Effects of alcohol, lithium, and homocysteine on nonmuscle myosin-II in the mouse placenta and human trophoblasts.

OBJECTIVE: Mouse embryonic exposure to alcohol, lithium, and homocysteine results in intrauterine growth restriction (IUGR) and cardiac defects. Our present study focused on the placental effects. We analyzed the hypothesis that expression of nonmuscle myosin (NMM)-II isoforms involved in cell motility, mechanosensing, and extracellular matrix assembly are altered by the 3 factors in human trophoblast (HTR8/SVneo) cells in vitro and in the mouse placenta in vivo. STUDY DESIGN: After exposure during gastrulation to alcohol, homocysteine, or lithium, ultrasonography defined embryos exhibiting abnormal placental blood flow. RESULTS: NMM-IIA/NMM-IIB are differentially expressed in trophoblasts and in mouse placental vascular endothelial cells under pathological conditions. Misexpression of NMM-IIA/NMM-IIB in the affected placentas continued stably to midgestation but can be prevented by folate and myoinositol supplementation. CONCLUSION: It is concluded that folate and myoinositol initiated early in mouse pregnancy can restore NMM-II expression, permit normal placentation/embryogenesis, and prevent IUGR induced by alcohol, lithium, and homocysteine.

Fetal alcohol syndrome: cardiac birth defects in mice and prevention with folate.

OBJECTIVE: Alcohol (ethanol) consumption during pregnancy is linked to congenital heart defects that are associated with fetal alcohol syndrome. Recent reports have associated ethanol exposure with the Wnt/beta-catenin pathway. Therefore, we defined whether ethanol affects Wnt/beta-catenin signaling during cardiac cell specification. STUDY DESIGN: Pregnant mice on embryonic day 6.75 during gastrulation were exposed by an intraperitoneal injection to a binge-drinking dose of ethanol. Folic acid supplementation of mouse diet was tested for the prevention of ethanol-induced cardiac birth defects. RESULTS: Acute ethanol exposure induced myocardial wall changes and atrioventricular and semilunar valve defects, which was determined by echocardiography on embryonic day 15.5. A high folate diet prevented the ethanol-induced cardiac defects. Ethanol exposure in avian embryos suppressed 2 key Wnt-modulated genes that are involved in cardiac induction; folic acid rescued normal gene expression. CONCLUSION: Folic acid supplementation alone or with myoinositol prevented alcohol potentiation of Wnt/beta-catenin signaling that allowed normal gene activation and cardiogenesis.

Folate rescues lithium-, homocysteine- and Wnt3A-induced vertebrate cardiac anomalies.

Elevated plasma homocysteine (HCy), which results from folate (folic acid, FA) deficiency, and the mood-stabilizing drug lithium (Li) are both linked to the induction of human congenital heart and neural tube defects. We demonstrated previously that acute administration of Li to pregnant mice on embryonic day (E)6.75 induced cardiac valve defects by potentiating Wnt-beta-catenin signaling. We hypothesized that HCy may similarly induce cardiac defects during gastrulation by targeting the Wnt-beta-catenin pathway. Because dietary FA supplementation protects from neural tube defects, we sought to determine whether FA also protects the embryonic heart from Li- or HCy-induced birth defects and whether the protection occurs by impacting Wnt signaling. Maternal elevation of HCy or Li on E6.75 induced defective heart and placental function on E15.5, as identified non-invasively using echocardiography. This functional analysis of HCy-exposed mouse hearts revealed defects in tricuspid and semilunar valves, together with altered myocardial thickness. A smaller embryo and placental size was observed in the treated groups. FA supplementation ameliorates the observed developmental errors in the Li- or HCy-exposed mouse embryos and normalized heart function. Molecular analysis of gene expression within the avian cardiogenic crescent determined that Li, HCy or Wnt3A suppress Wnt-modulated Hex (also known as Hhex) and Islet-1 (also known as Isl1) expression, and that FA protects from the gene misexpression that is induced by all three factors. Furthermore, myoinositol with FA synergistically enhances the protective effect. Although the specific molecular epigenetic control mechanisms remain to be defined, it appears that Li or HCy induction and FA protection of cardiac defects involve intimate control of the canonical Wnt pathway at a crucial time preceding, and during, early heart organogenesis.