Membrane Estrogen Receptor Beta is Sufficient to Mitigate Cardiac Cell Pathology.

Estrogen acting through estrogen receptor beta has been shown to oppose the stimulation of cardiac myocytes and cardiac fibroblasts that results in cardiac hypertrophy and fibrosis. Previous work has implicated signal transduction from ERβ as being important to the function of estrogen in these regards. Here we address whether membrane ERβ is sufficient to oppose key mechanisms by which Angiotensin II stimulates cardiac cell pathology. To do this we first defined essential structural elements within ERβ that are necessary for membrane or nuclear localization in cells. We previously determined that cysteine 418 is the site of palmitoylation of ERβ that is required and sufficient for cell membrane localization in mice and is the same site in humans. Here we determined in CHO cells, and mouse and rat myocytes and cardiac fibroblasts, the impact on multiple aspects of signal transduction by expressing wild type or a C418A mutant ERβ. To test the importance of the nuclear receptor, we determined a four amino acid deletion in the E domain of ERβ that strongly blocked nuclear localization. Using these tools, we expressed wild type and mutant ERβ constructs into cardiomyocytes and cardiac fibroblasts from ERβ deleted mice. We determined the ability of estrogen to mitigate cell pathology stimulated by Angiotensin II and whether the membrane ERβ is necessary and sufficient.