aP2-Cre-mediated inactivation of estrogen receptor alpha causes hydrometra

Per Antonson; Marko Matic; Neil Portwood; Raoul V Kuiper; Galyna Bryzgalova; Hui Gao; Sara H Windahl; Patricia Humire; Claes Ohlsson; Per-Olof Berggren; Jan-Åke Gustafsson; Karin Dahlman-Wright

doi:10.1371/journal.pone.0085581

aP2-Cre-mediated inactivation of estrogen receptor alpha causes hydrometra

PLoS One. 2014 Jan 8;9(1):e85581. doi: 10.1371/journal.pone.0085581. eCollection 2014.

Authors

Affiliations

¹ Department of Biosciences and Nutrition, Karolinska Institutet, Novum, Huddinge, Sweden.
² The Rolf Luft Center for Diabetes and Endocrinology, Karolinska Institutet, Karolinska University Hospital L1, Stockholm, Sweden.
³ Karolinska Institute Phenotyping Core Facility, Department of Laboratory Medicine, Karolinska University Hospital, Huddinge, Sweden.
⁴ Centre for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
⁵ Department of Biosciences and Nutrition, Karolinska Institutet, Novum, Huddinge, Sweden ; Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America.

Abstract

In this study we describe the reproductive phenotypes of a novel mouse model in which Cre-mediated deletion of ERα is regulated by the aP2 (fatty acid binding protein 4) promoter. ERα-floxed mice were crossed with transgenic mice expressing Cre-recombinase under the control of the aP2 promoter to generate aP2-Cre/ERα(flox/flox) mice. As expected, ERα mRNA levels were reduced in adipose tissue, but in addition we also detected an 80% reduction of ERα levels in the hypothalamus of aP2-Cre/ERα(flox/flox) mice. Phenotypic analysis revealed that aP2-Cre/ERα(flox/flox) female mice were infertile. In line with this, aP2-Cre/ERα(flox/flox) female mice did not cycle and presented 3.8-fold elevated estrogen levels. That elevated estrogen levels were associated with increased estrogen signaling was evidenced by increased mRNA levels of the estrogen-regulated genes lactoferrin and aquaporin 5 in the uterus. Furthermore, aP2-Cre/ERα(flox/flox) female mice showed an accumulation of intra-uterine fluid, hydrometra, without overt indications for causative anatomical anomalies. However, the vagina and cervix displayed advanced keratosis with abnormal quantities of accumulating squamous epithelial cells suggesting functional obstruction by keratin plugs. Importantly, treatment of aP2-Cre/ERα(flox/flox) mice with the aromatase inhibitor Letrozole caused regression of the hydrometra phenotype linking increased estrogen levels to the observed phenotype. We propose that in aP2-Cre/ERα(flox/flox) mice, increased serum estrogen levels cause over-stimulation in the uterus and genital tracts resulting in hydrometra and vaginal obstruction.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Estradiol / biosynthesis
Estradiol / blood
Estrogen Receptor alpha / metabolism*
Estrous Cycle / drug effects
Fatty Acid-Binding Proteins / metabolism*
Female
Gene Deletion
Infertility, Female / metabolism
Infertility, Female / pathology
Integrases / metabolism*
Letrozole
Mice
Mice, Knockout
Nitriles / pharmacology
Triazoles / pharmacology
Up-Regulation / drug effects
Up-Regulation / genetics
Uterus / abnormalities*
Uterus / metabolism*
Uterus / pathology
Uterus / physiopathology

Substances

Estrogen Receptor alpha
Fabp4 protein, mouse
Fatty Acid-Binding Proteins
Nitriles
Triazoles
Estradiol
Letrozole
Cre recombinase
Integrases

Grants and funding

This work is supported by the Swedish Research Council (http://www.vr.se/; The involvement of estrogen receptor signaling in insulin resistance and type 2 diabetes (project # K2009-54X-21122-01-3), Estrogen signaling in metabolic disease; a functional genomics approach (project # K2008-54X-20640-01-3) and Tissue-specific estrogen signaling - new insights in metabolic disease development (project # K2011-54X-20640-04-6)), Cancerfonden (http://www.cancerfonden.se; grant # 080482, 090678, 100404, 110588 and 120435), Novo Nordisk Foundation (http://www.novonordiskfonden.dk/en/; Estrogen signaling in metabolic disease (2006), Molecular mechanisms underlying the regulation of body weight and the anti-diabetic effects of estrogen (2008), Genetic dissection of estrogen signaling in mice (2009), Genetic dissection of estrogen signaling in metabolic disease (2011)), the Strategic Research Area in Diabetes at the Karolinska Institute (http://ki.se/srp-diabetes; SFO/TM Diabetes (2010)), Center for Biosciences (http://ki.se/cb;grant#n/a (2009–2011)), the KI Endomet network (http://researchnetworks.ki.se/converis/; grant details n/a), King Gustaf V and Queen Victoria’s Freemason’s Foundation; Molecular Mechanisms Underlying the Antidiabetic Effects of Estrogen (2008, 2009, 2010, 2011). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.