Tryptamine-induced tryptophanyl-tRNAtrp deficiency in neurodifferentiation and neurodegeneration interplay: progenitor activation with neurite growth terminated in Alzheimer's disease neuronal vesicularization and fragmentation

J Alzheimers Dis. 2011;26(2):263-98. doi: 10.3233/JAD-2011-110176.


Tryptophanyl-tRNA synthetase (TrpRS) catalyzes tryptophanyl-tRNAtrp formation. At concentrations exceeding tryptophan, tryptamine inhibits TrpRS. This leads in tryptophanyl-tRNA deficiency and synthesis of aberrant proteins. Tryptamine presents in food and crosses blood-brain barrier. The purpose of this study is to test the hypothesis that tryptamine-induced changes in cell and animal models correlate with Alzheimer's disease (AD) manifestations. Tryptamine prevented growth of human neuroblastoma. Epithelioids recovered growth in tryptamine-free medium, while neuroblasts died. Tryptamine induced epithelioid differentiation forming synaptic vesicles, neuritic contacts, and TrpRS+ axons in stable sublines. A fraction of epithelioids was adhered to satellite cells via trypsin-resistant interdigitating junctions. Tryptamine stimulated satellite division and differentiation into neurons, transitional cell variants and neuroblasts able to repopulate. Both tryptamine-inhibited and hypoxia-downregulated TrpRS translocates into cytoplasmic extensions. TrpRS is secreted into extracellular space as a free protein or within vesicles extended from cytoplasm and then pinched-off from plasma membrane of tryptamine-treated cells. Extracellular vesicles fuse in congophilic TrpRS+ plaques in tryptamine-treated culture and AD brain. TrpRS prominent immunoreactivity is associated with plasma and vesicle membranes of satellites and AD brain degenerated neurons. Tryptamine-modified mouse brain expresses amyloid and abnormal filaments in extracellular and neuronal plasma membrane vesicles. Radiolabeled tryptamine, tryptophan and serotonin uptake was 10-fold lower in tryptamine-resistant compared to tryptamine-sensitive cells. In both variants, tryptamine uptake exceeded tryptophan uptake within 2-h assuring TrpRS inhibition. Here, tryptophanyl-tRNAtrp deficiency implicates in both neurite growth and termination/collapse. Neurite growth termination prompts TrpRS+ vesicularization. TrpRS+ vesicles contribute in neuronal fragmentation and fibrillar-vesicular congophilic plaques in AD brain.

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Humans
  • Mice
  • Nerve Degeneration / metabolism*
  • Neurites / drug effects
  • Neurites / metabolism*
  • Neurogenesis / drug effects
  • Neurogenesis / physiology*
  • Neurons / metabolism
  • Tryptamines / pharmacology*
  • Tryptophan-tRNA Ligase / antagonists & inhibitors
  • Tryptophan-tRNA Ligase / metabolism*


  • Tryptamines
  • tryptamine
  • Tryptophan-tRNA Ligase