Homocysteine enhances cardiac neural crest cell attachment in vitro by increasing intracellular calcium levels

Elevated homocysteine (Hcys) increases the risk of neurocristopathies. Previous studies show Hcys inhibits neural crest (NC) cell migration in vivo. However, the mechanisms responsible for this effect are unknown. Here, we evaluated the effect of Hcys on NC cell attachment in vitro and determined if any of the effects were due to altered Ca2+ signaling. We found Hcys enhanced NC cell attachment in a dose and substrate-dependent manner. Ionomycin mimicked the effect of Hcys while BAPTA-AM and 2-APB blocked the effect of Hcys on NC attachment. In contrast, inhibitors of plasma membrane Ca2+ channels had no effect on NC attachment. Hcys also increased the emission of the intracellular Ca2+-sensitive probe, Fluo-4. These results show Hcys alters NC attachment by triggering an increase in intracellular Ca2+ possibly by generating inositol triphosphate. Hence, the teratogenic effect ascribed to Hcys may be due to perturbation of intracellular Ca2+ signaling.