July 1, 2007 Journal article Closed Access

André Nantel; André Nantel; Colin L. Stewart; Maria Huber; Matthew G. Annis; John P. Hagan; Josée Ash; Malcolm Whiteway; Malcolm Whiteway; Sem Kebache; Jennifer Hassard

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{
  "DOI": "10.1074/jbc.m611066200", 
  "abstract": "The proapoptotic protein Bad is a key player in cell survival decisions, and is regulated post-translationally by several signaling networks. We expressed Bad in mouse embryonic fibroblasts to sensitize them to apoptosis, and tested cell lines derived from knock-out mice to establish the significance of the interaction between the adaptor protein Grb10 and the Raf-1 protein kinase in anti-apoptotic signaling pathways targeting Bad. When compared with wild-type cells, both Grb10 and Raf-1-deficient cells exhibit greatly enhanced sensitivity to apoptosis in response to Bad expression. Structure-function analysis demonstrates that, in this cellular model, the SH2, proline-rich, and pleckstrin homology domains of Grb10, as well as its Akt phosphorylation site and consequent binding by 14-3-3, are all necessary for its anti-apoptotic functions. As for Raf-1, its kinase activity, its ability to be phosphorylated by Src on Tyr-340/341 and the binding of its Ras-associated domain to the Grb10 SH2 domain are all necessary to promote cell survival. Silencing the expression of either Grb10 or Raf-1 by small interfering RNAs as well as mutagenesis of specific serine residues on Bad, coupled with signaling inhibitor studies, all indicate that Raf-1 and Grb10 are required for the ability of both the phosphatidylinositol 3-kinase/Akt and MAP kinase pathways to modulate the phosphorylation and inactivation of Bad. Because total Raf-1, ERK, and Akt kinase activities are not impaired in the absence of Grb10, we propose that this adapter protein creates a subpopulation of Raf-1 with specific anti-apoptotic activity.", 
  "author": [
    {
      "family": "Andr\u00e9 Nantel"
    }, 
    {
      "family": "Andr\u00e9 Nantel"
    }, 
    {
      "family": "Colin L. Stewart"
    }, 
    {
      "family": "Maria Huber"
    }, 
    {
      "family": "Matthew G. Annis"
    }, 
    {
      "family": "John P. Hagan"
    }, 
    {
      "family": "Jos\u00e9e Ash"
    }, 
    {
      "family": "Malcolm Whiteway"
    }, 
    {
      "family": "Malcolm Whiteway"
    }, 
    {
      "family": "Sem Kebache"
    }, 
    {
      "family": "Jennifer Hassard"
    }
  ], 
  "id": "95821", 
  "issued": {
    "date-parts": [
      [
        2007, 
        7, 
        1
      ]
    ]
  }, 
  "language": "eng", 
  "note": "", 
  "title": "Grb10 and Active Raf-1 Kinase Promote Bad-dependent Cell Survival", 
  "type": "article-journal"
}