Fig. 5

DUX4c is co-detected with MYOD, a myogenic regeneration marker. The FSHD muscle sections were treated and analyzed as in Fig. 3 with immunodetection of MYOD (green), DUX4c (red) and laminin-α2 (purple), observed by confocal microscopy. (Upper panel) A muscle section area with 3D reconstruction of two magnified regions. (Bottom panels) (Box 1) A muscle fiber tip with large nuclei surrounded by a MYOD staining with a partial DUX4c co-detection. Nuclear MYOD dots were also observed. Arrows point to the DUX4c labeling that is not co-localized with laminin-α2, supporting a cytoplasmic location. The triangle points to two dots, a DUX4c signal next to a MYOD one, at a nucleus periphery, without intense laminin-α2 staining. In contrast the area pointed with § shows co-detection of strong DUX4c and laminin-α2 signals between two nuclei. The arrowhead points to a DUX4c staining between two close nuclei (2 different focal depths using a 0.25-μm step in the Z axis, 18 images in total). (Box 2) MYOD detection in two close nuclei that belong to two distinct myofibers (separated by their respective laminin-α2 staining). The right one also presents a clear DUX4c nuclear signal. The arrowhead points to a partial nuclear MYOD/DUX4c co-detection. In addition, MYOD staining is observed around the nuclei and as a line just under the lamina of the right myofiber. DUX4c also shows similar staining in line with partial co-detection with MYOD. The image corresponds to a 0.25-µm section of the total 4.25 µm section depth