INVOLVEMENT OF NOTCH-1 IN MAMMALIAN RETINAL NEUROGENESIS - ASSOCIATION OF NOTCH-1 ACTIVITY WITH BOTH IMMATURE AND TERMINALLY DIFFERENTIATEDCELLS

The Notch pathway is thought to define an evolutionarily conserved sig naling mechanism that regulates the differentiation of immature cells through cell interactions. We have examined the expression of the Notc h-1 receptor, the central element of this pathway, in the developing r at retina, where cell-fate choices depend upon a series of local cell interactions. Notch-1 immunoreactivity is associated with differentiat ing cells at different stages of retinal neurogenesis, suggesting that Notch-1 may play a role in the successive cell-fate determination whi ch governs retinal development. In addition, the Notch-1 immunoreactiv ity is detected in nuclei of postmitotic, differentiated neurons of th e adult retina. Our observations raise the possibility that besides it s role in the differentiation of immature cell populations Notch-1 act ivity may also be involved in the maintenance of the differentiated st ate.