A classic way to disrupt cell adhesion phenomena is to add a soluble ligand that

Question

A classic way to disrupt cell adhesion phenomena is to add a soluble ligand that blocks the receptor on the cell surface. This is shown schematically below. Figure 3 Cartoon representing how a soluble ligand can block cell adhesion. A soluble ligand that binds to the alpha 4 beta 1 integrin was introduced into the head region of chick embryos just after neurulation. The embryos developed with severely deformed facial skeleton, up to and including a complete lack of facial and jaw bones. Why would this have happened?

Explanation / Answer

Cell migration is essential for proper development of numerous structures derived from embryonic neural crest cells (NCCs). The neural crest is a transient embryonic cell population which migrates long distances through the vertebrate embryo during development and gives rise to diverse derivatives.Integrins are heterodimeric transmembrane receptors that bind both ECM and cytoskeletal proteins, and thus provide a transmembrane link between extracellular signals and intracellular mechanical forces.Efficient cell motility requires an intermediate level of cell adhesion because cells that are too weakly attached cannot generate enough traction for movement

The adhesion and migration of NCCs, are primarily mediated by beta 1 integrins, whose ligands include two major ECM molecules, laminin and fibronectin ,Both laminin and fibronectin are abundantly expressed in neural crest migration pathways .

Two subpopulations of neural crest, cranial and trunk (based on their axial level of origin), differ in their requirement of divalent cations for attachment to laminin and fibronectin, suggesting that differences in integrin activation levels may underlie distinctions between embryonic cell populations

Integrins have structural roles in adhesion that promote tissue integrity and cell migration, and signaling functions important for cell differentiation and survival . Integrins 4B1, have role in neural crest development

the first pharyngeal pouch fails to develop, and the lack of a first pouch correlates with reductions in specific regions of the HS cartilage. integrin mutants also have defects in a subset of dorsal first and second arch muscles and facial motor nerve VII, suggesting that Integrin is required for region-specific development of multiple pharyngeal tissues

The neural crest cells migrate extensively to generate a prodigious number of differentiated cell types. These cell types include (1) the neurons and glial cells of the sensory, sympathetic, and parasympathetic nervous systems, (2) the epinephrine-producing (medulla) cells of the adrenal gland, (3) the pigment-containing cells of the epidermis, and (4) many of the skeletal and connective tissue components of the head.

so after adding the soluble ligand that binds to 4B1 affect neural crest cell that migrate extensively to generate a prodigious number of differentiated cell types

integrins 4B1 has important role in cell survival in developing ratina-mportant in many phases of neuronal development, particularly neuroblast migration and axon outgrowth in the retina

Central role of the alpha4beta1 integrin in the coordination of avian truncal neural ... a critical role during neural crest cell migration in the embryo because integrin has role in cell adhesion, migration, survival, proliferation, and differentiation

inhibition of alpha4beta1 activity in vitro resulted in a strong, immediate and sustained reduction of neural crest cell motion on fibronectin

it give rise to increased apoptosis and led to a thinning of the retina and reduced numbers of retinal ganglion cells

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