Brain cells constantly pull material from the fluid around them. They need nutrients, signals, and tiny pieces of their own outer layer. This pulling process is called endocytosis. It helps with learning, memory, and everyday cell upkeep.
Researchers at Penn State have found a hidden structure that may control most of this activity. The structure is a tiny lattice just under the cell membrane. It is called the membrane‑associated periodic skeleton, or MPS.
A Hidden Gatekeeper Inside Neurons
In a study published in Science Advances, scientists showed that the MPS works like a gatekeeper for nearly every type of endocytosis. The lattice is made of repeating rings of protein. Earlier work said it only helped keep neurons in shape. New data reveal that it also decides where and when substances can enter the cell.
The MPS was first spotted in 2013 by a researcher named Zhou. Back then, it was thought to be a passive support scaffold. Using super‑resolution microscopes, Zhou’s team watched living neurons and saw the lattice acting like traffic control, guiding all major endocytic pathways.
Seeing Cell Uptake at the Nanoscale
Super‑resolution microscopy can see details ten thousand times smaller than a human hair. The scientists grew neurons in petri dishes and tagged specific proteins so they could follow them inside the cells.
They then exposed the neurons to different molecules and recorded how the cells took them in while the MPS stayed intact. When they damaged parts of the lattice, the cells began to swallow material much faster. This showed that the lattice normally slows the process and prevents over‑absorption.
The team also discovered a feedback loop. Faster endocytosis weakened the lattice, which opened more entry points, allowing even more nutrients and proteins to flow in.
"The membrane skeleton actively regulates nutrient uptake," said Zhou. "It acts like a gatekeeper, keeping the barrier closed until the neuron needs a specific nutrient, then opening the gates. "
Possible Link to Alzheimer’s Disease
To test a disease connection, the researchers created a model that mimics early Alzheimer’s. They made neurons produce extra amyloid precursor protein (APP), a key molecule linked to the disease.
When the MPS was weakened, neurons took in APP more quickly. Inside the cell, APP was cut into amyloid‑β42, a toxic fragment that builds up in Alzheimer’s brains. Damaged neurons accumulated more of this toxin and showed signs of cell death.
A New Target for Treatment
The findings suggest the MPS acts as a protective barrier. By slowing APP entry, it may limit the buildup of harmful proteins. Because the lattice naturally deteriorates with age, its loss could trigger a vicious cycle: more toxic protein, more lattice damage, and eventual neuron death.
Stabilizing or protecting the MPS could become a new way to slow neurodegeneration. Researchers hope this insight will guide future therapies aimed at the early, hidden changes that precede Alzheimer’s symptoms.