Elevated glucose represses lysosomal and mTOR-related genes in renal epithelial cells composed of progenitor CD133+ cells.

Swojani Shrestha,Bethany A Davis,Matthew Kalonick,Sandeep Singhal,Donald A Sens,Rachel Guyer,Spencer Breen,Seema Somji,Scott H Garrett,Benedetta Bussolati

doi:10.1371/journal.pone.0248241

Swojani Shrestha, Bethany A Davis + Show 8 more

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https://doi.org/10.1371/journal.pone.0248241

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Abstract

Hyperglycemia is one of the major health concern in many parts of the world. One of the serious complications of high glucose levels is diabetic nephropathy. The preliminary microarray study performed on primary human renal tubular epithelial (hRTE) cells exposed to high glucose levels showed a significant downregulation of mTOR as well as its associated genes as well as lysosomal genes. Based on this preliminary data, the expression of various lysosomal genes as well as mTOR and its associated genes were analyzed in hRTE cells exposed to 5.5, 7.5, 11 and 16 mM glucose. The results validated the microarray analysis, which showed a significant decrease in the mRNA as well as protein expression of the selected genes as the concentration of glucose increased. Co-localization of lysosomal marker, LAMP1 with mTOR showed lower expression of mTOR as the glucose concentration increased, suggesting decrease in mTOR activity. Although the mechanism by which glucose affects the regulation of lysosomal genes is not well known, our results suggest that high levels of glucose may lead to decrease in mTOR expression causing the cells to enter an anabolic state with subsequent downregulation of lysosomal genes.

Highlights

There is strong evidence that the renal proximal tubule is involved in the early stages, and subsequent progression, of diabetic kidney disease (DKD) [1,2,3,4,5]
The human renal tubular epithelial (hRTE) cell culture model was chosen for the present studies since they have recently been shown to be composed of approximately 60–70% of cells that possess both CD133 and CD24, with the remaining cells expressing CD24 and no CD133 [6, 7]
Our study demonstrated that the expression of SLC5A2 in the human kidney cortex is much higher than the expression in cultured hRTE cells

Summary

Introduction

There is strong evidence that the renal proximal tubule is involved in the early stages, and subsequent progression, of diabetic kidney disease (DKD) [1,2,3,4,5]. These human studies, as well as studies utilizing animal models, have been complimented by the employment of in vitro cell culture models of putative proximal tubular cells to study a large range of factors associated with DKD. Elevated glucose represses lysosomal and mTOR genes in renal epithelial cells composed of progenitor cells program P20 GM103442 from the National Institute of General Medical Sciences, NIH.

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