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Neuronal Protein Tracing Reveals How the Brain Routes Its Waste

Published

2 weeks ago

May 29, 2026

The brain is one of the busiest organs in the body, constantly processing and reshaping itself. That activity produces an equally constant stream of molecular byproducts—proteins that need to be moved out before they accumulate. When those clearance routes slow or break down, waste lingers, and the consequences can be profound. In Alzheimer’s disease, for example, toxic proteins build up in vulnerable regions. Yet despite decades of research, scientists have lacked a clear view of how waste normally leaves the brain.

A new study from the Gladstone Institutes offers the clearest picture yet of how the brain normally takes out its trash—and what happens when those routes fail. Published in Cell as “Physiological brain clearance architecture revealed by neuronal protein tracing,” the work introduces a method that traces waste proteins from the moment they are produced inside neurons to the moment they leave the brain.

For decades, researchers have relied on injecting tracers into the cerebrospinal fluid (CSF) to visualize drainage. But this approach, while illuminating, shows all possible routes, instead of pinpointing the most-used exit. “These injected tracers disturb the very system we’re attempting to measure,” said lead author Andrew Yang, PhD, a Gladstone investigator. “We wanted to find a better way.”

Yang’s team engineered neurons in mice to produce a fluorescent protein, ZsGreen, that could be followed as it exited the brain through its natural routes. This allowed the researchers to track waste as it moved into the dura, skull, nasal cavity, and lymph nodes—regions populated by specialized immune cells that interact with brain‑derived proteins.

The resulting map diverged sharply from the field’s long‑held assumptions. Traditional CSF tracers had pointed to the cervical lymph nodes as a major drainage site. But the new method revealed that very little neuronal waste actually reaches those nodes. “We were surprised to find that very little ZsGreen drained to the cervical lymph nodes,” Yang said. “Instead, waste drained through the dura, skull, and nasal cavity. Our findings underscore why tracking waste proteins themselves, rather than movement of the cerebrospinal fluid, provides a more accurate understanding of waste clearance dynamics.”

The team also uncovered a striking organizational principle: where a protein is made determines where it drains. Proteins produced in upper forebrain regions exited through upper routes, while those from deeper structures, such as the striatum, used lower pathways. The researchers call this the brain’s “nearest‑exit” model. “It’s like each brain region has a biological ZIP code system to ensure waste will be sent to the correct drainage site,” said Nalini Rao, PhD, a postdoctoral fellow. She noted that in aging or disease, these ZIP codes may become scrambled, potentially explaining why certain regions are more vulnerable to disorders like Alzheimer’s.

Disease models reinforced the system’s fragility. In mice with acute inflammation, ZsGreen leaked directly into the bloodstream, bypassing normal routes. In an Alzheimer’s model, waste became trapped inside the brain, unable to drain effectively. “Understanding how diseases disrupt brain clearance could help us design therapeutics to target the brain border compartments and enhance waste removal,” Rao said.

With their new tracing method, Yang’s group plans to probe how clearance changes across aging, sleep, and disease—and whether brain tumors exploit these pathways to evade immune detection. The architecture of brain waste disposal, once opaque, is now open for exploration.

The post Neuronal Protein Tracing Reveals How the Brain Routes Its Waste appeared first on GEN – Genetic Engineering and Biotechnology News.

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Beyond sunshine: Iberia’s biotech moment has arrived with developing capital networks

Published

1 hour ago

June 12, 2026

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Strong science, lower costs and growing capital networks are putting Spain and Portugal on the biotech investment map, even as structural bottlenecks persist, according to two investors.

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Laser‑Driven Phase Contrast Enhances Cryo‑EM Resolution of Small Proteins

Published

6 hours ago

June 12, 2026

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You know when you are at the eye doctor getting an updated prescription, and suddenly the world snaps into sharper focus? Physicists at the University of California (UC), Berkeley, have now done something similar for electron microscopy. By introducing phase contrast into a cryo‑electron microscope, they have delivered dramatically sharper images of some of biology’s smallest and most elusive proteins.

The advance comes from a new laser phase plate (LPP), described in the paper “Laser phase plate improves structure determination of small proteins by cryo‑EM,” which was published recently in Science. Led by physicist Holger Mueller, PhD, of UC Berkeley and Lawrence Berkeley National Laboratory, the team demonstrated that a laser‑driven phase plate can overcome one of cryo‑EM’s most persistent limitations: poor contrast for small proteins.

Cryo-EM images of two proteins, apoferritin and hemoglobin, taken without and with a laser phase plate. The images are analyzed in a computer to produce detailed 3D structures of the proteins. [Holger Müller, Jessie Zhang/UC Berkeley]

Cryo‑EM has transformed structural biology over the past decade, earning a Nobel Prize in 2017 for enabling high‑resolution structures without crystallization. But despite its impact, the technique still struggles with proteins below ~70 kilodaltons—a size range that includes about 90% of the human proteome. “Because of signal-to-noise limitations, the majority of human and animal proteins are too small to be analyzed by these methods [cryo-EM and cryoelectron tomography]. The increase in signal-to-noise ratio provided by this laser phase plate is expected to overcome these important limitations.”

The new LPP begins to address that problem. The LPP uses an intense, continuous‑wave laser to shift the phase of the electron beam itself. This produces true phase contrast without dimming or destabilizing the beam. Mueller described the laser focus as “75 kilowatts focused to a few microns… That’s more powerful than what you use for welding. It has more power than a military laser. It builds up the brightest continuous laser focus ever.”

Installed in a custom Thermo Fisher Titan Krios, the LPP immediately improved the clarity and resolvability of small proteins, including hemoglobin, which sits at the lower limit of what today’s cryo‑EM instruments can handle. As the authors wrote in the abstract: “Here, we show that the laser phase plate (LPP)… enhances the resolution in single-particle reconstruction of small proteins by improving specimen-motion correction, recovery of information from the early frames, as well as particle visualization, 3D classification, and alignment.”

phase plate cover Cryo-EM — A laser (purple) is powerfully amplified by highly polished mirrors and focused on the electron beam (blue) to shift its phase and increase the cryo-EM microscope’s contrast, allowing biologists to image smaller proteins and the crowded structures inside cells. [Sayo Studio]

These improvements were achieved using standard defocus ranges and reconstruction workflows. “For the most challenging cases—small particles, bad specimens—the laser produces a very considerable advantage,” Mueller said.

The impact extends beyond single‑particle analysis. Cryo‑electron tomography (cryo‑ET), which assembles multiple angular views of a molecule or protein into a three-dimensional image, stands to benefit even more. “With cryo-ET, we’re looking at small, very complicated cellular material that’s incredibly crowded inside the cell,” said Bridget Carragher, PhD, founding technical director of imaging at Biohub. “It’s like a forest of trees, and you’re trying to find one leaf on one tree in there. Cryo-ET needs a dramatic step forward in contrast, so we can start to see what’s going on inside the cell. That’s what the laser phase plate promises to give us.”

Biohub is developing a dual‑laser version of the system, designed to reduce component wear and minimize aberrations. Meanwhile, Mueller’s team is pushing toward imaging proteins as small as 17 kilodaltons, a threshold that would open access to vast regions of the human proteome previously invisible to cryo‑EM.

“This technology is a step function change for biology,” said Stephani Otte, PhD, Biohub’s vice president of imaging science. “What was once invisible will become visible—and that changes everything about how we understand disease.”

“The bottom line is, if you have a large protein and a really good sample—a fresh one or one frozen without bubbles, for example—you may not need the phase plate to get a single, high-quality image. But for a small protein and a bad sample, laser-on is best,” Mueller said. “This could fill an enormous gap in our knowledge of protein structures that can’t be crystallized or are too small for today’s cryo-EM. And it will be revolutionary for cryo-ET.”

The post Laser‑Driven Phase Contrast Enhances Cryo‑EM Resolution of Small Proteins appeared first on GEN – Genetic Engineering and Biotechnology News.

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STAT+: Updated: Tracking RFK Jr.’s promises to remake health in America

Updated June 11, 2026

WASHINGTON — A pledge to “Make America Healthy Again” earned Robert F. Kennedy Jr. his job atop U.S. health agencies a year and some change ago. He’s now had the opportunity to turn his words into action, with mixed results.

“All one needs” to prove the health secretary’s attentiveness is to “review my unprecedented list of accomplishments on a wide range of issues, all of which I drove,” Kennedy posted on X on Wednesday in response to a journalist.

Continue to STAT+ to read the full story…

Published

8 hours ago

June 12, 2026

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