Three-dimensional niche stiffness synergizes with Wnt7a to modulate the extent of satellite cell symmetric self-renewal divisions.

Satellite cells (SCs), the resident adult stem cells of skeletal muscle, are required for tissue repair throughout life. While many signaling pathways are known to control SC self-renewal, less is known about the mechanisms underlying the spatiotemporal control of self-renewal during skeletal muscle repair. Here, we measured biomechanical changes that accompany skeletal muscle regeneration and determined the implications on SC fate.

Xin is a marker of skeletal muscle damage severity in myopathies.

Xin is a striated muscle-specific protein that is localized to the myotendinous junction in skeletal muscle. However, in injured mouse muscle, Xin expression is up-regulated and observed throughout skeletal muscle fibers and within satellite cells. In this study, Xin was analyzed by immunofluorescent staining in skeletal muscle samples from 47 subjects with various forms of myopathy, including muscular dystrophies, inflammatory myopathies, mitochondrial/metabolic myopathy, and endocrine myopathy.

Aerobic training as an adjunctive therapy to enzyme replacement in Pompe disease.

Background: Aerobic exercise may be used in conjunction with enzyme replacement therapy (ERT) to attenuate cardiovascular deconditioning, skeletal muscle wasting, and loss of motor function in Pompe disease (glycogen storage disease type II; GSDII), but the effects on lysosomal glycogen content and macroautophagy have not been defined to date.

Purpose: The main objectives of this study were to determine if acute aerobic exercise enhances 24-h uptake of recombinant human enzyme (rhGAA; Myozyme® [aim 1]) and if endurance training improves disease pathology when combined with ERT [aim 2] in Pompe mice.

Methods: For the first aim in our study, Pompe mutant mice (6(neo)/6(neo)) were grouped into ERT (Myozyme® injection only [40 mg/kg]) and ERT+EX (Myozyme® injection followed by 90 min treadmill exercise) cohorts, and enzyme uptake was assessed in the heart and quadriceps 24h post injection.

Skeletal muscle regeneration is delayed by reduction in Xin expression: consequence of impaired satellite cell activation?

Xin is a striated muscle-specific actin-binding protein whose mRNA expression has been observed in damaged skeletal muscle. Here we demonstrate increased Xin protein expression early postinjury (≤ 12 h) and localization primarily to the periphery of damaged myofibers. At 1 day postinjury, Xin is colocalized with MyoD, confirming expression in activated satellite cells (SCs).

Inhibition of plasminogen activator inhibitor-1 restores skeletal muscle regeneration in untreated type 1 diabetic mice.

Objective: Type 1 diabetes leads to impairments in growth, function, and regenerative capacity of skeletal muscle; however, the underlying mechanisms have not been clearly defined.

Research Design And Methods: With the use of Ins2(WT/C96Y) mice (model of adolescent-onset type 1 diabetes), muscle regeneration was characterized in terms of muscle mass, myofiber size (cross-sectional area), and protein expression. Blood plasma was analyzed for glucose, nonesterified fatty acids, insulin, and plasminogen activator inhibitor-1 (PAI-1).