Deregulation of the Protocadherin Gene FAT1 Alters Muscle Shapes: Implications for the Pathogenesis of Facioscapulohumeral Dystrophy
Figure 7
Fat1 expression at late stages of muscle differentiation.
(A) Fat1 expression was visualized in E13.5 embryos or in neonate (P0) muscle by β-galactosidase staining or by in situ hybridization with a Fat1 3′UTR RNA probe. (B–D) Immunolocalization of FAT1 (anti-FAT1-ICD from [35], green) was performed in E12.5 mouse embryo (C), and on adult (B, D) muscle fibers on longitudinal muscle cryosections from wild type (B, C1–3, D1,4), from Fat1ΔTM/ΔTM embryos (C4–6), and from Fat1LacZ/LacZ (D2–3, D5–6) mice, combined with either antibodies against alpha-actinin (red, B5), DHPR (Cacna1s) (red, B2,3), or RyR (red, B4), or with Phalloidin (red, C, D). In D, Green channel images (FAT1) were first captured with either identical exposure time between wild type and mutants (D1,4 and D2,5, 421 ms), or with longer exposure time (D3,6, 2222 ms). This indicates that the epitope detected by the anti-FAT1-ICD antibody (from ref [35]) is present in reduced but detectable amounts in Fat1LacZ/LacZ muscles. This observation was made when Fat1LacZ/LacZ mice (n = 2 at P0; and n = 3 at adult stages) displayed severe muscle defects at the stage of dissection, indicating that levels of FAT1 protein inversely correlate with phenotype severity. Scale bars: (B–D) 4 µm, (C) 6 µm.