Interaction of the ligand-activated glucocorticoid receptor with the 14-3-3 eta protein.
The glucocorticoid receptor (GR) is a ligand-activated transcription factor. In this study, we used the yeast two-hybrid system to isolate cDNAs encoding proteins that interact with the human GR ligand-binding domain (LBD) in a ligand-dependent manner. One isolated cDNA from a HeLa cell library encoded the COOH-terminal portion of the eta-isoform of the 14-3-3 protein (residues 187-246). Glucocorticoid agonists, triamcinolone acetonide and dexamethasone, induced the GR LBD/14-3-3eta protein fragment interaction, but an antagonist, RU486, did not. Glutathione S-transferase pull-down experiments in vitro showed that full-length 14-3-3eta protein also interacted with the activated GR. Transient transfection studies using COS-7 cells revealed a stimulatory effect of 14-3-3eta protein on transcriptional activation by the GR. The 14-3-3 family members have recently been found to associate with a number of important signaling proteins, such as protein kinase C and Raf-1, as functional modulators. Our findings suggest a novel regulatory role of 14-3-3eta protein in GR-mediated signaling pathways and also point to a mechanism whereby GR may cross-talk with other signal transduction systems.
Wakui
H
H
Department of Biosciences, Karolinska Institute, NOVUM, S-141 57 Huddinge, Sweden.
Wright
A P
AP
Gustafsson
J
J
Zilliacus
J
J
D048948:14-3-3 Proteins; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D010741:Phospholipases A / Q000037:antagonists & inhibitors*; D010751:Phosphopyruvate Hydratase / Q000037:antagonists & inhibitors*; D011487:Protein Conformation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D015398:Signal Transduction; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D011506:Proteins; D011965:Receptors, Glucocorticoid; C482984:YWHAH protein, human; D014446:Tyrosine 3-Monooxygenase; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010741:Phospholipases A; D010751:Phosphopyruvate Hydratase; D002118:Calcium