title: Repulsive guidance molecule b inhibits neurite growth and is increased after spinal cord injury.
abstract: Neuronal axons are guided by attractive and repulsive cues in their local environment. Since the identification of the repulsive guidance molecule (RGM) a (RGMa) as an axon repellent in the visual system, diverse functions, as part of the developing and adult central nervous system (CNS), have been ascribed to it. The binding of RGMa to its receptor neogenin has been shown to induce RhoA activation, leading to inhibitory/repulsive behavior and the collapse of the neuronal growth cone. In this paper, we provide evidence to suggest the involvement of RGMb, another member of the RGM family, in the rat CNS. RGMb inhibits neurite outgrowth in postnatal cerebellar granule neurons (CGNs) in vitro. RGMb is expressed by oligodendrocytes and neurons in the adult rat CNS, and the expression of this molecule is upregulated around the site of spinal cord injury. RGMb is present in myelin isolated from an adult rat brain. RGMb and neogenin are coexpressed in CGNs and entorhinal cortex neurons. These findings suggest that RGMb is a myelin-derived inhibitor of axon growth in the CNS. Inhibition of RGMb may provide an alternative approach for the treatment of spinal injuries.
authors.affiliation: Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Xiaoxiang
authors.initials: X
authors.lastname: Liu
authors.forename: Motonori
authors.initials: M
authors.lastname: Hashimoto
authors.forename: Hajime
authors.initials: H
authors.lastname: Horii
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamaguchi
authors.forename: Koji
authors.initials: K
authors.lastname: Naito
authors.forename: Toshihide
authors.initials: T
authors.lastname: Yamashita