Unique Gene Regulation by Estrogen Receptor Isoforms and Co-regulators in Human Osteoblast Cells

The actions and interactions of the estrogen receptor isoforms with the steroid receptor co-activators SRC-1, -2, and -3, as well as steroid receptor co-repressors, are being investigated at the level of gene transcription by Dr. David Monroe and Barbara Getz (funded by NIH grant AG04875). We have found that the SRCs show specificity for one of the two ER isoforms in regulating gene transcription. Current studies using GST pull-down analysis, followed by western blotting or tandem mass spectrometry are currently underway to assess the differential interactions of these nuclear co-regulatory factors with the estrogen receptor when the latter is bound with either estrogen or SERMs, including raloxifene and tamoxifen.