Development and Use of Small-Molecule Activators of Neuroproteasomes to Treat ALS
Abstract
To stay healthy and long-lived, all cells must maintain an intricate balance between protein synthesis, maintenance, and degradation. Dysfunctions in these mechanisms of protein homeostasis can lead to protein aggregation and cell death. Protein aggregation and death induced by proteostasis dysfunction is a common theme among almost all neurodegenerative diseases, including Amyotrophic Lateral Sclerosis (ALS). The dogma of selective protein degradation is that intracellular proteasomes degrade ubiquitin-tagged proteins tagged and destined for degradation. However, our laboratory has discovered a new node of protein homeostasis - a novel proteasome that is specific to neurons and does not require ubiquitylation of substrates. Our extensive previous findings reveal that these neuroproteasomes are embedded in neuronal plasma membranes and exposed to the extracellular space. Neuronal-specific plasma membrane-bound proteasomes (NMPs) represent an entirely new strategy for degrading proteins in the brain. Previous studies had alluded to a curious and important role for ubiquitin-independent proteasomes in mouse models of ALS as well as in patient samples. However, because the discovery of neuroproteasomes was so recent, it was not clear which species of proteasomes were dysregulated in ALS - the NMP neuroproteasomes or the canonical cytosolic proteasomes. Much to our surprise, when we studies two mouse models of ALS, as well as cellular models of ALS, we found that the neuroproteasomes were the only species of proteasome which were strongly dysregulated. Using NMP-specific inhibitors which we previously described and validated, we find that inhibition of NMP function causes protein aggregation consistent with ALS pathology. We also found that genetic risk factors for ALS act to inhibit neuroproteasome activity.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2022
- Accession Number
- AD1199733
Entities
People
- Kapil Ramachandran
Organizations
- Columbia University