INDUCTION OF APOPTOSIS BY THE LOW-AFFINITY NGF RECEPTOR

Nerve growth factor (NGF) binding to cellular receptors is required fo r the survival of some neural cells. In contrast to Trk A, the high-af finity NGF receptor that transduces NGF signals for survival and diffe rentiation, the function of the low-affinity NGF receptor, p75NGFR, re mains uncertain. Expression of p75NGFR induced neural cell death const itutively when p75NGFR was unbound; binding by NGF or monoclonal antib ody, however, inhibited cell death induced by p75NGFR. Thus, expressio n of p75NGFR may explain the dependence of some neural cells on NGF fo r survival. These findings also suggest that p75NGFR has some function al similarities to other members of a superfamily of receptors that in clude tumor necrosis factor receptors, Fas (Apo-1), and CD40.