Cysteine Proteinase-1 and Cut Protein Isoform Control Dendritic Innervation of Two Distinct Sensory Fields by a Single Neuron

• Drosophila ddaC sensory neurons elaborate 2 distinct dendritic trees via remodeling
• Expression screen identifies protease Cp1 as a key regulator of dendrite regeneration
• Cp1 controls production of distinct Cut protein isoform, needed for dendrite regrowth
• Induced by hormone, Cp1 ties extracellular cues to dendritic/sensory field plasticity

SummaryDendrites often exhibit structural changes in response to local inputs. Although mechanisms that pattern and maintain dendritic arbors are becoming clearer, processes regulating regrowth, during context-dependent plasticity or after injury, remain poorly understood. We found that a class of Drosophila sensory neurons, through complete pruning and regeneration, can elaborate two distinct dendritic trees, innervating independent sensory fields. An expression screen identified Cysteine proteinase-1 (Cp1) as a critical regulator of this process. Unlike known ecdysone effectors, Cp1-mutant ddaC neurons pruned larval dendrites normally but failed to regrow adult dendrites. Cp1 expression was upregulated/concentrated in the nucleus during metamorphosis, controlling production of a truncated Cut homeodomain transcription factor. This truncated Cut, but not the full-length protein, allowed Cp1-mutant ddaC neurons to regenerate higher-order adult dendrites. These results identify a molecular pathway needed for dendrite regrowth after pruning, which allows the same neuron to innervate distinct sensory fields.

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