Manganese Suppresses the Haploinsufficiency of Heterozygous trpy1Δ/TRPY1Saccharomyces cerevisiae Cells and Stimulates the TRPY1-Dependent Release of Vacuolar Ca2+ under H₂O₂ Stress.

Lavinia Ruta,Ileana Farcasanu,Claudia Popa,Ioana Nicolau

doi:10.3390/cells8020079

Abstract

Transient potential receptor (TRP) channels are conserved cation channels found in most eukaryotes, known to sense a variety of chemical, thermal or mechanical stimuli. The Saccharomyces cerevisiae TRPY1 is a TRP channel with vacuolar localization involved in the cellular response to hyperosmotic shock and oxidative stress. In this study, we found that S. cerevisiae diploid cells with heterozygous deletion in TRPY1 gene are haploinsufficient when grown in synthetic media deficient in essential metal ions and that this growth defect is alleviated by non-toxic Mn2+ surplus. Using cells expressing the Ca2+-sensitive photoprotein aequorin we found that Mn2+ augmented the Ca2+ flux into the cytosol under oxidative stress, but not under hyperosmotic shock, a trait that was absent in the diploid cells with homozygous deletion of TRPY1 gene. TRPY1 activation under oxidative stress was diminished in cells devoid of Smf1 (the Mn2+-high-affinity plasma membrane transporter) but it was clearly augmented in cells lacking Pmr1 (the endoplasmic reticulum (ER)/Golgi located ATPase responsible for Mn2+ detoxification via excretory pathway). Taken together, these observations lead to the conclusion that increased levels of intracytosolic Mn2+ activate TRPY1 in the response to oxidative stress.

Highlights

Living cells are continuously exposed to various changes that threaten the dynamic equilibrium associated with the steady state of homeostatic balance
TRPY1 is necessary for attaining a maximum level of [Ca2+ ]cyt under oxidative stress and TRPY1 depends on [Ca2+ ]cyt elevation for maximal gating, in a process known as Ca2+ -induced Ca2+ release [34]
Haploinsufficiency of Yeast Strain Heterozyous for TRPY1 Is Alleviated by Mn2+

Summary

Introduction

Living cells are continuously exposed to various changes that threaten the dynamic equilibrium associated with the steady state of homeostatic balance. Such changes—often induced by stress agents—need to be sensed and signaled by cell components which belong to intricate networks responsible for homeostatic regulation. The S. cerevisiae cells respond to such stresses by a sudden increase in cytosolic Ca2+ —denoted [Ca2+ ]cyt —following the stimulus-dependent opening of Ca2+ channels situated in the plasma membrane and/or in internal compartments.

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