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Abstract:
Myelin-deficient mutant mice, such as shiverer, can provide information about the normal mechanisms involved in myelination. The shiverer mouse carries a recessive, autosomal mutation resulting in an extreme deficiency in central myelin, and the small amount of myelin present is poorly compacted; the peripheral myelin, however, appears essentially normal. As the amount of myelin basic protein (P1) in both central and peripheral nervous system myelin is extremely low in shiverer, it is possible that P1 is essential for the normal formation and compaction of central myelin, but not of peripheral myelin. Some other protein would then be responsible for the formation of compact peripheral myelin in shiverer. Peripheral myelin contains another basic protein, designated P2, which could be a possible candidate for this role. Kirschner and Ganser, however, using SDS-polyacrylamide gel electrophoresis, reported that P2, as well as P1, is absent from shiverer sciatic nerve. This is an important observation if correct, because it not only excludes the possibility that P2 is required for compaction but also makes it less likely that the deficiency in P1 is the primary defect in shiverer. As P2 in rat and mouse has frequently been confused with another small basic protein (related to P1) in SDS-polyacrylamide gels, it seemed worthwhile to reassess this aspect of the Kirschner and Ganser observations. Immunohistochemistry and immunoblotting have been used here to show unambiguously that P2 is present in shiverer peripheral myelin.
Insights
Shiverer mice have defective central nervous system myelin. This study confirms myelin basic protein P2 is present in their peripheral myelin, challenging previous findings.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Myelination is crucial for nervous system function.
- The shiverer mouse mutant exhibits deficiencies in central nervous system (CNS) myelin.
- Peripheral myelin in shiverer mice appears largely normal, suggesting alternative mechanisms for its formation.
Purpose of the Study:
- To investigate the role of myelin basic protein (P1) in myelination.
- To determine the presence of P2 protein in the peripheral myelin of shiverer mice.
- To re-evaluate previous findings regarding P2 protein absence in shiverer sciatic nerve.
Main Methods:
- Immunohistochemistry was employed to detect P2 protein.
- Immunoblotting techniques were utilized for protein analysis.
- SDS-polyacrylamide gel electrophoresis was used for comparison with prior studies.
Main Results:
- Myelin basic protein P1 is deficient in both CNS and peripheral myelin of shiverer mice.
- Previous reports suggested P2 protein was absent in shiverer peripheral myelin.
- This study unambiguously demonstrates the presence of P2 protein in shiverer peripheral myelin.
Conclusions:
- The presence of P2 in shiverer peripheral myelin suggests it may play a role in peripheral myelin compaction.
- The findings challenge the hypothesis that P1 is solely responsible for central myelin compaction.
- Reassessment of P2 protein presence is critical for understanding myelination defects in shiverer mutants.