The Brain’s Support Cells Have Hidden Controls, Scientists Just Mapped Them
Astrocytes make up roughly half the cells in the human brain and do far more than support neurons.
A study published in Science uses a technique called in vivo Perturb-seq: systematically switching transcription factors — the proteins that determine which genes are active — on and off in astrocytes of living mice, then measuring what changes inside each cell. The output is a functional map of how astrocytes are regulated.
Astrocytes account for roughly half of all cells in the brain. They maintain the blood-brain barrier, supply neurons with nutrients, clear waste products, and play a central role in inflammatory responses. In neurodegenerative diseases like Alzheimer’s, Parkinson’s, and ALS, astrocytes enter a so-called reactive state: they change shape and behavior in ways that can be protective but also damaging. Exactly how and why that transition happens has been poorly understood.
A circuit diagram for brain support cells
The Perturb-seq approach allows that question to be answered systematically. By disabling transcription factors one at a time and measuring which genes fall silent, the researchers reconstructed which factors control specific astrocyte functions. Some factors turn out to be responsible for the reactive state seen in Alzheimer’s pathology. Others regulate astrocyte energy metabolism, which is relevant to how the brain handles oxidative stress — a process that accelerates with age.
The study is methodologically ambitious. Combining genetic manipulation with single-cell RNA sequencing in living brain tissue is technically demanding. But the approach yields a level of detail that earlier studies couldn’t provide. Rather than treating astrocytes as a homogeneous group, the map reveals substantial diversity in how individual astrocytes respond to the same molecular signals.
Can this be translated into treatment?
The practical question is this: if a specific transcription factor drives astrocytes into a harmful reactive state, can that factor be therapeutically inhibited? In principle, yes. In practice, selectively targeting transcription factors in human brain cells is among the hardest challenges in neurology. But having a detailed map is the necessary first step. Without it, potential therapeutic targets are largely guesswork.