Abstract
Fetal alcohol spectrum disorder (FASD) is a leading cause of neurodevelopmental disability. Individuals with FASD may exhibit a characteristic facial appearance that has diagnostic utility. The mechanism by which alcohol disrupts craniofacial development is incompletely understood, as are the genetic factors that can modify individual alcohol vulnerability. Using an established avian model, we characterized the cranial transcriptome in response to alcohol to inform the mechanism underlying these cells’ vulnerability. Gallus gallus embryos having 3–6 somites were exposed to 52 mM alcohol and the cranial transcriptomes were sequenced thereafter. A total of 3422 genes had significantly differential expression. The KEGG pathways with the greatest enrichment of differentially expressed gene clusters were Ribosome (P = 1.2 x 10−17, 67 genes), Oxidative Phosphorylation (P = 4.8 x 10−12, 60 genes), RNA Polymerase (P = 2.2 x 10−3, 15 genes) and Spliceosome (P = 2.6 x 10−2, 39 genes). The preponderance of transcripts in these pathways were repressed in response to alcohol. These same gene clusters also had the greatest altered representation in our previous comparison of neural crest populations having differential vulnerability to alcohol-induced apoptosis. Comparison of differentially expressed genes in alcohol-exposed (3422) and untreated, alcohol-vulnerable (1201) transcriptomes identified 525 overlapping genes of which 257 have the same direction of transcriptional change. These included 36 ribosomal, 25 oxidative phosphorylation and 7 spliceosome genes. Using a functional approach in zebrafish, partial knockdown of ribosomal proteins zrpl11, zrpl5a, and zrps3a individually heightened vulnerability to alcohol-induced craniofacial deficits and increased apoptosis. In humans, haploinsufficiency of several of the identified ribosomal proteins are causative in craniofacial dysmorphologies such as Treacher Collins Syndrome and Diamond-Blackfan Anemia. This work suggests ribosome biogenesis may be a novel target mediating alcohol’s damage to developing neural crest. Our findings are consistent with observations that gene-environment interactions contribute to vulnerability in FASD.
Highlights
Fetal alcohol spectrum disorder (FASD) is a leading cause of permanent neurodevelopmental disability [1]
We found 3,422 genes were differentially expressed (BH corrected false discovery rate (FDR) at P < 0.10; S1 Table) between the transcriptomes of neural folds treated with alcohol or isotonic saline; the preponderance (80.6%, 2849 genes) were below the FDR cut-off of
We focused on ribosomal protein genes because they were the most significantly overrepresented KEGG pathway (Table 2), and they contribute to neural crest development [34]
Summary
Fetal alcohol spectrum disorder (FASD) is a leading cause of permanent neurodevelopmental disability [1]. Work in animal models shows that prenatal alcohol exposure (PAE) disrupts neurodevelopmental events including neuronal survival, proliferation, migration, and synaptogenesis [4]. We and others have reported that alcohol causes the apoptotic death of an early neuroprogenitor population called the neural crest [6,7,8]. Using an established chick embryo model of alcohol exposure, we showed that alcohol causes craniofacial structural changes consistent with those of the human disorder [6,9]. We further showed that alcohol causes apoptosis within neural crest progenitors because it elicits the phosphoinositide-mediated efflux of calcium from intracellular stores [11]. The subsequent activation of CaMKII phosphorylates and destabilizes transcriptionally active β-catenin, removing essential trophic support from these cells [12,13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
