Figure 3.

AT-GAA Eliminated Autophagic Buildup in Vast Majority of Myofibers from KO Mice

Muscle biopsies were collected from age and sex-matched WT, untreated (KO), and AT-GAA-treated KO (KO-ERT) mice. Confocal microscopy images of single muscle fibers immunostained with lysosomal marker LAMP1 (red) and autophagosomal marker LC3 (green); nuclei are stained with Hoechst dye (blue). (A) Abundant dot-like LAMP1-positive structures (red) are seen in a fiber from a WT mouse; LC3-positive autophagosomes are barely detectable in control fibers (n = 60 from 3 mice). (B and C) Enlarged lysosomes (red) and autophagic buildup (the multicolored areas in the core of muscle fibers) are detected in virtually all myofibers from KO mice; the images show two neighboring fibers with autophagic buildup located in different focal planes; therefore, the buildup is seen in the left fiber in (B), and in the right fiber in (C) (n = 85 from 4 untreated KO mice). See also Video S1. (D–G) The 4 right panels show the representative images of myofibers from treated KO mice (n = 217 from 4 mice). Myofibers shown in (D), as well as the left fiber in (G), are considered normal; near normal fibers are shown in (E) and (F) (n = 182; ∼84% of normal or near normal fibers). The right fiber in (G) contains a more typical buildup (n = 35; ∼16%). The dot plot indicates the percentage of normal/near normal fibers from treated KO compared to untreated KO mice. Graphs represent mean ± SD. Scale bars, 20 μm. (See also Figure S1).