The pleckstrin homology domain of Gab-2 is required for optimal interleukin-3 signalsome-mediated responses.
The adaptor protein Gab-2 coordinates the assembly of the IL-3 signalsome comprising Gab-2, Grb2, Shc, SHP-2 and PI3K. To investigate the role of the pleckstrin homology domain of Gab-2 in this process, epitope-tagged wild type Gab-2 (WTGab-2), Gab-2 lacking its PH domain (DeltaPHGab-2) and the Gab-2 PH domain alone (PHGab-2) were inducibly expressed in IL-3-dependent BaF/3 cells. Expression of DeltaPHGab-2 reduced IL-3-dependent proliferation and long-term activation of ERK1 and 2 and PKB by IL-3. While we demonstrate that the Gab-2 PH domain can bind PI(3,4,5)P3, it is dispensable for Gab-2 membrane localisation, tyrosine phosphorylation and signalsome formation. Rather, the proline-rich motifs of Gab-2 appear to contribute to the constitutive membrane localisation we observe, independently of tyrosine phosphorylation or the PH domain. Taken together, these findings suggest that once Gab-2 is tyrosine phosphorylated its PH domain is required for the optimal stabilisation of the signalsome, enabling full activation of downstream signals.
Edmead
Christine E
CE
Department of Pharmacy and Pharmacology, The University of Bath, Bath, BA2 7AY, UK.
Fox
Bridget C
BC
Stace
Catherine
C
Ktistakis
Nicholas
N
Welham
Melanie J
MJ
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism; D007377:Interleukin-3 / Q000494:pharmacology*; D051379:Mice; D009154:Mutation / Q000235:genetics; D010716:Phosphatidylinositols / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
D048868:Adaptor Proteins, Signal Transducing; C490894:Gab2 protein, mouse; D007295:Inositol Phosphates; D007377:Interleukin-3; D010716:Phosphatidylinositols; D010750:Phosphoproteins; C118303:phosphoinositide-3,4,5-triphosphate; C066454:inositol 4,5-bisphosphate; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases