Retrograde axonal transport of locally synthesized proteins, e.g., actin and heat shock protein 70, in regenerating adult frog sciatic sensory axons.
The local synthesis and subsequent retrograde axonal transport of [35S]methionine-labelled proteins was studied in the in vitro regenerating adult frog sciatic sensory axons. By the use of a three compartment culture system, proteins in the outgrowth region were selectively labelled. After 2 days in culture a rise in TCA-insoluble radioactivity was detected in the dorsal root ganglia, which could be prevented by the addition of vinblastine or 2,4-dinitrophenol to the nerve proximal to the crush site. Two-dimensional polyacrylamide gel electrophoresis of ganglionic proteins revealed a pattern of 35 labelled polypeptides with apparent molecular masses (Mm) ranging from < 15 to 95 kDa and with isoelectric points (pI) ranging from 4.5 to 6.5. The major ones, representing about 75% of the activity in a gel, were of Mm/pI 47/5.4, 48/6.1,. 57/6.0, 62/5.2, 65/4.9-5.0, 65/5.2, and 81/5.4 respectively. One of these polypeptides (47/5.4) was identified as actin and another (81/5.4) as a member of the heat shock protein 70 family. The spots at 65/4.9-5.0 were tubulin isoforms. There was a striking similarity between transported proteins on one hand, and proteins synthesized in the injured nerve on the other, with respect to the Mm/pI of at least 14 protein species. The results suggest that a selected set of proteins, synthesized by non-neuronal cells, e.g., Schwann cells, is transferred to the ganglionic cell bodies by retrograde axonal transport.
Edbladh
M
M
Department of Animal Physiology, University of Lund, Sweden.
Ekström
P A
PA
Edström
A
A
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001001:Anura; D001370:Axonal Transport / Q000502:physiology*; D001369:Axons / Q000378:metabolism*; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005724:Ganglia / Q000166:cytology / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D015151:Immunoblotting; D008715:Methionine / Q000378:metabolism; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000502:physiology*; D009475:Neurons, Afferent / Q000378:metabolism*; D012584:Sciatic Nerve / Q000166:cytology / Q000378:metabolism; D013462:Sulfur Radioisotopes
D000199:Actins; D018840:HSP70 Heat-Shock Proteins; D013462:Sulfur Radioisotopes; D008715:Methionine