B6.SJL(C)-Slc25a13^hspn/Kjn

Stock number: 005679
Product name: hyperspin
Research areas: Developmental Biology Research, Sensorineural Research

Description

This 123.6 kb intragenic deletion appears to include a regulatory sequence that controls Dlx5 expression at least in the otocyst so this mutant provides a model of split-hand/foot malformation 1 (SHFM1) without craniofacial defects and a model with which to dissect the regulation of the genomic region that includes Dlx5 and Slc25a13.

Detailed description

The hyperspin mutation is a spontaneous 123.6 kb deletion that begins in intron 3 of Slc25a13 and ends in exon 17, an interval that includes an enhancer of Dlx5. This deletion includes the putative enhancer elements hs2313 and hs1642, and overlaps the regions corresponding to the predicted intervals of split-hand/foot malformation (SHFM) and split-hand/foot malformation with hearing loss (SHFM & HL) sub-regions of the SHFM1 locus, but not the split-hand/foot malformation with hearing loss and craniofacial abnormalities (SHFM & HL & CF) sub-region. Hyperspin homozygotes exhibit the phenotypes indicative of a vestibular defect, rapid circling, head shaking, and failure to orient in water, but null alleles in Slc25a13 have not been found to cause vestibular defects. At 4 to 5 weeks of age homozygotes were found to be deaf by ABR analysis. At 5 weeks of age the inner ears of homozygotes are small and malformed, the cochlea has too few turns and appears swollen, and the three semicircular canals are absent, reduced, or malformed. At embryonic day 15.5 the endolymphatic duct and sac and the superior and posterior semicircular canals are missing, the cochlear duct is wider and has fewer coils than normal, and most homozygotes also lack the lateral semicircular canal and utricle. Scanning electron microscopy of the basal and middle turns of the cochlea at 4 weeks of age revealed only occasional missing hair bundles, but the apical turn had an additional forth and sometimes fifth row of outer hair cells and abnormal hair bundle orientations. Only approximately 30% of female and 50% of male hyperspin homozygotes survive to wean age. Hyperspin homozygotes have reduced otocyst expression but not branchial arch expression of Dlx5, a gene more than 600 kb away on Chromosome 6, and null alleles of Dlx5 have been found to cause perinatal death, dysmorphic inner ears and other craniofacial abnormalities. While hyperspin heterozygotes have a normal phenotype fewer than 10% of Slc25a13^hspn Dlx5⁺/Slc25a13⁺ Dlx5^{tm1(cre/ERT2)Zjh} transchromosomal heterozygotes survive to wean age, a more severe phenotype than that of hyperspin homozygotes and further proof of the presence of a Dlx5 modifier within the hyperspin deletion. These double heterozygotes display circling and head bobbing, are deaf by ABR, and have malformed inner ears similar to that found in hyperspin homozygotes.

To identify the sequence within the hyperspin deletion that regulates Dlx5 otic expression, endonuclease-mediated deletions were generated of hs2313 in intron 14, hs1642 in intron 3, and intron 3 through 4. None of these caused the phenotype found in hyperspin homozygotes, even when Dlx5^{tm1(cre/ERT2)Zjh} transchromosomal heterozygotes were generated.

Development

The hyperspin deletion arose spontaneously in the CXJ1/SalkJ strain at The Jackson Laboratory and it was later determined that the mutation arose in SLJ/J-derived sequence. This mutation was moved onto the C57BL/6J background by repeated backcross-intercross breeding until generation N10 when sibling intercrossing of heterozygous females with homozygous males began. Embryos were cryopreserved from C57BL/6J females bred to homozygous males at generation N10F3.

Allele

Symbol: Slc25a13^hspn
Name: hyperspin
MGI accession ID: MGI:5514275
Generation method: Spontaneous
Attributes: Null/Knockout; Dominant negative
Marker symbol: Slc25a13
Marker name: solute carrier family 25 (mitochondrial carrier, adenine nucleotide translocator), member 13
Chromosome: 6
Strain of origin: SJL/J
Molecular note: The hyperspin mutation is a spontaneous 123.6 kb deletion of Chromosome 6: 5.86-6.66 Mb (GRCm38) that begins in intron 3 of Slc25a13 and ends in exon 17, an interval that includes an enhancer of Dlx5 and, in addition to creating a null allele of Slc25a13, diminishes otocyst expression of Dlx5.

Allele

MGI accession ID: MGI:101926
Marker symbol: Dlx5
Marker name: distal-less homeobox 5
Chromosome: 6