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Calmodulin-independent, agonistic properties of a peptide containing the calmodulin binding site of estrogen receptor α

par Gallo, Dominique ;Jacquemotte, Françoise;Cleeren, Anny ;Laïos, Ioanna;Hadiy, Samira ;Rowlands, Martin G.;Caille, Olivier;Nonclercq, Denis;Laurent, Guy ;Jacquot, Yves;Leclercq, Guy
Référence Molecular and cellular endocrinology, 268, 1-2, page (37-49)
Publication Publié, 2007-03

Article révisé par les pairs

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Résumé :

Calmodulin (CaM) contributes to estrogen receptor α (ER)-mediated transcription. In order to study the underlying mechanisms, we synthesized a peptide including the CaM binding site: ERα17p (P295-T311). This peptide inhibited ER-CaM association, unlike two analogs in which two amino acids required for CaM binding were substituted. Exposure of MCF-7 cells to ERα17p down regulated ER, stimulated ER-dependent transcription and enhanced the proliferation of ER-positive breast cancer cell lines. Interestingly, ERα17p analogs unable to bind to CaM induced similar responses, demonstrating that ERα17p-mediated effects are mainly relevant to mechanisms independent of ER-CaM dissociation. The P295-T311 motif is indeed a platform for multiple post-translational modifications not necessarily CaM-dependent. The additional finding that deletion of the P295-T311 sequence in ER produced a constitutive transcriptional activity revealed that this platform motif has autorepressive functions. With regard to cell function, association of CaM to ER would counteract this autorepression, leading thereby to enhanced ER-mediated transactivation. © 2007 Elsevier Ireland Ltd. All rights reserved.