Fetal alcohol spectrum disorder (FASD) is the most common preventable cause of mental retardation in the Western World. Our research addresses FASD and has three broad goals: to better understand how ethanol disrupts fetal development;to identify biological factors that increase the susceptibility of women who drink during pregnancy to bear children with FASD;and to provide a scientific foundation for rational drug design to prevent or mitigate FASD. Our major focus is the L1 cell adhesion molecule, a developmentally critical protein that is implicated in the pathophysiology of FASD. Ethanol potently inhibits L1 adhesion and L1-mediated neurite outgrowth, and photolabeling identifies a binding pocket on the extracellular domain of L1 (L1-ECD) in which point mutations alter the effects of ethanol. The proposed research will test three principal hypotheses: 1) there is a specific location at the interface between L1 Ig1 and Ig4 at which ethanol alters L1 function by disrupting the horseshoe conformation of L1 that favors homophilic binding;2) phosphorylation within the L1 cytoplasmic domain (CD) modulates L1 sensitivity to ethanol by causing conformational changes in the alcohol binding pocket of the L1 extracellular domain (ECD);3) ethanol inhibition of L1 adhesion contributes to ethanol inhibition of L1-mediated neurite outgrowth (L1MNO). We will determine the effects of mutations that alter the ethanol binding pocket on the structure and function of L1. Structural changes will be detected by spinlabeling and double electron-electron resonance (DEER) protocols and by changes in the availability of sites for photolabeling by azialcohols. We will correlate structure with function by examining the effects of mutations on L1 adhesion, alcohol inhibition of L1 adhesion, and antagonist blockade of ethanol inhibition of cell adhesion using intact NIH/3T3 cells transiently transfected with L1 constructs. We will employ kinase inhibitors and mutations of specific kinase substrates in the L1-CD to determine how these sites regulate ethanol sensitivity. We will evaluate the effects of L1-CD phosphorylation on L1-ECD structure by determining whether L1-CD mutations prevent the formation of disulfide bonds between two cysteine reporters inserted within the alcohol binding pocket in the L1-ECD. We will also study masking or unmasking of antibody epitopes within the L1- ECD and alcohol inhibition of L1 adhesion in response to mutation of kinase substrates in the L1-CD. We will determine whether the pharmacology is similar for alcohol inhibition of L1 adhesion and L1MNO in cerebellar granule neurons. We will also study whether mutations that block ethanol inhibition of L1 adhesion also block ethanol inhibition of L1MNO. These experiments will expand our knowledge of how ethanol disrupts fetal development, why individuals differ in sensitivity to ethanol teratogenesis, and how drugs might be designed to reduce ethanol toxicity.
Fetal alcohol spectrum disorders (FASD) results from drinking during pregnancy and is the most common, preventable cause of mental retardation in the United States. Approximately 1 to 3 per 1000 children are born with full fetal alcohol syndrome and as many as 1 in 100 live births have behavioral and neurological abnormalities, birth defects, or other elements of FASD. Our work is directed at identifying biological factors that increase a women's susceptibility to bear children with FASD and discovering medications that will prevent or mitigate the development of FASD.
|Charness, Michael E; Riley, Edward P; Sowell, Elizabeth R (2016) Drinking During Pregnancy and the Developing Brain: Is Any Amount Safe? Trends Cogn Sci 20:80-2|
|Dou, Xiaowei; Charness, Michael E (2014) Effect of lipid raft disruption on ethanol inhibition of l1 adhesion. Alcohol Clin Exp Res 38:2707-11|
|Dou, Xiaowei; Wilkemeyer, Michael F; Menkari, Carrie E et al. (2013) Mitogen-activated protein kinase modulates ethanol inhibition of cell adhesion mediated by the L1 neural cell adhesion molecule. Proc Natl Acad Sci U S A 110:5683-8|
|Chen, Suzhen; Charness, Michael E (2012) Ethanol disrupts axon outgrowth stimulated by netrin-1, GDNF, and L1 by blocking their convergent activation of Src family kinase signaling. J Neurochem 123:602-12|
|Parnell, Scott E; Sulik, Kathleen K; Dehart, Deborah B et al. (2010) Reduction of ethanol-induced ocular abnormalities in mice through dietary administration of N-acetylcysteine. Alcohol 44:699-705|
|Yan, Dong; Dong, Jian; Sulik, Kathleen K et al. (2010) Induction of the Nrf2-driven antioxidant response by tert-butylhydroquinone prevents ethanol-induced apoptosis in cranial neural crest cells. Biochem Pharmacol 80:144-9|
|Dong, Jian; Sulik, Kathleen K; Chen, Shao-yu (2010) The role of NOX enzymes in ethanol-induced oxidative stress and apoptosis in mouse embryos. Toxicol Lett 193:94-100|
|Dong, Jian; Sulik, Kathleen K; Chen, Shao-Yu (2008) Nrf2-mediated transcriptional induction of antioxidant response in mouse embryos exposed to ethanol in vivo: implications for the prevention of fetal alcohol spectrum disorders. Antioxid Redox Signal 10:2023-33|
|Arevalo, Enrique; Shanmugasundararaj, Sivananthaperumal; Wilkemeyer, Michael F et al. (2008) An alcohol binding site on the neural cell adhesion molecule L1. Proc Natl Acad Sci U S A 105:371-5|
|Parnell, Scott E; Chen, Shao-yu; Charness, Michael E et al. (2007) Concurrent dietary administration of D-SAL and ethanol diminishes ethanol's teratogenesis. Alcohol Clin Exp Res 31:2059-64|
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