The Mechanism of Cell Cycle Arrest Front Progression Explained by a KLUH/CYP78A5-dependent Mobile Growth Factor in Developing Leaves of Arabidopsis thaliana
The Mechanism of Cell Cycle Arrest Front Progression Explained by a KLUH/CYP78A5-dependent Mobile Growth Factor in Developing Leaves of Arabidopsis thaliana
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DOI：
10.1093/pcp/pcq051
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发表时间：
2010-06-01
影响因子：
4.9
通讯作者：
Tsukaya, Hirokazu
中科院分区：
文献类型：
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作者：
Kazama, Toshiya;Ichihashi, Yasunori;Tsukaya, Hirokazu
叶片的大小和形状受到细胞周期停滞前沿(AF)进程的影响。然而，AF随叶片生长的进程还没有得到定量的描述。此外，房颤的进展与遗传因素之间的联系机制还不完全清楚。最近，有人提出依赖于Kluh/CyP78A5(Klu)的信号作为细胞增殖的移动生长因子(MGF)来控制拟南芥的侧器官大小。本研究在假设依赖于Klu的MGF的梯度场动力学提供了房颤进展的机制的假设下，使用分子标记和计算机模拟来检验这一假说。首先，我们使用pCYCB1；1：：CYCB1；1：：GUS表达模式测量了随着叶片生长而准确的AF位置，该模式可以可视化有丝分裂细胞。结果，我们发现，AF保持在与叶片基部几乎恒定的距离(阶段1)，然后向叶片底部进发，并相对较快地消失(阶段2)，这是以前没有发现的。其次，通过比较pKLU：：GUS和pCYCB1；1：：CYCB1；1：：CYCB1；1：：GUS的表达模式，我们发现，如果KLU确实通过MGF的生物合成来控制细胞分裂，那么KLU可能会在叶片中产生MGF的浓度梯度。最后，我们使用一个带有衰变项的扩散方程建立了一个模拟模型，其中边界条件中包含了从Klu表达式水平估计的MGF产生率。我们的模拟模型成功地再现了房颤的第一阶段和第二阶段，表明所提出的机制确实解释了在某些限制条件下的房颤进展。
The size and shape of leaves are influenced by the progression of the cell cycle arrest front (AF). However, the AF progression with leaf growth has not been characterized quantitatively. Moreover, the mechanism linking AF progression and genetic factors is not fully understood. Recently, it was proposed that a KLUH/CYP78A5 (KLU)-dependent signal acts as a mobile growth factor (MGF) for cell proliferation and controls the lateral organ size of Arabidopsis. This study examines this hypothesis under the assumption that the gradient field dynamics of the KLU-dependent MGF provide the mechanism of AF progression using molecular markers and computer simulations. First, we measured the exact AF position with leaf growth using the pCYCB1;1::CYCB1;1::GUS expression pattern, which visualizes mitotic cells. As a result, we found that the AF stayed at an almost constant distance from the leaf blade base (stage 1) and then progressed towards the base and disappeared relatively quickly (stage 2), which previously had not been identified. Secondly, we showed that KLU may generate a concentration gradient of MGF in leaves, if KLU really controls cell division via the biosynthesis of MGF, by comparing the expression patterns of pKLU::GUS and pCYCB1;1::CYCB1;1::GUS. Finally, we built a simulation model using a diffusion equation with a decay term, in which the rate of MGF production estimated from the KLU expression level was included in the boundary condition. Our simulation model successfully reproduced both stages 1 and 2 of the AF, suggesting that the proposed mechanism does explain the AF progression under some restricted conditions.