Neuritogenesis governs developmental migration, axonogenesis and dendritic arborization of neurons, CNS phenomena which are aberrant in: experimental FAS. Neuritogenesis depends mechanistically upon l) plasma membrane- substratum adhesion and 2) neurital plasma membrane extension. The simple gangliosides GM3 and GD3 promote plasma membrane integrin-regulated and carbohydrate shear-modulated substrate adhesion. Synthesis of GM3/GD3 by IC-Golgi derived exofacial (ecto) sialyl transferases relocated within EGF-induced recycling endosomes, which are formed by EGF-induced endocytosis, may be a unique neuronal mechanism for promoting adhesion, by producing targeted localization of plasma membrane GM3/GD3. Chronic exposure of cells to ethanol reduces EGF-receptor (EGFR) endocytosis, thus limiting endosomal GM3/GD3 re-tailoring, and weakening adhesion loci. The effects of chronic ethanol exposure on GM3/GD3 sialylation in EGFR-induced endosomes will be quantitated in both a chick neuron culture and in an in ovo FAS model. Neurite plasma membrane extension requires addition to the plasma membrane of Golgi-derived plasma membrane elements with a very high structural content of neuritogenic (terminally-sialylated gangliotetraosyl ceramide) ganglioside glycoforms, particularly the major gangliosides GT1b, GQ1b Attenuated neuritogenesis results from inhibition of cytoskeletally regulated anterograde Golgi biosynthesis of GT1B, GQ1b. Dose-and time- dependent chronic ethanol-induced inhibition of biosynthesis of these gangliosides in neuron culture and a parallel whole embryo in ovo FAS model will be traced with [3H)ManNAc, as an obligate sialic acid precursor. Vulnerability of the differentiating embryonic CNS neuron to chronic ethanol-induced biosynthetic inhibition of sialylation of key neuronal gangliosides will be documented in detail. Evaluation will be made of exogenous re-supply of the neurital plasma membrane with building black gangliosides (GT1b/GQ1b) in neurite preservation A) in neuron culture and B) in vivo in embryonic chick brain, during chronic exposure to ethanol.

Agency
National Institute of Health (NIH)
Institute
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Type
Research Project (R01)
Project #
1R01AA009660-01A4
Application #
2045923
Study Section
Special Emphasis Panel (SRCA (52))
Project Start
1996-05-01
Project End
1996-08-31
Budget Start
1996-05-01
Budget End
1996-08-31
Support Year
1
Fiscal Year
1996
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
119132785
City
Los Angeles
State
CA
Country
United States
Zip Code
90095