Endoplasmic Reticulum Stress as a Mediator of Neurotoxin-Induced Dopamine Neuron Death
Abstract
Programmed cell death (PCD) is an important mediator of neural degeneration in Parkinson's disease (PD). The goal of this proposal was to examine in vivo the possible role of ER stress, a mediator of PCD, in dopamine neuron death. This was done by studying mice with targeted deletions of CHOP, an upstream transcriptional mediator, and caspase-12, a downstream mediator, of ER stress-induced apoptosis. We have found that CHOP is universally expressed in neurotoxin models of PD, and that it is an essential mediator of apoptosis in the 6OHDA neurotoxin model. The CHOP null mutation does not, however, protect dopamine neurons in the chronic MPTP model, indicating that these two models are mediated by distinct mechanisms. Although CHOP is best known as a death mediator due to ER stress, we were unable to confirm the presence of ER stress in the 6OHDA model by analysis of BiP and the XBP-1 splice variant. Furthermore, we have shown that caspase-12 null mice are not protected from 6OHDA. Since caspase-12 is a critical mediator of PCD due to ER stress, these results suggest that the upregulation of CHOP in the 6OHDA model is not mediated by ER stress, but rather oxidative insult. In the final year of this award, we have found that homozygous JNK2/3 double null mutations diminish the induction of CHOP, indicating that the MAPK pathway regulates its expression. We have found also that JNK2 and JNK3 are essential mediators of neuron death in this neurotoxin model.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2007
- Accession Number
- ADA476089
Entities
People
- Robert E Burke
Organizations
- Columbia University