Altered translation initiation ofGja1limits gap junction formation during epithelial–mesenchymal transition

• DOI: 10.1091/mbc.e17-06-0406
• Publication Date: 2018-02-21T17:10:49Z
• Authors: Carissa C. James; Michael J. Zeitz; Patrick J. Calhoun; Samy Lamouille; James W. Smyth
• Keywords: 0301 basic medicine; 0303 health sciences; 03 medical and health sciences; Articles

Epithelial–mesenchymal transition (EMT) is activated during development, wound healing, and pathologies including fibrosis cancer metastasis. Hallmarks of EMT are remodeling intercellular junctions adhesion proteins, gap junctions. The GJA1 mRNA transcript encoding the junction protein connexin43 (Cx43) has been demonstrated to undergo internal translation initiation, yielding truncated isoforms that modulate PI3K/Akt/mTOR pathway central regulation EMT, leading us hypothesize altered initiation would contribute loss. Using TGF-β–induced as a model, we find reductions in Cx43 despite increased transcription stabilization protein. Biochemical experiments reveal suppression internally translated isoform, GJA1-20k Smad3 ERK-dependent manner. Ectopic expression does not halt but sufficient rescue formation. localizes Golgi apparatus, using superresolution localization microscopy retention GJA1-43k at mesenchymal cells lacking GJA1-20k. NativePAGE demonstrates levels regulate hexamer oligomerization, limiting step trafficking. These findings alterations an unexplored mechanism by which cell regulates formation EMT.