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Limited forward trafficking of connexin 43 reduces cell-cell coupling in stressed human and mouse myocardium.

Gap junctions form electrical conduits between adjacent myocardial cells, permitting rapid spatial passage of the excitation current essential to each heartbeat. Arrhythmogenic decreases in gap junction coupling are a characteristic of stressed, failing, and aging myocardium, but the mechanisms of decreased coupling are poorly understood. We previously found that microtubules bearing gap junction hemichannels (connexons) can deliver their cargo directly to adherens junctions. The specificity of this delivery requires the microtubule plus-end tracking protein EB1. We performed this study to investigate the hypothesis that the oxidative stress that accompanies acute and chronic ischemic disease perturbs connexon forward trafficking. We found that EB1 was displaced in ischemic human hearts, stressed mouse hearts, and isolated cells subjected to oxidative stress. As a result, we observed limited microtubule interaction with adherens junctions at intercalated discs and reduced connexon delivery and gap junction coupling. A point mutation within the tubulin-binding domain of EB1 reproduced EB1 displacement and diminished connexon delivery, confirming that EB1 displacement can limit gap junction coupling. In zebrafish hearts, oxidative stress also reduced the membrane localization of connexin and slowed the spatial spread of excitation. We anticipate that protecting the microtubule-based forward delivery apparatus of connexons could improve cell-cell coupling and reduce ischemia-related cardiac arrhythmias.

Pubmed ID: 20038810


  • Smyth JW
  • Hong TT
  • Gao D
  • Vogan JM
  • Jensen BC
  • Fong TS
  • Simpson PC
  • Stainier DY
  • Chi NC
  • Shaw RM


The Journal of clinical investigation

Publication Data

January 6, 2010

Associated Grants

  • Agency: NHLBI NIH HHS, Id: HL075449
  • Agency: NHLBI NIH HHS, Id: HL094414
  • Agency: NHLBI NIH HHS, Id: HL31113
  • Agency: NHLBI NIH HHS, Id: HL54737
  • Agency: NHLBI NIH HHS, Id: K08 HL075449
  • Agency: NHLBI NIH HHS, Id: K08 HL075449-04
  • Agency: NHLBI NIH HHS, Id: K08 HL075449-05
  • Agency: NHLBI NIH HHS, Id: K08 HL096836
  • Agency: NHLBI NIH HHS, Id: R01 HL094414
  • Agency: NHLBI NIH HHS, Id: R01 HL094414-01A1

Mesh Terms

  • Animals
  • Cell Communication
  • Cell Membrane
  • Connexin 43
  • Female
  • Gap Junctions
  • HeLa Cells
  • Humans
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Microtubule-Associated Proteins
  • Microtubules
  • Myocardial Ischemia
  • Myocardium
  • Oxidative Stress
  • Protein Transport
  • Zebrafish