B6;C-Nrn1^tm1.1Ndiv/J

Stock number: 034075
Product name: cpg15^flox
Research areas: Developmental Biology Research, Neurobiology Research, Research Tools

Description

Cpg15^flox mice possess loxP sites flanking exons 2-3, encoding the entire coding sequence of the neuritin 1 (Nrn1) gene. These floxed mice are useful when studying the development and growth of differentiating neurons.

Detailed description

Cpg15^flox mice possess loxP sites flanking exons 2-3, encoding the entire coding sequence of the neuritin 1 (Nrn1) gene. This gene, also known as CPG15, is expressed in neural progenitors, postmitotic-differentiating neurons during development, in differentiated neurons in the adult, as well as in some non-neuronal tissues such as liver and immune cells. CPG15 promotes neuronal survival during early development and synapse stabilization and process outgrowth in primary hippocampal and cortical neurons. Mice that are homozygous for this floxed allele are viable and fertile. When bred to mice that express tissue-specific Cre recombinase, resulting offspring will have exons 2-3 deleted in the Cre-expressing tissues.

For example, when bred to the mice with EIIa-cre mice (Stock No. 003724) with germ line cre expression, the resulting KO mice exhibit delayed developmental maturation of axonal and dendritic arbors. Synaptic maturation is also delayed, and 30% of dendritic spines initially lack functional synaptic contacts. Once circuits develop, spine maintenance is compromised in the adult, leading to a gradual attrition in spine numbers. Mice have poor learning behaviors.

Development

The Cpg15^flox targeting vector was designed to insert a loxP site upstream of exon 2 and a loxP- and frt-flanked neomycin selection cassette downstream of exon 3 of the neuritin 1 (Nrn1) gene. The construct was electroporated into C57BL6-derived embryonic stem (ES) cells and correctly targeted ES cells were injected into recipient BALB/c blastocysts. Chimeras were bred with C57BL/6 mice. Embryos from the resulting Cpg15^flox-neo/+ mice were injected with pOG-Flpe6 cRNA to remove the neo cassette. Cpg15^flox mice were bred with C57BL/6J mice for one generation by the donating lab (see SNP note below). Upon arrival at The Jackson Laboratory, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes (Stock No. 000664).



In 2019 a 48 SNP (single nucleotide polymorphism) panel analysis, with 43 markers covering all 19 chromosomes and the X chromosome, as well as 5 markers that distinguish between the C57BL/6J and C57BL/6N substrains, was performed on the rederived living colony at The Jackson Laboratory Repository. Many of the 43 markers throughout the genome were segregating with BALB/c from an unknown source.

Allele

Symbol: Nrn1^tm1.1Ndiv
Name: targeted mutation 1.1, Elly Nedivi
MGI accession ID: MGI:5307917
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); No functional change
Marker symbol: Nrn1
Marker name: neuritin 1
Marker synonyms: 0710008J23Rik; cpg15; dJ380B8.2; Nrn
Chromosome: 13
Strain of origin: C57BL/6
Molecular note: A loxP site was inserted upstream of exon 2 and a loxP and FRT flanked neo cassette was inserted downstream of exon 3 via homologous recombination. Flp mediated recombination removed the neo cassette leaving exons 2 and 3 floxed.