The targeted Esr2 gene encodes the nuclear receptor estrogen receptor-beta, and is expressed broadly throughout the mouse. These Esr2-iCre mice have iCre (codon-improved Cre recombinase) inserted into the initiation codon site of exon 2 of the Esr2 gene, which encodes DNA binding central C domain of estrogen receptor beta. When crossed with a strain containing loxP site flanked sequence of interest, Cre-mediated recombination results in deletion of the floxed sequence in the cre expressing tissues. iCre recombinase expression mimics the endogenous Esr2 gene expression pattern.
Cre recombinase expression is detected in pituitary, hypothalamus, mucosa of the colon and cecum, lung, respiratory epithelium, skeletal muscle, ovarian granulosa, theca and stroma cells, testes (seminiferous tubule interstitium, Leydig cells), epididymis, ductus deferens, coagulation gland (anterior prostate) epithelium, and prepucial glands.
Punctate Cre recombinase activity is detected in mice 2 months of age or older, in the epithelial cells and in the muscularis layer of the oviduct, uterus, stratified mucosa of vagina, rete testes epithelium, epididymal epithelium at the head and tail, vas deferens epithelium, cerebral forebrain neurons, cerebellum and ventral cerebrum, cardiac epicardium and atrial myocardium, salivary glands, adrenal gland, and mucosa/submucosa of intestine.
Low levels of expression is detected in detrusor muscle of the bladder, cornea, Peyers patches, pancreas, pads of feet, and in a few cells per hair follicle.
Of note, when maternally inherited the Esr2-iCre allele may have widespread expression (due to expression in some oocytes).
No gene product (mRNA) is detected by RT-PCR analysis of ovary tissue from homozygous females.
Male mice that are homozygous for the targeted mutation are viable and fertile, but female homozygotes are infertile and exhibit irregular cyclicality with longer periods of estrus or diestrus.
Heterozygotes are viable and fertile.