AF2ER mice carry leucine to alanine missense mutations at amino acids 543 and 544 in exon 9 of the estrogen receptor 1 (alpha) (Esr1) gene, which is associated with insensitivity to estradiol, the natural ligand for Esr1. This strain may be useful in studies of AF-1 mediated physiological functions and its role in regulating female reproductive tissue hormone responses.
Kenneth Korach, LRDT, NIEHS, NIH
AF2ER mice have leucine to alanine missense mutations at amino acids 543 and 544 in exon 9 of the estrogen receptor 1 (alpha) (Esr1) gene. ESR1 encodes a nuclear hormone receptor that is predominantly expressed in the uterus, mammary glands, pituitary, hypothalamus, and ovarian theca cells and is important for hormone binding, DNA binding, and activation of transcription. The protein localizes to the nucleus where it may form a homodimer or a heterodimer with estrogen receptor 2 (ESR2). Estrogen and its receptors are essential for sexual development and reproductive function, but also play a role in other tissues such as bone. Estrogen receptors are also involved in pathological processes including breast cancer, endometrial cancer, and osteoporosis. Exon 9 encodes the AF-2 motif in the C terminal ligand binding domain. The mutated residues correlate with L539 and L540 residues of human ESR1 protein which have been found to be involved in determining interactions with coactivators and corepressors for transcriptional regulation influencing agonist or antagonist effects of the ligand. Disruption of these residues has been shown to convey insensitivity to estradiol, the natural ligand for ESR1. Sequence encoding a carboxy terminal histidine epitope tag is also present.
AF2ER mice recapitulate the phenotype of the Esr1-null model, except they have phenotypes that can be rescued by treatments with fulvestrant or tamoxifen, due to activation of AF-1. Female mice have hypoplastic uterine tissue and rudimentary mammary glands similar to Esr1-null mice. Female mice are infertile as a result of anovulation from hemorrhagic cystic ovaries, and elevated serum luteinizing homone and estradiol levels.
Mice that are homozygous for this allele are viable but infertile.
The AF2ER targeting vector was designed to insert leucine to alanine missense mutations at amino acids 543 and 544 in exon 9 of the estrogen receptor 1 (alpha) (Esr1) gene, and a self-excising ACN cassette was inserted in to the 3’ UTR. The ACN cassette, containing the neomycin resistance gene and Cre recombinase gene under the control of angiotensin-converting enzyme promoter, is flanked by loxP sites. Cre-mediated recombination during spermatogenesis removes the cassette leaving one loxP site. The construct was electroporated into 129S6/SvEvTac-derived embryonic stem (ES) cells and targeted ES cells were injected into C57BL/6 blastocysts. Resulting chimeric males were bred with C57BL/6NCrl females, and subsequently these mice were bred to C57BL/6NCrl mice for at least 7 generations. Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6NJ oocytes (Stock No. 005304).
|Allele Name||targeted mutation 3.1, Kenneth S Korach|
|Gene Symbol and Name||Esr1, estrogen receptor 1 (alpha)|
|Strain of Origin||129S6/SvEvTac|
|General Note||ES cells = clone A3 of UG347 ES cells (129S6/SvEvTac)|
|Molecular Note||Missense mutations (leucine to alanine) of the first two codons encoding hydrophobic residues were introduced in exon 9, which encodes the AF-2 motif. Previous in vitro studies showed that the disruption of these residues conferred insensitivity to estradiol. Sequence encoding a carboxy terminal histidine epitope tag was also added to allow for detection of the mutant protein. A self-excising floxed neo cassette that was inserted into the 3' untranslated region was excised via cre recombinase.|
When maintaining a live colony, heterozygous mice may be bred together. Homozygous males and females are viable but infertile.
When using the AF2ERKI mouse strain in a publication, please cite the originating article(s) and include JAX stock #032175 in your Materials and Methods section.