Constitutive activation of the Raf-MAPK pathway causes negative feedback inhibition of Ras-PI3K-AKT and cellular arrest through the EphA2 receptor.
The Raf-mitogen-activated protein kinase (MAPK) and phosphatidylinositide 3-kinase (PI3K)-AKT pathways are two downstream effectors of the small GTPase Ras. Although both pathways are positively regulated by Ras, the Raf-MAPK and PI3K-AKT pathways have been shown to control opposing functions within the cell, suggesting a need for cross-talk regulation. The PI3K-AKT pathway can inhibit the Raf-MAPK pathway directly during processes such as muscle differentiation. Here we describe the ability of the Raf-MAPK pathway to negatively regulate the PI3K-AKT pathway during cellular arrest. Constitutive activation of Raf or methyl ethyl ketone 1 (MEK1) leads to inhibition of AKT and cellular arrest. Furthermore, we show that activation of Raf-MEK1 signaling causes negative feedback inhibition of Ras through the ephrin receptor EphA2. EphA2-mediated negative feedback inhibition is required for Raf-induced AKT inhibition and cell cycle arrest, therefore establishing the inhibition of the Ras-PI3K-AKT pathway as a necessary event for the Raf-MEK1-regulated cellular arrest.
Department of Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA.
C W
CW
Menges
D J
DJ
McCance
D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D004789:Enzyme Activation / Q000502:physiology; D025461:Feedback, Physiological / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D041681:NIH 3T3 Cells; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000502:physiology; D036104:Receptor, EphA2 / Q000502:physiology*; D048490:raf Kinases / Q000378:metabolism*; D018631:ras Proteins / Q000037:antagonists & inhibitors* / Q000502:physiology
D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D036104:Receptor, EphA2; D048490:raf Kinases; D018631:ras Proteins