Altered translation initiation of Gja1 limits gap junction formation during epithelial–mesenchymal transition

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dc.contributor.authorJames, Carissa C.en
dc.contributor.authorZeitz, Michael J.en
dc.contributor.authorCalhoun, Patrick J.en
dc.contributor.authorLamouille, Samy Y.en
dc.contributor.authorSmyth, James W.en
dc.date.accessioned2019-06-03T21:03:07Zen
dc.date.available2019-06-03T21:03:07Zen
dc.date.issued2018-02-13en
dc.description.abstractEpithelial–mesenchymal transition (EMT) is activated during development, wound healing, and pathologies including fibrosis and cancer metastasis. Hallmarks of EMT are remodeling of intercellular junctions and adhesion proteins, including gap junctions. The GJA1 mRNA transcript encoding the gap junction protein connexin43 (Cx43) has been demonstrated to undergo internal translation initiation, yielding truncated isoforms that modulate gap junctions. The PI3K/Akt/mTOR pathway is central to translation regulation and is activated during EMT, leading us to hypothesize that altered translation initiation would contribute to gap junction loss. Using TGF-β–induced EMT as a model, we find reductions in Cx43 gap junctions despite increased transcription and stabilization of Cx43 protein. Biochemical experiments reveal suppression of the internally translated Cx43 isoform, GJA1-20k in a Smad3 and ERK-dependent manner. Ectopic expression of GJA1-20k does not halt EMT, but is sufficient to rescue gap junction formation. GJA1-20k localizes to the Golgi apparatus, and using superresolution localization microscopy we find retention of GJA1-43k at the Golgi in mesenchymal cells lacking GJA1-20k. NativePAGE demonstrates that levels of GJA1-20k regulate GJA1-43k hexamer oligomerization, a limiting step in Cx43 trafficking. These findings reveal alterations in translation initiation as an unexplored mechanism by which the cell regulates Cx43 gap junction formation during EMT.en
dc.description.sponsorshipThis work was supported by National Institutes of Health National Heart, Lung, and Blood Institute (NIH NHLBI) R01 grant HL-132236 (to J.W.S.) and NIH NHLBI F31 grant HL-140909 (to C.C.J.).en
dc.format.extent12 pagesen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.1091/mbc.e17-06-0406en
dc.identifier.issue7en
dc.identifier.urihttp://hdl.handle.net/10919/89722en
dc.identifier.volume29en
dc.language.isoenen
dc.publisherThe American Society for Cell Biologyen
dc.rightsCreative Commons Attribution-Noncommercial-Share Alike 3.0 Unporteden
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/3.0/en
dc.titleAltered translation initiation of Gja1 limits gap junction formation during epithelial–mesenchymal transitionen
dc.title.serialMB0Cen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

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