Neurotrophin signaling and Alzheimer's Disease neurodegeneration - Focus on BDNF/TrkB signaling

Neurotrophins are small proteins vital for neuronal growth, differentiation, survival, and plasticity. Members of the mammalian neurotrophin family include nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin- 4/5 (NT-4/5). Their neurotrophic effects are mediated by the tropomyosin receptor kinase (Trk) receptors, membrane-bound receptor tyrosine kinases (NGF for TrkA, BDNF and NT4/5 for TrkB, and NT-3 for TrkC) which activate various cell signaling pathways linked to growth, differentiation, and survival. The importance of neurotrophin signaling in brain development is highlighted by findings showing that knockout mice for any one of the neurotrophins or their receptors are fatal or exhibit severe neural defects.