Phosphorylation of human estrogen receptor α at serine 118 by two distinct signal transduction pathways revealed by phosphorylation-specific antisera

• Published in: Oncogene Vol. 21; no. 32; pp. 4921 - 4931
• Main Authors: DONGSHENG CHEN, WASHBROOK, Elinor, COOMBES, R. Charles, ALI, Simak, SARWAR, Naveed, BATES, Gaynor J, PACE, Paul E, THIRUNUVAKKARASU, Vatsala, TAYLOR, Jacqueline, EPSTEIN, Richard J, FULLER-PACE, Frances V, EGLY, Jean-Marc
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing 25-07-2002; Nature Publishing Group; Nature Publishing Group [1987-....]
• Subjects: Amino Acid Sequence; Animals; Antibodies; Antisera; Biological and medical sciences; Breast cancer; Breast Neoplasms - metabolism; Cancer; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; COS Cells; Cyclin-Dependent Kinases; Estradiol - analogs & derivatives; Estradiol - pharmacology; Estrogen Antagonists - pharmacology; Estrogen Receptor alpha; Estrogen receptors; Estrogens; Estrogens - metabolism; Extracellular signal-regulated kinase; Fundamental and applied biological sciences. Psychology; Gene expression; Humans; Immunoblotting; Kinases; Life Sciences; Ligands; MAP kinase; Mitogen-Activated Protein Kinases - metabolism; Molecular and cellular biology; Molecular Sequence Data; Phosphorylation; Protein kinase; Protein kinase C; Protein-Serine-Threonine Kinases - metabolism; Receptors, Estrogen - agonists; Receptors, Estrogen - chemistry; Receptors, Estrogen - metabolism; Serine; Serine - metabolism; Signal Transduction; Tamoxifen - analogs & derivatives; Tamoxifen - pharmacology; Transcription activation; Tumors; Human; Signal transduction; Phosphorylation; Antiserum; Cell line; Breast disease; Estrogen; Receiver; Tumor; Onc gene; estrogen receptor α, phosphorylation, MAP kinase, TFIIH, breast cancer
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1205420

Estrogen receptor alpha (ERalpha) is a transcription factor that regulates expression of target genes in a ligand-dependent manner. Activation of gene expression is mediated by two transcription activation functions AF-1 and AF-2, which act in a promoter- and cell-specific manner. Whilst AF-2 activity is regulated by estrogen (E2) binding, the activity of AF-1 is additionally modulated by phosphorylation at several sites. One of these phosphorylation sites, serine 118 (S118) is of particular interest as its mutation significantly reduces ERalpha activity. Previous studies have shown that S118 can be phosphorylated by the ERK1/2 mitogen activated protein kinases (MAPK) and by the cyclin-dependent protein kinase Cdk7. In this study we use antisera that specifically recognize ERalpha phosphorylated at S118 to demonstrate that MAPK phosphorylates S118 in a ligand-independent manner, whereas Cdk7 mediates E2-induced phosphorylation of S118. E2 stimulation of S118 phosphorylation was observed within 10 min of its addition and was maximal at 10(-7) M E2. S118 phosphorylation was maximal at 30 min but then declined, such that by 180 min following E2 addition little S118 phosphorylation was evident. S118 phosphorylation was also induced by the partial estrogen antagonist 4-hydroxytamoxifen, but not by the complete antagonist ICI 182, 780. S118 phosphorylation upon addition of the MAPK inducers EGF or PMA followed the expected time courses. Finally, we show that ERalpha is phosphorylated at S118 in vivo using immunoblotting of extracts prepared from a series of ERalpha-positive breast tumours.