SUMOylation regulates the intracellular fate of ZO-2

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• 作者：Franziska Wetzel ; Sonnhild Mittag…
• 关键词：Tight junction ; Zonula occludens ; 2 ; β ; Catenin ; Glycogen ; synthase ; kinase ; 3β ; Occludin
• 刊名：Cellular and Molecular Life Sciences
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：74
• 期：2
• 页码：373-392
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Cell Biology; Biomedicine, general; Life Sciences, general; Biochemistry, general;
• 出版者：Springer International Publishing
• ISSN：1420-9071
• 卷排序：74

文摘

The zonula occludens (ZO)-2 protein links tight junctional transmembrane proteins to the actin cytoskeleton and associates with splicing and transcription factors in the nucleus. Multiple posttranslational modifications control the intracellular distribution of ZO-2. Here, we report that ZO-2 is a target of the SUMOylation machinery and provide evidence on how this modification may affect its cellular distribution and function. We show that ZO-2 associates with the E2 SUMO-conjugating enzyme Ubc9 and with SUMO-deconjugating proteases SENP1 and SENP3. In line with this, modification of ZO-2 by endogenous SUMO1 was detectable. Ubc9 fusion-directed SUMOylation confirmed SUMOylation of ZO-2 and was inhibited in the presence of SENP1 but not by an enzymatic-dead SENP1 protein. Moreover, lysine 730 in human ZO-2 was identified as a potential modification site. Mutation of this site to arginine resulted in prolonged nuclear localization of ZO-2 in nuclear recruitment assays. In contrast, a construct mimicking constitutive SUMOylation of ZO-2 (SUMO1ΔGG-ZO-2) was preferentially localized in the cytoplasm. Based on previous findings the differential localization of these ZO-2 constructs may affect glycogen-synthase-kinase-3β (GSK3β) activity and β-catenin/TCF-4-mediated transcription. In this context we observed that ZO-2 directly binds to GSK3β and SUMO1ΔGG-ZO-2 modulates its kinase activity. Moreover, we show that ZO-2 forms a complex with β-catenin. Wild-type ZO-2 and ZO-2-K730R inhibited transcriptional activity in reporter gene assays, whereas the cytosolic SUMO1ΔGG-ZO-2 did not. From these data we conclude that SUMOylation affects the intracellular localization of ZO-2 and its regulatory role on GSK3β and β-catenin signaling activity.