Phosphatidylinositol 3-kinase signaling does not activate the wnt cascade.
Mutational activation of the phosphatidylinositol 3-kinase (PI3K) pathway occurs in a wide variety of tumors, whereas activating Wnt pathway mutants are predominantly found in colon cancer. Because GSK3 is a key component of both pathways, it is widely assumed that active PI3K signaling feeds positively into the Wnt pathway by protein kinase B (PKB)-mediatefd inhibition of GSK3. In addition, PKB has been proposed to modulate the canonical Wnt signaling through direct stabilization and nuclear localization of beta-catenin. Here, we show that compartmentalization by Axin of GSK3 prohibits cross-talk between the PI3K and Wnt pathways and that Wnt-mediated transcriptional activity is not modulated by activation of the PI3K/PKB pathway.
Ng
Ser Sue
SS
Hubrecht Institute-KNAW and University Medical Centre Utrecht, Uppsalalaan 8, 3584CT Utrecht.
Mahmoudi
Tokameh
T
Danenberg
Esther
E
Bejaoui
Inés
I
de Lau
Wim
W
Korswagen
Hendrik C
HC
Schutte
Mieke
M
Clevers
Hans
H
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014158:Transcription, Genetic / Q000502:physiology; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
D029742:Caenorhabditis elegans Proteins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D051153:Wnt Proteins; D051176:beta Catenin; C527979:gck-3 protein, C elegans