Understanding why the same molecular machinery underlies both early-life neurodevelopmental conditions and late-onset neurodegeneration has long been a puzzle in brain science. A new synthesis of the non-canonical Wnt signaling literature offers a unifying framework — one that could reshape how researchers approach autism spectrum disorder, spina bifida, Alzheimer's disease, and Parkinson's disease simultaneously, rather than treating them as unrelated pathological silos.
This review consolidates evidence on two branches of non-canonical Wnt signaling — the Planar Cell Polarity (Wnt/PCP) pathway and the Wnt/Ca²⁺ pathway — and their respective roles in the developing and adult nervous system. The Wnt/PCP branch governs cytoskeletal reorganization through Rho GTPases, driving neural tube closure, directional neuronal migration, and axon pathfinding. The Wnt/Ca²⁺ branch operates through protein kinase C (PKC), calcium/calmodulin-dependent kinase II (CaMKII), and the transcription factor NFAT to modulate calcium homeostasis and synaptic plasticity. Central to both is Dishevelled (DVL), a multifunctional scaffold protein that acts as a molecular switchboard, routing signals into either canonical β-catenin-dependent or non-canonical effector cascades depending on cellular context. Dysregulation at any point along these axes is linked to defined pathological outcomes across the lifespan.
The broader significance here lies in the convergence: non-canonical Wnt disruption appears not to cause one disease but to set a cellular vulnerability that manifests differently depending on developmental stage and cell type. This contextual sensitivity makes DVL and its downstream effectors attractive but complex therapeutic targets — intervening too broadly risks disrupting normal homeostasis. The review's emphasis on CRISPR/Cas9 and brain organoid platforms is timely, as these tools allow pathway-specific perturbation in human neural tissue for the first time at scale. Critically, this is a narrative review, not a meta-analysis, so causal hierarchies between pathway dysregulation and specific disorders remain correlative. Still, as an organizational framework synthesizing molecular, cellular, and disease-level evidence, it represents a useful map for translational neuroscience.