Developmental Expression of the Oligodendrocyte Myelin Glycoprotein in the Mouse Telencephalon

Abstract

The oligodendrocyte myelin glycoprotein is a glycosylphosphatidylinositol-anchored protein expressed by neurons and oligodendrocytes in the central nervous system. Attempts have been made to identify the functions of the myelin-associated inhibitory proteins (MAIPs) after axonal lesion or in neurodegeneration. However, the developmental roles of some of these proteins and their receptors remain elusive. Recent studies indicate that NgR1 and the recently discovered receptor PirB restrict cortical synaptic plasticity. However, the putative factors that trigger these effects are unknown. Because Nogo-A is mostly associated with the endoplasmic reticulum and myelin associated glycoprotein appears late during development, the putative participation of OMgp should be considered. Here, we examine the pattern of development of OMgp immunoreactive elements during mouse telencephalic development. OMgp immunoreactivity in the developing cortex follows the establishment of the thalamo-cortical barrel field. At the cellular level, we located OMgp neuronal membranes in dendrites and axons as well as in brain synaptosome fractions and axon varicosities. Lastly, the analysis of the barrel field in OMgp-deficient mice revealed that although thalamo-cortical connections were formed, their targeting in layer IV was altered, and numerous axons ectopically invaded layers II-III. Our data support the idea that early expressed MAIPs play an active role during development and point to OMgp participating in thalamo-cortical connections.

Age-Dependent Decline of Nogo-A Protein in the Mouse Cerebrum

“…Previous reports have shown similar results on the effect of age on Nogo-A level. For example, immunoblotting analyses have shown to decrease in expression of Nogo-A protein in developing telencephalon from embryo on day 16 to adult stages (Gil et al 2010). Similar finding is also reported by Mingorance et al (2004) where they have shown decrease in expression of Nogo-A from the day of birth (postnatal day 0) to adult stage in developing hippocampus.…”

Expression of Nogo receptor 1 in the regeneration process of the mouse olfactory epithelium

“…The literature reveals that MAIs are not only expressed on the surfaces of axons but are also expressed in the synapses, which suggests that MAIs might participate in synaptic plasticity and stability [21] because receptors for Nogo-A, OMgp, NgR, and PirB are also expressed in the synapses. Indeed PirB expression was firstly detected close to the presynaptic membrane of neurons, which indicates that PirB localizes in or close to the synapses.…”

Myelin-associated inhibitors in axonal growth after CNS injury

“…Its role in developmental axon sprouting is still poorly understood [18]. Interestingly, OMgp is involved in the regulation of synaptic plasticity and activity-dependent synaptic strength [19], and it may influence axonal target specification during the development of thalamocortical projections [20]. In three independent studies, genetically deleting OMgp did not promote CST axon regeneration [9••,10••,21].…”