C57BL/6-Ormdl1^em1Rlp/J

Stock number: 034646
Product name: Ormdl1 KO
Research areas: Neurobiology Research

Description

Ormdl1 KO mice carry a CRISPR/Cas9 generated 13 bp deletion in exon 2 resulting in premature termination of sequence. This strain useful when studying sphingolipid metabolism and myelination defects.

Detailed description

CRISPR/cas9 endonuclease mediated genome editing of the ORM1-like 1 (S. cerevisiae) (Ormdl1) gene was used to introduce a 13 bp deletion in exon 2. This mutation results in a frameshift and premature termination that eliminates more than 80% of the native protein coding sequence. ORMDL proteins (ORMDL1, 2 and 3) are small transmembrane endoplasmic reticulum proteins involved in feedback inhibition of the de novo synthesis pathway of sphingolipids by inhibiting serine palmitoyltransferase in response to elevated ceramide levels. Sphingolipids are a major class of bioactive lipids that are constituents of membranes in eukaryotes and are involved in various cellular functions such as growth regulation, apoptosis and signal transduction. Defects in sphingolipid metabolism can lead to elevated levels of sphingolipid metabolites, severe myelination defects and neurologic abnormalities. Elevated levels of sphingolipids are associated with diseases such as diabetes, various cancers and Alzheimer's disease.

Mice that are homozygous for this Ormdl1 KO allele are viable and fertile. Ormdl1 KO mice contain brain levels of 2 sphingolipid biosynthetic pathway intermediates, dihydrosphingosine and dihydroceramide, as well as levels of ceramide and sphingosine bioactive metabolites what are similar to those seen in WT mice.

When bred to Ormdl2 KO (Stock No. 034645), Ormdl1/2 double KO mice have brain levels of dihydrosphingosine, dihydroceramide, ceramide and sphingosine that are similar to WT mice.

When Ormdl3 KO mice are bred to Ormdl1 KO mice (Stock No. 034646), Ormdl1/3 double KO mice have brain levels of sphingolipid species dihydrosphingosine, dihydroceramide, ceramide and sphingosine significantly higher than in the Ormdl3 KO mice alone. These mice weigh significantly less than each single mutant line and less than Ormdl1/2 double KO mice and Ormdl2/3 double KO mice at 8 weeks of age. They also exhibit abnormal sciatic nerve morphology with lower frequency of myelinated axons and higher frequency of redundant myelin "outfoldings".

Ormdl1/2/3 triple KO mice are apparently embryonic lethal.

Development

Guide RNA and Cas9 was used to introduce a 13 bp deletion in exon 2 of the ORM1-like 1 (S. cerevisiae) (Ormdl1) gene. This mutation results in a frameshift and premature termination. It is unknown if any potential off-target sites are present. The sgRNA and the cas9 nuclease were introduced into the cytoplasm of C57BL/6NHsd-derived fertilized eggs with well recognized pronuclei. Correctly targeted embryos were transferred to pseudopregnant females. Ormdl1 KO pups were identified by sequencing and were further bred to C57BL/6NHsd mice to develop the colony. Upon arrival, sperm was cryopreserved. To establish our live colony, an aliquot of frozen sperm was used to fertilize C57BL/6J (Stock No. 000664) oocytes.

Allele

Symbol: Ormdl1^em1Rlp
Name: endonuclease-mediated mutation 1, Richard L Proia
MGI accession ID: MGI:6382069
Generation method: Endonuclease-mediated
Attributes: Null/Knockout
Marker symbol: Ormdl1
Marker name: ORM1-like 1 (S. cerevisiae)
Marker synonyms: C730042F17Rik
Chromosome: 1
Strain of origin: C57BL/6NHsd
Molecular note: CRISPR/Cas9 genome editing is use to introduce a 13 bp deletion in exon 2 of the gene. This mutation results in a frameshift and premature termination that eliminates more than 80% of the native protein coding sequence.