Neuronal cell adhesion

The cytoskeleton is found near the axonal membrane and consists of microfilaments linked internally to microtubules and the plasma membrane by a network of filamentous protein that includes the brain-specific protein fodrin. This protein forms attachment sites for integral membrane proteins either by means of the neuronal cell adhesion molecule (N-CAM) or indirectly by means of a specific protein called ankyrin in the case of the sodium channels. This may provide a means whereby the sodium channels are concentrated in the region of the nodes of Ranvier. Thus the cortical cytoskeleton plays a vital role in neuronal function by acting as an attachment site for various receptors and ion channels, but also for s)maptic vesicles at nerve terminals, thereby providing a mechanism for concentrating the vesicles prior to the release of the neurotransmitter. 

The receptor-like protein tyrosine phosphatases have a transmembrane and, in some cases, a large extracellular domain with a very variable structme (Fig. 8.16). Many, but not all, membrane protein tyrosine phosphatases have two catalytic domains in the cytoplasmic region. The complete structme is very similar to the structure of transmembrane receptors. Understanding of their function is far from complete. Both the natural ligands and the substrate proteins following in the sequence are incompletely characterized. Several studies have demonstrated a role for receptor-like PTPs in neuronal cell adhesion signaling pathways. In cells of the neural tissue, a surface protein, contactin has been identified as ligand for the extracellular domain of a protein tyrosine phosphatase (Peles et al., 1995). 

Ueoka, C., Kaneda, N., Okazaki, I., Nadanaka, S., Muramatsu, T., and Sugahara, K. (2000). Neuronal cell adhesion, mediated by the heparin-binding neuroregulatory factor midkine, is specifically inhibited by chondroitin sulfate E. J. Biol. Chem. 275,37407-37413. 

PSA-NCAM, polysialic acid-neuronal cell adhesion molecule... 

NCAM, neuronal cell adhesion molecules (such as H-CAM, G-CAM, VCAM-1)... 

Simpson CS, Morris. BJ (2000) Regulation of neuronal cell adhesion molecule expression by NF-kappa B. J Biol Chem 275 16879-16884... 

Adhesion molecules. The downregulation of the polysialylated neuronal cell adhesion molecule (PSA-NCAM) from the axonal surface (Charles et al 2000) is a necessary prerequisite to render the axon permissive to myelination (Charles et al., 2002 Coman et al., 2005). LI, another adhesion molecule expressed at the axonal surface, promotes myelination (Coman et al., 2005). 

Hirao K, Hata Y, Ide N, Takeuchi M, Irie M, et al. 1998. A novel multiple PDZ domain-containing molecule interacting with N-methyl-D-aspartate receptors and neuronal cell adhesion proteins. J. Biol. Chem. 273 21105-10... 

Durbec P, Gennarini G, Goridis C, Rougon G. 1992. A soluble form of the F3 neuronal cell adhesion molecule promotes neurite outgrowth. J Gell Biol 117 877-887. 

In reproductive biology, sialic acid polymers are receiving more and more attention. Polysialic acid with a(2-8)-linkages was found to be expressed on mouse embryos before and after implantation and the neuronal cell adhesion molecule (NCAM), which bears a polysialic acid chain, seems to be involved in cellular interactions in the early mammalian embryo [101,1076]. A similar function is attributed to polysialic acid observed during a short period of the larval stage of Drosophila melanogaster [1077]. It has to be noted that this is the first report on the occurrence of sialic acid in insects. 

Cell membrane-associated proteins such as neuronal cell adhesion molecule (NCAM, CD56) and leu-7 (CD57) have raised interest as neuroendocrine cell... 

The mode of anchoring of Thy-1 to the cell membrane is unusual in that it occurs via a phosphoinositide rather than via a hydrophobic amino acid stretch within the protein itself [188.189], An identical mode of membrane anchoring has been reported for a form of the neuronal cell-adhesion molecule (see below) as well as for a T cell activating protein (TAP, [190]), which is also expressed on the majority of mouse T cells and, whilst having a similar molecular weight, is clearly distinct from Thy-1. 

Hartwig C, et al. Elevated phenylalanine levels interfere with neurite outgrowth stimulated by the neuronal cell adhesion molecule LI in vitro. FEBS Lett. 2006 580(14) 3489-92. 

Conversely, a new line of inquiry examined glutamatergic activity, not as a blocker of neurotransmission but as an agonist of AMPA type receptors. A new class of compounds, called ampakines, act as long-term boosters of the learning process, Aniracetam [206] is considered as the major product in this series. It improves performance in all classical behavioural tests in animal models. The question which has to be answered is whether these compounds simply have symptomatic effects on memory processes or whether they have complementary properties such as inhibition of cell death [207], Furthermore, certain compounds currently classed as ampakines such as oxiracetam and piracetam have not been shown to be effective in Alzheimer s disease. Others, such as nefiracetam (12) are in the animal experimentation stage and appear to be promising because of their impact on the neuronal cell adhesion molecules (NCAM) [208] and their effect on synapse plasticity. 

Harsch A, Calderon J, Timmons RB, Gross GW. Pulsed plasma deposition of allyl-amine on polysiloxane a stable surface for neuronal cell adhesion. J Neurosci Methods 2000 98 135-44. 

Increased osteoblast adhesion, proliferation, mineralization, and protein marker expression Increased elastic modulus, neuronal cell adhesion, neurite extension, and decreased astrocyte adhesion Supports the aggregation and enhances the migration abihty of endothelial cells... 

Neural tissue Increased elastic modulus, neuronal cell adhesion, engineering neurite extension, and decreased astrocyte adhesion... 

The HA hydrogel can be chemically modified in many different ways in order to achieve a better ECM-like component and architecture, to promote its interaction with cells. PLL is usually used as a coating substrate on the surface for cell adhesion when being cultured in vitro. It can be taken into the gel for the modulation of neuronal cell adhesion and neural network formation. The report by Tian and co-workers [20] has shown that this modified hydrogel has good compatibility with the cells and surrounding tissue in the brain. 

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