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 (Ln(3+)) are used as potent blockers of Ca2+ channels, the systematic studies correlating Ln(3+) accumulation and toxicity to Ca2+ channel blocking activity are scarce. In this study, we made use of the eukaryotic model Saccharomyces cerevisiae to investigate the correlation between Ln(3+) accumulation, their toxicity and their capacity to block the exogenous stress-induced Ca2+ influx into the cytosol. It was found that the Ln(3+) blocked the Ca2+ entry into the yeast cells only when present at concentration high enough to allow rapid binding to cell surface. At lower concentrations, Ln(3+) were taken up by the cell, but Ca2+ blockage was no longer achieved. At 1 mM concentration, all ions from the Ln(3+) series could block Ca2+ entry into cytosol with the exception of La3+, and to a lesser extent, Pr3+ and Nd3+. The plasma membrane Ca2+-channel Cch1/Mid1 contributed to La3+ and Gd3+ entry into the cells, with a significant preference for La3+. The results open the possibility to obtain cells loaded with controlled amounts and ratios of Ln(3+).