Promotion of lens epithelial-fiber differentiation by the C-terminus of connexin 45.6 - A role independent of gap junction communication

Eric A. Banks, X. Sean Yu, Qian Shi, Jean X. Jiang

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

We previously reported that, among the three connexins expressed in chick lens, overexpression of conneidn (Cx) 45.6, not Cx43 or Cx56, stimulates lens cell differentiation; however, the underlying mechanism responsible for this effect is unclear. Here, we took advantage of naturally occurring loss-of-gap-junction function mutations of Cx50 (ortholog of chick Cx45.6) and generated the corresponding site mutants in Cx45.6: Cx45.6(D47A) and Cx45.6(P88S). In contrast to wild-type Cx45.6, the mutants failed to form functional gap junctions, and Cx45.6(P88S) and, to a lesser degree, Cx45.6(D47A) functioned in a dominant-negative manner. Interestingly, overexpression of both mutants incapable of forming gap junctions significantly increased epithelial-fiber differentiation to a level comparable to that of wild-type Cx45.6. To map the functional domain of Cx45.6, we generated a C-terminus chimera as well as deletion mutants. Overexpression of Cx56*45.6C, the mutant in which the C-terminus of Cx56 was replaced with that of Cx45.6, had a stimulatory effect on lens cell differentiation similar to that of Cx45.6. However, cells overexpressing Cx45.6*56C, the mutant in which C-terminus of Cx45.6 was replaced with that of Cx56, and Cx45.6(-C), in which the C-terminus was deleted, failed to promote differentiation. Taken together, we conclude that the expression of Cx45.6, but not Cx45.6-dependent gap junction channels, is involved in lens epithelial-fiber cell differentiation, and the C-terminal domain of Cx45.6 plays a predominant role in mediating this process.

Original languageEnglish (US)
Pages (from-to)3602-3612
Number of pages11
JournalJournal of cell science
Volume120
Issue number20
DOIs
StatePublished - Oct 15 2007

Keywords

  • Cell communication
  • Connexin 45.6
  • Gap junctions
  • Lens cell differentiation
  • Mutants

ASJC Scopus subject areas

  • Cell Biology

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