Expression of Wilms’ Tumor 1 Antigen, Vimentin, and Corticotropin-Releasing Factor in the Human Kidney with Focal Segmental Glomerulosclerosis and Effect of Oxidative Stress on These Markers in HEK 293 Cells

Abstract

Introduction: Wilms-tumor 1 antigen (WT1) expression in podocytes has the important role of maintaining their integrity and glomerular function. Vimentin also plays a role in preserving podocyte function and in morphologic changes observed after injury. Corticotropin releasing factor (CRF) is important in stress and in maintaining homeostasis. According to our previous studies, tyrosine (Tyr) isoforms (meta- and ortho-Tyr) may play a role in the development of many diseases. Introduction: Wilms-tumor 1 antigen (WT1) expression in podocytes has the important role of maintaining their integrity and glomerular function. Vimentin also plays a role in preserving podocyte function and in morphologic changes observed after injury. Corticotropin releasing factor (CRF) is important in stress and in maintaining homeostasis. According to our previous studies, tyrosine (Tyr) isoforms (meta- and ortho-Tyr) may play a role in the development of many diseases. Methods: Our aim was to investigate the expression of WT1, vimentin and CRF in human kidney and in HEK 293 cell cultures. Histological and clinical feature of 42 FSGS patients were evaluated and compared to patients with thin-basement membrane as a control group. Cells were cultured in medium containing para-, meta-, and ortho-tyrosine, and their expression of WT1, vimentin, and CRF were determined by immunocytochemistry. Podocyte foot process effacement was investigated by electron microscope (EM). Results: The intensity of WT1 staining in glomeruli was the same in focal segmental glomerulosclerosis (FSGS) and control groups, but it was lower in the tubulointerstitium of FSGS patients. Vimentin was lower in glomeruli of FSGS patients (p=0.009), and it was higher in the tubulointerstitium compared to the control group (p=0.003). CRF intensity was lower in the glomeruli (p=0.002). Podocyte foot process effacement determined by electron microscope (EM) showed correlation with vimentin and CRF in glomeruli. WT1 staining intensity was lower in meta- and ortho-Tyr group (p=0.001; p=0.009). Vimentin was lower in the meta-Tyr group (p=0.001). Discussion: Our observations on kidney biopsy samples support that the reduction of WT1 and vimentin could be characteristic for FSGS. Our results on HEK cells suggest that meta- and ortho-tyrosine may play a role in the development of FSGS.

Chronic Insulin Resistance and Changes of M1/M2 Polarization in Macrophages Due to Abnormal Tyrosines

“…Hyperglycaemia also has an oxidative stress-inducing effect, which may play a role in the development of insulin resistance in diabetes and its complications [10,18,29]. As a result of oxidative stress, the amount of hydroxyl free radicals increases, which leads to an increase in the meta-and ortho-Tyr products in a non-enzymatic way generated from Phe [10].…”

“…At the same time, due to the antioxidant effect of resveratrol, the excretion of ortho-Tyr in the urine decreased in patients with type 2 diabetes mellitus, and a parallel decrease in insulin resistance was observed. Furthermore, in our previous studies, we concluded that non-physiological tyrosines are not only the markers of the oxidative stress, but they may also play a role in the pathogenesis of many diseases [10,11,18]. Culturing of different cell lines on meta-and ortho-Tyr led to insulin resistance in these cells, similar to growing in a high-glucose environment.…”

“…The intensity measurement was performed with a slight modification of the method described in our previous study [18]. The images of the stained cells were scanned with a Nikon Confocal Laser Scanning Microscope system (Nikon, Tokyo, Japan).…”

Research progress of natural active compounds on improving podocyte function to reduce proteinuria in diabetic kidney disease

“…The results of renal biopsy combined with functional protein studies of podocytes showed that the normal expression of Wilms-tumor 1 (WT1) and vimentin in podocytes is closely related to the structural integrity of podocytes. Together, WT1 and vimentin maintain normal glomerular function [ 18 ]. WT1 is a nuclear protein associated with podocyte filtration function, and vimentin is a backbone protein that constitutes the podocyte cytosol and primary peduncle, both of which are essential for foot process formation.…”

“…This study concludes that WT1 is a clinically available biomarker that could improve risk stratification in patients with DKD [ 23 ]. WT1 is a Wilms tumor oncogene that is specifically expressed in podocytes and plays an important role in maintaining podocyte integrity and glomerular function [ 18 ].…”