- Contains a functional disruption of the estrogen receptor beta (Esr2) gene
- Estrogen receptor alpha (Esr1) remains functional
- Esr2 encodes a 60 kDa protein, 527-630 amino acids long
- Male and female homozygotes completely lack functional ERbeta proteins, develop normally and survive into adulthood
- Male homozygotes are significantly more aggressive than wild type males, particularly in the pubertal and young adult age group
- Fertility is normal in males, though aged males develop prostatic and urinary bladder hyperplasia
- Female homozygotes display reduced fertility, due to decreased rates of spontaneous ovulation, increased follicular atresia, decreased cellular mass of the oocyte cumulus, and an inadequate response to exogenous hormones
- Female homozygotes have normal mammary gland development and lactation, but display subnormal fertility ranging from fewer litters and smaller litter sizes to infertility
- An excellent model to study the role of estrogen receptors in development and maintenance of both reproductive and non-reproductive tissues, fertility, sexual behavior, bone homeostasis, and the cardiovascular system.
Genetic Background: C57BL/6
Origin: The ERKO-β mouse was developed by Oliver Smithies and John Kreg of the University of North Carolina, Kenneth Korach of NIEHS and Jan-Ake Gustafsson of the Karolinska Institute. The model was created by targeting the Esr2 gene in ES cells of the BK4 subline of E14TG2a (129P2/OlaHsd) and injecting the targeted ES cells into C57BL/6 blastocysts. Resultant chimeras were backcrossed to C57BL/6 for eight generations (N8). Heterozygotes were intercrossed to generate homozygous ERKO-β mice. Taconic received stock from NIEHS in January 2001 and animals were transferred to Taconic for commercial production in September 2001. The mice were derived by embryo transfer through backcrossing to C57BL/6NTac (N9). The colony was maintained through mating of homozygous males to heterozygous females.
Krege JH, Hodgin JB, Couse JF, Enmark E, Warner M, Mahler JF, Madhabananda S, Korach KS, Gustaffson JA, Smithies O. (1998) Generation and reproductive phenotypes of mice lacking estrogen receptor b
. PNAS USA. 95:15677-15682