Male germline recombination of a conditional allele by the widely used Dermo1‐cre (Twist2‐cre) transgene

Abstract

Conditional gene knockout using the Cre/loxP system is instrumental in advancing our understanding of the function of genes in a wide range of disciplines. It is becoming increasingly apparent in the literature that some Cre transgenes mediated recombination occurs in unexpected tissues. Dermo1-Cre (Twist2-Cre) has been widely used to target skeletal lineage cells as well as other mesoderm-derived cells. Here we report that Dermo1-Cre exhibits spontaneous male germline recombination activity leading to a Cre-mediated recombination of a floxed Ptk2 (Protein tyrosine kinase 2, also known as Fak [Focal adhesion kinase]) allele but not a floxed Rb1cc1 (RB1 inducible coiled-coil 1, also known as Fip200 [FAK-family Interacting Protein of 200 kDa]) allele at high frequency. This ectopic germline activity of Dermo1-Cre occurred in all or none manner in a given litter. We demonstrated that the occurrence of germline recombination activity of Dermo1-Cre transgene can be avoided by using female mice as parental Dermo1-Cre carriers.

Sites of Cre-recombinase activity in mouse lines targeting skeletal cells

“…Tables 1–6 list the Cre lines discussed and include references of documents describing Cre activity in bone and off‐target sites, and original articles reporting the lines (knock‐in–based Cre lines in these tables are labeled with an asterisk). ( 22‐213 )…”

Cre-Recombinase Dependent Germline Deletion of a Conditional Allele in the Rgs9cre Mouse Line

“…Although Cre- Lox P conditional knockout mice have been transformative in neuroscience research, significant limitations exist (Schmidt-Supprian and Rajewsky, 2007 ; Harno et al, 2013 ). One such limitation is the potential for germline recombination of conditional alleles due to transient Cre expression in the germline (for a detailed description see, Song and Palmiter, 2018 ), a phenomenon documented with increasing frequency in the literature (Rempe et al, 2006 ; Zeller et al, 2008 ; Friedel et al, 2011 ; Tsai et al, 2012 ; Kobayashi and Hensch, 2013 ; Zhang et al, 2013 ; He et al, 2017 ; Song and Palmiter, 2018 ). The current report describes germline recombination in the Rgs9cre line (Dang et al, 2006 ), which has been widely used to manipulate medium spiny neurons in the striatum.…”

The Wnt1‐Cre2 transgene is active in the male germline

“…These include damage due to injection, toxicity caused by Cre expression, variable expression, methylationinduced silencing over time, and ectopic expression including in the male and female germlines (Clark, Dinsmore, & Soriano, 2020;Song & Palmiter, 2018). Indeed, Wnt1-Cre2 joins several other transgenic Cre lines recently found to have ectopic male germline activity (de Lange, Halabi, Beyer, & Sigmund, 2008;He et al, 2017;McLeod, Cuic, Chiam, Lau, & Turner, 2020). The ease of transgenesis has historically been viewed as a large enough advantage to overcome the many drawbacks and justify use of the technique.…”