Rapid Axonal Transport of the Neural Cell Adhesion Molecule (original) (raw)
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The Journal of Cell Biology, 1985
This study represents a global survey of the times of the first appearance of the neuron-glia cell adhesion molecule (Ng-CAM) in various regions and on particular cells of the chick embryonic nervous system. Ng-CAM, originally characterized by means of an in vitro binding assay between glial cells and brain membrane vesicles, first appears in development at the surface of early postmitotic neurons. By 3 d in the chick embryo, the first neurons detected by antibodies to Ng-CAM are located in the ventral neural tube; these precursors of motor neurons emit well-stained fibers to the periphery. To identify locations of appearance of Ng-CAM in the peripheral nervous system (PNS), we used a monoclonal antibody called NC-1 that is specific for neural crest cells in early embryos to show the presence of numerous crest cells in the neuritic outgrowth from the neural tube; neither these crest cells nor those in ganglion rudiments bound anti-Ng-CAM antibodies. The earliest neurons in the PNS stained by anti-Ng-CAM appeared by 4 d of development in the cranial ganglia. At later stages and progressively, all the neurons and neurities of the PNS were found to contain Ng-CAM both in vitro and in vivo. Many central nervous system (CNS) neurons also showed Ng-CAM at these later stages, but in the CNS, the molecule was mostly associated with neuronal processes (mainly axons) rather than with cell bodies; this regional distribution at the neuronal cell surface is an example of polarity modulation.
Axonal transport of macromolecules I. Protein migration in the central nervous system
Experimental Brain Research, 1971
The avian visual system has been used to study the transport of proteins and their precursors along the optic tract. Various labeled compounds were injected into a single eye of new hatched chicks. The radioactivity of components in the optic lobe that was contralateral to, and innervated by, the injected eye was compared to radioactivity in the ipsilateral lobe, not innervated by the treated eye. Proteins migrating from the ganglion cells of the retina to the optic tectum seemed to be relatively stable and may be rich in praline and glycine. Microtubular protein migrated at a rate similar to nonmicrotubule soluble protein, and slower than particulate protein. With the exception of y-aminobutyric acid, transport of free amino acids occurred to only a minor extent. Following monocular injection of tritiated fucose, a rapid asymmetry in the specific activities of protein from contralateral and ipsilateral lobes, was established. Thus the more rapidly migrating proteins may be attached to glycosidic residues. The carbohydrate moeity of these glycoproteins is attached in the nerve cell body, prior to their axonal transport to the optic tectum. There was no evidence for transneuronal transfer of protein as in no cai;e was a differential in specific activity observed in labeled protein from paired cerebral hemispheres.
Differential distribution of cell adhesion molecules during histogenesis of the chick nervous system
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1986
We have compared the expression of the neural cell adhesion molecule (N-CAM) and the neuron-glial cell adhesion molecule (Ng-CAM) during histogenesis of the chick nervous system. Data from immunohistochemistry and photometry were combined to construct maps of the overall distribution and dynamics of CAM appearance and disappearance. Each CAM appeared in a characteristic spatial and temporal pattern in various areas during cell movement, fiber outgrowth, tract formation, and myelination. N-CAM was more uniformly distributed than Ng-CAM and was present on all neural cell bodies and processes of the CNS and PNS. In the adult, the staining pattern of N-CAM remained similar to that in the embryo, although the staining intensity was diminished. During embryonic development, Ng-CAM was expressed on extending neurites and migrating neurons. The appearance Ng-CAM in the CNS was correlated particularly with times of cell migration in spinal cord and cerebellum, and in regions undergoing neuri...
The neural cell adhesion molecule (NCAM) in development and plasticity of the nervous system
Experimental Gerontology, 1998
The neural cell adhesion molecule (NCAM) is a member of the immunoglobulin superfamily and is strongly expressed in the nervous system. NCAM is found in three major forms, of which two-NCAM-140 and NCAM-180 -are transmembrane proteins, while the third-NCAM-120 -is attached to the membrane via a glycosylphosphatidyl inositol anchor. In addition, soluble NCAM forms exist in brain, cerebrospinal fluid, and plasma. NCAM mediates cell adhesion through homophilic as well as through heterophilic interactions. Following NCAM binding, transmembrane signalling is believed to be activated, resulting in increased intracellular calcium. By mediating cell adhesion to other cells and to the extracellular matrix and by activating intracellular signaling pathways, NCAM influences cell migration, neurite extension, and fasciculation, and possibly formation of synapses in the brain. From studies on NCAM knock-out mice, NCAM have been shown to be crucial for the formation of the olfactory bulb and the mossy fiber system in the hippocampus. In addition, NCAM is important for neuronal plasticity in the adult brain associated with learning and regeneration.
1987
Cytoskeletal protein transport and metabolism are studied in the somatic motor and parasympathetic axons of the chicken oculomotor system. Kinetic analyses of pulse-labeled proteins indicate that the neurofilaments are transported 2–3 times more rapidly in the somatic motor axons than in the parasympathetic axons. By contrast, the transport rates of the slow component b (SCb) proteins are very similar in these axons. The parasympathetic axons terminate in the ciliary ganglion, and radiolabeling curves from the ciliary ganglion can be used to study the kinetics of cytoskeletal protein removal from the terminals. The rate of removal directly determines the residence time of the cytoskeletal proteins in the ciliary ganglion, and the residence time directly affects the shape and amplitude of the transport curves of the ganglion. A computer model was used to analyze these transport curves and to determine the half-residence time of the cytoskeletal proteins in the terminal regions. From ...
Glia, 1998
Neural cell adhesion molecules (NCAMs) constitute a group of cell surface glycoproteins that control cell-cell interactions and play important morphoregulatory roles in the developing and regenerating nervous system. NCAMs exist in a variety of isoforms differing in the cytoplasmic domain and/or their content in sialic acid. The highly sialylated form (PSA-NCAM) is expressed by neurons, whereas it is believed that the less sialylated NCAM forms are synthesised by astrocytes. Moreover, little is known about the molecular sequence of the events that contribute to its expression at the cell surface. Here we report that during the proliferation of cortical astrocytes, at 4 days in primary culture, these cells expressed PSA-NCAM as well as NCAM 180. Then, during cell differentiation these isoforms progressively disappeared and the NCAM 140 became predominant. By immunofluorescence and immunocytochemistry studies we also show that PSA-NCAM and NCAM are first observed in small cytoplasmic spots or vesicles, located in or near the Golgi apparatus, as demonstrated by their co-localization with labelled wheat germ agglutinin (WGA) in this cell organelle. Thereafter, immunostained cytoplasmic NCAM gradually disappeared and became detectable at the cell surface of differentiating astrocytes. We also describe for the first time sialyltransferase activity in these cells and report that the levels of this activity correlated with the decrease in PSA-NCAM expression during the differentiation of astrocytes. These results will contribute to our understanding of the PSA and NCAM intracellular transport pathways and their expression at the cell surface. Moreover, the presence of PSA-NCAM in astrocytes suggests their possible role in nerve branching, fasciculation, and synaptic plasticity.
The Journal of …, 1987
Many of the structural and functional differences between axons are thought to reflect underlying differences in the biochemical composition and dynamic aspects of the axonal cytoskeleton and cytomatrix. In this study we investigated how the composition of the 2 slow components of axonal transport, SCa and SCb, which convey the cytoskeleton and cytomatrix, differs in axons that are structurally and functionally distinct. For this comparison we analyzed axons of retinal ganglion cells in the optic nerve (ON), axons of dorsal root ganglion (DRG) cells, and axons of ventral motor neurons (VMN) in adult rats. 35S-Methionine-labeled proteins transported with the peak of SCa and SCb were analyzed using high-resolution 2-dimensional polyacrylamide gels (PD-PAGE) and fluorography, and the amounts of major SCa and SCb proteins were quantified. The polypeptide composition of both SCa and SCb was found to be largely similar in DRG and VMN axons, but major qualitative as well as quantitative differences between these axons and ON axons were found. Notable among these were higher ratios of neurofilament protein to tubulin in SCa in DRG and VMN axons compared to ON axons, and significantly larger amounts of 2 microtubule-associated proteins relative to tubulin in SCa of ON axons than in both VMN and DRG axons. Tubulin was the major SCb protein in VMN and DRG axons, but it was not present in SCb in ON axons. Additionally, relatively larger amounts of 2 metabolic enzymes, creatine phosphokinase and nerve-specific enolase, were present in SCb in ON axons than in DRG or VMN axons. The results indicate that significant biochemical heterogeneity among different types of axons can be identified by examining the slow components of axonal transport.
Electrophoretic Analysis of Axonally Transported Proteins in Toad Retinal Ganglion Cells
Journal of Neurochemistry, 1981
Abstract: As a preliminary step to studying changes in axonal transport in regenerating neurons, we have analyzed the composition and organization of polypeptides normally axonally transported in a neuronal system capable of regeneration, i.e., the retinal ganglion cells of the toad, Bufo marinus. We labeled proteins synthesized in the retina with 35S-methionine and subsequently used one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis to analyze labeled, transported proteins in tissues containing segments of the axons (the optic nerve, optic tract, and optic tecta) of the retinal ganglion cells. The transported polypeptides could be divided into five groups according to their apparent transport velocities. Many of the polypeptides of each group were electrophoretically similar to polypeptides of corresponding groups previously described in rabbit and guinea pig retinal ganglion cells, and in some cases, additional properties of the polypeptides indicated that the transported materials of the two vertebrate classes were homologous. These results serve two purposes. First they establish the retinal ganglion cells of the toad Bufo marinus as a model system in which changes in gene expression related to regeneration may be studied. Second they show that the organization and many aspects of the composition of axonal transport in retinal ganglion cells have been conserved in animals as unrelated as amphibians and mammals.
The Journal of neuroscience : the official journal of the Society for Neuroscience, 1990
To investigate cytoskeletal changes associated with axonal regrowth from damaged nerve cells in the mammalian CNS, we examined the slow transport of axonal proteins during the regeneration of adult rat retinal ganglion cell (RGC) axons. Although normally such RGC axons do not regrow after injury in the CNS, they can extend several centimeters when their nonneuronal environment is changed by replacing the optic nerve (ON) with a grafted segment of peripheral nerve (PN). Proteins transported in axons of RGCs from intact control and PN-grafted animals were labeled by an intraocular injection of 35S-methionine and examined 4-60 days later by SDS PAGE. During RGC regeneration into PN grafts, the transport rate of tubulin and neurofilament increased twofold, whereas that of actin decreased to nearly one third of its normal rate. Thus, in these regenerating RGC axons, all three major cytoskeletal proteins were largely transported within a single rate component rather than in the two separa...