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Researchers have identified a previously unknown type of brain cell called E2 ependymal cells that line the fluid-filled cavities of the brain in mice and humans. Unlike typical ependymal cells with many cilia that move cerebrospinal fluid, E2 cells possess only one or two specialized cilia that appear to function as sensory antennae, detecting signaling molecules like Sonic Hedgehog in the cerebrospinal fluid. These cells have distinctive structural features including an unusually large basal body and are concentrated in brain regions with high fluid flow and active neurogenesis.
Why it matters
This discovery provides a cellular mechanism for how the brain detects and responds to signaling molecules in cerebrospinal fluid, which could be important for understanding brain development, neurogenesis in adults, and potentially developing therapeutic approaches for neurological conditions that involve disrupted cerebrospinal fluid signaling.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Ependymal (E1) cells, with their tufts of ~50 motile cilia, line the walls of the brain ventricles and help propel the cerebrospinal fluid (CSF). The CSF is rich in signaling molecules, but the cellular targets that detect these signals and their function remain unknown. Here, we describe a distinct population of ependymal cells (E2) in the forebrain of mice and humans, the majority having only 1 or 2 cilia. These cilia were motile, but unlike E1 cells cilia, their pattern of motility and high expression of Arl13b and Inpp5e suggest a sensory function. E2 cells were characterized by an enormous, donut-like basal body that contained an increased number and size of subdistal appendages. In mice, E2 cells were mostly born in the embryo, but completed their differentiation in juveniles and young adults; they were found at higher densities in regions of high CSF flow and neurogenesis. E2 cilia contained the G protein-coupled receptor Smoothened, which accumulated in their cilia upon exposure to Sonic Hedgehog (Shh). Together, these findings identify E2 cells as a novel CSF-sensing ependymal cell type and provide a cellular target for the CSF signaling.