An osmotically induced cytosolic Ca2+ transient activates calcineurin signaling to mediate ion homeostasis and salt tolerance of Saccharomyces cerevisiae.
Hyperosmotic stress caused by NaCl, LiCl, or sorbitol induces an immediate and short duration ( approximately 1 min) transient cytosolic Ca(2+) ([Ca(2+)](cyt)) increase (Ca(2+)-dependent aequorin luminescence) in Saccharomyces cerevisiae cells. The amplitude of the osmotically induced [Ca(2+)](cyt) transient was attenuated by the addition of chelating agents EGTA or BAPTA, cation channel pore blockers, competitive inhibitors of Ca(2+) transport, or mutations (cch1Delta or mid1Delta) that reduce Ca(2+) influx, indicating that Ca(ext)(2+) is a source for the transient. An osmotic pretreatment (30 min) administered by inoculating cells into media supplemented with either NaCl (0.4 or 0.5 m) or sorbitol (0.8 or 1.0 m) enhanced the subsequent growth of these cells in media containing 1 m NaCl or 2 m sorbitol. Inclusion of EGTA in the osmotic pretreatment media or the cch1Delta mutation reduced cellular capacity for NaCl but not hyperosmotic adaptation. The stress-adaptive effect of hyperosmotic pretreatment was mimicked by exposing cells briefly to 20 mm CaCl(2). Thus, NaCl- or sorbitol-induced hyperosmotic shock causes a [Ca(2+)](cyt) transient that is facilitated by Ca(2+) influx, which enhances ionic but not osmotic stress adaptation. NaCl-induced ENA1 expression was inhibited by EGTA, cch1Delta mutation, and FK506, indicating that the [Ca(2+)](cyt) transient activates calcineurin signaling to mediate ion homeostasis and salt tolerance.
Matsumoto
Tracie K
TK
Center for Plant Environmental Stress Physiology, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, Indiana 47907-1165, USA.
Ellsmore
Amanda J
AJ
Cessna
Stephen G
SG
Low
Philip S
PS
Pardo
José M
JM
Bressan
Ray A
RA
Hasegawa
Paul M
PM
D019703:Calcineurin / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism*; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D007477:Ions; D008954:Models, Biological; D009154:Mutation; D009995:Osmosis; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D012492:Salts / Q000494:pharmacology; D015398:Signal Transduction; D012965:Sodium Chloride / Q000494:pharmacology; D013012:Sorbitol / Q000494:pharmacology; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism
D002614:Chelating Agents; D007477:Ions; D012492:Salts; D012965:Sodium Chloride; D013012:Sorbitol; D004533:Egtazic Acid; D019703:Calcineurin; D001616:beta-Galactosidase; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium