B6C3-Sms^em2Lutzy/J

Stock number: 033707
Product name: B6C3F1.Sms^G56S
Research areas: Developmental Biology Research, Neurobiology Research, Reproductive Biology Research, Research Tools

Description

Sms^G56S is a CRISPR/Cas9-generated mutant of the Sms gene harboring the G56S point mutation. This strain may be useful in studies related to X-linked Snyder-Robinson Syndrome mental retardation. Mice on this C57BL/6J-C3H/HeJ mixed background show improved viability over the original C57BL/6J genetic background line (Stock No. 031170).

Detailed description

The spermine synthase gene (Sms) encodes an enzyme involved in biosynthesis of polyamines. Mutations in this gene have been associated with X-linked Snyder-Robinson Syndrome mental retardation.

To create the Sms^G56S allele, CRISPR/Cas9 endonuclease-mediated genome editing was used to introduce a glycine to serine mutation at amino acid 56 (G56S) to the X-linked mouse Sms locus. The mutation was originally created on a C57BL/6J genetic background (see Stock No. 031170), but carrier males showed poor viability and were produced at reduced frequency; only ~6-8% hemizygous male pups were produced from heterozygous female x wildtype male crosses.

Mice carrying the mutation on this C57BL/6J x C3H/HeJ hybrid background (B6C3F1.Sms^G56S) show improved survival over the original C57BL/6J genetic background line (Stock No. 031170). B6C3F1.Sms^G56Sheterozygous females (Stock No. 033707) bred with B6C3F1/J (Stock No. 100010) produce pups at anticipated Mendelian ratios and with good viability.

Development

This Sms^G56S mutation was originally created on a C57BL/6J genetic background using CRISPR/Cas9 endonuclease-mediated genome editing (see Stock No. 031170). Specifically, the spermine synthase locus (Sms) on chromosome X was targeted with single guide RNAs designed to substitute the GGC wild type glycine56 codon with a TCC Serine56 codon (G56S). The sgRNAs, an oligonucleotide sequence containing the G56S mutation, and Cas9 endonuclease were electroporated into the cytoplasm of single cell C57BL/6J-derived zygotes containing well recognized pronuclei. Embryos were transferred to pseudopregnant females, and correctly targeted pups (identified by DNA sequencing) were bred to C57BL/6J inbred mice for germline transmission. Mice derived from founder 5525 (GET2418) were further bred to C57BL/6J inbred mice for 2 generations to develop a colony. As a consequence of these nucleotide changes the mutant Sms^G56S allele contains an EcoRI restriction enzyme site that is absent in the wildtype Sms allele.

To produce animals on this hybrid genetic background, animals from the C57BL/6J background strain (Stock No. 031170) were intercrossed with C3H/HeJ animals (Stock No. 000659). The colony was thereafter maintained through crosses of heterozygous females with B6C3F1/J (Stock No. 100010) males at every generation.

Allele

Symbol: Sms^em2Lutzy
Name: endonuclease-mediated mutation 2, Cathy Lutz
MGI accession ID: MGI:6283829
Generation method: Endonuclease-mediated
Attributes: Not Applicable
Marker symbol: Sms
Marker name: spermine synthase
Marker synonyms: MRSR; MRXSSR; SpmST; SPMSY; SpS; SRS
Chromosome: X
Strain of origin: C57BL/6J
Molecular note: CRISPR/Cas9 genome editing is used to substitute the GGC wild type glycine56 codon with a TCC Serine56 codon (G56S). The mutation introduces a EcoRI restriction enzyme site.