Abstract
The p85α subunit of phosphatidylinositol 3-kinase (PI-3k) forms a complex with a protein network associated with oncogenic fusion tyrosine kinases (FTKs) such as BCR/ABL, TEL/ABL, TEL/JAK2, TEL/PDGFβR, and NPM/ALK, resulting in constitutive activation of the p110 catalytic subunit of PI-3k. Introduction of point mutations in the N-terminal and C-terminal SH2 domain and SH3 domain of p85α, which disrupt their ability to bind phosphotyrosine and proline-rich motifs, respectively, abrogated their interaction with the BCR/ABL protein network. The p85α mutant protein (p85mut) bearing these mutations was unable to interact with BCR/ABL and other FTKs, while its binding to the p110α catalytic subunit of PI-3k was intact. In addition, binding of She, c-Cbl, and Gab2, but not Crk-L, to p85mut was abrogated. p85mut diminished BCR/ABL-dependent activation of PI-3k and Akt kinase, the downstream effector of PI-3k. This effect was associated with the inhibition of BCR/ABL-dependent growth of the hematopoietic cell line and murine bone marrow cells. Interestingly, the addition of interleukin-3 (IL-3) rescued BCR/ABL-transformed cells from the inhibitory effect of p85mut. SCID mice injected with BCR/ABL-positive hematopoietic cells expressing p85mut survived longer than the animals inoculated with BCR/ABL-transformed counterparts. In conclusion, we have identified the domains of p85α responsible for the interaction with the FTK protein network and transduction of leukemogenic signaling.
Original language | English |
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Pages (from-to) | 8001-8008 |
Number of pages | 8 |
Journal | Molecular and Cellular Biology |
Volume | 25 |
Issue number | 18 |
DOIs | |
State | Published - Sep 2005 |
Keywords
- Adaptor Proteins, Signal Transducing/metabolism
- Animals
- Cattle
- Cell Line
- Cell Transformation, Neoplastic/genetics
- Fusion Proteins, bcr-abl/metabolism
- Humans
- Leukemia/genetics
- Mice
- Mice, SCID
- Mutation
- Phosphatidylinositol 3-Kinases/chemistry
- Phosphotyrosine/metabolism
- Protein Interaction Mapping
- src Homology Domains