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C3d (Dendrimeric C3)
A Ligand of Neural Cell Adhesion Molecule (NCAM) promotes neuritogenesis, synaptogenesis and modulates presynaptic function
| A Synthetic Peptide Ligand of Neural Cell Adhesion Molecule (NCAM), C3d, Promotes Neuritogenesis and Synaptogenesis and Modulates Presynaptic Function in Primary Cultures of Rat Hippocampal Neurons The neural cell adhesion molecule (NCAM) plays a key role in morphogenesis of the nervous system and in remodeling of neuronal connections accompanying regenerative and cognitive processes. Recently, a new synthetic ligand of NCAM, the C3-peptide, which binds to the NCAM IgI module, has been identified by means of combinatorial chemistry [1]. In vitro, the dendrimeric form of C3, termed C3d, disrupts NCAM-mediated cell adhesion, induces neurite outgrowth and triggers intracellular signalling cascades similar to those activated by homophilic NCAM binding. The peptide may therefore be expected to regulate regeneration and synaptic plasticity. Here we demonstrate that in primary cultures of hippocampal neurons (1) C3d induces a sustained neuritogenic response, the neuritogenic activity of the compound being dependent on the dose, starting time and duration of peptide application; (2) The peptide triggers the neuritogenic response by forming an adhesive substratum necessary for NCAM-mediated neurite formation and elongation; (3) C3d promotes synapse formation; and (4) C3d modulates the presynaptic function causing a transient increase of the function at low (2 and 5 mM) doses and a reduction when applied at a higher concentration (10 mM). The effect of the peptide is dependent on the activation of the FGF receptor. We suggest that C3d may constitute a useful lead for the development of compounds for treatment of various neurodegenerative disorders. Kiryushko D., et al. J. Biol. Chem., Vol.278, Issue 14, 12325-12334, April 4, 2003 Characterization of a novel NCAM ligand with stimulatory effect on neurite outgrowth identified by screening a combinatorial peptide library The neural cell adhesion molecule, NCAM, plays a key role in neural development and plasticity mediating cell adhesion and signal transduction. By screening a combinatorial library of synthetic peptides with NCAM purified from postnatal day 10 rat brains, we identified a nonapeptide, termed NCAM binding peptide 10 (NBP10) and showed by nuclear magnetic resonance analysis that it bound the NCAM IgI module of NCAM. NBP10 modulated cell aggregation as well as neurite outgrowth induced specifically by homophilic NCAM binding. Moreover, both monomeric and multimeric forms of NBP10 stimulated neurite outgrowth from primary hippocampal neurons. The neurite outgrowth response to NBP10 was inhibited by a number of compounds previously shown to inhibit neurite outgrowth induced by homophilic NCAM binding, including voltage-dependent calcium channel antagonists, suggesting that NBP10 induced neurite outgrowth by activating a signal transduction pathway similar to that activated by NCAM itself. Moreover, an inhibitor of intracellular calcium mobilization, TMB-8, prevented NBP10-induced neurite outgrowth suggesting that NCAM-dependent neurite outgrowth also requires mobilization of calcium from intracellular calcium stores in addition to calcium influx from extracellular sources. By single-cell calcium imaging we further demonstrated that NBP10 was capable of inducing an increase in intracellular calcium in PC12E2 cells. Thus, the NBP10 peptide is a new tool for the study of molecular mechanisms underlying NCAM-dependent signal transduction and neurite outgrowth, and could prove to be a useful modulator of regenerative processes in the peripheral and central nervous system. Ronn LC, et al. Eur J Neurosci 2002 Nov;16(9):1720-30 Increased intracellular calcium is required for neurite outgrowth induced by a synthetic peptide ligand of NCAM We have recently identified a synthetic peptide, termed C3, capable of binding the first immunoglobulin-like module of neural cell adhesion molecule (NCAM) by means of combinatorial chemistry and shown that this NCAM ligand promotes neurite outgrowth. By means of single cell calcium imaging using the calcium-sensitive probe fura-2-acetomethyl ester, we here show that the C3-peptide induced an increase in intracellular calcium in primary hippocampal neurons and PC12-E2 cells, presumably requiring mobilization of calcium from both extracellular and intracellular stores. We further observed that C3-induced neurite outgrowth was inhibited by antagonists of voltage-dependent calcium channels as well as by an inhibitor of intracellular calcium mobilization, TMB-8. These findings demonstrate at the single cell level that a synthetic NCAM ligand directly can induce an increase in intracellular calcium and suggest that NCAM-dependent neurite outgrowth requires calcium mobilization from both extracellular and intracellular calcium stores. Thus, the C3-peptide may be regarded as a useful tool for the study of NCAM-dependent signal transduction. Furthermore, the peptide may be of considerable therapeutical interest for the treatment of neurodegenerative disorders. Ronn LC, et al. FEBS Lett 2002 May 8;518(1-3):60-6 |
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| P2 A NCAM responsive ligand inhibits aggregation and stimulates neurite outgrowth |
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Induction of neuronal Differentiation by a Peptide Corresponding to the Homophilic Binding Site of the Second Ig Module of the Neural Cell Adhesion Molecule NCAM plays a key role in neural development and plasticity-mediating cell adhesion and differentiation mainly through homophilic binding. Until recently, attempts to modulate neuronal differentiation and plasticity through NCAM have been impeded by the absence of small synthetic agonists mimicking homophilic interactions of NCAM. We show here that a peptide, P2, corresponding to a 12-amino acid sequence localized in the FG loop of the second Ig module of NCAM, binds to the first Ig module, which is the natural binding partner of the second Ig module, with an apparent K(d) of 4.7 0.9 x 10(-6) m. P2 inhibits cell aggregation and induces neurite outgrowth from hippocampal neurons, maximal neuritogenic effect being obtained at a concentration of 0.8 microm. The neuritogenic effect was inhibited by preincubation of P2 with the recombinant NCAM-IgI. Both the length of P2 and the basic amino acid residues at the N and C termini are important for its neuritogenic activity. Treatment of hippocampal cultures with P2 results in induction of phosphorylation of the mitogen-activated protein kinases ERK1 and ERK2. Thus, P2 is a potent mimetic of NCAM, and therefore, an attractive compound for the development of drugs for the treatment of neurodegenerative diseases. Soroka V.,et al. J Biol. Chem., Vol.277, Issue 27, 24676-24683, July 5, 2002 |
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| P2 responds to the sequence Gly172-Lys183 of NCAM, inhibits aggregation and stimulates neurite outfrowth of hippocampal neurons as well as mimics homophilic NCAM binding with respect to nodulation of cell adhesion and induction of neuronal differentiation. P2m is the monomeric form of the P2 peptide with neuritogenic effects. |
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