Wrong connexin signals cataracts

Besides allowing ions to flow between adjacent cells, gap junctions selectively conduct larger signaling molecules. What determines their selectivity is unknown. Martinez-Wittinghan et al. (page 969) explored this problem by extensively manipulating the genetic loci of the two connexin proteins that make up gap junctions in the lens of the eye. The results show that the developing lens is exquisitely sensitive to changes in the composition of gap junctions, and that alterations in gap junction permeability could underlie human diseases ranging from cataracts to deafness.

In previous studies, mice lacking the connexin 46 gene, which is expressed primarily in fiber cells beneath the lens epithelium, grew lenses of normal size but with severe cataracts. Deletion of the connexin 50 gene, which is expressed in both the lens epithelium and...