Ameliorating Effect of Osteopontin on H₂O₂-Induced Apoptosis of Human Oligodendrocyte Progenitor Cells

Recently our group used oligodendrocyte progenitor cells (OPCs) as appropriate model cells to pinpoint the mechanism of the progress of neurodegenerative disorders. In the present study, we focused on the therapeutic role of osteopontin (OPN), a secreted glycosylated phosphoprotein, involved in a number of physiological events including bone formation and remodeling, immune responses, and tumor progression. Protective role of OPN, as a negative regulator of tumorigenesis, has already been clarified. Human embryonic stem cell-derived OPCs were pretreated with OPN before induction of apoptosis by H₂O₂. Data indicated that OPN prohibited cell death and enhanced OPC viability. This effect is achieved through reduction of apoptosis and induction of anti-apoptosis markers. In addition OPN induces expression of several integrin subunits, responsible for OPN interaction. Notably, our findings showed that expression of αV β1/β3/β5 and β8 integrins increased in response to OPN, while treatment with H₂O₂ down-regulated αV β1/β5 and β8 integrins expression significantly. In conclusion, OPN may act via αV integrin signaling and trigger suppression of P53-dependent apoptotic cascades. Therefore OPN therapy may be considered as a feasible process to prevent progress of neurodegenerative diseases in human.