In the present study, two series of experiments were done with PAN nephropathy rats given fibroblast growth factor 2 (FGF2) or FGF2 neutralizing antibodies. In the first series of experiments, a dose of 10 micrograms of FGF2 (FGF2 group), 40 micrograms of an FGF2 neutralizing antibody (Anti-FGF2 group) or an equal volume of physiological saline (Control group) was administered for four days after PAN injection. Urinary protein increased more in the FGF2 group than in the other two groups. PCNA (+) glomerular cells were found in decreasing order in groups FGF2, Control and Anti-FGF2. Most of the PCNA (+) cells were podocytes and epithelial cells of Bowman's capsule. Staining for desmin, a marker of podocyte injury, was significantly reduced in the Anti-FGF2 group. Glomerular adhesive lesions were found in decreasing order in groups FGF2, Control and Anti-FGF2. The second series of experiments was designed to study the effects of FGF2 neutralizing antibody (40 micrograms for 5 days after PAN injection, in MoAb group) on severely damaged podocytes caused by repeated (two courses) injections in the PAN nephropathy rats. The results were the same as those in series 1. An increase in urinary protein excretion was observed in both groups, but on the 40th day, the level of proteinuria in the MoAb group decreased abruptly. It was observed that the MoAb group had few adhesive glomeruli compared to the IgG group (administration of mouse IgG) and the PCNA (+) epithelial cells of Bowman's capsule were also few. It was supposed that FGF2 would promote the formation of adhesive lesions by stimulating the proliferation of podocytes and epithelial cells of Bowman's capsule. Additionally, FGF2 itself was thought to impair podocytes because of the increasing desmin score and proteinuria.
It has been shown that mirrorimage duplications of the zeugopodia and digits are formed when MRC-5 fibroblasts producing hepatocyte growth factor (HGF) are applied to the anterior region of the chick limb bud (Yonei et al.[1993] Dev. Biol. 16024C253). To evaluate the role of HGF in limb development, we observed the expression pattern of the HGF gene using in situ hybridization. The HGF gene was expressed in the mesoderm of the limb bud and in the central core region of mandibular arch and maxillary processes at stages 17 to 24. When both wing and leg buds begin to extend distally, the HGF gene is expressed in the mesenchymal cells, but not in the ectodermal cells and somites. Concomitant with establishment of the apical ectodermal ridge, distal mesenchymal cells of the limb bud express the HGF gene intensely with a gradient higher in the distal region. The HGF expression is later confined to the ventral and subapical mesenchyme of the limb bud, although no signal is detectable in the apical and non-ridge ectoderm. However, signal for the c-met proto-oncogene encoding the HGF receptor is not detectable in the limb bud at stages 17 to 24. These results suggest that HGF produced in the limb mesoderm may be involved in initial induction and maintenance of the apical ectoderm during limb development.
We have isolated two members of the Wnt gene family, Wnt-4 and Wnt-11, from chick embryo cDNA library, and determined the entire coding sequences. The Wnt-4 and Wnt-11 genes encode secretory proteins composed of 351 and 354 amino acids, respectively, both having 24 Cys residues conserved among other Wnt family members. Alignment of the deduced amino acid sequences reveals that chicken Wnt-4 and Wnt-11 are most similar to Xenopus Wnt-4 and mouse Wnt-11; respectively. Northern blot analysis indicates the Wnt-4 expression at 1.5 kilobase and the Wnt-11 expression at 2.0 kilobase in the chick embryo.
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