© 2001 Annual Reviews
Estrogen's direct genomic effects are mediated by the nuclear form of the estrogen receptors ERα or ERβ which associate with the Estrogen Response Element (ERE) or the fos/jun heterodimers that bind AP1 sites. Indirect genomic mechanisms include activation of ER-linked second messenger systems such as AC/PKC, cAMP/PKA and MAPK/ERK. Ras activates Raf, leading to sequential phosphorylation and activation of MAPK/ERK which interacts directly with nuclear transcription factors and indirectly through interaction with intermediary proteins. Non-genomic effects at high concentrations involve antioxidant effects not mediated by known ERs. (Reprinted with permission,
Classic theories on steroid hormone action have been undergoing considerable revision owing to cellular effects that occur too quickly to be mediated by gene transcription. Estrogen is no exception and plays a leading role as the story unfolds. A growing acceptance that estrogen receptors exist on the cell membrane forces ...