The “deletion” mouse was developed by GESC internal R&D with Mouse Genetics Core (MGC, link https://mgc.wustl.edu/ ) to improve efficiency in creating mouse models for tissue specific overexpression from the ROSA26 locus.
There are frequent requests to create mice by inserting into the ROSA26 safe harbor site a cassette of the following configuration to overexpress an open reading frame (ORF) only in Cre recombinase positive cells in the body:
![](https://geneediting.wustl.edu/files/2022/02/DM1.png)
Except for the ORF to be expressed, the rest of the cassette remains the same in different models and yet is 3 kb long. The “deletion” mouse has CAG promoter, floxed 3x SV40 pA and BGH pA but no cDNA.
An example of the original donor design used previously
![](https://geneediting.wustl.edu/files/2022/02/DM2.png)
The total insert is 4.7 kb for a cDNA of 1.8 kb. Larger insertions tend to be less efficiently incorporated into the genome in zygotes, even with the assistance of CRISPR.
Insertion of a large cassette by TALENs or CRISPR![]()
![](https://geneediting.wustl.edu/files/2022/02/DM3.png)
![](https://geneediting.wustl.edu/files/2022/02/DM4.png)
“Deletion” mouse created by removing cDNA from an existing model
![](https://geneediting.wustl.edu/files/2022/02/DM5.png)
Unique, new gRNA site for inserting other ORFs between floxed stop and
polyA signal
![](https://geneediting.wustl.edu/files/2022/02/DM6.png)
Only coding sequences have to be inserted in the “Deletion” mouse
![](https://geneediting.wustl.edu/files/2022/02/DM7.png)
In conjunction of rAAV donors, creating a new model for conditional overexpression can be achieved by one or two electroporation sessions.
Large knockin by rAAV donor transduction vs. donor plasmid microinjection
![](https://geneediting.wustl.edu/files/2022/02/Picture1.png)
Even larger insertions can be delivered efficiently by using two rAAVs
![](https://geneediting.wustl.edu/files/2022/02/DM9.png)