Oligodendrocyte differentiation and myelination defects in OMgp null mice.

OMgp is selectively expressed in CNS by oligodendrocyte. However, its potential role(s) in oligodendrocyte development and myelination remain unclear. We show that OMgp null mice are hypomyelinated in their spinal cords, resulting in slower ascending and descending conduction velocities compared to wild-type mice.

Assessment of functional recovery and axonal sprouting in oligodendrocyte-myelin glycoprotein (OMgp) null mice after spinal cord injury.

Oligodendrocyte-myelin glycoprotein (OMgp) is a myelin component that has been shown in vitro to inhibit neurite outgrowth by binding to the Nogo-66 receptor (NgR1)/Lingo-1/Taj (TROY)/p75 receptor complex to activate the RhoA pathway. To investigate the effects of OMgp on axon regeneration in vivo, OMgp(-/-) mice on a mixed 129/Sv/C57BL/6 (129BL6) or a C57BL/6 (BL6) genetic background were tested in two spinal cord injury (SCI) models - a severe complete transection or a milder dorsal hemisection. OMgp(-/-) mice on the mixed 129BL6 genetic background showed greater functional improvement compared to OMgp(+/+) littermates, with increased numbers of cholera toxin B-labeled ascending sensory axons and 5-HT(+) descending axons and less RhoA activation after spinal cord injury.

NGF regulates the expression of axonal LINGO-1 to inhibit oligodendrocyte differentiation and myelination.

Neurons and glia share a mutual dependence in establishing a functional relationship, and none is more evident than the process by which axons control myelination. Here, we identify LRR and Ig domain-containing, Nogo receptor-interacting protein (LINGO-1) as a potent axonal inhibitor of oligodendrocyte differentiation and myelination that is regulated by nerve growth factor and its cognate receptor TrkA in a dose-dependent manner. Whereas LINGO-1 expressed by oligodendrocyte progenitor cells was previously identified as an inhibitor of differentiation, we demonstrate that axonal expression of LINGO-1 inhibits differentiation with equal potency.

NG2 glial cells provide a favorable substrate for growing axons.

NG2 cells (polydendrocytes) comprise an abundant glial population that is widely and uniformly distributed throughout the developing and mature CNS and are identified by the expression of the NG2 proteoglycan at the cell surface. Although recent electrophysiological studies suggest that they are capable of receiving signals from axon terminals, other studies, based on the finding that the NG2 molecule itself induces growth cone collapse, have led to a widely held speculation that NG2 cells themselves also repel and inhibit growing axons. In this study, we have examined the effects of rat NG2 cells on growing hippocampal and neocortical axons in vitro and in vivo.

Astrocytes and NG2-glia: what's in a name?

Classic studies recognize two functionally segregated macroglial cell types in the central nervous system (CNS), namely astrocytes and oligodendrocytes. A third macroglial cell type has now been identified by its specific expression of the NG2 chondroitin sulphate proteoglycan (NG2-glia). These NG2-glia exist abundantly in both grey and white matter of the mature CNS and are almost as numerous as astrocytes.

Optimization of oligodendrocyte progenitor cell culture method for enhanced survival.

Oligodendrocyte progenitor cells (OPCs, NG2 glia) play an important role not only as progenitor cells that give rise to myelinating cells in the central nervous system (CNS), but also as an active participant in the neural network. It is necessary to develop a simplified method for generating large quantities of highly purified OPCs for biochemical studies and to establish a neuron-OPC coculture method for functional studies on the mechanism of neuron-OPC signaling. In this study, we have compared the effects of plating density and culture medium on purity, survival, and differentiation of cells collected from primary rat mixed glial cultures by differential adhesion.

Identity, distribution, and development of polydendrocytes: NG2-expressing glial cells.

Cells that express the NG2 proteoglycan (NG2+ cells) comprise a unique population of glial cells in the central nervous system. While there is no question that some NG2+ cells differentiate into oligodendrocytes during development, the persistence of numerous NG2+ cells in the mature CNS has raised questions about their identity, relation to other CNS cell types, and functions besides their progenitor role. NG2+ cells also express the alpha receptor for platelet-derived growth factor (PDGF alphaR), a receptor that mediates oligodendrocyte progenitor proliferation during development.