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Neurofilament phosphorylation is modulated by myelination
R Starr1, B Attema, G H DeVries
1Medical Biotechnology Center, University of Maryland Biotechnology Institute, University of Maryland School of Medicine, Baltimore 21201, USA.
Journal of Neuroscience Research
|May 15, 1996
Summary
Myelination by Schwann cells increases neurofilament (NF) phosphorylation in developing axons. This change in NF phosphorylation, regulated by specific kinases, is crucial for axonal growth during development.
Area of Science:
- Neuroscience
- Cell Biology
- Developmental Biology
Background:
- Axonal radial growth is a critical developmental process.
- Neurofilament (NF) phosphorylation is implicated in controlling axonal diameter.
- The precise regulation of NF phosphorylation during development remains unclear.
Purpose of the Study:
- To investigate the role of myelination in regulating neurofilament phosphorylation.
- To identify molecular mechanisms linking myelination to NF phosphorylation changes.
Main Methods:
- Utilized dorsal root ganglion (DRG)-Schwann cell co-cultures.
- Assessed NF phosphorylation using antibodies SMI31 (phosphorylated) and SMI32 (non-phosphorylated).
- Analyzed NF kinase activity using in situ gel kinase assays.
- Compared NF phosphorylation in co-cultures with sciatic nerve extracts from normal and Trembler J mice.
Main Results:
- Myelination by Schwann cells significantly increased NF phosphorylation in DRG neurons.
- Increased NF phosphorylation correlated with reduced non-phosphorylated NF epitopes (SMI32) and increased phosphorylated epitopes (SMI31).
- Myelination induced a 35-kDa kinase activity and decreased a 42-kDa kinase activity.
Conclusions:
- Myelination directly regulates neurofilament phosphorylation during axonal development.
- Specific changes in kinase activity accompany myelination-induced NF phosphorylation.
- These findings suggest neuron-glia signaling pathways involving kinases regulate axonal growth.