Fig. 2

Skeletal muscle pathology and plectin expression in EBS-MD muscle. a Skeletal muscle sections from a healthy control and patients 1–3 were stained by hematoxylin and eosin. Note the rounding of muscle fibers with marked variation in fiber size, internalization and clustering of myonuclei, and increased amount of connective tissue in EBS-MD patient muscles. Scale bar: 50 μm. b Immunofluorescence microscopy of skeletal muscle sections from a healthy control and patients 1–3 using antibodies PN643, regognizing the N-terminal actin binding domain (aa 171–595), and GP-21, recognizing plectin’s C-terminus (aa 4367–4684 in exon 32). Nuclei were visualized using Dapi. Note the drastically reduced plectin staining intensity in muscle tissue from patients 2 and 3, as well as the completely absent staining in patient 1. Scale bar: 50 μm. c and d Immunoblotting of cell lysates prepared from patient 1 (c), patients 2 and 3 (d), and a healthy control. Antibodies used for detection are indicated. GAPDH was used as loading control. Note that plectin antibody GP-21 detects plectin’s C-terminal region (aa 4367–4684 in exon 32), whereas plectin antiserum #9 recognizes the N-terminal region (exons 9–12). While no plectin band could be detected in patient 1, markedly reduced but still recognizable plectin levels were observed in patient 2. Patient 3 had no expression of full-length plectin, while rodless plectin was still found