Axonal signals regulate expression of glia maturation factor-beta in Schwann cells: an immunohistochemical study of injured sciatic nerves and cultured Schwann cells.
Glia maturation factor-beta (GMF-beta) is a 17 kDa protein purified and sequenced from bovine brains. Using the monoclonal antibody G2-09 directed against GMF-beta, we previously demonstrated endogenous GMF-beta in astroblasts, Schwann cells, and their tumors in culture. In the present study, we have used indirect immunofluorescence microscopy with G2-09 to examine the effects of transection, crush, and regeneration of sciatic nerve on the expression of GMF-beta in Schwann cells in situ and to study the time course of GMF-beta induction in Schwann cells in vitro. For comparison, a parallel study was carried out with monoclonal antibodies directed against nerve growth factor (NGF) receptor. We found that (1) neither GMF-beta nor NGF receptor was detectable in intact sciatic nerves, (2) all Schwann cells of the distal segment of the transected nerve expressed GMF-beta as early as 3 d after axotomy that persisted up to 3 weeks, (3) axonal regeneration repressed the Schwann cell expression of GMF-beta, (4) isolated Schwann cells derived from rat sciatic and adult human sural nerves developed intracellular GMF-beta in culture following an initial lag period, and (5) the induction of Schwann cell NGF receptor coincided temporally with that of GMF-beta in the transected nerve and in culture. These results show that the expression of GMF-beta in Schwann cells, as is the case with the NGF receptor, is induced by the loss of the normal axon-Schwann cell contact. We propose that the induction of GMF-beta, as well as NGF receptor, in Schwann cells after nerve injury plays a role in axonal regeneration.
Bosch
E P
EP
Department of Neurology, University of Iowa College of Medicine, Iowa City.
Zhong
W
W
Lim
R
R
D000818:Animals; D001369:Axons / Q000502:physiology*; D002478:Cells, Cultured; D005260:Female; D020904:Glia Maturation Factor; D006133:Growth Substances / Q000378:metabolism; D007150:Immunohistochemistry; D009409:Nerve Crush; D009416:Nerve Regeneration; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012583:Schwann Cells / Q000378:metabolism / Q000502:physiology*; D012584:Sciatic Nerve / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D014018:Tissue Distribution
D020904:Glia Maturation Factor; D006133:Growth Substances; D009419:Nerve Tissue Proteins