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Tyrosine phosphorylation in early embryonic growth cones
1Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, Florida 33136.
Summary
Tyrosine kinases and phosphatases are concentrated in growth cone particles, crucial for axon growth. The tyrosine kinase FYN plays a key role in early neuronal development.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Tyrosine phosphorylation is critical for axon growth.
- Growth cone particles (GCPs) are key structures in neuronal development.
Purpose of the Study:
- To investigate the subcellular distribution and developmental expression of enzymes regulating tyrosine phosphorylation in early embryonic brain.
- To elucidate the role of specific tyrosine kinases in growth cone function.
Main Methods:
- Isolation of growth cone particles (GCPs) from early embryonic brain.
- Assay of tyrosine kinase and phosphatase activity.
- Quantitative ELISA and Western blot analysis for tyrosine kinase expression.
- Immunofluorescence staining for cellular localization.
Main Results:
- GCPs showed high levels of GAP-43 and tyrosine kinase pp60c-src.
- Tyrosine kinase and phosphatase activities were concentrated in GCPs.
- Tyrosine kinases YES and FYN were also concentrated in GCPs.
- FYN expression peaks early in development, while YES expression peaks later.
- FYN is expressed in neurons, glia, and possibly precursor cells.
Conclusions:
- Multiple tyrosine kinases and phosphatases are involved in growth cone function.
- FYN's early expression and concentration in growth cones suggest a significant role in early neuronal development.