Akt/protein kinase b and glycogen synthase kinase-3beta signaling pathway regulates cell migration through the NFAT1 transcription factor.
The phosphoinositide 3-kinase (PI3K) pathway regulates a multitude of cellular processes. Deregulation of PI3K signaling is often observed in human cancers. A major effector of PI3K is Akt/protein kinase B (PKB). Recent studies have pointed to distinct roles of Akt/PKB isoforms in cancer cell signaling. Studies have shown that Akt1 (PKBalpha) can attenuate breast cancer cell motility, whereas Akt2 (PKBbeta) enhances this phenotype. Here, we have evaluated the mechanism by which Akt1 blocks the migration of breast cancer cells through the transcription factor NFAT. A major effector of Akt/PKB is glycogen synthase kinase-3beta (GSK-3beta), also a NFAT kinase. Inhibition of GSK-3beta using short hairpin RNA or a selective inhibitor potently blocks breast cancer cell migration concomitant with a reduction in NFAT activity. GSK-3beta-mediated inhibition of NFAT activity is due to proteasomal degradation. Experiments using GSK-3beta mutants, which are unresponsive to Akt/PKB, reveal that inhibition of cell migration by Akt/PKB is mediated by GSK-3beta. These effects are recapitulated at the levels of NFAT degradation by the proteasome. Our studies show that activation of Akt/PKB leads to inactivation of the effector GSK-3beta and the outcome of this signaling event is degradation of NFAT by the proteasome and subsequent inhibition of cell migration.
Yoeli-Lerner
Merav
M
Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
Chin
Y Rebecca
YR
Hansen
Christopher K
CK
Toker
Alex
A
D019870:1-Phosphatidylinositol 4-Kinase / Q000378:metabolism; D000818:Animals; D001943:Breast Neoplasms / Q000201:enzymology / Q000378:metabolism / Q000473:pathology*; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D002470:Cell Survival; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D051379:Mice; D050778:NFATC Transcription Factors / Q000378:metabolism*; D041681:NIH 3T3 Cells; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism*
D050778:NFATC Transcription Factors; C494006:NFATC2 protein, human; D019870:1-Phosphatidylinositol 4-Kinase; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3; D046988:Proteasome Endopeptidase Complex