Differentiation‐regulated loss of the polysialylated embryonic form and expression of the different polypeptides of the neural cell adhesion molecule by cultured oligodendrocytes and myelin

Abstract

The expression of the neural cell adhesion molecule (N-CAM) on cultured murine oligodendrocytes, their precursors, and myelin was examined by indirect immunofluorescence, biosynthetic radiolabeling followed by immunoprecipitation and Western blot analysis, using antibodies specific for various forms of the molecule. In all culture systems studied, whether the oligodendrocytes were cultured as an enriched fraction containing precursor cells or in the presence of astrocytes and neurons, a similar differentiation-stage-related expression of N-CAM was seen. At early developmental stages many tetanus toxin receptor- and A2B5 antigen-positive putative oligodendrocyte precursors with bipolar morphology were seen and found to express N-CAM in its embryonic form. Of the 04 antigen-positive immature oligodendrocytes with few slender processes most expressed N-CAM, but few the embryonic form of N-CAM. The more mature 01 or 010 antigen-positive oligodendrocytes were found to express exclusively the adult form of N-CAM. Oligodendrocytes synthesized the 120 and 140 kD forms of N-CAM (N-CAM 120 and N-CAM 140), but not N-CAM 180, although with differentiation, N-CAM 120 predominated in oligodendrocytes and also in pure myelin. N-CAM 120 could be released from oligodendrocytes and myelin by phosphatidylinositol-specific phospholipase C, suggesting that in both oligodendrocytes and myelin N-CAM 120 is inserted into the membrane by covalent linkage to phosphatidylinositol.

Compartmentation of Fyn Kinase with Glycosylphosphatidylinositol-anchored Molecules in Oligodendrocytes Facilitates Kinase Activation during Myelination

“…In this paper, we investigated the association of such kinases with GPI-anchored proteins in oligodendrocytes and myelin, since they could be involved in signal transduction between the wrapping glial cell process and the axon. Our results show that the two major oligodendroglial GPI-anchored proteins, the 120-kDa isoform of NCAM (26,27) and F3 (28 -30), both members of the Ig superfamily of adhesion molecules, colocalize with the Src family kinases Fyn and Lyn in oligodendrocyte and myelin DIGs. The activity of both kinases within the DIGs is developmentally regulated, being most active at the beginning of myelination.…”

“…The following rabbit polyclonal antibodies were used: antibodies recognizing NCAM (27), F3 (Ig fraction of a serum raised against the N-terminal F3 peptide; Ref. 29), the AN2 antigen (31), Fyn, and Lyn (Santa Cruz Biotechnology, Inc., Heidelberg).…”

“…Cell Cultures and Metabolic Labeling-Primary cultures of oligodendrocytes were prepared from embryonic day 14 -16 mice as described (27,33). Oligodendrocytes growing on top of astrocyte monolayers were shaken off and plated in modified Sato medium (27) containing 1% horse serum on poly-L-lysine-coated dishes.…”

Promoting remyelination for the treatment of multiple sclerosis: opportunities and challenges

“…They are involved in many aspects of nervous system development, including axonal outgrowth and fasciculation, neuronal migration and survival, and synapse formation [54] . Polysialic acid NCAM (PSA-NCAM) is a post-translationally-modified version of NCAM existing on both oligodendrocytes and axons [55][56][57][58] . Removal of PSA from axons [59] and oligodendrocytes [60] is a prerequisite for the initiation of myelination during development.…”

Autocrine/Paracrine Activation of the GABAAReceptor Inhibits the Proliferation of Neurogenic Polysialylated Neural Cell Adhesion Molecule-Positive (PSA-NCAM+) Precursor Cells from Postnatal Striatum

“…Although they are already restricted to either a glial (Trotter et al, 1989;Grinspan and Franceschini, 1995;Ben Hur et al, 1998;Vitry et al, 1999) or a neuronal (Mayer-Proschel et al, 1997) preferential fate, cultured PSA-NCAM ϩ progenitors preserve a relative degree of pluripotentiality (Marmur et al, 1998;Vitry et al, 2001). Considering that PSA-NCAM ϩ cells can be neatly used for brain repair purposes (Keirstead et al, 1999;Vitry et al, 2001), there is much interest in studying signaling factors that regulate their development.…”