Gap junctions, consisting of
connexins, allow the exchange of small molecules (less than 1 KD) between adjacent cells, thus providing a mechanism for synchronizing the responses of groups of cells to environmental stimuli.
Connexin 31 is a member of the
connexin family. Mutations on
connexin 31 are associated with
erythrokeratodermia variabilis,
hearing impairment and
peripheral neuropathy. However, the pathological mechanism for
connexin 31 mutants in these diseases are still unknown. In this study, we analyzed the assembly, trafficking and metabolism of
connexin 31 in HeLa cells stably expressing
connexin 31.
Calcein transfer assay showed that
calcein transfer was inhibited when cells were treated with
Brefeldin A or
cytochalasin D, but not when treated with
nocodazole or a-
glycyrrhetinic acid, suggesting that Golgi apparatus and actin filaments, but not microtubules, are crucial to the trafficking and assembly of
connexin 31, as well as the formation of gap junction intercellular communication by
connexin 31. Additionally, a-
glycyrrhetinic acid did not effectively inhibit gap junctional intercellular communication formed by
connexin 31. Pulse-chase assay revealed that
connexin 31 had a half-life of about 6 h. Moreover, Western blotting and fluorescent staining demonstrated that in HeLa cells stably expressing
connexin 31, the amount of
connexin 31 was significantly increased after these cells were treated with proteasomal or lysosomal inhibitors. These findings indicate that
connexin 31 was rapidly renewed, and possibly degraded by both proteasomal and lysosomal pathways.