Differential expression of mouse neural cell-adhesion molecule (N-CAM) mRNA species during brain development and in neural cell lines

Abstract

The cell-adhesion molecules N-CAM (neural cell-adhesion molecule) are ligands in the formation of cell-cell bonds and have been shown to play important roles during neuro-ontogenesis. They exist in several molecular forms which differ at the protein and carbohydrate levels. The regulation of the expression of these different forms is an important issue that bears on such questions as to how adhesive interactions between cells are modulated during morphogenesis. In the present study we have used N-CAM cDNA clones to investigate the expression of the cognate mRNAs in the mouse and rat brain and in 2 neural cell lines. The results were compared with the levels of the different N-CAM proteins. We made the following observations. A complex set of 5 size classes of mRNAs--which show developmental, regional, and cell-type-dependent variations in their expression--hybridize to 1 of our cDNA probes. While embryonic brain contains N-CAM gene transcripts 7.4, 6.7, and 4.3 kilobases (kb) in length, 2 additional mRNAs of 5.2 and 2.9 kb appear postnatally. Transformed brain cells of an astrocytic character express predominantly mRNAs of 6.7, 4.3, and 2.9 kb and a neuroblastoma line those of 7.4, 6.7, 4.3, and 2.9 kb. There are important quantitative changes in the amount of N-CAM message expressed during brain development, with a peak around birth, suggesting that N-CAM synthesis is controlled at the transcriptional level. A comparison of N-CAM protein and mRNA levels reveals a striking correlation between the relative concentrations of the Mr 120,000 N-CAM protein (N-CAM120) and the 5.2 kb transcript.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of rat brain NCAM mRNA using DNA oligonucleotide probes

“…It did not recognize any mRNAs in adult rat liver which was run concomitantly in all experiments. When hybridizing the E7 probe to brain mRNA isolated from different stages of development, the same developmental changes in NCAM mRNAs as described in [6,19] were seen (data not shown). The 4.3 kb mRNA class was only present in small amounts and usually observed in rat brain postnatal days 4 and 10, where the total NCAM mRNA amount was highest.…”

The mouse neuronal cell surface protein F3: a phosphatidylinositol-anchored member of the immunoglobulin superfamily related to chicken contactin.

“…The RNA preparations were fractionated by electrophoresis on 1% agarose gels containing formaldehyde and blotted to nitrocellulose (Thomas, 1980). Prehybridization and hybridization conditions were as described (Gennarini et al, 1986). Probes were labeled by random priming (Feinberg and Vogelstein, 1984) and used at 2 × 106 cpm/ml.…”

“…Proteins were separated on 6.67% SDS-polyacrylamide gels and blotted onto nitrocellulose as previously described (Gennarini et al, 1986). Molecular weight markers, with their apparent relative molecular masses given in parentheses, were myosin (220,000), beta-galactosidase (120,000), phosphorylase b (94,000), BSA (68,000), ovalbumin (43,000), and carbonic anhydrase (30,000).…”

Transcription initiation sites and structural organization of the extreme 5' region of the rat neural cell adhesion molecule gene.

“…The difference in the overall intensity of the bands may be due to the different NCAM mRNA abundance in the samples. For example, the overall intensity of the bands in the adult brain lane is lower than that of postnatal day 7 brain, reflecting the lower NCAM mRNA abundance in adult brain (22 Dot blot analysis (Fig. 9) demonstrates that the levels of the NCAM mRNAs encoding 120-kDa and 180-kDa isoforms are different in different cell types and developmental stages.…”

“…NCAM-120 lacks a transmembrane domain (47) and is bound to the membrane by a phosphoinositide linkage (29)(30)(31). NCAM appears to be encoded by a single gene (15,46,48), but at least four to five mRNA major size classes were found in all species examined to date: mouse (22,25), rat (58), chicken (14,45), Xenopus laevis (38), and human (16). In rat, these mRNAs are 7.4, 6.7, 5.2, 4.3, and 2.9 kilobases (kb) long (58).…”