Persistence of Immunoreactive Neurofilament Protein Breakdown Products in Transected Rat Sciatic Nerve

Abstract

Alterations occurring in nerve proteins of transected nerves were studied in rat sciatic nerves using polyclonal and monoclonal antibodies to identify and monitor neurofilament (NF) epitopes among nerve proteins following their electrophoresis and transfer to nitrocellulose paper. Immunoblot methods identified NF epitopes in NF triplet proteins (Mr 200,000, 150,000, and 68,000) and in NF nontriplet proteins (all other immunobands below Mr 200,000 and above Mr 40,000). NF triplet and nontriplet proteins were Triton-insoluble in both untransected and transected nerves. Extensive loss of NF triplet and most nontriplet proteins occurred during the 24-48-h period following nerve transection and was attributed to proteolytic degradation. Loss of protease-labile NF proteins led to a markedly reduced level of NF immunoreactivity in 2-day transected nerve. NF proteins which survived the 2-day posttransectional period were considered to represent protease-stable NF fragments. These fragments persisted in transected nerve for periods of at least 35 days. Most protease-stable NF fragments which retained immunoreactivity had Mr of 57,000-65,000. Low concentrations of the same immunobands were present in untransected nerves.

Watery and dark axons in Wallerian degeneration of the opossum's optic nerve: different patterns of cytoskeletal breakdown?

“…It is well known that NFs are more resistant to granular disintegration, remaining in the axoplasm for a variable amount of time. Experiments using transection of sciatic nerve of rats (Schlaepfer et al 1984) and mice (Glass and Griffin 1991) showed that NF undergo a slow and progressive redistribution in the distal segment, resulting on accumulations in the distal end of the isolated segment, indicating an incomplete degradation of NF protein during WD (Schlaepfer et al 1984). In the present study we observed many dilated fibers with an accumulation of organelles, NF being particularly abundant in a central position.…”

Differentiation of NTERA-2 clonal human embryonal carcinoma cells into neurons involves the induction of all three neurofilament proteins

“…Figure 5B shows the presence of NF195 and nontriplet NF proteins with molecular weights between 57,000 and 65,000. We have also observed such nontriplet NF proteins derived from NF195 in transected rat sciatic nerves (Schlaepfer et al, 1984). Interestingly, these nontriplet NF proteins were the only NF immunoreactive polypeptides detected in the Triton-soluble fractions prepared from differentiated EC cells; no other IF proteins were detected from this fraction (data not shown).…”

“…Preparation of enriched human NF from spinal cord and cytoskeletal fractions from NT2/DI cells Human NF proteins were prepared from the spinal cord of a 4-hr postmortem infant by a simple one-step procedure, as reported previously (Schlaepfer et al, 1984). In brief, the spinal cord was desheathed and homogenized in a lo-fold dilution (wt/vol) of homogenizing buffer (1% Triton X-100, 1 M sucrose, 2.5 mM EDTA, 2.5 mM EGTA, 100 mM NaCl, and 20 mM sodium phosphate buffer, pH 7.2).…”

Cyclosporin A Affects Axons and Macrophages During Wallerian Degeneration

“…This is turn may slow down the rate of axonal degradation. Typically, axonal transection causes calcium-dependent granular disintegration and a loss of protease-labile proteins (Schlaepfer et al, 1984). Neurofilament immunoreactivity is markedly reduced after 2 days following transection, but protease-stable neurofilaments, which survive the 2-day posttransectional period, persist, at least, 35 days (Schlaepfer et al, 1984).…”