The expression of B-50/GAP-43 in Schwann cells is upregulated in degenerating peripheral nerve stumps following nerve injury.
We have detected mRNA for B-50 (GAP-43, pp46, F1, neuromodulin), which was originally believed to be a neuron-specific protein, in non-neuronal cells in the rat sciatic nerve. In control rats, the level of B-50 mRNA in sciatic nerve tissue was much lower than in dorsal root ganglia. Following nerve crush or transection, the expression of B-50 mRNA in the distal nerve stump increased dramatically between 1 and 2 days post-injury. The B-50 mRNA levels in the distal stump of crushed nerves remained elevated for up to 4 weeks and subsequently returned to control levels after 7 weeks. In contrast, after nerve transection B-50 mRNA levels in the distal nerve portion continued to increase up to 7 weeks post-lesion. No changes in the levels of the B-50 transcript were observed in the proximal portion of either crush-lesioned or transected sciatic nerves. In situ hybridization demonstrated B-50 mRNA associated with Schwann cells in the distal nerve stump. The observation that Schwann cells are capable of producing B-50 mRNA was confirmed by Northern blot analysis of total RNA isolated from primary Schwann cell cultures. Taken together, these data show the expression of B-50 mRNA by Schwann cells and the up-regulation of B-50 mRNA in reactive Schwann cells upon loss of axonal contact.
Plantinga
L C
LC
Rudolf Magnus Institute, Department of Pharmacology, Utrecht University, The Netherlands.
Verhaagen
J
J
Edwards
P M
PM
Hol
E M
EM
Bär
P R
PR
Gispen
W H
WH
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D019922:GAP-43 Protein; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009409:Nerve Crush; D009410:Nerve Degeneration / Q000502:physiology*; D009416:Nerve Regeneration / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D010750:Phosphoproteins / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012583:Schwann Cells / Q000378:metabolism*; D012584:Sciatic Nerve / Q000293:injuries / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology
D019922:GAP-43 Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger