Perinatal induction of Cre recombination with tamoxifen

Abstract

Temporal control of site-specific recombination is commonly achieved by using a tamoxifen-inducible form of Cre or Flp recombinases. Although powerful protocols of induction have been developed for gene inactivation at adult stages or during embryonic development, induction of recombination at late gestational or early postnatal stages is still difficult to achieve. In this context, using the ubiquitous CMV-CreER(T2) transgenic mice, we have tested and validated two procedures to achieve recombination just before and just after birth. The efficiency of recombination was evaluated in the brain, which is known to be more problematic to target. For the late gestation treatment with tamoxifen, different protocols of complementary administration of progesterone and estrogen were tested. However, delayed delivery and/or mortality of pups due to difficult delivery were always observed. To circumvent this problem, pups were collected from tamoxifen-treated pregnant dams by caesarian section at E18.5 and given to foster mothers. For postnatal treatment, different dosages of tamoxifen were administered by intragastric injection to the pups during 3 or 4 days after birth. The efficiency of these treatments was analyzed at P7 using a transgenic reporter line. They were also validated with the Hoxa5 conditional allele. In conclusion, we have developed efficient procedures that allow achieving efficient recombination of floxed alleles at perinatal stages. These protocols will allow investigating the late/adult functions of many developmental genes, whose characterization has been so far restricted to embryonic development.

Conditional Loss of Hoxa5 Function Early after Birth Impacts on Expression of Genes with Synaptic Function

“…For all gas euthanasia, CO 2 was administered by progressive delivery in the cage volume in accordance with guidelines. The transgenic CMV-CreER T2 mice and the characterization of Cre activity with reporter mice have been described elsewhere ( Santagati et al, 2005 ; Lizen et al, 2015 ). We used the Hoxa5 tm1.1Ljea mouse line carrying a Hoxa5 floxed allele as described ( Tabaries et al, 2007 ).…”

Construction of Gpm6a/ReelinGFPCreERT2 by BAC recombination using a specific gene in hepatic mesothelial or stellate cells

“…Cre recombinase is used to delete a segment of DNA flanked by LoxP sites (flox). The ERT2 system is used to activate Cre activity by tamoxifen treatment[10,11]. …”

FGF10 is an essential regulator of tracheal submucosal gland morphogenesis

“…Tamoxifen was injected in combination with progesterone to counter the negative effects of tamoxifen on the ability to give birth naturally (Lizen et al, 2015). At this dose of tamoxifen the recombination of this Cre line is not 100% penetrant (Hayashi & McMahon, 2002).…”