PDGF MEDIATES A NEURON-ASTROCYTE INTERACTION IN THE DEVELOPING RETINA

Astrocytes invade the developing retina from the optic nerve head, ove r the axons of retinal ganglion cells (RGCs). RGCs express the platele t-derived growth factor A-chain (PDGF-A) and retinal astrocytes the PD GF alpha-receptor (PDGFR alpha), suggesting that PDGF mediates a parac rine interaction between these cells. To test this, we inhibited PDGF signaling in the eye with a neutralizing anti-PDGFR alpha antibody or a soluble extracellular fragment of PDGFR alpha. These treatments inhi bited development of the astrocyte network. We also generated transgen ic mice that overexpress PDGF-A in RGCs. This resulted in hyperprolife ration of astrocytes, which in turn induced excessive vasculogenesis. Thus, PDGF appears to be a link in the chain of cell-cell interactions responsible for matching numbers of neurons, astrocytes, and blood ve ssels during retinal development.