Neurite

Internal medicine

Pathology

Neuroscience

Disease

Phosphatidylserine

Drosophila melanogaster

Neuronal degeneration

Membrane

Biology

Gene

Psychoanalysis

Psychology

In vitro

Drosophila (subgenus)

Phospholipid

Degeneration (medical)

Externalization

Cell biology

Genetics

Medicine

Cell Reports

Phagocytic clearance of degenerating dendrites or axons is critical for maintaining tissue homeostasis and preventing neuroinflammation. Externalized phosphatidylserine (PS) has been postulated to be an "eat-me" signal allowing recognition of degenerating neurites by phagocytes. Here we show that in Drosophila, PS is dynamically exposed on degenerating dendrites during developmental pruning and after physical injury, but PS exposure is suppressed when dendrite degeneration is genetically blocked. Ectopic PS exposure via phospholipid flippase knockout and scramblase overexpression induced PS exposure preferentially at distal dendrites and caused distinct modes of neurite loss that differ in larval sensory dendrites and in adult olfactory axons. Surprisingly, extracellular lactadherin that lacks the integrin-interaction domain induced phagocyte-dependent degeneration of PS-exposing dendrites, revealing an unidentified bridging function that potentiates phagocytes. Our findings establish a direct causal relationship between PS exposure and neurite degeneration in vivo.

Phosphatidylserine Externalization Results from and Causes Neurite Degeneration in Drosophila