The Novel Nuclear Envelope Protein KAKU4 Modulates Nuclear Morphology in Arabidopsis
The Novel Nuclear Envelope Protein KAKU4 Modulates Nuclear Morphology in Arabidopsis
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DOI：
10.1105/tpc.113.122168
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发表时间：
2014-05-01
期刊：
影响因子：
11.6
通讯作者：
Hara-Nishimura, Ikuko
中科院分区：
文献类型：
--
作者：
Goto, Chieko;Tamura, Kentaro;Hara-Nishimura, Ikuko
在动物中，核纤层是核膜内表面上的纤维网，由卷曲螺旋纤层蛋白和纤层蛋白结合膜蛋白组成。植物在核膜的内表面上也有一个网状结构，但除了存在拥挤核（CRWN）蛋白家族成员（可能的植物核纤层蛋白类似物）外，对其组成知之甚少。在这里，我们描述了一个候选叶片组件，基于两个拟南芥突变体（kaku 2和kaku 4）与异常的核形态。kaku 2中的负责基因编码CRWN 1，kaku 4中的负责基因编码一种功能未知的植物特异性蛋白（KAKU 4），该蛋白与CRWN 1及其同源物CRWN 4相互作用。免疫胶体金标记显示KAKU 4定位于核内膜。KAKU 4以剂量依赖性方式使核膜变形，与核膜内陷和堆叠形成相关。依赖于KAKU 4的核膜变形被CRWN 1的过度积累所增强，尽管即使在CRWN 1和/或CRWN 4不存在的情况下，KAKU 4也可以使核膜变形。总之，这些结果表明，植物已经进化出一种独特的层片状结构来调节核的形状和大小。
In animals, the nuclear lamina is a fibrillar meshwork on the inner surface of the nuclear envelope, composed of coiled-coil lamin proteins and lamin binding membrane proteins. Plants also have a meshwork on the inner surface of the nuclear envelope, but little is known about its composition other than the presence of members of the CROWDED NUCLEI (CRWN) protein family, possible plant lamin analogs. Here, we describe a candidate lamina component, based on two Arabidopsis thaliana mutants (kaku2 and kaku4) with aberrant nuclear morphology. The responsible gene in kaku2 encodes CRWN1, and the responsible gene in kaku4 encodes a plant-specific protein of unknown function (KAKU4) that physically interacts with CRWN1 and its homolog CRWN4. Immunogold labeling revealed that KAKU4 localizes at the inner nuclear membrane. KAKU4 deforms the nuclear envelope in a dose-dependent manner, in association with nuclear membrane invagination and stack formation. The KAKU4-dependent nuclear envelope deformation was enhanced by overaccumulation of CRWN1, although KAKU4 can deform the nuclear envelope even in the absence of CRWN1 and/or CRWN4. Together, these results suggest that plants have evolved a unique lamina-like structure to modulate nuclear shape and size.