Autologous transplantation of SM/C-2.6(+) satellite cells transduced with micro-dystrophin CS1 cDNA by lentiviral vector into mdx mice.

Duchenne muscular dystrophy (DMD) is a lethal muscle disorder caused by mutations in the dystrophin gene. Transplantation of autologous myogenic cells genetically corrected ex vivo is a possible treatment for this disorder. In order to test the regenerative efficiency of freshly isolated satellite cells, we purified quiescent satellite cells from limb muscles of 8-12-week-old green fluorescent protein-transgenic (GFP-Tg) mice using SM/C-2.

Molecular signature of quiescent satellite cells in adult skeletal muscle.

Skeletal muscle satellite cells play key roles in postnatal muscle growth and regeneration. To study molecular regulation of satellite cells, we directly prepared satellite cells from 8- to 12-week-old C57BL/6 mice and performed genome-wide gene expression analysis. Compared with activated/cycling satellite cells, 507 genes were highly upregulated in quiescent satellite cells.

Functional heterogeneity of side population cells in skeletal muscle.

Skeletal muscle regeneration has been exclusively attributed to myogenic precursors, satellite cells. A stem cell-rich fraction referred to as side population (SP) cells also resides in skeletal muscle, but its roles in muscle regeneration remain unclear. We found that muscle SP cells could be subdivided into three sub-fractions using CD31 and CD45 markers.

AAV vector-mediated microdystrophin expression in a relatively small percentage of mdx myofibers improved the mdx phenotype.

Duchenne muscular dystrophy (DMD) is a lethal disorder of skeletal muscle caused by mutations in the dystrophin gene. Adeno-associated virus (AAV) vector-mediated gene therapy is a promising approach to the disease. Although a rod-truncated microdystrophin gene has been proven to ameliorate dystrophic phenotypes, the level of microdystrophin expression required for effective gene therapy by an AAV vector has not been determined yet.

Skeletal muscle gene expression in space-flown rats.

Skeletal muscles are vulnerable to marked atrophy under microgravity. This phenomenon is due to the transcriptional alteration of skeletal muscle cells to weightlessness. To further investigate this issue at a subcellular level, we examined the expression of approximately 26,000 gastrocnemius muscle genes in space-flown rats by DNA microarray analysis.

Isolation and characterization of a novel gene sfig in rat skeletal muscle up-regulated by spaceflight (STS-90).

We obtained the skeletal muscle of rats exposed to weightless conditions during a 16-day-spaceflight (STS-90). By using a differential display technique, we identified 6 up-regulated and 3 down-regulated genes in the gastrocnemius muscle of the spaceflight rats, as compared to the ground control. The up-regulated genes included those coding Casitas B-lineage lymphoma-b, insulin growth factor binding protein-1, titin and mitochondrial gene 16 S rRNA and two novel genes (function unknown).

A relative high dose of vitamin E does not attenuate unweighting-induced oxidative stress and ubiquitination in rat skeletal muscle.

We previously reported that intragastric administration of cysteine could be beneficial to prevent unweighting-induced ubiquitination and degradation of muscle protein in association with redox regulation [Ikemoto et al., Biol. Chem.

Effects of a soy protein diet on exercise-induced muscle protein catabolism in rats.

Objective: We examined effects of dietary soy protein isolate on muscle calpain activity and myosin heavy chain (MHC) degradation in rats performing an acute running exercise.

Methods: In rats fed a 20% casein diet, the treadmill running exercise, fixed at 80 kg/m, transiently increased calpain activity in gastrocnemius muscles in parallel with the release of creatine kinase into plasma. The fixed running also caused an accumulation of immunoreactive degradation fragments of MHC in the muscle.

Cysteine supplementation prevents unweighting-induced ubiquitination in association with redox regulation in rat skeletal muscle.

We have previously reported that spaceflight and tail suspension enhanced degradation of rat myosin heavy chain (MHC) in association with activation of a ubiquitin-dependent proteolytic pathway [Ikemoto et al., FASEB J. 15 (2001), 1279-1281].

A cysteine protease inhibitor prevents suspension-induced declines in bone weight and strength in rats.

In this study, we examined the effects of a potent cysteine protease inhibitor, N-(L-3-trans-carboxyoxirane-2-cabonyl)-L-leucine-4-aminobutylamide (E-64a), on bone weight and strength in tail-suspended rats. We first administered a vehicle or 4 or 8 mg/rat of E-64a to rats fed with a low calcium diet for 7 wks to determine effective doses of E-64a on bone resorption in vivo. Femoral cathepsin K-like activity and serum hydroxyproline level in rats fed with a low calcium diet were significantly higher than those in rats fed with a standard diet.