Mechanisms of adhesion among cells from neural tissues of the chick embryo.

Abstract

In order to analyze the molecular mechanisms of cell adhesion during development, proteins on the surface of chick embryonic neural cells were compared with proteins released after placing these cells in culture. One of the components released into culture, F1 (molecular weight, M, 140,000), was derived by proteolytic cleavage of a cell surface precursor with a molecular weight of at least 240,000.Another proteinj F2, recovered Cell adhesion has attracted the attention of biologists in a variety of fields because it reflects some of the most fundamental aspects of metazoan physiology. Several attempts have been made to analyze cell adhesion, but as yet its physical basis remains unknown. The main conclusion that can be drawn from these studies (1-5) is that adhesion is a complex phenomenon that in some way includes molecular ligation of cell surfaces. In view of this complexity, an experimental approach requires an analysis of (a) the structure of molecules expressed at and released from the cell surface; (b) the specific interactions among these molecules; (c) the relationship of the properties of these molecules to cell-cell binding in kinetically defined assays; and (d) the relationship of this binding to tissue formation.In this paper, we describe the application of this approach to the study of adhesion among dissociated retinal and brain cells from chick embryos. These studies suggest that proteolytic alteration of a major cell surface protein results in the appearance of determinants required for the initial formation of bonds between both retinal and brain cells. A model of the activation and ligation steps has been formulated and the overall control of adhesion during the development of these two tissues is discussed in terms of this model. Isolation of Proteins F1 and F2 from Retina. Retinas from 10-day embryos were cultured either as intact tissue in medium with Trasylol, or as cell monolayers in medium with 5% serum. Supernatants from cultures of intact tissue (TCS) were collected after 24 hr and centrifuged to remove debris. Cells in monolayer cultures were washed and incubated for 24-48 hr in medium without serum but with Trasylol, after which the monolayer culture supernatant (MCS) was collected and centrifuged. MATERIALS AND METHODSAfter a 30-fold concentration by ultrafiltration through Amicon PM-10 membranes, MCS and TCS from 400 retinas were passed through DE-52 DEAE-cellulose (Whatman) columns in 0.01 M Tris-HCl-0.4 M KCl, pH 7.2, to remove nucleic acids, and fractionated on a 0.5 X 10 cm column of DE-52 in 0.01 M Tris, pH 7.2, with a linear gradient from 0.01 to 0.4 M KCl. Fractions containing the F1 or F2 proteins (see Fig. 1) were identified by analytical polyacrylamide gel electrophoresis, pooled, and further separated by preparative gel electrophoresis on 1 cm X 10 cm cylindrical gels of 6.5% acrylamide in Tris-glycine buffer (6). F1 and F2 were located by scanning the gels at 280 nm with a Gilford spectrophotometer and eluted from the appropriate gel slice by electrophoresis (...

Isolation of the intercellular glycoproteins of desmosomes.

“…Many workers have associated cell surface glycoproteins with adhesion-related activities in systems such as sponges (9), slime molds (19,27), and avian and mammalian cells (7,28,36). Our fording that the function of an adhesive organelle, the desmosome, may be mediated by certain glycoproteins is also supported by ultrastructural localization of carbohydrate in the intercellular region of desmosomes, using various histochemical stains such as ruthenium red (11), phosphotungstic acid (8), and periodic acid-silver methenamine (8,22).…”

Characterization of the kinetics of neural cell adhesion molecule homophilic binding

“…Abbreviations: P0 NCAM, neural cell adhesion molecule isolated from newborn rat brains; P40 NCAM, NCAM isolated from rat brains at postnatal day 40; PBS, phosphate-buffered saline; PSA, polysialic acid NCAM-mediated adhesion appears to occur by a homophilic and possibly polyvalent binding mechanism [1, 11,12] in which NCAM on the surface of one cell binds to NCAM on an opposing cell. Studies by Cole and Glaser [10] have demonstrated that cell surface NCAM also participates in cell-substratum interactions in the developing chick nervous system.…”

A novel role for neural cell adhesion molecule in modulating insulin signaling and adipocyte differentiation of mouse mesenchymal stem cells

“…The neural cell adhesion molecule (NCAM), also known as CD56, belongs to the immunoglobulin superfamily (Jorgensen and Bock, 1974;Rutishauser et al, 1976). Widely expressed on neural cells of the central and peripheral nervous system (Schmid et al, 1999), NCAM has been implicated in neurite outgrowth, cell-cell adhesion, synaptic plasticity, learning and memory (Angata et al, 2004;Eckhardt et al, 2000;Weinhold et al, 2005).…”