Cytoplasmic Localization of WT1 and Decrease of miRNA-16-1 in Nephrotic Syndrome.

Pablo Zapata-Benavides,Esperanza Avalos-Díaz,Rafael Herrera-Esparza,Mariela Arellano-Rodríguez,Moisés Armides Franco-Molina,Gloria Azucena Rangel-Ochoa,Juan José Bollain-Y-Goytia,Cristina Rodríguez-Padilla

doi:10.1155/2017/9531074

Pablo Zapata-Benavides, Esperanza Avalos-Díaz + Show 6 more

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https://doi.org/10.1155/2017/9531074

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Abstract

Nephrotic syndrome (NS) is a glomerular disease that is defined by the leakage of protein into the urine and is associated with hypoalbuminemia, hyperlipidemia, and edema. Steroid-resistant NS (SRNS) patients do not respond to treatment with corticosteroids and show decreased Wilms tumor 1 (WT1) expression in podocytes. Downregulation of WT1 has been shown to be affected by certain microRNAs (miRNAs). Twenty-one patients with idiopathic NS (68.75% were SSNS and 31.25% SRNS) and 10 healthy controls were enrolled in the study. Podocyte number and WT1 location were determined by immunofluorescence, and the serum levels of miR-15a, miR-16-1, and miR-193a were quantified by RT-qPCR. Low expression and delocalization of WT1 protein from the nucleus to the cytoplasm were found in kidney biopsies of patients with SRNS and both nuclear and cytoplasmic localization were found in steroid-sensitive NS (SSNS) patients. In sera from NS patients, low expression levels of miR-15a and miR-16-1 were found compared with healthy controls, but only the miR-16-1 expression levels showed statistically significant decrease (p = 0.019). The miR-193a expression levels only slightly increased in NS patients. We concluded that low expression and delocalization from the WT1 protein in NS patients contribute to loss of podocytes while modulation from WT1 protein is not associated with the miRNAs analyzed in sera from the patients.

Highlights

Nephrotic syndrome (NS) is one of the most common diseases in children and is characterized by the leakage of large amounts of protein into the urine, lipidemia, hypoalbuminemia, and dysfunction of the glomerular filtration barrier [1]; NS is a major cause of podocyte injury [2]
Twenty-one biopsies, serum and urine samples from 11 males and 10 females, from patients diagnosed with NS who met the criteria of International Study of Kidney Disease in Children with proteinuria levels greater than 3.5 g/24 h were included, in the control group serum and urine samples were obtained from 10 subjects without kidney disease, renal biopsies were obtained of autopsy subjects without renal disease who died in accidents as a result of a head injury
The localization assay was performed by the colocalization of DAPI and Texas Red (WT1), showing a statistically significant difference between sensitive NS (SSNS) (PPC = 0.51 ± 0.03) and Steroid-resistant NS (SRNS) (PPC = 0.29 ± 0.01) patients compared with healthy subjects (PPC = 0.73 ± 0.02) (p = 0.00001) (Figure 1(c))

Summary

Introduction

Nephrotic syndrome (NS) is one of the most common diseases in children and is characterized by the leakage of large amounts of protein into the urine, lipidemia, hypoalbuminemia, and dysfunction of the glomerular filtration barrier [1]; NS is a major cause of podocyte injury [2]. The reduction of glomerular podocytes in lupus nephritis (LN) patients is correlated with the cumulative loss of urinary podocytes and proteinuria during the progression of kidney disease [2, 4]. Some urinary biomarkers have been found to be associated with injured podocytes in urine sediment, such as podocalyxin (PODXL), nephrin (NPHS1), podocin, and Wilms tumor protein (WT1) [5]. The WT1 gene encodes for a transcription factor that is critical for the development of podocytes and viability; the regulation of podocyte homeostasis occurs via PODXL and NPHS1 [7]

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