The involvement of calcium carriers and of the vacuole in the glucose-induced calcium signaling and activation of the plasma membrane H+-ATPase in Saccharomyces cerevisiae cells

Abstract

Previous work from our laboratories demonstrated that the sugar-induced activation of plasma membrane H(+)-ATPase in Saccharomyces cerevisiae is dependent on calcium metabolism with the contribution of calcium influx from external medium. Our results demonstrate that a glucose-induced calcium (GIC) transporter, a new and still unidentified calcium carrier, sensitive to nifedipine and gadolinium and activated by glucose addition, seems to be partially involved in the glucose-induced activation of the plasma membrane H(+)-ATPase. On the other hand, the importance of calcium carriers that can release calcium from internal stores was analyzed in glucose-induced calcium signaling and activation of plasma membrane H(+)-ATPase, in experimental conditions presenting very low external calcium concentrations. Therefore the aim was also to investigate how the vacuole, through the participation of both Ca(2+)-ATPase Pmc1 and the TRP homologue calcium channel Yvc1 (respectively, encoded by the genes PMC1 and YVC1) contributes to control the intracellular calcium availability and the plasma membrane H(+)-ATPase activation in response to glucose. In strains presenting a single deletion in YVC1 gene or a double deletion in YVC1 and PMC1 genes, both glucose-induced calcium signaling and activation of the H(+)-ATPase are nearly abolished. These results suggest that Yvc1 calcium channel is an important component of this signal transduction pathway activated in response to glucose addition. We also found that by a still undefined mechanism Yvc1 activation seems to correlate with the changes in the intracellular level of IP(3). Taken together, these data demonstrate that glucose addition to yeast cells exposed to low external calcium concentrations affects calcium uptake and the activity of the vacuolar calcium channel Yvc1, contributing to the occurrence of calcium signaling connected to plasma membrane H(+)-ATPase activation.

Hypotonic stress-induced calcium signaling in Saccharomyces cerevisiae involves TRP-like transporters on the endoplasmic reticulum membrane

“…The Yeast Vacuolar Channel, Yvc1, is a homolog of the constitutively active inwardly rectifying calcium channels in mammals known as TRP (Transient Receptor Potential) channels, and likely represents a calcium-activated calcium channel, which has been shown to release Ca 2+ from the vacuole into the cytosol in response to hyperosmotic shock both by mechanical activation and Ca 2+ -induced calcium release [37]. Furthermore, a role was previously proposed for Yvc1 in glucose refeeding-induced calcium signaling [38].…”

Regulation of Cation Balance inSaccharomyces cerevisiae

“…Further studies showed that the Yvc1-encoded channel is mechanosensitive, suggesting that vacuolar shrinkage during osmotic shock may directly activate the channel (Zhou et al 2003). Yvc1 is also thought to contribute to Ca 2+ transients observed after glucose readdition to starved cells (Bouillet et al 2012), although the mechanism of its activation is unknown.…”

“…Ptk2 and Hrk1, members of the Npr1 family of protein kinases, which regulates multiple membrane transporters, are thought to phosphorylate Pma1 (Goossens et al 2000;Eraso et al 2006), and it may be dephosphorylated by a PP1-type phosphatase, containing the Glc7 catalytic subunit (Williams-Hart et al 2002). Other studies suggest that Ca 2+ -dependent signaling also contributes to activation of Pma1, by unknown mechanisms, in response to glucose addition (Tropia et al 2006;Bouillet et al 2012).…”

“…It is IP 3 that is required for Ca 2+ influx, which occurs through two different influx pathways: Mid1/Cch1 and GIC (discussed earlier) (Tisi et al 2004). The mechanism by which IP 3 stimulates these influx pathways has not yet been determined; however, the Ca 2+ signal generated may regulate Pma1 (Tropia et al 2006;Bouillet et al 2012) and is sufficient to activate calcineurin/Crz1 signaling, suggesting a role for this pathway, which up-regulates the expression of several genes encoding carbohydrate-metabolizing enzymes, in the glucose response (Ruiz et al 2008;Groppi et al 2011). …”

Class C ABC transporters andSaccharomyces cerevisiaevacuole fusion

“…It is possible that the absence of Ybt1 from a putative trimeric complex could destabilize the Pmc1-Nyv1 interaction and lead to facile trans-SNARE pairing and more efficient fusion. Others have found that Pmc1 and Yvc1 are both required for the uptake of extracellular Ca 2C during glucose induced Ca 2C signaling, 67 suggesting that the intake and efflux of vacuolar Ca 2C is interdependent. Yvc1 is a homolog of the TRPC family, which can be regulated through mechanical and osmotic stress.…”