J. R. Coll. Surg. Edinb.,
, August, 223—229
The role of cell adhesion molecules in craniofacial development
J. J. KERRIGAN, J. T. McGILL, J. A. DAVIES, L. ANDREWS AND I. R. SANDY
Division of Child Dental Health, Department of Oral and Dental Sciences, University of Bristol, UK
The last decade has seen classification and characterization of previously identified glycoproteins
which have been associated with cell adhesion. More recently, it has been realized that the range of
these molecules is even wider than originally thought. Cell adhesion molecules are important in
early development and their role in craniofacial development is now apparent. Furthermore, the
interaction of cell adhesion molecules in other developmental phenomena such as epithelial
mesenchymal transformation (EMT), reinforces the suggestion that these molecules are important
in the later stages of development, particularly organogenesis. This article reviews the role of cell
adhesion molecules in embryogenesis, with a particular emphasis on foetal craniofacial
Keywords: cell adhesion molecules, craniofacial development, review.
The first suggestion that cell adhesion molecules exist came from Moscona in 1952 who noted that in
experiments with developing chick embryos the cells of completely disrupted tissues could reassemble and
reform the original tissue structure. It was suggested that the ability of cells to re-aggregate was due to the
presence of adhesion molecules present within the cell membrane.
Since the pioneering work of
Moscona, Townes and Holtfreter in the 1950s, significant steps have been made in the identification,
characterization and classification of several distinct cell adhesion systems in developing embryos.
These systems allow cells to interact dynamically with adjacent cells and the extra-cellular matrix. They
are of importance in the development, morphogenesis, maintenance and regeneration of the form,
structure and organization of organisms.
In addition, they appear to have a role to play in an organism’s
ability to resist tumour invasion and metastasis.
The functional units of cell adhesion systems are multiprotein complexes. Three classes exist:
adhesion molecules (CAMs); (ii) extra-cellular matrix proteins; (iii) cytoplasmic linking proteins. These
are illustrated diagrammatically in Figure 1.
The diagram schematically
illustrates the functional units of the cell
adhesion system. This demonstrates how
the components of the cytoskeleton are
linked via the cytoplasmic plaques and
transmembrane glycoproteins to the
extra-cellular matrix (ECM). Many of the
ECM proteins which are responsible for
cell adhesion contain common peptide
sequences as cell recognition sites. These
are recognized by integrins or cadherins
which span the cell membrane from the
extra-cellular matrix to the cytoplasm.
These transmembrane proteins do not