Methods: Craniofacial measurements, microCT, skeletal staining, histology, qPCR, and Northern and Western blotting were performed on late gestation (17.5 & 18.5dpc) wildtype and CP OVE1226b embryos.
Results: CP embryos exhibit micrognathia, tongue protrusion, U-shaped cleft, and rhizomelic shortening of the limbs. At 18.5dpc, CP and wildtype embryos showed differences for snout tip to eye (p=0.001) and snout tip to ear (p=0.018) measurements. Skeletal staining demonstrated reduced skeletal mineralization in CP embryos. Humerus bone mineral densities were less in CP embryos compared to wildtype at 17.5dpc (p <0.001) and 18.5dpc (p=0.01). qPCR showed 62-fold downregulation of expression of Col11a1 in CP compared to wildtype (p=0.007). Northern blotting revealed greatly reduced Col11a1transcripts for the CP mouse. Additionally, Western blotting showed decreased COL11A1 expression in CP embryos.
Conclusions: The OVE1226b CP mouse recapitulates phenotypic features seen in cho/cho (chrondrodysplasia) mice. The cho/cho mouse results from a single nucleotide deletion in the Col11a1 gene and the absence of COL11A1 protein; OVE1226b CP mice present with a comparable phenotype to cho/cho even when some COL11A1 is present. This demonstrates that reduction in COL11A1 is sufficient to interfere with normal fibrillogenesis. COL11A1 mutations in humans are associated with Stickler and Marshall syndromes, and some cases of Robin sequence. (Supported by NIH DE015180/AADR Student Research Fellowship)