Wnt-Calcium Signaling Pathway Controls Developmental Neurite Pruning in C. elegans
Researchers using the PDB motor neuron in C. elegans have identified that the Wnt-calcium signaling pathway is required for stereotyped neurite pruning during development. The study found that the Wnt ligand LIN-44 acts upstream of calcium-dependent kinases UNC-43/CaMKII and PKC-2/PKC, with PKC-2 regulating pruning through clathrin-mediated endocytosis. The findings are significant because human CaMKIIA can substitute for the worm protein, and mutations in human CaMKII genes linked to intellectual disabilities impair this pruning function.
A new study published on bioRxiv demonstrates that the Wnt-calcium signaling pathway plays a critical role in developmentally regulated neurite pruning, using the PDB motor neuron of the nematode C. elegans as a model. Mutants lacking functional itr-1/IP3 receptor, unc-43/CaMKII, or pkc-2/PKC all exhibited neurite pruning defects, and genetic epistasis analysis placed these components downstream of the Wnt ligand lin-44. In vivo calcium imaging confirmed that PDB neurites display calcium transients during the pruning process, and these transients are at least partially regulated by lin-44 and itr-1. The researchers further showed that PKC-2 mediates pruning through clathrin-mediated endocytosis, suggesting a mechanism by which calcium signaling is translated into cytoskeletal or membrane remodeling events. Notably, human CaMKIIA was able to rescue pruning defects in C. elegans mutants, and disease-associated mutations in human CaMKII genes found in patients with intellectual disabilities disrupted this rescue, pointing to potential clinical relevance. The work addresses a gap in understanding non-activity-dependent, stereotyped forms of neurite pruning, which are less well characterized than activity-dependent pruning.
What's missing
As a preprint, this study has not yet undergone peer review, so its findings should be interpreted with caution. The study does not address whether the Wnt-calcium pruning mechanism identified in C. elegans operates in mammalian neurons in vivo, nor does it clarify the precise downstream targets of PKC-2 within the clathrin-mediated endocytosis pathway. The causal link between CaMKII mutations in human intellectual disability patients and defective neurite pruning in the brain remains correlative at this stage.
What different sources said
- bioRxivCenter
LIN-44/Wnt controls developmental neurite pruning via UNC-43/CaMKII and PKC-2/PKC in C. elegans
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