Mitochondria Drive Neuron Pruning in Fruit Flies
Researchers found that mitochondria and cell-death proteins are required for the removal of unneeded dendrites in fruit fly sensory neurons.
Updated on Nov. 3, 2026 in Alzheimer’s
Researchers showed that mitochondria are required for caspase activation and branch severing in Drosophila sensory neurons, and that the proapoptotic proteins Reaper, hid and grim are needed for dendrite pruning. The work used a dual-colour caspase probe to track activity in a single class IV neuron during metamorphosis.
Why it matters
The findings suggest that the machinery of cell death is repurposed inside living neurons to reshape their connections without killing them. Understanding how neurons trim branches may inform research into how neural circuits are maintained and remodelled.
Caspase substrates were cleaved in the ddaC neuron within 20 minutes of puparium formation, at levels consistently lower than in dying neighbouring neurons. Whether this pruning mechanism operates in vertebrate neurons is not addressed in the study.
The details
Using single-cell mutant clones, the researchers found that Reaper, hid and grim are cell-autonomously required for dendrite pruning in the ddaC neuron. Disrupting mitochondrial function or transport depleted dendritic mitochondria, prevented caspase activation, and blocked both pruning and apoptosis in neighbouring class III neurons.
Timeline
Within 20 minutes of puparium formation, caspase substrates are cleaved in the ddaC neuron.
At the onset of Drosophila metamorphosis, class III neurons die by apoptosis while ddaC prunes its dendrites.
Big Picture
This study extends the established Drosophila class IV da neuron model of dendrite pruning, in which ddaC removes larval branches before regrowing an adult arbor. It adds mitochondria as a required upstream component of the caspase pathway that severs those branches.
The findings are preclinical and based on fruit fly neurons, so they do not change current treatment options. They may inform future research into how neurons maintain their connections.
The takeaway
Cell-death machinery can be repurposed inside living neurons to trim connections without killing the cell. This points to a mechanism that could matter for understanding how neural circuits are reshaped.
Further reading
Explore more on Alzheimer’s research and the neuronal mechanisms that underlie it.
Source note: This article includes information reported by Nature.
