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Open AccessArticle

Apoptotic Fragmentation of Tricellulin

Department of Biochemistry II, Jena University Hospital, Friedrich Schiller University Jena, 07743 Jena, Germany
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Author to whom correspondence should be addressed.
Int. J. Mol. Sci. 2019, 20(19), 4882; https://doi.org/10.3390/ijms20194882
Received: 26 July 2019 / Revised: 25 September 2019 / Accepted: 26 September 2019 / Published: 1 October 2019
(This article belongs to the Special Issue The Tight Junction and Its Proteins: More Than Just a Barrier)
Apoptotic extrusion of cells from epithelial cell layers is of central importance for epithelial homeostasis. As a prerequisite cell–cell contacts between apoptotic cells and their neighbors have to be dissociated. Tricellular tight junctions (tTJs) represent specialized structures that seal polarized epithelial cells at sites where three cells meet and are characterized by the specific expression of tricellulin and angulins. Here, we specifically addressed the fate of tricellulin in apoptotic cells. Methods: Apoptosis was induced by staurosporine or camptothecin in MDCKII and RT-112 cells. The fate of tricellulin was analyzed by Western blotting and immunofluorescence microscopy. Caspase activity was inhibited by Z-VAD-FMK or Z-DEVD-FMK. Results: Induction of apoptosis induces the degradation of tricellulin with time. Aspartate residues 487 and 441 were identified as caspase cleavage-sites in the C-terminal coiled-coil domain of human tricellulin. Fragmentation of tricellulin was inhibited in the presence of caspase inhibitors or when Asp487 or Asp441 were mutated to asparagine. Deletion of the tricellulin C-terminal amino acids prevented binding to lipolysis-stimulated lipoprotein receptor (LSR)/angulin-1 and thus should impair specific localization of tricellulin to tTJs. Conclusions: Tricellulin is a substrate of caspases and its cleavage in consequence contributes to the dissolution of tTJs during apoptosis. View Full-Text
Keywords: tight junction; tricellulin; lipolysis-stimulated lipoprotein receptor (LSR); angulin; epithelial barrier; cell–cell contact; apoptosis; caspase tight junction; tricellulin; lipolysis-stimulated lipoprotein receptor (LSR); angulin; epithelial barrier; cell–cell contact; apoptosis; caspase
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MDPI and ACS Style

Janke, S.; Mittag, S.; Reiche, J.; Huber, O. Apoptotic Fragmentation of Tricellulin. Int. J. Mol. Sci. 2019, 20, 4882.

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