Protein-mediated cell adhesion

Cell adhesion, protein-mediated, on biomaterials, 143-145 Ceramics... 

Additional Cell Adhesion Proteins Are Required to Mediate the Immune Response Immune Recognition Molecules Are Evolutionarily Related... 

Cell adhesion on a nonfunctional scaffold is mediated dominantly by nonspecific, entropically favored adsorption of a layer of cell adhesion proteins, excreted by the cell itself [61]. In order to obtain and retain the native function of these proteins, attempts are being made to tune the hydrophilicity or hydrophobicity of the scaffold surfaces [62], Different methods of surface activation are commonly applied, e.g., blending, copolymerization, plasma treatment, etching, radiation, chemical surface modification, coatings, and combinations of those. 

Fibronectin and related cell adhesion proteins have been shown to mediate the attachment of many mammalian cells to natural and artificial substrata. Following a presentation of our current understanding of the molecular biology of cell adhesion, factors influencing the attachment and growth of cells on polymeric substrata are discussed. 

In addition to gangliosides, heparin related molecules have also been shown to be involved in fibronectin mediated cell adhesion. Heparin binding sites have been described on many cell adhesion proteins e.g., fibronectin (25-26), laminin (27), and vitronectin... 

Whether on natural or synthetic materials, cell adhesion is mediated by protein interactions with cell surface receptors. There are several classes of cell surface receptors, and this chapter will discuss integrins, selectins, and immunoglobulins. These receptors bind their ligands with high affinity and specificity, and while each receptor family regulates separate cellular functions, there is some overlap between families. Each of these receptor families possesses a characteristic molecular structure, with every receptor... 

However, the mechanisms behind nanotopographically mediated tissue responses are still not clear. The increased adsorption of cell adhesive proteins (such as fibronec-tin, vitronectin, etc.) on nanoscale rough surfaces, due to either uneven surface landscapes or inaeased specific surface area, is a plausible mechanism. However, this mechanism is not enough to explain aU the nanoscale roughness (or nanotopography) related tissue responses. For example, there is a lack of evidence to explain the fact the many different types of cells see the same roughness but their responses are different from cell type to cell type [64]. These questions will be further examined in Chapter 8. 

The classical cadherins are translated as precursor because they are N-terminally cleaved to reveal the mature proteins. This processing is required to activate the cell adhesion function of cadherins. Cadherins interact in trans (i.e., from opposite cells) via the most N-terminal cadherin rqDeats. A short amino acid sequence within this repeat, histidine-alanine-valine (HAV), has been implicated in mediating cell-cell contacts as HAV peptides can disrupt cadherin-dependent cell adhesion. Besides the trans-interactions of cadherins, the extracellular domains are also capable of forming cis-dimers through lateral amino acid contacts between cadherin molecules on one cell. This dimerization again mainly involves the first cadherin repeat. A zipper model based on the pattern of alternating cis- and trans-dimers [1] for the adhesive interactions has been proposed. 

Figure 2. (1) Neutrophils circulating passively in blood capillary. (2) Chemoattractants may be detected by the circulating neutrophils, by the endothelial cells lining the lumen, or both in order that the neutrophils become adhesive. This adhesion is mediated by selectins, a group of cell surface proteins. Neutrophils roll on the surface of the endothelial cells and then actively locomote seeking out spaces between the endothelial cells. (3) The adhesive neutrophils begin to squeeze between endothelial cells. (4) Cells move through the extracellular matrix towards the site of infection. Here adhesion is low and may not be necessary for locomotion. (5) At the site of infection, neutrophils become trapped by increased adhesion where they phagocytose bacteria and liberate the contents of their granules. After Lackie (1982,1986).

Jung H, Toth PT, White PA, Miller RJ (2008) Monocyte chemoattractant protein-1 functions as a neuromodulator in dorsal root ganglia neurons. J Neurochem 104 254-263 Kahn L, Alonso G, Normand E, Manzoni OJ (2005) Repeated morphine treatment alters polysia-lylated neural cell adhesion molecule, glutamate decarboxylase-67 expression and ceU proliferation in the adult rat hippocampus. Em J Nemosci 21 493-500 Kaul M, Ma Q, Medders KE, Desai MK, Lipton SA (2007) HIV-1 coreceptors CCR5 and CXCR4 both mediate neuronal cell death but CCR5 paradoxically can also contribute to protection. Cell Death Differ (2) 296-305... 

Haskell CA, Cleary MD, Charo IF. Molecular uncoupling of fractalkine-mediated cell adhesion and signal transduction. Rapid flow arrest of CX3CR1-expressing cells is independent of G-protein activation. J Biol Chem 1999 274(15) 10053-10058. 

Chemokines, a superfamily of small (8 to 14 kd) chemoattractant cytokines, were originally identified by their capacity to mediate gradient-dependent cell migration, accompanied by Ca2+ flux, in vitro. Sequence homology of mammal, bird, and fish chemokines indicates that this family of proteins is highly conserved throughout evolution. Chemokines are multifunctional molecules with a vast repertoire of specialized functions in different organs. Broadly, chemokine actions are associated with cell adhesion, cytokine secretion, cellular... 

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