C57BL/6-Cbx2^em1Rek/Mmjax

Stock number: 032257
Product name: CBX2^13KRA
Research areas: Developmental Biology Research, Internal/Organ Research

Description

CBX2^13KRA knock-in mice contain a substitution of 13 alanine codons in place of lysine or arginine codons in the compaction region of the CBX2 (chromobox 2, polycomb complex) protein resulting in anterior to posterior transformation of the axial skeleton.

Detailed description

Cbx2 (chromobox 2, polycomb complex) encodes a component of the Polycomb Repressive Complex 1 and contains a compaction region involved in bridging adjacent nucleosomes. The CBX2^13KRA mutation substitutes 13 alanine codons in place of lysine or arginine codons in the compaction region. Mice homozygous for the mutation are viable. Disruption of the compaction region results in posteriorization across the vertebral column with C7-to-T1, T1-to-T2, T7-toT8, T13 to-L1 and L6-toS1 transformations. Mice exhibit an increased incidence of C7 rib anlage. Unlike mice deficient in Cbx2, the CBX2^13KRA/13KRA mice do not exhibit postnatal lethality, reduced body weight or sex reversal. This strain may be useful in studies of axial body patterning and histone modification.

Development

CRISPR/cas9 endonuclease-mediated genome editing was used to insert 13 alanine codons in place of lysine or arginine codons between amino acids 132 to 240 of CBX2 (chromobox 2, polycomb complex). The corresponding sequence in exon 5 of the Cbx2 gene on chromosome 11 encodes a part of the compaction region and disrupts the ability of the CBX2 protein to compact nucleosomes. Single guide RNA and Cas9 endonuclease were introduced into C57BL/6-derived fertilized eggs by pronuclear injection. Embryos were transferred to pseudopregnant females, and correctly targeted pups were bred to C57BL/6 inbred mice for germline transmission. The colony was crossed to C57BL/6J mice for at least eight generations by the donating investigator. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J oocytes.

Allele

Symbol: Cbx2^em1Rek
Name: endonuclease-mediated mutation 1, Robert E Kingston
MGI accession ID: MGI:5910878
Generation method: Endonuclease-mediated
Attributes: Hypomorph
Synonyms: Cbx2^13KRA
Marker symbol: Cbx2
Marker name: chromobox 2
Marker synonyms: CDCA6; M33; SRXY5
Chromosome: 11
Strain of origin: C57BL/6
Molecular note: A portion of the part of the gene coding for the compaction region, one of the active domains of the protein, was replaced with synthetic sequence where 13 selected lysine and arginine codons had been changed to alanine codons. This was done through CRISPR/Cas9 endonuclease-assisted homologous recombination where the transgene vector, two sgRNAs and Cas9 mRNA were injected into C57BL/6 zygotes. The allele codes for a protein with redsuced activity.