Review The proteasome: A key modulator of nervous system function, brain aging, and neurodegenerative disease, 2023, Davidson et al

hotblack

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The proteasome: A key modulator of nervous system function, brain aging, and neurodegenerative disease

Davidson, K., & Pickering, A. M.

Abstract
The proteasome is a large multi-subunit protease responsible for the degradation and removal of oxidized, misfolded, and polyubiquitinated proteins. The proteasome plays critical roles in nervous system processes. This includes maintenance of cellular homeostasis in neurons. It also includes roles in long-term potentiation via modulation of CREB signaling.

The proteasome also possesses roles in promoting dendritic spine growth driven by proteasome localization to the dendritic spines in an NMDA/CaMKIIα dependent manner. Proteasome inhibition experiments in varied organisms has been shown to impact memory, consolidation, recollection and extinction. The proteasome has been further shown to impact circadian rhythm through modulation of a range of ‘clock’ genes, and glial function.

Proteasome function is impaired as a consequence both of aging and neurodegenerative diseases. Many studies have demonstrated an impairment in 26S proteasome function in the brain and other tissues as a consequence of age, driven by a disassembly of 26S proteasome in favor of 20S proteasome. Some studies also show proteasome augmentation to correct age-related deficits.

In amyotrophic lateral sclerosis Alzheimer’s, Parkinson’s and Huntington’s disease proteasome function is impaired through distinct mechanisms with impacts on disease susceptibility and progression. Age and neurodegenerative-related deficits in the function of the constitutive proteasome are often also accompanied by an increase in an alternative form of proteasome called the immunoproteasome.

This article discusses the critical role of the proteasome in the nervous system. We then describe how proteasome dysfunction contributes to brain aging and neurodegenerative disease.

Link (Frontiers in cell and developmental biology)
https://doi.org/10.3389/fcell.2023.1124907
 
Not evidence but more of my hand waiving learning and thinking. But thought others may be interested. I came across things while thinking about and reading up on areas around the proteasome, ubiquitin and general maintenance and cleanup, with a mind on synapses and mtDNA.

A bit focused on degeneration but the regulation aspects and links to immune system and CLOCK seem potentially relevant.
 
Another related paper


As above I’ve been thinking about mechanisms which may tie together things others have been talking about, some data we have, etc. My current pondering is what if there is something wrong around the proteasome, so that things aren’t properly cleaned up in two places.

In the muscle after physical activity, so mtDNA isn’t properly removed and we get the interferon triggering talked about elsewhere. Here the proteasome degrades proteins on the outer surface of damaged mitochondria which is part of the process of breaking them down, so if it’s not working as well as it should..

And at the synapse, here the proteasome degrades regulatory proteins that control the release and re-packaging of neurotransmitters. So if that’s not working as well as it should we get problems downstream with neurotransmitters and synapses. Things not firing or not silenced.

That’s the vague idea anyway
 
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On CLOCK and circadian rhythms
The periodic expression of many clock proteins is heavily reliant on the proteasome system. Thus, impaired proteasome function results in altered or impaired circadian rhythm.
The cyclical nature of many proteins involved in circadian rhythm is produced in part by cyclical protein degradation. Proteins are polyubiquitinated in a rhythmic fashion to facilitate rhythmic oscillation in their expression.

I’ve found another review which covers this topic in more detail and will post later.
 
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