Jax Stock # 033318
These Sall1ncre:Cx3cr1ccre (CX/Sall1) mice use a binary transgenic cre approach to dissect functions of central nervous system (CNS) macrophage subpopulations.
This dual-recombinase strain enables microglia-specific Cre activity by reconstituting functional Cre recombinase from two complementary fragments. The Sall1<sup>ncre</sup> allele expresses the N-terminal fragment of Cre (NCre, 40 aa) under the Sall1 promoter, which marks microglia and selected mesenchymal and CNS cells. The Cx3cr1<sup>ccre</sup> allele expresses the C-terminal Cre fragment (CCre, 283 aa) under the macrophage-lineage Cx3cr1 promoter. Each fragment alone is inactive but contains leucine-zipper domains that mediate dimerization.
Co-expression of NCre and CCre in parenchymal microglia restores full Cre recombinase activity, enabling selective deletion of floxed alleles in microglia while preserving endogenous gene expression via 2A self-cleaving peptides. Double homozygotes are viable and fertile, and recombination occurs specifically in microglial cells of the CNS.
