Abstract
The Akt protooncogene encodes a serine-threonine protein kinase which is activated by growth factor-generated signals that are transduced via the phosphatidyl-inositol 3'-kinase (PI3-K). Earlier studies suggested that the activation of Akt by PI3-K may be mediated by the binding of D3- phosphorylated phosphoinositides to the Akt pleckstrin homology (PH) domain. On the basis of these studies, it was hypothesized that Akt is a direct PI3- K target. To test this hypothesis, we reconstituted the pathway of Akt activation in baculovirus-infected Sf9 cells. The results showed that Akt, which is normally catalytically inactive in these cells, was activated when coexpressed with the activated PI3-K. Moreover, they showed that activated forms of c-Ha-ras (v-Ha-ras) and c-src (v-src or srcY527F), two molecules that transduce growth factor-generated signals, also activate Akt in a PI3- K-dependent manner in SP9 as well as NIH 3T3 cells. The activation of Akt by both growth factors and v-ras and v-src (or srcY527F) depends on the integrity of the Akt PH domain and carboxyl-terminal tail. These results show that Akt activation via the PI3-K can be faithfully reproduced in baculovirus-infected Sf9 cells. The same results support the hypothesis that Akt is a direct target of the PI3-K and identify cytoplasmic signaling molecules that may contribute to the transduction of PI3-K/Akt activation signals.
Original language | English |
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Pages (from-to) | 30835-30839 |
Number of pages | 5 |
Journal | Journal of Biological Chemistry |
Volume | 271 |
Issue number | 48 |
DOIs | |
State | Published - 1996 |
Keywords
- 3T3 Cells
- Animals
- Cell Line
- Enzyme Activation
- Growth Substances/physiology
- Mice
- Oncogene Protein p21(ras)/metabolism
- Oncogene Protein pp60(v-src)/metabolism
- Phosphatidylinositol 3-Kinases
- Phosphotransferases (Alcohol Group Acceptor)/metabolism
- Protein Serine-Threonine Kinases/chemistry
- Proto-Oncogene Proteins c-akt
- Proto-Oncogene Proteins/chemistry
- Recombinant Proteins
- Signal Transduction
- Spodoptera
- Structure-Activity Relationship