Jo, H.-N. | bioRxiv Science

bioRxiv2026

A FZD4/LRP5 agonist restores pericyte coverage and vascular integrity by increasing PDGFB signaling

Pericytes, specialized mural cells of capillaries, fulfill crucial physiological functions including promoting endothelial barrier function and regulating angiogenesis. Pericyte loss or dysfunction represents a central pathological feature in diabetic retinopathy (DR) and is increasingly recognized in neurodegenerative diseases as well as in poor stroke outcomes, underscoring an urgent need for therapies that restore pericyte function or promote their regeneration. Here, we utilized a Frizzled4 (FZD4) and Low-Density Lipoprotein Receptor-Related Protein 5 (LRP5) agonist antibody (F4L5.13) to investigate the functional consequences of mimicking {beta}-catenin-dependent signaling in CNS endothelial cells (ECs), which is physiologically induced by Norrin or WNT7A/B. In platelet-derived growth factor subunit B (Pdgfb) EC-specific knockout (ECKO) mice, a model of severe developmental pericyte deficiency with secondary blood-retina barrier (BRB) defects and hemorrhages, F4L5.13 significantly promoted retinal pericyte/mural cell proliferation and coverage, improved BRB function, reduced hemorrhages, and normalized vascular morphology. F4L5.13 restored Pdgfb mRNA expression levels from non-recombined cells in Pdgfb ECKO retinas. These findings highlight interactions of {beta}-catenin-dependent signaling and PDGFB production, identify a key pharmacodynamic action of F4L5.13 distinct from anti-VEGF therapies, and suggest that FZD4/LRP5 agonists may have uses as a regenerative pharmacology approach that promotes pericyte coverage in the neurovascular unit.

developmental biology↗

bioRxiv2025

The Calcium Pump ATP2B1/PMCA1 Regulates CNS Vascular Development by Facilitating Norrin- and WNT7A/B-induced Frizzled4 signaling

Frizzled4 (FZD4) is a receptor for Norrin and WNT7A/B ligands, is expressed in endothelial cells (ECs), is required for endothelial blood-central nervous system (CNS) barrier function as well as CNS angiogenesis, and transduces {beta}-catenin-dependent signaling. Despite its fundamental importance in neurovascular biology, including as a drug target, the molecular mechanisms governing FZD4 regulation remain poorly understood. Here, we employed proximity biotinylation to identify proteins that regulate FZD4. We identified ATPase Plasma Membrane Ca{superscript 2} Transporting 1 (ATP2B1, also known as PMCA1) as a FZD4 proximity interactor. Functional analyses revealed that ATP2B1 depletion increased EC Ca2+, activated NFAT, and significantly attenuated Norrin/Frizzled4 signaling. Endothelial-specific Atp2b1 deletion caused CNS vascular phenotypes consistent with compromised Norrin/Frizzled4 signaling. This study identifies ATP2B1 as a novel regulator of Norrin- and WNT7A/B-induced FZD4 signaling and suggests that in pathological contexts with elevated EC Ca2+-levels, EC function may be modulated by suppression of {beta}-catenin-dependent signaling.

developmental biology↗