Satellite cell senescence underlies myopathy in a mouse model of limb-girdle muscular dystrophy 2H
Elena Kudryashova, … , Irina Kramerova, Melissa J. Spencer
Elena Kudryashova, … , Irina Kramerova, Melissa J. Spencer
Published April 16, 2012
Citation Information: J Clin Invest. 2012;122(5):1764-1776. https://doi.org/10.1172/JCI59581.
View: Text | PDF
Research Article Muscle biology Article has an altmetric score of 7

Satellite cell senescence underlies myopathy in a mouse model of limb-girdle muscular dystrophy 2H

Abstract

Mutations in the E3 ubiquitin ligase tripartite motif-containing 32 (TRIM32) are responsible for the disease limb-girdle muscular dystrophy 2H (LGMD2H). Previously, we generated Trim32 knockout mice (Trim32–/– mice) and showed that they display a myopathic phenotype accompanied by neurogenic features. Here, we used these mice to investigate the muscle-specific defects arising from the absence of TRIM32, which underlie the myopathic phenotype. Using 2 models of induced atrophy, we showed that TRIM32 is dispensable for muscle atrophy. Conversely, TRIM32 was necessary for muscle regrowth after atrophy. Furthermore, TRIM32-deficient primary myoblasts underwent premature senescence and impaired myogenesis due to accumulation of PIAS4, an E3 SUMO ligase and TRIM32 substrate that was previously shown to be associated with senescence. Premature senescence of myoblasts was also observed in vivo in an atrophy/regrowth model. Trim32–/– muscles had substantially fewer activated satellite cells, increased PIAS4 levels, and growth failure compared with wild-type muscles. Moreover, Trim32–/– muscles exhibited features of premature sarcopenia, such as selective type II fast fiber atrophy. These results imply that premature senescence of muscle satellite cells is an underlying pathogenic feature of LGMD2H and reveal what we believe to be a new mechanism of muscular dystrophy associated with reductions in available satellite cells and premature sarcopenia.

Authors

Elena Kudryashova, Irina Kramerova, Melissa J. Spencer

×

Figure 9

Satellite cell number is reduced in Trim32–/– muscles during muscle reloading.

Options: View larger image (or click on image) Download as PowerPoint
Satellite cell number is reduced in Trim32–/– muscles during muscle relo...
(A) Representative Western blots of soleus muscle extracts from ambulatory control mice, mice suspended for 5 days (suspension), or mice reloaded for 3 days after suspension (reloading) were stained with Pax7 (2 blots are shown) and PIAS4. An anti-desmin blot is shown as a loading control. Densitometry data (n = 4) of (B) PIAS4 and (C) Pax7 blots were normalized to desmin and shown as mean ± SEM (*P < 0.05). (D) Frozen sections of Trim32+/+ and Trim32–/– soleus muscles from control mice and mice subjected to reloading for 3 days after suspension were stained with Pax7. Pax7-positive satellite cells appear on the micrographs as black dots (examples are indicated by arrows). Scale bar: 50 μm. (E) The amount of Pax7-positive cells was quantified in 3 independent fields of view per each slide. Data (n = 6) are shown as mean ± SEM (*P < 0.05). (F) Frozen sections of ambulatory control Trim32–/– and Trim32+/+ mice were immunostained with anti-fast and anti-slow myosin antibodies. Fiber area measurements show a significant decrease in the average cross-sectional area for fast fibers in soleus (n = 6) and gastrocnemius (gastroc) (n = 3) muscles of the Trim32–/– animals (18.1% and 21.04%, correspondingly). 100–300 fibers were measured per each slide. Data are shown as mean ± SEM (*P < 0.05).