The Early Steps of Oligodendrogenesis: Insights from the Study of the plp Lineage in the Brain of Chicks and Rodents

Abstract

Oligodendrocytes are the myelin-forming cells of the central nervous system. Over the last decade, their development in the embryonic brain and spinal cord has been documented following the discovery of early oligodendroglial markers. These early expressed oligodendroglial genes nevertheless show differences in their spatiotemporal pattern of expression and it is not yet clear if their expression is linked in a linear way. This review highlights the common themes underlying the spatiotemporal aspects of oligodendrogenesis in chick and rodent brain and discusses some recent advances in the knowledge of the cell lineage expressing plp, one of the early oligodendroglial genes. We suggest a model of oligodendroglial commitment whereby definitive oligodendroglial progenitor formation is preceded by a primitive neuroglial progenitor stage and whereby different oligodendrocyte lineages might segregate from either plp-positive or plp-negative primitive progenitor cells.

Spatiotemporal gradient of oligodendrocyte differentiation in chick optic tectum requires brain integrity and cell‐cell interactions

“…MAG expression most likely occurs after migration of progenitors because MAG ϩ cells are found predominantly in the axonal layers that they myelinate. This makes MAG a later marker for oligodendrocytes than some other markers that are expressed before and during migration, such as O4, O1, PDGFR␣, or plp (PerezVillegas et al, 1999;Thomas et al, 2000;Davies and Miller, 2001;Olivier et al, 2001;Ono et al, 2001;Spassky et al, 2001). Consequently, MAG can be considered a more definitive marker for oligodendrocytes in chick brain than earlier markers that identify progenitors.…”

Efficient Isolation and Gene Expression Profiling of Small Numbers of Neural Crest Stem Cells and Developing Schwann Cells

“…Plp-GFP transgenic animals (line 42) (Spassky et al, 2001) were provided by B. Zalc (Institut National de la Santé et de la Recherche Médicale U-495, Hôpital de la Salpêtrière, Paris). Heterozygous embryos or pups were obtained by mating homozygous transgenic males with C57BL/6 females, taking the date of the vaginal plug as E0.…”

“…We tested a transgenic mouse line in which Plp promoter elements drive expression of GFP (Spassky et al, 2001). Green fluorescence was apparent in the region of the somites in whole embryos at E9.5 (Fig.…”

“…Recently, animals expressing fluorescent proteins under the control of various tissue-specific promoters have been used to retrieve specific cell types from a complex mixture of cells by fluorescence-activated cell sorting (FACS). In particular, developing and mature oligodendrocytes have been isolated from brains and spinal cords of mice expressing green fluorescent protein (GFP) under the control of the proteolipid protein (Plp) promoter (Fuss et al, 2000;Spassky et al, 2001). Because the Plp promoter is also active in Schwann cell (SC) precursor cells of the peripheral nervous system (PNS) (Griffiths et al, 1998), mice expressing GFP under its control appeared promising for exploring gene expression in early development of the PNS.…”

Oligodendrocyte development in the embryonic brain: the contribution of the plp lineage

“…Their specification and migration have been analyzed both in chick and mouse species and we have searched for molecules guiding plp + OPC migration from the ventricular foci towards the future white matter tracts. The resulting findings were: i) a spatio-temporal description of oligodendrogenesis and OPC migratory pathways in the mouse and chick embryonic brain (Spassky et al, 1998(Spassky et al, , 2001bPerez-Villegas et al, 1999;Olivier et al, 2001); ii) the characterization of plp + OPCs as PDGF-A independent precursors, thus distinct from PDGFRα expressing OPCs (Spassky et al, 2001a); iii) the identification of molecules controling OPC migration, some of which act from a distance, like the axonal guidance molecules class 3 semaphorins and netrin-1 (Spassky et al, 2002), while others mediate their effect by a direct cell to cell contact, like the ephrinB2 ligand (Prestoz et al, 2004).…”