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Ran‐2, a glial lineage marker, is a GPI‐anchored form of ceruloplasmin
Author(s) -
Salzer James L.,
Lovejoy Laura,
Linder Maria C.,
Rosen Charles
Publication year - 1998
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/(sici)1097-4547(19981015)54:2<147::aid-jnr3>3.0.co;2-e
Subject(s) - schwann cell , ceruloplasmin , microbiology and biotechnology , biology , phosphatidylinositol , membrane protein , antigen , immunoprecipitation , neuroglia , monoclonal antibody , antibody , signal transduction , immunology , biochemistry , central nervous system , neuroscience , membrane
Cell interactions in the nervous system are frequently mediated by surface proteins that are attached to the membrane by a glycosyl phosphatidylinositol (GPI) anchor. In this study, we have characterized the expression of such proteins on glial cells. We have detected a major GPI‐anchored protein on astrocytes and Schwann cells, with a molecular weight of 140 kD. When Schwann cells were treated with forskolin to promote a myelinating phenotype, expression of this 140‐kD protein dramatically decreased, whereas another GPI‐anchored protein of 80 kD was strongly induced; expression of other integral membrane proteins were likewise dramatically altered. The size and pattern of expression of the 140‐kD protein suggested that it might correspond to the Ran‐2 antigen, a glial lineage marker. This notion was confirmed by immunoprecipitating this 140‐kD protein with the Ran‐2 monoclonal antibody. The Ran‐2 antigen is expressed over the entire Schwann cell surface in a punctate fashion; it is removed by phosphatidylinositol phospholipase C treatment, thereby confirming that it is GPI‐anchored. When Schwann cells are cocultured with neurons, the Ran‐2 antigen initially concentrates at sites of Schwann cell contact with neurons, suggesting that it may play a role in early Schwann cell–neuron interactions; it is then downregulated. Protein sequencing of the Ran‐2 antigen immunopurified from rat brain membranes showed complete identity over two extended segments with the copper binding protein ceruloplasmin. These findings indicate that astrocytes and Schwann cells express a novel GPI‐anchored form of ceruloplasmin and suggest that this GPI form plays a role in axonal–glial interactions. J. Neurosci. Res. 54:147–157, 1998. © 1998 Wiley‐Liss, Inc.