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Localization of PDGF alpha-receptor in the developing and mature human kidney
J Floege1, K L Hudkins, R A Seifert
1Division of Nephrology, Medical School, Hannover, Germany.
Abstract:
Using in situ hybridization and immunocytochemistry we describe the renal localization of the PDGF alpha-receptor. PDGF alpha-receptor mRNA was uniformly present in human metanephric kidney in interstitial cells and vascular arcades that course through the blastema. PDGF alpha-receptor mRNA was present in some mesangial structures in early glomeruli, but was largely lost as glomeruli matured. It was present in adventitial fibroblasts, but usually not in vascular smooth muscle cells or endothelial cells of the fetal vasculature. This pattern persisted in adult kidneys, with extensive expression of mRNA by interstitial cells and only occasional expression by mesangial cells. All in situ hybridization findings were corroborated by immunocytochemistry. Double immunolabeling confirmed the rare expression of the PDGF alpha-receptor protein by vascular smooth muscle cells and the absence of its expression by endothelial cells. Given that both PDGF A- and B-chain can promote smooth muscle cell and fibroblast migration and proliferation and that both signal through the PDGF alpha-receptor, these data suggest that PDGF alpha-receptor may play important roles in the early vasculogenesis of the fetal kidney as well as in the pathogenesis of renal interstitial fibrosis.
Insights
The PDGF alpha-receptor is found in developing human kidney cells, particularly interstitial cells and early blood vessels. Its presence suggests roles in kidney development and fibrosis.
Area of Science:
- Nephrology
- Developmental Biology
- Molecular Biology
Background:
- The platelet-derived growth factor (PDGF) alpha-receptor is crucial for cell signaling.
- Understanding its localization in the kidney is key to understanding kidney development and disease.
Purpose of the Study:
- To determine the precise renal localization of the PDGF alpha-receptor in human fetal and adult kidneys.
- To elucidate the potential roles of PDGF alpha-receptor in kidney development and interstitial fibrosis.
Main Methods:
- In situ hybridization was used to detect PDGF alpha-receptor mRNA.
- Immunocytochemistry and double immunolabeling were employed to visualize the protein expression.
- Human metanephric kidneys (fetal and adult) were analyzed.
Main Results:
- PDGF alpha-receptor mRNA was abundant in interstitial cells and vascular arcades of fetal kidneys.
- Expression decreased in mature glomeruli but persisted in adult interstitial cells.
- Protein expression was confirmed in interstitial cells and fibroblasts, with rare detection in vascular smooth muscle cells and absence in endothelial cells.
Conclusions:
- PDGF alpha-receptor is widely expressed in developing and adult kidney interstitial cells and vasculature.
- Its localization suggests a role in fetal kidney vasculogenesis.
- The receptor may also be implicated in the pathogenesis of renal interstitial fibrosis.