Valerie Wallace, PhD

(613) 737-8234 (T)
(613) 737-8803 (F)
vwallace@ohri.ca

Mammalian retinal development

A major interest in my laboratory lies in the identification of the cell-cell interactions that regulate cell diversification during brain development, using the mammalian retina as a model system. All of the cell types in mature retina, with the exception of astrocytes, are derived from multipotential precursor cells. Although there is evidence that cell-cell interactions play a role in regulating retinal development, the nature of the cell-cell interaction requirement is poorly understood. We have recently shown that retinal ganglion cells, the earliest neurons generated in the retina, communicate with retinal precursor cells via Sonic hedgehog, an intercellular signaling molecule. Experiments in my laboratory are aimed at understanding the functional significance of this cell-cell interaction in the developing and adult retina.

Optic nerve development

The optic nerve is a simple system for studying neuron-glia communication in the developing central nervous system since it contains only the axons of the retinal ganglion cells and two glial cell types, astrocytes and oligodendrocytes. Axon-derived signals have been shown to promote the proliferation of astrocytes in the nerve, but the identity of many of these signals is unknown. We have recently provided evidence that Sonic hedgehog is associated with the axons of retinal ganglion cells and that it promotes the proliferation of astrocyte lineage cells in the developing optic nerve. Ongoing experiments in my laboratory involve the use cell culture systems and transgenic mouse models to explore the role of axon derived signals in gliogenesis in the optic nerve.