Connexins in lens development and disease

Gap junctions are responsible for the coupling of cells that enables intercellular exchange of ions, small metabolites, and nutrients; lens homeostasis depends on these intercellular connections. Aberrant expression of the genes encoding lens connexins (Cx43, Cx46, and Cx50), and function of the connexins themselves, have been linked to cataractogenesis and ocular growth defects. The use of in vivo and in vitro experimental models has provided significant advances in understanding the function of gap junctions in the lens. Current data suggest that Cx46 is required for maintenance of lens clarity via its effects on Ca²⁺ homeostasis, and that Cx50 is required for proper lens growth. The substitution of either of these connexins for the other only partially ameliorates the pathological effects. In spite of these advances, questions about the mechanisms by which connexin-related pathologies occur in the mammalian lens remain largely unanswered.