Split-Cre Complementation Indicates Coincident Activity of Different Genes In Vivo

Abstract

Cre/LoxP recombination is the gold standard for conditional gene regulation in mice in vivo. However, promoters driving the expression of Cre recombinase are often active in a wide range of cell types and therefore unsuited to target more specific subsets of cells. To overcome this limitation, we designed inactive “split-Cre” fragments that regain Cre activity when overlapping co-expression is controlled by two different promoters. Using transgenic mice and virus-mediated expression of split-Cre, we show that efficient reporter gene activation is achieved in vivo. In the brain of transgenic mice, we genetically defined a subgroup of glial progenitor cells in which the Plp1- and the Gfap-promoter are simultaneously active, giving rise to both astrocytes and NG2-positive glia. Similarly, a subset of interneurons was labelled after viral transfection using Gad67- and Cck1 promoters to express split-Cre. Thus, split-Cre mediated genomic recombination constitutes a powerful spatial and temporal coincidence detector for in vivo targeting.

Very long-term memories may be stored in the pattern of holes in the perineuronal net

“…An interesting variation on the above scheme would be to replace the DNA binding and transcriptional activation domains by complementary fragments of Cre recombinase (55,65); therefore, coincidence of high [Ca 2+ ] and light would reconstitute functional Cre and trigger excision of loxP-stop-loxP cassettes. The irreversibility of both of these steps would probably increase sensitivity at the potential cost of higher background and poorer temporal specificity.…”

Cre Recombinase

“…A subsequent study implemented the same Cre fragments, but fused them to the self-associating coiled-coil region from yeast GCN4 and expressed the two fragments under different promoters (112). The fragments spontaneously assemble in vivo to form an active enzyme, but with a more complex level of regulation than is possible using Cre expressed from a single promoter.…”

Genetic mouse models for skin research: Strategies and resources

“…Another example is the split-Cre system (Hirrlinger et al, 2009a;Hirrlinger et al, 2009b), in which inactive Cre fragments are expressed under the control of two different promoters and Cre activity is only attained by overlapping expression. These and other advancements will allow more sophisticated genetic analysis of cell lineage, which is particularly important for a better understanding of the complex stem cell populations of the skin.…”