Stress kinase signaling regulates androgen receptor phosphorylation, transcription, and localization.
Activation of signal transduction kinase cascades is known to alter androgen receptor (AR) activity, but the molecular mechanisms are still poorly defined. Here we show that stress kinase signaling regulates Ser 650 phosphorylation and AR nuclear export. In LNCaP prostate cancer cells, activation of either MAPK kinase (MKK) 4:c-Jun N-terminal kinase (JNK) or MKK6:p38 signaling pathways increased Ser 650 phosphorylation, whereas pharmacologic inhibition of JNK or p38 signaling led to a reduction of AR Ser 650 phosphorylation. Both p38alpha and JNK1 phosphorylated Ser 650 in vitro. Small interfering RNA-mediated knockdown of either MKK4 or MKK6 increased endogenous prostate-specific antigen (PSA) transcript levels, and this increase was blocked by either bicalutamide or AR small interfering RNA. Stress kinase inhibition of PSA transcription is, therefore, dependent on the AR. Similar experiments involving either activation or inhibition of MAPK/ERK kinase:ERK signaling had little effect on Ser 650 phosphorylation or PSA mRNA levels. Ser 650 is proximal to the DNA binding domain that contains a nuclear export signal. Mutation of Ser 650 to alanine reduced nuclear export of the AR, whereas mutation of Ser 650 to the phosphomimetic amino acid aspartate restored AR nuclear export. Pharmacologic inhibition of stress kinase signaling reduced wild-type AR nuclear export equivalent to the S650A mutant without affecting nuclear export of the S650D mutant. Our data suggest that stress kinase signaling and nuclear export regulate AR transcriptional activity.
Gioeli
Daniel
D
Department of Microbiology, P.O. Box 800734, University of Virginia Health System, Charlottesville, Virginia 22908, USA. dgg3f@virginia.edu
Black
Ben E
BE
Gordon
Vicki
V
Spencer
Adam
A
Kesler
Cristina T
CT
Eblen
Scott T
ST
Paschal
Bryce M
BM
Weber
Michael J
MJ
D021581:Active Transport, Cell Nucleus; D000726:Androgen Antagonists / Q000494:pharmacology; D059002:Androgen Receptor Antagonists; D000813:Anilides / Q000494:pharmacology; D045744:Cell Line, Tumor; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000235:genetics / Q000378:metabolism; D048669:MAP Kinase Kinase 6 / Q000235:genetics / Q000378:metabolism; D008297:Male; D009154:Mutation; D009570:Nitriles; D010766:Phosphorylation; D017430:Prostate-Specific Antigen / Q000235:genetics / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism*; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D013312:Stress, Physiological; D014105:Tosyl Compounds; D014158:Transcription, Genetic; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
C410798:AR protein, human; D000726:Androgen Antagonists; D059002:Androgen Receptor Antagonists; D000813:Anilides; D004791:Enzyme Inhibitors; D009570:Nitriles; D011944:Receptors, Androgen; D014105:Tosyl Compounds; D012694:Serine; C053541:bicalutamide; D011494:Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D048669:MAP Kinase Kinase 6; C482566:MAP2K6 protein, human; D017430:Prostate-Specific Antigen