Oligodendrocytes myelination

Myelinating oligodendrocytes have been studied extensively [5,30] (see Ch. 4). Examination of the CNS during myelinogenesis (Fig. 1-15) reveals connections between the cell body and the myelin sheath [31] however, connections between these elements have never been demonstrated in a normal adult animal, unlike the PNS counterpart, the Schwann cell. In contrast to the Schwann cell (see below), the oligodendrocyte is capable of producing many internodes of myelin simultaneously. It has been estimated that oligodendrocytes in the optic nerve produce... 

FIGURE 1-15 A myelinating oligodendrocyte, nucleus (N), from the spinal cord of a 2-day-old kitten extends cytoplasmic connections to at least two myelin sheaths arrows). Other myelinated and unmyelinated fibers at various stages of development, as well as glial processes, are seen in the surrounding neuropil. Xl2,750. 

Small amounts of proteins characteristic of cells and membranes in general can also be found in myelin. There is evidence that tubulin is an authentic myelin-related component (Fig. 4-12B, D, CNS myelin). The 48kDa myelin/oligodendrocyte-specific protein (MOSP) is a component found only in CNS myelin and oligodendroglial membranes, which appears to associate with tubulin [41]. 

In brief, EAE can be induced by immunization with several encephalitogenic proteins from myelin, most notably MBP, PLP and myelin-oligodendrocyte glycoprotein (MOG). MBP was the first protein shown to cause EAE, and this classical form of the disease is mediated primarily by CD4+, MHC class II restricted T cells, because it can be transferred from an immunized animal to a naive animal using these cells. These data document the importance of CD4+ lymphocytes for EAE induction, but additional pathogenic roles for other T cell populations are possible, especially in later stages of the disease. Also, there is... 

Iglesias, A., Bauer, J., Litzenburger, T. etal. T- and B-cell responses to myelin oligodendrocyte glycoprotein in experimental autoimmune encephalomyelitis and multiple sclerosis. Glia 36 220-234,2001. 

INSR insulin receptor MOG myelin-oligodendrocyte glycoprotein... 

Multiple sclerosis 58 64% myelin oligodendrocyte glycoprotein Infectious agents (Epstein-Barr virus), solvents, ultraviolet radiation/vitamin D, tobacco... 

Myelin Oligodendrocyte Glycoprotein (MOG) Peptide Fragment Rat (Sigma-Aldrich, MO, USA). 

Multiple sclerosis (MS) is the most frequent inflammatory demyeli-nating disease of the central nervous system that affects worldwide about 2.5 million people with no cure. Myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (MOG-induced EAE) in DA rats is an appropriate model for therapeutic testing, sharing many features with human multiple sclerosis. 

Figure 16.1 A neuron with accompanying astrocyte and myelinating oligodendrocyte.

Stefferl, A., Schubart, A., Storch, M., Amini, A., Mather, I., Lassmann, H., Linington, C. 2000. Butyrophilin, a milk protein, modulates the encephalitogenic T cell response to myelin oligodendrocyte glycoprotein in experimental autoimmune encephalomyelitis. J Immunol. 165, 2859-2865. 

Increased PLPl gene dosage affects expression of other myelin proteins, particularly MBP which is lower in homozygotes in both myelin and early myelinating oligodendrocytes (Karim et al., 2007). As shown in the jimpy mouse, there is a drastic decrease of the 14 kDa isoform of MBP (Campagnoni et al., 1984). 

It is conceivable that the process of remyelination mimics that of myelination during development, but the key factors affecting the differentiation and maturation of OPCs into myelinating oligodendrocytes do not perfectly trigger remyelination... 

Register B, Ben-Hur T, Dubois-Dalcq M (1999) From neural stem cells to myelinating oligodendrocytes. Mol Cell Neurosci 14 287-300... 

Myelin/oligodendrocyte specific protein (MOSP) MOSP is a novel surface protein which is exclusively expressed in CNS myelin. It also plays an important role in membrane/cy toskeleton interactions during the formation and maintenance of CNS myelin. 

Johns TG, Bernard CC (1999) The structure and function of myelin oligodendrocytes glycoprotein. J Neurochem 72 1—9. 

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