Estradiol (E2) binds to Estrogen Receptor alpha (ERα) activation functions (AF-1 and -2) and regulates gene transcription. A fraction of ERa is targeted to plasma membrane and elicits membrane-initiated steroid signalling (MISS) but its physiological role has never been directly investigated in vivo.

We thus generated a mouse mutated for the palmitoylation site (C451A-ERα) by homologous recombination, leading to an abrogation of membrane localization of ERα.

Surprisingly, this single mutation leads to total female infertility with abnormal ovaries lacking corpus luteum and hence low progesterone production. However, E2 proliferative action was completely preserved in the uterus of C451A-ERa mutant mice and endometrial epithelial proliferation was similar to wild-type. On the opposite, E2 vascular effects, such as rapid dilatation, acceleration of endothelial healing and endothelial NO synthase phosphorylation were abrogated in arteries of C451A-ERa mice.

In striking contrast, in mice inactivated for genomic effects (ERa-AF2°), acceleration of re-endothelialization using membrane-selective activator estrogen-dendrimer conjugate (EDC) was preserved, demonstrating the integrity of the MISS actions in ERa-AF2°. Using a large scale analysis of uterine gene expression, almost all uterine E2-dependent gene expression was abrogated in ERa-AF2°, whereas in C451A mice, gene regulation was essentially similar to wild-type, revealing that this uterine transcriptional response depends primarily on genomic/nuclear functions of ERα.

These models provide evidence for the first time of the physiological role of MISS effects of ERα in vivo and delineate tissue specific roles of membrane and nuclear actions of ERα.