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Functional characterization of NCAM fibronectin type III domains: Demonstration of modulatory effects of the proline‐rich sequence encoded by alternatively spliced exons a and AAG
Author(s) -
Kasper Christina,
Stahlhut Martin,
Berezin Vladimir,
Maar Thomas E.,
Edvardsen Klaus,
Kiselyov Vladislav V.,
Soroka Vladislav,
Bock Elisabeth
Publication year - 1996
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(19961015)46:2<173::aid-jnr5>3.0.co;2-e
Subject(s) - exon , sequence (biology) , fibronectin , computational biology , characterization (materials science) , alternative splicing , biology , genetics , peptide sequence , gene , nanotechnology , cell , materials science
In order to characterize the functions of the two fibronectin type III (F3) homology domains of the neural cell adhesion molecule (NCAM), we investigated the effects of two variants, expressed as fusion proteins, of the NCAM‐F3 domains on attachment and spreading of NCAM‐expressing fibroblasts, cerebellar cell aggregation and fiber formation, and on growth cones. The two fusion proteins were different with regard to a short proline‐rich insert of six amino acids between the two F3 domains. Immobilized NCAM‐F3 fusion proteins were found to mediate attachment of both transmembrane and lipid‐anchored NCAM expressing fibroblasts. Also NCAM‐negative cells adhered to the NCAM‐F3 substratum, although to a lesser extent, implying the possibility of a heterophilic ligand to NCAM‐F3 domains on the surface of fibroblasts. Cellular spreading on NCAM‐F3 substratum was selectively increased in fibroblasts expressing transmembrane NCAM, and only the NCAM‐F3 fusion protein lacking the proline‐rich insert was able to elicit this effect. Primary cultures of mouse cerebellum were strongly inhibited with regard to formation of cellular aggregates and fibers, when incubated in the presence of either of the two NCAM‐F3 fusion proteins, the fusion protein with the proline‐rich insert being the more effective one. Finally, the morphology of growth cones from rat cerebellar granule cells changed significantly when grown on NCAM‐F3 substrata as revealed by computer‐assisted image analysis. Thus, our data indicate that the NCAM‐F3 domains are involved in cell‐cell adhesion, and that insertion of the proline‐rich sequence has a modulatory effect on NCAM‐F3 domain functions.