Mg2+ deprivation elicits rapid Ca2+ uptake and activates Ca2+/calcineurin signaling in Saccharomyces cerevisiae.

Abstract

To learn about the cellular processes involved in Mg(2+) homeostasis and the mechanisms allowing cells to cope with low Mg(2+) availability, we performed RNA expression-profiling experiments and followed changes in gene activity upon Mg(2+) depletion on a genome-wide scale. A striking portion of genes up-regulated under Mg(2+) depletion are also induced by high Ca(2+) and/or alkalinization. Among the genes significantly up-regulated by Mg(2+) starvation, Ca(2+) stress, and alkalinization are ENA1 (encoding a P-type ATPase sodium pump) and PHO89 (encoding a sodium/phosphate cotransporter). We show that up-regulation of these genes is dependent on the calcineurin/Crz1p (calcineurin-responsive zinc finger protein) signaling pathway. Similarly to Ca(2+) stress, Mg(2+) starvation induces translocation of the transcription factor Crz1p from the cytoplasm into the nucleus. The up-regulation of ENA1 and PHO89 upon Mg(2+) starvation depends on extracellular Ca(2+). Using fluorescence resonance energy transfer microscopy, we demonstrate that removal of Mg(2+) results in an immediate increase in free cytoplasmic Ca(2+). This effect is dependent on external Ca(2+). The results presented indicate that Mg(2+) depletion in yeast cells leads to enhanced cellular Ca(2+) concentrations, which activate the Crz1p/calcineurin pathway. We provide evidence that calcineurin/Crz1p signaling is crucial for yeast cells to cope with Mg(2+) depletion stress.

• Authors: Gerlinde Wiesenberger, Katarina Steinleitner, Roland Malli, Wolfgang F Graier, Jürgen Vormann, Rudolf J Schweyen, Jochen A Stadler
• Journal: Eukaryotic cell (Eukaryot Cell) Vol. 6 Issue 4 Pg. 592-9 (Apr 2007) ISSN: 1535-9778 [Print] United States
• PMID: 17337637 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• RNA, Messenger
• Saccharomyces cerevisiae Proteins
• Calcineurin
• Magnesium
• Calcium

Topics

• Calcineurin (metabolism)
• Calcium (metabolism)
• Calcium Signaling (drug effects)
• Cytoplasm (drug effects)
• Food Deprivation
• Gene Expression Regulation, Fungal (drug effects)
• Genome, Fungal (drug effects)
• Magnesium (metabolism, pharmacology)
• RNA, Messenger (genetics, metabolism)
• Saccharomyces cerevisiae (cytology, drug effects, metabolism)
• Saccharomyces cerevisiae Proteins (genetics, metabolism)
• Transcription, Genetic (drug effects)