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Impaired Female Reproductive Function in A Novel Estrogen Receptor Alpha Hypomorphic Mouse Model
Author(s) -
Saito Kenji,
Rodeghiero Samuel R.,
Dickey Jacob E.,
Paradee William J.,
Cui Huxing
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.02633
Subject(s) - biology , estrogen receptor , estrogen receptor alpha , mutant , exon , endocrinology , estrogen , medicine , alternative splicing , knockout mouse , estrous cycle , gene , microbiology and biotechnology , genetics , cancer , breast cancer
Estrogen signaling plays an important role in the regulation of both energy homeostasis and reproductive function. Human and animal studies indicate that the metabolic actions of estrogen signaling are primarily mediated by estrogen receptor alpha (ERα). Both human and mouse ERα genes show remarkable heterogeneity due to complicated alternative splicing, which results in a wide variety of variant transcripts with different protein products or a common protein. However, functional significance of this ERα genomic complexity has not been well documented. Here we generated a novel mouse model in which ERα expression was differentially affected in various tissues, and examined their body weight change and reproduction. Method Using CRISPR/Cas9 technology, we introduced a loxP‐flanked sequence containing En2 splice acceptor, a green fluorescent marker with mitochondrial localization signal and DNA translation stop signals before the first coding exon of mouse ERα gene for the potential restoration of the ERα expression. Results ERα protein expressions were significantly reduced in pituitary (~37%) and ovary (~67%), but not in brain, of the homozygous mutant female compared to those of controls, indicating that unknown elements important for ERα tissue‐specific expression were affected. In contrast to body weight gain observed in previous studies of ERα knockout female mice, our hypomorphic mutant females did not show significant body weight gain. On the other hand, virginal smears from the mutant females rarely showed typical estrus stage. Uterine wet weight was significantly lower in the mutant female mice compared to the controls, indicating abnormal reproductive system. Continuous mating study further confirmed delayed pregnancy and inability to have alive newborns in the mutant female mice. Conclusion Estrogen receptor alpha protein expression varies among tissues in terms of the level and pattern of splicing variants. Splicing variant‐specific ERα functions are not fully elucidated. Our results suggest that a particular variant affected in our mouse model is less critical for proper functioning of systems involved in estrogen‐regulated energy metabolism, but indispensable for some aspects of female reproductive function.