Homocysteine and Cardiac Neural Crest Cell Cytoskeletal Proteins in the Chick Embryo

Elevated serum homocysteine (Hcys) is correlated with cardiovascular disease and with embryonic
malformations related to neural crest cells (NCCs). We predicted Hcys may alter the balance of actin networks,
stress fibers and focal adhesions, altering migration. We cultured neural tube explants in control and Hcys-treated
medium and visualized actin, ?-actinin, vinculin, filamin, and LIM3 protein in NCCs migrating outward. In Hcys,
phalloidin-stained actin in stress fibers was brighter, and vinculin was more abundant in focal adhesions and
lamellipodia. ?-actinin and LIM3 were also enhanced around nuclei and in focal adhesions, and ?-actinin also in
filopodia. Filamin was unchanged. Hcys caused more spreading and migration of NCCs, but not more cell-cell
adhesions. The findings support our hypothesis that Hcys adjusts NCCs for greater adhesion and migration. Its
effect on LIM3 suggests it may modulate signaling that adjusts the cytoskeleton for enhanced migration, leading
to mistimed and defective development of target tissues.