CRANIOFACIAL MORPHOGENESIS IN PRENATAL ALCOHOL EXPOSURE
Principal Investigator: Susan Smith
Abstract: Prenatal alcohol exposure (PAE) is the leading known cause of mental retardation and birth defects. Its teratogenicity originates, in part, through its initiation of apoptosis in critical cell populations. Under previous NIAAA support, we developed a chick embryo model of PAE and showed that ethanol causes the selective apoptosis of the neural crest, an embryonic cell population containing craniofacial and neuronal precursors. Here, we hypothesize that ethanol induces neural crest apoptosis by activating the phospholipase C-dependent release of intracellular Ca2+. This hypothesis is tested using pharmacologic approaches, taking advantage that we can locally target agonists and antagonists of Ca2+ signaling pathways to the premigratory neural crest in ovo, and thus test their ability to attenuate ethanol's effects upon the embryo. Experiments in this proposal test three sub-hypotheses: 1) Acute ethanol induces neural crest apoptosis by stimulating the release of intracellular Ca2+. The requirement for Ca2+ release is tested through the use of fluorescent Ca2+ indicators, Ca2+ ionophores and chelators, and the direct assay of downstream, Ca2+-dependent signaling proteins (CaM kinase, calcineurin). 2) Ethanol mobilizes intracellular Ca2+ and induces apoptosis by activating inositol triphosphate (IP3) receptors. Pharmacologic agonists and antagonists test that the ethanol-released Ca2+ originates from IP3-mediated stores; this IP3 release will be quantified directly. Potential contributions of ryanodine receptors and extracellular Ca2+ also are tested. 3) Ethanol's activation of Phospholipase C (PLC) is responsible for the Ca2+ release and neural crest apoptosis. PLC activation is measured by direct assay and by targeted inhibitors. Contributions of diacylglycerol, receptor-mediated tyrosine kinases, and receptor-mediated G proteins are investigated. these results address the molecular mechanism underlying the neural crest's sensitivity to ethanol, and, thus, contribute to understanding the basis for ethanol's teratogenicity. Results also may provide possible explanations for genetic-based variations in fetal responses to prenatal ethanol exposure.
Funding Period: 1996-07-01 - 2007-03-31
more information: NIH RePORT
- Ethanol exposure during the early first trimester equivalent impairs reflexive motor activity and heightens fearfulness in an avian modelSusan M Smith
Department of Nutritional Sciences, University of Wisconsin Madison, 1500 Highland Avenue, Madison, WI 53706, USA
Alcohol 45:57-63. 2011..The equivalent period in human development is 3-4 weeks postconception. The current findings emphasize that ethanol exposure during the early first trimester equivalent can produce neurodevelopmental disability in the offspring...
- Rapid induction of apoptosis in gastrulating mouse embryos by ethanol and its prevention by HB-EGFBrian A Kilburn
C S Mott Center for Human Growth and Development, Department of Obstetrics and Gynecology, Wayne State University, Detroit, Michigan 48201 1415, USA
Alcohol Clin Exp Res 30:127-34. 2006..Ethanol alters intracellular signaling, leading to cell death in chick embryos, suggesting that apoptosis could occur rapidly and that signaling pathways activated by survival factors might reduce apoptosis...
- Structural constraints for alcohol-stimulated Ca2+ release in neural crest, and dual agonist/antagonist properties of n-octanolAna Garic-Stankovic
Department of Nutritional Sciences, University of Wisconsin Madison, Madison, Wisconsin 53706, USA
Alcohol Clin Exp Res 30:552-9. 2006..We tested the hypothesis that ethanol's activity represents a saturable and selective effect of alcohols upon this pathway...
- Epidermal growth factor-like growth factors prevent apoptosis of alcohol-exposed human placental cytotrophoblast cellsGaren S Wolff
C S Mott Center for Human Growth and Development, Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
Biol Reprod 77:53-60. 2007..These findings reveal the potential for ethanol to rapidly induce cytotrophoblast apoptosis. However, survival factor induction could provide cytotrophoblasts with an endogenous cytoprotective mechanism...