VASE exon expression alters NCAM‐mediated cell‐cell interactions

Abstract

The neural cell adhesion molecule (NCAM) is found on cells as several related polypeptides formed by alternative splicing of the single NCAM gene. The alternatively spliced 30-bp VASE exon in the fourth immunoglobulin-like domain is the structural variation nearest those portions of the polypeptide proposed to mediate cell-cell adhesion. To test the ability of distinct forms of the NCAM molecules to mediate cell adhesion, L cells were transfected with expression vectors encoding rat 140 kD NCAM +/- the VASE exon. L cell lines which expressed these polypeptides were isolated and tested for self-aggregation in a low shear, rapid aggregation assay. Increased cellular aggregation of the transfectants was observed to be a function of the NCAM molecule expressed. These transfected cells showed segregation in a long term co-aggregation assay: cells expressing NCAM--VASE formed aggregates which tended to exclude cells expressing NCAM+VASE and vice versa. These results provide direct evidence that this small difference in NCAM structure is sufficient to allow segregation of cells.

Cellular signaling by neural cell adhesion molecules of the immunoglobulin superfamily

“…The ability of neurons to extend neurites on N‐CAM‐transfected monolayers was dependent on the age of the animals from which the neurons were isolated as well as the presence of PSA on the neurons (Doherty et al, 1990a, 1991, 1992c). The ability of N‐CAM to mediate neurite extension was abolished by the presence of the VASE exon, either in the supporting cell monolayer or in the neurons (Chen et al, 1994; Doherty et al, 1992a; Lahrtz et al, 1997; Liu et al, 1993). This exon is a variable alternatively spliced exon (VASE) inserted into the fourth Ig domain of N‐CAM and it encodes a 10‐amino acid peptide (Small and Akeson, 1990).…”

Effects of taurine depletion on cell migration and NCAM expression in cultures of dissociated mouse cerebellum and N2A cells

“…However, it is yet unclear whether taurine interferes with a similar pathway in cerebellar granule neurons. In any case, the altered ratio of the VASE containing vs. VASE-negative NCAM isoforms may significantly modify both the signal transducing abilities and adhesive efficacy of NCAM (Chen et al, 1994;Doherty et al, 1996). Therefore, such a shift in the NCAM composition may well account for the taurine/GESinduced changes in the migration of granule neurons in vitro (Moran et al, 1996;Trenkner et al, 1996), although the role of the taurine-sensitive posttranslational modifications of NCAM (e.g.…”

Investigating the potential immune role of fish NCAMs: Molecular cloning and expression analysis in mandarin fish

“…For that the mRNAs of many inflammatory mediators and cytokines expressed upon inflammation contain AREs, which promote degradation [39,40], we suspect that mfNCAM1a transcript should be more stable than mfNCAM2 and mfNCAM1b, among the head kidneyoriginated members. On the other hand, the existence of VASE sequence in head kidney-originated mfNCAM1b may indicate alteration in NCAM-mediated cellecell interaction [41], since VASE was reported to inhibit NCAM-dependent adhesion [42]. Thus, in immune system, VASE-containing mfNCAM1b may be related to fewer adherences, whereas VASE-lacking mfNCAM1a may have more adhesion activity.…”