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  • 1
    Electronic Resource
    Electronic Resource
    The F3 Neuronal Glycosylphosphatidylinositol-Linked Molecule Is Localized to Glycolipid-Enriched Membrane Subdomains and Interacts with L1 and Fyn Kinase in Cerebellum (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 65 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The F3 molecule is a member of the immunoglobulin superfamily anchored to plasma membranes by a glycosylphosphatidylinositol group. In adult mouse cerebellum, F3 is predominantly expressed on a subset of axons, the parallel fibers, and at their synapses. In vitro studies established that it is a plurifunctional molecule that, depending on the cellular context and the ligand with which it interacts, either mediates repulsive interactions or promotes neurite outgrowth. In the present study, we report the isolation of two fractions of F3-containing microdomains from adult cerebellum on the basis of their resistance to solubilization by Triton X-100 at 4°C. Both fractions were composed of vesicles, ranging from 100 to 200 nm in diameter. Lipid composition analysis indicated that the lighter fraction was enriched in cerebrosides and sulfatides. F3 sensitivity to phosphatidylinositol phospholipase C differed between the two fractions, possibly reflecting structural differences in the lipid anchor of the F3 molecule. Both fractions were highly enriched in other glycosylphosphatidylinositol-anchored proteins such as NCAM 120 and Thy-1. It is interesting that these vesicles were devoid of the transmembrane forms (NCAM 180 and NCAM 140), which were recovered in Triton X-100-soluble fractions, but contained the L1 transmembrane adhesion molecule that is coexpressed with F3 on parallel fibers and the fyn tyrosine kinase. Immunoprecipitation experiments indicated that F3, but not NCAM 120 or Thy-1, was physically associated in a complex with both L1 and fyn tyrosine kinase. This strongly suggests that the interaction between L1 and F3, already described to occur with isolated molecules, is present in neural tissue. More important is that our study provides information on the molecular machinery likely to be involved in F3 signaling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.65052307.x
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  • 2
    Electronic Resource
    Electronic Resource
    Protein Phosphorylation Induced by Phorbol Esters and Cyclic AMP in Anterior Pituitary Cells: Possible Role in Adrenocorticotropin Release and Synthesis (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 52 (1989), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Forskolin, an activator of adenylate cyclase, stimulates adrenocorticotropin (ACTH) release and increases proopiomelanocortin mRNA levels in anterior pituitary cells by enhancing cyclic AMP (cAMP)-dependent protein kinase activity. The phorbol ester phorbol 12-myristate 13-acetate (PMA) evokes these same responses from anterior pituitary cells by activating protein kinase C. Both protein kinases most likely induce their cellular effects by catalyzing the phosphorylation of specific proteins. To elucidate the mechanisms by which cAMP-dependent protein kinase and protein kinase C promote ACTH secretion and synthesis, the phosphoproteins regulated by forskolin and PMA were identified in the cell line AtT-20, which consists of a homogeneous population of corticotrophs. Phosphoproteins were analyzed in different subcellular fractions by two-dimensional polyacrylamide gel electrophoresis and autoradiography. Forskolin increased phosphate incorporation into two proteins in the cytoplasmic fraction of 24 kilodaltons (kd) (pi 6.8) and 40 kd (pi 5.8), two proteins in the plasma membrane fraction of 32 kd (pi 8.3) and 60 kd (pi 8), and one protein in the nuclear fraction of 20 kd (pI 8.7). Insertion of the inhibitor of cAMP-dependent protein kinase into the AtT-20 cells, using a liposome technique, blocked the rise in phosphate incorporation induced by forskolin. PMA also stimulated phosphate incorporation into proteins in AtT-20 cells. PMA increased the phosphorylation of three cytoplasmic proteins of 25 kd (pi 7.6), 40 kd (pi 5.8), and 40 kd (pI 8.1) as well as two membrane proteins of 32 kd (pi 8.3) and 60 kd (pi 8) and one nuclear protein of 20 kd (pi 6.3). The inhibitor of cAMP-dependent protein kinase did not reduce the protein phosphorylation induced by PMA. The possible role of protein phosphorylation in the stimulation of ACTH release and synthesis by cAMP-dependent protein kinase and protein kinase C is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1989.tb01875.x
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  • 3
    Electronic Resource
    Electronic Resource
    Removal of C6 Astrocytoma Cell Surface Molecules with Phosphatidylinositol Phospholipase C: Effect on Regulation of Neurol Cell Adhesion Molecule Isoforms (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Different membrane-associated isoforms of the Neurol cell adhesion molecules have been described. One of them, N-CAM120, has been shown to be anchored to the membranes by a complex glycan-phosphatidylinositol group and to be releasabie, under soluble form, by the bacterial enzyme phosphatidylinositol-phospholipase C. We used the C6 rat astrocytoma cell line expressing both N-CAM120 and the transmembrane isoform N-CAM 140 as a model system. We investigated whether artificial depletion of cell membrane N-CAM 120 influences the synthesis and the messenger RNA transcript levels of the isoforms of the Neurol cell adhesion molecules. Our results showed an increase in the rate of N-CAM120 protein synthesis, whereas the expression of N-CAM140 decreased. Additionally, perturbations in the levels of the 6.7-kb messenger RNA encoding for N-CAM 140 were observed, whereas the 2.7-kb transcript encoding for N-CAM120 remained stable. Examination of the time course for the reexpression of N-CAM 120 showed that control levels were recovered after 24 h. We provide evidence that: N-CAM 120 spontaneously released in the culture medium is not incorporated into the extracellular matrix; however, its concentration is important because, if the medium was changed, cells rapidly released a new pool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb02100.x
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  • 4
    Electronic Resource
    Electronic Resource
    Soluble forms of NCAM and F3 neuronal cell adhesion molecules promote Schwann cell migration: identification of protein tyrosine phosphatases ζ/β as the putative F3 receptors on Schwann cells (2001)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 78 (2001), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neural cell adhesion molecule (NCAM) and F3 are both axonal adhesion molecules which display homophilic (NCAM) or heterophilic (NCAM, F3) binding activities and participate in bidirectional exchange of information between neurones and glial cells. Engineered Fc chimeric molecules are fusion proteins that contain the extracellular part of NCAM or F3 and the Fc region of human IgG1. Here, we investigated the effect of NCAM-Fc and F3-Fc chimeras on Schwann cell (SC) migration. Binding sites were identified at the surface of cultured SCs by chimera coated fluorospheres. The functional effect of NCAM-Fc and F3-Fc binding was studied in two different SC migration models. In the first, migration is monitored at specific time intervals inside a 1-mm gap produced in a monolayer culture of SCs. In the second, SCs from a dorsal root ganglion explant migrate on a sciatic nerve cryosection. In both systems addition of the chimeras significantly increased the extent of SC migration and this effect could be prevented by the corresponding anti-NCAM or anti-F3 blocking antibodies. Furthermore, antiproteoglycan-type protein tyrosine phosphatase ζ/β (RPTPζ/β) antibodies identified the presence of RPTPζ/β on SCs and prevented the enhancing effect of soluble F3 on SC motility by 95%. The F3-Fc coated Sepharose beads precipitated RPTPζ/β from SC lysates. Altogether these data point to RPTPζ/β is the putative F3 receptor on SCs. These results identify F3 and NCAM receptors on SC as potential mediators of signalling occurring between axons and glial cells during peripheral nerve development and regeneration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2001.00454.x
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  • 5
    Electronic Resource
    Electronic Resource
    NEW INSIGHTS INTO THE DIVERSITY AND FUNCTION OF NEURONAL IMMUNOGLOBULIN SUPERFAMILY MOLECULES (2003)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 26 (2003), S. 207-238 
    Details
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Immunoglobulin superfamily (IgSF) proteins are implicated in diverse steps of brain development, including neuronal migration, axon pathfinding, target recognition and synapse formation, as well as in the maintenance and function of neuronal networks in the adult. We provide here a review of recent findings on the diversity and the role of transmembrane and secreted members of IgSF proteins in the nervous system. We illustrate that the complexity of IgSF protein function results from various different levels of regulation including regulation of gene expression, protein localization, and protein interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.neuro.26.041002.131014
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  • 6
    Electronic Resource
    Electronic Resource
    Polysialylated Neural Cell Adhesion is Involved in Target-induced Morphological Differentiation of Arcuate Dopaminergic Neurons (1997)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 9 (1997), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have previously shown that the morphological and biochemical maturation of developing rat hypothalamic dopaminergic neurons is accelerated when they are cocultivated with pituitary intermediate lobe cells, one of their targets. Only two subsets of hypothalamic dopaminergic neurons (arcuate, A12, and periventricular, A14, nuclei) may project to the pars intermedia. In order to determine whether the two populations are equally responsive to coculture conditions, we microdissected the hypothalamus of 17-day-old rat fetuses in two fragments containing cell bodies from the A12 and from the A14 regions, prepared neuronal cultures from both portions and incubated them separately with intermediate lobe cells. The presence of intermediate lobe cells increased tyrosine hydroxylase levels in both dopaminergic neuron subsets, but morphological differentiation was accelerated in dopaminergic neurons originating in the arcuate nucleus only. We then investigated whether physical contact between developing arcuate neurons and their target cells was a prerequisite of the morphological effect by interposing a semipermeable membrane between cultivated neurons and intermediate lobe cells in transwell culture dishes. The morphological effect was no longer observed under transwell coculture conditions, pointing to the involvement of membrane-bound molecules. Accordingly, the stimulating effect of coculture on arcuate dopaminergic neurons was completely abolished by the removal of polysialic acid on neural cell adhesion molecules by endoneuraminidase N treatment. Thus, maturation of A12 and A14 dopaminergic neurons exhibits differential susceptibility to intermediate lobe target cells, and polysialylated-NCAM is required for the contact-dependent effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1997.tb01649.x
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  • 7
    Electronic Resource
    Electronic Resource
    The interaction between F3 immunoglobulin domains and protein tyrosine phosphatases ζ/β triggers bidirectional signalling between neurons and glial cells (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 11 (1999), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: F3, a mouse glycosyl-phosphatidylinositol anchored molecule of the immunoglobulin superfamily, is known to influence axonal growth and fasciculation via multiple interactions of its modular immunoglobulin-like domains. We prepared an Fc chimeric molecule (F3IgFc) to identify molecules interacting with these domains and characterize the functional impact of the interactions. We affinity-isolated tenascin-C and isoforms of the proteoglycan-type protein tyrosine phosphatases ζ/β (PTPζ/RPTPβ) from extracts of developing mouse brain. We showed that both PTPζ/RPTPβ and tenascin-C can bind directly to F3, possibly in an exclusive manner, with the highest affinity for the F3–PTPζ/RPTPβ interaction. We observed a strong binding of F3IgFc-coated fluorospheres to astrocytes in neural primary cultures and to C6 astrocytoma cells, and demonstrated, in antibody perturbation experiments, that F3-Ig binding on astrocytes depends on its interaction with PTPζ/RPTPβ. We also found by confocal analysis that tenascin-C and PTPζ/RPTPβ were colocalized on astrocytes which suggests a complex interplay of interactions between PTPζ/RPTPβ, tenascin-C and F3. We showed that the interaction between PTPζ/RPTPβ and F3-Ig-like domains can trigger bidirectional signalling. C6 glia-expressed PTPζ/RPTPβ stimulated neurite outgrowth by cortical and cerebellar neurons, whereas preclustered F3IgFc specifically modified the distribution of phosphotyrosine labelling in these glial cells. Both effects could be prevented and/or mimicked by anti-F3 and anti-6B4PG antibodies. These results identify F3 and PTPζ/RPTPβ as potential mediators of a reciprocal exchange of information between glia and neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.1999.00521.x
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  • 8
    Electronic Resource
    Electronic Resource
    Distinct Effects of Recombinant Tenascin-R Domains in Neuronal Cell Functions and Identification of the Domain Interacting with the Neuronal Recognition Molecule F3/11 (1996)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 8 (1996), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have identified distinct domains of the rat extracellular matrix glycoprotein tenascin-R using recombinant fragments of the molecule that confer neuronal cell functions. In short-term adhesion assays (0.5 h), cerebellar neurons adhered best to the fragment representing the fibrinogen knob (FG), but also the fibronectin type Ill (FN) repeats 1-2 and 6-8. FG, FN1-2 and FN3-5 were the most repellent fragments for neuronal cell bodies. Neurites and growth cones were strongly repelled from areas coated with fragments containing the cysteine-rich stretch and the EGF-like domains (EGF-L), FN1-2, FN3-5 and FG. Polarization of morphology of hippocampal neurons was exclusively associated with FG, while EGF-L prevented neurite outgrowth altogether. The binding site of the neuronal receptor for tenascin-R, the immunoglobulin superfamily adhesion molecule F3/11, was localized to EGF-L. The combined observations show distinct, but also overlapping functions for the different tenascin-R domains. They further suggest the existence of multiple neuronal tenascin-R receptors which influence the response of neurons to their extracellular matrix environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1996.tb01262.x
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  • 9
    Electronic Resource
    Electronic Resource
    Different Domains of the F3 Neuronal Adhesion Molecule are Involved in Adhesion and Neurite Outgrowth Promotion (1994)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 6 (1994), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The mouse F3 cell surface protein is preferentially expressed on axons of subpopulations of neurons and is anchored to the membrane by a glycosyl-phosphatidylinositol group. It consists of six immunoglobulin-like domains and four fibronectin type III homologous repeats, and can be found both in membrane-anchored and soluble forms. We have previously established that F3 fulfils the operational criteria of a cell adhesion molecule when anchored to the plasma membrane and that its soluble form stimulates neurite initiation and neurite outgrowth. To further characterize F3-mediated adhesion and to investigate whether adhesion and neurite outgrowth promoting activities are displayed by different parts of the molecule, we (i) selected F3 transfected CHO cells expressing increasing levels of F3 at their surface and (ii) prepared transfectants expressing an F3 molecule with its fibronectin type III repeats deleted. We show that the F3 molecule mediates divalent-cation-independent, temperature-dependent binding. The levels of aggregation of F3 transfectants are proportional to the level of F3 expression. Transfectants expressing F3 deleted of the fibronectin type Ill repeats lose their adhesive properties; conversely, cells expressing wild-type F3 and treated with collagenase, specifically removing the immunoglobulin-like domains, are still able to aggregate. Therefore, in this model adhesion site(s) mapped to the fibronectin type III repeats. By contrast, transfectants expressing deleted F3, as well as the soluble forms of this F3 deleted molecule, were able to stimulate neurite outgrowth of sensory neurons similarly to wild-type F3. Our data indicate that F3 is a multifunctional molecule and that adhesion and neurite outgrowth promoting properties are expressed by distinct and independent domains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1994.tb00288.x
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  • 10
    Electronic Resource
    Electronic Resource
    A semaphorin code defines subpopulations of spinal motor neurons during mouse development (2005)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 21 (2005), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the spinal cord, motor neurons (MNs) with similar muscle targets and sensory inputs are grouped together into motor pools. To date, relatively little is known about the molecular mechanisms that control the establishment of pool-specific circuitry. Semaphorins, a large family of secreted and cell surface proteins, are important mediators of developmental processes such as axon guidance and cell migration. Here, we used mRNA in situ hybridization to study the expression patterns of semaphorins and their receptors, neuropilins and plexins, in the embryonic mouse spinal cord. Our data show that semaphorins and their receptors are differentially expressed in MNs that lie in distinct locations within the spinal cord. Furthermore, we report a combinatorial expression of class 3 (secreted) semaphorins and their receptors that characterizes distinct motor pools within the brachial and lumbar spinal cord. Finally, we found that a secreted semaphorin, Sema3A, elicits differential collapse responses in topologically distinct subpopulations of spinal MNs. These findings lead us to propose that semaphorins and their receptors might play important roles in the sorting of motor pools and the patterning of their afferent and efferent projections.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2005.04021.x
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