These Sos1E846K mice exhibit phenotypes consistent with several features of Noonan syndrome including: cardiac hypertrophy, short stature, triangular faces and blunt snouts, splenomegaly, and hematologic disorders. Most homozygous embryos die due to cardiac defects.
Benjamin Neel, NYU School of Medicine
SOS1 (son of sevenless homolog 1) encodes a RAS and RAC guanine nucleotide exchange factor (GEF) and is involved regulation of the RAS/ERK/MAPK pathway. Mutations in this gene are associated with Noonan syndrome (NS), an autosomal dominant disorder characterized by with congenital heart disease, short stature, facial abnormalities and myeloproliferative disease. 10-15% of NS patients have mutations in Sos1. The E846K allele is a missense mutation that causes a conformational change resulting in constitutive activation of the RAS/MAPK pathway.
Most homozygous embryos die between E10.5 and the neonatal stage from multiple cardiac defects including atrial/ventricular septal defects, aortic valvular stenosis, ventricular hypertrophy and pericardial effusions. Surviving homozygous mice do not live beyond 10 months of age.
Heterozygotes exhibit left ventricular cardiac hypertrophy, short stature, shortened skull length with triangular faces and blunt snouts, splenomegaly, and increased numbers of neutrophils and leukocytes.
The targeting vector is designed as a unidirectional Cre-mediated recombination system. The vector contains a wild-type loxP (wloxP) site upstream of exon 16, a mutant loxP (mloxP) site downstream of exon 16, an inverted exon 16 with the amino acid substitution E846K, followed by wloxP and mloxP sites and an FRT-flanked neomycin cassette. The mloxP sites preferentially recombine with each other, as do the wloxP sites. The E846K mutation results in a glutamic acid to lysine change at position 846. The construct was electroporated into 129S4/SvJae –derived J1 embryonic stem (ES) cells. Correctly targeted ES cells were injected into recipient blastocysts. The resulting chimeric animals were crossed to B6.Cg-Tg(ACTFLPe)9205Dym/J to remove the neomycin cassette, followed by a cross to unspecified EIIA-cre mice on a C57BL/6 background .
Following Cre exposure, the inverted exon 16 (with the E846K mutation) moved into the correct orientation and the endogenous exon 16 was removed.
Heterozygous mice were mated and offspring lacking the Cre transgene were crossed to C57BL/6 mice for at least 10 generations. Upon arrival, mice were bred to C57BL/6J for at least 1 generation to establish the colony.
|Allele Name||targeted mutation 1.2, Raju Kucherlapati|
|Allele Type||Targeted (Humanized sequence)|
|Allele Synonym(s)||Sos1E846K; Sos1E846K|
|Gene Symbol and Name||Sos1, SOS Ras/Rac guanine nucleotide exchange factor 1|
|Strain of Origin||129S4/SvJae|
|Molecular Note||A wloxP site was inserted upstream of exon 16. An inverted segment that contained an mloxP flanked, modified exon 16 with an upstream wloxP site and an FRT-flanked neo cassette was inserted downstream of exon 16. The modified exon 16 contains an C to T transition that results in an glutamic acid to lysine at position 846 (E486K, equivalent to a mutation found in Noonan syndrome (NS) patients). Flp-mediated recombination removed the neo cassette. Cre-mediated recombination rearranged the modified exon 16 into correct orientation and removed the endogenous exon 16.|
While maintaining a live colony, these mice are bred as heterozygotes. Most homozygous embryos die due to cardiac defects.
When using the Sos1E846K mouse strain in a publication, please cite the originating article(s) and include MMRRC stock #37588 in your Materials and Methods section.