Developmental expression of the axonal glycoprotein TAG-1: differential regulation by central and peripheral neurons in vitro.
TAG-1 is a 135,000 Mr axonal glycoprotein of the immunoglobulin superfamily that promotes axon extension in vitro. One distinguishing feature of TAG-1 is its transient expression on subsets of axons in the developing nervous system. To examine the mechanisms that regulate TAG-1, we have monitored the expression of this protein by developing central and peripheral neurons in vitro. TAG-1 was detected on the surface of a subset of E11 to E13 spinal cord neurons in vitro and was also released by these neurons. Expressions of TAG-1 on the cell surface was transient but it was possible to detect a released form of TAG-1 at all times in vitro. Spinal cord neurons isolated from older embryos did not express surface TAG-1 when they regenerated axons in vitro. Changes in the environment of spinal cord neurons did not alter the time course of TAG-1 expression, suggesting that regulation of the protein is cell autonomous. In contrast to these results with spinal cord neurons, surface expression of TAG-1 by DRG neurons persisted in vitro and adult DRG neurons re-expressed TAG-1 when grown in vitro. The cell surface and released forms of TAG-1 therefore appear to be regulated differently by central and peripheral neurons.
Karagogeos
D
D
Howard Hughes Medical Institute, Department of Biochemistry and Molecular Biophysics, College of Physicians and Surgeons, New York, New York 10032.
Morton
S B
SB
Casano
F
F
Dodd
J
J
Jessell
T M
TM
D000818:Animals; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D015153:Blotting, Western; D015816:Cell Adhesion Molecules, Neuronal; D002454:Cell Differentiation / Q000235:genetics; D002462:Cell Membrane / Q000648:ultrastructure; D002478:Cells, Cultured; D058969:Contactin 2; D005727:Ganglia, Spinal / Q000196:embryology; D005786:Gene Expression Regulation / Q000502:physiology*; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000235:genetics*; D051381:Rats; D013116:Spinal Cord / Q000196:embryology
D015816:Cell Adhesion Molecules, Neuronal; D058969:Contactin 2; D008562:Membrane Glycoproteins