Deregulation of the Protocadherin Gene FAT1 Alters Muscle Shapes: Implications for the Pathogenesis of Facioscapulohumeral Dystrophy
Figure 6
Ablation of Fat1 in premigratory myoblasts using Pax3-cre partially reproduces the muscle migration/shape abnormalities of the constitutive knockout.
(A) Skeletal muscle cells were visualized at E12.5 in WT, Fat1ΔTM/ΔTM, Fat1Fln/Fln, and Fat1Fln/Fln; Pax3cre/+ embryos, owing to the MLC3F-2E transgene by performing X-gal staining, after clearing in 100% glycerol. The upper panels show micrographs of the forelimb area, and indicate the positions at which higher magnification pictures shown in the two lower panels were taken. (B, C) The phenotype was quantified in WT, Fat1ΔTM/ΔTM, Fat1Fln/Fln, and Fat1Fln/Fln; Pax3cre/+ as well as in the control genotypes in Fat1ΔTM/+, Fat1Fln/+ and Fat1Fln/+; Pax3cre/+ and Pax3cre/+ in two different manners: (B) by counting the number of dispersed myocytes found in the elbow area (orange dotted lines in the lower panels in (A)), (C) by measuring the area occupied by the ectopically positioned muscle (or myocyte cluster) that appears inserted between (red dotted line in middle panels). All data from a given genotype are plotted on a vertical line. Overlapping dots were arbitrarily moved away from the vertical lines to allow showing all results distinctly. In both cases, the Fat1ΔTM/ΔTM, Fat1Fln/Fln, and Fat1Fln/Fln; Pax3cre/+ groups were each significantly different from the control genotypes (WT, Fat1Fln/+, and Fat1Fln/+; Pax3cre/+ respectively, t-test, p values indicated), and were significantly different from each other (Fat1ΔTM/ΔTM from Fat1Fln/Fln, and from Fat1Fln/Fln; Pax3cre/+, but also Fat1Fln/Fln from Fat1Fln/Fln;Pax3cre/+, t-test, p values indicated).