c-Abl regulates estrogen receptor alpha transcription activity through its stabilization by phosphorylation.
Estrogen receptors are members of the steroid hormone superfamily of nuclear receptors that act as ligand-activated transcription factors. Similar to other steroid hormone receptors, estrogen receptor alpha (ERalpha) is a substrate for protein kinases, and phosphorylation has profound effects on the function of this receptor. In this study, we show that ERalpha associates with c-Abl nonreceptor tyrosine kinase. The direct interaction is mediated by two PXXP motifs of ERalpha and the c-Abl SH3 domain. Mutational analysis and in vitro kinase assays show that ERalpha can be phosphorylated on two sites, tyrosine 52 (Y-52) and tyrosine 219 (Y-219). ERalpha phosphorylation by c-Abl stabilizes ERalpha, resulting in enhanced ERalpha transcriptional activity and increased expression of endogenous ERalpha target genes. Furthermore, ERalpha phosphorylation at the Y-219 site affects DNA binding and dimerization by ERalpha. Both the c-Abl inhibitor and the c-Abl kinase dead mutation abolish the c-Abl-induced accumulation of ERalpha and enhancement of ERalpha transcriptional activity, indicating that c-Abl kinase activity is required for regulation of the ERalpha function. Moreover, the ERalpha (Y52,219F) mutant shows reduced breast cancer cell growth and invasion. Taken together, these results show that c-Abl is a novel kinase that upregulates ERalpha expression and promotes breast cancer cell proliferation, suggesting a great potential for this kinase to function as a therapeutic target for breast cancer.
He
X
X
State key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, PR China.
Zheng
Z
Z
Song
T
T
Wei
C
C
Ma
H
H
Ma
Q
Q
Zhang
Y
Y
Xu
Y
Y
Shi
W
W
Ye
Q
Q
Zhong
H
H
D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004247:DNA / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D009154:Mutation; D009361:Neoplasm Invasiveness; D010766:Phosphorylation; D055503:Protein Multimerization; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic; D015854:Up-Regulation
D047628:Estrogen Receptor alpha; D004247:DNA; D016315:Proto-Oncogene Proteins c-abl