J Korean Soc Pediatr Nephrol.  2004 Oct;8(2):138-148.

Effects of High Glucose and Advanced Glycosylation Endproducts (AGE) on ZO-1 Expression in cultured Glomerular Epithelial Cells (GEpC)

• Ha TS
• Lee JS
• Lee HS
• Yoon OJ

Abstract

PURPOSE: Regardless of the underlying diseases, the proteinuric condition demonstrates ultrastructural changes in podocytes with retraction and effacement of the highly specialized interdigitating foot processes. We examined the molecular basis for this alteration of the podocyte phenotypes, including quantitative and distributional changes of ZO-1 protein as a candidate contributing to the pathogenic changes in the barrier to protein filtration.
METHODS
To investigate whether high glucose and advanced glycosylation endproduct(AGE) induce podocyte cytoskeletal changes, we cultured rat GEpC under 1) normal glucose(5 mM, =control) or 2) high glucose(30 mM) or 3) AGE-added or 4) high glucose plus AGE-added conditions. The distribution of ZO-1 was observed by confocal microscope and the change of ZO-1 expression was measured by Western blotting and RT-PCR.
RESULTS
By confocal microscopy, we observed that ZO-1 moves from peripheral cytoplasm to inner actin filaments complexes in both AGE-added and high glucose condition. In Western blotting, high glucose or AGE-added condition decreased the ZO-1 protein expression by 11.1%(P>0.05) and 2.3%(P>0.05), respectively compared to the normal glucose condition. High glucose plus AGE-added condition further decreased ZO-1 protein expression to statistically significant level(12%, P<0.05). No significant change was seen in the osmotic control. In RT-PCR, high glucose plus AGE-added condition significantly decreased the expression of ZO-1 mRNA by 12% compared to normal glucose condition.
CONCLUSION
We suggest that both high glucose and AGE-added condition induce the cytoplasmic translocation and suppresses the production of ZO-1 at transcriptional level and these changes may explain the functional changes of podocytes in diabetic conditions.

Keyword

Diabetic nephropathy; Advanced glycosylation endproducts; ZO-1; Glomerular epithelial cells; Podocyte

MeSH Terms

Actin Cytoskeleton
Animals
Blotting, Western
Cytoplasm
Diabetic Nephropathies
Epithelial Cells*
Filtration
Foot
Glucose*
Glycosylation*
Microscopy, Confocal
Phenotype
Podocytes
Rats
RNA, Messenger
Staphylococcal Protein A
Glucose
RNA, Messenger
Staphylococcal Protein A