Notch signaling in the central nervous system with special reference to its expression in microglia

Notch signaling pathway is a major player in normal development in neurons, oligodendrocytes and astrocytes as well as neurological disorders of the central nervous system (CNS). Microglia, one of the major types of glial cells in the CNS, partakes in diverse roles within the CNS mainly related to normal brain development and inflammatory diseases, yet the involvement of Notch signaling pathway in microglia has remained elusive and has only recently been recognized suggesting its putative role in microglial maturation and activation. Notch ligands and receptors are constitutively expressed by microglia in developing brain. Notch signaling pathway is important for the maintenance of microglial population during early development as in other glial cells in normal development. Remarkably, Notch signaling pathway is also involved in microglial activation and inflammation process in neuroinflammatory diseases in both postnatal and adult rats. Targeting Notch signaling is therefore a promising strategy for prevention of neurodevelopmental diseases and development of future therapies for the treatment of neuroinflammatory disorders. This review highlights some recent findings of Notch signaling in microglia, both in normal development and pathological conditions.