scholarly journals Schwann cell myelination: induction by exogenous basement membrane-like extracellular matrix.

1986 ◽  
Vol 102 (6) ◽  
pp. 2254-2263 ◽  
Author(s):  
D J Carey ◽  
M S Todd ◽  
C M Rafferty
Keyword(s):  
Extracellular Matrix ◽  
Cell Differentiation ◽  
Basement Membrane ◽  
Schwann Cell ◽  
Schwann Cells ◽  
Nerve Fibers ◽  
Nerve Cells ◽  
Collagen Type Iv ◽  
The Matrix ◽  
Schwann Cell Differentiation

Exposing rat Schwann cells co-cultured with nerve cells to a reconstituted basement membrane induced the formation of myelin segments by Schwann cells. This occurred in a serum-free culture medium in which, in the absence of this matrix, Schwann cells proliferate but fail to differentiate. This reconstituted basement membrane was prepared from solubilized extracellular matrix proteins synthesized by a basement membrane-producing murine tumor. The major constituents of this reconstituted matrix are collagen type IV, laminin, heparan sulfate proteoglycan, entactin, and nidogen. The matrix also elicited striking morphological changes in Schwann cells, inducing them to spread longitudinally along the nerve fibers (a necessary early step in the process of ensheathment of nerve fibers). Several observations indicated that the effect of the matrix was exerted directly on Schwann cells and not indirectly through an effect on nerve cells. First, the matrix-induced cell spreading occurred only in areas in which Schwann cells directly contacted the matrix; Schwann cells that were associated with the same nerve fibers but that did not themselves directly contact the matrix did not exhibit spreading. Second, the matrix-induced alteration in Schwann cell morphology was observed in cultures in which the nerve cells were removed. These results provide direct evidence that basement membrane contact induces normal Schwann cell differentiation, and support the idea that Schwann cell differentiation in vivo may be regulated by the appearance of the basement membrane, which normally envelops terminally differentiating Schwann cells.

Schwann Cell Differentiation in vitro: Extracellular Matrix Deposition and Interaction

1986 ◽  
Vol 8 (3) ◽  
pp. 182-196 ◽  
Author(s):  
A. Baron-Van Evercooren ◽  
A. Gansmüller ◽  
M. Gumpel ◽  
N. Baumann ◽  
H.K. Kleinman
Keyword(s):  
Extracellular Matrix ◽  
Cell Differentiation ◽  
Schwann Cell ◽  
Matrix Deposition ◽  
Extracellular Matrix Deposition ◽  
Schwann Cell Differentiation

scholarly journals Effects of inhibition of proteoglycan synthesis on the differentiation of cultured rat Schwann cells.

1987 ◽  
Vol 105 (2) ◽  
pp. 1013-1021 ◽  
Author(s):  
D J Carey ◽  
C M Rafferty ◽  
M S Todd
Keyword(s):  
Plasma Membrane ◽  
Basement Membrane ◽  
Schwann Cell ◽  
Schwann Cells ◽  
Gel Filtration ◽  
Specific Inhibitor ◽  
Proteoglycan Synthesis ◽  
Collagen Type Iv ◽  
Type Iv ◽  
Associated Proteins

Schwann cells synthesize two heparan sulfate proteoglycans, one that is a component of the Schwann cell basement membrane and a smaller one that is an integral component of the Schwann cell plasma membrane. To determine the functions of these molecules, Schwann cell-nerve cell cultures were grown in medium containing a specific inhibitor of proteoglycan biosynthesis, 4-methylumbelliferyl-beta-D-xyloside. Treatment with 1 mM beta-D-xyloside caused a 90% reduction in the accumulation of 35SO4-labeled proteoglycans in the cell layer of the cultures. Gel filtration analysis revealed that both the basement membrane and plasma membrane proteoglycans were affected. Inhibition of proteoglycan biosynthesis was accompanied by an inhibition of laminin deposition into extracellular matrix as determined by immunostaining of cultures and by immunoblotting of cell-associated proteins. This occurred even though there was no decrease in the amount of laminin detected in the medium of beta-D-xyloside-treated cultures. Deposition of collagen type IV was similarly affected. In addition, there was no myelin produced in beta-D-xyloside treated cultures. However, when beta-xyloside-treated cultures were supplied with exogenous basement membrane, Schwann cells produced numerous myelin segments. These results indicate that Schwann cell proteoglycans play an essential role in basement membrane assembly, and that the integral plasma membrane proteoglycan is not required for the basement membrane to exert its effects on Schwann cell differentiation.

scholarly journals Nectin-like proteins mediate axon–Schwann cell interactions along the internode and are essential for myelination

2007 ◽  
Vol 178 (5) ◽  
pp. 861-874 ◽  
Author(s):  
Patrice Maurel ◽  
Steven Einheber ◽  
Jolanta Galinska ◽  
Pratik Thaker ◽  
Isabel Lam ◽  
...  
Keyword(s):  
Nervous System ◽  
Cell Differentiation ◽  
Schwann Cell ◽  
Peripheral Nervous System ◽  
Schwann Cells ◽  
Molecular Complexes ◽  
Hairpin Rna ◽  
Nodal Region ◽  
Short Hairpin ◽  
Schwann Cell Differentiation

Axon–glial interactions are critical for the induction of myelination and the domain organization of myelinated fibers. Although molecular complexes that mediate these interactions in the nodal region are known, their counterparts along the internode are poorly defined. We report that neurons and Schwann cells express distinct sets of nectin-like (Necl) proteins: axons highly express Necl-1 and -2, whereas Schwann cells express Necl-4 and lower amounts of Necl-2. These proteins are strikingly localized to the internode, where Necl-1 and -2 on the axon are directly apposed by Necl-4 on the Schwann cell; all three proteins are also enriched at Schmidt-Lanterman incisures. Binding experiments demonstrate that the Necl proteins preferentially mediate heterophilic rather than homophilic interactions. In particular, Necl-1 on axons binds specifically to Necl-4 on Schwann cells. Knockdown of Necl-4 by short hairpin RNA inhibits Schwann cell differentiation and subsequent myelination in cocultures. These results demonstrate a key role for Necl-4 in initiating peripheral nervous system myelination and implicate the Necl proteins as mediators of axo–glial interactions along the internode.

scholarly journals Schwann cells use a novel collagen-dependent mechanism for fibronectin fibril assembly

1998 ◽  
Vol 111 (18) ◽  
pp. 2763-2777 ◽  
Author(s):  
M.A. Chernousov ◽  
R.C. Stahl ◽  
D.J. Carey
Keyword(s):  
Extracellular Matrix ◽  
Schwann Cells ◽  
Collagen Type ◽  
Collagen Type I ◽  
Collagen Type Iv ◽  
Type I ◽  
Type Iv ◽  
The Matrix ◽  
Fibronectin Fibrils ◽  
Dependent Mechanism

Cultured rat Schwann cells were stimulated to deposit fibrillar extracellular matrix by treatment with ascorbic acid in the absence of nerve cells. Immunofluoresence staining of the matrix showed that it contains collagens types I and IV, fibronectin and perlecan but not laminin. Collagen type IV, fibronectin and perlecan co-distributed completely in the matrix fibrils, whereas collagen type I was present in only a subset of these fibrils. Time course studies indicated that collagen type I fibrils appear at late stages of matrix formation. Digestion of Schwann cell extracellular matrix with collagenase effectively disrupted most of the matrix including fibronectin fibrils. This was in contrast with fibroblasts, where collagenase treatment removed collagen with no visible effect on fibronectin fibrils. alpha5 integrin was expressed on the cell surface of Schwann cells and partially codistributed with fibronectin-containing fibrils. This suggests that the inability of Schwann cells to deposit fibronectin-containing matrix through a conventional, collagen-independent mechanism was not due to the lack of fibronectin-binding integrins on their cell surface. Polyclonal anti-fibronectin antibodies inhibited the deposition of fibronectin into the matrix fibrils, whereas collagen type IV fibrils were generally unaffected. Growth of Schwann cells on collagen type IV-coated substrate in the absence of ascorbate induced deposition of fine fibronectin fibrils. These results suggest that Schwann cells use an apparently novel, collagen type IV-dependent mechanism for the deposition of fibronectin into their extracellular matrix.

scholarly journals Antibodies to the L1 adhesion molecule inhibit Schwann cell ensheathment of neurons in vitro.

1989 ◽  
Vol 109 (6) ◽  
pp. 3095-3103 ◽  
Author(s):  
B Seilheimer ◽  
E Persohn ◽  
M Schachner
Keyword(s):  
Cell Differentiation ◽  
Schwann Cell ◽  
Schwann Cells ◽  
Adhesion Molecule ◽  
Neuronal Cell ◽  
Dorsal Root Ganglion Neurons ◽  
Neural Adhesion Molecule ◽  
Ganglion Neurons ◽  
Schwann Cell Differentiation

To investigate whether neural adhesion molecules are involved in neuron-induced Schwann cell differentiation, cocultures of pure dorsal root ganglion neurons, and Schwann cells were maintained in the presence of antibodies to evaluate possible perturbing effects. Several parameters characteristic of differentiating Schwann cells were studied, such as transition of spindle-shaped to flattened, i.e., more epithelioid morphology, association with neuronal cell bodies, ensheathment of neurites, production of basal lamina and collagen fibrils, and expression of the myelin associated glycoprotein (MAG). A complete ablation of Schwann cell differentiation in all features studied was seen with antibodies to the neural adhesion molecule L1. Antibodies to N-CAM did not reduce the association of Schwann cells with neurites but abolished the interdigitation of Schwann cell processes into neurite bundles, while leaving the other parameters studied unaffected. Fab fragments of antibodies to J1, MAG, and mouse liver membranes did not interfere with the manifestation of any of these parameters. None of the antibodies changed incorporation of [3H]thymidine into Schwann cells.

scholarly journals Differentiation of axon-related Schwann cells in vitro. I. Ascorbic acid regulates basal lamina assembly and myelin formation.

1987 ◽  
Vol 105 (2) ◽  
pp. 1023-1034 ◽  
Author(s):  
C F Eldridge ◽  
M B Bunge ◽  
R P Bunge ◽  
P M Wood
Keyword(s):  
Ascorbic Acid ◽  
Cell Differentiation ◽  
Schwann Cell ◽  
Schwann Cells ◽  
Basal Lamina ◽  
Defined Medium ◽  
Acid Oxidase ◽  
Myelin Formation ◽  
Schwann Cell Differentiation ◽  
Cells Cultured

Rat Schwann cells cultured with dorsal root ganglion neurons in a serum-free defined medium fail to ensheathe or myelinate axons or assemble basal laminae. Replacement of defined medium with medium that contains human placental serum (HPS) and chick embryo extract (EE) results in both basal lamina and myelin formation. In the present study, the individual effects of HPS and EE on basal lamina assembly and on myelin formation by Schwann cells cultured with neurons have been examined. Some batches of HPS were unable to promote myelin formation in the absence of EE, as assessed by quantitative evaluation of cultures stained with Sudan black; such HPS also failed to promote basal lamina assembly, as assessed by immunofluorescence using antibodies against laminin, type IV collagen, and heparan sulfate proteoglycan. The addition of EE or L-ascorbic acid with such HPS led to the formation of large quantities of myelin and to the assembly of basal laminae. Pretreatment of EE with ascorbic acid oxidase abolished the EE activity, whereas trypsin did not. Other batches of HPS were found to promote both basal lamina and myelin formation in the absence of either EE or ascorbic acid. Ascorbic acid oxidase treatment or dialysis of these batches of HPS abolished their ability to promote Schwann cell differentiation, whereas the subsequent addition of ascorbic acid restored that ability. Ascorbic acid in the absence of serum was relatively ineffective in promoting either basal lamina or myelin formation. Fetal bovine serum was as effective as HPS in allowing ascorbic acid (and several analogs but not other reducing agents) to manifest its ability to promote Schwann cell differentiation. We suggest that ascorbic acid promotes Schwann cell myelin formation by enabling the Schwann cell to assemble a basal lamina, which is required for complete differentiation.

scholarly journals Schwann cells of the myelin-forming phenotype express neurofilament protein NF-M.

1992 ◽  
Vol 118 (2) ◽  
pp. 397-410 ◽  
Author(s):  
B M Kelly ◽  
C S Gillespie ◽  
D L Sherman ◽  
P J Brophy
Keyword(s):  
Cell Differentiation ◽  
Schwann Cell ◽  
Schwann Cells ◽  
Early Stage ◽  
Intracellular Camp ◽  
Neurofilament Protein ◽  
Composition And Structure ◽  
Early Effects ◽  
Schwann Cell Differentiation ◽  
Camp Levels

Immature Schwann cells of the rat sciatic nerve can differentiate into myelin-forming or non-myelin-forming cells. The factors that influence this divergent development are unknown but certain markers such as galactocerebroside distinguish the two cell populations at an early stage of Schwann cell differentiation. Because myelination requires extensive changes in cell morphology, we have investigated the composition and structure of the Schwann cell cytoskeleton at a time when these cells become committed to myelination. Here we show that Schwann cells express a cytoskeletal protein of M(r) 145 before diverging into the myelin-forming path, i.e., before they acquire cell-surface galactocerobroside. The p145 protein has the characteristics of an intermediate filament (IF) protein and immunoelectron microscopy shows that it colocalizes with vimentin, which suggests that these two proteins can coassemble into IFs. Elevated intracellular cAMP levels, which can mimic some of the early effects of axons on Schwann cell differentiation, induced p145 synthesis, therefore, we conclude that myelin-forming Schwann cells express this protein at a very early stage in their development. Immunological comparisons with other IF proteins revealed a close similarity between p145 and the neurofilament protein NF-M; the identification of p145 as NF-M was confirmed by isolating and sequencing a full-length clone from a Schwann cell cDNA library. These data demonstrate that Schwann cells remodel their IFs by expressing NF-M before acquiring the myelin-forming phenotype and that IF proteins of the neurofilament-type are not restricted to neurons in the vertebrate nervous system.

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