Endothelial Cre Lineage Maps

It is an excellent idea (essential, actually) to know where and when your Cre of choice is active.

I've included images from a few of the more utilized Cre lines below after crossing them into various Rosa26 reporter lines (read more here about choosing a Cre reporter).

The images are of "live" fluorescence, and are not immunostained or amplified. If this is of interest please check back, as I will add other Cre lines to the panel.

Tg(Tie2::Cre)

Whichever transgenic allele you employ (Sato, Wang, etc), they all use the same promoter and enhancer, and thus they all seem to have germline-esque activity at a low, but persistent, frequency. See de Lange et al., 2008 for a reference in the literature.

As you can see below, embryos from the same litter displayed wildly different activities (compare the two on the left vs the one on the right). Make sure to cross a reporter into your background, or you could be interpreting a semi-global null phenotype rather than an EC-specific phenotype (not that Tie2::Cre is EC-specific).

Tie2 Cre Various Activity.jpg

Tg(Cdh5::Cre) (Nancy Speck)

Be aware that at a low level, this can induce germline recombination as well. There are some genotyping strategies you can employ to determine if your reporter has recombined, but in general we wouldn't suggest maintaining this Cre in the same background as your reporter. This reporter differs from the other Cdh5::Cre driver line (Tg(Cdh5-Cre)7Mlia/J from the Iruela-Arispe lab at UCLA, which we have not utilized extensively and cannot comment on germline activity) in that it is flanked by insulator elements, and obviously integrated in a different location (as they were both made via random insertion transgenesis).

Tg(Cdh5(PAC)::CreER) (Ralf Adams)

This allele is great, and quite effective at inducing recombination following a single i.p. injection of tamoxifen (postnatally or embryonically). Be aware that the minimal promoter used in the Tg(Cdh5::Cre(Speck)) line is not near where the Adams lab inserted CreER (if you're interested I can supply more fine details). Our gene-specific primers delineate between these two alleles, and they cannot be interchanged.

We have not used the Iruela-Arispe Cdh5-CreERT2 (Monvoisin et al., Dev Dyn, 2006) and cannot comment on its efficacy.

Below is a ventral view of E8.5 embryo from a cross between a (Cdh5-PAC-CreER) male and a R26-tdTomato/tdTomato (ai14/ai14) female, following tamoxifen administration at E6.5.