Single or multiple oligodendroglial lineages: A controversy

Spassky, Nathalie; Olivier, C.; Pérez-Villegas, Eva María; Goujet‐Zalc, C.; Martı́nez, Salvador; Thomas, Jean‐Léon; Zalc, Bernard

doi:10.1002/(sici)1098-1136(20000115)29:2<143::aid-glia7>3.0.co;2-d

Cited by 105 publications

(60 citation statements)

References 20 publications

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“…The small proportion of Olig2+/PSA-NCAM+ cells probably represents neuronal progenitors, although it is possible that a subpopulation of oligodendrocyte progenitors during very early stages of development expresses PSA-NCAM. This would be consistent with recent reports describing various oligodendrocyte progenitors subpopulations in rodents (Spassky et al, 2000;Kessaris et al, 2006, Parras et al, 2007, and possibly in humans, as we discussed previously (Jakovcevski and Zecevic, 2005b). The fact that at midgestation glia cell populations in the human brain do not express PSA-NCAM, as has been shown in rodents, might be due to either inter-species differences or difference in studied stages of development.…”

Section: Discussionsupporting

confidence: 92%

Down-regulation of the axonal polysialic acid–neural cell adhesion molecule expression coincides with the onset of myelination in the human fetal forebrain

Jakovčevski

Zečević

2007

Neuroscience

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The polysialic acid (PSA) modification of neural cell adhesion molecule, which reduces NCAMmediated cell adhesion, is involved in several developmental processes, such as cell migration, axonal growth, pathfinding, and synaptic plasticity. It has been suggested that PSA-NCAM expression may inhibit myelination. To clarify the relationship between myelination and the expression of PSA-NCAM we systematically investigated its expression in the human forebrain from embryonic stage to midgestation (19-24 gestation weeks, gw). Immunofluorescence on cryosections showed that PSA-NCAM is expressed at the earliest stage studied (5.5 gw) in the primordial plexiform layer of the telencephalon, which mainly consists of neuronal processes. At midgestation, cortical axonal tracts in the emerging white matter were PSA-NCAM+, but they were not yet myelinated, based on the lack of myelin basic protein (MBP) immunoreaction. To follow the progression of myelination we developed organotypic slice cultures that included the subventricular and intermediate zones of the fetal forebrain. In freshly prepared slices, similar to cryosections, axonal tracts were PSA-NCAM + but did not express MBP. After 5 days in culture there was a dramatic increase in MBP expression around the axons of the intermediate zone, which suggested the onset of myelination. Simultaneously with MBP up-regulation PSA-NCAM expression in axons was completely lost, as demonstrated both with immunofluorescence and Western blot analysis. These results support the idea that in the human fetal forebrain axonal PSA-NCAM expression is inversely related to primary myelination.

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Section: Discussionsupporting

confidence: 92%

Down-regulation of the axonal polysialic acid–neural cell adhesion molecule expression coincides with the onset of myelination in the human fetal forebrain

Jakovčevski

Zečević

2007

Neuroscience

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“…Together, our studies indicate a regional difference in the regulation of Olig2 expression and oligodendrocyte development by the Nkx6.1 homeodomain transcription factor. Consistent with the previous suggestions on multiple origins of OPCs in the developing hindbrain (Spassky et al, 1998;Spassky et al, 2000;Davies and Miller, 2001), Olig1 and Olig2 are expressed in multiple ventricular and subventricular zones in the rostral hindbrain (metencephalon) at E13.5 (Fig. 8A-D), and OPC cells can be produced from the neuroepithelial cells both inside and outside the Nkx6.1-expressing domain (Figs 8, 9).…”

Section: Identity Of Nkx22-expressing Cells In Embryonic Mouse Spinasupporting

confidence: 91%

Region-specific and stage-dependent regulation of Olig gene expression and oligodendrogenesis byNkx6.1homeodomain transcription factor

Liu

Cai

et al. 2003

Development

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During early neural development, the Nkx6.1 homeodomain neural progenitor gene is specifically expressed in the ventral neural tube, and its activity is required for motoneuron generation in the spinal cord. We report that Nkx6.1 also controls oligodendrocyte development in the developing spinal cord, possibly by regulating Olig gene expression in the ventral neuroepithelium. In Nkx6.1 mutant spinal cords, expression of Olig2 in the motoneuron progenitor domain is diminished, and the generation and differentiation of oligodendrocytes are significantly delayed and reduced. The regulation of Olig gene expression by Nkx6.1 is stage dependent, as ectopic expression of Nkx6.1 in embryonic chicken spinal cord results in an induction of Olig2 expression at early stages, but an inhibition at later stages. Moreover, the regulation of Olig gene expression and oligodendrogenesis by Nkx6.1 also appears to be region specific. In the hindbrain, unlike in the spinal cord, Olig1and Olig2 can be expressed both inside and outside the Nkx6.1-expressing domains and oligodendrogenesis in this region is not dependent on Nkx6.1 activity.

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“…Previous studies suggest that oligodendroglial populations initially appear in the ventral brain structures (Spassky et al, 2000;Tekki-Kessaris et al, 2001;Woodruff et al, 2001). However, the contribution of dorsal progenitors to cortical myelination remains controversial.…”

Section: Discussionmentioning

confidence: 99%

“…However, the relative contribution of dorsal and ventral progenitor cells to oligodendrocyte myelination in the cortex is highly contended in the brain development field (Spassky et al, 2000;Woodruff et al, 2001;Marshall et al, 2003;Miller, 2005). A current view suggests that the majority of cortical oligodendrocytes are initially derived from the ventral telencephalon, populating the dorsal regions by migration and proliferation .…”

Section: Introductionmentioning

confidence: 99%

A Critical Role for Dorsal Progenitors in Cortical Myelination

et al. 2006

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Much controversy regarding the anatomical sources of oligodendrocytes in the spinal cord and hindbrain has been resolved. However, the relative contribution of dorsal and ventral progenitors to myelination of the cortex is still a subject of debate. To assess the contribution of dorsal progenitors to cortical myelination, we ablated the basic helix-loop-helix transcription factor Olig2 in the developing dorsal telencephalon. In Olig2-ablated cortices, myelination is arrested at the progenitor stage. Under these conditions, ventrally derived oligodendrocytes migrate dorsally into the Olig2-ablated territory but cannot fully compensate for myelination deficits observed at postnatal stages. Thus, spatially restricted ablation of Olig2 function unmasks a contribution of dorsal progenitors to cortical myelination that is much greater than hitherto appreciated.

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Single or multiple oligodendroglial lineages: A controversy

Cited by 105 publications

References 20 publications

Down-regulation of the axonal polysialic acid–neural cell adhesion molecule expression coincides with the onset of myelination in the human fetal forebrain

Down-regulation of the axonal polysialic acid–neural cell adhesion molecule expression coincides with the onset of myelination in the human fetal forebrain

Region-specific and stage-dependent regulation of Olig gene expression and oligodendrogenesis byNkx6.1homeodomain transcription factor

A Critical Role for Dorsal Progenitors in Cortical Myelination

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