These Nrp1 knock-in mice exhibit postnatal lethality and display defasciculated and abnormally extended cranial and spinal nerves.
David D. Ginty, Harvard Medical School
Mice that are homozygous for the targeted mutation are viable, but experience fertility problems. Homozygous mice have increased incidence of postnatal lethality by 7 days of age. Mutant mice express normal levels of gene product of the variant protein that does not bind semaphorins and retains binding ability for VEGF. Homozygotes display axon guidance defects with little or no binding activity of semaphorin 3A or 3C to axons in the dorsal root entry zone. Cultured neurons isolated from mutant mice do not respond to semaphorin3A. Cranial and spinal neurons from E11.5 and E12.5 embryos are disorganized, defasciculated and have abnormal errant projections. This mutant mouse strain may be useful in studies of neural development and axonal guidance.
A targeting vector containing loxP site flanked selection cassette (neomycin resistance and herpes simplex virus thymidine kinase genes) and sequence encoding a 7 amino acid substitution in exon 2 was utilized in the construction of this mutant. The construct was electroporated into 129.1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6 blastocysts. The resulting chimeric animals were crossed to mice expressing Cre recombinase (BALB/c-Tg(CMV-cre)1Cgn/J Stock#3465), and then backcrossed to C57BL/6 for 6 generations
|Allele Name||targeted mutation 1, David D Ginty|
|Gene Symbol and Name||Nrp1, neuropilin 1|
|Promoter||Nrp1, neuropilin 1, mouse, laboratory|
|Strain of Origin||129P2/OlaHsd|
|Molecular Note||Exon 2 was replaced with a mutated exon 2 encoding 7 amino acid substitutions (H46E, S47A, S51A, E52R, K53D, D79K, R80E) in three regions of the amino-terminal CUB domain, and a loxP site flanked neomycin resistance gene cassette was inserted into intron 1. The neo cassette was removed through subsequent cre-mediated recombination. Mutation of these sites was shown to abolish Sema3 family binding but not VEGF binding. Immunohistochemistry showed that homozygotes express normal levels of protein.|
|Mutations Made By|| |
Dori (Dorothy) Reimert, Johns Hopkins University
This strain is maintained as a heterozygote. Homozygotes are viable but experience fertility problems.
When using the Npn-1Sema- KI mouse strain in a publication, please cite the originating article(s) and include JAX stock #005245 in your Materials and Methods section.