Transgenic Cre expression mice for generation of erythroid-specific gene alterations

Transgenic mice that express Cre recombinase in erythroid cell lineages were developed so that genes affecting erythropoiesis/hematopoiesis may be altered without necessarily affecting fetus viability. A micro-LCR cassette-beta-globin promoter-Cre recombinase gene (microLCR-betapr-Cre) construct was synthesized and used to generate transgenic mice. Concurrently, we produced mice containing a microLCR-loxP-flanked beta sickle gene (microLCR-loxP-beta(S)-loxP) construct. microLCR-betapr-Cre mice with intact transgenes in variable copy number were identified. Cre expression was assessed by RNAse protection and RT-PCR. Cre function was ascertained by breeding to microLCR-loxP-beta(S)-loxP mice. We demonstrate that beta(S) expression was not detected in the blood of bigenics, but the gene was present in nonerythroid cells. Thus, excision of the loxP-flanked beta(S) gene was restricted to erythroid cell lineages.