The Cytoplasmic Domain of the Drosophila Cell Adhesion Molecule Neuroglian Is Not Essential for Its Homophilic Adhesive Properties in S2 Cells

doi:10.1074/jbc.270.32.18809

The Cytoplasmic Domain of the Drosophila Cell Adhesion Molecule Neuroglian Is Not Essential for Its Homophilic Adhesive Properties in S2 Cells (*)

From the (1) Department of Anatomy and Cell Biology, University of Michigan, Ann Arbor, Michigan 48109 and the
(2) Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907

^§ To whom correspondence should be addressed:
Dept. of Anatomy and Cell Biology, University of Michigan, Ann Arbor, MI 48109-0616.
Tel.: 313-747-2720; Fax: 313-763-1166.

Abstract

Drosophila neuroglian is a transmembrane glycoprotein that has strong structural and sequence homology to the vertebrate L1 gene family of cell adhesion molecules (Bieber, A. J., Snow, P. M., Hortsch, M., Patel, N. H., Jacobs, J. R., Traquina, Z. R., Schilling, J., and Goodman, C. S.(1989) Cell 59, 447-460). Two different neuroglian protein forms that are generated by a differential splicing process are expressed in a tissue-specific fashion by embryonic and larval cells (Hortsch, M., Bieber, A. J., Patel, N. H., and Goodman, C. S. (1990) Neuron 4, 697-709). The two neuroglian polypeptides differ only in their cytoplasmic domains. Both of these neuroglian species, when transfected into and expressed in Drosophila S2 cells, induce the calcium-independent, homophilic aggregation of transformed cells. A third artificial neuroglian protein form was constructed by substituting the neuroglian transmembrane segment and cytoplasmic domains with the glycosyl phosphatidylinositol attachment signal of the Drosophila fasciclin I protein. This cDNA construct generates a glycosyl phosphatidylinositol-anchored form of neuroglian, which retains the ability to induce homophilic cell aggregation when expressed in S2 cells, and was able to interact with both of the two naturally occurring neuroglian polypeptides. These results demonstrate that neuroglian mediates a calcium-independent, homophilic cell adhesion activity and that neither cytoplasmic neuroglian domains nor a direct interaction with cytoskeletal elements is essential for this property.

Footnotes

↵* The work presented in this manuscript was supported in part by grants from the University of Michigan Cancer Center (Institutional Grant from the American Cancer Society) and the National Institutes of Health (Grant HD29388 to M. H.) and by grants from the National Science Foundation (Grant IBN-9120981), the American Cancer Society (Grant IRG IN-17), the Purdue Research Foundation, and the Showalter Foundation (to A. B.) The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

CAM

cell adhesion molecule

DiI

1,1′-dioctadecyl-3,3,3′-tetramethylindocarbocyanine perchlorate

GPI

glycosyl phosphatidylinositol

PI-PLC

phosphatidylinositol phospholipase C

PCR

polymerase chain reaction

PECAM

platelet/endothelial cell adhesion molecule

NCAM

neural cell adhesion molecule

Nr-CAM

Ng-CAM related cell adhesion molecule

Ng-CAM

neuron-glia cell adhesion molecule.
↵²M. Hortsch, unpublished results.
↵³M. Seeger, personal communication.
↵⁴R. R. Dubreuil, G. MacVicar, S. Dissanayake, C. Liu, D. Homer, and M. Hortsch, submitted for publication.
- Received January 25, 1995.
- Revision received May 23, 1995.