Early epochal maps of two different cell adhesion molecules.

Abstract

N-CAM, the neural cell-adhesion molecule, has previously been found to be expressed during several epochs of development and function, first as an early marker in embryo-genesis, later during organogenesis, and finally in adult life. L-CAM, the liver cell-adhesion molecule, has now been localized in embryonic and adult tissues of the chicken by fluorescent antibody techniques. In the early embryonic epoch, L-CAM and N-CAM appeared in epiblastic and hypoblastic tissues. L-CAM was distributed thereafter across all three germ layers. By the onset of neurulation, however, L-CAM disappeared in the region of the neural plate and N-CAM increased in amount in that region. L-CAM appeared strongly on all budding endodermal structures (liver, pancreas, lung, thyroid, parathyroid, thymus, and bursa of Fabricius) whereas N-CAM appeared most strongly in the neural plate, neural tube, and in cardiac mesoderm but was not found in endodermal derivatives. In placodes, both L-CAM and N-CAM were present until the formation of definitive neural structures, at which time L-CAM disappeared. In kidney precursors, the two CAMs followed a complex reciprocal pattern of appearance and disappearance. For the most part, however, the distributions of the two molecules did not overlap during organogenesis. Like N-CAM, L-CAM persisted in a distinctive pattern of expression in adult tissues. During embryonic development, the two different CAMs were distributed on tissues derived from more than two-thirds of the early embryonic surface. Interpretation of maps summarizing CAM distributions over a defined developmental epoch suggested a key role for both L-CAM and N-CAM in embryonic induction. Consistent with this interpretation and with the fact that the continuity of germ layers is lost when organ rudiments are formed, neither of the CAMs was limited in distribution to a single germ layer. The regions of the early epochal maps that lacked both L-CAM and N-CAM comprised some portions of the splanchnopleure and somatopleure. Certain adult tissues that derive from this lateral plate mesoderm such as smooth muscle also lacked L-CAM and N-CAM. Such observations suggest that at least one more CAM may exist in these and similarly derived tissues.

Increased C-CRK proto-oncogene expression is associated with an aggressive phenotype in lung adenocarcinomas

“…Loss of the differentiation characteristics of epithelial cells and acquisition of a more mesenchymal-like phenotype is associated with carcinoma progression (Thiery, 2002). In general, certain phenotypic alterations precipitate this transition; they include activation of several receptor tyrosine kinases, loss of E-cadherin expression, and relocalization of b-catenin (Edelman et al, 1983;Frixen et al, 1991;Miller and McClay, 1997;Morali et al, 2000;Ciruna and Rossant, 2001). Interestingly, Lamorte et al (2002) have recently demonstrated that CRKII performs a critical role in promoting an epithelial-mesenchymallike transition in epithelial cells.…”

Expression of Inappropriate Cadherins in Human Breast Carcinomas

“…However, motile cells such as fibroblasts express N-cadherin (14) and a switch from E-cadherin to N-cadherin occurs during gastrulation when epiblast cells ingress through the primitive streak to form the mesoderm (22,23). In addition, N-cadherin has been shown to correlate with a motile, fibroblastic phenotype in squamous cell carcinomas of the head and neck (11) and in melanomas (24).…”

Chromosomal location of the gene encoding the neural cell adhesion molecule (N-CAM) in the mouse.

“…The two primary CAMs are dynamically expressed in definite sequences during development (9,11) and both appear at least transiently on derivatives of all three germ layers (12). At sites of embryonic induction there are two modes of CAM expression at the cell surface: in migrating mesenchyme, N-CAM first diminishes at the cell surface and then reappears, whereas in epithelia, both N-CAM and L-CAM appear together and one or the other subsequently disappears.…”

“…These include two primary CAMs, the neural cell adhesion molecule N-CAM (3,4) and the liver cell adhesion molecule L-CAM (5,6), which are found very early in development, and one secondary CAM, the neuron-glia adhesion molecule, Ng-CAM, which appears on postmitotic neurons (7,8). Studies of these cell surface glycoproteins have suggested that there may be few primary CAMs (9) and that regulation of the expression of these molecules and of additional secondary CAMs may be pivotal processes in morphogenesis and histogenesis (10).…”