Androgen receptor phosphorylation. Regulation and identification of the phosphorylation sites.
Activation of signal transduction kinase cascades has been shown to alter androgen receptor (AR) activity. Although it has been suggested that changes in AR phosphorylation might be directly responsible, the basal and regulated phosphorylations of the AR have not been fully determined. We have identified the major sites of AR phosphorylation on ARs expressed in COS-1 cells using a combination of peptide mapping, Edman degradation, and mass spectrometry. We describe the identification of seven AR phosphorylation sites, show that the phosphopeptides seen with exogenously expressed ARs are highly similar to those seen with endogenous ARs in LNCaP cells and show that specific agonists differentially regulate the phosphorylation state of endogenous ARs in LNCaP prostate cancer cells. Treatment of LNCaP cells with the synthetic androgen, R1881, elevates phosphorylation of serines 16, 81, 256, 308, 424, and 650. Ser-94 appears constitutively phosphorylated. Forskolin, epidermal growth factor, and phorbol 12-myristate 13-acetate increase the phosphorylation of Ser-650. The kinetics of phosphorylation of most sites in response to hormone or forskolin is temporally delayed, reaching a maximum at 2 h post-stimulation. The exception is Ser-81, which continues to display increasing phosphorylation at 6 h. These data provide a basis for analyzing mechanisms of cross-talk between growth factor signaling and androgen in prostate development, physiology, and cancer.
Gioeli
Daniel
D
Department of Microbiology and Cancer Center, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908, USA.
Ficarro
Scott B
SB
Kwiek
Jesse J
JJ
Aaronson
David
D
Hancock
Mathew
M
Catling
Andrew D
AD
White
Forest M
FM
Christian
Robert E
RE
Settlage
Robert E
RE
Shabanowitz
Jeffrey
J
Hunt
Donald F
DF
Weber
Michael J
MJ
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002846:Chromatography, Affinity; D005576:Colforsin / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007700:Kinetics; D008024:Ligands; D020935:MAP Kinase Signaling System; D008297:Male; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010748:Phosphopeptides / Q000737:chemistry; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism*; D012694:Serine / Q000737:chemistry; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured
D008024:Ligands; D010455:Peptides; D010748:Phosphopeptides; D011944:Receptors, Androgen; D005576:Colforsin; D012694:Serine; D004815:Epidermal Growth Factor; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate