma membrane to its intracellular targets. This study aimed to identify membrane proteins colocalizing with atypical glycosylphosphatidylinositol (GPI)-anchored T-cad on the surface of endothelial cells and to evaluate their role as signaling adaptors for T-cad. Application of coimmunoprecipitation from endothelial cells expressing c-myc-tagged T-cad and high-performance liquid chromatography revealed putative association of T-cad with the following proteins: glucose-related protein GRP78, GABA-A receptor α1 subunit, integrin β3, and two hypothetical proteins, LOC124245 and FLJ32070. Association of Grp78 and integrin β3 with T-cad on the cell surface was confirmed by surface biotinylation and reciprocal immunoprecipitation and by confocal microscopy. Use of anti-Grp78 blocking antibodies, Grp78 small interfering RNA, and coexpression of constitutively active Akt demonstrated an essential role for surface Grp78 in T-cad-dependent survival signal transduction via Akt in endothelial cells. The findings herein are relevant in the context of both the identification of transmembrane signaling partners for GPI-anchored T-cad as well as the demonstration of a novel mechanism whereby Grp78 can influence endothelial cell survival as a cell surface signaling receptor rather than an intracellular chaperone.

Original languageEnglish
Pages (from-to)4004-4017
Number of pages14
JournalMolecular and Cellular Biology
Issue number12
Publication statusPublished - 06-2008


All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Genetics
  • Cell Biology

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