Shank2 Binds to aPKC and Controls Tight Junction Formation with Rap1 Signaling during Establishment of Epithelial Cell Polarity
Shank2 Binds to aPKC and Controls Tight Junction Formation with Rap1 Signaling during Establishment of Epithelial Cell Polarity
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DOI：
10.1016/j.celrep.2020.02.088
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发表时间：
2020-04-07
期刊：
影响因子：
8.8
通讯作者：
Ohno，Shigeo
中科院分区：
文献类型：
--
作者：
Sasaki，Kazunori;Kojitani，Noriko;Ohno，Shigeo
上皮细胞通过在顶侧边界形成紧密连接（TJs）来建立顶底极性，在生理功能中起着重要作用。一种进化上保守的非典型蛋白激酶C（aPKC）-分配缺陷（PAR）复合物在细胞极性建立期间作为TJ组装的平台发挥作用。然而，这种复合体如何将空间线索转化为随后的活动单位尚不清楚。在这里，我们确定了上皮亚型的Shank 2作为中介的aPKC-PAR复合物。Shank 2与极化上皮细胞的顶端连接区的aPKC结合并共定位。Shank 2敲低导致TJ形成中的缺陷。从机制上讲，我们发现N-末端SPN结构域是Shank 2的连接定位所需的，并与参与TJ形成的Rap 1小GTdR的活性形式结合。我们的研究结果表明，一个密切的物理和功能之间的关系aPKC和Shank 2活性Rap 1信号作为平台的TJ组装，以调节上皮细胞极性。
Epithelial cells establish apicobasal polarity by forming tight junctions (TJs) at the apical-lateral boundary, which play fundamental roles in physiological functions. An evolutionarily conserved atypical protein kinase C (aPKC)-partitioning defective (PAR) complex functions as a platform for TJ assembly during cell polarity establishment. However, how this complex converts the spatial cues into a subsequent active unit is unclear. Here, we identify an epithelial isoform of Shank2 as a mediator of the aPKC-PAR complex. Shank2 binds to and colocalizes with aPKC at apical junctional regions of polarized epithelial cells. Shank2 knockdown results in defects in TJ formation. Mechanistically, we find that the N-terminal SPN domain is required for the junctional localization of Shank2 and binds to the active form of Rap1 small GTPase, which is involved in TJ formation. Our findings suggest that a close physical and functional relationship between aPKC and Shank2-active Rap1 signaling serves as the platform for TJ assembly to regulate epithelial cell polarity.