The 1.4 kb proximal mouse Selp promoter is replaced with the corresponding sequence of the human gene in this targeted knock-in line. This substitution eliminates most, but not all, of the responsiveness of the mouse Selp gene to TNF and LPS.
Rodger McEver, Oklahoma Medical Research Foundation
In humans and mice, megakaryocytes/platelets and endothelial cells constitutively synthesize P-selectin (SELP) and mobilize it to the plasma membrane to mediate leukocyte rolling during inflammation. Tumor necrosis factor (TNF), interleukin 1 beta (IL1B), and lipopolysaccharide (LPS) markedly increase P-selectin mRNA in mice but decrease P-selectin mRNA in humans.
In this targeted knock-in strain, the 1.4 kb proximal mouse Selp promoter is replaced with the corresponding sequence of the human gene. This substitution eliminates most, but not all, of the responsiveness of the mouse Selp gene to TNF and LPS.
Anti-murine SELP monoclonal antibody binds to thrombin-activated but not resting platelets of homozygous SelpKI mice, consistent with redistribution of P-selectin from α-granules to the plasma membrane. Activated platelets derived from homozygous mice express approximately 1.5-fold more SELP than activated wildtype platelets. Peritoneal macrophages from these mice also express more SELP. Basal SELP mRNA levels in the heart, lung, and liver are 2- to 6-fold higher.
Wildtype mice injected intravenously with TNF or LPS increase expression of SELP mRNA by 10- to 100-fold. Homozygous knock-in mice up-regulated P-selectin mRNA only 2- to 7-fold. Consistent with higher basal expression, leukocytes rolled more slowly on P-selectin in trauma-stimulated venules of homozygous knock-in mice.
A 1.4 kb promoter segment just 5' of the mouse Selp translation start site was replaced with the corresponding 1.4-kb human-derived sequence and a loxP-flanked hygromycin cassette was inserted into intron 1. The linearized targeting vector was electroporated into 129S1/Sv-p+Tyr+Kitl+-derived CJ7 embryonic stem (ES) cells. After drug selection, the loxP-flanked hygromycin cassette was removed by transient in vitro expression of cre recombinase. Resultant chimeric offspring were bred with C57BL/6J mice for more than 10 generations by the donating lab.
|Allele Name||targeted mutation 1.1, Rodger P McEver|
|Allele Type||Targeted (Humanized sequence)|
|Gene Symbol and Name||Selp, selectin, platelet|
|Strain of Origin||129S1/Sv-Oca2+ Tyr+ Kitl+|
|Molecular Note||A 1.4 kb promoter segment 5' of the translation start site is replaced with the corresponding 1.4-kb human-derived sequence. A loxP-flanked hygromycin cassette was inserted into intron 1. The loxP-flanked hygromycin cassette was removed by transient in vitro expression of Cre recombinase.|
Homozygous and heterozygous mice are viable and fertile.
When using the SelpKI mouse strain in a publication, please cite the originating article(s) and include JAX stock #029106 in your Materials and Methods section.