Expression of FGF Receptors 1, 2, 3 in the Embryonic and Postnatal Mouse Brain Compared with <i>Pdgfrα, Olig2</i> and <i>Plp/dm20:</i> Implications for Oligodendrocyte Development

Abstract

Fibroblast growth factors (FGF) receptors FgfR1, FgfR2 and FgfR3 are differentially regulated during oligodendrocyte (OL) maturation in vitro: FgfR3 is expressed by OL progenitors whereas FgfR2 is expressed by differentiated OLs[Mol Cell Neurosci 1996;7:263–275], and we have recently shown that FgfR3 is required for the timely differentiation of OLs in vivo [J Neurosci 2003;23:883–894].Here we have used in situhybridization to investigate the expression patterns of FgfR1–3 and compare them to the putative OL progenitor markers Olig2, Pdgfrαand Plp/dm20 as a function of development in vivo, in particular at sites of OL specification, migration or differentiation in the mouse forebrain and cerebellum. We show that at early stages FgfR1–3 expression overlaps with that of Olig2 in the embryonic ventricular zone of the lateral and medial ganglionic eminences. Further, a scattered population of cells expressing FgfR3 (but not FgfR1 or FgfR2) in the ventral telencephalon appear to arise from the ventricular zone, and at later stages are found more dorsally in the cortex, in an overall pattern similar to Olig2 and/or Pdgfrα. Postnatal expression of FgfR2 increases with age, more prominently in specific regions, including the cortical and cerebellar white matter and optic nerve. Thus, the differential expression pattern of FgfR2 and FgfR3 observed in vivo suggests that their expression is developmentally regulated in a manner consistent with the pattern of their expression in culture. These data provide further insights into role of FgfRs in OL development, and they emphasize that these receptors are positioned both spatially and temporally to impact OL generation in vivo.

Distinct Fibroblast Growth Factor (FGF)/FGF Receptor Signaling Pairs Initiate Diverse Cellular Responses in the Oligodendrocyte Lineage

“…Because extension of cellular processes is essential for the myelination of axons by OLs, FGF-9/FGFR2 signaling may have relevance for myelination in vivo. Consistent with this, FGF-9 and FGFR2 are expressed in the white matter, including the active phase of myelination (Tagashira et al, 1995;Miyake et al, 1996;Nakamura et al, 1999;Bansal et al, 2003b). It is interesting to note that, although FGF-2 induces process elongation, it also downregulates the synthesis of myelin proteins, accompanied by loss of membranes.…”

BMP signaling through BMPRIA in astrocytes is essential for proper cerebral angiogenesis and formation of the blood–brain-barrier

“…2A). Olig1 is expressed in neural progenitors especially in the ventricular zone of medial and lateral ganglionic eminences at E12.5 (Bansal et al, 2003). On the other hand, Emx1 is expressed in the progenitors of excitatory neurons in ventricular zone.…”

Olig Transcription Factors Are Expressed in Oligodendrocyte and Neuronal Cells in Human Fetal CNS

“…Digoxigenin was used to label RNA probes for Olig1 and Olig2 that were cloned on the basis of the GenBank published sequences AP000109 and Q13516, respectively (Lu et al, 2001). Protocol for the in situ hybridization was similar to the one published previously (Bansal et al, 2003). Sections were kept overnight at 65°C in hybridization solution containing 50% formamide, 4ϫ SSC, and 1% SDS.…”