J Korean Med Sci.  2011 Oct;26(10):1316-1321. 10.3346/jkms.2011.26.10.1316.

Ginseng Total Saponin Improves Podocyte Hyperpermeability Induced by High Glucose and Advanced Glycosylation Endproducts

• Ha TS
• Choi JY
• Park HY
• Lee JS

• KMID: 1785989
• DOI: http://doi.org/10.3346/jkms.2011.26.10.1316

Abstract

Early diabetic nephropathy is characterized by glomerular hyperpermeability as a result of impaired glomerular filtration structure caused by hyperglycemia, glycated proteins or irreversible advanced glycosylation endproducts (AGE). To investigate the effect of ginseng total saponin (GTS) on the pathologic changes of podocyte ZO (zonula occludens)-1 protein and podocyte permeability induced by diabetic conditions, we cultured mouse podocytes under: 1) normal glucose (5 mM, = control); 2) high glucose (HG, 30 mM); 3) AGE-added; or 4) HG plus AGE-added conditions and treated with GTS. HG and AGE increased the dextran filtration of monolayered podocytes at early stage (2-8 hr) in permeability assay. In confocal imaging, ZO-1 colocalized with actin filaments and beta-catenin at cell contact areas, forming intercellular filtration gaps. However, these diabetic conditions suppressed ZO-1 immunostainings and disrupted the linearity of ZO-1. In Western blotting, diabetic conditions also decreased cellular ZO-1 protein levels at 6 hr and 24 hr. GTS improved such quantitative and qualitative changes. These findings imply that HG and AGE have an influence on the redistribution and amount of ZO-1 protein of podocytes thereby causing hyperpermeability at early stage, which can be reversed by GTS.

Keyword

Ginseng Total Saponin; Podocytes; ZO-1; Advanced Glycosylation Endproducts; Diabetic nephropathies

MeSH Terms

Actin Cytoskeleton/metabolism
Animals
Cell Line
Diabetic Nephropathies/physiopathology
Glomerular Filtration Rate
Glucose/*pharmacology
Glycosylation End Products, Advanced/*pharmacology
Hyperglycemia/physiopathology
Membrane Proteins/*metabolism
Mice
*Panax
Permeability/drug effects
Phosphoproteins/*metabolism
Plant Preparations/*pharmacology
Podocytes/drug effects/pathology/physiology
Saponins/*pharmacology
beta Catenin/metabolism

Figure

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  Fig. 1 Effects of ginseng total saponin (GTS) on the increased monolayered podocyte permeability by diabetic conditions. High glucose (B30) increases permeability at early stage (A) and AGE and high glucose (A30) also increases permeability at mid stage (B).

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  Fig. 2 Distributional changes of ZO-1 by diabetic conditions and ginseng total saponin (GTS). ZO-1 colocalizes with actin filaments (A) and β-catenin (B) at cell contact areas. Diabetic conditions including B30, A5, and A30 suppresses and disrupts the immunostainings and linearity of ZO-1 protein (arrows, B and C), which improved by GTS (1 µg/mL) (C). Magnification, × 1,000; Scale bar = 20 µm.

• 

  Fig. 3 Effects of diabetic conditions and ginseng total saponin (GTS) on the ZO-1 protein assayed by Western blotting. The major band for ZO-1 protein at 205 kDa decreased in B30 and A30 conditions at 6 and 24 hr incubations, which improved by GTS (1 µg/mL) (A, B). Data on the densitometric analysis of ZO-1/β-tubulin (not shown) ratio are expressed as mean ± SD (n = 4). Control (100%); the value of B5. *P < 0.01 versus control.

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