Characterization of Soluble Neural Cell Adhesion Molecule in Rat Brain, CSF, and Plasma

Abstract

The polypeptide composition and glycosylation of soluble isoforms of neural cell adhesion molecule (NCAM) in developing rat brain, CSF, and plasma were characterized. Soluble NCAM in rat brain consisted of several glycosylated isoforms. The degree of glycosylation was developmentally regulated. After desialylation, four polypeptides of M(r) values of approximately 190,000 (s1), 135,000 (s2), 115,000 (s3), and 110,000 (s4) were observed. Polypeptides s1, s2, and s3 were also present in CSF, whereas only s3 and s4 were observed in plasma. Treatment of soluble brain NCAM with N-glycosidase F, which removes N-linked carbohydrates, produced polypeptides of M(r) values of approximately 190,000, 125,000, and 108,000-97,000. The monoclonal antibody OB11, which recognizes an epitope on the cytoplasmic part of transmembrane forms of NCAM, did not react with any of the soluble isoforms. Purified soluble NCAM, consisting mainly of s3, contained an N-terminal sequence identical to that of membrane-associated NCAM. Gel filtration of s3 indicated that it was present as a dimer under the chosen conditions. NCAM-expressing glioma cells adhered specifically to immobilized soluble NCAM. This implies that functionally significant soluble forms of NCAM are present in the extracellular fluid.

Cholinergic agonists stimulate secretion of soluble full-length amyloid precursor protein in neuroendocrine cells.

“…In contrast, we were able to detect solAPPcyt in human cerebrospinal fluid (CSF) without prior binding to heparin (Fig. 5B) (30), showed that functional forms of the neural cell adhesion molecule (N-CAM) with intact transmembrane sequence, are present in CSF and plasma (31). Similarly, a form of the insulin receptor, a type I transmembrane protein, was secreted with its transmembrane sequence from cultured cells and was also detected in human plasma (32).…”

Metalloprotease‐induced ectodomain shedding of neural cell adhesion molecule (NCAM)

“…Moreover, a %115 kD band representing the soluble NCAM140 ectodomain appeared on blots of the conditioned media from pervanadate-stimulated cells using -NCAM-ECD antibodies ( Fig. 1, PV lower panel), and is the reported size of the NCAM ectodomain (Bock et al, 1987;Nybroe et al, 1989;Krog et al, 1992;Todaro et al, 2004). The 115 kD NCAM fragment was not present in conditioned media from untreated or PMA-treated cells.…”

“…3, PV þ MCD), while MCD alone did not induce shedding. The levels of the 30 kD cytoplasmic tail were slightly reduced in MCD/pervanadate-treated cells as compared to pervanadate-only treated cells, but a small amount of an additional cleaved NCAM fragment of %37 kD in the lysate and an increase of a media fragment of %118-120 kD were present, which could represent an additional cleavage site (Krog et al, 1992;Vawter et al, 1998bVawter et al, ,c, 2000b. These fragments also may account for the lack of increase in the 30 kD form.…”

Expression and alternative splicing of the neural cell adhesion molecule NCAM in human granulosa cells during luteinization

“…Thus the alternatively spliced exon VASE in the fourth Ig domain, which is physically close enough to the regions of the molecule thought to mediate cell--cell interaction, may modulate interaction of granulosa cells. In addition, soluble NCAM forms observed in different body fluids [37], pos-…”