Modulated adhesion: a proposal for the role of myelin-associated glycoprotein in myelin wrapping.

1989 ◽  
Vol 35 (5) ◽  
pp. 717-720 ◽  
Author(s):  
J Attia ◽  
M Tropak ◽  
P W Johnson ◽  
W Newerly-Abranow ◽  
T Pawson ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Schwann Cells ◽  
Clinical Findings ◽  
Membrane Glycoprotein ◽  
Nervous Systems ◽  
Phosphorylation State ◽  
Phosphatase Activities ◽  
Cell Assays ◽  
Myelin Associated Glycoprotein

Abstract Myelin-associated glycoprotein (MAG) is a 100-kDa integral membrane glycoprotein expressed by oligodendrocytes and Schwann cells in the central and peripheral nervous systems, respectively. It is found first in loosely wrapped myelin and then periaxonally after compaction. Clinical findings, structural analysis, and cell assays indicate a role for MAG in adhesion. We propose that the phosphorylation state of MAG modulates its adhesion and that a minimum spatial requirement for the separation of the kinase and phosphatase activities postulated by this model may explain the correlation between axon size and myelination state.

scholarly journals Expression of recombinant myelin-associated glycoprotein in primary Schwann cells promotes the initial investment of axons by myelinating Schwann cells.

1990 ◽  
Vol 111 (3) ◽  
pp. 1171-1182 ◽  
Author(s):  
G C Owens ◽  
C J Boyd ◽  
R P Bunge ◽  
J L Salzer
Keyword(s):  
Schwann Cells ◽  
Sensory Neurons ◽  
Constitutive Expression ◽  
Integral Membrane Protein ◽  
Developmentally Regulated ◽  
Myelin Associated Glycoprotein ◽  
Normal Requirement

Myelin-associated glycoprotein (MAG) is an integral membrane protein expressed by myelinating glial cells that occurs in two developmentally regulated forms with different carboxyterminal cytoplasmic domains (L-MAG and S-MAG). To investigate the role of MAG in myelination a recombinant retrovirus was used to introduce a MAG cDNA (L-MAG form) into primary Schwann cells in vitro. Stably infected populations of cells were obtained that constitutively expressed MAG at the cell surface without the normal requirement for neuronal contact to induce expression. Constitutive expression of L-MAG did not affect myelination. In long term co-culture with purified sensory neurons, the higher level of MAG expression on infected Schwann cells was reduced to control levels on cells that formed myelin. On the other hand, unlike normal Schwann cells, infected Schwann cells associated with nonmyelinated axons or undergoing Wallerian degeneration expressed high levels of MAG. This suggests that a posttranscriptional mechanism modulates MAG expression during myelination. Immunostaining myelinating cultures with an antibody specific to L-MAG showed that L-MAG was normally transiently expressed at the earliest stages of myelination. In short term co-culture with sensory neurons, infected Schwann cells expressing only L-MAG segregated and ensheathed larger axons after 4 d in culture provided that an exogenous basal lamina was supplied. Similar activity was rarely displayed by control Schwann cells correlating with the low level of MAG induction after 4 d. These data strongly suggest that L-MAG promotes the initial investment by Schwann cells of axons destined to be myelinated.

scholarly journals Axonal regulation of Schwann cell integrin expression suggests a role for alpha 6 beta 4 in myelination.

1993 ◽  
Vol 123 (5) ◽  
pp. 1223-1236 ◽  
Author(s):  
S Einheber ◽  
T A Milner ◽  
F Giancotti ◽  
J L Salzer
Keyword(s):  
Schwann Cell ◽  
Schwann Cells ◽  
Basal Lamina ◽  
Cell Contact ◽  
Myelin Associated Glycoprotein ◽  
Dorsal Root Ganglia Neurons ◽  
Outer Plasma Membrane

Ensheathment and myelination of axons by Schwann cells in the peripheral nervous system requires contact with a basal lamina. The molecular mechanism(s) by which the basal lamina promotes myelination is not known but is likely to reflect the activity of integrins expressed by Schwann cells. To initiate studies on the role of integrins during myelination, we characterized the expression of two integrin subunits, beta 1 and beta 4, in an in vitro myelination system and compared their expression to that of the glial adhesion molecule, the myelin-associated glycoprotein (MAG). In the absence of neurons, Schwann cells express significant levels of beta 1 but virtually no beta 4 or MAG. When Schwann cells are cocultured with dorsal root ganglia neurons under conditions promoting myelination, expression of beta 4 and MAG increased dramatically in myelinating cells, whereas beta 1 levels remained essentially unchanged. (In general agreement with these findings, during peripheral nerve development in vivo, beta 4 levels also increase during the period of myelination in sharp contrast to beta 1 levels which show a striking decrease.) In cocultures of neurons and Schwann cells, beta 4 and MAG appear to colocalize in nascent myelin sheaths but have distinct distributions in mature sheaths, with beta 4 concentrated in the outer plasma membrane of the Schwann cell and MAG localized to the inner (periaxonal) membrane. Surprisingly, beta 4 is also present at high levels with MAG in Schmidt-Lanterman incisures. Immunoprecipitation studies demonstrated that primary Schwann cells express beta 1 in association with the alpha 1 and alpha 6 subunits, while myelinating Schwann cells express alpha 6 beta 4 and possibly alpha 1 beta 1. beta 4 is also downregulated during Wallerian degeneration in vitro, indicating that its expression requires continuous Schwann cell contact with the axon. These results indicate that axonal contact induces the expression of beta 4 during Schwann cell myelination and suggest that alpha 6 beta 4 is an important mediator of the interactions of myelinating Schwann cells with the basal lamina.

Role of Peripheral Nerve-Derived Fibroblasts and Schwann Cells in CD40/CD40L and CD80/CD86-Mediated Rejection

2006 ◽  
Vol 22 (06) ◽  
Author(s):  
Deborah Yu ◽  
Sherri Wood ◽  
Keri Smith ◽  
Keith Bishop ◽  
Paul Cederna
Keyword(s):  
Peripheral Nerve ◽  
Schwann Cells

The role of Constitutional Courts in Transitional Justice: Colombia and South Africa

2016 ◽  
Vol 9 (15) ◽  
Author(s):  
Nadiehezka Paola Palencia Tejedor
Keyword(s):  
South Africa ◽  
Structural Analysis ◽  
Transitional Justice ◽  
Critical Analysis ◽  
Historical Context ◽  
Constitutional Courts ◽  
Political Background ◽  
Similarities And Differences ◽  
Peace And Reconciliation

This work focuses on a compared analysis of the South Afri- can decision related to the “peace and reconciliation act” of this country’s Parliament, and the Colombian decision regarding the amendment of the constitution called “The juridical framework for the peace.” Turning to the structure, it is developed in three major topics: 1. It provides a brief of the historical context, political background and an overview of the two decisions.2. It gives a structural analysis of the powers that each Court has and the nature of the constitutional mechanism through which both Courts decided the constitutionality of the said norms 3. It presents a critical analysis on the similarities and differences between the two systems and judgments. It presents some con- clusions. 

Semantic And Structural Properties Of The Banking And Financial Terminology Of The Uzbek Language

2020 ◽  
Vol 2 (08) ◽  
pp. 610-617
Author(s):  
Ekaterina Turakulovna Shirinova
Keyword(s):  
Structural Analysis ◽  
Structural Properties ◽  
Human Factor

This article discusses information on the study of terminology in Uzbek and world linguistics. Thematic grouping of banking and financial terms, which play an important role in Uzbek language vocabulary, is considered. The author gives the criteria for the distribution of terms into thematic groups, their peculiar properties examples to substantiate the hypothesis. The paradigmatic relations between the terms of this sphere are indicated. A structural analysis of the banking and financial terms of the Uzbek language is carried out.  On the basis of the anthropocentric approach, the role of the human factor in the banking and financial terminology of the Uzbek language is studied. Cognitive metaphors that exist in the terminology are considered.

What is the role of fear and escape/avoidance in chronic pain? Models, structural analysis and future directions

2012 ◽  
Vol 2 (3) ◽  
pp. 295-303 ◽  
Author(s):  
Gordon JG Asmundson ◽  
Holly A Parkerson ◽  
Mark Petter ◽  
Melanie Noel
Keyword(s):  
Chronic Pain ◽  
Structural Analysis ◽  
Future Directions ◽  
Pain Models

Unipolarity

2008 ◽  
Vol 61 (1) ◽  
pp. 188-213 ◽  
Author(s):  
Robert Jervis
Keyword(s):  
United States ◽  
Structural Analysis ◽  
Current System ◽  
Nuclear Proliferation ◽  
Balance Of Power ◽  
The United States

In analyzing the current unipolar system, it is useful to begin with structure. No other state or plausible coalition can challenge the unipole's core security, but this does not mean that all its values are safe or that it can get everything that it wants. Contrary to what is often claimed, standard balance of power arguments do not imply that a coalition will form to challenge the unipole. Realism also indicates that rather than seeking to maintain the system, the unipole may seek further expansion. To understand the current system requires combining structural analysis with an appreciation of the particular characteristics of the current era, the United States, and its leaders. Doing so shows further incentives to change the system and highlights the role of nuclear proliferation in modifying existing arrangements.

Essential Role of Src Suppressed C Kinase Substrates in Schwann Cells Adhesion, Spreading and Migration

2008 ◽  
Vol 34 (5) ◽  
pp. 1002-1010 ◽  
Author(s):  
Meijuan Yan ◽  
Chun Cheng ◽  
Jing Jiang ◽  
Yonghua Liu ◽  
Ying Gao ◽  
...  
Keyword(s):  
Schwann Cells ◽  
Essential Role ◽  
And Migration ◽  
Kinase Substrates

scholarly journals The role of wild ruminants in the epidemiology of bovine petechial fever

1975 ◽  
Vol 74 (2) ◽  
pp. 245-250 ◽  
Author(s):  
D. R. Snodgrass ◽  
L. H. Karstad ◽  
J. E. Cooper
Keyword(s):  
Clinical Findings ◽  
Wild Ruminants ◽  
Experimental Inoculation

SUMMARYAfter experimental inoculation of Cytoecetes ondiri, the agent of bovine petechial fever (BPF), multiplication occurred in impala, bushbuck, Thomson's gazelles and wildebeest, as shown by infectivity studies and clinical findings. Similar attempts to infect one eland failed.As a sequel to this, blood and spleen samples were collected from four species of wild ruminants in an area where BPF was endemic. Isolations of C. ondiri were made from three of five bushbuck, but not from any other species.

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