The E3 ubiquitin ligase NEDD4 induces endocytosis and lysosomal sorting of connexin 43 to promote loss of gap junctions

J Cell Sci. 2017 Sep 1;130(17):2867-2882. doi: 10.1242/jcs.202408. Epub 2017 Jul 21.


Intercellular communication via gap junctions has an important role in controlling cell growth and in maintaining tissue homeostasis. Connexin 43 (Cx43; also known as GJA1) is the most abundantly expressed gap junction channel protein in humans and acts as a tumor suppressor in multiple tissue types. Cx43 is often dysregulated at the post-translational level during cancer development, resulting in loss of gap junctions. However, the molecular basis underlying the aberrant regulation of Cx43 in cancer cells has remained elusive. Here, we demonstrate that the oncogenic E3 ubiquitin ligase NEDD4 regulates the Cx43 protein level in HeLa cells, both under basal conditions and in response to protein kinase C activation. Furthermore, overexpression of NEDD4, but not a catalytically inactive form of NEDD4, was found to result in nearly complete loss of gap junctions and increased lysosomal degradation of Cx43 in both HeLa and C33A cervical carcinoma cells. Collectively, the data provide new insights into the molecular basis underlying the regulation of gap junction size and represent the first evidence that an oncogenic E3 ubiquitin ligase promotes loss of gap junctions and Cx43 degradation in human carcinoma cells.

Keywords: Cancer; Connexin; Degradation; Gap junction; NEDD4; Ubiquitin.

MeSH terms

  • Connexin 43 / metabolism*
  • Endocytosis* / drug effects
  • Endosomes / metabolism
  • Endosomes / ultrastructure
  • Gap Junctions / drug effects
  • Gap Junctions / metabolism*
  • Gap Junctions / ultrastructure
  • HeLa Cells
  • Humans
  • Lysosomes / metabolism*
  • Lysosomes / ultrastructure
  • Nedd4 Ubiquitin Protein Ligases / metabolism*
  • Protein Kinase C / metabolism
  • Proteolysis / drug effects
  • Tetradecanoylphorbol Acetate / pharmacology
  • Ubiquitination / drug effects


  • Connexin 43
  • Nedd4 Ubiquitin Protein Ligases
  • Nedd4 protein, human
  • Protein Kinase C
  • Tetradecanoylphorbol Acetate