Light-microscopic immunolocalization of fibroblast growth factor-1 and -2 in adult rat kidney

Abstract

The fibroblast growth factors (FGFs) are a family of conserved polypeptides known to regulate cell differentiation and proliferation. We have used avidin-biotin-enhanced indirect immunohistochemistry to localize FGF-1 and FGF-2 in the rat kidney. The most consistent specific immunostaining pattern is found in paraffin sections from kidneys perfusion-fixed with 4% paraformaldehyde in 0.1 M phosphate buffer. Intracellular immunoreactivity for FGF-1 and FGF-2 is co-localized in visceral (podocytes) and parietal (Bowman's capsule) glomerular epithelial cells, S3 segments of proximal tubules, distal tubules and collecting ducts in the cortex, and thick ascending limbs and collecting ducts in the medulla. Immunoreactivity is also observed within urothelium and the tunica adventitia of large blood vessels. No immunostaining is found in cortical S1 or S2 segments of proximal tubules, in frozen sections prepared from unfixed or 4% paraformaldehyde perfusion-fixed kidneys, or in paraffin sections from Bouin-fixed kidneys. Immersion fixation with 4% paraformaldehyde gives a similar staining pattern in paraffin sections to that achieved with perfusion fixation. However, in paraffin sections fixed with methyl Carnoy's fixative, immunoreactivity is primarily localized to the tunica media of blood vessels, with little tubular or glomerular immunostaining. Thus, variation in immunolocalization patterns for FGFs can be partially attributed to differences in fixative, preparative technique and antibody specificity.

Role of basic fibroblast growth factor (FGF-2) in diabetic nephropathy and mechanisms of its induction by hyperglycemia in human renal fibroblasts

“…In adult human kidney, FGF-2 expression has been described in glomerular endothelial, parietal, and visceral cells, tubular epithelial cells, and interstitial fibroblasts (5,11,37). Our data demonstrated an upregulated expression of FGF-2 in DN in vivo.…”

Glypican-5 Increases Susceptibility to Nephrotic Damage in Diabetic Kidney

“…27,30 Therefore, we sought to detect intraglomerular gene expression of FGF2. However, our glomerular analysis using in situ hybridization of FGF2 and immortalized cell lines showed virtually undetectable increased expression in the diabetic kidney.…”

Immunohistochemical Study Of Nestin and Fibroblast Growth Factor 9 (FGF9) in Rabbit Kidney During Postnatal Development

“…the complete loss of Fgf9 function during kidney development results in a failure of nephron formation prior to the S-shaped body stage. Cauchi et al (1996) reported that FGF-1 and FGF-9 proteins are localized in glomeruli, proximal tubules, distal tubules, and collecting ducts of adult rat kidneys. In adult rat kidneys, FGF9 has been localized in medullary interstitial cells (Ichimura et al, 1996).…”