Safe Harbor Locus (Rosa26 and Polr2a)
Precise gene targeting at your choice of safe harbor locus.
A safe harbor locus is a place in the genome which allows for expression of an inserted transgene without the risk of affecting surrounding endogenous genes. Gene targeting at this type of locus gives you control of copy number while avoiding the undesirable effects of random insertion transgenics, namely undesirable position effects that can cause unstable phenotypes, gene silencing, or unexpected gene expression.
At ingenious, your transgene of choice can be delivered to a safe harbor locus in the mouse genome and be constitutively or inducibly overexpressed. We use both the classic Rosa26 locus, as well as Polr2a as an alternative locus for targeting. Polr2a has been shown to be a permissive locus in neuroscience1 and ingenious has applied this technology to other research fields for our clients. Targeting the Polr2a locus with your transgene may be of interest if you already have Rosa26 lines and would like to mate to another line in order to study two or more targeted transgenes at once, or if you need an alternative locus to Rosa26 for your research field.
With our well-validated gene targeting strategies combined with our pre-constructed targeting vector materials, ingenious can generate precisely targeted, custom transgenic mouse models with a variety of expression possibilities at reduced timelines and cost when compared to traditional targeted knockin models.
For more information, please contact us.
Designs options available using Rosa26 or Polr2a:
- Drive expression of a cDNA using a ubiquitous or tissue-specific promoter
- Conditional cDNA overexpression, which you control using tissue-specific Cre lines
- Drug-inducible overexpression, controlled by administering doxycycline
You may also be interested in: Mouse Rosa26 Locus
Why use safe harbor loci?
Safe harbor loci are used as places in the genome where the insertion of foreign DNA would not have unpredictable results. Unpredictable results could mean either unwanted effects on the health of the mouse, or unpredictable expression of the foreign DNA. Targeting foreign DNA into the Rosa26 locus for example seems to have essentially no effect on the mouse’s health. In addition, the DNA that is inserted will have a consistent expression pattern, which is not the case with random pronuclear injection transgenics. With pronuclear injection, the transgene can be inserted near another gene, and that gene’s promoter can influence the inserted DNA. Another aspect to consider is – targeting your transgene into a safe harbor locus means you’ll know your transgene will be there generation after generation, whereas randomly inserted trangenes may be lost over time. Using a safe harbor locus for targeted transgenic knockin can take away the uncertainty seen with pronuclear injection transgenics.
To learn more, see Understanding the Rosa26 Knock-in and Its Uses
References
1) Gee JM, Smith NA, Fernandez FR, Economo MN, Brunert D, Rothermel M, Morris SC, Talbot A, Palumbos S, Ichida JM, Shepherd JD, West PJ, Wachowiak M, Capecchi MR, Wilcox KS, White JA, Tvrdik P. 2014. Imaging activity in neurons and glia with a Polr2a-based and cre-dependent GCaMP5G-IRES-tdTomato reporter mouse. Neuron 83(5): 1058-72.
Notable Client Publications Using Rosa26
1) Kasatkina LA, Ma C, Matlashov ME, Vu T, Li M, Kaberniuk AA, Yao J, Verkhusha VV. 2022. Optogenetic manipulation and photoacoustic imaging using a near-infrared transgenic mouse model. Nat Commun 13(1): 2813.
2) Samant SA, Pillai VB, Gupta MP. 2021. Skeletal muscle-specific over-expression of the nuclear sirtuin SIRT6 blocks cancer-associated cachexia by regulating multiple targets. JCSM Rapid Commun 4(1): 40-56.
3) McCann JJ, Vasilevskaya IA, Poudel Neupane N, Shafi AA, McNair C, Dylgjeri E, Mandigo AC, Schiewer MJ, Schrecengost RS, Gallagher P, Stanek TJ, McMahon SB, Berman-Booty LD, Ostrander WF, Knudsen KE. 2020. USP22 functions as an oncogenic driver in prostate cancer by regulating cell proliferation and DNA repair. Cancer Res 80(3): 430-443.
