Effect of ethanol on chondroitin sulfate proteoglycans: relevance to FASD

Ethanol exerts profound effects on the developing brain, which range from structural abnormalities to
functional anomalies, resulting in compromised cognitive and behavioral functions characteristic of fetal alcohol
spectrum disorders (FASD). Neuronal maturation is an essential process in the development of the nervous
system. Brain-specific chondroitin sulfate proteoglycans (CSPGs) neurocan and brevican constitute inhibitory
cues that prevent the extension of neurites in improper directions therefore contributing to the proper formation
of neuronal architecture. Neurocan and brevican inhibit neurite outgrowth and are highly produced by glial
cells, and astrocytes in particular, both in vitro and in vivo. CSPG are glycoproteins consisting of core-proteins
attached to linear chains of glycosaminoglycans (GAGs) called chondroitin sulfates (CS), which consists in
chondroitin-4 sulfate (C4S) and chondroitin-6 sulfate (C6S); the inhibitory properties of CSPGs depend on their
core-protein and their GAG chains. Several enzymes are involved in the biosynthesis and degradation of GAG
chains; arylsulfatase B (ARSB) and galactose-6-sulfatase (GALNS) remove sulfate groups from C4S and C6S
respectively and are required for the degradation of CS-GAGs. An unscheduled increase in CSPGs in the still
developing brain may lead to altered brain connectivity and to premature decrease in neuronal plasticity. In this
proposal we hypothesize that ethanol-treated astrocytes inhibits neuritogenesis by increasing CSPGs. More
specifically, we hypothesize that ethanol, through the inhibition of ARSB and GALNS activity in astrocytes,
increases CS-GAG and CSPG core-protein neurocan and brevican levels in these cells leading to the inhibition
of hippocampal neuron neuritogenesis. Specific aim 1 will investigate the effect of ethanol on ARSB and
GALNS activity and expression, on CS-GAG, neurocan, and brevican levels, and on the role of ARSB and
GALNS in modulating ethanol-induced inhibition of astrocyte-mediated hippocampal neuritogenesis in vitro.
Specific Aim 2 will investigate the effect of in vivo neonatal alcohol exposure on ARSB and GALNS activity and
protein and mRNA expression, CS-GAG, C4S-GAG, and neurocan- and brevican-bound sGAG levels, and
neurocan and brevican protein and mRNA expression in the hippocampus.