Figure 5.

Dystrophin-deficient satellite cells display impaired mitotic spindle orientation and loss of apicobasal division. (a) Representative pictures (n > 50 pictures) of immunostaining for phospho-Aurora kinase (p-Aurk; green), Pax7 (red), and DAPI (blue) of cultured myofibers from WT mice at 36 h. (b) Representative images (n > 20 pictures) of abnormal mitotic events of cultured myofibers from mdx mice at 36 h immunostained for p-Aurk (green), Pax7 (red), and DAPI (blue). (a,b) Mitotic centrosomes (arrowheads) are stained with anti-p-Aurk antibody in prophase and metaphase cells. (c) Proportion of mitotic satellite cells on cultured myofibers from WT and mdx mice at 36 h. (d) Quantification of abnormal, versus planar, and apicobasal orientated mitotic spindles in satellite cells on myofibers from WT and mdx mice after 36 h of culture. (c,d) n = 3 WT mice and n = 4 mdx mice, approximately 100 cells total per condition. (e) Example of immunostaining (n = 10 pictures) for Dmd rod domain (green), itga7 (red), p-Aurk (white) and DAPI (blue) in a mitotic satellite cell undergoing an apicobasal division. (f) Examples of mitotic satellite cells (n > 10 pictures) from immunostaining for itga7 (green), p-Aurk (red), and DAPI (blue) of cultured myofiber from Mark2^−/− mice at 36 h. n = 3 mice. (g) Quantification of abnormal, versus planar, and apicobasal orientated mitotic spindles in satellite cells on myofibers from WT and Mark2^−/− mice after 36 h of culture. n = 3 mice, >20 fibers counted per condition. (c,d,g) Error bars represent means ± SEM. *P < 0.05, **P < 0.01, ***P < 0.005. Statistical significance was calculated by Student’s t test. Scale bars, 5 μm.