Cingulin binds to the ZU5 domain of scaffolding protein ZO-1 to promote its extended conformation, stabilization, and tight junction accumulation.
J Biol Chem 2022;
298:101797. [PMID:
35259394 PMCID:
PMC9010756 DOI:
10.1016/j.jbc.2022.101797]
[Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 12/17/2022] Open
Abstract
Zonula occludens-1 (ZO-1), the major scaffolding protein of tight junctions (TJs), recruits the cytoskeleton-associated proteins cingulin (CGN) and paracingulin (CGNL1) to TJs by binding to their N-terminal ZO-1 interaction motif. The conformation of ZO-1 can be either folded or extended, depending on cytoskeletal tension and intramolecular and intermolecular interactions, and only ZO-1 in the extended conformation recruits the transcription factor DbpA to TJs. However, the sequences of ZO-1 that interact with CGN and CGNL1 and the role of TJ proteins in ZO-1 TJ assembly are not known. Here, we used glutathione-S-transferase pulldowns and immunofluorescence microscopy to show that CGN and CGNL1 bind to the C-terminal ZU5 domain of ZO-1 and that this domain is required for CGN and CGNL1 recruitment to TJs and to phase-separated ZO-1 condensates in cells. We show that KO of CGN, but not CGNL1, results in decreased accumulation of ZO-1 at TJs. Furthermore, ZO-1 lacking the ZU5 domain showed decreased accumulation at TJs, was detectable along lateral contacts, had a higher mobile fraction than full-length ZO-1 by fluorescence recovery after photobleaching analysis, and had a folded conformation, as determined by structured illumination microscopy of its N-terminal and C-terminal ends. The CGN–ZU5 interaction promotes the extended conformation of ZO-1, since binding of the CGN–ZO-1 interaction motif region to ZO-1 resulted in its interaction with DbpA in cells and in vitro. Together, these results show that binding of CGN to the ZU5 domain of ZO-1 promotes ZO-1 stabilization and accumulation at TJs by promoting its extended conformation.
Collapse