Nerve growth factor-induced myoprotection in C2C12 muscle cells is mediated by α9β1 integrin via release of PGE₂

Background: Nerve growth factor (NGF) mediates a wide range of activities in the central nervous system including neuronal differentiation, synaptic plasticity, and neuroprotection. In addition, NGF places an important role in skeletal muscle physiology by some unknown mechanisms. We recently demonstrated that NGF conferred myoprotection toward ischemia in C2C12 skeletal muscle cell model, establishing an important trophic role for NGF in skeletal muscle. Methods: In this report, using ELISA and oxygen-glucose deprivation (OGD) assays, we investigated the potential contribution of prostaglandin E₂ (PGE₂) to NGF myoprotective effects toward C2C12 cultures exposed to OGD insults. Vipera lebetina obtusa disintegrin 5 (VLO5), a selective antagonist of α9β1 integrin, was used as an experimental tool to clarify α9β1 integrin role in NGF action. Results: NGF-induced mitogen-activated protein kinase type 1 or 2 (ERK1/2) phosphorylation in C2C12 cells and in a dose-response fashion stimulated PGE₂ release, both effects antagonized by VLO5 and PD98059. NGF-induced myoprotection of the cells exposed for 7 h to OGD, followed by 18 h of reoxygenation, was reversed by VLO5 treatment. Conclusions: These results suggest that NGF activation of α9β1 integrin induced myoprotection by stimulation of ERK phosphorylation and release of cytoprotective PGE₂ mediator. This effect may be also relevant for NGF-induced pain and hyperalgesia in the skeletal muscle.