The Arf Tumor Suppressor Regulates Platelet-Derived Growth Factor Receptor ? Signaling: A New View through the Eyes of Arf-/- Mice

Arf is a key mammalian tumor suppressor gene known to be activated in response to aberrant mitogenic signals leading to both p53-dependent and -independent effects. We recently uncovered a new and somewhat unexpected function for mouse Arf as a regulator of mural cell accumulation within an ocular vascular bed destined to regress in the postnatal period. We found that the Arf gene product, p19Arf, blocks mural cell proliferation driven by Platelet-derived growth factor receptor ? (Pdgfr?) in the developing vitreous. In vivo studies and analyses of cultured cells indicate that p19Arf dampens the expression of Pdgfr?. In cultured mouse embryo fibroblasts, p19Arf accomplishes this independently of two established effectors - Mdm2 and p53. Our findings indicating that p19Arf responds to specific developmental cues to disrupt Pdgfr? signaling in the developing eye extend existing paradigms for Arf tumor suppressor gene biology.