Increased P0 glycoprotein gene expression in primary and transfected rat Schwann cells after treatment with axolemma-enriched fraction.
To elucidate the role of axonal plasma membrane factors in the differentiation of Schwann cells, we investigated the effect of an axolemma-enriched fraction (AEF) isolated from myelinated CNS tissue on the expression of P0 glycoprotein, the major glycoprotein in peripheral myelin, in primary rat Schwann cells (PSC) isolated from sciatic nerve, as well as in a transfected rat Schwann cell line (TSC). AEF increased PO-mRNA levels in PSC and TSC in a concentration-dependent manner, producing a maximal induction of nearly twofold after 48 hr of treatment. A similar induction of P0 mRNA was elicited in TSC by the cAMP-activating agents 8-bromo-cAMP and forskolin, which have been shown to induce myelin proteins in PSC. In addition to inducing P0 mRNA, AEF and forskolin also increased the amount of P0 protein in TSC, as indicated by increased P0-immunoreactive staining. However, in TSC, axolemma caused no increase in expression of CAT linked to a P0 promoter while forskolin caused a marked increase in the expression from the P0 promoter. These results suggest that AEF, in contrast to forskolin, does not regulate P0-mRNA expression at the level of transcriptional activity. These in vitro systems may be useful for the study of axolemmal factors that induce Schwann cell differentiation.
Knight
R M
RM
Department of Biochemistry and Molecular Biophysics, Medical College of Virginia, Richmond 23298-0614.
Fossom
L H
LH
Neuberger
T J
TJ
Attema
B L
BL
Tennekoon
G
G
Bharucha
V
V
DeVries
G H
GH
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000502:physiology; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D015342:DNA Probes; D015870:Gene Expression; D007425:Intracellular Membranes / Q000502:physiology; D007700:Kinetics; D008862:Microsomes, Liver / Q000502:physiology; D018993:Myelin P0 Protein; D009185:Myelin Proteins / Q000096:biosynthesis / Q000235:genetics*; D009186:Myelin Sheath / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D012583:Schwann Cells / Q000187:drug effects / Q000378:metabolism*; D012584:Sciatic Nerve / Q000378:metabolism; D014162:Transfection
D015816:Cell Adhesion Molecules, Neuronal; D015342:DNA Probes; D018993:Myelin P0 Protein; D009185:Myelin Proteins; D012333:RNA, Messenger; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate