Nerve growth factor induces cell cycle arrest of astrocytes

Neurotrophins can influence multiple cellular functions depending on the cellular context and the specific receptors they interact with. These neurotrophic factors have been extensively studied for their ability to support neuronal survival via Trk receptors and to induce apoptosis via the p75NTR. However, the p75NTR is also detected on cell populations that do not undergo apoptosis in response to neurotrophins. In particular, the authors have detected p75NTR expression on astrocytes during development and after seizure-induced injury. In this study, the authors investigated the role of Nerve growth factor (NGF) in regulating astrocyte proliferation and in influencing specific aspects of the cell cycle. The authors have demonstrated that NGF prevents the induction of cyclins and their association with specific cyclin-dependent kinases, and thereby prevents progression through the G1 phase of the cell cycle. Since the authors have previously shown that p75NTR but not TrkA, is expressed in astrocytes, these data suggest that activation of p75NTR promotes withdrawal of astrocytes from the cell cycle, which may have important consequences during development and after injury. (C) 2011 Wiley Periodicals, Inc. Develop Neurobiol 72: 766776, 2012