Nuclear membranes control symbiotic calcium signaling of legumes
Nuclear membranes control symbiotic calcium signaling of legumes
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DOI：
10.1073/pnas.1107912108
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发表时间：
2011-08-23
影响因子：
11.1
通讯作者：
Oldroyd, Giles E. D.
中科院分区：
文献类型：
--
作者：
Capoen, Ward;Sun, Jongho;Oldroyd, Giles E. D.
钙离子的核相关振荡在豆科植物的共生信号通路中扮演第二信使的角色。这些是由核定位的钙和钙调蛋白依赖的蛋白激酶解码的，其激活足以驱动下游反应。这意味着细胞核内的钙振荡是豆科植物共生的主要信号。然而，允许核区靶向释放钙的机制尚未确定。在这里，我们表明，共生引起的钙变化发生在核质和核周细胞质，似乎起源于核膜。反应扩散模拟表明，核质内尖峰的产生不可能仅通过细胞质的钙波传递，而且钙很可能通过核内膜释放出来，从而允许核钙的变化。与此一致，我们发现对共生钙振荡至关重要的阳离子通道DMI1优先位于内核膜上，这意味着内核膜在共生钙信号中具有重要的功能。此外，共生钙振荡所必需的肌浆/内质网钙ATPase(SERCA)定位于内核膜、外核膜和内质网(ER)。我们认为，跨内核膜的钙释放允许内质网钙库的靶向释放，而这种钙库的有效重新加载需要从核浆和核相关细胞质中捕获钙。
Nuclear-associated oscillations in calcium act as a secondary messenger in the symbiotic signaling pathway of legumes. These are decoded by a nuclear-localized calcium and calmodulin-dependent protein kinase, the activation of which is sufficient to drive downstream responses. This implies that the calcium oscillations within the nucleus are the predominant signals for legume symbiosis. However, the mechanisms that allow targeted release of calcium in the nuclear region have not been defined. Here we show that symbiosis-induced calcium changes occur in both the nucleoplasm and the perinuclear cytoplasm and seem to originate from the nuclear membranes. Reaction diffusion simulations suggest that spike generation within the nucleoplasm is not possible through transmission of a calcium wave from the cytoplasm alone and that calcium is likely to be released across the inner nuclear membrane to allow nuclear calcium changes. In agreement with this, we found that the cation channel DMI1, which is essential for symbiotic calcium oscillations, is preferentially located on the inner nuclear membrane, implying an essential function for the inner nuclear membrane in symbiotic calcium signaling. Furthermore, a sarco/endoplasmic reticulum calcium ATPase (SERCA) essential for symbiotic calcium oscillations is targeted to the inner nuclear membrane, as well as the outer nuclear membrane and endoplasmic reticulum (ER). We propose that release of calcium across the inner nuclear membrane allows targeted release of the ER calcium store, and efficient reloading of this calcium store necessitates the capture of calcium from the nucleoplasm and nuclear-associated cytoplasm.