Microtubule Organization and Stability in the Oligodendrocyte

Abstract

The oligodendrocyte is the glial cell responsible for the formation and maintenance of CNS myelin. Because the development of neuronal morphology is known to depend on the presence of highly organized microtubule arrays, it may be hypothesized that the properties of microtubules influence the form and function of oligodendrocytes. The goals of the present study were to define the physical attributes of microtubules in oligodendrocytes maintained in vitro. The results of electron and confocal microscopy indicate that microtubules are present throughout the cell bodies and large and small processes of oligodendrocytes and are rarely associated with discrete microtubule-organizing centers. A modified "hooking" protocol demonstrated that the polarity orientation of microtubules is uniformly plus-end distal in small oligodendrocyte processes, compared with a nonuniform, predominantly plus-end distal orientation in large processes. Oligodendrocytes were exposed to the microtubule-depolymerizing drug nocodazole to examine microtubule stability in these cells. The results suggest that oligodendrocyte microtubules can be resolved into at least three distinct microtubule populations that differ in their kinetics of depolymerization in the presence of nocodazole. These findings suggest that the properties of the oligodendrocyte microtubule array reflect the functions of the different regions of this highly specialized cell.

Isolation and Expression Pattern of Human Unc-33-Like Phosphoprotein 6/Collapsin Response Mediator Protein 5 (Ulip6/CRMP5): Coexistence with Ulip2/CRMP2 in Sema3A- Sensitive Oligodendrocytes

“…Sema3A, via Ulip2/CRMP2 or Ulip6/CRMP5, may act on the dynamics of microtubules, leading to the decrease in process extension. Several results support this hypothesis: (1) microtubules are present in oligodendrocytes and reflect oligodendrocyte function (Lunn et al, 1997), (2) Ulip2/CRMP2 mediates the dynamics of microtubules , and (3) protein kinase, which could phosphorylate the numerous phosphorylation sites of the Ulip/CRMPs, regulates oligodendrocyte process extension (Stariha et al, 1997) and can affect microtubule dynamics (Gotoh et al, 1991). Although these results show that oligodendrocytes are sensitive to Sema3A, other signals might also be mediated by Ulip/CRMPs (Wang and Strittmatter, 1997).…”

Multiplexed RNA trafficking in oligodendrocytes and neurons

“…RNA granules contain both plus end (conventional kinesin) and minus end (cytoplasmic dynein) motors and exhibit bi-directional transport in processes and dendrites. In oligodendrocyte processes microtubules are oriented predominantly plus end out which means that anterograde granule transport requires kinesin activity while retrograde transport requires dynein activity [16]. This was demonstrated by microinjecting function-blocking antibodies to different motor proteins into oligodendrocytes [17].…”

Process Outgrowth of Oligodendrocytes Is Promoted by Interaction of Fyn Kinase with the Cytoskeletal Protein Tau

“…In the Taiep mutant rat, the polarized orientation of microtubules (Lunn et al, 1997) is abnormal, and Tau protein accumulates in the cell body and processes of oligodendrocytes, resulting in an intracellular accumulation of myelin proteins, hypomyelination, and progressive demyelination (Song et al, 2001a,b). This study highlights the interplay of Tau and microtubules and the importance of microtubules in the transport of vesicles containing myelin components to the forming sheath.…”