B6.129P2-Esr1^tm1Ksk/J

Stock number: 004744
Product name: ERα KO
Research areas: Developmental Biology Research, Internal/Organ Research, Neurobiology Research, Reproductive Biology Research

Description

This Esr1 mutant strain is a functional knock out of ERα. Female mice homozygous for this mutation are infertile, exhibit cystic ovaries that lack corpora lutea and hypoplastic uteri that are unresponsive to estrogen. Homozygous males show reduced testis weight associated with diminished sperm count. These mice may be suitable for use in studies related to estrogen signaling, estrous cycle, obesity, metabolic syndrome and hormonal regulation of a variety of organ systems.

Please note: Mice carrying this Esr1^tm1Ksk allele (Stock No. 004744), express a low level of a truncated form of ERα, the result of alternate splicing of the transcript. In contrast, mice carrying the Esr1^tm4.2Ksk allele (Stock No. 026176) have no tissue responses to estrogen and no estrogen receptor alpha activity.

Detailed description

The targeted Esr1 gene encodes a ligand-activated transcription factor and nuclear estradiol hormone receptor. In the ERKO line (Stock #004744) multiple transcript variants may form due to alternative cryptic splicing of the endogenous mouse Esr1 gene. These mice carry an insertional disruption mutation of the Esr1 gene in which exon 2 has been deleted and a series of stop codons have been inserted. Two truncated mutant transcripts and a truncated protein (approximately 61kDa in size) having a deleted N-terminus are detected in uterine tissue from homozygous female mice by RT-PCR and Western blot analysis. At birth, mice homozygous for the targeted allele are viable and normal in size and appearance. Female homozygous mice are infertile, exhibit cystic ovaries that lack corpora lutea and have hypoplastic uteri that are unresponsive to estrogen. Homozygous males are infertile, low normal testis weight as adults and diminished sperm count (10% of normal. Homozygous females have more than 4-fold higher level of serum estradiol and elevated androgen levels compared to wildtype controls, indicative of estrogen insensitivity. There is approximately 3% of the Estradiol binding in uterine tissue from homozygotes compared to levels observed in wildtype controls; no estradiol binding is detected in other tissues (brain, kidney, and liver) from homozygotes. Female neuroendocrine estrogen negative feedback is disrupted with highly elevated LH, normal FSH levels but no prolactin.

Please note: Mice carrying this Esr1^tm1Ksk allele (Stock No. 004744), express a low level of a truncated form of ERα, the result of alternate splicing of the transcript. In contrast, mice carrying the Esr1^tm4.2Ksk allele (Stock No. 026176) have no tissue responses to estrogen and no estrogen receptor alpha activity.

Development

A targeting vector containing a neomycin resistance gene driven by the mouse phosphoglycerate kinase promoter, and polyA signal sequence, was used to disrupt the second exon of the targeted gene. A herpes simplex virus thymidine kinase was used for negative selection. The construct was electroporated into 129P2/OlaHsd-derived E14TG2a embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. Correctly targeted ES cells were injected into C57BL/6J blastocysts to obtain chimeric animals. This strain originated on a B6;129P2 background and has been backcrossed to C57BL/6 for ten generations.

Allele

Symbol: Esr1^tm1Ksk
Name: targeted mutation 1, Kenneth S Korach
MGI accession ID: MGI:2150897
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Esr1
Marker name: estrogen receptor 1 (alpha)
Chromosome: 10
Strain of origin: 129P2/OlaHsd
Molecular note: Insertion of a PGK-neomycin resistance cassette into exon 2 disrupted the reading frame downstream of the ATG start site. ELISA studies using antibodies to the carboxy terminus detected low concentrations of endogenous protein in uterine tissue from homozygous mutant mice. RT-PCR analysis detected two truncated mutant transcripts in uterine tissue from homozygous mice. Western blot analysis detected a 61 kDa protein in uterine tissue from homozygotes. Transient transfection assays confirmed that this protein retains some transactivation activity in the presence of estradiol.