Pelizaeus-Merzbacher-like disease is caused not only by a loss of connexin47 function but also by a hemichannel dysfunction

Eur J Hum Genet. 2010 Sep;18(9):985-92. doi: 10.1038/ejhg.2010.61. Epub 2010 May 5.


Autosomal recessive mutations in the GJA12/GJC2 gene encoding the gap junction protein connexin47 (C x 47) cause a form of Pelizaeus-Merzbacher-like disease (PMLD) with hypomyelination, nystagmus, impaired psychomotor development and progressive spasticity. We investigated the functional consequences of four C x 47 missense mutations (G149S, G236R, T265A, and T398I) and one C x 47 complex mutation (A98G_V99insT) by immunoblot analysis and immunocytochemistry in transfected communication-incompetent HeLa cells and in OLI-neu cells. All studied C x 47 mutants, except G236R, generated stable proteins in transfected HeLa cells and OLI-neu cells. The mutants T265A and A98G_V99insT were retained in the ER, T398I formed gap junctional plaques at the plasma membrane, and G149S showed both, structures at the plasma membrane and ER localization. Two-microelectrode voltage clamp analyses in Xenopus laevis oocytes injected with wild-type and mutant C x 47 cRNA revealed reduced hemichannel currents for G236R, T265A, and A98G_V99insT. In contrast, T398I revealed hemichannel currents comparable to wild-type. For C x 47 mutant T398I, our results indicate a defect in hemichannel function, whereas C x 47 mutants G149S, G236R, T265A, and A98G_V99insT are predicted to result in a loss of C x 47 hemichannel function. Thus, PMLD is likely to be caused by two different disease mechanisms: a loss of function and a dysfunction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Connexins / genetics*
  • Connexins / physiology
  • Electrodes
  • HeLa Cells
  • Humans
  • Immunohistochemistry
  • Ion Channels / chemistry
  • Ion Channels / genetics
  • Ion Channels / physiology*
  • Molecular Sequence Data
  • Mutation, Missense
  • Pelizaeus-Merzbacher Disease / genetics*
  • Xenopus laevis


  • Connexins
  • Ion Channels
  • connexin 47