Neurons clean up proteins in their own way
Brain cells dispose of waste proteins differently from other cells in the body. A newly discovered system turns out to be directly linked to hallmarks of Alzheimer’s disease.
Every cell continuously produces, uses and breaks down proteins. When this clearance system fails, damaged or misfolded proteins accumulate. This loss of protein quality control (proteostasis) is one of the earliest and most fundamental processes in brain ageing.
Neurons appear to possess a specialised mechanism that other cell types lack. It involves a variant of the proteasome, a large protein complex that acts as the cell’s waste-processing machinery. This membrane-bound proteasome is anchored in the outer layer of the neuron. The study shows that this system is specifically impaired at central hallmarks of Alzheimer’s disease.
Proteostasis and Alzheimer’s disease
In Alzheimer’s, two types of proteins accumulate: amyloid-beta (clumps outside the cell) and tau (clumps inside the cell). Both have long been recognised as disease markers. What is new is evidence that the membrane-bound proteasome in neurons plays an active role in whether those proteins are cleared or allowed to accumulate. A dysfunctional system makes build-up more likely.
This matters for the question of when Alzheimer’s actually begins. Protein accumulation occurs decades before the first symptoms appear. If the clearance system is already weakening early on, that could be one of the first steps in a very long process.
Why this matters for ageing
With age, proteasome capacity declines across all cell types. In neurons, which unlike many other cells are rarely replaced, that decline is particularly consequential. Cells that do not renew themselves rely entirely on their internal clearance mechanisms. When those mechanisms deteriorate, damaged proteins accumulate without repair.
Identifying this neuron-specific system provides a new therapeutic target. If it becomes possible to restore or boost the activity of the membrane-bound proteasome, damaged proteins could be cleared earlier. That could slow the progression toward Alzheimer’s and reduce the severity of the disease.