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Regulation of myelin oligodendrocyte glycoprotein in different species throughout development
A J Slavin1, T G Johns, J M Orian
1Neuroimmunology Laboratory, La Trobe University, Bundoora, Australia.
Abstract:
The assembly and function of central nervous system (CNS) myelin requires the coordinated expression of several myelin-specific proteins, including myelin oligodendrocyte glycoprotein (MOG). Despite the recent cloning of MOG, the function of this molecule is still unknown. Because MOG is a late marker of oligodendrocyte maturation and is exclusively expressed in the CNS on the outermost lamellae of the myelin membrane, it is possible that this molecule plays an important role in the control and maintenance of myelination. Furthermore, as a member of the immunoglobulin superfamily that carries the L2/HNK-1 epitope, it has also been suggested that MOG is involved in cell-cell interaction, perhaps functioning as an adhesive molecule for bundles of nerve fibres. In order to further delineate the role of MOG throughout development we have analysed, by immunoblotting, the developmental appearance and accumulation pattern of MOG in the CNS of three mammalian species. We have also purified MOG to homogeneity from five different species including rat, guinea pig, bovine, monkey and human. Immunoblotting revealed two major MOG bands at 28 and 55 kD in all species. The 55 kD band appears to be a dimer of the lower band although treatment with 2-mercaptoethanol or EDTA failed to abolish it. Purified MOG from all species also displayed faint reactivity with bands at 36, 48 and 78 kD. While the 78 kD band may represent a trimer of MOG, the identity of the other bands remains unknown. Developmental studies in mouse, rat, guinea pig and bovine showed at as for other myelin proteins, MOG displayed a caudorostral gradient of expression, appearing in the spinal cord before the brain. The sensitivity of the detection system used here allowed us to detect MOG protein earlier than in previous reports such that its presence was clearly demonstrated in the CNS of mice and rats at 14 and 10 days after birth, respectively. Analysis of MOG expression in a novel transgenic mouse model that has both delayed and reduced myelination revealed that, like other myelin proteins, MOG expression was delayed compared with normal littermates. These results demonstrate that the expression of MOG is similar in all species and is regulated in a manner consistent with other myelin-specific proteins.
Insights
Myelin oligodendrocyte glycoprotein (MOG) is a key CNS myelin protein. Its expression pattern across species and developmental stages suggests a role in myelination control and maintenance.
Area of Science:
- Neuroscience
- Molecular Biology
- Developmental Biology
Background:
- Central nervous system (CNS) myelin assembly requires coordinated expression of myelin-specific proteins.
- Myelin oligodendrocyte glycoprotein (MOG) is a late-maturation marker exclusively expressed on the outermost myelin membrane.
- MOG's function remains largely unknown, but its characteristics suggest roles in myelination control and cell-cell interactions.
Purpose of the Study:
- To investigate the developmental expression and accumulation patterns of MOG in the CNS of multiple mammalian species.
- To purify MOG from various species to better understand its molecular characteristics.
- To analyze MOG expression in a transgenic mouse model with altered myelination.
Main Methods:
- Immunoblotting was used to analyze MOG's developmental appearance and accumulation in the CNS of three mammalian species.
- MOG was purified to homogeneity from five different species (rat, guinea pig, bovine, monkey, human).
- MOG expression was analyzed in a transgenic mouse model with delayed and reduced myelination.
Main Results:
- Immunoblotting revealed two major MOG bands (28 and 55 kD) across all species, with the 55 kD band likely representing a dimer.
- Purified MOG showed additional faint bands at 36, 48, and 78 kD, suggesting potential post-translational modifications or oligomeric forms.
- Developmental studies demonstrated a caudorostral gradient of MOG expression, appearing first in the spinal cord, and detected MOG earlier than previously reported.
- MOG expression was delayed in transgenic mice with impaired myelination, mirroring other myelin proteins.
Conclusions:
- MOG expression is conserved across mammalian species and follows a developmental pattern consistent with other myelin-specific proteins.
- The developmental regulation of MOG supports its role in the control and maintenance of CNS myelination.
- Further research is needed to elucidate the precise function of MOG and the identity of its various molecular forms.