THE EXPRESSION AND FUNCTION OF NOTCH PATHWAY GENES IN THE DEVELOPING RAT EYE

The Notch gene plays a role in the development of disparate tissues in multiple organisms. Because the vertebrate eye is an excellent model system for both patterning and cell fate determination, two processes that can involve Notch, we examined the expression patterns of Notch 1 and Notch 2, and their ligands Delta and Jagged, in the developing ra t eye. Notch 1 and Delta were found to be expressed in the neural reti na during the period of cell fate determination and differentiation. N otch 2 was found to be expressed in the non-neuronal derivatives of th e optic cup, including the pigment epithelium, optic stalk, and ciliar y body. Jagged was expressed in distinct regions within the optic vesi cle, ciliary body, and lens, with patterns that changed over time. The potential function of Notch 2 in cell-type specification and differen tiation was examined by introducing a constitutively active form of No tch 1 in vivo using a replication-incompetent retrovirus. This form of Notch 1 was found to cause abnormal growth and interfere with the dif ferentiation of multiple retinal cell types.