Recombinant Human NT-4 (carrier-free)

Neurotrophins are growth factors that modulate growth, differentiation, and survival of neurons. Structure related proteins include neuron growth factor (NGF), brain derived neurogenic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4). They are highly homologous and share a similar structure with a tertiary folded, cysteine rich "knot". Neurotrophins are critical to the development of the central and peripheral nervous systems and play important roles in injury induced neuron regeneration. NT-4 is encoded by the NTF4 gene. The name NT-4/5 arose from the uncertainties between neurotrophin-5 found in humans and neurotrophin-4 identified in Xenopus. Although NT-4 is structurally the most divergent neurotrophin, like BNDF NT-4 binds to receptor TrkB with high affinity and mediates similar functions with BDNF in neurogenesis. However, similar to NGF and NT-3 gene-knockouts, the disruption of BDNF function severely affects neuron development. However, NT-4 knockout mice show minor deficits, with nearly 50% neuron loss in nodose-petrosal and geniculate ganglia. The double knockouts of BDNF and NT-4 present additive deficit phenotype compared to NT-4 knockout mice. It is thus suggested that there are two groups of downstream target cells through multiple coreceptors interaction of BDNF/TrkB and NT-4/TrkB signaling. There are also some exceptions of biological actions of NT-4 that are not parallel with BDNF function. NT-4, but not BDNF, is reported to promote survival of striatal neurons and is able to overturn spatial memory impairments in aged rats. NT-4 is also suggested to participate in stem cell differentiation toward oligodendrocyte progenitor cells in the brain.