Differential regulation of two Ca(2+) influx systems by pheromone signaling in Saccharomyces cerevisiae.
Differential regulation of two Ca(2+) influx systems by pheromone signaling in Saccharomyces cerevisiae.
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发表时间：
2001-12
期刊：
影响因子：
3.3
通讯作者：
Eric M. Muller;Emily G. Locke;Kyle W. Cunningham
中科院分区：
文献类型：
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作者：
Eric M. Muller;Emily G. Locke;Kyle W. Cunningham
出芽酵母酿酒酵母在响应交配信息素时产生钙信号，促进未交配细胞的存活。由Cch1p和Mid1p组成的Ca（2+）通道先前被证明是产生这些钙信号所必需的。然而，我们发现Cch1p-Mid1p高亲和Ca（2+）内流系统（HACS）在富媒体α -因子治疗后对信号传导或存活的贡献很小。钙调神经磷酸酶失活或抑制后HACS活性明显增强，提示Cch1p-Mid1p Ca（2+）通道受钙调神经磷酸酶直接或间接调控。相反，富培养基中信息素信号刺激了明显的低亲和力Ca（2+）内流系统（LACS）。LACS活性对钙调磷酸酶活性不敏感，不依赖于Cch1p和Mid1p，足以提高胞内游离Ca（2+）浓度（[Ca(2+)]c），尽管其对Ca（2+）的亲和力低16倍。在dig1 dig2双突变体中，Ste12p的过表达或该转录因子的组成性激活对LACS活性没有影响，但在钙调磷酸酶失活的情况下，会刺激HACS活性。Ste12p激活对Cch1p或Mid1p丰度没有影响，这表明Ste12p的另一个靶点参与了HACS刺激。即使在dig1、dig2双突变体中，激活LACS也需要交配信息素处理，还需要FAR1、SPA2和BNI1，这是适当的细胞周期阻滞和极化形态发生所必需的。这些结果表明，信息素信号通路的不同分支独立调节HACS和LACS的活性，它们中的任何一个都可以促进长期反应中的生存。
The budding yeast Saccharomyces cerevisiae generates calcium signals during the response to mating pheromones that promote survival of unmated cells. A Ca(2+) channel composed of Cch1p and Mid1p was previously shown to be necessary for the production of these calcium signals. However, we find that the Cch1p-Mid1p high-affinity Ca(2+) influx system (HACS) contributes very little to signaling or survival after treatment with alpha-factor in rich media. HACS activity was much greater after calcineurin inactivation or inhibition, suggesting the Cch1p-Mid1p Ca(2+) channel is subject to direct or indirect regulation by calcineurin. Instead a distinct low-affinity Ca(2+) influx system (LACS) was stimulated by pheromone signaling in rich medium. LACS activity was insensitive to calcineurin activity, independent of Cch1p and Mid1p, and sufficient to elevate cytosolic free Ca(2+) concentrations ([Ca(2+)]c) in spite of its 16-fold lower affinity for Ca(2+). Overexpression of Ste12p or constitutive activation of this transcription factor in dig1 dig2 double mutants had no effect on LACS activity but stimulated HACS activity when calcineurin was also inactivated. Ste12p activation had no effect on Cch1p or Mid1p abundance, suggesting the involvement of another target of Ste12p in HACS stimulation. LACS activation required treatment with mating pheromone even in dig1 dig2 double mutants and also required FAR1, SPA2, and BNI1, which are necessary for proper cell cycle arrest and polarized morphogenesis. These results show that distinct branches of the pheromone-signaling pathway independently regulate HACS and LACS activities, either of which can promote survival during long-term responses.