Characterization of the Injury Response of Ciliated Neurons in Drosophila
Restricted (Penn State Only)
- Author:
- Mauger, Abigail
- Area of Honors:
- Biochemistry and Molecular Biology
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Melissa Rolls, Thesis Supervisor
Santhosh Girirajan, Thesis Honors Advisor - Keywords:
- axon injury
ciliated neurons
chordotonal
DLK
axon regeneration
Drosophila
neuron
axon - Abstract:
- Axon regeneration is a well-characterized response to axon injury that maintains the peripheral nervous system. Drosophila melanogaster is an ideal model to study axon regeneration because it is genetically tractable and the larval sensory neurons are amenable to imaging in vivo. Sensory neurons with branched dendrites have been shown to regenerate from the axon stump or from converted dendrites after axon injury. However, both insects and vertebrates have neurons that lack branched dendrites and instead have specialized cilia that respond to sensory stimuli. In contrast to neurons with branched dendrites, ciliated sensory neurons cannot convert a dendrite into an axon when the axon stump is too short to support axon outgrowth. To investigate the axon injury response of ciliated neurons, the axons of Drosophila larval chordotonal (Cho) neurons were severed in vivo using a pulsed UV laser and fluorescence microscopy. After distal axon injury, when the axon stump was long, Cho neurons regenerated from the axon stump. After proximal axon injury, Cho neurons regenerated branching neurites from the cell body or axon stump. To determine whether these neurites were axons, the microtubule polarity and ER localization in the regenerating neurites was examined. The results of these experiments suggest that some neurites or portions of neurites have characteristics consistent with axons. To investigate whether Cho neurons rely on the typical axon injury signaling pathway initiated by dual leucine zipper kinase (DLK), the expression of puckered (puc), a reporter of DLK pathway activation, was assessed after injury and RNAi was used to knock down expression of DLK. Increased puc expression indicated that the DLK pathway was activated, and regeneration was reduced by DLK RNAi. These results suggest that Cho neurons use the typical axon injury signaling pathway.