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Localization of fibroblast growth factor-2 (basic FGF) and FGF receptor-1 in adult human kidney
J Floege1, K L Hudkins, F Eitner
1Division of Nephrology, Medical School, Hannover, Germany.
Background:
The expression pattern of fibroblast growth factor-2 (FGF-2; basic FGF), a pleiotrophic growth factor, as well as one of its receptors (FGFR1), in the kidney is highly controversial.
Methods:
Using an approach that combines multiple antibodies for immunohistochemistry and correlative in situ hybridization, we assessed the intrarenal expression of both FGF-2 and FGFR1 in 13 specimens of adult kidney removed during tumor nephrectomy.
Results:
The FGF-2 expression pattern in the kidneys as detected by immunohistochemistry was variable and depended on the antibody used. The most consistent expression of FGF-2 protein was demonstrated in glomerular parietal epithelial cells, tubular cells (mainly of the distal nephron), as well as arterial endothelial cells. These locations also corresponded to areas of FGF-2 mRNA expression. Additionally, by immunohistochemistry, FGF-2 protein was detected in arterial smooth muscle cells and occasional podocytes. The expression of FGFR1 protein and mRNA was most consistently present in tubular cells of the distal nephron and in vascular smooth muscle cells. In situ hybridization, but not immunohistochemistry, also suggested FGFR1 expression in cells that could not be precisely identified within the glomerular tuft as well as some interstitial cells.
Conclusion:
These data suggest potential autocrine and paracrine pathways within the FGF-2 system, particularly within the vascular walls and in the distal nephron, and thereby provide information for further mechanistic understanding of the role of the FGF-2 system in human renal disease.
Insights
This study clarifies the kidney expression of fibroblast growth factor-2 (FGF-2) and its receptor (FGFR1), revealing potential autocrine and paracrine signaling pathways in renal disease.
Area of Science:
- Nephrology
- Molecular Biology
- Cell Biology
Background:
- The intrarenal expression of fibroblast growth factor-2 (FGF-2) and its receptor (FGFR1) is poorly understood and debated.
- Accurate localization is crucial for understanding FGF-2's role in kidney physiology and pathology.
Purpose of the Study:
- To precisely map the expression patterns of FGF-2 and FGFR1 within the adult human kidney.
- To investigate potential autocrine and paracrine signaling mechanisms involving FGF-2 in the kidney.
Main Methods:
- Utilized immunohistochemistry with multiple antibodies and in situ hybridization.
- Analyzed 13 adult human kidney specimens obtained during tumor nephrectomy.
Main Results:
- FGF-2 protein and mRNA were consistently detected in glomerular parietal epithelial cells, distal nephron tubular cells, and arterial endothelial cells.
- FGFR1 protein and mRNA were primarily found in distal nephron tubular cells and vascular smooth muscle cells.
- Immunohistochemistry and in situ hybridization revealed FGF-2 in arterial smooth muscle cells and podocytes, and FGFR1 in interstitial cells.
Conclusions:
- The findings suggest the presence of FGF-2 autocrine and paracrine signaling pathways within the kidney, particularly in vascular walls and the distal nephron.
- This provides a foundation for understanding the FGF-2 system's role in human renal diseases.