Article Figures & Data
Figures
- Figure 1.
A, Immunoblots of extracts of sciatic nerves from intact mice and from nerves cut and repaired one week earlier. IR to AEP (top) is noted by the band at 37 kDa, representing enzymatically active AEP. IR to the AEP-cleaved fragment of Tau (Tau N368) and to full-length Tau (Tau 5) are shown below. B, Quantitative analysis of differences in expression of Tau N368 and Tau 5 between intact nerves and cut and repaired nerves, relative to β actin controls, are shown for a group of male and female mice as mean fold (±SEM) intensities. The horizontal dashed line at unity marks the amount of IR found in intact mice. C, Changes in AEP IR are shown at different times after sciatic nerve transection and repair in WT and AEP KO mice. D, Quantitative analysis of AEP expression in sciatic nerves at different times after nerve transection and repair. Mean (±SEM) fold expression of AEP IR, relative to that found in AEP KO mice at the same postinjury times are shown. The horizontal dashed line at unity marks the amount of IR found in AEP KO mice.
- Figure 2.
A, Immunoblots of extracts of sciatic nerves from intact mice and from nerves cut and repaired one week earlier. IR to an antibody recognizing the product of APP produced by AEP cleavage, APP N585 (top), and full-length APP (bottom) are shown. B, Quantitative analysis of differences in expression of full-length APP (left) and APP N585 (right) between intact nerves and cut and repaired nerves, relative to β actin controls, are shown for a group of male and female mice as mean fold (±SEM) intensities. The horizontal dashed line at unity marks the amount of IR found in Intact mice. C, Time course of expression of APP N585 in cut and repaired sciatic nerves. The horizontal dashed line at unity marks the amount of IR found in AEP KO mice.
- Figure 3.
Neurite length was increased in cultured neurons from AEP−/− mice. A, Examples of neurons cultured from AEP+/+ (top) and AEP−/− (bottom) mice. The identity of longest neurites of individual neurons is indicated by arrows. Scale bar: 100 μm. B, Mean (±SEM) length of the longest neurites in cultures of adult DRG neurons from AEP+/+, AEP+/−, and AEP−/− mice measured at 72 h in vitro.
- Figure 4.
Elongation of regenerating axons is enhanced in AEP KO mice. A, Examples of confocal images of sciatic nerves in SLICK-A mice that had been cut and repaired two weeks earlier with a segment of nerve harvested from a littermate that did not express YFP. Note more longer axons are found in the SLICK-A/AEP−/− mouse (top). B, Distributions of YFP+ regenerating axon profile lengths in male and female SLICK-A/AEP−/− mice (KO:KO) and SLICK-A/AEP+/+ (WT:WT) mice measured two weeks after sciatic nerve transection and repair are shown as cumulative frequency histograms (left). Data from nerves from WT (SLICK-A/AEP+/+) mice repaired with grafts from AEP−/− mice (WT:KO) in comparison to those from WT:WT nerves are shown in the graph on the right. Each set of symbols represents mean values in each bin (N = 5 except for WT:KO, where N = 4). Vertical dashed lines mark the lengths at the 50th percentile, the median for each distribution. C, Average (±SEM) median lengths of regenerating axon profiles two weeks after sciatic nerve transection and repair in mice in which neither, both, or one copy of the gene for AEP had been knocked out, and when WT nerves were repaired with grafts from KO mice (mixed). D, Mean (±SEM) sprouting index in mice of the three genotypes studied and mixed repair nerves. No significant differences were observed.
- Figure 5.
Recovery of evoked muscle responses is accelerated in AEP KO mice. A, Examples of full wave rectified maximal direct muscle (M) responses to sciatic nerve stimulation recorded from GAST muscles at different times after transection and repair of the sciatic nerve. Traces on the left are from a single WT mouse. Those on the right are from a single AEP KO mouse. B, Maximum amplitude M responses were measured in GAST (left) and TA (right) at different times after sciatic nerve transection and repair. Data were fit with linear least-square regression lines. Regression and correlation coefficients are shown for each fitted line. C, Amplitudes of recorded responses in B were scaled to preinjury values in each mouse and re-plotted. Regression and correlation coefficients are shown for each fitted line.
- Figure 6.
A, Effects of ES on recovery of direct muscle (M) response amplitude in AEP KO mice. Mean (±SEM) scaled M response amplitudes recorded from GAST (left) and TA (right) muscles four weeks after sciatic nerve transection and repair. Both AEP KO mice and WT mice were studied. Mice of each genotype either were treated at the time of nerve repair with 1 h of 20-Hz ES of the proximal nerve stump or left untreated. B, Effects of ES on BDNF-TrkB expression in WT and AEP KO mice. Immunoblots from sciatic nerves 7 d following nerve transection and repair were probed for two markers of BDNF-TrkB signaling: phosphorylation of the TrkB receptor at Y816 and phosphorylation of the downstream effector, AKT. IR to both is increased in ES mice relative to untreated (UT) controls in both WT and AEP KO animals. C, Effects of ES on AEP cleavage of APP and Tau. Immunoblots from animals used in panel C were probed with antibodies to AEP, full-length APP and Tau, and the AEP cleavage products of these two proteins, APP N585 and Tau N368. The solid arrow points to the greater amount of IR to inactive AEP in the ES mouse.
In this issue
