Figure 8. Fluorescence in situ hybridization detection of nuclear foci formation.

(A) Frozen muscle sections from CAG₀, CAG₂₃ and CAG₂₀₀ mice were hybridized with a Cy3-(CTG)₁₃ probe (red). The nuclei were counterstained with DAPI (blue). Merged images of red and blue signals are shown. Nuclear foci (arrows) are only detected in CAG₂₀₀ sections. (B) C2C12 cells transfected with pEGFP-CAG₀/₅₈/₂₀₀ and pEGFP-CTG₂₀₀ were hybridized with Cy3-(CTG)₁₃ and Cy3-(CAG)₁₃ probes, respectively. Distribution of endogenous MBNL proteins was visualized by immunostaining with an anti-MBNL antibody and a FITC-conjugated secondary antibody (green). Merged images showing superimposition of red and green signals (yellow) demonstrate that MBNL proteins are colocalized with expanded CAG and CUG repeats. Scale bars, 10 µm.