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Secretion and processing of apolipoprotein A-I in the avian sciatic nerve during development
M J Lemieux1, C Mezei, W C Breckenridge
1Department of Biochemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
Journal of Neuroscience Research
|June 15, 1996
Summary
Apolipoprotein A-I (apo A-I) synthesis and processing in developing chick sciatic nerves are regulated alongside myelination. Apo A-I secretion increases, with a shift towards acidic isoforms during development.
Area of Science:
- Neuroscience
- Biochemistry
- Developmental Biology
Background:
- Apolipoprotein A-I (apo A-I) is crucial for lipid transport and has been found in avian sciatic nerves.
- Apo A-I mRNA and protein levels rise during rapid myelination in avian sciatic nerves.
Purpose of the Study:
- To investigate the synthesis and processing of apo A-I protein and its isoforms during chick sciatic nerve development.
- To correlate apo A-I synthesis and processing with myelination stages.
Main Methods:
- Incubation of endoneurial slices from embryonic and posthatch chick sciatic nerves with [35S]-methionine.
- Fractionation into secreted and intracellular components to assess labeled apo A-I and Po protein.
- Analysis of apo A-I isoform processing (acidic vs. basic).
Main Results:
- Methionine incorporation into Po protein peaked intracellularly at 15 days embryonic, then decreased with myelin accumulation.
- Nascent apo A-I levels increased in both secreted and intracellular fractions during development.
- Apo A-I synthesis increased specifically in the secreted fraction, and secretion shifted towards acidic isoforms with age.
Conclusions:
- Apo A-I secretion and processing are developmentally regulated in the chick sciatic nerve.
- These changes occur in parallel with active myelination, suggesting a coordinated biological process.
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