SARM1 Acts Downstream of NMNAT2 Loss during Axon Degeneration
(A) Representative immunoblot of uncut (0 hr) and 4-hr-cut wild-type and Sarm1−/− SCG neurite extracts probed for NMNAT2 and β-actin (sample control). NMNAT2 migrates at ∼32 kDa. Quantification of normalized NMNAT2 levels (to β-actin), is shown below with 4-hr data presented relative to uncut (set at 1). Means ± SEM are plotted (n = 3; p = 0.86 wild-type versus Sarm1−/− at 4 hr).
(B) NMN and NAD levels in uncut, and 30-hr- or 120-hr-lesioned wild-type and Sarm1−/− sciatic nerves. Means ± SEM are plotted (n = 3–5). Levels in 120-hr-cut wild-type nerves were not determined (ND) as their axons are degenerated.
(C) Representative images of distal neurites of wild-type and Sarm1−/− SCG neurons 24 and 72 hr after injection with 100 ng/μl Nmnat2 siRNA (siNmnat2) and 10 ng/μl pEGFP-C1 (expressed EGFP allows visualization of the neurites of injected neurons).
(D) Quantification of survival of wild-type (WT) and Sarm1−/− SCG neurites (left) and cell bodies (right) for 3 days after injection with pEGFP-C1 and siNmnat2 or non-targeting siRNA (siNT) as in (C). Means ± SEM are plotted (n = 3–4).