A single protein may hold the key to preventing brain cell death in neurodegenerative diseases like Parkinson’s and Alzheimer’s, according to new research from Rockefeller University that challenges decades of conventional thinking about what causes these devastating conditions.
The study, published in the Proceedings of the National Academy of Sciences, demonstrates that boosting levels of a protein called PI31 can prevent neuronal degeneration and extend lifespan up to fourfold in laboratory models of rare genetic disorders similar to Parkinson’s disease.
“A number of diseases—Alzheimer’s, Parkinson’s—are in fact diseases of synaptic dysfunction, at least initially. Now that we’ve shown how to eliminate unwanted proteins at the synapse, we hope this will lead to a revolution in treating common age-related disorders.”
The findings represent a fundamental shift away from targeting the protein clumps that riddle diseased brains toward fixing the cellular machinery that cleans up protein waste before it can accumulate into toxic aggregates.
The Transport Problem
Hermann Steller, head of the Strang Laboratory of Apoptosis and Cancer Biology at Rockefeller, has long suspected that protein plaques are a symptom rather than a cause of neurodegeneration. His team’s research focuses on proteasomes, the cell’s protein-degrading machines that must travel long distances from the cell body to nerve endings to clear out damaged proteins at synapses.
PI31 acts as an adaptor that loads proteasomes onto cellular motors for this critical journey to synapses, where neurons communicate. Without PI31, transport stalls, protein waste accumulates, and eventually aggregates form. The researchers found that flies and mice lacking PI31 develop signs of neurodegeneration, while mutations affecting PI31 function have been implicated in multiple neurodegenerative diseases.
The protein’s importance became clear when Steller’s team discovered that variants of the PI31 gene appear in patients with Alzheimer’s, ALS, and Parkinson’s disease. This prompted them to test whether artificially boosting PI31 levels could ward off neurodegeneration entirely.
Striking Results Across Species
Testing their hypothesis in fruit fly models first, the researchers inactivated FBXO7, a gene that when mutated causes early-onset Parkinson’s-like symptoms in humans. As expected, flies developed severe motor defects and disrupted proteasome transport. But when the team added extra copies of PI31, these symptoms largely reversed as proteasomes began moving normally again.
The mouse experiments proved even more dramatic. Even modest increases in PI31 levels strongly suppressed neuronal degeneration, preserved motor function, and improved overall health in FBXO7-deficient mice. In some cases, lifespan extended nearly fourfold from 22 days to 89 days.
“The degree to which we can rescue the various defects in mice is remarkable.”
PI31 also cleared away abnormal tau proteins, a hallmark of Alzheimer’s disease, suggesting the approach could work across multiple neurodegenerative conditions.
The research revealed surprising dose sensitivity. Mice with one copy of the PI31 transgene lived twice as long as untreated animals, while those with two copies lived four times longer. Remarkably, even modest levels of PI31 overexpression were well tolerated with no obvious side effects throughout the animals’ lifespans.
What makes these results particularly compelling is their clinical relevance. The FBXO7 mutations studied cause Parkinsonian Pyramidal Syndrome in humans, and recent work has identified patients with rare PI31 mutations who suffer from similar neurodegenerative conditions.
The team’s working model suggests that when PI31 activity diminishes, fewer active proteasomes reach synapses, increasing the likelihood that proteins tagged for destruction escape degradation and form aggregates. These aggregates can then inhibit remaining proteasomes, creating a destructive cycle of increasing protein toxicity.
Steller believes this approach could eventually slow age-related cognitive decline and tackle common diseases like Alzheimer’s. The research team is now testing whether PI31 can preserve cognitive function in aging mice, with hopes of moving toward preclinical development for human therapies.
One promising avenue could be gene therapy using adeno-associated viruses to deliver PI31, an approach that has proven clinically successful for other neurological disorders. Patients with PI31 or FBXO7 deficiency would be obvious early candidates, potentially paving the way for broader applications in more common neurodegenerative diseases.
The implications extend beyond any single condition. By targeting the fundamental mechanisms that maintain protein balance at synapses, this approach addresses what may be a common pathway underlying multiple age-related brain diseases.
Proceedings of the National Academy of Sciences: 10.1073/pnas.2511899122
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