High Glucose and Advanced Glycosylation Endproducts (AGE) Modulate the CD2AP Expression in Glomerular Epithelial Cells (GEpC)

Ha, Tae Sun

Abstract

BACKGROUND
Regardless of the underlying diagnosis, the proteinuric condition demonstrates ultrastructural changes in podocytes with retraction and effacement of the foot processes and componental changes in slit diaphragm. We examined the molecular basis for this alteration of the podocyte phenotype, involving quantitative and distributional changes especially on CD2AP as a candidate regulating the modulation of pathogenic changes in the barrier to protein filtration. METHODS: To investigate whether high glucose and AGE induce podocyte cytoskeletal changes, we cultured rat GEpC under normal (5 mM) or high glucose (HG, 30 mM) and AGE- or BSA-added conditions and examined the distribution of CD2AP by confocal microscope and measured the change of CD2AP expression by Western blotting and RT-PCR. RESULTS: We found that CD2AP moved from peripheral to inner cytoplasm in the HG condition by confocal microscopy. In Western blotting, administration of high glucose or AGE decreased the CD2AP productions by 36.9% (p<0.05) and 16.0% (p< 0.05), respectively. Furthermore, both high glucose and AGE decreased the amount of CD2AP more significantly by 64.6% compared to those of control (p<0.01). Such changes was not seen in osmotic control. In RT-PCR, administration of high glucose, AGE or both high glucose and AGE decreased the expression of CD2AP mRNA by 44.9%, 27.9%, and 29.3% (p<0.05), respectively, compared to that of control. CONCLUSION: We could find that HG induce the inward translocation of CD2AP molecule and HG and AGE suppress the production of CD2AP at transcriptional and partly translational level. We suggest that these changes may explain the structural and functional changes of podocytes in diabetic conditions.