Key result
ANGPT2 promoted skeletal myoblast survival and differentiation through activation of the ERK1/2 and PI-3 kinase/AKT pathways, suggesting a positive role in skeletal muscle fiber repair.
Why the study?
Does ANGPT2 promote survival, proliferation, migration, and differentiation in primary skeletal myoblasts?
Does ANGPT2 promote survival, proliferation, migration, and differentiation in primary skeletal myoblasts?
ANGPT2 is constitutively expressed in skeletal muscle precursors, upregulated during differentiation, and promotes myoblast survival and differentiation, suggesting a role in muscle fiber repair.
Preclinical ANGPT2 effects on myoblasts warrant human studies; leaves open therapeutic translation in muscle injury.
BACKGROUND: Angiopoietin-1 (ANGPT1) and angiopoietin-2 (ANGPT2) are angiogenesis factors that modulate endothelial cell differentiation, survival and stability. Recent studies have suggested that skeletal muscle precursor cells constitutively express ANGPT1 and adhere to recombinant ANGPT1 and ANGPT2 proteins. It remains unclear whether or not they also express ANGPT2, or if ANGPT2 regulates the myogenesis program of muscle precursors. In this study, ANGPT2 regulatory factors and the effects of ANGPT2 on proliferation, migration, differentiation and survival were identified in cultured primary skeletal myoblasts. The cellular networks involved in the actions of ANGPT2 on skeletal muscle cells were also analyzed. METHODOLOGY/PRINCIPAL FINDINGS: Primary skeletal myoblasts were isolated from human and mouse muscles. Skeletal myoblast survival, proliferation, migration and differentiation were measured in-vitro in response to recombinant ANGPT2 protein and to enhanced ANGPT2 expression delivered with adenoviruses. Real-time PCR and ELISA measurements revealed the presence of constitutive ANGPT2 expression in these cells. This expression increased significantly during myoblast differentiation into myotubes. In human myoblasts, ANGPT2 expression was induced by H(2)O(2), but not by TNFα, IL1β or IL6. ANGPT2 significantly enhanced myoblast differentiation and survival, but had no influence on proliferation or migration. ANGPT2-induced survival was mediated through activation of the ERK1/2 and PI-3 kinase/AKT pathways. Microarray analysis revealed that ANGPT2 upregulates genes involved in the regulation of cell survival, protein synthesis, glucose uptake and free fatty oxidation. CONCLUSION/SIGNIFICANCE: Skeletal muscle precursors constitutively express ANGPT2 and this expression is upregulated during differentiation into myotubes. Reactive oxygen species exert a strong stimulatory influence on muscle ANGPT2 expression while pro-inflammatory cytokines do not. ANGPT2 promotes skeletal myoblast survival and differentiation. These results suggest that muscle-derived ANGPT2 production may play a positive role in skeletal muscle fiber repair.
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Mofarrahi et al. (2011) studied Skeletal muscle repair. Recombinant ANGPT2 protein and adenoviral ANGPT2 expression was evaluated on Myoblast survival, proliferation, migration and differentiation. ANGPT2 promoted skeletal myoblast survival and differentiation through activation of the ERK1/2 and PI-3 kinase/AKT pathways, suggesting a positive role in skeletal muscle fiber repair.