Architecture of the Norrin signaling complex and structure-guided surrogate design.

A de novo Norrin-FZD4-TSPAN12-LRP5 complex structure shows two curved Norrin homodimers bridging two FZD4-TSPAN12 heterodimers, with LRP5 LA3 coordinating all interfaces.

• Why it matters: Understanding how Norrin signal biogenesis assembles is critical because aberrant signaling is linked to retinopathies, blood-brain barrier defects, and deafness, and mimetics are already in clinical trials.
• What they did: The authors solved the signaling complex structure using a de novo designed FZD4 binder as “protein glue,” then engineered FZD4CRD-LRP5 LA3 bispecific binders as Norrin surrogates and tested them in signaling assays.
• The result: Oligomerization of the Norrin surrogate enhances signaling potency, revealing how the signal is generated and supporting structure-guided development of Norrin/Wnt mimetics.

AI summary of the abstract · may contain errors · not medical advice · read the paper.