We are activating the expression of a gene by Cre mediated removal of a gene trap. Using a CreER driver we want to activate expression starting at E11.5. However after 1 injection with tamoxifen (1mg/10g mice) and progesterone (0.5 mg/10g mice) all our females (6 out of 6) were unable to deliver at E19.5/E20. Any tricks to circumvent this?
Hi Patrick! I am performing a similar procedure with R26R-Confetti mice as reporter system, crossed with several Cre-ER drivers. In out case we found that the susceptibility of the pregant female to the tamoxifen and the abortive effect could depend on the strain. In fact, our other reporter mice don't seem to show the same embryo lethality or adverse effects when tamoxifen+progesteron are administered at E11.5. One thing that we were suggested to do in this case was to scale down the dose (but in our case it would be difficult to have a proper activation of the Cre in our developmental window), or try to cross the female driver with the male reporter in order to circumvent possible oversusceptibility of the reporter strain to tamoxifen.
Which kind of drivers and reporters were you using?
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