Inside every cell in your brain, tiny droplets made of proteins, RNA, and DNA are hard at work keeping your neurons functioning. But in diseases like Alzheimer's, these normally helpful droplets can harden into toxic clumps called fibrils, disrupting the cellular machinery that keeps our minds sharp. Now, researchers at the University at Buffalo have discovered that a simple molecule already present in our bodies might be able to stop that from happening.
The team, led by biophysicist Priya R. Banerjee, Ph.D., found that L-arginine—an amino acid our cells naturally produce—can protect these protein droplets from converting into the harmful fibrils associated with Alzheimer's disease. Their findings, published in the journal Nature Communications, represent a potential breakthrough in understanding how to prevent neurodegeneration without disrupting the healthy processes our cells depend on.
"Healthy cells might already be using small molecules like L-arginine to stabilize functional droplets and prevent them from conversion to toxic assemblies," Banerjee said. The discovery suggests our own biology may hold clues to fighting the very diseases that threaten it.
The research focused on a protein called Tau, which forms droplets that can gradually convert into fibrils known as amyloids. Unlike the well-known amyloid-β plaques that accumulate outside neurons, Tau fibrils build up inside them—making them harder to target with traditional treatments. Using an engineered version of Tau, the team created a model system that let them watch exactly how droplets transition from liquid-like and functional to solid-like and harmful.
What they found surprised them: the dangerous conversion happens at the surface of the droplets, not in their interiors. "The inside of the droplet is liquid-like and functional, but the droplet interface poses a risk and likely promotes fibril formation," explained Tharun Selvam Mahendran, a Ph.D. student in Banerjee's lab and the study's first author. This means it may be possible to keep droplets intact while blocking fibril formation at the surface—preserving their normal function while preventing their breakdown.
After screening several naturally occurring molecules, the researchers discovered that L-arginine does exactly that. The amino acid enhances droplet stability, protecting against amyloid formation and preserving the droplets' ability to assemble and stabilize microtubules—the cellular highways that transport materials within neurons.
Banerjee emphasizes this work serves as proof of principle that two seemingly connected processes—normal protein droplet formation and disease-linked fibril formation—can be separated. "The proof-of-principle approach that we demonstrated could help guide efforts to develop small molecules that target fibril formation in Alzheimer's disease," he said.
While much more research lies ahead, the findings offer a hopeful new avenue: rather than broadly attacking protein clumps, future treatments might fine-tune the molecular environment inside neurons to prevent those clumps from forming in the first place. For the 50 million people worldwide living with dementia, that possibility is anything but trivial.