Organization of mammary epithelial cells into 3D acinar structures requires glucocorticoid and JNK signaling.
Mammary epithelial cells cultured on a concentrated laminin-rich extracellular matrix formed 3D acinar structures that matured to polarized monolayers surrounding a lumen. In the absence of glucocorticoids mature acinus formation failed and the expression of an acinus-associated, activator protein 1 (AP1) and nuclear factor kappaB transcription factor DNA-binding profile was lost. Treatment with the JNK inhibitor, SP600125, caused similar effects, whereas normal organization of the mammary epithelial cells as acini caused JNK activation in a glucocorticoid-dependent manner. The forming acini expressed BRCA1, GADD45beta, MEKK4, and the JNK activating complex GADD 45beta-MEKK4 in a glucocorticoid-dependent fashion. JNK catalyzed phosphorylation of c-Jun was also detected in the acini. In addition, expression of beta4 integrin and in situ occupation of its promoter by AP1 components, c-Jun and Fos, was glucocorticoid dependent. These results suggest that glucocortocoid signaling regulates acinar integrity through a pathway involving JNK regulation of AP1 transcription factors and beta4 integrin expression.
Murtagh
Janice
J
Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, 4, Ireland.
McArdle
Emmett
E
Gilligan
Emer
E
Thornton
Laura
L
Furlong
Fiona
F
Martin
Finian
F
D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D019313:BRCA1 Protein / Q000378:metabolism; D015153:Blotting, Western; D018929:Cell Culture Techniques / Q000379:methods; D002478:Cells, Cultured; D002843:Chromatin / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology*; D005109:Extracellular Matrix / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism*; D039663:Integrin beta4 / Q000378:metabolism; D016023:Integrins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D007774:Lactation; D008156:Luciferases / Q000378:metabolism; D048670:MAP Kinase Kinase 4; D008321:Mammary Glands, Animal / Q000166:cytology*; D051379:Mice; D008856:Microscopy, Fluorescence; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D008954:Models, Biological; D010766:Phosphorylation; D011233:Precipitin Tests; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014162:Transfection
D000873:Anthracenes; D019313:BRCA1 Protein; D002843:Chromatin; D005938:Glucocorticoids; D039663:Integrin beta4; D016023:Integrins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; C432165:pyrazolanthrone; D008156:Luciferases; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases