A new epitope-tagged estrogen receptor-beta mouse model to facilitate the study of estrogen receptor-beta in disease biology

About This Grant

Summary Multiple diseases, impacting diverse organ systems, exhibit sexual dimorphism in both their incidence and outcome. These differences can often be attributed to the actions of sex hormones such that nearly 50 FDA- approved therapeutics target the androgen and estrogen receptors. The ability to identify sex hormone receptor protein levels unambiguously is fundamental to the study of sex hormone-dependent disease biology and the development of the life-sparing therapeutics that target these receptors. Antibodies for estrogen receptor subtype beta are notoriously unreliable which has severely hindered the study of estrogen receptor beta in disease biology and limited the successful development of estrogen receptor beta-targeted agents. Two selective estrogen receptor beta agonists have entered clinical trials with neither gaining FDA approval. Compelling reports of efficacy using estrogen receptor beta agonists in preclinical models continue to be published. Before further development of these agents can be considered, confusion surrounding the role of estrogen receptor beta in disease biology must be resolved. The long-term goal is to develop therapeutic selective estrogen receptor beta agonists to deploy in cardiovascular, metabolic, inflammatory, and neoplastic diseases. The overall objective of the proposal is to develop an epitope-tagged estrogen receptor beta mouse model to unambiguously identify estrogen receptor beta protein levels in vivo and characterize changes in estrogen receptor beta protein expression in models of disease. Our central hypothesis is that using CRISPR methodologies to epitope tag murine estrogen receptor beta with the eleven amino acid HiBiT peptide will afford sensitive and specific detection of in vivo estrogen receptor beta in its endogenous genomic context using validated technology and commercially available reagents. This hypothesis is based on feasibility demonstrated by previous in vitro studies using the HiBiT epitope successfully on estrogen receptors, in vivo studies using CRISPR to generate a variety of epitope-tagged protein mouse models, and an in vivo study using CRISPR to HiBiT epitope-tag a different mouse protein. The rationale for the research is that the inability to unambiguously identify estrogen receptor beta protein is the principal limitation to the successful development of estrogen receptor beta-targeted therapy. Our hypothesis will be tested by pursuing two specific aims: 1) Characterize HiBiT-tagged estrogen receptor beta in healthy mice, and 2) Characterize HiBiT-tagged estrogen receptor beta in disease model mice. In the first Aim, in-depth characterization of epitope-tagged estrogen receptor beta expression and function will be performed in healthy mice, and in Aim 2, characterization of epitope-tagged estrogen receptor beta protein will be performed in disease models reported to be responsive to estrogen receptor beta-selective agonists . The proposed research seeks to clarify the role of estrogen receptor beta in disease biology and ultimately help identify patient populations likely to respond to estrogen receptor beta-targeted agents.