Schwann cells stimulated by axolemma-enriched fractions express cyclic AMP responsive element binding protein.
Both axolemma-enriched fractions (AEF) and cyclic AMP have been shown to regulate the proliferation and differentiation of cultured primary Schwann cells (SC). We have evaluated the role of CREB, a transcription factor that binds to the cAMP-responsive element, in mediating the AEF-stimulated SC proliferation and differentiation. We detected CREB in nuclear extracts derived from SC stimulated with 40 micrograms/ml of AEF for 16, 24, 48, 72, and 96 hr, using a DNA-electrophoretic mobility shift assay. Unstimulated quiescent SC contained low levels of CREB which increased to a maximal level after 48 hr of AEF treatment. Using anti-CREB antibodies and Western blot analysis, after 24 hr of AEF treatment we first detected CREB as a 45 kDa protein which reached a maximal level of expression after 72 hr. Double labeled immunocytochemistry using anti-CREB and anti-5-bromo-2'-deoxy-uridine antibodies demonstrated maximal CREB expression after 72 hr of AEF treatment, closely coinciding with the temporal expression of SC proliferation. At all times examined, all AEF-treated SC labeled by anti-CREB antibodies were also labeled with anti-BrdU antibodies. These observations are consistent with the view that CREB could play an important role in the induction of SC proliferation by AEF.
Lee
M M
MM
Department of Cell Biology, Neurobiology, and Anatomy, Loyola University Medical Center, Maywood, Illinois, USA.
Sato-Bigbee
C
C
De Vries
G H
GH
D000818:Animals; D001369:Axons / Q000378:metabolism*; D015153:Blotting, Western; D002455:Cell Division / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000096:biosynthesis*; D004247:DNA / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D007150:Immunohistochemistry; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012583:Schwann Cells / Q000187:drug effects / Q000378:metabolism*; D013268:Stimulation, Chemical; D015854:Up-Regulation / Q000187:drug effects
D017362:Cyclic AMP Response Element-Binding Protein; D009687:Nuclear Proteins; D004247:DNA