The role of Wnt/β‐catenin signaling pathway in lens and retina development

Wnt/β‐catenin signaling pathway functions by regulating the amount of the transcriptional co‐activator β‐catenin that controls key developmental gene expression programs. However, β‐catenin is known to have a dual function in cells. Apart from its key role as a nuclear effector of Wnt/β‐catenin signaling pathway (transcriptional function), β‐catenin is an integral structural component of cadherin‐based adherens junctions (cytoskeletal function). The essential role of β‐catenin during development is demonstrated by the finding that β‐catenin knockout mice fail to develop beyond embryonic day E6.5. Tissue‐specific deletion of β‐catenin gene in lens and neural retina resulted in a number of ocular phenotypes such as formation of ectopic lenses, failure to form lens vesicle, altered fiber cell differentiation and disruption of typical laminated structure of neural retina. In order to distinguish the phenotypes resulting from cytoskeletal or transcriptional function of β‐catenin we used mouse strain, in which the endogenous β‐catenin is replaced by mutant form of the protein, retaining cytoskeletal but lacking transcriptional function. We found that mice deficient for transcriptionally competent β‐catenin manifest abnormal development of lens epithelium and ciliary marginal zone of the neural retina. Our data unequivocally identify specific roles of canonical Wnt signaling for lens and neural retina development.