- Amyotrophic lateral sclerosis (ALS) is characterized by the degeneration of motor neurons in the motor cortex and spinal cord. Recent evidence suggests that the purine receptor P2X7 (P2X7R) plays a central role in the pathology of ALS. Previous research indicates that P2X7R activation by oxidatively modified heat shock protein 90 (Hsp90) or Hsp90 inhibition stimulates motor neuron death. The composition of the P2X7 receptor complex, which includes Hsp90, is cell and species specific and is unknown in motor neurons.
The purpose of this study was to investigate whether post-translational compositional differences in the P2X7R complex between healthy and ALS patients exist. We hypothesized that immunoprecipitation and mass spectrometry would indicate that the P2X7R complex is particularly vulnerable to ligand-independent activation by Hsp90 nitration in ALS patients. Before immunoprecipitation and mass spectrometry could be performed, lentivectors carrying green fluorescent protein under the regulation of the motor neuron promoter Hb9 were produced and were added to motor neurons derived from the inducible neuroprogenitor cells of ALS and healthy patients.
Fluorescence in the motor neurons was observed but documented poorly and will have to be repeated. Additionally, the motor neurons died before immunoprecipitation could be performed and subsequent differentiations failed. Future research will compare mass spectrometry results of the P2X7R complex of healthy and ALS patients. If differences are found, subsequent studies should focus on constructing ligands that occupy ALS-specific P2X7R complex regions and testing their efficacy/safety against the control: healthy patients' P2X7R complex.
Key Words: P2X7 receptor, ALS, motor neurons, Hsp90