JNK-Interacting Protein 3 Mediates the Retrograde Transport of Activated c-Jun N-Terminal Kinase and Lysosomes
(A) Schematic and time-line of the injury model experiment and fluorescent intensity quantification. pLL nerve (identified using the neurod:EGFP transgene) was severed using finely pulled glass capillaries. DIC image of a representative injury illustrates peripheral tissue remained mostly intact. Three hours post-injury, larvae were fixed and stained for GFP (to identify the nerve) and either pJNK or tJNK. Thirty µm areas immediately proximal or distal to the injury were imaged and the mean fluorescent intensity of pJNK or tJNK was determined in summed projected stacks through the nerve only in areas that overlapped with GFP expression (outlined by dotted lines in B–I). Background mean fluorescent intensity was determined in adjacent tissue. (B–I) Proximal and distal nerve (dotted outline) adjacent to site of injury (dashed line) in wildtype and jip3nl7 larvae immunolabled for pJNK (B–E) and tJNK (F–I). (J) Levels of pJNK were decreased distal to nerve injury in jip3nl7 but proximal levels were comparable to wildtype (ANOVA, post-hoc contrasts; *-p<0.05). (K) tJNK levels trended towards a decrease proximal to the site of injury in jip3nl7 (ANOVA, post-hoc contrasts; p<0.1790) but were not different in the retrograde pool, distal to axonal severing.