Identification of a Hormone-regulated Dynamic Nuclear Actin Network Associated with Estrogen Receptor α in Human Breast Cancer Cell Nuclei

• DOI: 10.1074/mcp.m900519-mcp200
• Publication Date: 2010-03-23T03:01:27Z
• Authors: Concetta Ambrosino; Roberta Tarallo; Angela Bamundo; Danila Cuomo; Gianluigi Franci; Giovanni Nassa; Ornella Paris; Maria Ravo; Alfonso Giovane; Nicola Zambrano; Tatiana Lepikhova; Olli A. Jänne; Marc Baumann; Tuula A. Nyman; Luigi Cicatiello; Alessandro Weisz
• Keywords: Estrogen receptor alpha

Estrogen receptor alpha (ERalpha) is a modular protein of the steroid/nuclear family transcriptional regulators that upon binding to hormone undergoes structural changes, resulting in its nuclear translocation and docking specific chromatin sites. In nucleus, ERalpha assembles multiprotein complexes act as final effectors estrogen signaling genome through remodeling epigenetic modifications, leading dynamic coordinated regulation hormone-responsive genes. Identification molecular partners understanding their combinatory interactions within functional prerequisite define basis control cell functions. To this end, affinity purification was applied map characterize interactome human breast cancer nuclei. MCF-7 clones expressing fused tandem tag were generated used purify native ER-containing by IgG-Sepharose chromatography glycerol gradient centrifugation. Purified analyzed two-dimensional DIGE mass spectrometry, identification ligand-dependent complex comprising beta-actin, myosins, several proteins involved actin filament organization dynamics and/or known participate actin-mediated gene transcription, dynamics, ribosome biogenesis. Time course analyses indicated containing are assembled nucleus early after activation ligands, knockdown experiments showed gelsolin isoform myosin 1c key determinants for assembly stability these complexes. Based on results, we propose network plays role actions cells, including target activity, spatial reorganization chromatin,