LENS GAP JUNCTIONS--IDENTITY AND PROPERTIES

In the lens, gap junctions and the abundant membrane proteins MP26 and MP20 are believed to play major roles in maintaining ocular transparency; cataractous changes occur in mice lacking gap junction protein expression and with mutations in MP26 or MP20. The overall goals of this grant application are to determine more precisely the properties and functional roles of lens gap junctions and of lens MP proteins in order to more fully understand how altered expression or function of these proteins results in eye pathology. Preparations to be studied include mammalian cell lines in which lens gap junction proteins (Cx43, Cx46 and Cx50) and MP proteins (MP26 and MP20) are individually expressed and cultures of lens epithelial cells from wildtype mice and littermates lacking gap junction or MP expression. Techniques to be applied include confocal immunocytochemistry to determine the distribution patterns of these proteins, whole cell voltage clamp with patch electrodes to determine properties of the membrane channels, and optical imaging to evaluate Ca2+ wave propagation in cultures and volume regulation in the cells. Through the use of this combination of techniques on these preparations, we believe that we will gain new insight into both normal physiological functions of these abundant proteins in the lens and also determine how abnormalities in these proteins leads to lens dysfunction.