FGF-2 Deficiency Does Not Influence FGF Ligand and Receptor Expression during Development of the Nigrostriatal System

Abstract

Secreted proteins of the fibroblast growth factor (FGF) family play important roles during development of various organ systems. A detailed knowledge of their temporal and spatial expression profiles, especially of closely related FGF family members, are essential to further identification of specific functions in distinct tissues. In the central nervous system dopaminergic neurons of the substantia nigra and their axonal projections into the striatum progressively degenerate in Parkinson's disease. In contrast, FGF-2 deficient mice display increased numbers of dopaminergic neurons. In this study, we determined the expression profiles of all 22 FGF-ligands and 10 FGF-receptor isoforms, in order to clarify, if FGF-2 deficiency leads to compensatory up-regulation of other FGFs in the nigrostriatal system. Three tissues, ventral mesencephalon (VM), striatum (STR) and as reference tissue spinal cord (SC) of wild-type and FGF-2 deficient mice at four developmental stages E14.5, P0, P28, and adult were comparatively analyzed by quantitative RT-PCR. As no differences between the genotypes were observed, a compensatory up-regulation can be excluded. Moreover, this analysis revealed that the majority of FGF-ligands (18/22) and FGF-receptors (9/10) are expressed during normal development of the nigrostriatal system and identified dynamic changes for some family members. By comparing relative expression level changes to SC reference tissue, general alterations in all 3 tissues, such as increased expression of FGF-1, -2, -22, FgfR-2c, -3c and decreased expression of FGF-13 during postnatal development were identified. Further, specific changes affecting only one tissue, such as increased FGF-16 (STR) or decreased FGF-17 (VM) expression, or two tissues, such as decreased expression of FGF-8 (VM, STR) and FGF-15 (SC, VM) were found. Moreover, 3 developmentally down-regulated FGFs (FGF-8b, FGF-15, FGF-17a) were functionally characterized by plasmid-based over-expression in dissociated E11.5 VM cell cultures, however, such a continuous exposure had no influence on the yield of dopaminergic neurons in vitro.

Fibroblast Growth Factor Receptor Signaling in Oligodendrocytes Regulates Myelin Sheath Thickness

“…Thus, Fgfr1/Fgfr2-mediated regulation of myelin growth can be genetically uncoupled as a late aspect of oligodendrocyte differentiation, coinciding with a late temporal upregulation of FGFs and FGF-receptors in the postnatal CNS. An approximately fifteen-fold increase in the levels of FGF1 and a 2–4 fold increase in the levels of FGF2, FGF22 and FGF3 transcripts (Ratzka et al, 2011) and of FGF2 protein (Riva and Mocchetti, 1991) were reported in the adult spinal cord relative to their levels at birth. At the receptor level, Fgfr2 expression begins late in oligodendrocyte-lineage cells and Fgfr1 is upregulated upon oligodendrocyte terminal differentiation, concomitant with the expression of major myelin protein genes (Fortin et al, 2005).…”

“…Neurons and astrocytes produce several FGFs, prominently FGF1 and FGF2 which are expressed concomitantly with active myelination and are also identified in axons (Riva and Mocchetti, 1991; Elde et al, 1991; Matsuyama et al, 1992; Gómez-Pinilla et al, 1992; Nakamura et al, 1999; Ratzka et al, 2011; Becker-Catania et al, 2011). Oligodendrocyte-lineage cells express FGF-receptors in a developmentally regulated manner (Bansal et al, 1996; Fortin et al, 2005).…”

Cooperation of Nuclear Fibroblast Growth Factor Receptor 1 and Nurr1 Offers New Interactive Mechanism in Postmitotic Development of Mesencephalic Dopaminergic Neurons

“…Wildtype (WT, FGF-2 ϩ/ϩ ) and knockout (KO, FGF-2 Ϫ/Ϫ ) littermates were obtained by cross-breeding of heterozygous FGF-2 mice and genotyped by PCR as described previously (27). Dissected embryonic brains (E14.5) were fixed in 4% paraformaldehyde in PBS overnight at 4°C, cryoprotected overnight in 30% (w/w) sucrose, and embedded in Tissue Tec OTC compound (Sakura).…”

Nanotechnology versus stem cell engineering: in vitro comparison of neurite inductive potentials

“…19 The plasmids encoding for enhanced green fluorescent protein (EGFP, pCAGGS-EGFP-Flag) and FGF-2 18kDa (pCAGGS-FGF-2 18kDa -Flag, NCBI GenBank accession NM_019305.2, 533-994 bp) have been previously described. 20,21 The pCAGGS-GDNF-Flag plasmid was constructed by polymerase chain reaction-based cloning of the rat GDNF coding sequence (NCBI GenBank accession NM_019139.1, 50-682 bp) using primers introducing MfeI and XbaI cloning sites and removing the stop codon. The in-frame cloned C-terminal 3× Flag tag of the pCAGGS-Flag vector backbone enabled convenient detection of all three proteins (EGFPFlag, FGF-2 18kDa -Flag, GDNF-Flag) with the same antibody (anti-Flag M2, F1804 Sigma-Aldrich, Seelze, Germany).…”