Probes for WNT5A

The choroid plexus (ChP) produces cerebrospinal fluid and forms an essential brain barrier. ChP tissues form in each brain ventricle, each one adopting a distinct shape, but remarkably little is known about the mechanisms underlying ChP development. Here, we show that epithelial WNT5A is crucial for determining fourth ventricle (4V) ChP morphogenesis and size in mouse. Systemic Wnt5a knockout, or forced Wnt5a overexpression beginning at embryonic day 10.5, profoundly reduced ChP size and development. However, Wnt5a expression was enriched in Foxj1-positive epithelial cells of 4V ChP plexus, and its conditional deletion in these cells affected the branched, villous morphology of the 4V ChP. We found that WNT5A was enriched in epithelial cells localized to the distal tips of 4V ChP villi, where WNT5A acted locally to activate non-canonical WNT signaling via ROR1 and ROR2 receptors. During 4V ChP development, MEIS1 bound to the proximal Wnt5a promoter, and gain- and loss-of-function approaches demonstrated that MEIS1 regulated Wnt5a expression. Collectively, our findings demonstrate a dual function of WNT5A in ChP development and identify MEIS transcription factors as upstream regulators of Wnt5a in the 4V ChP epithelium.

The complexity of signaling events and cellular responses unfolding in neuronal, glial, and immune cells upon traumatic brain injury (TBI) constitutes an obstacle in elucidating pathophysiological links and targets for intervention. We use array phosphoproteomics in a murine mild blunt TBI to reconstruct the temporal dynamics of tyrosine-kinase signaling in TBI and then scrutinize the large-scale effects of perturbation of Met/HGFR, VEGFR1, and Btk signaling by small molecules. We show Met/HGFR as a selective modifier of early microglial response and that Met/HGFR blockade prevents the induction of microglial inflammatory mediators, of reactive microglia morphology, and TBI-associated responses in neurons and vasculature. Both acute and prolonged Met/HGFR inhibition ameliorate neuronal survival and motor recovery. Early elevation of HGF itself in the cerebrospinal fluid of TBI patients suggests that this mechanism has translational value in human subjects. Our findings identify Met/HGFR as a modulator of early neuroinflammation in TBI with promising translational potential.

The choroid plexus (ChP) in each brain ventricle produces cerebrospinal fluid (CSF) and forms the blood-CSF barrier. Here, we construct a single-cell and spatial atlas of each ChP in the developing, adult, and aged mouse brain. We delineate diverse cell types, subtypes, cell states, and expression programs in epithelial and mesenchymal cells across ages and ventricles. In the developing ChP, we predict a common progenitor pool for epithelial and neuronal cells, validated by lineage tracing. Epithelial and fibroblast cells show regionalized expression by ventricle, starting at embryonic stages and persisting with age, with a dramatic transcriptional shift with maturation, and a smaller shift in each aged cell type. With aging, epithelial cells upregulate host-defense programs, and resident macrophages upregulate interleukin-1β (IL-1β) signaling genes. Our atlas reveals cellular diversity, architecture and signaling across ventricles during development, maturation, and aging of the ChP-brain barrier.