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Published on: September 18, 2014
Identification of a mitogen-activated protein kinase site in human myelin basic protein in situ
M Yon1, C A Ackerley, F G Mastronardi
1School of Biological and Molecular Sciences, Oxford Brookes University, Headington, UK.
Abstract:
Ultrastructural localization of a specific phosphorylated isomer of myelin basic protein (MBP) has been achieved with a monoclonal antibody specific for human MBP sequence, 89-105, in which Thr98 was phosphorylated. Cryosections of human brain white matter revealed that gold particles were found localized almost exclusively to the major dense line demonstrating that threonine 98 in the sequence Thr-Pro-Arg-Thr-Pro-Pro-Pro, a mitogen-activated protein kinase-specific site, was phosphorylated in vivo. In two cases of multiple sclerosis, the density of gold particles in myelin was reduced by about 30%, in one case by 42%, and by 80% in a fourth case. However, gold labelling was seen in areas of demyelination suggesting that the phosphorylated threonyl peptide was protected from degradation.
Insights
Researchers identified phosphorylated myelin basic protein (MBP) in human brain white matter. This specific phosphorylated form was reduced in multiple sclerosis, but present in demyelinated areas, suggesting protection from degradation.
Area of Science:
- Neuroscience
- Biochemistry
- Immunology
Background:
- Myelin basic protein (MBP) is crucial for myelin sheath integrity in the central nervous system.
- Phosphorylation of MBP can alter its structure and function.
- Understanding MBP phosphorylation is vital for studying myelin disorders.
Purpose of the Study:
- To ultrastructurally localize a specific phosphorylated isomer of MBP in human brain white matter.
- To investigate the in vivo phosphorylation status of Thr98 in MBP.
- To examine changes in phosphorylated MBP in multiple sclerosis.
Main Methods:
- Utilized a monoclonal antibody specific for human MBP sequence 89-105 with phosphorylated Thr98.
- Performed cryosectioning of human brain white matter.
- Employed immunogold labeling for ultrastructural localization.
Main Results:
- Gold particles localized to the major dense line of myelin, confirming in vivo phosphorylation of Thr98.
- Reduced gold particle density (30-80%) observed in myelin of multiple sclerosis cases.
- Phosphorylated MBP was detected in areas of demyelination, indicating protection from degradation.
Conclusions:
- Thr98 phosphorylation of MBP occurs in vivo within the major dense line of myelin.
- Multiple sclerosis is associated with reduced levels of this specific phosphorylated MBP.
- The phosphorylated peptide may be protected from degradation in demyelinated lesions.
