Interaction between lanthanide ions and Saccharomyces cerevisiae cells.

Lanthanides are a group of non-essential elements with important imaging and therapeutic applications. Although trivalent lanthanide ions (Ln³âº) are used as potent blockers of Ca²âº channels, the systematic studies correlating Ln³âº accumulation and toxicity to Ca²âº channel blocking activity are scarce. In this study, we made use of the eukaryotic model Saccharomyces cerevisiae to investigate the correlation between Ln³âº accumulation, their toxicity and their capacity to block the exogenous stress-induced Ca²âº influx into the cytosol. It was found that the Ln³âº blocked the Ca²âº entry into the yeast cells only when present at concentration high enough to allow rapid binding to cell surface. At lower concentrations, Ln³âº were taken up by the cell, but Ca²âº blockage was no longer achieved. At 1 mM concentration, all ions from the Ln³âº series could block Ca²âº entry into cytosol with the exception of La³âº, and to a lesser extent, Pr³âº and Nd³âº. The plasma membrane Ca²âº-channel Cch1/Mid1 contributed to La³âº and Gd³âº entry into the cells, with a significant preference for La³âº. The results open the possibility to obtain cells loaded with controlled amounts and ratios of Ln³âº.