Cultured chicken embryo lens cells resemble differentiating fiber cells invivo and contain two kinetic pools of connexin56

The lens is an avascular organ in which gap junctions play a pivotal role f or cell physiology and transparency. Here we evaluate a lens culture system as a model for studies of lens gap junction dynamics. In culture, chicken embryo lens cells initially form a monolayer of epithelial cells. Subsequen tly, the epithelial cells differentiate into lentoids, birefringent multice llular structures composed of fiber-like cells. We examined the cultures fo r the expression of cellular markers and lens fiber specific proteins using immunofluorescence and immunoblot analysis. We also determined the half-li fe of connexin56 (Cx56), a fiber-specific gap junction protein. All lens ce lls in culture expressed actin, endoplasmic reticulum proteins and N-cadher in. Only lentoid cells expressed the lens fiber connexins, Cx45.6 and Cx56. Cx56 localized at appositional membranes and did not co-localize with endo plasmic reticulum proteins or N-cadherin. Two pools Of Cx56 were detected i n these cultures, one with a half-life of a few hours and the other with a half-life of days. The two pools contained phosphorylated forms of Cx56 of different apparent molecular weights. These results suggest that lens cells in culture can be used as a model for the study of lens biology. They also suggest that phosphorylation of Cx56 might be regulating the stability of the protein. (C) 1999 Academic Press.