Mice that are homozygous null for the Cxcr4 gene die perinatally, with ~30% dying by embryonic day 18.5. Viable embryos are slightly smaller than wild type mice and exhibit vascular congestion in the kidneys, interstitial hemorrhages, and abnormalities in bone marrow and cerebellum. Homozygote embryos also show reduced B-lymphopoiesis, reduced myelopoiesis in fetal liver and an absence of myelopoiesis in bone marrow. Histological examination reveals a distorted architecture in the tissues if the cerebellum, featuring an attenuated external granule cell layer and an ectopic placement of Purkinje cells.
Cxcr4 encodes a receptor commonly called CXCR4, the ligand of which is the chemokine stromal cell-derived factor 1 (SDF-1), an important regulator of hematopoietic cell development, migration and proliferation. CXCR4 also functions as a coreceptor for the entry of T-tropic strains of HIV-1 into CD4+ T cells.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. This is the case for the strain above. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
