Differential expression of N- and B-cadherin during lens development

PURPOSE. To analyze the dynamics of N- and B-cadherin cell adhesion molecul e expression and cytoskeletal interaction during embryonic chick lens devel opment. METHODS. Localization of N- and B-cadherin, F-actin, and connexin 56 were d etermined by immunohistochemistry of developing lenses or immunocytochemist ry of differentiating primary lens cultures. Biochemical analysis of cytosk eletal linkage of N- or B-cadherin was assessed by differential detergent e xtraction, electrophoresis, and immunoblotting. RESULTS. The results indicate that although both cadherins are expressed th roughout lens development, N-cadherin expression detected was similar in bo th lens epithelial and fiber cells, whereas B-cadherin was preferentially l ocalized to the lens fiber cells. During differentiation, both cadherins be come increasingly associated with the lens cytoskeleton, as indicated bioch emically by a transition from largely Triton X-100-soluble to Triton X-100- insoluble pools and immunocytologically by cadherin localization to cell-ce ll borders and colocalization with the actin cytoskeleton. Although a signi ficant fraction of N-cadherin remains Triton X-100-soluble as the lens cell s differentiate, B-cadherin becomes resistant to extraction by both Triton X-100 as well as RIPA buffers. As detected immunocytochemically in lens cel l cultures, the temporal localization of N-cadherin to cell-cell interfaces precedes that of B-cadherin. Furthermore, temporal localization of B-cadhe rin, as opposed to N-cadherin, to cell-cell borders more closely parallels that of connexin 56 in vitro as well as in vivo. CONCLUSIONS. These results suggest that while both N- and B-cadherin are ex pressed during lens cell differentiation, both their patterns of expression as well as their cytoskeletal association differ between epithelial and fi ber cells.