Hormone-dependent nuclear export of estradiol receptor and DNA synthesis in breast cancer cells.
In breast cancer cells, cytoplasmic localization of the estradiol receptor alpha (ERalpha) regulates estradiol-dependent S phase entry. We identified a nuclear export sequence (NES) in ERalpha and show that its export is dependent on both estradiol-mediated phosphatidylinositol-3-kinase (PI3K)/AKT activation and chromosome region maintenance 1 (CRM1). A Tat peptide containing the ERalpha NES disrupts ERalpha-CRM1 interaction and prevents nuclear export of ERalpha- and estradiol-induced DNA synthesis. NES-ERalpha mutants do not exit the nucleus and inhibit estradiol-induced S phase entry; ERalpha-dependent transcription is normal. ERalpha is associated with Forkhead proteins in the nucleus, and estradiol stimulates nuclear exit of both proteins. ERalpha knockdown or ERalpha NES mutations prevent ERalpha and Forkhead nuclear export. A mutant of forkhead in rhabdomyosarcoma (FKHR), which cannot be phosphorylated by estradiol-activated AKT, does not associate with ERalpha and is trapped in the nucleus, blocking S phase entry. In conclusion, estradiol-induced AKT-dependent phosphorylation of FKHR drives its association with ERalpha, thereby triggering complex export from the nucleus necessary for initiation of DNA synthesis and S phase entry.
Lombardi
Maria
M
Dipartimento di Patologia Generale, Il Università di Napoli, 80138 Naples, Italy.
Castoria
Gabriella
G
Migliaccio
Antimo
A
Barone
Maria Vittoria
MV
Di Stasio
Rosina
R
Ciociola
Alessandra
A
Bottero
Daniela
D
Yamaguchi
Hiroshi
H
Appella
Ettore
E
Auricchio
Ferdinando
F
D021581:Active Transport, Cell Nucleus / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000096:biosynthesis* / Q000235:genetics; D004958:Estradiol / Q000378:metabolism* / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005260:Female; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D018816:Genes, cdc / Q000502:physiology; D006801:Humans; D028884:Karyopherins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009154:Mutation / Q000235:genetics; D041681:NIH 3T3 Cells; D049790:Nuclear Export Signals / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism; D016196:S Phase / Q000235:genetics; D000097606:Exportin 1 Protein
D004273:DNA, Neoplasm; D004958:Estradiol; D047628:Estrogen Receptor alpha; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D028884:Karyopherins; D049790:Nuclear Export Signals; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein; C085126:FOXO1 protein, human