Prenatal lens development in connexin43 and connexin50 double knockout mice

Purpose. To determine the roles of intercellular communication in embryonic eye growth and development, mice with a targeted deletion of the Cx43 gene were examined, and mice without both Cx43 and Cx50 were generated and anal yzed. Methods. Embryonic eyes and lenses from wild-ty. pe mice, or mice deficient in Cx43, Cx50, or both Cx43 and Cx50 were collected and analyzed structura lly by light and electron microscopy, immunohistochemically using connexin- specific antibodies. biochemically by Western blot analysis, and physiologi cally by measuring patterns of junctional communication revealed by iontoph oretic injection of junction-permeable reporter molecules. Results. Cx50 expression was limited to the Ocular lens and was not detecte d in either the cornea or the retina. Cx43(-/-) embryos showed development of structurally normal lenses and eyes when examined by light and electron microscopy through embryonic day (E) 18.5. In addition, Cx43(-/-) lense's s ynthesized four different markers of lens differentiation: MIP26, alphaA-cr ystallin, alphaB-crystallin, and gamma -crystallin. Double-knockout lenses were also histologically normal through E18.5 and synthesized the four lens differentiation markers. When assayed by intracellular injection with Luci fer yellow (Molecular Probes. Eugene, OR) and neurobiotin at E15.5, Cx43(-/ -)/Cx50(-/-) lenses retained gap junction-mediated dye transfer between fib er cells. in contrast, dye transfer in double-knockout lenses was dramatica lly reduced between epithelial cells and was eliminated between epithelial cells and fibers. Conclusions. These data indicate that the unique functional properties of b oth Cx43 and Cx50 are not required for prenatal lens development and that c onnexin diversity is required for regulation of postnatal growth and homeos tasis.