Genetic diseases and gene knockouts reveal diverse connexin functions

Intercellular channels present in gap junctions allow cells to share small molecules and thus coordinate a wide range of behaviors. Remarkably, althou gh junctions provide similar functions in all multicellular organisms, vert ebrates and invertebrates use unrelated gene families to encode these chann els. The recent identification of the invertebrate innexin family opens up powerful genetic systems to studies of intercellular communication. At the same time, new information on the physiological roles of vertebrate connexi ns has emerged from genetic studies. Mutations in connexin genes underlie a variety of human diseases, including deafness, demyelinating neuropathies, and lens cataracts. In addition, gene targeting of connexins in mice has p rovided new insights into connexin function and the significance of connexi n diversity.